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APPLETONS' 
 AMERICAN STANDARD GEOGRAPHIES 
 
 BASED ON THE PRINCIPLES OE THE SCIENCE OF EDUCATION 
 
 PHYSICAL GEOGRAPHY 
 
 PREPJlRED on J^ new j^NE ORiaiNJLE ELA.N 
 
 JOHN D. QUACKENBOS. A.M., M. D. (Literary Editor) 
 
 Professor Emeritus of Rhetoric, Columbia College, New York • 
 Member of the N. Y. Academy of Sciences , Fellow of the' 
 N. Y. Academy of Medicine 
 
 JOHN S. NEWBERRY, M. D., LL. D. 
 
 Late Professor of Geology and Palaeontology, Columbia Col- 
 lege, AND President of the N. Y. Academy of Sciences 
 
 CHARLES H. HITCHCOCK, Ph.D. 
 
 Professor of Geology and Mineralogy, Dartmouth College 
 
 W. LE CONTE STEVENS, Ph. D. 
 
 Professor of Physics, Rensselaer Poly'technic Institute 
 
 HENRY GANNETT 
 
 Chief Geographer of the United States Geological Survey 
 
 BY 
 
 Dr. WILLIAM H. DALL 
 
 Of the United States National Museum 
 
 C. HART MERRIAM, M. D. 
 
 Ornithologist of the Department of Agriculture 
 
 NATHANIEL L. BRITTON, E. M., Ph.D. 
 Professor of Botany, Columbia College 
 
 GEORGE F. KUNZ 
 
 Member of the N. Y. Academy of Sciences; Gem Expert 
 and Mineralogist with Messrs. Tiffany & Co. 
 
 Lieutenant GEORGE M. STONEY 
 
 Naval Department, Washington 
 
 ILLUSTRATED WITH ENGRAVINGS, DIAGRAMS, AND MAPS IN COLOR — AND INCLUDING A SEPARATE CHAPTER ON 
 THE GEOLOGICAL HISTORY AND THE PHYSICAL FEATURES OF THE UNITED STATES 
 
 NEW YORK •:• CINCINNATI •:• CHICAGO 
 
 AMERICAN BOOK COMPANY 
 
PRE FACE 
 
 As Physical Geography is a singularly comprehensive science, involving 
 applications from a great variety of cognate sciences, it is presumable that no 
 one author possesses the depth or variety of knowledge essential to the prepa- 
 ration of a successful text-booli on the subject, especially in view of the im- 
 portant advances recently made in many diverse fields of inquiry through the 
 researches of specialists. In this belief, and with the desire of presenting to 
 the public a work thoroughly abreast of the times, the editor has enlisted the 
 co-operation of a number of writers, recognized as authorities in their respect- 
 ive departments of science, and to each of these he has assigned a portion of 
 the subject, governing liis selection by the special qualifications of the author. 
 The standing and reputation of the several contributors must secure for this 
 work a value and importance possessed by few other school-texts. 
 
 The section on the general structure and geological history of the earth 
 has been prepared by Dr. John S. Newberry, Professor of Geology and Palaj- 
 ontology in Columbia College ; that devoted to the geological history of the 
 North American Continent, by Professor Cliarles H. Hitchcock, of Dartmouth 
 College ; the portion relating to general physiography and the phj'sical feat- 
 ures of the United States, by Mr. Henry Gannett, Chief Geographer of the 
 United States Geological Survey ; the pages explaining terrestrial magnetism, 
 with the chapters on volcanoes and earthquakes, coral islands, the earth's 
 waters, and meteorology, by Dr. W. Le Conte Stevens, Professor of Physics 
 in the Packer Collegiate Institute. Dr. N. L. Britton, Lecturer in Botany, 
 Columbia College, furnished the chapter on plant-life ; Dr. C. Hart Merriam, 
 the Ornithologist of the Department of Agriculture, those relating to zoology 
 and the animal life of the United States ; Professor William H. Dall, of the 
 Smithsonian Institution, that on ethnology ; and Mr. George F. Kunz, gem 
 expert and mineralogist with Messrs. Tiffany & Co., of New York, that on 
 precious stones. 
 
 Many friends of the book have given it the benefit of their suggestions 
 and criticisms. Special acknowledgment is due to Professor Egleston, of 
 Columbia College, who carefully corrected the paragraphs on mineralogy ; 
 to Commodore George E. Belknap, of the United States Navy, who examined 
 the section on the ocean and its currents, besides extending many courtesies 
 of a personal character ; to Professor Cleveland Abbe, of tlie Army Signal- 
 Office, Washington, to Professors John and Joseph Le Conte, of the Univer- 
 sity of California, to Professor Loomis, of Yale College, and to Professor 
 William Ferrel, for valuable criticisms and other assistance ; to Lieutenant 
 Schwatka, who generously placed at the editor's disposal his maps and pho- 
 tographs ; and to Lieutenant Stoney, for an instructive page on his discoveries 
 in Arctic Alaska, as well as for his aid in the construction of the map of that 
 territory. 
 
 Tlie attention of educators is invited to the following noteworthy features : 
 
 The book throughout is the product of painstaiing and critical study on 
 the part of those who have had practical experience in the lecture-room. The 
 aim of the editor and his corps of authors has been, to supply the useful ele- 
 ments in an inviting and assimilable form — to popularize the study of Physi- 
 cal Geography by furnishing a complete, attractive, carefully-condensed text- 
 book, neither encumbered with wearisome details on the one hand, nor 
 unentertaining by reason of paucity on the other. No effort has been spared 
 to insure thoroughness, freshness, and perspicuity. The development of the 
 
 TiyoCOPitoRtCtlVED. 
 
 subject is clear and logical ; the scope of the work, comprehensive. Great 
 care has been exercised in the selection of material both for text-matter and 
 illustration, to give prominence to the striking and unusual, without sacri- 
 ficing the fundamental. Suggestive questions, not intended to supersede 
 minute examination by the teacher, are scattered through the text ; and an 
 intimate acquaintance with the maps is secured by a variety of questions fur- 
 nished with each, and requiring repeated reference on the part of the pupil. 
 
 The views of scientific students in regard to vulcanology and earthquakes 
 are presented, together with several illustrations of these phenomena. The 
 theory of ocean-currents is clearly unfolded in the light of modern discover- 
 ies. The subject of climate receives peculiarly full and interesting treatment, 
 as also that of clouds and precijjitation. The general motions of the atmos- 
 phere are made plain by the application of Ferrel's Law; while the theory and 
 movements of cyclonic storms are thoroughly considered and explained. The 
 chapters devoted to geology, botany, zoology, and ethnology, will be found 
 as fascinating as they are instructive. The text is lively and readable through- 
 out, and calculated to insjjii'e the pupil with a taste, if not enthusiasm, for 
 further pursuit of the study. 
 
 The value of the work is enhanced by the introduction of an ample bib- 
 liography of the subject. From their experience in the class-room, the au- 
 thors have been led to anticipate the wants of both pupils and teachers, and 
 have therefore incorporated in the text frequent references to standard mono- 
 graphs. These references are not made to supply omissions, but simply as 
 guides for those readers who may desire fuller and more satisfying information. 
 
 The pictorial illustrations, introduced not as embellishments alone, but 
 also as aids in imparting practical information, are based on original paint- 
 ings, photographs and objects selected in actual travel, and sketches made 
 both in this countrj' and Europe by specially qualified designers. Woodward, 
 J. C. Beard, Redwood, Fenn, Davidson, Cary, and Warren, furnished the 
 originals, in accordance with the in.structions of the several authors ; the 
 botanical subjects were drawn from specimens in the Torrey Herbarium, 
 Columbia College, by Arthur Hollick, Ph. B. 
 
 The maps, drawn by Mr. Jacob Wells, and engraved by Struthers, Servoss 
 & Co., of New York, have been constructed under the supervision of the 
 special authors, from the latest and most accurate information. The charts 
 of the Gulf of Mexico and the Caribbean Sea were furnislied by Commander 
 Bartlett himself. In the map of Alaska are recognized the discoveries of 
 Lieutenant Schwatka, Professor Libbey, and of later explorers, as well as 
 those relating to the physiography and hydrography of the northern portion 
 of the territory explored by Lieutenant Stoney. On the map of the Arctic 
 Ocean and North Polar Regions will be seen the location of Dr. Nanseu's far- 
 thest north. Particular attention is directed to the Relief Maps and profiles, 
 which are unsurpassed by anything of the kind hitherto published. 
 
 The physical features of the United States receive especial consideration 
 in the concluding chapter, which is embellished by a relief-map and a colored 
 physical map of our country, reflecting the highest perfection of the engrav- 
 er's art. The publishers trust that its unique and valuable features will rec- 
 ommend this work to the teachers of our grammar-schools, high-schools, and 
 colleges, as a progressive text-book, on a level with the present state of sci- 
 ence, and in full harmony with the requirements of the age. 
 
 H955 
 
 LIST OF MAPS. 
 
 Map of Isogonic Lines 
 
 Map of Isoclinal Lines .... 
 
 Geological Map of the World . 
 
 PriYSIOGRAPHT ...... 
 
 Bermuda Islands and Coral Reefs . 
 Volcanoes and Seismic Areas 
 Continental Drainage and Ocean-Cur- 
 rents ...... 
 
 The Gulp of Mexico . . . . 
 
 PAGE 1 
 
 
 8 
 
 
 9 
 
 13, 
 
 13 
 
 20, 
 
 31 
 
 
 31 
 
 38, 
 
 39 
 
 50, 
 
 51 
 
 
 53 
 
 The Arctic Ocean and North Polar 
 
 Regions ...... 54 
 
 The Antarctic Ocean and Continent . 55 
 Chart op Co-tidal Lines ... 58 
 
 The Caribbean Sea 60 
 
 Isotherms and Climatic Zones . . 66, 67 
 July and January Isobars ... 68 
 Wind-Zones and Periodic Rains . 73, 73 
 Map of Mean Annual Rainfall . . 80 
 
 Plants and Plant-Zones. 
 Distribution of Animals 
 Ethnology ..... 
 
 Distribution of Metals and Precious 
 
 Stones ...... 
 
 Geological History of the North 
 
 American Continent . 
 Physical Features op the U. S. 
 Alaska ,,...= 
 
 PAGE 
 
 94, 95 
 
 104, 105 
 
 113 
 
 118, 119 
 
 123 
 
 138, 129 
 
 133 
 
 NOV 22 189b 
 
 Copyright. 1687, by D. APPLETON AND COMPANY. 
 Copyright, ISas, by AMERICAN BOOK COMPANY. 
 
 'B'v-o ^-Vx^^'^''^^ 
 
LOCKWOOD ISLAND. 
 
 '--^^j^eHE E fi 1^1 V E R. E U T T E S 
 C0l.0R,ADO, 
 
 On The ZAMBESI. 
 
 SUBJECTS OF GEOLOGICAL AND GEOGRAPHICAL SCIENCE. 
 
 Geography is a description of the eartli on which we live. 
 As a science, it relates chiefly to the present surface of the earth. 
 It treats, also, of the earth as a whole, and of its relations to the 
 sun ; of the atmosphere that surrounds it ; of the plants, arunials, 
 and minerals, distributed through its different parts ; and of the 
 divisions made by man, each having its industries, institutions, gov- 
 ernment, etc. 
 
 Geology is the ancient history of the earth. It is the science 
 which determines the chronological succession of the great forma- 
 tions of the earth's crust, and investigates the causes of its present 
 surface features ; it further treats of the materials composing the 
 earth's substance, and of the development of life upon our globe as 
 recorded in its rocky framework. 
 
 These two sciences are so closely related that a thorough ac- 
 quaintance with one implies at least some elementary knowledge 
 of the other. 
 
 Geography is divided into three branches : Mathematical, 
 
 Political, and Physical. 
 
 Mathematical Geography ti-eats of the form and size of 
 the earth, its motions and their results, the modes of determining 
 nosition on its surface, and the methods of representing the earth 
 in whole or in part. 
 
 Political Geography treats of the earth's surface as occu- 
 pied by man, and divided l)y him into different countries ; and of 
 its inhabitants as regards their occupations, social condition, re- 
 ligion, and government. 
 
 Physical Geography, the subject of this volume, treats of 
 the natural divisions of land and water without reference to politi- 
 cal organization ; of the atmosjihere and climate of the earth, and 
 the causes that are implied in present changes upon its surface ; of 
 its vegetable and animal life, and the distribution of such natural 
 products as are of interest to man. 
 
 Physical geography is tluis a comprehensive science that in- 
 cludes applications from astronomy, the science of bodies in space ; 
 from geology, the science of one of these bodies especially — the 
 earth ; from physics, the science of the laws and properties of 
 matter ; from botany, the science of vegetable life ; from zoology, 
 the science of animal life ; from mineralogy, the science relating 
 to a large class of natural objects that have not life. 
 
 In the following pages it will be assumed that the student has al- 
 ready some knowledge of mathematical and political geography. The 
 subject of mathematical geography \\nll be bi-iefly reviewed for the pur- 
 pose of applyuig its principles to physical geography. An outline of 
 geology will also be given. For an explanation of the technical terms 
 which follow, the pupil is referred to the introductory paragraphs in 
 Appletons' "■Higher Geography.''' 
 
APPLICATIONS FROM MATHEMATICAL GEOGRAPHY, ASTRONOMY, AND PHYSICS. 
 
 THE EARTH AS A PLAMET. 
 
 Tlie Stars. — -The Sun is one of a multitude of Stars that 
 are continually giving out their energy, manifested chiefly as light 
 and heat, into space. It appears larger and brighter than the 
 others only because it is much nearer to us than they. 
 
 Probably' all the stars are in rapid motion, but as this is imper- 
 ceptible on account of their great distance, they are called fixed 
 STAus. They appear grouped in constellations. 
 
 The distances of the fixed stars from the Earth are so great as to 
 be inconceivable. The average distance of the Sun is nearly 93,000,000 
 miles. Light travels through space at the rate of 186,360 miles per 
 second, and therefore consumes more than eight minutes in reaching 
 us from the Sun. The time requii'ed for the passage of light from the 
 nearest fixed star to the Earth is estimated to be four and a third years ; 
 and from the more distant stars that are visible through the telescope, 
 many thousands of years. 
 
 TJie Stars are Self-luminous. If we assume them to be like 
 our Sun, each- must be a hot, dense body,, surrounded by a less 
 hot but still glowing atmosphere. Many are grouped in clusters 
 amid clouds of burning matter. Such clouds are called Nebula. 
 Herschel discovered nebulse whose light he estimated to have trav- 
 eled three million years before reaching our world. (On the Stars 
 and ISTebulffi, consult Lockyer''s '■^Elements of Astronomy^'' ^. ^5.) 
 
 The Solar System. — Many stars are attended by smaller 
 bodies which revolve around them.^ The name Solae System is 
 applied to a group consisting of the Sun and a vast but unknown 
 number of bodies revolving around it. The largest of these are 
 called Planets (from a Greek word meaning wanderer). 
 
 The Primary Planets, in the order of their distance from the 
 Sun, are-: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, 
 and Neptune. Some of these are attended by smaller bodies, called 
 Secondary Planets, or Satellites, which revolve around their 
 primaries while these are revolving around the Sun. The Earth 
 has one satellite, called the Moon ; Mars has two ; Jupiter, five ; 
 Saturn, eight; Uranus, four; and Neptune, one. 
 
 The path described by a body in its revolution around another 
 is called its orbit. Between the orbits of Mars and Jupiter are 
 
 many small bodies called Planetoids, which revolve about the 
 Sun. About 340 of these have thus far been discovered. 
 
 The planets with their satellites, and the planetoids, shine by light 
 reflected from the Sun, and are therefore comparatively cold bodies. 
 Jupiter, Saturn, Uranus, and Neptune, are probably feebly self-lumi- 
 nous, but far less hot than the Sun. 
 
 Comets and Meteors also belong to the solar system. 
 
 Growth of the Solar System. — According to the Nebu- 
 lar Hypothesis, which was generally accepted \y^ astronomers as 
 probably true, the matter composing the solar system was once 
 irregularly diffused in space as a great nebula, whose particles were 
 mutually attractive. They tended, therefore, to collect at the 
 center, and in so doing to give a whirling motion to the mass. 
 
 When the energy of motion is arrested, it is changed into that of 
 heat and light, as is familiarly shown in heating a piece of iron by hain- 
 mering. The dense but still nebulous mass, with its particles falUng to 
 the center, became hottest there, as the speed of rotation increased. This 
 increase of speed in turn developed an increased tendency to fly ofl: from 
 the center, just as the mud is thrown from a rapidly -revolving wheel. 
 The disk, therefore, became separated into a series of rings, with the 
 greater part of the mass still rotating at the center, its temperature in- 
 creasing until it was compressed nearly to the present size of our Sun. 
 
 Each ring continued to contract until its particles were aggregated 
 into a hot sphere, rotating on its own axis and at the same time revolv- 
 ing around the central hot sphere. The heat due to contraction was 
 continuously radiated into space, slowly from the larger masses and rap- 
 idly from the smaller ones. Thus were formed the Sun and its Planets. 
 
 Some of the planets in contracting threw oil secondary rings, and 
 these condensed into satellites like our Moon. 
 
 Whether or not the original foi'm of matter was gaseous, recent 
 researches seem to indicate that the heavenly bodies had their immedi- 
 ate origin in the gradual contraction of masses of meteorites. True 
 NebulEe are clouds of meteorites in collision and process of condensa- 
 tion. They will grow hotter and brighter as the collisions increase in 
 frequency and violence, and it is believed will ultimately condense into 
 suns. 
 
 Whichever hypothesis be accepted, our Earth is a cooling body 
 that is still rotating on its axis and radiating forth the heat due to 
 its condensation. It would naturally cool most rapidly at the sur- 
 face, become most dense at the center, and continue to contract as 
 long as it gives out heat. Its surface would become hard, and 
 wrinkled into folds as it settled upon the contracting interior. 
 
 SIZE AMD FORM OF THE EARTH. 
 
 The Earth is not quite spherical in form. The distance from 
 North to South Pole is 7,899.17 miles. Its mean diameter at the 
 Equator is 7,925.65 miles, or 26.48 miles in excess of the polar 
 diameter. The form of the earth is very nearly that of an oblate 
 spheroid. 
 
 There is reason to beheve that the Equator is not an exact circle, 
 and that no meridian is an exact ellipse. Nevertheless, the Earth 
 is so nearly a sphere, that for most purposes it may be regarded as 
 such. Its circumference at the Equator is 24,899 miles ; its surface, 
 not quite 197,000,000 square miles ; and its volume, 260,000,000,000 
 cubic miles. 
 
 The Earth's deviation from perfect spherical form is trifling in 
 comparison with its size ; if a globe twelve inches in diameter were 
 flattened in the same proportion, no eye could detect the change. 
 
THE EARTH AND THE OTHER PRIMARY PLANETS. 
 
 In speaking' of the form of the Earth, the inequalities of its surface 
 are not considered. The highest mountain has an elevation of only 
 five and a lialf miles, and if proiwirtionately represented on a twelve- 
 incli globe, would be no larger than a grain of sand. 
 
 COMPAKISOM OF THE EARTH WITH OTHER MEM- 
 BERS OF THE SOLAR SYSTEM. 
 
 The Volume of the Sun (its euhical contents, or size) is 
 over 1,300,000 times that of the Earth, while its mass ((jiiantity 
 of matter) is 3?)0,000 times as great. Its surface is composed 
 of exeeedino;ly hot and brilliant clouds, wliich contain in a "ahq- 
 ous condition many of the substances that exist here in a solid 
 state, such as iron, lead, nickel, and zinc. Its l)odj is believed to 
 be not solid, but gaseous ; a ball of ga.s, probably one hundred 
 times denser than any gas known upon the Earth. At a distance 
 of 93,0n(>,00ii miles, it is now giving to us almost enough heat to 
 balance that which the Earth is losing by radiation. 
 
 Tlie cloudy envelope surrounding the Sun is subject to violent 
 storms. Masses of hot gas are ejected to the height of many thousands 
 of miles, and dark spots mark the areas of greatest distui'bauce. The 
 solar surface is rarely free from spots. Their frequency increases or 
 diminislies from year to year, periods of greatest frequency occurring 
 once in ten or twelve years. 
 
 The Sun. 
 (From Ilai'varil College Observatory drawing.) 
 
 By the use of appropriate instruments, astronomers have ascertained 
 the composition of the Sun's sm-face-elouds. About one-third of the 
 elements known to compose the Earth's surface have been discovered in 
 them. (On the Sun and Planets, consult PecKs '^Popular Astronomy," 
 p. 135.) 
 
 Jupiter and Saturn are hot bodies, whose surfaces are 
 covered with thick masses of cloud that appear to be self-luminous 
 as well as to reflect the light of the Sun. In form they are much 
 more oblate than the Earth, and their density is less than that of 
 the Sun. If we adopt the Earth's mass as a unit, that of Jupiter 
 is 312, that of Saturn 93 ; but desj^ite their great size, these planets 
 rotate more than twice as fast as the Earth. Jupiter has five sat- 
 ellites. Saturn is inclosed within a series of rings, around which 
 its eight sateUites revolve. Like the Sun, these two planets appear 
 to be masses of dense, hot fluid. 
 
 Mars in 1862. 
 
 The surface of Mars is diversified with what are believed to 
 be bodies of land and water. It has an atmosphere in which 
 clouds float, and its polar regions are white with what appears 
 to be snow. Its mass 
 is aboTit one-ninth of the 
 Earth's ; and its body is 
 proljably solid through- 
 out. 
 
 The Moon's sur- 
 face is greatly folded and 
 cracked, and presents no 
 evideuee of having any 
 gas or even water left 
 upon it. It gives out 
 little or no perceptible 
 heat, aside from that 
 which it receives from 
 the Sun. The Moon is 
 beUeved to be solid to 
 its center, and to have 
 
 radiated already nearly all the heat due to condensation. Its sur- 
 face temperature is not known, but can be very little above that 
 of surrounding space, which is estimated to be al)0ut 490° Fahr. 
 below the freezing-point of water. 
 
 (On the Moon and Lunar Scenery, con.mlt Nasmyth and Carpen- 
 ter''s " The Moon, as a Planet, a World, and a Satellite.") 
 
 Of surface conditions on Uranus, Neptune, Venus. Merenry. 
 and the Planetoids, nothing definite is known. Meteoric Bodies 
 which enter our atmosphere and fall u]5ou the surface of the 
 Earth are found to consist of well-known materials. The Nebula^, 
 aud some of the Stars, are composed of elements like those iu the 
 atmosphere of the Earth and Sun. 
 
 The condition of the Earth is apparently intermediate between that of 
 .Jupiter and tliatof Mars. Its interior is still intensely hot, aud although 
 there is reason to believe much of it to be solid, or at least exceedingly 
 dense, there are subteri'anean regions of softness, where the hot material, 
 if not liquid, is viscous like tar. The surface is hai'd and much folded, 
 and is still slowly couti-aeting. No satisfactoi-y estimate can be made of 
 the millious of centuries that have elapsed since the Earth first assumed 
 the liquid form, or of the time that has intervened since its crust became 
 rigid, or since the temperature of the oceans that fill its surface depressions 
 equaled the present temperature of boiling water. There is much reason 
 to believe that its fu-st living inhabitants made theu- home in hot water. 
 
 The Earth is thus seen to be only one of a multitude of bodies in vari- 
 ous stages of planetary development, the rapidity of which is regulated 
 by their size. It is now temporarily in a state adapted to the existence of 
 such animal and vegetable life as we are familiar with. The Sun, Jupi- 
 ter, and Satm'u, have not yet reached this stage ; Mars aud the Moou 
 appear already to have passed it. 
 
 THE EARTH'S MOTIOMS. 
 The Earth has two motions — a daily and a yearly motion. 
 
 Daily (Diurnal) Motion. — The Earth, as we have seen, 
 turns on its axis. One rotation is completed in a period which we 
 call a day, and divide into twenty-foitr hours. 
 
 But the term day is used iu another sense, as opposed to night. 
 The Earth receiving: its liirbt from the Sun, it is day on that half 
 of the Earth's surface which is pre-sented to the Sun : the oppo- 
 site half is iu darkness or night. The Earth's rotation is con- 
 
THE CHANGE OF SEASONS. — MAGNETISM. 
 
 stantly whirling new places into light (causing sunrise to them) 
 and sweeping others into the shadow (causing sunset). It thus 
 produces the Succession of Day and Night. 
 
 The great circle which separates the lighted side of the Earth 
 from the dark side is called the Circle of Illumination. (Trace 
 it on the spheres in the accompanying diagram.) 
 
 Yearly (Annual) Motion. — "While the Earth is tm-ning on 
 
 its axis, it is also revolving in its orbit or path around the Sun. 
 One revolution is completed in a period which we call a year, and 
 which is equal to about 365J days. 
 
 The Earth's yearly revolution is perfoimed with its axis i?i- 
 dined to the plans of its orhit and always pointing in the same 
 general direction; to this fact is due the Change of Seasons. 
 The direction in which the Sim's rays strike any part of the Earth's 
 surface is continually changed, and with it the amount of heat re- 
 ceived ; for the more nearly perpendicular the rays ai'e, the more 
 heat they impart. 
 
 The above diagram sliows the Earth at four points of its orbit. In each, 
 the axis N S is inclined to the plane of the orbit (deviating from tlie perpen- 
 dicular about 33^°), and points in the same direction. (The Earth's axis does 
 vai-y in direction, but the change takes place so slowly as to be imperceptible, 
 except with the most delicate instruments.) 
 
 At a, the Earth's position on June 21st, the North Pole is tiu-ned toward the 
 Sun. The inclination of the axis being 23^°, the Sun's rays are now perpen- 
 dicular at places on a line 23i° north of the Equator; the Sun at noon is here 
 directly overhead. This line, from the fact of the Sun's appearing to turn 
 south after reaching it, is called a Tropic {turning-line), and it is distinguished 
 as the Tropic of Cancer. Summer now reigns in the north, winter in the 
 south. The circle of illumination {refer constantly to the diagram) extends 
 231" on the opposite side of the North Pole, and there fixes the position of 
 what is called the Arctic Circle. Regions north of the Arctic Circle remain 
 within the circle of illumination notwithstanding the rotation of the Earth, 
 and hence have a day more than twenty-four hours long. Regions near the 
 South Pole are not brought within the circle of illumination by the Earth's 
 rotation, and hence have a night more than twenty-four hours long. 
 
 In three months the Earth reaches 5 (September 22d). The Sun's rays are 
 now perpendicular to the Equator, and days and nights are everywhere equal ; 
 'this is the period of the northern autumn and the southern spring. 
 
 Three months more bring the Earth to c (December 21st). The conditions 
 of the position at a are now reversed. The South Pole is turned toward the 
 Sun, whose rays are perpendicular to places on a line 23J° south of the Equa- 
 tor. The Sun appears to turn north after reaching this line, and this turning- 
 line is distinguished as the Tropic of Cap'ricorn. The south has its 
 summer, the north its winter. The circle of illumination extends 23^° on the 
 opposite side of the South Pole, and fixes the position of what is known as 
 
 the Antarctic Circle. South of the Antarctic Circle the day is more than 
 twenty-four hours long, while north of the Ai'Ctic Circle the night is more 
 than twenty-four hours long. 
 
 Still moving east, the Earth, on March 20th, reaches d, where the light 
 once more spreads from pole to pole, and day and night are each everywhere 
 twelve hours long. The solar rays are now again perpendicular to the Equa- 
 tor, and slant equally at the two tropics. Spring prevails in the north, au- 
 tumn in the south. Observe that on the Equator the Sun is never far from 
 the zenith, and we have perpetual summer. 
 
 Questions. — Into what inquii'ies connected with the Earth does geography 
 enter ? Geology ? Explain the relation existing between these two sci- 
 ences. What does physical geography teach, and how does it necessarily 
 include applications from other departments of physical science ? 
 
 What are Stars ? Why does the Sun appear larger and brighter than the other 
 Stars? To what is the brightness of the Stars due? Give an idea of 
 their distance as measured by the velocity of light. Describe the various 
 bodies composing the planetary system of which the Sun is the center. 
 What important difference is there between the Planets and the Sun ? 
 Account for the formation of the Solar System according to the Nebular 
 Hypothesis. What can you say of the Earth's past condition, and of its 
 present state and form ? Compare it with the Sun and its sister Planets in 
 respect to size, density, and stage of development. State what is known 
 of the Moon. 
 
 How many and what motions has the Earth ? Explain the phenomena of day 
 and night. Describe the Earth's yearly motion. What proof can you 
 give of its annual revolution ? To what extent are its movements felt by 
 its inhabitants ? 
 
 THE EARTH'S MAGMETISM. 
 
 Natural Magnets. — In various parts of the earth an ore of 
 iron is found which has the property of attracting iron. It is 
 called magnetite, or lodestone, and was known to the ancients, 
 occurring near Magnesia, a city of Asia Minor. A ny body which 
 has this property is called a Magnet. 
 
 Artificial Magnets. — If a bar of steel be sufficiently rubbed 
 against a natural magnet, it assumes a magnetic condition, and is 
 called an artificial magnet. There are also other methods of pro- 
 ducing artificial magnets. 
 
 Steel when once magnetized gives up this condition very slowly. A 
 piece of ordinary soft iron receives and gives it up very quickly. The 
 difference between permanent and temporary magnets is only one of 
 degree. No artificial magnet retains its power permanently undimin- 
 ished, or acquires it instantaneously. 
 
 Magnetic Polarity. — If a magnetized steel bar be buried 
 
 in filings of soft iron and then withdrawn, these will cling to it 
 thickly about the two ends, and usually not at all at the middle. 
 Two points, one near each end of 
 the magnet, are called its poles. 
 
 (The teacher should give experimental 
 illustration of the fundamental facts of 
 magnetism.) 
 
 The Magnetic Meridian. — When a bar magnet is proper- 
 ly suspended, or balanced on a pivot, it assumes a definite direction 
 called the magnetic meridian. This is nearly, or may be quite, 
 north and south. The pole which points northward is called the 
 north-seeking, or positive pole ; the other is the south-seeking, or 
 negative pole. They may be designated as the + pole and the — 
 pole. 
 
 When the -f- pole of one magnet is brought near the + pole 
 of another, they mutually repel ; but if the + }>ole of one ig 
 brought near the — pole of the other, they mutually attract. 
 
 Magnet dipped in Filings. 
 
MAGNETIC ELEMENTS. —MARINER'S COMPASS. 
 
 TiiK Magnetic >Si'Kciiu.m, ^iiowi.nu Li>h.i ut l''oia:b,. 
 
 Maj?iH'ii<r IiuliK'tion. — If cither pole of a ma<rnet he 
 l)r(iiight near to a pieci' ol iron, the iron hec(jnie.s for tlie time 
 niaguetic, with its -j- pole nearest the — pole of the first magnet; 
 if free to move, the iron will he drawn towiird the mamiet. Mag- 
 netisni thus excited is said to be huluced. Induction is not pre- 
 vented by intervening bodies which are not themselves magnetic. 
 
 Lines <)f Force. — If upon a horizontal bar-magnet a plate of 
 glass be rested, and iron tilings scattered ovei' it, the tilings, when 
 tlie glass is gently tapped, become arranged by induction in })ecul- 
 iar curves, called lines of magnetic foi'ce. The space within wliich 
 these lines may be thus jiroduced is called the ma<jnetw Jidd. A 
 magnetic body always tends to jilace itself along the line of 
 force that passes through it. {Consult A Lecture on Magnetinni, 
 in Professor TyndaWs ^'- Fi'agments of Science.'''') 
 
 The Eaitli 
 a Great Maj?- 
 
 iiet. — The fact 
 that a magnetized 
 needle jtlaces it- 
 self in the mag- 
 netic meridian 
 shows that the 
 earth acts as if it 
 contained a great 
 magnet, some of 
 whose lines of 
 force pass along 
 the ground in cer- 
 tain places and 
 penetrate it in 
 
 others. A terrestrial — ^ ]iole must be in the neighborhood of the geo- 
 graphical Xortli Pole, in order to attract the + pole of the ueedle. 
 
 Thus, in the accompauyiiif!; figure, if the great maguct be represented to 
 have its -t- pole at p and its — pole at «, its lines of force will be represented 
 by the curves. One of these passes along the earth's surface at a ; others cut 
 
 it at ?), c, d, e, J\ and g. 
 a The + poles of the nee- 
 
 dles at a, A, c, d, are all 
 turned toward the geo- 
 graphical North Pole 
 N ; the needle at u is 
 parallel to the earth's 
 surface ; those at b and 
 care inclined, witli their 
 -1- poles dipping toward 
 the ground ; that at d 
 is vertical, with its + 
 pole toward the ground. 
 Those at e and f dip 
 with their — poles to- 
 ward the ground and 
 pointing southward, 
 while that at </ is ver- 
 tical, with its — pole 
 toward the ground. Many of the lines of force arc entirely within the earth. 
 {Refer to DesehiiiifVn •' N(ttiir<il P/iihmj/h;/,''^ pj). BoS-OGS.) 
 
 The diagram expresses an ideal case ; the reality is not ijiiite so sinii)!e. 
 
 Magnetic Elements. — The magnetic needle does not 
 generally ]>oint exactly toward the true north. The angle 
 between the magnetic meridian and the geographical meridian 
 is called the angle of (/ecluiatio/i. If a needle be balanced so 
 as to be horizontal when suspended by a thread, and then be 
 
 LisEs OF Terrestrial Magnetic Force, 
 
 magnetized, it will not only place itself in the vertical plane 
 of the magnetic meridian, but will assmiie a particular direc- 
 tion in that plane, usually inclined at 
 a considerable angle to the horizon. 
 This angle is called the dij), or in- 
 clination. In the northern hemispliere, 
 the north pole of the magnet dips; 
 in the southern hemisphere, the south 
 pole. 
 
 The force exerted by the earth-magnet 
 upon the needle is not the same at all 
 l)laces. The measure of this force upon 
 a unit magnet pole is called the intensity. 
 
 Thus, iu the figure opposite, the dip and intensity at c are greater 
 than at 5, because c is nearer to n. The declination, dip, and in- 
 tensity, constitute the magnetic elements of a place. 
 
 The Mariner's Compass. — The tendency of the needle 
 to seek a north-and-south line led to the practical application of 
 magnetism by na\igators. The Mariner's Compass consists of one 
 or more magnetic needles attached to the lower face of a circular 
 card, which is delicately pivoted and generally immersed in a 
 licpiid, so as to decrease the pressure upon the pii^'ot. The cir- 
 cumference of the card is divided into degrees and also into 
 thirty-two " points of the compass." It is suppoi-ted in such a 
 manner that the card may always be horizontal, notwith-standing 
 the motion of the vessel. The needles remain in the magnetic 
 meridian, with which a ship's course may readily be compared. 
 
 The Mariner's Compass was, according to some authorities, invented in 
 China, and made known to Europeans through the instrumentality of the 
 Mohammedan Arabs. The first mention of the use 
 of the magnetic needle in Christian Europe oc- 
 curs in a curious Provcnyal poem, written iu 1190. 
 Early accounts of the instrument describe it as a 
 simple iron needle, magnetized and placed on a 
 pivot, or floated on a cork in a vessel of water, in 
 either case free to turn in any direction. It was 
 observed that a needle thus treated came to rest in 
 an approximately north-and-south line, early com- 
 passes presumably being very inaccurate. A cross- 
 piece is thought, in some instances, to have been 
 affixed to the needle, for the purpose of determining 
 the cardinal points of east and west. This rude 
 instrument served equally well to guide the traveler 
 over the deserts of Central Asia and the Chinese 
 sailor through the southern seas. 
 
 A knowledge of magnetism, and of its practical 
 application in the compass to determine diiections, 
 stimulated that thirst for maritime discovery which 
 marked the transition from mediaeval to modern 
 times. It was nut until the fifteenth century that voyages were confidently 
 prosecuted by European navigators on a systematic plan, and Portugal and 
 Spain laid the foundations of those vast colonial empires that were at once 
 the admiration and envy of the world. 
 
 The declination of the compass-needle, known in Europe in the thirteenth 
 century and independently discovered by Columbus in 1482, was noticed in 
 an English publication of the sixteenth century, entitled "A discourse on the 
 variation of the Cumpas or Magneticall Needle." The dip of the needle was 
 discovered accidentally in 1576 by an English instrument-maker, who found 
 the inclination at London to be 71° 50'. 
 
 Isogonic Lines. — The declination of the compass-needle at 
 any place may be found by comparing its direction with that of 
 the north point of the heavens, which is close to the polar star. 
 U])on a chart of the world, lines may be drawn connecting places 
 which have equal declination. These are called Isogenic Lines. 
 
 Dip or Inclination. 
 
LINES OF EQUAL MAGNETIC VARIATION. 
 
 Refer to the Chart of Equal Declination above. It will he seen that on a 
 line passing through Ohio, Kentucky, North Carolina, Guiana, and Brazil, 
 the declination is 0°; hence, at any point of this line the compass-needle 
 points to the true north. Such a line is called an agonic line. Immediately 
 on the east of this line, the needle points west of north. This error increases 
 as we go farther northeast, and then north and west. In Bafinn Bay, the 
 declination is 90° west, in Grinnell Laud the + pole of the needle points to 
 the southwest, and at a place in Melville Sound it points due south. As we 
 pass toward Europe, the declination, though still westward, diminishes until 
 it becomes 0° along a line passing through Russia, Persia, and Australia. 
 Beyond this line, the declination becomes increasingly eastward until it is 20° 
 east at the mouth of the Yenisei River. It then diminishes until it becomes 
 0° again along an oval line inclosing the Japan Islands, and parts of the 
 Chinese Empire and Siberia. Within this oval the declination is westward. 
 Beyond it, the declination becomes again increasingly eastward, reaching 90° 
 east in the Arctic Ocean near Banks' Land. The + pole of the needle then 
 points southeast until it reaches the place in Melville Sound where it points 
 due south. 
 
 This behavior of the magnetic needle seems to indicate that, 
 instead of a single focus of negative magnetic sti-ength beneath the 
 Arctic regions, there are two such foci, the stronger of the two 
 being under North America, and another of the same kind under 
 Siberia. Corresjionding to them there should be a pair of positive 
 magnetic foci beneath the Antarctic regions. The earth's mag- 
 netic system has long been believed to have four poles. 
 
 Isoclinal Liiies. — The lines connecting places which have 
 equal magnetic dip are called Isoclinal Lines. The line along 
 which there is no dip is the Magnetic Equator. 
 
 Refer to the Chart of Equal Dip, on page 9. It will be seen that 
 the magnetic equator does not coiucide with the geographical equator, but 
 cuts it about longitude 6° west and 168° west, passes farthest south near 
 the point where it crosses the American line of no declination, and 
 
 farthest north near where 
 it crosses the European 
 line of no declination. 
 The u-regularity of the 
 
 isoclinal curves is not so striking as that of the isogonic curves. As we 
 l)ass north vs^ard from the magnetic equator, the dip increases untU the + 
 pole of the needle points vertically downward at a place in Boothia Pen- 
 insula whose position in 1884 was latitude 70° 30' north, longitude 96° 
 40' west. This is called the j^o^^ of verticity, or often simply the mag- 
 netic pole. The position of the southern pole of verticity is estimated 
 to be about latitude 73° 30' south, longitude 147° 30' east. {See Balfour 
 Steu-arfs article on ''Meteorology,'" Encyclopaedia Britannica.) 
 
 Magnetic Intensity. — The intensity of the eai-th's mag- 
 netic force is not the same for all places of equal dip. 
 
 The stronger, or American, focus of greatest intensity is esti- 
 mated by Sir Frederick Evans to be in latitude 52° north, longi- 
 tude 90° west, beneath the area between Lake Superior and Hud- 
 son Bay ; and the weaker, or Siberian, focus at latitude 70° north, 
 longitude 115° east, beneath the marshy region between the Yeni- 
 sei and Lena Rivers. At the pole of verticity, therefore, which is 
 between these two foci, the -j- pole of the needle is unequally 
 attracted by both. The soiithern foci are supposed to be close to- 
 gether, between Australia and the Antai-ctic Continent. 
 
 Variation of the Magnetic Elements. — The magnetic 
 elements are subject to slight daily and annual valuations, and to 
 variations extending through long periods of years. 
 
 The American line of no declination in 1790 passed through Norfolk, 
 Vu'ginia, where the declination is now (1886) more than 3° west. At 
 New York the declination in 1686 was 9° west; in 1750, 6° 20' west ; in 
 1790, 4° 15' west ; in 1847, 6° 30' west ; in 1885, 8° west. This indicates 
 that the American magnetic focus moved eastward *roni 1686 to 1790 
 
LINES OF EQUAL MAGNETIC DIP. 
 
 tli3u became stationary, and ]ias ^iiice been moving westward. Still 
 greater variation lias been recorded in Loudon and Paris. 
 
 Tlie Cause of the earth's magnetism, and of the variations no- 
 ticed, is imknown. Violent and sudden variations, called magnetic 
 storms, take place at times. They occur simultaneously with distiu-b- 
 ances on the surface of the sun. The outbreak of a large sun-spot iu 
 1882 was followed by a magnetic storm of such violence in the United 
 States as to interfere seriously with telegraphic communication. 
 
 Questions. — What is a magnet ? Explain magnetic polarity, and tlie law of 
 magnetic behavior. What are the magnetic poles of the earth ? Describe 
 the mariner's compass. What is meant by the declination of the needle ? 
 The dip ? Magnetic intensity ? What are isogonic lines, and what is the 
 position of the lines of no variation on the earth ? Define isoclinal lines. 
 What is the magnetic equator ? Find the present declination at New 
 York; San Francisco; Tokyo; London. To what variations are the mag- 
 netic elements subject ? E.xplaiu magnetic storms, and their effects. 
 
 
 
 
 
 •I .V ^'iV^ *^.- -I 
 
 "^ <^ T\ Z c\ O C e\a at »NTABcr, ^ 
 
 THE WOKLD ['""{'"^^r^, 
 
 MERCATOR'S PROJECTION ; i j I I I ■ '^^ 
 
 MODES OF EEPEESEJVTIJYG THE EARTH'S SUEFACE. 
 
 Globes and Mai>S are used to represent the earth's surface. Globes repre- 
 sent the wUule surface in its own spherical form; maps represent cither the whole or 
 part, and on a flat surface or plane. 
 
 Meroator'.S Projection. — The maps in this volume arc principally on what 
 is called "llcrca tor's Projection." It represents the earth's surface exiianded as it 
 would have to W to coincide with tlic intciior surface of a hollow cylinder enveloping 
 the globe and touching it at every point of tlie equator. 
 
 The meridians are thus converted into parallel lines. The degrees of longitude, 
 instead of diminishing as we leave the equator, remain of uniform length. The de- 
 grees of latitude, instead of remaining of uniform length as we leave the equator, are 
 increased in the proper ratio. The consequence is, that the size of coimtries in high 
 latitudes, north or south, is greatly exaggerated ; as will be seen by comparing the 
 northern part of North America, as shown in the Mcrcator map above, with the repre- 
 sentation of the same iu the map of the hemispheres on a globular projection. Yet the 
 exact direction of one place from another is shown, and hence charts on Mcrcator'! 
 projection are used by navigators. 
 
STRUCTURE OF THE EARTH. 
 
 Geological Agencies. — The crust of the earth is that out- 
 ward jjortion of it which has cooled, hardened, and subsequently 
 become modified by various agencies. It is the province of geol- 
 ogy to explain to us of what that crust is made, and how it has been 
 formed. Among the agencies that have been most effective in 
 causing changes upon the earth's surface are its envelopes, air and 
 water. The friction of the air, which presses upon every square 
 inch of the surface with a weight of l-i.7 pounds, produces the 
 waves of the sea, and sweeps sand from place to place on the land. 
 The atmosphere also carries moisture, which is precipitated as i-ain 
 and snow ; rivers and masses of ice are formed, by the action of 
 wliich highlands are worn down and %'alleys excavated {see cuts, 
 pp. 56, 83). The material removed is transported to the sea- 
 basins, where it is deposited in sediments, which become, by eleva- 
 tion, new land. (On erosion by rain, rivers, and ice, consult Gei- 
 Jcl<^s ''Text-Bool of Geology," pj^. 3Jf3, 371, and US) 
 
 The waves of the sea, the most potent of geological agents, 
 dashing incessantly upon all shores, are constantly wearing away 
 the land and spreading in the rear of their line of advance the 
 materials which they grind up or take into solution. 
 
 Materials comi)osing the Earth. — The materials com- 
 posing the earth are called minerals. Water and air, with many 
 other gases and liquids, are to be regarded as minerals, since they 
 do not belong either to the animal or the vegetable kingdom. 
 
 Minerals, in their unerystallized condition and generally mixed 
 together, form Eocks. There are about twenty minerals which 
 may be considered I'ock-makers. Of these, silica is the most 
 abundant, since it constitutes about half of the minerals and rocks 
 known. When pure it is called quartz (rock-crystal, agate, flint). 
 Most gravel and sand is composed of quartz, which is so hard, 
 tough, and insoluble, that it remains in lumps and grains after the 
 minerals associated with it are ground up or dissolved away. Next 
 to silica, the most abundant minerals are the feldspars, generally 
 white or flesh-red in color, which when decomposed form clay. 
 
 Rocks may be divided into three classes — Igneous, Sediment- 
 ary, and Metamorphic. 
 
 Ig'iieoiis Rocks (from the Latin word ignis, meaning fire), 
 generally characterized by a crystalline or glassy structure, are such 
 as have been formed by fusion, or melting by heat. Some have 
 been ejected from volcanoes (obsidian, or volcanic glass) ; others 
 have cooled in great masses and solidifled beneath the surface (sy'e- 
 uite, sometimes called Scotch granite, quarried for monuments by 
 the ancient Egy])tians). 
 
 Sedimentary Rocks are those wliich have been deposited 
 from water. Some, like sandstone, have been made of fragments 
 transported from a distance, then deposited and consolidated ; 
 others, such as rock-salt and gypsum, have been deposited from 
 solution ; and others still (limestone, marl, and tripoli) are com- 
 posed of the remains of animals and plants. 
 
 Metamorphic Rocks (from the Greek word metamor- 
 phosis, change) are made up of sediments that have been changed 
 from their original condition by pressure, heat, or chemical action ; 
 they include the marbles. 
 
 Nearly all high, isolated mountaius are the remains of projecting 
 masses of igneous rock ; continuous mountain-systems and great ranges 
 are com.posed foi- the most part of metamorphic rock ; while low plains 
 consist of sedhueutary deposits. 
 
 
 Disturbed Strata on the Berwickshire Coast. 
 
 Strata.— Sedimentary material is found in layers, which are 
 called Strata. "When these are subjected to lateral compression 
 due to the contraction 
 of the earth's crust, they 
 become folded, and even 
 highly tilted and brok- 
 en. Metamorphic rocks 
 are always thus greatly 
 folded. 
 
 The softer parts of 
 strata, whether horizon- 
 tal or folded, are washed away in time by the action of rain, leaving 
 hills and valleys. The chai-m of bold mountain scenery is due to 
 inequalities produced by erosion of this kind. 
 
 Erosion and stratification are continually modifying the earth's sur- 
 face to-day as they have done in the past. The pi'ocess of stratification 
 is often noticeable on the sea-shore, where deposits are left by receding 
 tides and hardened in the sun. 
 
 Fissnres. — Faults. — Veins. — When strata break under 
 pressure from the sides, the openings thus produced are called Fis- 
 sures. Sometimes one wall of the fissure slides past the other, so 
 that the strata on opposite sides are unlike. The result is called a 
 Fault. 
 
 Such displacement in mountainous regions often amoimts to 
 thousands of feet. If the fissure becomes filled with rock material 
 
 afterward, this is called a 
 
 Vein. Most of the ores 
 which yield valuable metals 
 are found in veins. (On 
 stratified rocks, faults, etc., 
 consult Le Oolite's " Ele- 
 ments of Geology," p. 170.) 
 
 Soil. — All soil, except 
 the trifling amount due to 
 vegetable deposit, and such 
 as is formed by the deposit of mineral particles from air-cun-ents, 
 results from the gradual decay of rock under the action of atmos- 
 pheric agencies. The perfect gradation from soft surface-soil down 
 to hard rock may often be seen in railway-cuttings, excavations, 
 and quaiTies. 
 
 After the surface-rock has been broken up into soil, this is partly 
 washed off by rain, and hence is often found far away from the place 
 where it Avas produced. The harder detached masses left behind are 
 roughly rounded by the sm-face decay, and are called bowlders of disin- 
 tegration. The unchanged mass underlying tlie soil is distinguished as 
 bed-rock. 
 
 Surface- rock is always traversed by multitudes of fissures, par- 
 ticularly in places where there are great extremes of temperature. 
 Alternate ex])ansion and contraction under the vaiiation of heat 
 causes it to crack, and through these openings moist air and rain- 
 water gain access to great depths. The soluble material of the 
 rock is thus separated from the silica with which it has been asso- 
 ciated, and the solid mass crumbles into soil. Flinty rocks decay 
 slowly on account of the insolubility of silica. Granite and lime- 
 stone decay more rapidly. 
 
 In cold climates, frost is an important agent in disintegrating the 
 rocks. Water expands with irresistible force in freezing, and that wliich 
 percolates into the rock-fissures acts mechanically in splitting the rock 
 into fragments when the weather is cold. At the base of many clifl^s 
 
 Faulted Strata on Railway-Cutting near 
 tunbridge. 
 
GEOLOGICAL AG ES. — FOSSI LS. 
 
 11 
 
 lies a pile of loose broken stones, produced by the falling of masses that 
 liave been gradually separated under the agency of air, water, and 
 changes of temperature. (On the ett'eots of weathering, see Prestwich's 
 "Geology, Chemical, Physical, and Stratigrapltical," col. i, p. 152.) 
 
 GEOLOGICAL AGES. 
 
 Fossils. — Tlie buritn] remains of anim;il and veg;etable life 
 belonging to former agei5 are called Fossils (things dug). Fossils 
 include not onlj petrifactions — representing the actual portions of 
 organisms, like bones, wood, and bark — but also the traces of the 
 existence of plants and animals as indicated by the Ciists of shells, 
 the impressions of leaves, the footprints of various creatures, etc. 
 Rocks rich in such organic remains are known as fossiliferoiis. 
 The relative age of rocks, and often the conditions under which 
 they were formed, are determined by the natiu'e of their fossils. 
 
 The science which treats of the living beings that have inhabited the 
 globe at past periods of its history, investigates their natiu-e and dis- 
 tribution, and traces theLr relationship to existing species, is called PalcC- 
 outology {science of ancient life). 
 The principal fossils peculiar to the 
 dilfereut geological formations are 
 described in the following para- 
 graphs and illustrated on the Geo- 
 logical Chart, pp. 12, 13. (For full- 
 er infonnatiou on this subject, the 
 student is referred to Nicholson's 
 "Manual of Palaontologij,'''' and 
 Binney's "Fossil Plants.^') 
 
 Succt'ssiou ill Time. — 
 
 Careful study of the different 
 layers composing the earth's 
 crust, and of the fossils imbed- 
 ded therein, has shown geolo- 
 gists that they are arranged in a 
 chronological or time series, and 
 form groujis each of which is 
 characterized by its own set of 
 fossils. Special names have been 
 given to the great divisions; 
 thus, the oldest rocks known 
 have been called the Archaean 
 group (from a Greek word 
 meaning heginning) ; the next 
 is the Palicozoic {ancient lif<-) 
 group ; the third, the Mesozoic 
 {middle life) group; and the 
 fciurth, the Neozoic {neio life) 
 group. When used as divisions 
 of time, these names designate 
 Eras. 
 
 The subdivisions of these 
 great groups are known as Sys- 
 tems, and the time-intervals dur- 
 ing which they were deposited 
 are the Geological Ages. The 
 names of these have been de- 
 rived from the locahties where 
 
 the corresponding strata are found, or from certain characteristics 
 of the strata. For example, the Archaean rocks are divided into 
 two systems, Laurentian and Huronian — the first taking its name 
 from the St. Lawrence River, the second from Lake Huron. 
 
 Gboupb of Rooks. 
 EBiB OF Time. 
 
 Systems of Strata. 
 Geological An£B. 
 
 IV. Neozoic 
 
 III. Mesozoic. . . . 
 
 II. Palaeozoic. . . 
 I. Archaean. . . . 
 
 j Quaternary, 
 
 ( Tertiary. 
 
 ( Cretaceous, 
 -! Jurassic, 
 ( Triassic. 
 ' Carboniferous, 
 
 Devonian, 
 • Upper Silurian, 
 
 Lower Silurian, 
 _ Cambrian. 
 ( Huronian, 
 / Laurentian. 
 
 The names of the groups of rocks and the systems of strata 
 are presented in the following synopsis in tabular form : — 
 
 Archsean Era. — There is 
 no undispTited evidence of life 
 during this era. The earth had 
 cooled down to a temperature be- 
 low the boiling-point of water, as 
 shown by beds of stratified rocks, 
 greatly folded and highly meta- 
 morphic, resting upon deejjer ma- 
 terial of which we know nothing. 
 
 The visiljle rocks of this group 
 in North America for the most part 
 form a V-shajjed strip, extending 
 from Labrador southwest to the Great 
 Lakes, then northwest toward the Arctic Ocean. In Canada they are over 
 seven miles thick. Small patches are also found in the other continents. 
 
 Palaeozoic Era. — There was abundant life, both animal and 
 vegetable, during this era. Metamoi'phism is found in many of 
 
 the rocks ; but this feature is 
 far less frequently observed than 
 in those of the jirevious group. 
 
 In the Cambrian Age the 
 plants were all sea-weeds. The 
 animals, so far as known, were 
 in\'ertebrate {^without a hach- 
 hone) and lived exclusively in the 
 water. The most characteristic 
 creature of this age was the Tri'- 
 lobite {three lobes, into which its 
 body was divided), a crusta'cean 
 allied to the modern king-crab. 
 
 The Kilt-Rock, Loch Stafun, Skte ; its 
 Kilt due to Alternate Strata 
 
 Note, — The character and age of stra- 
 ta in such parts of the world as have been 
 explored are now generally understood. 
 Professor Jules Marcou has embodied all 
 the available information on this subject 
 in a geological map (reproduced on pp. 12, 
 13), showing the range of the chief groups 
 in both hemispheres. It will be observed 
 that the same order of strata is not to be 
 expected in every locality ; that owing to 
 causes already explained, Archiean, or the 
 lowest rocks, which if left undisturbed 
 would be buried beyond our reach, may be 
 surface features in one country ; Mesozoic, 
 in another ; etc. A complete order of strata 
 is never met with in any one place. 
 
 While occupied with the study of this 
 map in connection with Professor Newber- 
 ry's Geological Chart, the pupil will find it 
 both interesting and profitable to visit the 
 nearest geological museum for the purpose 
 of inspecting rocks, ores, and fossils. lie is 
 further recommended to familiarize himself 
 with the geological formations, minerals, 
 and organic remains, which may character- 
 ize the locality in which he lives ; and to 
 verify by liis own observation in field, quar- 
 ry, mine, and cutting, the knowledge im- 
 jiarted in this chapter and gleaned from the 
 books of reference. In cases where practical study of this nature is impossible, the teach- 
 er should, as far as circumstances permit, illustrate the subject with mineral specimens. 
 Valuable aids in thus acquiring the true method of this science will be found in Canon 
 Kingsley's " Town Geology," and Winchell's " Walks and Talks in the Geological 
 Field." Read also " My First Geological Excursion," in Geikie's " Geological Sketches." 
 
 fancied Kesembla.nce to the Higuland 
 OF Trap-Rock and Sandstone. 
 
LoiiKitude East ISO AVest from 
 
 iry""', -dr^r" ^^" ^"j l-°"gi""if 
 
 GEOLOGICAL MAP 
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 ^ A T r'TT A T?n^ ^y PI'OF. J. S. NKWBERRY, of Ciiluinbia College, N.Y. Illustrating the Dovel(>i)ment of Life on the EiUth fruni the Ardueiin Era to the Age of Man. 
 
 ^■ti-Li V7XAii±l/-L CHARACTERISTIC FOSSILS ARE SHOWN IN CONNECTION WITH THE SEVERAL SYSTEMS. Sw p 1"9. 
 
 MKSOZOIC 
 
 NEOZOIC 
 
Li 
 
 PALEOZOIC AND MESOZOIO ERAS. 
 
 Some of these trilobites were fully two feet in length. The pei-fec- 
 tion of the eye in many fossils is noticeable; the lenses, sometimes be- 
 tween three and four hundred in number, are arranged, as in the com.- 
 mon butterfly, so as to command an extended field, and suggest condi- 
 tions of water and atmosphere similar to those that now exist. From 
 the abundance of this crustacean, the Cambrian has been called " the 
 Age of Trilobites." 
 
 Silvirian Ages. — The two Sllu'rian Ages (so named from the 
 ancient Silu'res who inhabited that portion of Wales and England 
 where the rocks of these two systems abound) are alike in having 
 moUnsks (animals like the snail, with soft, fleshy bodies ; see p. lOt) 
 as their most abundant and characteristic fossils. Together they 
 form " the Age of Mollusks." Trilobites were still abundant, but 
 not the reigning type of animal life. 
 
 The Lower Silurian plants were all sea-weeds. The most pow- 
 erful animals were huge cuttle-fishes, one species of which was 
 provided with a straight conical shell, partially divided into cham- 
 bers. Some of these shells have been found a foot in diameter 
 and twenty feet in length. 
 
 The Upper Silurian fossils are almost entirely distinct from 
 those of the Lower Silurian system. Mollusks predominate, and 
 trilobites are abundant but diminishing. Many Corals are found, 
 but different from those of modern times. Quite munerous were 
 the Cri'noids (lUy-foi'ms), animals which were rooted to the sea- 
 bottom like plants, and presented a striking resemblance to lilies. 
 Their fossil remains are often called Stone-lilies. Vertebrates (ani- 
 mals with jointed skeletons, see p. 100) make their appearance in 
 the Upper Silurian Age, in the form of a few small fishes allied 
 to the stui'geon and shark. Land-plants, such as ferns and club- 
 mosses, are first found. 
 
 The life of the Devo'nian Age (named from Devons]ivce, 
 England) is marked by the great abundance of fishes ; but these are 
 of a low type, with imperfect bones, and having bodies often covered 
 
 with plate-like armor. It is called " the 
 Age of Fishes." Land-plants were now 
 numerous, and formed the first forests. 
 Devonian rocks are the principal source 
 of our mineral oil and gas. 
 
 The Carboniferous Age is so 
 called from the beds of coal which occur 
 in the rocks then deposited in Eiirope 
 and Eastern America. The "Coal-Meas- 
 ures" were beds of peat which accu- 
 mulated in marshes, and this by press- 
 ure and partial decay gradually became 
 bituminous coal. Where the Carbonif- 
 erous rocks have been metamorphosed, or otherwise subjected to 
 heat, the bituminous coal is converted into anthracite, or even into 
 graphite {plmiihago, or Mack-lead). 
 
 The trees during the Carboniferous Age were in many respects 
 very different from those that are now most abundant. Tree-fems 
 were of great size. Cane-like rushes grew to a height of forty 
 feet; club-mosses, which are now rarely more than a few inches 
 high, constituted an important part of the dense forests of those 
 times. 
 
 The animal life was similar to that of the j)receding age, with 
 the addition of some remarkable amphibians {adapted for living 
 on land or in water), creatures intermediate between fishes and 
 reptiles. A few true reptiles appeared during the last part of this 
 period, and the fishes were still low in type and somewhat reptilian 
 in their characteristics. Insects now for the first time occurred in 
 
 Coal-Fekn restored (aftek 
 Dawson). 
 
 Fish of the Coal-SIeasures (after Traquair). 
 
 considerable variety. (On coal-plants and animals of the coal-meas- 
 ures, considt Professor Thorpis " Coal, its History and Uses" 
 pp. 73 and 110.) 
 
 Mesozoic 
 Era. — During 
 this era reptiles 
 were the repre- 
 sentative ani- 
 mals, attaining 
 great size and 
 existing in large 
 numbers. It was 
 pre-eminently 
 " the Era of 
 Reptiles." Some 
 were adapted for 
 walking on the 
 
 land, some for swimming in the water, and others for fiying in the 
 air. These last were, therefore, bird-like in their characteristics. 
 Amphibians of great size formed the connecting links between 
 them and the fishes. 
 
 The life of the Triassic Age (represented by three series of 
 strata in the Old World) was marked by the prevalence of cone- 
 bearing and fern-like plants, and of amphibians and reptiles. Mul- 
 titudes of bird-like tracks, mostly three-toed, made by the latter, 
 are found in the Triassic sandstone of the Connecticut Valley and 
 New Jersey, varying from an inch to two feet in length. A few 
 small mammals {see p. lOS) of the lowest type existed toward the 
 close of the Triassic Age. 
 
 The Jvirassic System takes its name from the Jura Mount- 
 ains, in Switzerland. In North America it is, for the most part, 
 confined to the western portion of the continent, appearing in 
 Colorado, Wyoming, Idaho, and LTtah. 
 
 The Jurassic Age saw the culmination of the animal and vegetable 
 life of the Mesozoic Era. Eeptiles were the predommant type. Among 
 them was the largest animal known, the plant-eating Atlanto-sau'rus, 
 over one hundred feet in length, with a height of thirty feet. The Ich- 
 thy-o-sau'rus (fish-lizard) and the Ple'si-o-sau'rus {nearly a lizard) were 
 the rulers of the sea — the former, thirty or forty feet long, with short 
 neck, immense jaws, and eyes a foot in diameter ; the latter, with small 
 head and almost sw^n-like neck. Both were provided with paddles in- 
 stead of feet (see Geological Chart). Flying reptiles were also peculiar 
 to this period. The best known of them, the Pter-o-dac'tyl {winged 
 finger) had a distinctly reptilian head, jaws furnished with formidable 
 teeth, a breast-bone like that of a bird, a bony tail, and a pair of bat-like 
 wings attached to the elongated outer fingers of its hands. 
 
 The remains of the first bird are found in the Jurassic rocks ; the 
 seas swarmed with fishes. 
 
 The Cretaceous System takes its name from the Latin 
 word creta, meaning chalk, a chalky limestone constituting one of 
 its most important elements in England. This system covers more 
 of the sui-face of North America than any other, including the 
 clays and marls of New Jersey, as well as the sandstones, 
 shales, and limestones, which extend from the Mississippi Hiver 
 to the Wasatch Mountains in Utah, and from southern Mexico to 
 northern Canada. 
 
 The animals and plants were generally similar to those of the two 
 previous ages. A peculiar cretaceous bh'd was the Ich-thy-or-nis, with a 
 back-bone like that of a fish, a keel-like breast-bone, and no horny beak, 
 but a pair of long, slender jaws, well furnished with socketed teeth. Its 
 size was about that of a pigeon. 
 
NEOZOIC ERA. — ADVENT OF MAN. 
 
 15 
 
 IcHTHVORNis — Fish-Biril (aftek Macsii). 
 
 Neozoic Era. — At tlie clo.se of the Cretaceous age, the life of 
 the globe seems to liave been revolutionized ; the great annnouite 
 f;uni]y (allied to the nautilus), the most striking feature in Meso- 
 zoic iniilluscan life, and ^ill the cliai'acteristic reptiles of the Rep- 
 tilian ages, di.sappeared, 
 while mauitnals iinilti- 
 plii'd and increased in 
 size until they spread 
 over and ruled tlie earth. 
 Birds also in the later 
 Cretaceous epochs grad- 
 ually superseded the fly- 
 ing reptiles, and in the 
 Tertiary wholly replaced 
 them. The natural world 
 then assumed its present 
 aspects, and subsequent 
 changes have been m de- 
 gree, not in kind. 
 
 In North America 
 the Tertiary Ajye 
 
 seems to have been the 
 most interesting part of 
 its geological history. 
 The continent had then 
 nearly its present form 
 
 and dimensions; the sea covering only a narrow margin along the 
 iVtlantic and Pacific coasts, and reaching up the valley of the Mis- 
 sissippi as far as the mouth of the Ohio, The western ])ortion of 
 the continent was occupied by a series of great lakes, which in suc- 
 cession were filled or drained, changing their places or outlines at 
 different epochs. The climate was mild to the Arctic Sea; the 
 entire land-surface was covered with a luxuriant vegetation, and 
 inhabited by a more abundant and varied fauna than now exists in 
 any portion of the earth. The remains of this fauna and flora are 
 found buried in the .sediments by which the old lakes were tilled. 
 
 Already many hundred species of land-animals and land-plants, 
 with fresh water fishes and mollusks, have been obtained from these 
 great cemeteries, and many more remain to reward future collectors. 
 
 From strata of the Tertiary Age in Greenland and Alaska, 
 plant-remains have been obtained which show that om- cypress, 
 magnolias, tulip-tree, and sweet-gum, grew along the shores of the 
 Arctic Ocean, and with these many colossal trees which have 
 since disappeared. The giant trees of California, as also the finest 
 elements in the Eastern forests, are relics of the luxuriant vegeta- 
 tion of the Tertiary Age. 
 
 The Tertiary is called the ''Age of Mammals." All the mammalian 
 types were represented, but the differences of species were not so marked 
 a.s at present. The hoi-se appears during this age, first as a little creat- 
 ure, the size of a fox, with three hoofed toes on each hind-foot and four 
 hoofed toes on each fore-foot ; later it attains the size of a sheep, and is 
 provided with three toes on each foot ; and still later, it develops into a 
 single-hoofed animal, about the size of an ass, each foot provided with a 
 pair of side-toes, not long enough to reach the groxind. 
 
 Quaternary Age. — Age of Man. — After the Tertiary 
 Age had continued long enough for the deposition of many thou- 
 sand feet of strata, a great change took place in the climate of the 
 northern hemisphere. That of the Arctic regions, which had 
 been warm temperate, changed to what it is at present (in conse- 
 quence, it is supposed, of a variation in the eccentricity of the 
 
 earth's orliit). This change progressed mitil the climate now 
 characteristic of Greenland and Alaska was brought down as far 
 as New York, and all the more northern portions of the American 
 Continent were bui'ied under sheets of perpetual snow and ice. 
 Animal and vegetable life was either totally destroyed or driven 
 with many losses into southern lands. (On the work of the Glacial 
 Time, and the eft'ect of glaciation on the life of the earth, cansnlt 
 VrqfeHsors Shaler and Davis's " Glaciers,^'' pp. ^9 and 117.) 
 
 This is called the Ice Period. The proof that glacicrK covered all the 
 liighlaiid of the northern lialf of this couliuent is found in th(> iilaiicd 
 and worn condition of the surface-rocks, and the southward spread 
 of great sheets of sand, gravel, and' bowlders, from their places of origin 
 — phenomena which only moving ice could produce. These glaciers 
 after a time receded with tlie return of more moderate climatic conditions. 
 
 Similar traces of the Ice Period are found in Europe, Asia, AustraUa, 
 New Zealand, and South Amei'ica ; but it is not pi'oliable that the cold 
 periods occurred at the same time in the northern and southern hemi- 
 spheres. (See Croll's " Climate and Time in tlieir Geological Relations.'") 
 
 Life diu'ing the Ice Period seems to have been much like that of the 
 present day ; but many animals similar to those that now dwell in torrid 
 regions were then adapted to a cold climate. The Mammoth was an ele- 
 phant, about twice the size of that now found in Asia, but distinguished 
 from the latter by its dense uuder-coat of wool and long, coarse outer 
 hair. Immense numbei-s of more or less entire mammoth-carcasses have 
 been found in the frozen soil of northern Siberia ; for centuries the fossil 
 ivory fiu'uished by their huge curved tusks has been an important article 
 of Eastern commerce. The woolly rliinoceros, the mastodon, the great 
 Irish elk, the cave-bear, the saber-toothed tiger — these and many other 
 species probably preceded man, and have become extinct since the begin- 
 ning of the human epoch. In New Zealand are found the remains of 
 the gigantic Mo'as, wingless birds about twelve feet high. 
 
 The Advent of Man. — Up to the present time no remains 
 of man have been found in deposits older than the Ice Period. In 
 
 Europe, where the subject has lieen most thoroughly studied, it is 
 thought that the first traces of man date from the time when the 
 great glaciers began to disappear. Along with the hairy elephant 
 and the woolly rhinoceros, the muslv-ox and the reindeer, he fol- 
 lowed the ice-fields and glaciers in their retreat to the far north. 
 The prehistoric man of central Europe is believed to be now rep- 
 resented by the Finns and Lapjis. He dwelt in caves, used the 
 rudest stone implements, and contended with the other mammalia 
 for the mastery of the earth. Of primitive man in Asia and 
 Africa, nothing is definitely kno^vn. (On the antiquity of man, 
 consult Daivl'bis^s '"'■ Earbj Man in Britain''^; Wihoiis '■^Pre- 
 historic ManP) 
 
 Questions. — Of what is the earth's crust composed ? How are rocks classi- 
 fied ? To what do the several varieties owe their origin ? Explain strati- 
 fleation. Prepare a geological section illustrating varieties of .stratification. 
 Show, by a simple diagram, the nature of fissures, faults, and veins. 
 Describe the appearance of rocks in a quarry or cutting, and tell what 
 you understand by soil. By what agencies have changes in the earth's 
 surface features been produced ? Explain erosion ; contraction by cooling 
 of the earth's crust. How may we infer the future of our planet ? 
 
 What are fossils ? Explain their value to the geologist. What minerals are 
 derived from fossil vegetation ? Into what eras does geology divide the 
 history of the globe ? Name the systems of strata corresponding to each 
 Give an account of the animals and plants which characterized the several 
 geological ages, and enumerate the changes that marked the beginning 
 of the Neozoic Era. What climatic change, how explained, occurred at 
 the close of the Tertiary Age ? Give an account of life during and after 
 the Ice Period. What is known of the advent of man ? Explain the 
 peculiarities of a geological map. Let the pu]iils prepare (in colors) an 
 outline map, illustrating the geological structure of North .\nicrica; also 
 a geological map of their own state, if the necessary data can be obtained. 
 (See specimens in Appletons' Geography of Virginia, of Pennsylvania, and 
 of South Carolina.) 
 
PHYSIOGRAPHY. 
 
 The Relief of the Earth. — The surface of our globe is 
 crumpled or corrugated. Great masses of the crust have been raised, 
 and extensive areas depressed. The largest elevated areas, which 
 rise above the ocean, are knowu as continents ; the great depressed 
 areas, as oceanic valleys, being tilled, up to a certain level, by the 
 sea. These primary elevations and depressions are diversified by 
 numerous secondary ones, producing the great plateaus and val- 
 leys, which give their general character to the continents; while 
 tliese, in tum, are traversed by numerous smaller lines and grou^DS 
 of elevation, forming mountain- and hill-ranges, when they are 
 abrupt and steep, and smaller plateaus, when the slopes ai"e gradual. 
 
 All this Relief, as the alternation of elevation and 
 depression of the earth's siu'face is called, is, as has been 
 shown, the result of the opposing action of two agencies, 
 that of strains or stresses in the solid crust of the earth, 
 which produces elevation ; and that of erosion, which 
 cuts down and washes away. The science that treats of 
 the relief of the earth, as well as of the system in the 
 physical changes on the earth's surface, is known as Physi- 
 ocj'raphy. 
 
 Movements of the Earth's Crust. — The 
 
 crust of the eai'th is not in a state of ecjuilibrium. 
 It is constantly subject to strains, and some portion of 
 it is always in motion, either rising or sinking. Fos- 
 sils found in the strata which compose certain mount- 
 ain-ranges prove them once to have been sea-bottoms. 
 Regions of elevation and depression are usually long 
 in proportion to their breadth, as is seen in the form 
 of the continents and in mountain-ranges. 
 
 Elevation takes place in one of two ways : Fu-st, beds of rock may 
 be bent upward in the form of an arch, without breaking. The rise may 
 bo very slight in proportion to the breadth of the uplift, as is the case 
 with the continents and great plateaus ; or it may be great, as is to be 
 seen in many mountain-ranges. 
 
 The second form of elevation is that in which the beds of rock are 
 broken, and those on one or both sides of the break are bent upward.. 
 This form is seen iu many mountain-ranges and smaller plateaus. The 
 slope is generally much steeper on the broken side. 
 
 It is in this way that the land rises ; but while rising, and in- 
 deed always, it is subjected to the attacks of an opposing agency, 
 from which it will be freed only when it has been reduced to the 
 level of the sea. (On the movements of the land, see Huxley's 
 '■'■ Phxjsiography^'' p. Wo.) 
 
 Erosion. — No sooner does the land bearin to rise, than the 
 agencies of erosion, always at work, are brought into increased 
 activity. Rain falls more abundantly and streams are swollen. 
 The slope of the stream-beds also becomes greater; rivers flow 
 more swiftly, and are capable not only of carrying ofl: large 
 amounts of sand and gravel, but cut away their banks and beds 
 with greater speed. The temperature falls, and frosts disintegrate 
 tiie rocks more rapidly into soil. The winds blow with increased 
 force, and, carrying sharp sand, play a very efiicient part in planing 
 down the countiy. 
 
 By means of these agencies, which are constantly at work lev- 
 eling the land, a great part of the eflfoi-ts of the forces of elevation 
 liave been brought to naught. Enormous masses of rock have been 
 ground to powder, and carried down into the valleys or deposited 
 upon the bed of the sea. From vast areas of land, strata of rock, thou- 
 sands of feet thick, have been removed. Wliole continents with their 
 
 mountain-ranges and plateaus have thus been worn away, and the dry 
 land upon which we live to-day has been built of their debris. 
 
 THE LAKD. 
 
 The Whole Area of the earth's surface comprises about 
 197,000,000 square miles. Of this area, a little more than one- 
 fourth (about 52,000,000) is land, while nearly tliree-fourths is 
 covered by the sea. The deepest parts of the ocean are about 
 5|- miles below the surface, while the highest mountain-peaks are 
 
 Land and Water Hemispheres. 
 
 almost as far above it. The distance from the depths of the sea 
 to the summits of the highest mountains is therefore a little less 
 than eleven miles, and this represents the total relief of the earth. 
 Let us compare this with the earth's magnitude. The length 
 of the earth's radius is not quite 4,000 miles ; its reKef is then 
 but ^ji^ of its radius. If the earth were represented by a ball 
 
 si.x feet in diameter, 
 the tops of its high- 
 est mountains should 
 be represented as but 
 one-tenth of an inch 
 above the deepest ocean 
 bed. ■ 
 
 If the surface of the whole 
 earth be represented by that 
 •of the largest circle, then the 
 circle marked A will on the 
 same scale represent the area 
 of Europe and Asia; B, Af- 
 rica ; C, North America ; D, 
 South America; E, Australia; 
 F, the sum of all the islands 
 liDown. The rest of the space 
 within the large circle rep- 
 resents the sum of all the 
 oceans. 
 
 While the land covers fully a fourth of the earth's surface, and its 
 greatest elevations neai-ly equal the lowest depths of the sea, its volurne 
 is very much less proportionally than that of the ocean. The great ele- 
 vations of the land are mountain-peaks, while the great depressions of 
 the sea consist of broad valleys. The average height of the land is esti- 
 mated to be about 1,,500 feet, p.nd the average depth of the sea about 
 12,000 feet, or eight times as much as the height of the land. The vol- 
 
 CoMPARATivE Areas of Land and Water. 
 
NATURAL DIVISIONS OF LAND. 
 
 ume of water composing the sea is therefore about twenty-four times as 
 great as that of the land lying above sea-level. If the earth's surface 
 were flat, the sea would cover it uniformly to a dej)th of about 8,.')()0 feet, 
 or more tluui a mile and a half. 
 
 The Oceanic Valleys. — The greatest valleys of the earth 
 are occupied by the sea. The contiueuts are vast plateaus separat- 
 ing tlie oceanic valleys. These continental plateaus are not always 
 wholly above the sea ; their outskirts are beneath the waves. There 
 are other plateaus and raoun tain-peaks of less height, which, rising 
 from the bed of the ocean and barely reaching the sea-surface, 
 form islands ; while yet others, still less elevated, are entirely sub- 
 merged. 
 
 The Pacific Ocean occupies ' ..■*' 
 
 the largest and deepest valley 
 on the globe. From its depths 
 many moimtain-peaks rise to 
 the surface as islands ; and it is 
 separated from the Indian Ocean 
 by a great plateau, extending 
 southeastward from Asia, part 
 of which is below and part 
 above the surface of the wa- 
 ter. Java, Sumatra, Borneo, 
 Australia, and New Zealand, 
 ai'e included in this plateau. 
 
 In some places the bottom 
 of the sea slopes off very gradu- 
 ally from the land for great 
 distances seaward, as about the 
 British Islands and Newfound- 
 land; while in other places, the 
 water deepens abruptly from the 
 coast-line, as m the neighbor- 
 hood of Japan and the Kurile 
 (Koo'ril) Islands. (See map, 
 pp. 20 and -21.) 
 
 Distribution of tlie 
 Laud. — The land is very un- 
 equally distributed over the 
 surface of the earth. Not less 
 
 than three-fourths of it lies north of the Equator, while 
 the southern hemisphere is mainly covered with water. 
 
 It is possil)le to divide the earth, by a great cii'cle 
 oblique to the Equator, in such a manner as to throw nearly 
 ail the land into one hemisphere. 
 
 Contiueuts and Islands. — Those portions of the 
 land which rise above the sea are known as continents and 
 islands. A continent is simply a large island. There are 
 four bodies of land which are ranked as continents : First, 
 the Western or American Continent, comprising North 
 and South America; second, the Eastern Continent, com- 
 ]irising Eurasia (Europe and Asia) and Africa ; third, Aus- 
 tralia; and, fourth, the Antarctic Continent. Islands may l)e 
 classed as continental and oceanic. The former lie near conti- 
 nents and properly form parts of them. They generally rise from 
 comparatively shallow water, so that a slight depression in the 
 ocean-level would lay bare a connecting isthmus. They are fre- 
 quently long in proportion to their width, and parallel to the shore. 
 In many instances they are the summits of submerged mountains, 
 as in the case of the Aleutian Islands on the northwest coast of 
 North America, and Tierra del Fuego at the southern extremity 
 of South America. 
 
 Oceanic islands are those located far from large bodies of land. 
 They are either volcanic in their origin, or the work of coral pol'- 
 yps {see p. 30). Volcanic islands are generally small in extent and 
 mountainous. 
 
 The great bodies of land upon the globe show certain general pecul- 
 iarities and resemblances. With hardly an exception they are broadest 
 in the north. This peculiarity is strongly marked in North and South 
 America and Africa, and may easily be traced in Eurasia. They tajier 
 to points southward, as is seen in the two parts of the American Conti- 
 nent and in Africa. This is true not only of most of the continents, but 
 also generally of the great peninsulas jutting from them, such as Florida, 
 in North America; Scandinavia, Spain, and Italy, in Europe; and Hm- 
 
 dostan, Corea, and Kamchatka, 
 iu Asia. Eurasia is compai-ablc 
 to a huge hand "stretching with 
 open frngei-s toward the south." 
 
 
 Plains and Mount- 
 aius. — The infinite variety 
 in the relief of the earth's 
 
 AMKIUCAS PllAll'.lli, 
 
 surface may be classified into 
 two general groups of feat- 
 ures — Plains and Mountains. 
 Mountains are high, abrupt 
 elevations of land. All land 
 that is not mountainous may 
 he regarded as constituting 
 plains, which occupy by far 
 the greater part of the exposed 
 surface of the earth. 
 
 A Plain may be level, 
 or undulating, rolling, or even 
 broken and hilly. Its surface 
 may be horizontal, or inclined 
 at low angles. Its elevation 
 above the sea may be small 
 or o-reat. When high above 
 sea-level, it is generally known 
 as a Plateau or Table-Land. 
 Its limits may be sharply de- 
 fined by a line of ascending 
 or descending cliils, in which 
 ease it is akso called a Plateau, 
 or, if of small extent, a Mesa 
 {men' a). It may lie between 
 two mountain-ranges or pla- 
 teaus, and be the result either 
 of erosion or of the fracture 
 of upheaved rock-masses ; in 
 this case it is called a Valley. 
 It may be low and wet, when 
 it is known as a Swamp, Bog, 
 or Marsh; and, if it be so near the North or South Pole as to be 
 constantly frozen, at least in part, it becomes the Tundra of the 
 Arctic regions. It may lie under an arid climate, when it is more 
 or less completely a Desert. It may be covered \vith forests, as in 
 the Silvas of the Amtizon, of South America; or it may be mainly 
 grass-grown, with occasional belts of trees, like the Prairies (in 
 French, meadoios) of North America, the Llanos {hjah'noce; in 
 Spanish, /«r<'/.y) and Pampas (in Peruvian, jijfowi.*;) of South Amer- 
 ica, and the Steppes of Siberia. Barren, sandy levels, chiefly used 
 for pasturing sheep, are known in England as Downs. Elevated 
 
18 
 
 VARIETIES OF PLAINS. 
 
 lands, covered with a growth of small trees, but not timber, are 
 called Barrens ; they are not necessarily sterile. 
 
 It will thus be seen that the word i^lo-in is a very general term, not 
 admitting of short or exact definition. Some of the varieties of plains 
 defined above will now be described moi-e in detail. 
 
 Plateaus. — In the southwestern part of the United States, 
 there is a region of typical plateaus or table-lands. It is the area 
 
 drained by the Colorado River and its tributaries. The surface of 
 the plateaus is nearly flat ; there is no rolling, undulating, or hilly 
 country. Changes of level take place by gentle slopes ; or by 
 abrupt, precipitous cliffs, often of great height. The whole country 
 is angular. There are no valleys ; every stream is in a canon {kan- 
 yun), or gorge between steep banks, and flows hundreds, or it may 
 be thousands, of feet below the level of the country. As this is an 
 arid region, there are many canons which are dry during most of 
 the year. 
 
 Some of these carions are of enormous depth, that of the Coloi'ado 
 River being, at the deepest place, nearly 7,000 feet below the surface of 
 the plateau. The walls form a succession of steps, a veritable giants' 
 staircase, with I'ises of 1,000 to 2,000 feet each. 
 
 In some regions, canons are so niunerous that they have left but a 
 mere skeleton of the original plateau, which has the form of nai-row, 
 level ridges, separating the countless gorges of the streams. lu other 
 places the rains, streams, and winds, have worn away whole beds of rock 
 from gi-eat areas, leaving only here and there a fragment of harder 
 rock, which has successfully withstood the attacks of the elements. 
 These fragments, which are usually flat-topped, with precipitous sides, 
 are known as Buttes (butz). (On the carLons of the Coloi'ado and Major 
 Powell's expedition, see " Our Native iawd," p. .4.) 
 
 Swamps. — Swamps occur mainly in regions of heavy rainfall. 
 They commonly occupy level country, where the slope is not great 
 enough to carry off the water. In many places along the sea-shore 
 are found areas which are so slightly elevated as to be flooded at 
 high tide. These are known as salt-marshes. Swamps are usually 
 covered with rank vegetation, and frequently with forests. The 
 decay of this vegetation produces a rich soil, which makes tlie land 
 valuable when reclaimed. 
 
 Tundras. — Along the shores of the Arctic Ocean {see " Map 
 of JYorth Polar Regions,'''' p. SIf), in both Asia and America, ex- 
 tending for hundreds of miles to the south, are vast level areas of 
 what is called Tundra. In this cold region the soil is frozen con- 
 stantly to a great depth. In the short, hot summer, the surface 
 of the ground thaws, while below it remains solid. The surface 
 quickly becomes covered with a luxuriant growth of heath and 
 Arctic mosses, the latter afliording food to the reindeer. This dense 
 vegetation, together with the absence of slope, prevents the water 
 from flowing off, and so the surface of the ground, covered with 
 these mosses, is, like a wet sponge, constantly saturated with water. 
 Travel in such a region in summer is almost impossible ; but in 
 winter, when all is frozen and covered with snow, the sledge, 
 drawn by dogs or reindeer, affords a rapid aiid easy mode of loco- 
 motion. (For a description of a Siberian moss-steppe, see Ken- 
 narus " Tent-Life in Siberia" p. 130.) 
 
 Deserts owe their existence to the lack of rain. A typical 
 desert is without vegetation or soil, its surface consisting of bare 
 rock, or covered with shifting sands. A region, however, may 
 still be a desert, though in less degree, if its surface is covered 
 with soil, and even with sparse vegetation, such as the artemi- 
 sias and cacti, of little value to man. Fertile spots in deserts are 
 called O'ases. 
 
 Steppes, Llanos, Pampas, and Great Plains. — The 
 
 steppes of Siberia, the llanos and pampas of South America, and 
 the great plains of Noi'th America, resemble one another in general 
 appearance. They differ mainly in temperature. The climate, as 
 regards moisture, is semi-arid. There is not sufhcient rain for the 
 needs of trees, but generally enough for grasses. Such regions, 
 therefore, occupy a position midway between deserts and forest- 
 covered plains. Their surface is generally monotonous and undu- 
 lating. The valleys of the few streams are but slight depressions, 
 while the divides between the streams are not well deflued. There 
 ai'e few landmarks, and the traveler over these great wastes is easily 
 lost, if he leaves the beaten paths. (On Patagonian pampas, see 
 Muster's ^'- At Home with the Patagonians" p. 15.) 
 
 The Praii'ies of North America form a connecting link be- 
 tween the Great Plains and the forest-covered levels in the north- 
 ern part of the Mississippi Valley. They everywhere occur along 
 the line of junction of these two kinds of plains, but generally in 
 narrow belts. They are better watered than the Great Plains, and 
 hence are mainly covered with luxuriant grasses, interspersed with 
 groups of trees, the latter becoming larger and more freqiient as 
 the forest-region is approached. Wild flowers of gay hue are in 
 their season an attractive feature. The surface is usually level or 
 gently rolling. 
 
 Where the seasons are distinguished as wet and dry, such grassy 
 plains, which afford pasturage during the rainy season only, are called 
 Savannas (in Spanish, linen sheets, from the appearance of the plains 
 when covered with snow). Treeless regions of less extent are known in 
 Europe as Heaths. 
 
 Forest-covered Plains. — Where the rainfall is sufficient 
 for the needs of trees and the climate not too cold, the plains be- 
 come covered with forests. The most magnificent forest-coverod 
 plain in the world is the region drained by the Amazon River. 
 Here vegetable life, under the stimulus of a tropical sun and an 
 enormous rainfall, attains extraordinary luxuriance. The soil pro- 
 duces a heavy growth of immense trees, among which are crowded 
 herbaceous plants and climbing vines, making a mass of vegetation 
 so dense that it can not be penetrated. The only avenues of travel 
 through these Silvas of the Amazon, which cover a million square 
 miles, are by the great river itseK and its himdreds of branches. 
 
 Mountains are abrupt elevations of land. Hills have less 
 height. Mountains occur most commonly in long ranges, having 
 a definite direction or trend. They also appear in groups with 
 little or no apparent system, and in isolated peaks ; in the latter 
 case they are usually of volcanic origin. Mountain-ranges are gen- 
 erally grouped in systems, the several chains having a common 
 direction, and being separated by narrow valleys. Thus the Rocky 
 Mountain system of North America, which crowns the great west- 
 em plateau, consists of many ranges, all trending nearly north and 
 south. The geographical axis of a continent is the main ridge, 
 not necessarily continuous or the highest water-parting, from 
 which the land slopes and the water flows in opposite directions. 
 
 Mountain-ranges differ greatly in length, breadth, height, and angle 
 of slope. Some run for hundi'eds, and even thousands, of miles without 
 a break, as the Andes, which traverse the South American Contmcnt 
 from north to soiith in an unbroken line. Some single ranges are fifty 
 miles in breadth, rising upon either side in long slopes, cut into spurs or 
 secondary ranges by torrents ; while others, having steep, simple slopes 
 or cliif s on the sides, are not more than two or three miles in breadth 
 between the valleys at their bases. A mountain range or chain is some- 
 times known as a Cordillera (Ln Spanish, little rope) ; also as a Sierra 
 (saw) when marked by a succession of pointed summits. 
 
MOUNTAINS, THEIR HEIGHT AND VEGETATION . —CAVERNS. 
 
 19 
 
 The Heifjlit of Moimtains. — Wlien we speak of the 
 Iiei<2;lit of ;i iiiomitaiii nr of a range, it is generally its height above 
 mean sea-level that is intended, as that is the most convenient level 
 to which it can l)e referred. In very few eases, howevei-, does this 
 represent the height of the mountain above its base, which is gen- 
 erally very much less. 
 
 Tlius, we spouk of Mount Lincohi, in Colorado, as being 14,297 feet 
 high — that is, above sea-level. This mountain stands, however, upon a 
 plateau 10,000 feet above the level of the sea, so that its height above the 
 country at its base is but little more than 1,000 feet. A mountain hav- 
 ing an elevation of more tlian 10,000 or 12,000 feet above its base is rarely 
 found ujwn tlio eartli; while, commonly, the high mountains do not rise 
 more than half that height. The most abrupt elevations are usually 
 found in the case of volcanic peaks. 
 
 Erosion of Mountains. — Wherever erosion, from one eanse 
 or another, has produced but little effect, we find the mountain- 
 ranges ver\' nearly in the condition in which they were at the time 
 of upheaval. Such ranges 
 have smooth slopes and 
 level tops, whether they 
 be broad and plateau-like, 
 or narrow and sharp. 
 
 But where rains, riv- 
 ers, winds, and frosts, have 
 had unrestricted play, the 
 result is very different. 
 The sides of the range 
 are deeply scored by the 
 beds of streams, ])roducing 
 gorges or canons if they 
 are narrow, and valleys if 
 they are broad. Between 
 them stand fragments of 
 the original mountain, 
 which are known as spurs. 
 These spurs themselves 
 may in turn be carved into 
 a succession of secondary 
 spurs and gorges. (On 
 mountains and their origin, 
 consult Agassi z's " Geohyj- 
 ical Sl'etches,^' p. 94.) 
 
 Mountain - streams have 
 their origin far up in tlie 
 
 heart of the range, and by them the crest-line itself is cut into a suc- 
 cession of high points and depressions. The former are known as Peaks, 
 or locally as Domes, Balds, etc. The depressions, if pi-acticable for travel, 
 are called Passes or Gaps. 
 
 A mountain-range is sometimes divided into two parts by a 
 depression through which a stream may flow from the valley on 
 one side to that on the other. Such a depression is known as a 
 Water-gap. The notch in the Blue Ridge, through which the 
 Potomac flows, is an example of a water-gap. 
 
 The origin of water-gaps is interesting. In many cases, the river 
 occupied its present com-se before the mountain wa.s there. It had the 
 right of way, and as the mountain slowly rose, the river, aided by the 
 shai'p sand and other eroded material which it was bearing to the sea, 
 began to cvit its way tlirough the barrier which was forming across its 
 path. In very few cases have rivers failed to maintain their courses 
 throvigh sucli obstacles. Mountains may rise and be eroded away ; 
 rivers not only flow on, but retain their ancient beds. 
 
 Campbell's Hall, Lcray Cavern. 
 
 The Ve}?etation npon Monntains. — Mountains are gen- 
 erally covered, up to a certain height, with forests, unless these 
 have been removed l)y the hand of man. Forests recpiire a com- 
 paratively humid climate and heavy rainfall. The warm and moist 
 air-currents wliich pass over the low countiy are, on reaching the 
 mountains, forced upward into colder regions of the atmosphere. 
 There they become chilled, and unable to hold as much moisture 
 as before. Thus they are compelled to precipitate a portion upon 
 the mountains, which are thereby well watered and clothed in for- 
 ests, though the plains all around may be arid and ban-en. In 
 some of the hottest, most arid, regions, however, even the mount- 
 ains fail to induce clouds to form and rain to descend ; such 
 mountains are not clothed with forests. 
 
 Tlie Timber-Line. — At a certain height upon the mount- 
 ains, where the average temperature for the year is below the 
 freezing-point, the climate becomes too severe for trees to grow. 
 
 This is called the timber- 
 line. Above it there is 
 little vegetation, except 
 certain hardy grasses. 
 
 The timber-line varies 
 greatly in height in differ- 
 ent parts of the globe. It 
 is highest near the Equator, 
 where the temperature is 
 greatest, and descends as 
 the latitude increases. It is 
 highest also where the coim- 
 try surrounding the mount- 
 ains is high, and descends 
 as the base of the mountains 
 approaches sea-level. Most 
 of the smaller mountains do 
 not reacli the timber - line, 
 and are or may be covered 
 witli forests to their sum- 
 mits. 
 
 Tlie Snow-Line. — 
 
 At a still higher level 
 upon the mountains, snow 
 is always found, even in 
 midsummer. The lower 
 limit of perpetual snow is 
 known as the snow-line. 
 In the United States, snow 
 lies throughout the year, in large bodies, only on the highest of the 
 extinct volcanoes of the Cascade Range in Oregon and Washing- 
 ton, and upon the mountains of Alaska. 
 
 Caves and Grottoes. — In many regions, especially where 
 limestones ai"e abundant, caves are found, usually opening on the 
 slopes of mountains and hills, or the abrupt sides of valleys and 
 ravines. Limestone is very soluble in water which contains car- 
 l)onic acid, and such water, percolating through the I'ocks, dissolves 
 them and carries them away. In time, great quantities of rock are 
 removed, leaving underground chambers and passages miles in ex- 
 tent. Thus have been excavated the Mammoth Cave of Kentucky, 
 extending nine miles underground in a wonderful succession of 
 avenues, abysses, domes, lakes, and rivers ; the Luray Cavern of 
 A'irginia, with its " diamond chambers," rich in crystal beauty ; 
 and many others less notable in these states and in Tennessee. 
 {Consult Dr. Hovey's ^^ Celebrated American Caverns.") 
 
East ISO 
 
 ■\\'ost 100 Lonffitiule 140 from 120 GrccnM-iuh JOG 
 
 10 Lonn-itilde 30 "^fest 
 
 East 1?0 "tt'est 100 Longitude 140 
 
 130 Greenwich. 100 
 
 10 Longitude 30 
 
 West 
 
 PHYSIOGRAPHY 
 
 EXPLANATION OF COLORS. 
 
 HEIGHT OF LAND. 
 
 From Sea Level to 600 feet, 
 it X mile - 
 I, S miles ... 
 .. 5 miles ... 
 
 DEPTH OF WATER. 
 
 From Sea Lev 
 
 czn 
 
 A ^niles t 1 
 
 'el to over It Guiles- I I 
 
 1 From Sea Level to 600 feet I I 
 
 J II II II II 3 viile I I 
 
 11 11 II II 2 miles I I 
 
 .1 Smiles I I 
 
 tt It miles.— I I 
 
 From Sea Level to over i miies. I I 
 
 Land Surface below Sea Level I 
 
 Questions on the Physiographic Map.— Elevations and depths, as 
 shown on this map, are measured in geographical miles, each of which is a trifle more 
 than six thousand feet. 
 
 If we give the general name, lowland, to regions whose elevation is less than six 
 hundred feet, and Idghland to those exceeding six hundred feet, which contains the 
 larger proportion of lowland, North America or Europe ? If ocean-depths of less than 
 six hundred feet be called shallows, where are the most extensive shallows found ? 
 What ocean contains the most extensive deeps ? Name the largest of these. Trace 
 out the most extensive plateau-region exceeding two miles in height. What similar 
 region in the opposite hemisphere comes next to this in area ? In what part of North 
 America is the elevation between one and two miles ? Is there any such region between 
 
frum cn Ciiinwi.li RO 
 
 R 
 
 r /^v -•';■;? •^K 
 
 
 
 ti<I>oahdo 
 
 ■^•^ 
 
 
 ^ 
 
 JV 
 
 WRANCELL I. 
 
 «:r I ^' <"' 
 
 •.* 
 
 &^''"~ 
 
 -<r/( 
 
 P^- 
 
 r^'^; 
 
 ridonU/i^ 
 
 ^^t^j 
 
 manjaro ^ 
 
 EQUA'X>R ■ 
 
 nop' C 
 
 -,5i// I InWSCARENEis 
 
 Bombay*^ o"\ ^^/p'' £ ^ }' »\ t 
 
 "OcEYU 
 
 N l> I a"- 
 
 TfK)pi( or CAPRrconw 
 
 c ' ^ 
 
 Madras / ^ 
 
 ishimghar;;' ^ f' 
 
 ^^ ^ 
 
 
 
 „ KL^<|| 15 
 
 Hares O- 
 
 '^S^ 
 
 
 
 ^ 
 
 4^ 
 
 C.L'"- 
 
 V" ,*' 
 
 ..'^^ ^' 
 
 
 .• f'-SOl./-;. 
 
 * SLES 
 
 
 *. ■S-E'-l 
 
 •Sydney 
 
 u 
 
 MACOUARIE IS.* 
 
 ■S- A- A '■ // 
 
 r a-'. Deep 
 
 XeHis* 
 ■ San* 
 
 . > 
 
 —TftOP(C-Of CANCER 
 
 Cj islands 
 
 .^. . 
 
 ±:.:. 
 
 GILBERT 15. 
 
 ^r^ 
 
 : SAMOA IS 
 
 FIJI £>^*i 
 ISLES 
 
 ...ME.W : iS- 
 
 CALEDONIA ! 
 
 •NORFOLK I. • ^\ 
 
 : ■■ KERMADEC 
 IS. 
 
 w iB^'" 
 
 -g-g^ 
 
 ^^*' .*<^ . ^CHATHAM I. 
 
 AUCJtUNO I.* ANTlfOOES I. 
 
 CAMPBELL I. , 
 
 20 
 
 from 
 
 40 
 
 Green wii.-h 
 
 60 
 
 k and the Atlantic ? Where is the Heig;ht of Land ? Is its elevation less 
 iir more ? Which of the great divisions contains the highest highland ? 
 t lowland ? In what parts of America is the elevation between two and 
 i V Where are similar regions found, if at all, in Europe ? In Africa ? In 
 Are there any regions whose elevation is between three and four miles in 
 In Europe ? In Asia? In Africa? Find whether any areas of land are below 
 1 Africa; in Europe; in North America. Give the position of each of the 
 asiiis. Where is Challenger Deep? Dolphin Rise? NorrisDeep? Chal- 
 The greatest measured depth ? What is this depth in miles? Where is 
 -y'f Belknap Deep? Connecting Rise? International Deep? Calculate 
 .■pth in miles. Is the depth for the most part greater than six hundred feet, 
 
 or less, in tlie North Sea ? Mediterranean Sea ? Bering Sea ? China Sea ? Baltic 
 Sea? Caspian Sea? Arafura Sea? Gulf of Mexico? Gulf of Bothnia? Yellow 
 Sea? Persian Gulf? Hudson Bay? Black Sea? Aral Sea? Caribbean Sea? 
 From what ocean-depths, and where, do islands rise between two and three miles above 
 sea-level ? If the sea-level were depressed one-tenth of a mile, would it be possible (o 
 travel from New York to London by land ? By what route ? Could the trip be made 
 wholly by water? If the sea-level were elevated one-tenth of a mile, where would be 
 the head of the Gulf of Mexico? Of the Gulf of St. Lawrence? What long penin- 
 sula would extend northward from Eurasia ? What American empire would become a 
 large island? What cities of North America would be submerged? How near would 
 the ocean come to the highest mountain in the world? 
 
22 
 
 THE AMERICAN CONTINENT. 
 
 Some caves contain deposits of carbonate of lime hanging like icicles 
 from the roof, or rising in the form of columns from the floor. Water 
 charged with lime percolates through the roof of a cfive, whence it falls 
 drop by drop to the floor. Here it evaporates, and leaves the insol- 
 uble limestone behind, slowly building up a fantastic column. This is 
 known as a stalagmite. In other cases it evaporates before falling, and 
 so leaves the deposit hanging from the roof in the shape of a stony tassel 
 or long incrustation called a stalactite. In some instances, the stalag- 
 mites and stalactites are extended until they meet. Stalagmites have 
 been observed to grow at the rate of a httle more than a quarter of an 
 inch per annum. 
 
 A famous stalactite cavern is the Grotto of Adelsberg, in Carnio'la, 
 Austria. Translucent sheets of spar hanging in the graceful folds of 
 drapery, tinted formations counterfeiting cascades, natural galleries with 
 balustrades and cornices of glittering stalactite — dazzle with their splen- 
 dor when lighted by the explorer's torch. 
 
 Caverns are also hollowed out by the action of the waves, as in 
 the case of Fingal's Cave on the island of Staffa, off the coast of 
 Scotland, worn out of columnar basalt {ia-smvW), an igneous rock. 
 In volcanic regions they may be formed by the passage of lava to 
 the surface, by the expansion of steam, or by the upheaval of strata. 
 Peculiar varieties of fish, sometimes blind, inhabit the waters of 
 caves. (On cavern life, see Skaler^s ^'Asj)eds of the &rth," p. 98.) 
 
 Caves have furnished important evidence as to the ancient history of 
 man, and possess an interest from the fossil remains sometimes found 
 beneath the incrustations of their floors. Cavern debris includes imple- 
 ments and weapons of bone and unpolished stone — awls, lance-heads, 
 and hammers, of flint ; bone needles, sculptured reindeer-antlers and 
 mammoth tusks, ornaments, etc. — mingled with the organic remains of 
 men and animals. These discoveries suggest that a race allied to the 
 Esquimaux, dwelling in caverns and subsisting by hunting, were co- 
 existent, in certain countries, with the mammoth, the woolly rhinoceros, 
 and the cave-bear. {See Dawkins's " Cave-Hunting.") 
 
 liOst River-s. — In some localities, particularly in the Appa- 
 lachian Mountains of North America, rivers have dissolved passages 
 for themselves through mountain-ranges, plunging into the range 
 upon one side, and reappearing wpan the other as huge springs. In 
 other places, rivei's sink abruptly into the earth, and, so far as 
 known, do not reappear, but pursue their courses miderground. 
 These are known as Lost Rivers. Caves are sometimes the passages 
 of subterranean streams. A river plunges into the mouth of the 
 Adelsberg Grotto, and emerges on the opposite side of the mount- 
 ain some eight miles distant. 
 
 Q,uestions. — How have the irregularities of the earth's form been explained ? 
 What is relief ? State the total relief of the earth in miles, and the pro- 
 portion between that relief and the earth's radius. Describe the move- 
 ments of the earth's crust, and the effects of erosion. State the area 
 of the earth's surface, and the proportion covered by water. Account 
 for the difference between the volume of the sea and that of the land 
 above sea-level. Under what circumstances might there be no land ? 
 Show by diagram the hemispheres of greatest and least land. Illustrate 
 the relation between Geology and Physical Geography by reference to the 
 distribution of land, and the change of physical features. 
 
 What are oceanic valleys ? Describe the bed of the sea. What are conti- 
 nents ? Classify islands. Specify points of resemblance between the great 
 bodies of land. Characterize the several varieties of plains. Describe a 
 caflon ; , a tundra ; a prairie-region ; a desert ; llanos, pampas, and selvas ; 
 
 steppes ; swamps, and salt marshes. Present the geological characters 
 of the different kinds of valleys. What are downs ? barrens ? 
 
 What are mountains ? Describe a mountain-system. What can you say of the 
 height and slope of mountains ? What is the geographical axis of a con- 
 tinent ? Explain the formation of a water-gap. Why are trees found on 
 mountains ? What is the timber-line ? The snow-line ? Would the 
 earth be more valuable to man, or less so, if there were no mountains on 
 its surface ? 
 
 What are caves, and in what rock are they most common ? Explain the prin- 
 ciple of their excavation; the formation of stalactites and stalagmites. 
 Describe a grotto. What remains are found in caverns ? 
 
 THE JMERICJJV COMTIJfEJ^T. 
 
 The American Continent consists of two parts, North 
 America and South America, connected only by a narrow neck of 
 land, known as the Isthmus of Panama. Each of these parts is 
 roughly pear-shaped, the broader portion being toward the north, 
 while southward each tapei-s to a point. 
 
 America has a total area of about 16,300,000 square miles, of 
 which it is estimated that 9,400,000 belong to North America and 
 6,900,000 to South America. 
 
 The Atlantic Coast of North America is for the most 
 part uneven, affording numerous excellent harbors. The extreme 
 northern part is bold and rocky, distinguished by points project- 
 ing far into the sea, and fringed with islands. Its character changes 
 in the neighborhood of Massachusetts Bay to a low, sandy, or marshy 
 shore, vi'ith a line of outlying sand-shoals. Between the shore and 
 these bars are coast swamps or open lagoons, which are becoming 
 slowly filled with the deposits of the streams. This form of coast 
 extends, with slight interruptions, nearly to the southern extremity 
 of North America. (For a description of an ocean-beach, see Tho- 
 reaifs " Cape Cod,^^ p. 51.) 
 
 On the Pacific Side, the coast is quite simple, with very 
 few harbors, as far north as the northern boundary of the United 
 States. At this point, its character changes abruptly. The coast 
 of British Columbia and Alaska is bold and rugged in the highest 
 degree, with a network of fiord-like bays and inlets, separating 
 mountainous islands and promontories. Through these narrow 
 arms of the sea one may sail for hundreds of miles, amid mountains 
 rising abruptly from the water's edge for thousands of feet. 
 
 The coast-line of the southern half of the continent presents little of 
 the variety of the northern. On both sides it is broken by few indenta- 
 tions. Only at the southern end of South America, where the range of 
 the Andes sinks into the sea, does the coast become broken and fiord-like. 
 
 In general outline, the relief of the two parts of the American Conti- 
 nent is strikingly similar. In each, the western portion consists of a 
 long plateau, crowned by mountain-ranges, and extending northward 
 and southward to the ends of the continent and westward nearly to the 
 Pacific Ocean. In each, the central portion is a broad depression or 
 valley, consisting of plains, prairies, lakes, and swamps, which is limited 
 on the Atlantic side by a secondary system of mountains, shorter, less 
 high, and less continuous, than that on the west. 
 
 Section of North America prom West to East, about Parallel 46 ' 
 
 Section of \orth America, adoct Parallel 20''. 
 
NOKTII AMERICA. — THE WESTERN PLATEAU. 
 
 23 
 
 North America.— The Western Phiteau.— lu North 
 America, the great western plateau, kiiowu as tlie Curdilleraii or 
 Koeky Mountain Plateau, is broadest and highest in the central 
 part of the United States. Here it stretches from Colorado west- 
 ward into California, having a breadth of over 800 miles, and 
 ranges in height from -1,000 to 10,000 feet above the sea. North- 
 
 wai-d it gradually decreases in height as well as in breadth, 
 western border follows the 
 Pacific coast, while the east- 
 ern inclines toward it. At 
 the northern boundary of 
 the United States, the pla- 
 teau is not more than 4,000 
 feet above the sea ; about 
 the heads of Peace River, 
 in British Columbia, it is a 
 thousand feet less; and, as 
 a well-defined geographical 
 feature, it disapjjears a short 
 distance farther north. 
 
 Southward also the pla- 
 teau diminislies in height, 
 but its breadth does not de- 
 crease until after the Mexi- 
 can boundary is passed. In 
 Mexico, hemmed in between 
 the Gulf of Mexico and the 
 Pacitie, it narrows rapidly 
 with the decreasing breadth 
 of the continent, but at the 
 same time it increases in ele- 
 vation, as if what it lost in 
 breadth it gained in height. 
 In central Mexico, its alti- 
 tude ranges from 7,000 to 
 8,000 feet. Interrupted by 
 a break at the Isthmus of 
 Tehuantepec, it passes east- 
 ward into the Central Amer- 
 ican states, its dimensions 
 rapidly decreasing, until in 
 Nicaragua the plateau dis- 
 appears. 
 
 This great plateau supports 
 many ranges of mountains, 
 and contains numerous valleys, 
 stretching for huudi-eds of miles, 
 
 The Climate of this 
 
 The 
 
 
 
 found only on the mountains, while some of these even are bare. 
 In certain regions the dryness is so great that the surface is a true 
 desert, as in many parts of Utah, Nevada, Arizona, and northern 
 Mexico; while over most of the country the vegetation consists 
 mainly of sage-l)rush, cactus, grease-wood, and Spanish-bayonet, all 
 of which are characteristic of arid regions. The soil is frequently 
 white and glistening with alkahne efflorescences. 
 
 ^_^^^_^^^_^^_^^_^_^_^_^^^__ A large part of the sum- 
 
 mit of this plateau is drained 
 neither to the Atlantic nor the 
 Pacific Ocean. The streams 
 which flow down from the 
 mountains are either absorbed 
 at once by the thirsty soil, or 
 collect in lakes which havo 
 no outlet, and from which the 
 surplus water is removed only 
 by evaporation. This is known 
 as the Great Basin. 
 
 The Mountain- 
 Kanges of the West- 
 ern Plateau. — Nearly all 
 the mountain-ranges capping 
 this plateau trend parallel 
 to its general course — i. e., 
 nearly north and south. The 
 highest and most important 
 of them crown its eastern 
 and western edges. Thus, 
 upon the western border, in 
 the United States, are the 
 Cascade Kange, a line of 
 extinct volcanoes, of which 
 Mount Piainier (14,-^1: feet) 
 and Mount Shasta (l-4,4-i2 
 feet) are the highest peaks ; 
 and the Sierra Nevada, with 
 Mount Whitney (14,898 
 feet). Upon its eastern bor- 
 der are the Wind River 
 Mountains, with Fremont's 
 Peak (13,790 feet); the Col- 
 orado Range, with Lonar's 
 
 Peak (14,271 feet), 
 
 and 
 
 Relief Map of North America. 
 
 In some parts are extensive plains 
 with a dull uniformity of surface. 
 
 Plateau, when considered as a 
 
 whole, is arid. It is true that in the northern part of British 
 Columbia there is ample rainfall for the neetls of forests; but 
 southward the rainfall decreases, and over nearly all that part of 
 the plateau lying in the United States and Mexico, forests arc 
 
 Pike's Peak (14,147 feet); 
 
 and the Saugre de Cristo 
 Mountains, with peaks exceeding 14,000 feet in height. In Mex- 
 ico are the volcanoes of Orizaba [<_)-rc-zah'ba) (18,314 feet) and Po- 
 pocatepetl {po-po-kah-tay-])etV) (17,784 feet) ; at the other extreme, 
 near the Alaskan border, in Canada, is Mount Logan (19,500 feet) 
 and also Mount St. Elias (18.010 feet). 
 
 The highest peak in the United States (exclusive of Alaska) is Mount 
 Whitney. A short distance southeast of it lies Death Valley, part of 
 
 
 ■^ ., <^ k 11 •' M (An/ )i t a i /P^. Vn 
 
 i- If/.. Denver «, ,, „/ "V(T.(.ur/" /, ^ '•-''' 
 
 ~ ? ■*■■ c 
 
 ^ -C ■*.' * « 
 
 -% 
 
 4 
 
 null* .Iffa Donver „„, „, 'V. 
 
 TED STATES 
 
 DOMfNION OF CAN4D4 
 
 Skction through thk Middle of Noktu America, with Comiarativk Hkiuuts of Mountains. 
 
24 
 
 THE GREAT VALLEY AND THE APPALACHIAN SYSTEM. 
 
 which is 100 feet below sea-leveL This region presents the sharpest con- 
 trasts of elevation thus far known in North America. Near the mouth 
 of the Colorado is a limited desert region, 300 feet below the sea. 
 
 The Great Valley of North America. — Eastward from 
 the summit of the Rocky Mountain Plateau, the country slopes 
 gently and almost impercepti- 
 bly downward. In the United 
 States and the southern part 
 of Canada, the slope is gen- 
 erally treeless and bears little 
 vegetation except a sparse 
 growth of grass, with a few 
 other plants found only in arid 
 regions. This slope is the 
 Great Plains, "a monotonous, 
 rolling, treeless expanse." 
 
 Farther northward and 
 eastward, as the soil and at- 
 mosphere grow moister and 
 the rainfall becomes greater, 
 trees begin to appear, and the 
 covering of the country' grad- 
 ually changes to a forest as the 
 middle of the Great Valley 
 of North America is reached. 
 
 This valley stretches from 
 the Gulf of Mexico to the Polar 
 Sea. Indeed, the Gulf itself may- 
 be considered as a part of it, 
 which, lower than the rest, has 
 filled with water. The southern 
 portion is drained by the Mis- 
 sissippi. Farther northward the 
 waters pass through the chain 
 of the Great Lakes to the 
 St. Lawrence, and still farther 
 north the rivers flow into Hud- 
 son Bay and the Arctic Ocean. 
 
 The surface of this great val- 
 ley is in the mam level or slight- 
 ly undulating. A few groups 
 of hills occur, as in Missouri, 
 Arkansas, and Michigan. 
 
 The Appalachian 
 Mountain System. — To- 
 ward its eastern border, the surface of the Mississippi Valley be- 
 comes more broken, and soon rises into the mountains of the Ap- 
 
 Relief Map of Socth America. 
 
 palachian System. This system commences in northern Alabama, 
 and runs northeastward, terminating in Canada. It is by no means 
 equal to that in the west, being narrower and less than half as high. 
 Its loftiest peaks are Mount Washington, of the White Mountains 
 (6,293 feet), and, in the southern part. Mount Mitchell, in North 
 
 Carolina (6,707 feet). 
 
 From the A2:)palacliian 
 Mountains eastward the coun- 
 try slopes gi'adually to the 
 sea, forming what is known 
 as the Atlantic Plain. 
 
 Continental Islands 
 of North America. — In 
 
 the northern part of Nortb 
 America, there is a group of 
 large, desolate islands stretch- 
 ing northwai'd beyond the 
 Arctic Circle, such as Banks 
 Land, Melville Island, the 
 Parry Islands, and othei's. 
 These form properly a part 
 of the great interior plain or 
 valley of North America, sep- 
 arated from the rest of the 
 continent by shallow arms of 
 the sea. Beyond them, east 
 of Baffin Bay, lies the great 
 island of Greenland. 
 
 Between North and South 
 America, and stretching east- 
 wai'd into the Atlantic, is a 
 group of islands, known as 
 the West Indies. The prin- 
 cipal members of this group 
 are Cuba, Ilaiti, Jamaica, and 
 Puerto Rico ; the smallest 
 are mere rocks rising from 
 the sea. 
 
 South America. — 
 
 The Andes. — In South 
 
 America, the great western 
 
 plateau, known as the Andean 
 
 Plateau, is much narrower than the corresponding feature in North 
 
 America, and borders the Paciiic coast much more closely. The 
 
 Section of SoniH America along the Eqdatob. 
 
 Section from the Chincha Islands to Kio Jancif-o. 
 
 20,001) fil- 
 ls, 000 
 
 10,000 
 
 5,000 
 
 ■■■?■■* 
 
 f/?.. 
 
 "S 
 
 
 
 
 A R n E N T I N 
 
 R E P U B L 
 
 VENEZUELA 
 
 ^j-.-o"-.... 
 
 
 ,Carll>bea7i Sm'Hkl 
 
 M.oori 
 
 ■>■■ lOjOCO 
 
 j:;;- 5,000 
 
 ,0 
 
 Section through the Middle of Sooth America, with Comparative Heights of Moumains. 
 
SOUTH AMERICAN R A NG ES. — H I G II L ANDS OF ASIA. 
 
 25 
 
 ranptes wliich crown it are fewer in number, while the peaks reach 
 nuich greater altitudes. Many of the highest of these are active 
 volcanoes. 
 
 Near the southern end of South America, the mountains become 
 partially siibmers-ed, producing', on the western side, a fiord-like coa.st. 
 Tlirou<;;h Chile, the Andean System gradually increases in altitude ; 
 while still farther north, in Peru, Ecuador, and Bolivia, it reaches its 
 greatest breadth and height. Here it consists in the main of two parallel 
 ranges, standing upon the opposite edges of a high plateau, from 100 to 
 2,")0 miles in bi-eadth, and from 10,000 to 13,000 feet in height. These are 
 connected by occasional cross-ranges, and are flanked by numerous 
 short branches, especially upon the eastern side. As we approach the 
 Lsthnuis of Panama, the mountains become lower, and are divided into 
 several ranges, one of which runs along the isthmus as a chain of low 
 hills, but a few hundred feet above the ocean, while others extend north- 
 eastward to the shores of the Caribbean Sea. 
 
 The passes of the Andes are steep and dangerous ; some of them, near- 
 ly three miles above sea-level, can be travelled only by mules and llamas. 
 
 The highest peak of the Andes, and also the highest summit in 
 America, is Aconcagua {ah-kon-l-ah'gumh), in Chile (23,290 feet), 
 formerly regarded as an extinct volcano. Farther north are the 
 Nevada de Sorata {so-rah'tah) (21,286 feet), Illimani {ed-ye-mah'ne) 
 (,21,149 feet), and Chimborazo {chiia-ho-rah'zo) (21,4i'-i feet), be- 
 sides scores of others of almost equal elevation. (Ou the geological 
 history of South America, the rise of the Andes and the creation of 
 the Amazon, see Ortoti's ^^The Andes and the Amazon" jp. 111^.) 
 
 While most authorities represent Mt. Aconcagua, in Chile, as the 
 loftiest peak not only of the Andes but of America, recetit surveys assign 
 to peaks of the Bolivian mountains a somewhat greater height. An 
 altitude of 24,812 feet is claimed for Mt. Illampu. 
 
 The Eastern Ranges of South America. — On the east- 
 ern side of South America, stretching across the United States of 
 Brazil, is a system of mountains, consisting of several ranges run- 
 ning in a direction nearly parallel to the coast, and separated from 
 one another by broad valleys. Neither in height nor in length are 
 these mountains to be compared with the Andes. They contain 
 some peaks exceeding 6,000 feet in altitude. 
 
 The Great Valley of South America consists, in its 
 northern part, of the Valley of the Amazon. Unlike the corre- 
 sponding feature in North America, the Andean Plateau has no 
 long eastward slope, but descends steeply to tlie Amazon Valley, 
 which is everywhere, even at the base of the mountains, but slight- 
 ly elevated above the sea. This valley is a low plain, well watered 
 and covered with dense, impassable Silvas already described. 
 
 Proceeding southward from the Valley of the .Amazon, we pass over 
 a plateau-like divide into a drier region. The forests become less dense, 
 and gradually the country changes to prairie, and thence to arid plain — 
 the Pampas of South America, where forests are unknown, and where 
 agricultm-e is, for want of rain, impossible. Over these plains, covered 
 with short grasses, range countless herds of cattle, the care of which 
 forms the principal occupation of the civilized inhabitants. 
 
 Owing to the absence of rain, the narrow strip of country lying 
 between the Andes and the Pacific Ocean is, except near its northern 
 and southern extremities, nearly or quite a desert. 
 
 EUR.1SIA. 
 
 The Eastern Continent consists of two parts— Eurasia and 
 Africa, connected only by the narrow Isthmus of Suez. Eurasia is 
 frequently divided into Europe and A.sia, but the line of division is 
 an imaginary one, and there is no physical reason for so drawing it. 
 
 Eurasia has an area of 20,500,000 square miles, or about 
 two-iifths of the total area of the land-surface of the globe. It 
 extends over 200 degrees of longitude, and from the Equator 
 nearly to 80 degrees north latitude. It has a very irregular shape, 
 which can not he simply characterized, with numerous great penin- 
 sulas and capes projecting into the sea on all sides, such as Scandi- 
 navia, Spain, Italy, Arabia, India, Siam, Corea, and Kamchatka. 
 Its shares are everywhere indented with bays and arms of the sea, 
 and fringed with continental islands. 
 
 The Highlands of Asia. — In its relief, Eurasia presents 
 no such simple picture as America ; and its low plains, plateaus, and 
 mountain-ranges, do not so readily fall into a SA'stem. Its apex is 
 in its southern part, where stands the Plateau of Thibet {tih'et), 
 13,500 feet high, hemmed in by the Ilbnalayas on the south, and 
 by the range known as the Kuen-Lun (kiren-Ioon') ou the north. 
 This is the highest extensive plateau on the globe. It is an arid 
 region, almost barren, with a very severe climate. Its surface is 
 diversified by mountain and valley, and contains numerous great 
 lakes, many of which liave no outlets. The mounttiins limiting it 
 ou the south are the highest ou the globe. Among their peaks 
 are Mount Everest, whose summit is the culminating point of the 
 earth's surface, reaching an altitude of 20,0(12 feet; Dhawalaghiri 
 {dor-wol-a-gher're) (26,820 feet), and many others exceeding 20,000 
 feet. The Kuen-Lun is but second in height. 
 
 From this great center of elevation, there stretches northeastward 
 toward Bering Strait and westward to the Persian Gulf and Arabia, a 
 series of great plateaiis, which diminish gradually m height as they 
 recede from Thibet. They form a broad line of elevation near the 
 southern and eastern borders of Asia. Toward the northwest there is a 
 rapid descent to the level of low plains. These plateaiLS are crowned by 
 numerous mountain-ranges, many of them of great altitude, here standing 
 so close together as to divide the country into an alternation of mount- 
 ain and valley, and there leaving broad expanses of plam or desert. 
 
 Desert of Gobi. — Examining this region of high plateaus 
 in greater detail, we find that north and northeast of the Plateau 
 of Thibet, and separated f i-om it by the Kuen-Lun, is the Desert 
 of Gobi {go'he), the great central desert of Asia. It lies at an alti- 
 tude of from 2,000 to 6,000 feet above the sea, and is intersected 
 by numerous mountain-chains, some of the peaks of which are 
 known to reach altitudes of from 10,000 to 12,000 feet. Its east- 
 ern border bears the Khin-Gan {Hn-gahn') range, and on the north 
 it is limited by the Yablonoi, Altai, and Thian-Shan (iee-akn'shan) 
 chains. The latter, which is sometimes known as that of the Ce- 
 lestial Mountains, is hardly inferior in height to the Kuen-Lun, 
 some of the peaks being said to exceed 20,000 feet. 
 
 J,,/^n lit' ^V:,oj\ 
 
 M h 
 
 ■'^ i 
 
 ■^" 
 
 !^j\ 
 
 ?-..^,.^... 
 
 OF THE GANGCS 
 
 THIBET 
 
 TURKESTAN 
 
 ERIAN PLAIN 
 
 ■■^SSjOM 
 ■-20,000 
 
 15,000 
 
 ■10.000 
 
 ■5,000 
 Sea Zttyl 
 
 Section of Asia from South to North, with Comparative Ueights of Mountains. 
 
26 
 
 HIGHLANDS OF EURASIA. 
 
 -^^ 
 
 ^ -S# 
 
 
 
 
 i^p-.^i%. 
 
 Relief Map of Eukasia. 
 
 Nortli of the Desert of Gobi lies a third plateau, which is 
 limited on the north by the Altai Mountains ; and beyond this, 
 northeastward, extends a series of ranges, of gradually decreasing 
 altitude, nearly to Bering Strait. 
 
 Northward and northwestward from the Altai Mountains, a vast plain 
 stretches to the shores of the Arctic Ocean. This plain, low, level, or 
 undulating, includes the steppes of Siberia, which pass into tundras in 
 the nortli. It has an arid, arctic climate, with great extremes of heat 
 and cold. Vegetation is scanty, consisting mainly of grasses and shrubs. 
 
 Plateau of Iran, etc. — Passing westward from the great 
 Plateau of Thibet, we encounter a series of plateaus of less height, 
 extending to the shores of the Mediterranean" Sea. The southern 
 limit of 'these plateaus follows the shore of the Arabian Sea and the 
 Persian Gulf. They comprise Afghanistan, Baluchistan, Persia, 
 Armenia, and Asia Minor, the northern limit being outlined by the 
 south shores of the Black and Caspian Seas, and by a liigh range 
 of mountains running east from the south shore of the Caspian, 
 known in different places as the Plindoo-Koosh, Paropamisan {pah- 
 ro-j)ahr^me-sahn'), Elburz {el-hoors'), and Taurus ranges. These vary 
 in height from 10,000 to 12,000 feet, and culminate in the lofty peaks 
 of Demavend (18,800 feet) and Mount Ararat (over 17,000 feet). 
 
 The elevations of these plateaus vary from 2,000 to 8,000 feet, 
 being generally highest toward the east and lowest westward. 
 
 The eastern portion of this plateau region, comprising Afghan- 
 istan, Baluchistan, and Persia, is in part a desert. The climate is 
 severe, with great extremes of heat and cold. Kainfall is slight, 
 and at a distance from the mountains there is but little running 
 water. In the western part, including the plateau of Armenia and 
 Asia Minor, the climate is more humid and the soil less sterile. 
 
 Another plateau of considerable extent, though not of great eleva- 
 tion, is that of Arabia. It covers nearly all of the peninsula of that 
 name, and is mainly a dry, hot desert, intersected by ranges of low 
 mountains. 
 
 Between the Caspian and Black Seas stretches the short but rather 
 lofty Caucasus Range, culminating in Mount Elburz, 18,570 feet. 
 
 Tlie Highlands of Evirope. — The plateau of Armenia and 
 
 Asia Minor, interrupted by the shallow Black Sea, continues west- 
 ward and spreads over the southern part of Europe as far as the 
 Atlantic Ocean. An offshoot to the south determines the position 
 of Turkey and Greece, while another to the north is cut by the 
 water-gap of the Danube and bends eastward and then northwest- 
 ward in the Carpathian Range. Two parallel ranges are separated 
 
LOWLANDS OF EURASIA. 
 
 I\v the Adriatic Sea, most of wliicb is exceedingly shallow, and 
 are then joined in the production of the Alps proper, which 
 attain their greatest altitude in Mont Blanc, 15,784 feet in 
 height. These include several ranges, trending nearly east and 
 west. On account of their proximity to the densely populated 
 and highly civilized regions of Europe, they are probably the best- 
 known mountains in the world. 
 
 The Jura, consisting of parallel ridges inclosing narrow valleys, 
 and the Cevennes {sai/-ven), with its extinct volcanoes, are lower 
 ranges, the latter reaching almost to the Pyrenees. South of the 
 Pyrenees, which are but little less lofty than the Alps, the plateau 
 of Spain is traversed by a number of minor ranges, determining it 
 as the most western part of the continent of Eurasia. (On Alpine 
 sculpture, the conformation of the A1])S, and an inquiry into the 
 forces by which the Swi.ss mountains were elevated, consult Pro- 
 fi'Ksor TijiidaU's '^Ilours of Exercise in the Alps" p. 221.) 
 
 In tlie north of Europe are 
 the Dovi-e field (fe-eld') Mountains, 
 forming the axis of the Scandina- 
 vian Plateau from .3,000 to 6,000 feet 
 in lieiglit. The surface of this is 
 much broken, particularly on the 
 west, where the coast-line is jagged 
 and i3reci])itous, being cut into a 
 great number of fiords. The slope 
 is more gentle toward the east. 
 
 15,000 
 10,000 
 5,000 
 
 Section of Europe from North to South, showing Comfaratite Heights of the 
 Trincital Modntain-Chains. 
 
 Great Britain, the largest island of Europe, is traversed by a mount- 
 ain-range from south to north, which in northern Wales culminates in 
 the beautiful peak of Snowdon (3,.571 feet). There is a brauch range 
 running parallel to the east ; wliile farther north, the Grampian Hills, 
 intersecting Scotland, contain among their numerous picturesque sum- 
 mits Ben-Nev'is (4,:5t)8 feet), the highest mouutaiu in the British Isles. 
 
 The Lowlands of Evirasia. — The Great Siberian Plain 
 stretches from Bering Strait toward the southwest as far as 
 the Caspian Sea. Tiie insignificant Ural Range (who.se highest 
 summits are hardly 6,000 feet above the sea), trending north- 
 ward to the Arctic Ocean, produces a slight interruption, beyond 
 which the low plain extends westward to the Atlantic, being 
 limited on the south by the Alpine Highlands and on the north- 
 west by the Scandinavian Plateau. Over its western area it is 
 
 partly covered by the shallow 
 Baltic Sea. 
 
 AVith the exception of Scan 
 dinaNna and the Mediterranean 
 countries, Europe consists of 
 plains but slightly elevated 
 above the sea ; and a small area 
 along the coast of Holland is 
 actually below sea-level. These 
 
 :ICA N.Jf^J^/ SARDINIA ^ CORStC*^-/ ITALY SWIT.'. GERMAN EMPIRE DENMARK^ SCAN D I N A V I A^O^* 
 
28 
 
 ISLANDS OF ECRASIA.— AFRICA. 
 
 plains are mainly well watered and fertile ; and the climate is not 
 severe except in the north. 
 
 In Asia, on the contrary, much the greater part is highland, 
 capped by thousands of mountains that lift their heads into the 
 region of eternal snow and inclose the loftiest plateaus in the 
 world. Aside from the Siberian Plain the only lowland regions 
 of noteworthy extent ai-e the valleys of the Euphrates and Tigris, 
 of the Indus and Gan- 
 ges, and the Chinese 
 Plain watered chiefly 
 by the Iloang 11 o and 
 Yangtze Kiang. 
 
 Asia has two regions 
 of remarkable depres- 
 sion. One is the basin of 
 the Caspian Sea, where 
 the Asiatic and Euro- 
 pean low plains unite 
 south of the Ural Mount- 
 ains. The level of the 
 water is more than 80 
 feet below that of the 
 Mediterranean. The oth- 
 er is the valley of the 
 Jordan, which is about 
 3,000 feet below the sur- 
 face of the country on 
 its two sides. This shal- 
 low river flows at a 
 depth much below sea- 
 level, and enters the 
 briny Dead Sea, the sur- 
 face of which is nearly 
 1,300 feet below that of 
 the Mediterranean. 
 
 Continental 
 Islands of Eura- 
 sia. — As might be in- 
 ferred from the very 
 broken coast-line of 
 Eurasia, the neighbor- 
 mg waters abound 
 in continental islands, 
 many of them of large 
 size. 
 
 On the Atlantic 
 side are found Great 
 Britain, Ireland, and 
 Iceland — the latter re- 
 markable as the seat of great volcanic activity. "Within the Medi- 
 terranean Sea are Sardinia, Corsica, Sicily, Cyprus, the Grecian 
 Archipelago, and the Balearic Islands, which are all distinctly con- 
 tinental. On the Arctic side are Nova Zembla, Spitzbergen, New 
 Siberia, and Wrangell Island. On the side oLthe Pacific is a line 
 of islands extending southward from Kamchatka, showing the posi- 
 
 tion of a submarine mountain-range parallel to the coast. These are 
 the Kurile Islands, the Islands of Japan, the Liu Kin [le-oo' he-oo) and 
 Philippine Islands, Celebes, Java, Sumatra, and Borneo. The last 
 two are very large. A still larger island. New Guinea, should be in- 
 cluded in the same group, but lies near the continent of Australia. 
 In the Indian Ocean, the island of Ceylon is separated by 
 shallow water from the peninsula of Ilindostan, of which it 
 
 is geologically a con- 
 tinuation. 
 
 EELiEr Map ok Africa, 
 
 AFRICA. 
 
 Africa was, prior 
 to the. completion of 
 the Suez Canal, a pen- 
 insula connected liy the 
 low, sandy Isthmus of 
 Suez with Eurasia. It 
 has been made artifi- 
 cially a distinct body 
 of land. In form it 
 is rudely pear-shaped, 
 its narrower extrem- 
 ity, the stem end, be- 
 ing toward the south. 
 Its area is estimated 
 to be 11,600,000 square 
 miles. The Equator 
 divides Africa into two 
 nearly equal parts ; 
 lying almost entirely 
 within the tropics, this 
 may fairly be called the 
 equatorial continent. 
 
 The Coast-Line 
 
 is extremely simple. 
 Indeed, the good har- 
 bors may be counted 
 on one's fingers. Its re- 
 lief is varied by moun- 
 tain, valley, and plain. 
 
 The Interior is 
 
 almost entirely a plain, 
 bordered on all sides 
 near the coast by ranges of hills or mountains. In the northern 
 part this plain is low, some of it being even below the sea-level. 
 The climate is arid, especially in the region comprising the deserts 
 of the Sahara, Egypt, and the Lower Soudan. 
 
 The surface of this region, while in the main level or undulat- 
 ing, is here and there broken by ranges of mountains, by plateaus 
 
 MOROCCO 
 
 SAHARA DESERT 
 
 .20,000 
 -15,000 
 10,000 
 
 Section throogh Africa from North to Sodth, with Comparative IIeights of the Principal Mountains. 
 
AUSTRALIA.— THE ANTARCTIC CONTINEXT. 
 
 29 
 
 and liill.-i. It is not outircly a desert. Althougli by far the greater 
 part is devoid of vegetation and is covered witii drifting sands and 
 bare rocks, tliere are occasional oases, some of wliicli are of great 
 extent, wliere the soil is watered by springs ; and in otlier places 
 rivers fertilize narrow belts of country along their courses. 
 
 Farther south, as the Equator is approached, the elevation inerea-ses 
 to a plateau, the mean temperature rises, and the rainfall is greater. lu 
 the equatorial region, the country is forest-clad. Here sevei-al of the 
 great rivers of Africa take their origin, and here are numerous vast 
 lakes and lake-like expansions of the rivei-s. The characteristics of cli- 
 mate anil surface prevail southward across the equatoi-ial belt ; but, as 
 the southern end of the continent is apjH'oached, the rainfall decreases. 
 
 The Moimtains of Africa. — Tlie ranges of mountains and 
 hills tliat liorder the platean follow the coast quite closely, leaving 
 on the shoreward side a comparatively narrow strip of land. I'or 
 the most part, they are not of great elevation. The loftiest of 
 them are in Abyssinia, and southward on the eastern side of the 
 continent. Almost under the Equator are the two highest African 
 mountains thus far known. Mount Kilimanjaro {l-il-e-mahii-jq-ro'), 
 nearly 20,000 feet, and Jlount Keni'a. The average height, how- 
 ever, of the mountains on the east wall of the plateau is not more 
 than 7,000 or 8,000 feet ; while those upon the west wall are even 
 lower, ranging generally from -1:,000 to (1,000 feet, the highest 
 being the Cameroons and the highlands, near the Gulf of CTuinea. 
 The west border of the Sahara Desert is its lowest part, the mean 
 elevation of this arid waste being about 1,500 feet. 
 
 At the northern and southern extremities of the continent also the 
 surface is crumpled into rugged chains, the Atlas Mountains extend- 
 ing about 1,500 miles, and the Snow Mountains overlooking the Indian 
 Ocean and terminating in the Cape of Good Hope. 
 
 Madajjascar is the only large island associated with Africa. 
 It is separated from the mainland by a wide but shallow channel, 
 and is very rugged, being occupied by two mountain-ranges which 
 trend parallel to those of the eastern African coast. 
 
 A USTRALIA. 
 
 Australia is tlie largest island, or the smallest continent, on 
 the globe. It has an area of about 3,000,000 square miles, thus 
 being about the size of the United 
 States, exclusive of Alaska. Its 
 coast-line, excepting on the north, 
 where it is somewhat indented 
 with bays and extended in capes 
 and promontories, is simple. 
 
 Australia consist^ mainly of 
 a low talde-land, elevated but a 
 few hundred feet above the sea. 
 The surface is rolling, or broken 
 by hills. Upon the east and west 
 sides of the continent, this plain 
 is outlined with ranges running 
 near to the coast and parallel with 
 it. The highest of these on the 
 east are known as the Australian 
 Alps. 
 
 The rainfall on the eastern 
 coast of Australia is ample for 
 the needs of agriculture ; but else- 
 where on the coast and every- 
 
 where in the interior it is scanty, so that vegetation is sparse, 
 except upon the mountain-sides. The great plain is mairdy cov- 
 ered with gra.sses and shrubs, the "bush" of the Australian, while 
 far in the ulterior are found extensive areas of desert. 
 
 
 Relief Map of Australia 
 
 Tffi: AJVTAJiCTIC COKTIJ^EXT. 
 
 South Polar RogrioiLS.— The last continental mass of land 
 is that surrounding the South Pole. Of this very little is known, 
 as it is impossible to penetrate inland. Parts only of the shore- 
 line have been explored ; near the coast are high mountains, such 
 as the active volcano Mount Erebus (12,306 feet), and Mount Ter- 
 ror (13,884 feet). {See map, 2>. 55.) 
 
 The whole land is covered witli great glaciers, from which 
 come the icebergs found in high southern latitudes. The climate 
 of the region about the South Pole being colder than that of the 
 North Pole, ice is encountered much farther away from it. Owing 
 to this fact, and to the difficulties connected with land-travel in 
 polar regions, a lai'ge area, nearly twice that of Europe, still re- 
 mains unexplored. 
 
 ftuestions.— What two parts constitute the American Continent ? Describe 
 them and state their areas. Characterize the eastern coast of North 
 America; the western coast; the coast of South America. Locate the 
 geographical axis of tlie New World. 
 Give an account of the western plateau of North .\merica; its surface, climate, 
 and vegetation. What is the Great Basin ? Describe the Great Plains; 
 the Great Valley of North America ; the Appalachian Mountain System. 
 Name the loftiest summits of the North American chains. What conti- 
 nental islands belong to North America ? Compare the eastern and west- 
 ern slopes of the Andes. Name the highest mountain in America ; the 
 highest volcano in the world. Describe the eastern ranges of South Amer- 
 ica ; the Valley of the Amazon ; the region between the Andes and the 
 Pacific. Com])are the physical characteristics of the two Americas. 
 Describe the contour of Eurasia ; the coast-line. Mention the details of the 
 Plateau of Thibet. Where is the great elevated region of Eurasia ? 
 Name the culminating peaks of the Himalaya chain ; the loftiest known 
 mountain on the earth. Describe the Desert of Gobi. By what ranges is 
 it bordered ? Describe the Siberian steppes ; the plateaus west of Thibet ; 
 the low j)lains and highlands of Europe. At what elevation are the great 
 passes across the Alps ? across the Pyrenees ? the passes from India to the 
 Thibetan Plateau ? Describe the Scandinavian Peninsula; the Southern 
 
 highlands ; the mountain- systems of 
 Great Britain. Explain the mode in 
 which hills are, in certain parts of Eu- 
 rope, formed near the sea. (Shifting 
 hillocks called Dunes, sometimes a 
 hundred feet or more in height, are 
 formed of sand washed up by the sea 
 or fresh-water lakes ; human ingenuity 
 has, in many instances, fixed the chang- 
 ing dunes, and converted them into 
 substantial barriers against the en- 
 croachments of the ocean.) (On the 
 origin of sand, sand-dunes, and sand- 
 |ilains, »ee Marsh's "Man and Nature,^' 
 p. JfSl.) Give an account of the conti- 
 nental islands of Eiu-asia. — What is the 
 shape of Africa ? its area ? the charac- 
 ter of its coast ? Descril)c the deserts ; 
 the equatorial regions; the mountain- 
 systems ; the continental island. Give 
 an account of the physical features of 
 Australia. Present an outline of the 
 position of the known lands in the Ant- 
 arctic Ocean, and state their physical 
 configuration so far as it is known. 
 
 }$ 
 
 
 
30 
 
 OCEANIC ISLANDS. — GEOWTH OF CORAL REEFS. 
 
 OCEAJfIC ISLAJVDS. 
 
 Characteristics. — Oceanic islands generally occur at a dis- 
 tance from continents, either isolated or in groups. An examina- 
 tion of the sea-bottom, however, shows that many of these islands 
 rise from submarine banks of great extent which are connected with 
 continents or but slightly separated from them. By reference to 
 the map, on p. 20, it will be seen that the banks from which they 
 rise are more or less connected with the neighboring great conti- 
 nental islands, as if all of them were the remains of a continent, 
 with its mountain-ranges 
 and valleys, that has sunk 
 below sea-level. 
 
 Oceanic islands present 
 far less variety than con- 
 tinental islands. The ma- 
 terial composing them is 
 generally volcanic. They 
 are often partly surrounded 
 with limestone, and some- 
 times almost entirely com- 
 posed of it. 
 
 As examples of volcanic 
 oceanic islands may be men- 
 tioned, in the Atlantic, the 
 Azores, Cape Verde, Madeira, 
 St. Helena, and Ascension Isl- 
 ands; in the Indian Ocean, 
 Kerguelen (kerg'e-len), St. 
 Paul, and New Amsterdam ; 
 in the Pacific, the immense 
 archipelag-o of Polynesia, 
 over 3,000 miles in length. 
 
 Coral Islands. — 
 
 The most interesting of 
 the oceanic islands are 
 those which owe their ex- 
 istence wholly or partly 
 to the agency of the coral 
 pol'j'p {many -footed^ a 
 minute marine animal that 
 spends its life in secreting 
 beautiful products, famil- 
 iar to us under the name 
 of coral (from two Greek 
 words, meaning maiden 
 of the sea). 
 
 Much of the coral used for 
 ornamental purposes comes 
 from the coast of Algeria, 
 Sicily, and elsewhere in the 
 Mediterranean, and from the 
 Red Sea, the Persian Gulf, 
 
 and the China Sea. There are many varieties ; but that which is most 
 highly prized for articles of jewelry is the red or rose pink coral of the 
 Mediterranean, obtained by means of dredging. This " precious coral " 
 was an important article of trade among the ancients. It was employed 
 by both Gauls and Britons to decorate their armor, and Roman chil- 
 dren wore charms made of it to protect them from the evil-eye. 
 
 The Coral Polyp may be regarded as a little sack of slimy 
 flesh, usually cylindrical, the opening of the sack constituting its 
 mouth. Around this are numerous delicate arms or tentacles, kept 
 
 continually in motion for the purpose of producing minute cur- 
 rents of water which enter the creature's body and are rejected 
 after yielding their mite toward its support. The coral polypi thus 
 closely resembles a flower (see p. lOT). 
 
 Sea-water contains lime carbonate Ln soltition ; this is extracted 
 and deposited between the inner and outer surfaces of the little 
 sack, forming a tube of limestone which thickens until the polyp 
 dies. Meanwhile this has propagated its young, and a mass of 
 limestone, perforated with fine holes, grows up gradually, sending 
 forth tree-like branches in every direction. Coral-trees ex-pand into 
 
 groves and forests of hme- 
 stone, many miles in ex- 
 tent, and alive with polyps 
 whose brilliant tints, shin- 
 ing through the clear wa- 
 ter, make the sea-bottom 
 appear almost like a ma- 
 rine flower-garden. Nat- 
 uralists have given to the 
 coral polyp the name of 
 zo'o-phyte {animal tohioh 
 grows like a plant). 
 
 A niimber of coral 
 families have been recog- 
 nized in a fossil condition, 
 and the ruins of ancient 
 coral architecture are scat- 
 tered among the rocks of 
 both continents. 
 
 There are numerous species of coral polyps, and the 
 forms and tints they assume are almost endless. " Some 
 grow up in the shape of leaves rolled around one another 
 like an open cabbage ; clustered leaves of the acanthus 
 and oak are called to mind by other species ; a sprouting 
 asparagus-bed by others. The mushroom is here imitated 
 in many of its fantastic shapes ; and mosses and lichens 
 add to the variety. Vases of polyp-flowers are common 
 about the reefs of the Pacific. The actinia may well be 
 called the asters, carnations, and anemones of the sub- 
 marine garden ; the tubipores (organ-pipe corals) literally 
 
 form its pink-beds ; and astraeas embellish with green and purple blossoms which stud the surface 
 like gems." In the engraving are shown the sea-fan, brain-stone, tree, rose, star, and cabbage coral. 
 
 Growth of Coral Reefs.— 
 
 The first polyp having begun 
 building its little monument 
 on a shallow bank of mud or 
 sand, the forest grows out- 
 ward and upward until its 
 branches reach the surface of 
 the water. Here the waves 
 are broken into foam by 
 them, so that the line of reef 
 is visible for miles as a white 
 sheet. But the branches are 
 themselves ground into frag- 
 ments by wave-action ; and 
 the irregular mass becomes 
 compacted into coral rock, on 
 the outer margins of which 
 the polyps continue to build. 
 The stronger waves break 
 off large pieces and pile them 
 up until they rise above the 
 average level of the sea. The 
 air continues the work of 
 disintegration, and soil is 
 formed. Dry coral sand is 
 still further piled up by the 
 wind, until an island is created, parts of which are beyond the reach of the 
 waves. This becomes a resting-place for sea-birds, and upon it is strajid- 
 ed vegetable matter that has drifted from the nearest land. At last the 
 seeds of the cocoa, date, and palm, the bread-fruit and the banana, find a 
 place for growth, and the coral island becomes bright with verdure. 
 
 Reef -building corals inhabit only clear, warm, salt water, thriving 
 best just below the surface. They cease to exist when the depth much 
 exceeds a hundi-ed feet. Mud or an intermixtiu-e of fresh water is in- 
 jurious or fatal to them ; hence, openings in coral reefs invariably occur 
 opposite the mouths of rivers or streams. 
 
FRINGING AND BARRIER R E E F8.— ATOLLS. 
 
 31 
 
 Fringing Reefs. — Although the process just described is a 
 
 guiicral oiiL', \>y far tlie greatewt ininiljer of coral reefs grow out 
 from the edges of volcanic islands or of continental masses. Where 
 the proper conditions of wannth and clearness of water exist, every 
 siK'h island is more or less completely siirroundeil hy a fri'mjiug 
 reef, which extends out at least as far as the limit of a hundred 
 and twentv feet in depth. Here the edge of the coral platform 
 slopes otT al)rui)tly. 
 
 Barrier-Reefs. — In many cases a volcanic island is sur- 
 rounded not only by a fringing reef, close to the shore, but also by 
 an outer ring of coral from which it is separated by a lagoon of 
 shallow water. Such an encircling coral formation is called a har- 
 rier-reef. Soundings taken close to the seaward margin of barrier- 
 reefs indicate great depths of water immediately beyond them, 
 t'oral reefs act as walls or dikes to detain the wash of the hills and 
 the fertilizing elements deposited by rivers, as well as to prevent 
 marine erosion along the shores off which they lie. 
 
 Atolls. — Barrier-reefs are sometimes found with no visible 
 volcanic island within. These are called n'tolh (from a Malayan 
 word, meaning vrcler). The slo])e of an ordinary island at the 
 water's edge is nsnally very gentle, rarely exceeding 5° or 0°. The 
 outer slope of an atoll is always steep, not unfrequently attaining 
 50° or 60°. Soundings upon these slopes indicate the presence of 
 coral mud at depths of many thousands of feet, and at no great 
 depth within the atoll. 
 
 Mode of Production of Atolls. — The explanation of the 
 mode in which barrier-reefs and atolls are formed is due to the labors 
 of Darwin, and has been confirmed liy the observations of Dana 
 and other geologists who have explored the islands of the Pacific. 
 
 Fringing reefs are found wherever reef-building corals exist ; 
 atolls, principally in the Pacific, over an area that is skirted with 
 regions where active volcanoes are seen, such as those of the Ha- 
 waiian Islands, New Zealand, and the East Indies. The ocean-bot- 
 
 Section of Cokal Island, showing Lagoon and Barrier-Reef. 
 
 torn over this area gives evidence of being strewed with volcanic 
 ashes, and seems to have been once active, but now to be studded 
 with extinct volcanoes. The central portion has long been gradu- 
 ally sinking, so that volcanic peaks, once high above the surface of 
 the sea, are deeply suljmerged. AVhen exposed, coral reefs formed 
 around them, as shown in the figure. 
 
 As the groimd slowly su1)sided, the corals continued to build 
 upward, those next to the shore being less vigorous than those at 
 the outer edges, on account of the muddiness of the water. A 
 lagoon, therefore, was gradually left between the shore and outer 
 part of the reef, while the sea-level encroached upon the sinking 
 island. 
 
 A barrier-reef around a small volcanic island is thus produced. 
 As the sinking continues and the coral on the outer part of the 
 
 reef keeps up with the searlevel, the entire peak disapjiears, and a 
 ring-shaped coral island is left, inclosing a shallow basin where 
 the summit had previously been. Thus an atoll rests upon a 
 submerged volcano. (On the strutiture and formation of coral 
 reefs, see Pr< feasor I)ana\ " Cvrals and Coral Jilaiuh" pp. 
 128, 222.) 
 
 Barrier-reefs are most abundant near the edges of a great sinking 
 area, and alolLs near the middle. The uorlhea.st shores of Australia are 
 thus still sinking, and a barrier-reef extends almost coutiuuously along 
 the coast for 1,200 miles, at an average distance of twenty to thirty miles 
 from the present shore-Uue. The depth of the inner channel varies from 
 ten to sixty fathoms; tliat of the outside sea sometimes exceeds 2,000 
 feet. West of the sinking area tliere are regions slowly rising, particu- 
 larly in tlie neighborhood of active volcanoes; and the remains of the 
 fringing reefs are found hundreds of feet above the present sea-level. 
 
 EEU.MUDA ISLANDS 
 
 8II'.iWlN(; m'TLVl.Sti 
 
 CORAL REEFS 
 
 
 LtO&E FLATS \ 
 VV S. 
 
 c 
 
 ,„9tt ""•'• ^"°"' 
 
 ST. GEORGE/ 
 
 St.Geurif. 
 
 Lonpitude West from nreenwlcTi 
 
 The Bermudas, a group of more than 100 islets fonned upon 
 a bed of coral, lie to the south of a bank or atoll, twenty-four miles 
 in length, and are inclosed on three sides by formidable reefs, in- 
 teresting as being farther from the Equator than any other living 
 coral formations. The channels of approach are extremely intri- 
 cate. The Bermudas are in a state of snlisidence. 
 
 The coral reefs at the southern end of Florda are barrier- reefs, 
 built up on the mud, fringing reefs being impossible immediately 
 in contact with such a shore. Wherever found, such reefs are 
 very dangerous to navigation, {t'unsult DarwirCs " On the Dis- 
 trihution of Coral Reefs.") 
 
 Beautiful as they are beyond description with their enameled foliage 
 and blue translucent seas, coral islands — in that their plants and animals 
 are limited to a few species, in that they contain no metallic deposits, in 
 that the commercial and agriculhn-al advantages derived from mount- 
 ain, river, and valley, are entirely wanting — have offered to then- 
 human inhabitants few opportunities of rising above the condition of 
 savagery. (On this subject, read Cooper's " Coral Lands.") 
 
 Questions. — What are oceanic islands ? Cite examples of volcanic islands in 
 tlie Atlantic, Indian, and Pacific Oceans. Define coral. Describe the 
 coral polyp, and coral reef-building. Is coral architecture confined to the 
 Neozoic Age ? 
 
 What are coral islands ? Fringing reefs ? Barrier-reefs ? Describe the 
 nature of an atoll. What is the theory of the circular formation of 
 atolls ? Explain the cause of broaches or openings into coral reefs. De- 
 scribe the Bermudas ; the Florida reefs. Account for the low condition 
 of man on coral islands. 
 
VOLCANIC PHENOMENA AND EARTHQ.UAKES. 
 
 Changes of the Earth's Sui'face. — It has already been 
 -bawn that in past geological eras the earth's surface underwent 
 many changes due to its cooling from a molten condition, all of 
 \rhich tended to make it uneven. The earth has been continually 
 diminishing in volume, though to what extent is unknown. Robert 
 Mallet has calculated that its present diameter is 189 miles shorter 
 than the diameter of the planet at the time solidification began ; if 
 so, the original crust must have been over 94 miles higher than the 
 present crast. 
 
 Unless the material composing the earth was absolutely uniform 
 in composition and original density, some portions of the surface 
 must have cooled, and therefore simk, faster than others. When 
 the cooling had proceeded sufficiently far to condense the hot vapor 
 of water, this must have gathered into the depressions and formed 
 oceans ; areas of slower coohng were left as continents. As the 
 contraction still further progressed with loss of heat, the sea-bottoms 
 must have increased in density and become rigid faster than the 
 continents. 
 
 The earth as a whole is now about 5^ times as dense as a globe of 
 water of the same size. If we take the density of water as a unit of com- 
 parison, the average density of the m.aterials composing the earth's ex- 
 posed crust will be expressed by 2i, and the density at the center by IG. 
 
 When an area is once covered with deep-sea water, the difference of 
 temperature between it and the earth's interior is sensibly increased. 
 Deep-sea soundings during the last few years have shown that the tem- 
 perature at the bottom of the ocean is uuiformly about 35° F. The 
 average temperature of the land is about 62° F. The conclusion is that, 
 not only in the past, but at tbe present day, the earth has been contract- 
 ing less rapidly on continental surfaces than on oceanic beds. 
 
 The Effect of Continued Contraction is to make the 
 external shell too large for the diminished interior, while at the 
 same time it is settling in consequence of its weight. The result 
 is, that the diifei-ent parts of the crust press sidewise against each 
 other with increasing force, until it yields and crumples at the 
 places of least strength. As might be expected, this crumpling has 
 always been greater on the less dense continental masses, particu- 
 larly near their edges, than on the sea-bottom. 
 
 Deep-sea soundings have shown that although the ocean-bottom 
 is div'ersified into "deeps" and "rises," there is nowhere such 
 abrupt change of level as is found on continents. This is time even 
 after making allowance for the fact that erosion on the continents 
 tends to make inequalities in elevated regions and to reduce them 
 in regions of depression. 
 
 While, therefore, continents are great areas left exposed in the pro- 
 cess of the earth's contraction, mountain-chains are secondary products, 
 made after the continents by the crushing of their weakest parts. The 
 continual tendency is for the oceans to become deeper, and the conti- 
 nents to become higher in comparison with the ocean-level, not only 
 because the continents are sinking less rapidly, but because they have 
 been crumpling more rapidly. The effects of such crumpling are antago- 
 nized by erosion ; but this does not interfere with the sinking of the 
 central parts of the great ocean-bottoms. 
 
 Slo^w Oscillations. — We have the best evidence that there 
 still exist great differences of temperature between the earth's sur- 
 face and its interior. There is also evidence that the surface is 
 rising in some places, and sinking in others, at least along the mar- 
 gins of the seas. 
 
 Regions of Elevation. — The western coast of South Amer- 
 ica was examined by Darwin through an extent of more than 
 
 2,000 miles. High up on the mountain-sides were found the evi- 
 dences of former washings by the ocean, such as shells, old beach- 
 lines, and corals. At Valparaiso, in Chile, the elevation has been 
 at least 1,300 feet, of which 10 feet was raised between the years 
 1817 and 1834. At Chiloe the rate has reached one foot a year. 
 Corals are found 3,000 feet above sea-level. A similar rise has 
 been noticed over 1,180 miles of the eastern shore. 
 
 Observations on the shores of Noi way have shown a steady rise 
 of one foot in twenty years in the northern part, the average being 
 one foot in forty years. Similar changes have occurred in Scot- 
 land, Iceland, Japan, the East and West Indies, and in volcanic 
 regions generally. {See map, pp. 38, 39.) 
 
 Regions of Depression. — The sinking of the earth's sur- 
 face in certain parts of the world is proved by the encroachment 
 of the sea upon its shores. The Atlantic coast-line of the United 
 
 States is steadily sinking. Along the coast of New Jersey, South 
 Carolina, and Georgia, the stumps of trees have been found stand- 
 ing vertically under the water many hundreds of yards from the 
 jjresent beach. 
 
 Similar evidences are found in the deltas {see 2). W) of many 
 great rivers, such as the Mississippi, Rhone, Ganges, Indus, and 
 Nile. 
 
 The coast of Holland has been depressed to svich an extent that much 
 of it is now below the level of the sea, from which it is protected partly 
 by natural sand-hills and partly by vast artificial dikes. The southern 
 coast of Greenland is sinking so rapidly that ancient structures have 
 become submerged, and the natives are careful not to build near the 
 water's edge. The east coast of AustraUa is also settling, along with a 
 lai'ge area of the Pacific Ocean, as shown by observation on coral islands. 
 The whole Australian Continent is low. 
 
 Regions of Alternate Elevation and Depi'ession. — 
 
 On the Italian coast at Naples are some columns of an ancient Ro- 
 man temple which was gradually submerged, probably after the 
 twelfth century of the present era, to the depth of 21 feet, and has 
 since been raised, along with the adjacent coast, to its former level. 
 At other points along the coast of Italy are many evidences of 
 alternate elevation and subsidence, all taking place so gradually as 
 to be imperceptible from year to year, and ascertained only by 
 measurement between long intervals of time. (On siibsidence and 
 elevation, see LyelVs " Principles of Geology,'''' vol. ii., p. 180.) 
 
 Temperature below the Earth's Siu'face. — The earth's 
 surface is subject to shght variations of temperature due to the 
 alternation of day and night, summer and winter, the greatest of 
 which do not extend to a depth of 200 feet. In the Mammoth 
 Cave of Kentucky, 70 feet below the surface, the temperature 
 throughout the year is 61° F. 
 
 The temperature of the earth's crust increases with increasing 
 depth, even in the frozen soil of Siberia. The rate depends upon 
 the nature of the ground, and has been found as rapid as 1° F. in 
 27 feet, as slow as 1° F. in 200 feet. The mean rate, determined 
 by observations in deep mines and artesian bore-h'oles, is 1° F. in 
 55 feet, or about 100° a mile. 
 
 It seems highly improbable that such a rate shoidd be uniform with 
 increase of depth and therefore increase of pressure. If it were, and if 
 tbe melting-point of known substances were not increased by pressiu-e, 
 the sohd shell of tbe earth's crust could not exceed forty miles in thick- 
 ness, one-bundi-edtb of the distance to the center ; beneath this limit, all 
 would be fluid. 
 
VOLCANOES AND VOLCANIC ERUPTIONS. 
 
 33 
 
 If tlH> intei'ioi' were gaseous or liquid, it would bo subjected to tidal 
 movements like the oceiiu. The pressure becomes inconc('iv:il)ly great 
 as the earth's center is approached, and the temperature nuist also be 
 inconceivably high. It will probably never be ascertained whether this 
 temperature is sulliciently high to prevent the interior from becoming 
 solid; and, if so, whethei- the rigidity of the crust is great enough to 
 i"csist completely all tidul disturbances. The earth's interior is probably 
 softened in some places, and quite neai- to the surface ai'e reservoirs from 
 which hot, pasty material is occasionally thi-own ; but we are compelled 
 to content ourselves with knowledge only of phenomena at the surface. 
 (On underground temperature and the condition of the interior of the 
 earth, see Fislier's " Physics of the Earth's Crust,'' pp. 1-28.) 
 
 Stroniboli rises from the sea-bottom to tlie height of 3,000 
 feet above sea-lovel. On the side, 1,000 feet below tlie sum- 
 mit, is tlie present crater, which may be approached with safety. 
 The bottom is traversed by interlatiiiig cracks through which 
 steam and various gases are continually rising. From larger fis- 
 sures, molten material like tar overflows and slowly rolls down 
 toward the sea, constantly sending forth steam . in its course. 
 
 VOLCA.YOES. 
 
 A Volcano is a mountain btiilt of material that has been 
 forced up in a hot condition through one or more openings in the 
 earth's crust. It is ofteu to some extent isolated, and is usually 
 roughly conical in sha])e. The openings, when the volcano is not 
 active, ai-e closed nearly to their edges, forming bixsins which are 
 called Craters. 
 
 Volcanoes have existed during all periods of the earth's history, 
 and many of those that have been active in the past are uow 
 extinct. Such are found in France, Germany, Asia Minoi-, and in 
 great numbers in the 
 western part of the 
 United States. 
 
 Of active volca- 
 noes, the majority are 
 intermittent, while 
 some are constcmt. 
 Vesuvius, Etna, and 
 Hecla, are examples of 
 the foiTuer ; Strom'- 
 boli is the best-known 
 instance of the latter. 
 
 Vesuvius was con- 
 sidered extinct until 
 A. D. 70, when the ter- 
 rible eruption occurred 
 that resulted in the en- 
 tombment of the cities 
 of Herculaneum, Pom- 
 peii, and Stabi*. Since 
 that time it has been in - 
 termitteut, and of late 
 years nearly always 
 active to a limited ex- 
 tent. Stromboli varies 
 in the intensity of its 
 
 activity, but has never been known to equal, in its eruptions, the vio- 
 lence of Vesuvius. Mount Etna, on the east coast of Sicily, the most 
 famous volcano in the world, is remarkable for the number of minor 
 cones scattered over its sides. A record of its eruptions has been kept 
 since the seventh century B. c, the frightful lava-torrent of 1669, 
 which overwhelmed the city of Catania, being among the most ter- 
 rible convulsions known. Of late years, Etna has been comparatively 
 quiescent. 
 
 Phenomena of an Eruption. — Volcanic action is best 
 
 understood by examining that of a constant, but not violent, vol- 
 cano like Stromboli. This is one of the group of the Lip'ari Isl- 
 ands, lyiug north of Sicily and composed of volcanoes, most of 
 which are now extinct. 
 
 CitATi i; OF Vesl'vids in 1756. 
 (From a drawing made at the time.) 
 
 Crater of Kilauea. 
 (From a pliotograpli in 1885.) 
 
 From others, steam is emitted in-egularly in sharp, ex- 
 plosive puffs. In the largest of the iissures, the' stiff, 
 hot, viscous mass is seen to heave sluggishly up and 
 down. A large, thick bubble rises upon its surface and 
 bursts with a loud explosion. The steam in its escape 
 carries fragments of hardening scum high into the air. 
 Part of this falls back' into the crater, and ])art is scat- 
 tered around, adding its mite to the pile that has thus 
 grown up 6,000 feet above its submarine base during the 
 course of untold centuries. 
 
 Stromboli is hence perpetually capped with a cloud 
 of condensed steam. At night this is illuminated with 
 the elare from the hot fissures below. Whenever a bub; 
 ble bursts, this light suddenly increases, and gradually 
 diminishes as the white-hot surface thus exposed cools 
 down to redness. The effect is comparable to that of 
 fog over an invisible and inconstant electric light, or 
 around the revolving lamp of a light-house. {ConstiU Professor 
 JucWs ''Volcanoes: What they are, and what they teach," 
 
 p. U.) 
 
 A volcano has never been seen to emit a bright flame or any visible 
 smoke as the result of combustion. It is in no sense a " burning mount- 
 ain," nor has brimstone any agency in producing its heat, though sul- 
 phurous gases are often included among the products emitted. It is an 
 immense terrestrial caldron, bubbling as it gives vent to overheated 
 steam, which rises from underground reservoirs of intensely hot, viscous 
 rock-matter. 
 
 If for any reason the communication with these reservoirs be inter- 
 rupted, the steam gathers, as it does in a closed boiler. Finally, its elas- 
 tic force becomes sufficient to blow up the entire floor of the crater in a 
 single outburst or a series of outbursts, and this is followed by the over- 
 
34 
 
 ERUPTIONS OF VESUVIUS AND KRAKATOA. 
 
 flow of great streams of lava. The sides of the mountain are split into 
 fissures ; and out of these, as often as from the crater, the hot streams flow. 
 
 Changes due to Eruption. — lu the time of the Eomans, 
 the top of Vesuvius was a depressed plain, overgrown with wild 
 vines, and surrounded by a rough and lofty rampart, a portion of 
 which still remains and is called Monte Somma. It once served as 
 a fortress for the besieged gladiator, Spartacus. A large part of 
 this plain, together with the southern half of its rampart, was blown 
 up in the violent eruption of 79 a. d., and a ragged pile of debris 
 left in its place. This was perforated by subsequent eruptions, 
 until in 1756 it presented the appearance of a series of ramparts 
 within ramparts. These 
 ia turn were subsequently 
 tilled up, and at last de- 
 stroyed in the great erup- 
 tion of 1822, which left a 
 huge cavity 1,000 feet deep 
 and nearly a mile in diame- 
 ter. Small cones were grad- 
 ually piled up again, to be 
 partly demolished by erup- 
 tions of greater violence 
 like that of 1872. The 
 present cone rises to the 
 height of 1,000 feet with- 
 in the half-inclosing; rins 
 of Monte Somma, and a 
 railway now winds up to 
 its summit. 
 
 Eruption of Vesuvius, 
 
 1872.— During- 1871, Vesuvi- 
 us was in a state of activ- 
 ity, wliich increased until, on 
 April 24, 1873, a violent erup- 
 tion began. From the crater, 
 and from innumerable fis- 
 sui-es, one of which extended 
 from summit to base, liquid 
 matter flowed. Three great 
 lava-floods rolled down the 
 mountain far beyond its base, 
 destroying houses and vil- 
 lages. Their course could he 
 distinguished by the thick vol- 
 umes of steam given off and 
 continuing to lift up minia- 
 ture volcanoes on the hard- 
 ened crust long after the sur- 
 face became cool. 
 
 From the crater, vapors 
 and rock - fragments were 
 
 thrown to the height of nearly four miles, in a series of detonations like 
 the heaviest of cannonading, that succeeded each other so rapidly as to 
 produce a continuous roar when heard at Naples. Before and during 
 the eruption, the ground, for miles in every du-ection, was in a constant 
 state of tremor. The cloud of suspended vapor and dust was strongly 
 electrified by the friction of the ejected materials. Bright flashes of 
 lightning played around the column, and the rolling of thunder was 
 added to the terrestrial cannonade. As the vapors condensed around the 
 particles of volcanic dust, heavy showers of muddy rain fell, deluging 
 the places that had not been reached by the hot streams of lava, or pelted 
 with the haU of falling stones. 
 
 Eruption of Krakatoa, 1883. — One of the most gigantic eruptions 
 recorded in history occurred on the 27th of August, 1883, in the Strait of 
 Sunda. between Java and Sumatra. After eight months of variable 
 
 Vesuvius in Eruption, as sees from Naples, April 26, 1872. 
 (From a photograpli.) 
 
 activity, a series of violent detonations began on the afternoon of 
 August 26th, continued throughout the night, and culminated on the 
 morning of the 27th. The play of lightning about the whu-ling column 
 of ascending dust and ashes was seen in Batavia, 94 miles away. Sun- 
 light was excluded by the thick cloud, so that midnight darkness con- 
 tinued throughout the day over an area 400 miles across, and the air 
 was gloomy to a distance of 1,000 miles. Trees seventy nailes off were 
 shattered by the weight of the falling mud, and Batavia was covered 
 with it to a depth of thi-ee inches during the hours of darkness. To ac- 
 complish this, it is estimated that volcanic dust must have been pro- 
 jected not less than 10 or 15 miles up, even beyond most of the atmos- 
 phere. Tbat it did reach this height is shown by the unexampled 
 oscillations of the barometer in all parts of the world, indicating a 
 
 series of air-waves that sped 
 seven times round the globe at 
 the rate of 700 miles an hour. 
 The explosions wei'e heard m 
 India and elsewhere over a 
 circle of 1,800 miles io radius, 
 with Ki-akatoa as a center. 
 The fall of dust was noted at 
 points 915 miles northwest, 
 1,200 mUes southwest, and 
 1,050 miles southeast. 
 
 By the two final outbursts, 
 most of the small island of 
 Krakatoa (krah-kah-to'ah)^ ly- 
 ing at the intersection of two 
 fissures in the earth's crust, 
 was hurled into the air ; and 
 the falling fragments formed 
 two new islands about seven 
 miles distant. The exposed 
 parts had, in succession, been 
 shot off till the remnant was 
 reduced to the water's level. 
 The sea then poured down 
 into the chasm, and millions 
 of tons of water miagled with 
 white-hot lava in titan throes 
 until the ocean gained the 
 mastery. Over the shore 30 
 mUes distant, waves 100 feet 
 high rolled \\it\i resistless en- 
 ergy, sweeping away every 
 tree, house, and living being. 
 Coral blocks, fi'om 20 to 50 
 tons in weight, were torn from 
 their beds and stranded two 
 miles inland. Upon the stifled 
 crater, after the eruption, the 
 depth of water was more than 
 1,000 feet, where previously 
 there had been an elevation 
 of 1,000 feet. 
 
 The finest dust from Kra- 
 katoa continued suspended in the upper atmosphere and was wafted over 
 a vast area, causing a peculiar red glow at the time of sunrise and sun- 
 set that was noticeable for many months. {Consult Report of the Kra- 
 katoa Committee of the Royal Society, ISSS.) 
 
 Among American Volcanoes must be remembered the 
 Mexican Popocatepetl {smoMng mountain), bearing upon its ice- 
 crowned sunnnit an enormous crater nearly a mile across and half 
 a mile in depth ; Jorullo {ho-rool'yo), forced up in a single night 
 (1759) from broad plains covered with sugar and indigo plantations, 
 to a height of nearly 1,700 feet ; and the Andean Cotopaxi, most 
 symmetrical of five active cones visible from the city of Quito, 
 standing out in snowy splendor against the equatorial sky. 
 
 ,ac 
 
LAVA, ITS COMPOSITION AND C H A K A CT K li I ST I CS. — VO LC A N IC CONES. 
 
 35 
 
 Most of the mountains of Iceland liave been volcanic, Hecla 
 being the best known of those that are now active. {Consult 
 Boi hiner's '■'■ Observations of Volcanic Erujdions iti Iceland.'''') 
 
 Products of Volcanic Action.^Of the gases emitted 
 from volcanoes, by far the most abimdant is steam. Others in 
 small (juantity, chietiy acid in character, accompany it. The steam- 
 blast, if violent, may carry oft" fragments of rock, as at Krakatoa. 
 But of the denser material, most comes from greater depths and 
 reaches the sm-face in a softened state. This is called Lava. 
 
 Composition and Characteristics of Lava. — Lava 
 consists of siHca, combined in various degrees with other sub- 
 stances known as hases, such as soda, alumina, iron, etc. If the 
 latter predominate, the lava is usually dark, easily melted, and 
 becomes glassy when cooled. If the silica pi-edominatcs, the color 
 is lighter, crystals are diffused through the mass, aud it is stiff and 
 viscous even when white hot. 
 
 Steam is often diffused through lava ; hence, when the lava 
 cools, it is full of bubbles. Pumice is glassy lava puffed with 
 minute bubbles which give it a white look and cause it to float. 
 Scoria is the name applied to crystalline lava, in which the bubbles 
 are generally larger than in pumice, giving it a rough, cindery look. 
 Fragments of it rubbing against each other produce volcanic dust. 
 This, when soaked with wati'r and compacted into a hard mass, is 
 called Tufa. 
 
 Lava is a poor conductor of heat. The surface of a stream of 
 it soon hardens into a rough crust, which protects that underneath 
 from rapid loss of heat. Thus protected, it remains sensibly warm 
 for many years. (On volcanic dust aud lava-streams, read GeiJcie's 
 ''Text- Book of Geology," j). »16.) 
 
 Structure of Volcanic Cones. — The majority of volca- 
 noes are built up of fragments of scoria and beds of tufa, piled 
 around an aperture which becomes choked. If the eraption is 
 violent, these fragments are spread far and wide, forming a broad 
 base. The slope is steepest near the crater, and diminishes near 
 the base. 
 
 The layers of scoria and tufa are partly overlaid by streams of 
 lava, which are covered with more scoria as the pile grows. After 
 a period of rest the resistance of the solidified crater increases, 
 until new eruptions cause the mountain to split. Lava is then 
 forced up and hardens in the fissures, forming dikes, or it may 
 overflow and spread in sheets. New craters are often started in 
 this way. 
 
 In the island of Ma leira a river has cut through the base of a 
 volcano at one side, revealing the internal structure very beautifully. 
 
 Calderas is a name given to certain volcanoes which are 
 made uj) entirely of lava cooled from a liquid state without being 
 broken up into scoria and tufa. In these the ejections are but 
 feebly explosive, and the activity is nearly constant. The lava 
 contains much potash and iron, being very thin when hot and 
 glassy when cold. 
 
 Tlie best examples of this class are the volcanoes on tlie island of 
 Hawaii {hah-wi'e), iu the Pacific Ocean. This island is made up of a 
 pile of lava. It is very g'eutle in slope, being 13,370 feet higli at the top, 
 from which the descent is at an average angle of only 6°. Near the 
 summit of the flattened dome Ls the crater of Mauna Loa. a great pit 
 over two miles wide, aud from 700 to 1,000 feet deep. In this the lava is 
 always hot ; it overflows once every few years, but more frequently es- 
 capes by spouting up from fissures on the sides of the mountain, through 
 which it is squeezed in great jets. 
 
 Another crater, known as Kilauea (he-low-aij'ri), exists about 10,000 
 feet lower on the side. Its greatest width is three miles, and its depth about 
 600 feet. Near the center is an inner pit 400 feet deep, in which the 
 bottom crust is in almost perpetual movement, like the liquid in a 
 caldron. Three areas in it are especially active, forming incandescent 
 lakes where the lava is ever boiliiiir aud bubbling. At intervals small 
 cones rise and bui-st, throwing th(> fiery spray from .50 to 100 feet into 
 the air. Occasionally, as at Matuia Loa, the whole vast crater fills and 
 overflows, or the lava bursts through the mountain-side, then sinks in 
 the crater, sometimes out of sight. {See " Science " for July 23, ISSG.) 
 
 ("liff-Section in the Island of Maheira, showing how a Composite Volcano is 
 BUILT cp OF Lava-Streams, Beds of Scoria, and Dikes. 
 
 On the Cth of March, ISSfi, Kilauea was unusually active. The fol- 
 lowing day the floor of the inner crater subsided, leaving an irregular 
 cavity two-thirds of a mile long, wide enough to embrace the three lakes, 
 and of unfathomed depth. Quiet and darkness reigned in the cavern 
 until June. The crater has since become fllletl as formerly. (See p. 33.) 
 (On Hawaiian volcanoes, read Cumming's "Fire Fountains.^') 
 
 Fissure Eiiiptions. — Although the passage from the crater 
 of an active volcano to the reservoir of lava below may be roughly 
 tubular, it seems probable that every volcano starts over a Assure. 
 If this be large enough, the lava is sqiteezed up through its eiitire 
 length and floods the country. Such an overflow covers more than 
 100,U00 sqitare miles on the great western plateau of the United 
 States, and is 3,0l)0 feet thick where cut by the Columbia River. 
 
 If the fissure be small, lava is first forced through its widest 
 parts; the rest becomes choked, and volcanoes are built over the 
 first vents. The Lipari Islands are a group of volcanoes on three 
 fissure-lines which radiate from a single point. Two of them, 
 Stromboli aud Yulcauo {rool-hih'no), are still active. The crater 
 of the latter has been shifted through six successive positions on 
 the fissure, each new crater destroying the northern wall of the 
 previous one. 
 
 Parasitic Cones. — When the volcano itself is split during 
 an eruption, the smalbr fissures serve as starting-points for minor 
 
36 
 
 CAUSES OF VOLCANIC A CTl O .V. — M I NO R PHENOMENA. 
 
 cones, which grow upon the main cone, and hence are called 
 parasitic. 
 
 •Linear Arrangement of Volcanoes. — Most of the 
 active volcanoes of the earth ai'e situated upon zones where the 
 crust seems to have been weaker than elsewhere, and along which 
 fissures in all possible directions are specially numerous. One of 
 these belts is continuous with the Andes, Cordillera, and Rocky 
 Mountain systems ; extends through the Aleutian, Kurile, Japan, 
 and Philippine Islands, New Guinea, and New Zealand ; and in- 
 cludes the volcanoes of tlie Antarctic Continent. Another reaches 
 througli the East Indian Islands, Southern Europe, the Azores, 
 Canary and West Indian Islands, and Central America. The 
 crossing points of these two zones in Central America and the East 
 Indies are specially subject to the most violent outbursts. 
 
 Other less distinct zones may be traced, but these two include more 
 than three-fourths of all the volcanoes known. 
 
 Of volcanoes not included in these zones, the Iceland group is the 
 most celebrated. Near the middle of Asia three volcanoes occur in the 
 Thian-Shan range, and another in the eastern part of Mong'olia. The 
 Hawaian volcanoes form another isolated group. (See Map, pp. 38, 39.) 
 
 Proximity of Volcanoes to the Sea. — With the ex- 
 ception of the Asiatic group, all known volcanoes are within a few 
 hundred miles of the sea. The Thian-Shan Mountains were once 
 at the edge of a great inland ocean which in Tertiary times {see p. 
 15) covered the districts where its remnants may now be found in 
 the Caspian and Ai-al Seas. This does not prove that the neigh- 
 borhood of sea-water is necessary to volcanic activity; but since 
 the greatest crumpling of the earth takes place along shore-lines, it; 
 might be expected that volcanoes would be most abundant in such 
 regions. (On the geographical distribution of volcanoes, consult 
 Fislierh "■Physics of the Earth? s Orust^'' j). 259.) 
 
 Number and Size of Volcanoes. — It is not known 
 how many active volcanoes there are upon the globe. The num- 
 ber is variously estimated at from 225 to 600, the majority of 
 which are on islands. The number of extinct volcanoes is far 
 greater. 
 
 Volcanoes vary in size from mere liillocks to mountains four 
 miles high. The depth of water in the neighborhood of Mauna 
 Loa is 18,000 feet. The height of this pile of lava above the sea- 
 bottom, therefore, exceeds that of the Himalaya Mountains above 
 sea-level. 
 
 Cavise of Volcanic Action. — All porous strata below a 
 certain level are saturated with underground water, which is pressed 
 by the overlying masses, and percolates even against great resist- 
 ance through the rocks. It is believed that water may thus flow 
 freely into volcanic vents, producing steam sufficient to account 
 for the observed explosions. 
 
 Aside from this, many volcanoes are near enough to the sea to 
 warrant the supposition that the percolation of sea-water may be 
 added to that of fresh water, especially where any great lines of 
 fissure are known to exist. 
 
 If water be sufficiently heated at great depths, it permeates the mass 
 with which it is in contact, but is prevented by the great pressure from 
 (lashing into steam until a certain temperature is reached, at which its 
 expansive force is sufficient to balance this pressure. The ground then 
 yields at the weakest point ; a crater is opened, and the consequent re- 
 moval of pressure causes the water to change into steam throughout the 
 whole mass of lava, which is blown out in a spongy condition. 
 
 But this explanation is not sufficient to account for the compara- 
 tively quiet forcing up of lava through fissures, as in the case of the 
 
 Hawaiian volcanoes, where there is little explosive action. The primary 
 cause of these eruptions is doubtless the shrinking of the earth's crust, 
 which produces pressure upon any liquid, viscous, or plastic layer within 
 it. Pressure is transmitted in all directions by a liquid, and hence the 
 crust yields over such a reso-voir, breaking into fLssures which transmit 
 the hot matter from below. Relief being thus gained, there is total or 
 partial cessation of activity until further contraction causes a repetition 
 of strain. 
 
 This general cause does not exclude the operation of other special 
 causes, such as the local production of steam. Probably all may operate 
 together, the outbui-sts of steam bemg most noticeable on cones of scoria 
 and tufa. 
 
 In confirmation of this view, it may be observed that great eruptions 
 are nearly always preceded by trembUng of the gromid and muf&ed sub- 
 terranean sounds. When an outburst occurs, it is followed by the lava- 
 flow, instead of being accompanied by it ; which shows that steam alone 
 is not sufficient cause for the upheaval of the lava. This flow in turn is 
 coincident with the cessation of undergroiuid thundering. 
 
 Lava-Keservoirs. — The ejection of lava is no proof of con 
 nection between the surface of the earth and any general liquid 
 interior. When Mauna Loa is active, there is no observable effect 
 on Kilauea ; and an eruption of Etna is not usually accompanied 
 with special activity either of Stromboli or Vesuvius. The conclu- 
 sion is, that each of these volcanoes has a separate reservoir. The 
 earth's contraction does not produce equal strain on all parts of the 
 surface ; hence neighboring volcanoes may exhibit very unequal 
 degrees of disturbance. 
 
 Relation of Volcanoes to Earth -Oscillations. — 
 
 Wherever observations have been made in regions of volcanic ac- 
 tivity, it has been found that the land is for the most part rising 
 out of the sea, or becoming tilted. The east coast of New Zealand 
 is rising, while its west coast is sinldng. The coast of Naples was 
 sinking for a time, and is now rising. In the great sinking region 
 of atolls in the Pacific Ocean, volcanic aeti'snty seems to be quite 
 extinct. 
 
 MIJfOB VOLCAJ\riC PHEXOMEMA. 
 
 Mud - Volcanoes, Poisoned Caves, etc. — In regions 
 where volcanic activity is nearly extinct, small fissure-eruptions 
 occur, in which the ejected materials may be mud, water, or various 
 gases. Among these last ai"e included strong acid gases, which 
 have a marked effect upon the surface rocks, forming compounds 
 of much commercial value. 
 
 The last stages of dying activity are manifested in the emission 
 of sulphureted hydrogen, the odor of which is peculiarly disagree- 
 able, or carbonic acid, which, being a heavy gas, collects in fissures 
 and craters, and mingles but slowly Avith the surrounding atmos- 
 phere. At the " Grotto del Cane " ijcah'ne) near Naples, its pres- 
 ence is often shown by immersing a dog in the noxious gas. The 
 animal soon falls, and is I'evived by the use of cold water before 
 life is extinct. 
 
 The country about Rome has been the scene of volcanic action, 
 and the springs are copiously charged with carbonic acid' and sul- 
 phureted hydrogen. Lake SoKatara {sol^fah-tah'rah), . between 
 that city and Tivoli, receives a stream of tepid water saturated 
 with carbonic acid, which escapes in such quantities as "to canse the 
 water to look as if it were boiling. 
 
 Tlie stories of the Upas Valley of Java, strewed with the bones 
 of dead animals and birds, are probably based on the presence of 
 carbonic acid in old craters or fissures. 
 
GEYSERS. — EARTHQUAKES AND THEIR CAUSE. 
 
 37 
 
 Geysers. — Water when hot dissolves inauy silieious substances, 
 which are deposited when it cools. A tissure transmitting water 
 thus charged becomes clogged with these deposits, until at last 
 oidy an irregular tube is left. At the surface, tlie ground is cov- 
 ered over many acres with a silieious casing, and divei'sitied with 
 knolls and jjrotuberances of fantastic form and dazzling whiteness. 
 
 If the subterranean temperature be above the boiling-pouit of 
 water, much of this may remain temporarily underground in a 
 superheated condition, ready to burst into steam with the slightest 
 relief of pressure. The rest, reaching the surface, forms streams 
 that gradually cool as they flow away. 
 
 The presence of steam beneath the surface causes these springs 
 to emit their contents explosively like volcanoes. Tliey may be 
 regarded as miniature volcanoes in which lava is replaced by water. 
 The ex]ilauation becomes therefore the same as that aheady given 
 for volcanoes of the Vesuvian type. After an eruption, by which 
 the tube is completely emptied, the water collects in it again and 
 rises to the surface. Beneatli it steam again gathers, raising the tem- 
 perature of the water and becoming itself overheated, until the crit- 
 ical point is reached and a new explosion occurs. Since the supply 
 of heat and the size of the tubes remain nearly constant, the erup- 
 tions follow each other periodically. The name Geyser {gi'ser) (an 
 Icelandic word meaning gusher or rager) has been applied to springs 
 which thus emit their contents explosively and at regular intervals. 
 
 The geysers of Iceland are perhaps the most celebrated, because 
 they were the first studied and have been the longest known. 
 They number about one hundred spouting springs, and lie near 
 Hecla, within a circuit of two miles. The Great Geyser periodi- 
 cally sends up a column of boiling water 100 feet high and nearly 
 10 feet in thickness. Deposits of silica have produced a basin-like 
 momid around the mouth of the tube, so that just before an erup- 
 tion a bowl of hot water 50 feet in diameter is ready for discharge. 
 (On the gaysers of Iceland, see LyelVs ^^ Prbiciples of Geology" 
 vol. ii.,jp. 216.) 
 
 In the volcanic North Island of New Zealand are geysers sur- 
 passing those of Iceland. But the finest geyser region in the world 
 is tiiat of the Firehole River in the Yellowstone Park, Wyoming, 
 where may be seen abundant evidences of volcanic activity in the 
 past, besides mud-volcanoes and holes now emitting steam and 
 other gases continually. The total nimiber of vents of all kinds 
 in this region is estimated at 10,000. 
 
 Questions. — What are the changes produced Ijy contraction of the heated 
 interior of the earth, and where are there illustrations of slowly progress- 
 ing change ? Compare the density of the earth at its center and surface 
 with the density of water. Explain the relation between density and con- 
 traction. "What do deep-sea soundings show to be the condition of the 
 ocean's bottom ? What can you say of subsidence and elevation ? Of 
 underground temperature, and the general condition of the earth's in- 
 terior ? 
 
 Describe the appearance of a volcano. What is a crater, and how is it 
 formed ? How are volcanoes classified ? Describe the succession of 
 events in an ordinary eruption ; the changes due to eruption. Give an 
 account of the eruption of Vesuvius in 1872 ; of Krakatoa in 1883 ; of 
 Etna; of Popocatepetl and Cotopaxi; of the volcanoes of Iceland. State 
 the com])osition of lava. At what period of an eruption is it discharged ? 
 AVliat is ])umice ? Scoria ? Describe the crater of Kilauca, and Hawaiian 
 volcanoes generally. What is known of the geographical distribution of 
 volcanoes, and inferred therefrom ? Present a theory of the cause of vol- 
 canic action. Are adjacent volcanoes generally active at the same time ? 
 Explain the relation between volcanoes and earth-oscillations. 
 
 Describe and account for the phenomena of mud-volcanoes, poisoned caves, 
 and geysers. What is indicated by the issue of carbonic acid from fissures, 
 in volcanic rock i Where are the great geyser regions of the world 'i 
 
 EARTHQUAKES. 
 
 An Earthquake is a commotion transmitted in all directions 
 through the earth's crust in waves of elastic compression. It origi- 
 nates in some center of disturbance, outcrops upon the surface, and 
 is manifested in perceptible motion of the ground. 
 
 Earthquakes vary in intensity from gentle tremblings, requiring 
 delicate instruments for their detection, to convulsions of terrific 
 violence, capable of destroying the most substantial products of 
 human labor. 
 
 Dui'ing the last few yeare tho study of earthquakes ha.s been devel- 
 oped into a special branch of science, to which the name Seismology 
 (from two Greek words meaning science of earthquakes) is given. In- 
 struments called seismometers have been devised for measuring the 
 shocks due to seismic energy. (On seismometers and experiments in 
 observational seismolog3', see " Transactions of the Seismological Soci- 
 ety of Japan" vol. Hi., pp. 1-12; vol. iv.,p. 87.) 
 
 Regions affected. — Earthquakes occur in all parts of the 
 world, but are most frequent in mountainous regions, especially 
 amid mountains that are geologically young, and in regions of vol- 
 canic activity. In some cases the shocks are directly the conse- 
 quence of volcanic eruption, but they occur also in places and 
 under circumstances that indicate no connection with volcanoes. 
 
 The Andes region of South America and the southern part of Italy 
 include some of the most frequently and disastrously shaken districts in 
 the world, as well as some of the most active volcanoes. But earth- 
 quakes often occur without the exhibition of any unusual activity in 
 these volcanoes. The Himalayas and table-lauds of Central Asia are 
 subject to violent earthquakes, but almost free from volcanoes. The 
 Alps and the Pyi'enees are often shaken, but include no volcanoes that 
 are not extinct. The same is true of the American Coast Range south of 
 the Columbia River. Earthquakes occur also, though less frequently, in 
 certain non-volcanic basins, such as the valley of the Mississippi and the 
 basin of the Baltic Sea. They are most rare in Russia. 
 
 Pa.st and Present Frequency of Earthquakes. — Robert Mal- 
 let collected a catalogue of more than six thousand earthquakes occur- 
 ring between 1606 B. C. and 1850 A. D. Since 1850, the number of earth- 
 quakes recorded has greatly increased, though there is no reason to be- 
 lieve that there has been any increase in actual frequency. By the use 
 of appropriate instruments in Italy, Japan, and elsewhere, it has been 
 proved that in such regions as these hardly a day passes without a no- 
 ticeable earth-tremor. Probably not a moment elapses without an earth- 
 quake in some part of the world. 
 
 Cause of Earthqviakes. — No one cause can fully account 
 for all earthquakes. By far tiie most general explanation is to be 
 foimd in the breaking of the earth's crust under the same contrac- 
 tion that squeezes out lava from volcanoes, and folds the regions of 
 weakness into mountain-ranges — the shrinking of the crust on the 
 cooling interior. The strata bend very gradually, and the rock is 
 put into a condition of strain, until it suddenly yields with a vio- 
 lent concussion. One wall of the resulting fissure may slide past 
 the other, producing a fault {seej>. 10), and giving a strong impulse 
 to the adjacent rock. All rock is more or less elastic, and hence 
 the impulse is propagated in every direction as an earth-wave. 
 Most earthquakes are now believed to be the result of such fault- 
 ing, due to sti-ain gradually developed in the slow contraction of 
 the earth's crust. 
 
 The theoi'y that earthquakes are due to subterranean explosions of 
 steam is perhaps applicable to some of the shocks that accompany vol- 
 canic eruptions ; but such shakings are usually only local, and there is 
 no evidence suflicieut to establish this as a cause for the great tremors 
 that have at times been felt over miUions of square miles of the earth's 
 surface. {Consult a lecture by Professor J. S. Newberry, ''School of 
 Mines Quarterly," October, 1S80.) 
 
Questions on the Map of Volcanoes and Seismic 
 Areas. — Trace the longest line of active volcanoes you can find on this 
 map. Where are they most numerous in the neighborhood of the Atlantic 
 Ocean ? Where do you find active volcanoes in Europe ? Do you find 
 extinct volcanoes in Europe? Where? Name all the islands of the mid- 
 Pacific Ocean upon which you find active volcanoes. What remarkable 
 series borders the Indian Ocean ? Point out Krakatoa ; Vesuvius ; Strom- 
 boli ; and Etna. Is the coast-line rising or sinking in the neighborhood of 
 these volcanoes ? Where is sinking land to be found in the neighborhood 
 of volcanoes ? At what places in the United States are the coasts sinking ? 
 
 Where in South America ? Where in North America are the coasts rising? 
 In South America ? What do you observe about Greenland ? Where is 
 the most extensive sinking area in the world ? Estimate the length of this 
 in degrees of longitude. Translate these into miles. Give its width in 
 degrees of latitude. Translate into miles. What sinking tract do you find 
 next in area ? What is the most characteristic feature of these tracts ? 
 Are there any coral regions in the immediate neighborhood of the United 
 States? Where? Point out the most northern coral-reefs in the Atlantic. 
 About what is their latitude and longitude? Do you find any coral-reefs 
 ■ equally remote from the Equator on the south side ? 
 
 
Vj.>t HIO 
 
 111 i.iniiui.h L*'I \\,-.t 
 
 KERM*OEC IS. 
 
 ^CHATHAM I. 
 
 (I l„..L C i'W* 
 
 I ^1 
 
 Satiiii'"^''"^* 
 
 COMPARATIVE HEIGHTS OF VOLCANOES 
 
 
 VOLCANOES OF THE CENTRAL ZONE 
 
 '"'"'' i. 
 
 ■o f .? a -J « 
 
 ^ -^ £; S g^ t . 
 
 Zinc 
 
 A 
 
 m 
 
 r/m/xon. ,.. ■?' **' /, ^ 20,000 fL 
 
 ■* ° *^ / ? 4' "ii'^i? '■■ * 
 
 ,0,000 o J o ^ "0 i" II » * #■ 10,000 
 
 P A C IF I C C E A" If ^ 
 
 WEST INDIES I ICELAND [ 
 
 CENTRAL ASIA 
 
 
 r ISO MATH A if ■) A V A I . 
 
 AFRICA 
 
 VOLCANOES ON THE WEST SIDE OF THE PACIFIC OCEAN 
 
 
 -^^■#~ 
 
 lO.UU 
 Snow Lin 
 
 f^J^?f^..SiUHii 
 
 XA MCH A TKaJkuRILE IS.| J A PA N I S L A H_p S 
 
 PHILIPPINE IS.) MOLUCCAS 18. 
 
 NEW HEBRIDES NEW ZEALAND 
 
 ANTARCTIC CONTINeNT" 
 
 VOLCANOES ON THE EAST SIDE OF THE ?^ PACIFIC OCEAN 
 
 s * 
 
 .*» 
 
 20,000 ft. at- 
 
 J 5 e ..«' 3 ? . 
 
 3 ? i? ;? fli S. 6 
 
 ,, ,S 
 
 0.000. (- , , S "^ ■§ /it 
 
 ALEUTIAN IS. | A L A S K A | UNITED STATE 
 
 ^ iMimhji M 
 
 .^ aj ■» o «j 
 
 -5 ' -a; « 
 
 I c 
 
 mp 
 
 -5 - ■^(^«^-jfl(f'S:??r5„JJ'-f 
 
 M E X I |"CEN. AWERICAT'iaco^. ]ec"u«°ob| P E R U j C' H I L E 
 
 ^m\A^_A:^'l 
 
 30.000 K 
 10.000 
 
 
40 
 
 ANALYSIS OF AN EARTHQUAKE-SHOCK. 
 
 The Violence of an Observed Eartliquake-Sliock 
 
 may depend upon the following conditions : 
 
 1. The degree of strain preceding the concussion. 
 2.' The extent of rock that yields. 
 
 3. The nature of the rock transmitting the impulse. 
 
 4. The distance of the observer from the starting-point. 
 
 The production of earthquakes just hefore a volcanic eruption, or 
 during its continviance, is due probably to the repeated Assuring of the 
 earth below the crater, the concussions resulting from sudden expansion 
 of steam, and the collapse of cavities emptied by the eruption. They 
 often cease after the outflow of lava begins, but as frequently continue for 
 a long time, the equilibrium underground being not established at once. 
 
 Dui-ation of an Earthqnake-Shock. — Although the 
 production of an underground iissure may be sudden, it is never 
 instantaneous. A slight tremor is first felt ; this quickly rises to a 
 maximum, and then dies out more slowly, the entire shock lasting 
 from fifteen seconds to two minutes or more. By the aid of seis- 
 mometers, the duration is found to exceed considerably what is 
 noticeable by the imaided senses. 
 
 Eartliqiiake-Periocls. — An earthquake is usually not lim- 
 ited to a single shock ; several shocks occur in succession. At first 
 these are separated only by a few minutes or houi's, the earHest 
 being most violent ; their intensity then diminishes as the intervals 
 become greater, until after a few months the ground is no longer 
 sensibly disturbed. 
 
 During the twenty-four hours following the destruction of Lima, in 
 October, 1746, 200 shocks were counted ; and within the next four months, 
 850 more were felt. 
 
 At the island of St. Thomas, one of the Lesser Antilles, an earlb- 
 quake occurred in 1868, in which 283 shocks were counted in a little 
 over nine hours. 
 
 In some cases a series of violent shocks occurs, each attended 
 with its retinue of minor ones, forming collectively one great 
 seismic convulsion that may last for weeks. Such catastrophes are 
 most frequent in volcanic districts. 
 
 In the Central American state of Salvador, near Lake Ilopango, 
 more than 600 earthquake-shocks were felt during the last ten days of 
 1879. The water of the lake was thrown into commotion, the ground 
 was broken into a network of cracks, and in January, 1880, a new vol- 
 cano rose in the center of the lake. These earthquakes were obviously 
 products of volcanic energy. 
 
 After the earthquake that shook New Zealand in 1848, the shocks 
 continued for nearly five weeks, and during much of this time at the 
 rate of at least 1,000 shocks a day. 
 
 The city of Messina in Sicily was destroyed in 1783, and the agita- 
 tion of the ground continued with but little intermission for about ten 
 years. 
 
 Nature of Earthquake -Waves. — The nature of these 
 waves is best understood by assuming a single point as the focus 
 of disturbance. From this a wave proceeds out spherically, each 
 ])article traversed by it receiving a forward and then backward 
 motion. If a body be immediately over the focus, it is thrown 
 vertically upward. Elsewhere the motion is both upward and side- 
 ward, the upward coniponent becoming less in comparison with the 
 other as the horizontal distance is increased. 
 
 If the focus be a long fissure instead of a point, the motion be- 
 comes rather more complex. In some cases a whirling eiiect is 
 produced, as in the Calabrian earthquake of 1783, in which blocks 
 of stone forming square columns were twisted at various angles. 
 {See Professor Miltit^s '■'■ Earthqiiahcs and other Earth Move- 
 ments" J3. Jt.1.) 
 
 Illustration of Intensity of Shock. — In 1797 an earth- 
 quake occurred in the Andes, its focus being almost under the 
 town of Eiobamba, in Ecuador. The ground was shattered in 
 some places ; the bodies of men were thrown uj)ward one hundred 
 feet into the air and found afterward on a hill across a river. 
 Graves are said to have been rent open, and corpses hurled out of 
 them. 
 
 Despite such violence, the extent of swing imjjosed upon the 
 ground by an earth-wave is seldom more than a few inches. By 
 the use of seismometers, the vertical component has been found 
 rarely to exceed one-fiftieth of an inch ; and, when the horizontal 
 component exceeds a fom'th of an inch, buildings are shattered. 
 
 Determination of an Earthquake - Focus. — The 
 
 earthquake of 1857 near Naples was carefully studied by Mallet. 
 By examination of the cracks produced in buildings, and of the 
 direction in which bodies were thrown, he estimated the focus to 
 be a fissure nine miles long, the point of greatest commotion being 
 near one end of it and not more than ten miles below tlie siu-face. 
 With the aid of seismometers, the direction of motion and the 
 angle of emergence may be registered at many different places 
 around the same focus. By comj^aring these and noting the time 
 at which tiio shock occurred at the station-point of each seismome- 
 ter, the position of the focus and the rate of transit through the 
 ground may be computed. The depth is rarely more than twenty 
 miles. 
 
 Velocity of Transmission. — Japan is continually shaken 
 by earthquakes, most of which are faint, and seismometers arc 
 kept always in readiness to register the motion. The following 
 results have been deduced from many observations, those of special 
 importance being in connection with the earthquake of October 
 25, 1881 : 
 
 1. Different earthquakes across the same country may travel 
 with different velocities, varying from a few hundred feet to two 
 miles or more a second. 
 
 2. The same earthquake travels more rapidly near its focus than 
 across distant regions. 
 
 3. The greater the intensity of the shock, the greater is the 
 velocity of transmission. 
 
 Earthquakes have been artificially produced by the explosion of 
 gunpowder or dynamite underground. The rate of transit for shocks 
 produced by gunpowder was observed by Mallet to be 825 feet a second 
 in sand, and 1,665 feet in granite. Dynamite explosions are more sud- 
 den and violent than those of gunpowder. An explosion of about 
 50,000 pounds of dynamite was effected at Hallett's Point, near New 
 York, in 1876. Through the neighboring country the rate of transit 
 varied from 5,000 to 8,000 feet a second. About 300,000 pounds of dyna- 
 mite were exploded at Flood Eock in October, 1885. The rate through 
 the same country varied from 5,000 to 20,000 feet a second, being fast- 
 est where the ground is of hard rock and slowest where it is sandy. 
 (/See " Science,'''' January 8, 1886.) 
 
 Effects of Earthquakes on Land. — The effect of an 
 earthquake-shock is usually far more destructive on beds of sand 
 or clay than on sohd rock. In 1755, the most disastrous earthquake 
 on record passed under Lisbon. The lower part of the city, built 
 on clay, was utterly destroyed. All of the buildings in the upper 
 part, resting on a foundation of basaltic rock and hard hmestone, 
 escaped entirely. 
 
 In soft ground, a violent earthquake nearly always produces 
 cracks, which often close just after the passage of the wave, but 
 sometimes are left as open chasms. 
 
EFFECTS OF EARTHQUAKES. 
 
 41 
 
 At the Calabrian earthquake, in 1783, a few such chasms were formed 
 that exceeded 100 feet in width and 200 feet in depth, varying- from half 
 a niiio to a mile in length. In the Port Royal earthquake, 1092, people 
 were swallowed up by fissures or trapped about the middle. At the time 
 of the Mississippi earthquake, 1811, water mixed with sand and mud was 
 thrown out of the fissures iu jets that dashed over the tallest trees. 
 
 Other effects produced by the passage of earthquakes have been 
 disturbances in the level of lakes and rivers, the drying of springs 
 and formation of new ones, the alteration of the temperature of 
 water, the depression or elevation of large tracts, and even horizon- 
 tal movements causing changes in the position of fences and walls. 
 
 The Ischian Earthquake.— The island of Ischia, in the Bay of 
 Naples, was the scene of a destructive earthquake, July 28, 1883, which 
 was presaged not only by premonitory shocks, but by abnormal varia- 
 tions in the temperature of the thermal springs for which the island is 
 noted. A number of towns were destroyed or seriously damaged ; and 
 nearly 2,000 persons lost their lives. This earthquake is believed to have 
 had its origin in a rupture along an old volcanic fissure. {Consult " The 
 American Journal of Science," vol. xxvi., December, 18SJ.) 
 
 Co-SEISMAL AND IsO-SEISMAL LiNES OF THE CHARLESTON EiKTHQrAKE, 
 
 The Charleston Earthquake.— From 50 to 100 earthquakes occur an- 
 nually in the United States, but most of them are mere tremors of the 
 ground and hardly noticeable. The most violent of the present century 
 took place on the 31st of August, 1886, causing great destruction at 
 Ch.arleston, S. C. It was followed by slight shocks occurring at iri-egu- 
 lar intervals through many weeks. The focus was a line of fracture, 
 from which the disturbance extended over most of the country east of 
 the Mississippi River. The position of this line and the rate of progress 
 of the earthquake, as determined by the United States Geological Survey, 
 are shown in the accompanying map, in which the elliptic Co-seismal 
 Lines connect those places that were shaken at the same instant — while 
 the dotted Iso-seismal Lines indicate the sections where the intensity of 
 the shock was equal. {See RockwooiTs ''Notes on American Earth- 
 quakes;" and Prnf. ShaJer's "Aspects of the Earth" 2:12}. S6-4.5.) 
 
 The Eiviera Earthquake. — On the 2od of February, 1887, the north- 
 ern part of Italy was shaken by an earthquake, involving the loss of 
 about 800 lives in the many towns that suffered. The greatest damage 
 was done at the fashionable winter resort of Riviera (re- ce-a'rah). About 
 seven hours after the fu-st shock was felt in Italy, this earthquake was 
 
 detected at Washington by means of a seismometer. The earth-wave 
 therefore crossed the intervening area, 4,000 miles, at the rate of nearly 
 600 miles an hour, or 840 feet a second. 
 
 Effect of Eartliqviakes at Sea. — Many great earthquakes 
 have begun under the sea, near coust-lines. 'I'he effects of these 
 are worst of all, because of the great waves which follow. 
 
 The immediate cause of .such a disturbance may be a submarine 
 volcanic e.\j)Iosion, or probably more often the faidting of the sea- 
 bottom, the focus being close under the water. The sudden uplift 
 of one wall through hundreds of feet would be a sufficient cause 
 for the production of a wave higher than any produced by the most 
 violent stonu. The water, once disturbed, moves up and down 
 many times, each wave spreading out and extending thousands of 
 miles. The destructive effect of such waves on a neighboring shore 
 may even exceed that of the earth-wave. The sea at first recedes, 
 and then sweeps over the exposed ground and far upon the land. 
 The recession has been estimated as much as two or three miles. 
 Ships thus caught are tirst stranded on the mud, and then dashed 
 to pieces or borne inland. 
 
 At Lisbon, in 175.5, 30,000 persons were killed by the earth-shock and 
 falling houses. The first sea-wave, 00 feet high, came an hour after- 
 ward, flooded the wreck made by the earthquake, and 30,000 more per- 
 ished before the series of great waves had spent their energy. 
 
 The velocity of transmission of the sea-wave is much less than that 
 of the earth-wave, and depends upon the depth of water. Those which 
 followed the Lisbon earthquake were distinctly perceptible on the 
 American shores. After the wave has traveled a long distance, the 
 motii^in is comparatively gentle, like that of a tide, recurring at intervals 
 ranging from ten minutes to half an hour. 
 
 Relation of Eartliquake.s to other Phenomena. — 
 
 By conqiarisou of records covering long periods, it has been found 
 that earthquakes are slightly more frequent in winter than in sum- 
 mer, and at times when the relative position of the sun and moon 
 is such as to produce high tides. The earth's cru.=t at certain places 
 may be in a condition of strain, almost at the critical point of rup- 
 ture. A change in the temperature or pressure of the air may 
 possibly increase the surface strain. The attraction of the moon 
 may have a similar effect. But such agencies are far from being 
 alone sufficient causes for tJie production of earthquakes. 
 
 Prediction of Earthquakes. — In volcanic regions, the 
 escape of soluble gases through minute fissures has occasionally 
 served as an indication of underground disturbance by altering the 
 taste of mineral springs ; rumblings in the ground are often 
 heard at the same time. But such signs are very untrastworthy. 
 Accounts, also, of peculiar conditions of the air, or of the human 
 system, or of the tenqjcr displayed by animals, as premonitors of 
 earthquakes, have no better basis than superstition. 
 
 Questions. — -Define seismology. What is meant by an earthquake ? Whore 
 arc cartliquakes most frequent ? Where rare ? Discuss the accepted 
 modern theory of earthquakes. Can they ahvavs be traced to volcanic 
 action ? On what does violence of earthquake-shock depend ? Descriljo 
 an earthquake as regards duration, periods, dynamic effect, nature and 
 velocity of wave-transmission, and in explanation of the different move- 
 ments imparted to the earth's surface. Explain co-seismal and iso-seis- 
 mal Unes; earthquake-foci. 
 
 Under wliat circumstances have earthquakes proved fata! to human life on a 
 large scale ? Describe earthquake-effects, especially in connection with 
 the Lisbon, Ischian, and Charleston calamities. Can you discern the 
 utility of volcanic vents, and suggest how volcanoes may possibly act as 
 great safety-valves for the prevention of more frequent and more disas- 
 trous convulsions than those we are familiar witli ? How valuable are 
 indications of ajjproaching earthquakes ? 
 
THE WATERS OF THE EARTH. 
 
 Water is the principal agent that wears down tlie continents, 
 and iills up the oceaubasins with the fragments of such disintegra- 
 tion. In this process of leveling, it leaves the harder I'idges ex- 
 posed, and carves out the picturesque scenery of mountain-regions. 
 Water is also the most imjjortant highway of communication on 
 the globe, the source of power on which civilization is most de- 
 pendent ; it is, moreover, indispensable to all teri'estrial life. 
 
 The science whose object is the measurement and descrip- 
 tion of the seas, lakes, rivers, and other wajters of the earth, is 
 called Hydrog'raphy (from two Greek words, meaning water- 
 description). 
 
 Composition and Properties of Water. — Water is a 
 chemical combination of two gases, oxygen and hydrogen. It ex- 
 ists ordinarily as a liquid, but may be readily transformed into a 
 solid or a vapor by the withdrawal or apphcation of heat. In its 
 liquid state it fills the oceanic valleys and the beds of streams ; it 
 forms ponds and lakes in the depressions of the land, and collects 
 in the cavities of rocks to produce springs. As a solid, it appears 
 in the glacier and iceberg, and constitutes the frozen covering of 
 the earth's crust toward either pole. In the form of vapor it is 
 universally present in the atmosphere we breathe, and under cer- 
 tain conditions becomes visible as cloud and mist. 
 
 Water, when absolutely still, is an almost perfect non-conductor 
 of heat. The temperature of a mass of it can be changed, there- 
 fore, only by the internal motion of currents. In coohng, it con- 
 tracts until the temperature 39'2° F. is reached, when it begins 
 slowly to expand. Its density, therefore, is greatest at this tem- 
 perature, and the liquid thus cooled at the surface sinks to the bot- 
 tom, to be replaced by the warmer portions from below. When 
 the surface-water is cooled to 32° F., it crystallizes into ice, ex- 
 panding at the same time aboait one-tenth. Ice, therefore, always 
 floats, and because of its poor conductive power it protects the 
 water beneath from further reduction of temperature. A sh;.llow 
 body of water in continued extreme weather may become frozen 
 to the bottom, but this is not known to have ever occurred where 
 the depth exceeded a few feet. 
 
 The expansion of water in cooling from 39'2° to 32° is "sup- 
 posed to be due to the beginning and progress of crystallization, 
 which is completed with sudden increase of expansion at 32°. 
 
 By heating water under ordinary conditions, it expands slowly 
 until a temperature of 212° F. is reached, when it begins to change 
 into steam. Additional heat accelerates this change without raising 
 the temperature. 
 
 Three Tempei'atures are thus important to remember: 
 32° F., the freezing-point of water, or melting-point of ice ; 39'2° 
 F., the point of maximum density for water; 212° F., the boiling- 
 point of water, or condensing-point of steam. 
 
 The boiling-point of water is subject to variations dependent chiefly 
 upon the pressure of the atmosphere. On high mountains, where the 
 air is less dense than at sea-level, the boiling-point is lower. 
 
 An exposed body of water gives off vapor from its surface at all 
 temperatures. The rate of loss by evaporation is fastest when the air is 
 dry, warm, and kept in motion by the wind. The vapor, as it ascends, 
 forms clouds (seep. 7S). 
 
 To change the temperature of a pound of water through 1° F., re- 
 quires more heat than to effect an equal change of temperature in any 
 other common substance. Water is hence less rapidly wai-med and 
 cooled than land. Since the air takes its temperature from bodies with 
 which it is in contact, the presence of a large mass of water tends to keep 
 thc> au' from becoming either very cold or ver}' warm. 
 
 Water has the capacity for dissolving a greater variety of substances 
 than any other one liquid. This property causes it to be an important 
 agent in changing the character of all soil with which it comes in con- 
 tact. {Consult Professor Charles F. Chandler's lecture on icater, de- 
 livered before the American Institute of the City of New York.) 
 
 IJfLAJ^D WATERS. 
 
 Disposal of Rainfall. — Of all the water that falls as rain 
 
 or snow, it is estimated that about one-third sinks into the ground, 
 another third flows off at the sm-face and is carried to the sea, and 
 the remaining third is evaporated. This ratio is variable, depend- 
 ing to some extent on latitude, climate, and nature of ground. 
 Ultimately nearly all finds its way to the sea, to be again evap- 
 orated and to take part ceaselessly in the great circulation of 
 Nature. 
 
 Percolation of Water tliroiigli the Gronnd. — Any 
 
 piece of rock, apparently dry when taken from the ground, will 
 lose in weight if exposed to heat. It contains water distributed 
 through its mass in minute fissures and cavities. But independ- 
 ently of this, water passes througii soils of all degrees of hardness, 
 percolating fastest through sand, very slowly through clay, and 
 almost wholly stopped by solid granite or limestone. Strata of 
 sandy soil are therefore permeahle {a:!iniiting of heing passed 
 through) ; those of clay and granite, comparatively im^ermeahle. 
 
 Surface-Springs. — When a permeable stratum («, see fig- 
 ure) rests upon one that is impermeable (6), the rain soaks through 
 and the lower layers become saturated. Underground channels are 
 formed by which the water j-eaches the surface, ca^ising a Spring 
 
 at the point (s) 
 where the line 
 between the two 
 strata is exposed. 
 Such springs are 
 often found on 
 hill-sides. If the 
 area be large and the slope of the harder strattim slight, a spring 
 thus formed may continue active from year to year without inter- 
 mission, and serve as the unfailing source of a brook. 
 
 Artesian Wells. — If the permeable stratum rests between 
 two impermeable strata, as in the figure on the following page, 
 and is inclined so tnat an edge {e) is exposed, the region of satura- 
 tion may extend to great depths. If a bore-hole (A) be drilled 
 through the overlying strata (c) so as to tap the saturated region 
 (a), the water reaches the surface, being forced up by the press- 
 ure below. The force depends on the elevation of the edge (e) 
 where the water began to percolate, however distant it may be. 
 An artificial spring thus made is called an Artesian Well. 
 
 Artesian wells derive their name from the French province of Artois 
 (in Latin artesiwn), where the first European wells of this kind are 
 believed to have been sunk. But the boring of artesian wells in the 
 Desert of Sahara appears to have been an ancient practice ; in all desert 
 plains resting upon porous strata through which the surface-water per- 
 colates and is lost, their value is inestimable. Within the last quartei"- 
 century, numberless perforations have been made by French engineers 
 in the Sahara, with the effect of supplying the needed water for irriga- 
 tion, and thus converting much territory that was deemed irreclaimable 
 
 FOUMATIOX OF A SdRFACE-SpRING. 
 
MINERAL AND INTERMITTENT SPRINGS. 
 
 43 
 
 into fertile and habitable country. Among the most noted artesian 
 wells are those at Louisville, Ky. (i.OSC! feeti, and Charleston, S. C. (1,250 
 feet) ; the latter discharges 1,200 gallons of water an hour. 
 
 lu the western part of Pennsylvania mineral oil called petroleum 
 is found in groat quantities under the ground, and over 30,000,000 bar- 
 rels are annually brought to the surface by means of artesian wells. 
 
 Mineral Springs. — If a porous stratum beariug 
 water is interrupted by a " fault " (/), the effect is simi- 
 lar to that of a boring. The water is forced up through 
 crevices, and appears at various points on the surface 
 along the line of fissure. Having soaked through many 
 miles, or even hundreds of miles, of earth in its under- 
 ground passage, it often contains various salts and gases 
 in solution. If tlie depth from which it issues be great, ^ ^ 
 
 ths water may be quite warm. 
 
 Among the most celebrated mineral springs in the United 
 States are those of Saratoga, whose water is strongly charged ^^ V 
 with carbonic acid and salts. The springs are found along / i 
 
 a line of fissm-e which passes through the village. They ^"^ i 
 differ in their medicinal properties. (Consult Dr. Walton s ^ 
 
 "Mineral Waters of the United States and Canada."') -^ 
 
 The hot springs of Arkansas are more than a hundred 
 in number, and are similarly found along a line of fissure. 
 The temperature varies from 135° F. to 160° F., and on ac- 
 count of the medicinal properties of the water these springs 
 are sought for the treatment of disease. A cold spring is 
 found within a few feet of one of these hot springs, the dif- 
 ference in temperature between the two being nearly 100° F. They issue 
 from separate fissures, one of which is in connection with a subterranean 
 arsa of heat, and the other is not. 
 
 Virginia is noted for its mineral springs, hot and cold, sulphui'ous and 
 aluminous, chalybeate {impregnated with iron) and alkaline. Among 
 those most widely resorted to are the Hot, Warm, and Healing Springs 
 of Bath County. West Vu-ginia also contains valuable sulphur springs. 
 
 Among the medicinal springs of Eui-ope are especially to be noted 
 those of Vichy in France, Baden-Baden in Germany, and Carlsbad in Bo- 
 hemia, whose waters are r?garded as speeifics for certain forms of disease. 
 
 to A L, when it stops. The crevice acts merely as an imperfect 
 siphon. Tlie cavity, then, through drainage from the surface, 
 slowly fills again to the higher level, to be once more emptied. 
 Such intermittent spriiigs as tiiese are rare in comparison with 
 those whose periodic flow depends upon variation in rainfall. 
 
 
 " "-l. -i r" -^ »A^ f'Z.;- <^f 
 
 •'\JPl*8- 
 
 Ct ' 
 
 i 
 
 a , 
 
 ■Vrtesia.n Well and Mineeal Spring. 
 
 Interinittent Springs. — Where the drainage area is small, 
 or the strata are highly inclined, springs often appear after a 
 shower of rain, and run dry within a short time. In some cases, 
 especially where limestone abounds, underground cavities become 
 reservoirs of water. 
 
 If a crevice from one of these happens to extend as shown in 
 the figure, the exit being lower than the point {A) where the 
 crevice communicates with the cavity, hut another point (Z?) being 
 higher, the water will rise to the level B L before beginning to 
 flow. It continues to drain the cavity until the level is reduced 
 
 -/i.^^^^^^. 
 
 •"<*/ ; 
 
 An Ls'teumittent .Spring, with Section of the same. 
 
 The rock beneath the surface, even when not of limestone, always 
 contains cavities which serve as reservoirs of water. Below a certain 
 level, which varies with the nature of the strata and the distance from 
 the sea, the ground is in a permanent state of saturation. This level 
 varies still further with the seasons, being higher after periods of rain- 
 fall. To obtain water in any place, it is necessary only to dig until tliLs 
 limit is passed. Water oozes into the cavity, and a Well is thus pro- 
 duced. (On the origin of springs, artesian wells, mineral and thennal 
 waters, consult LyelVs " Priiiciples of Geology, '" vol. i., p. 386.) 
 
 RIVERS. 
 
 Origin. — The brooks that trickle from sj^rings down the 
 slopes of mountains combine to form rivulets, which, swollen by 
 tributaries, in turn unite, and a river results. The warmth of the 
 Sim causes pei-ennial streams to flow from snow-fields and glaciers, 
 and these, thei'efore, act like springs as the sources of rivers. 
 Some rivers, like the St. Lawrence, are the outlets of lakes. 
 
 River-Drainage. — The region which is drained by a river 
 is called its Basin. A water-shed is the ridge that separates two 
 river-basins. The great water-sheds of a continent are its chief 
 mountain-chains, which determine the position and size bf its prin- 
 cipal rivers. Their slopes becoming worn away by erosion, minor 
 basins and water-sheds are produced. 
 
 Velocity. — The steeper the slope down which it flows, the 
 greater is the velocity of a river. But water can not glide over the 
 soil without being retarded; hence the velocity of a river is af- 
 fected by the character of its bed, the nature of its course, whether 
 winding or straight, the ratio of its width to its depth, and the 
 volume of water carried. 
 
 A slope of three inches in a mile produces a current of between two 
 and three miles an hour, about as fast a.s ordinary walking. A slope of 
 three feet in a mUe makes navigation laborious. 
 
 The size of a river depends upon the area drained and the an- 
 nual rainfall It varies with the seasons and the climate. 
 
u 
 
 RIVERS AND WATERFALLS. 
 
 Transporting Power of Rivers. — Rivers, when moving 
 slowly, wear awa_y their banks, and cai-rj along in a state of suspen- 
 sion the earthy particles thus dislodged from the soil. These re- 
 main suspended until the onward flow is slackened, when they are 
 deposited in the shape of mud or line earth called s/'lt. Thus are 
 formed shallows, sand-bauks, and bars. 
 
 If the velocity of the current be increased, its carrying power is 
 increased also, but in a higher ratio. A current flowing at the rate 
 of a foot a second is capable of carrying particles of gravel ; if this 
 rate be doubled, it will transport fragments sixty-four times as large. 
 
 A mountain-stream flowing rapidly soon bears away all the soft ma- 
 terial in its path, cutting for itself a deep and rocky bed. It dexsosits the 
 i-oavser parts of its biu'den as soon as its velocity is checked ; hence the 
 upper portion of its bed is strewed 
 with pebbles and even bowlders. 
 Many such streams unite to form 
 a river, whicb thus carries silt from 
 the mountains to the sea. 
 
 The finest silt is deposited very 
 slowly. The turbid waters of the 
 Amazon discolor the ocean 300 
 miles from land. 
 
 A river's bed is continually 
 deepened in its upper part by 
 looS of material, and made broad- 
 er and shallower in its lower 
 part by successive deposits. The 
 velocity of the water passing 
 through it is greatest in the 
 middle, and least at the mar- 
 gins; therefore, in overflowing 
 its banks at times of freshet, a 
 river also renders them higher 
 by deposit. 
 
 Kapids and Waterfalls. 
 
 — It has already been shown 
 that rivers play an imjDortant 
 part as agents of erosion, there 
 being hardly any limit to their 
 excavating power. Work of this 
 kind in active progi-ess is well 
 illustrated in waterfalls. When 
 the course of a river is aci'oss 
 the outcropping edges of strata 
 differing in hardness, the softer 
 earth is worn away more rap- 
 idly until the harder ledge pro- 
 jects ; over this, the river leaps 
 as a Catai'act. Unequal erosion 
 
 may merely increase the slope of a river-bed, causing the stream to 
 flow with heightened velocity over the inequalities of its channel ; 
 thus Rapids result. 
 
 There is no cataract in the known world equal in grandeur to that 
 of Niagara. The Niagara River above the Falls is divided by Goat 
 Island into two channels, through which the water flows to the edge of 
 a stratum of hard limestone underlaid by soft shale. The level of Lake 
 Erie is 334 feet above that of Lake Ontario. The limestone plateau on 
 which it rests outcrops as a very thin layer at Lewiston on the border of 
 Lake Ontario, and thickens as Lake Erie is approached. This layer has 
 been cut through and washed away, so that a deep gorge seven miles 
 long remains as evidence of the water's worlc. As the shale is displaced, 
 fragments of limestone are detached, so that since 1875 the edge over 
 
 The Skj^eggedalfos, Norway. 
 
 which the largest mass of water plunges to form the Horseshoe Fall 
 has been receding at the rate of nearly 25 feet annually. Tlie average 
 rate of recession for all parts of the cataract, as it cxiots at the present 
 time, is estimated to be 2.4 feet a year. 
 
 About two miles below the Falls, the slope is suc'a as to cause the 
 waters to rush tumultuously over fragments of rock left in former 
 years, forming the famous Whu-lpool Rapids. Shells, similar to those 
 now found in Lake Erie, have been met with in the strata near the top 
 of this gorge, on both sides, showing that the level of the water must 
 have been at that height in geologically recent times. {See " Pictur- 
 esque America,^'' vol. i.,.p. 432.) 
 
 Among other pictm-esque American Cataracts may be mentioned 
 the Falls of the Yosemite in California, produced by the plunge of the 
 Merced River over several precipices ui succession in a total descent of 
 2,600 feet, one of the falls being 1,600 feet high; the Falls of the Yellow- 
 stone in the National Park, and 
 those of the Lewis River, one of 
 the afiiuents of the Columbia; the 
 Falls of St. Anthony, near the junc- 
 tion of the Minnesota and the Mis- 
 sissippi, which have cut a gorge 
 eight miles long to Fort Snelling; 
 Trenton Falls, a superb chasm near 
 Utica, New York; and the Toccoa 
 and Tallulah Falls in Georgia. 
 
 In Europe, the Falls of tlic 
 Kliine at ScliafFhausen, on the bor- 
 der between Germany and Switzer- 
 land, where the river plunges from 
 a height of 80 feet, afford a grand 
 illustration of the erosive power 
 of water, especially in the cutting 
 away of two pillar-shaped lime- 
 stone rocks which stand in the cur- 
 rent. The gorge of the Rhiix, ex- 
 tending from Bingen to Roland- 
 seek, a distance of sixty miles, is 
 believed to have been cut by an 
 ancient waterfall. 
 
 The Alps abound in cascades of 
 no great volume but of consider- 
 able height, due to streams from the 
 Alpme snow-fields. Among these 
 may be mentioned the Staubbacb 
 (stoU'b'bahJc — dust-stream), which 
 leaps from a height of 900 feet into 
 the Lauterbrunnen Valley (low'- 
 ter-hroon-nen — nothing but fount- 
 ains) near Interlaken, and is dis- 
 pei-sed by the wind in the form of 
 spray before reaching the bottom. 
 A singularly beautiful sheet of wa- 
 tery particles hangs like a silver 
 veil over the crags, oscillating in 
 the wind, and varying in tint ac- 
 cording to the position ;Df the sim. 
 The famous Pyrenean Cascade 
 of Gavar'nie, in southern France, 1,300 feet in height, presents a simi- 
 lar effect to the Staubbach fall. It is situated amid exti'emely romantic 
 scenery, whose glaciers and waterfalls attract numbers of tourists. 
 
 Norway abounds in cataracts i-emarkable for their height, volume of 
 water, and great beauty. One of the finest of these, the Slfjaeggedalfos 
 (sheg-ge-darfos—fall in a bearded, i. e., heavily wooded, glen), lien at 
 the head of Hardanger Fjord, surrounded by the grandest of glaciers and 
 water-courses. This magnificent fall, having a total descent of 1,400 
 feet, has been pronounced as worthy of a visit as Niagara itself. 
 
 The most imposing of South American cataracts, and among the 
 grandest on the globe, is the Fall of Tequendama {ta-ken-dah'mah), 
 near Bogota, whose waters plunge through a gap but 36 feet wide, and 
 are precipitated 650 feet in an unbroken mass amid the tropical vegeta- 
 tion and gorgeous scenerv of the Andes. 
 
DELTAS AND BARS. 
 
 45 
 
 233 f 
 
 In Asia .'Uid Afrioii aro iiiitnrrons waterfalls of consklorablo volume. 
 Victoria Falls, in llie Zambezi River, were discovered by Livingstone 
 in IS.")."). The water leaps into a chasm 400 feet deep, bounded by per- 
 pendicular walls of basalt, breaking as it falls into a white mass resem- 
 bling a sheet of driven snow, and sending up columns of vapor to a 
 height of SOO feet above the brink of the cataract. The volume of water 
 is second only to that of Niagara. (On earth-sculjiture by waterfalls, 
 cunsiilf Phillips's "Manual of GeoloQij" Part I., p. I'lJ, ) 
 
 Deltas. — If a river empties into a large bo'lv of quiet water, 
 deposits of silt and sand are ceaselessly accunmluted at its mouth, 
 tending to obstrtict its free passage outward. Overflowing its 
 banks, it in time makes many new mouths. The group of outlets 
 with their intervening silt-banks is called a delta, because shaped 
 like tlic Greek letter delta (A), with the apex pointing up the river 
 and the base fronting the sea. A delta thus consists of successive 
 layers of alluvial deposit, penetrated by constantly shifting chan- 
 nels. Deltas grow fi'om year to year until they may extend many 
 miles into the sea. 
 
 Tlie Po has carried down deposits which thus extend for 21 miles, 
 their progi-ess during the last century having been at the rate of 300 feet 
 a year. On the accumulations of this river, 566 feet in thickness, stands 
 the modern city of Venice. Sections of artesian wells at this city display 
 to advantage the structiu-e of a delta and the range of its beds. The 
 
 variability of the 
 strata shown in 
 the cut is ex- 
 plained by the ir- 
 regularity of sea- 
 sons and the ac- 
 tion of floods and 
 currents. The 
 city of P.avenna, 
 originally situat- 
 ed like Venice in 
 a lagoon, is now 
 four miles from 
 the sea. {See 
 PrestwicWs " Ge- 
 ology,'''' vol. i., 
 p. S5.) 
 
 In the delta 
 of the Nile stands a statue of Rameses II., the base of who^e pedestal is 
 at present 9V feet below the surf, ace. It was erected about 3,200 years 
 ago. Borings have been made in the middle of the delta to the depth 
 of 75 feet without penetrating through the alluvial soil. Egypt is ele- 
 vating by such deposits at the rate of six inches in a century. 
 
 Many Euro])ean rivers furnish instructive examples of delta- 
 growth. The Tiber is advancing its coast-line at the rate of about 
 12 feet ])er .innum, so that Rome's ancient harbor, Ostia, is now 3 
 miles iidand. Along the shores of the North Sea, the wide plain 
 of the Netherlands has been formed by the delta-deposits of the 
 Rhine, Meuse, Scheldt, and other rivers. The Rhotie delta is 
 rajiidly advancing in the ilediterranean, and that of the Danube 
 in the Black Sea. 
 
 The deltas of the Ganges and JJrahinupiitra Rivers together 
 form a mass of mud that covers about 15,000 square miles, an area 
 larger than that of the whole of Massaciiusetts, Rhode Island, and 
 Ooimecticut. Its front is 200 miles broad, and its starting-point is 
 now 220 miles inland. An artesian well at Calcutta was bored to the 
 depth of -iSO feet without reaching the bottom of this delta deposit. 
 
 The Mississippi delta is advancing into the Gulf of Mexico at 
 the rate of 338 feet annually. The area covered by it is about 
 12,300 square miles, and at New Orleans it is known to be more 
 than 630 feet thick. The present river winds through its own 
 
 566jt 
 
 Sectio.\ of the Delta Deposits of Venice, with overflow- 
 ing Artesian Wells (after Laurent). 
 
 deposits from its junction with tlie Ohio to tlie Gulf. In the lower 
 part, its bed has become so raised that lev'ees {elevated banks or 
 causeways) are necessary to protect the neighboring country from 
 inundation. The ainnial discharge of seiliinent by the Mississijipi 
 is estimated at nearly seven and one-half billion cubic feet. 
 
 The Lena River of eastern 
 Siberia, flowing in a cliannel six 
 miles wide eight hunJieJ miles in- 
 land, and draining an area of ei^ht 
 hundred thousand square miles, 
 discharges into the Arctic Ocean 
 a vast volume of water through 
 numerous mouths wliich form a 
 characteristic delta represented in 
 the scconipanving map. {Refer to 
 Melvi/lc's "hi the Lena Delia" 
 pp. SOS, 373.) 
 
 Bars. — When a river Hows into an ocean whose shores arc 
 swept by tides, the formation of a delta is checked by the alternate 
 reversals of the current each day. The tide rises and falls, causing 
 the water to flow inward and then outward. The lower part of the 
 river is widened by successive erosion in opposite directions. 
 When the outflowing water meets the sea, a deposit of mud is 
 formed called a Bar. This is cut by one or more channels where 
 the water forces its way through to the sea. Another bar is formed 
 where the incoming tide is checked by water flowing down from 
 the sources of the river. This is called the head of tide-water. 
 
 The Hudson affords an excellent example of the effect of tides. In 
 its lower course, its width varies from one to three miles. A bar extends 
 from Coney Island across to Sandy Hook, and is pierced by three chan- 
 nels, through which ships are piloted. The river is obstructed by .shoals 
 at the head of tide-water near Troy. 
 
 Questions. — What can you say of the properties and composition of water ? 
 Name the subjects of hydrography. Define springs, and show how they 
 may be classified. Account for intermittent springs. Describe the nature 
 and origin of artesian wells, illustrating by a diagram. What are thermal 
 springs ? Is there any relation between such and volcanoes ? What min- 
 erals and gases occur in the water of springs ? Describe some celebrated 
 medicinal springs. 
 
 What is the origin and history of rivers ? the basin, or drainage-area, of a 
 river ? a water-shed ? On what does the amount of water in a river-basin 
 depend ? Explain by diagram the details of a river-course from source to 
 mouth. How far do rivers cut their own channels ? 
 
 Name the chief waterfalls of Europe. Describe the following cataracts, and 
 give the depth of leap in each instance r Niagara, Victoria, Yoscmite, 
 Skjsggedalfos, and Falls of the Rhine. What is a river delta ? How do 
 deltas grow ? Describe some noted deltas ; the formation of bars. Can 
 you state the importance of rivers in reference to the occupation of the 
 earth's surface by man 3 
 
4-6 
 
 LAKES, THEIR GEOLOGICAL HISTORY AND FUNCTIONS. 
 
 LAKES. 
 
 .Origin of LalieSo — Bodies of water oecnpymg depressions, 
 or hollows, in the land are known as Lakes ; when small, they are 
 called Ponds. As a rule, the great lakes of the world owe their 
 origin to the upheaval of the ocean-floor, and not, as in the case of 
 excavated valleys and canojis, to the erosive action of running 
 water. The Caspian Sea, still having a maximum depth of 3,G00 
 feet, has thus been severed from the main ocean ; and there is geo- 
 logical evidence that a great inland estuary, in past ages, separated 
 Europe and Asia, and extended across the steppes to the Arctic 
 itself. The elevation of the English Channel 3(J0 feet would con- 
 vert a large, portion of its bed into diy land, and leave a number of 
 small lakes occupying its deeper portions. (On the origin of lakes 
 in upheaval, consult PhUU^^s's ^^Manual of Geology^'' Part I., 
 
 p. m.) 
 
 Lakes also result fi'om the accnmulation of water in natural 
 hollows produced by the folding of the I'ocks, being fed by springs, 
 or streams that drain the neighboring country. They ai-e some- 
 times vii'tually expansions of rivers. 
 
 The head of a lake is that portion which receives the main en- 
 tering stream, or inlet; i\\e foot, or lower end, that whence the 
 overflow is discharged through the outlet. 
 
 Classification and Distribution. — Lakes may be classi- 
 fied as salt and fresh. Those that have outlets ai'e generally reser- 
 voirs of fresh water; such as have no outlets are mostly salt. 
 When the amount of water supplied by inlets or rainfall exactly 
 balances that lost l)y evaporation and discharge through outlets, 
 the level of the lake remains unchanged. 
 
 Lakes occur in great numbers in the northern parts of both 
 hemispheres, and less frequently, though often of large size, 
 toward the Equator. Salt lakes are met with in the great inland 
 plains in the heai't of continents, where there is no opportunity for 
 their waters to escape. In volcanic regions, lakes not nnfrequently 
 occupy the sites of extinct craters ; such lakes usually have neither 
 inlets nor outlets. 
 
 Size and Depth. — The size and depth of a lake depend 
 upon the surface conditions of the country in which it is formed. 
 In mountainous regions, lakes often fill up the valleys to a certain 
 height ; they are narrow and deep, and but rarely of great length. 
 
 If the lake-basin be in a flat country, its depth is small in com- 
 parison with its length and breadth. Lake Erie covers 10,800 
 square miles of surface, while its depth rarely exceeds 120 feet. 
 
 Lakes as Keservoirs and Pui'ifiers. — Lakes, especially 
 amid mountains, serve not only as reservoirs for the multitude of 
 rills that flow down the mountain-sides, but as regions of deposit 
 for the sediment they bring with them. The swift and muddy 
 streams have their velocity checked on emptying into a lai'ger body 
 of almost quiet water. Deltas are formed, and the water issues 
 perfectly clear at the outlet, thence to continue its career of ero- 
 sion and silt-making in its course to the sea. In proportion to their 
 size, lakes change their level but slowly, and thus tend to give 
 steadiness to the outflow of the regions drained into them. 
 
 The Lake of G-eueva is an expansion of the river Ehone, which 
 enters its east end as a turbid stream whose waters are heavily charged 
 with sediment from the Alps. It lias filled this end of the lake, making 
 a delta nine miles long and fi'om one to two miles wide, that has grown 
 more than a mile since the time of the Romans. The clear blue tint as 
 the water sweeps thi'ough Geneva at the outlet is in striking contrast 
 to its gray color near the delta. 
 
 Professor Geikie defines the geological functions of lakes as 
 follows : I. They arrest and equalize the drainage by regulating 
 the outflow and lessening the destructive eflrects of floods. II. 
 They filter river-water, and permit of the accumulation of new 
 deposits. III. They furnish an abode for certain animal and 
 vegetable forms, and entomb in the growing deposits the remains 
 of plants and animals washed down from the surrounding country, 
 thus preserving a record of the life of the period. 
 
 Salt Lakes sometimes owe their origin to the evaporation of 
 fresh water received through their feeders. The soluble material 
 taken from the surroimding country gradually collected in their 
 basins, and their waters beca:ne charged with various salts, espe- 
 cially those of soda, magnesia, and lime. There being no outlets, 
 and consequently no escape for the dissolved saline matters, these 
 bodies of water, which were originally fresh, became gradually 
 more and more salt. 
 
 The most remarkable example of this variety of lake is the Dead 
 Sea iu Palestine. Its depth is over 1,.300 feet ; its surface is 1,272 feet 
 below the Mediterranean ; hence its bottom is nearly 2,600 feet below 
 sea-level. It is fed by the river Jordan, a fresh-water stream ; but 
 the water of the lake is charged with common salt, nearly ten times 
 as strongly as ocean-water. It occupies the lowest part of a deep 
 valley, where the sun's heat causes evaporation to be in excess of what 
 the lake gains from its affluents. Along the shore at its south end 
 is a miniature mountain-range of solid rock-salt, a ridge six miles long, 
 more than half a mile wide, and over five hundred feet in height. Much 
 of this is covered with earthy deposits of varying thiclcness. The shores 
 are everywhere incrusted, and the water is much more brhiy than at the 
 north end, where the Jordan enters. This salt mountain has been evi- 
 dently deposited from the water of the lake. {Consult article in ''Scien- 
 tific American " for September, 1886 ; and Lieutenant LyncKs '■'Nar- 
 rative of the U. S. Expedition to the Jordan and the Dead Sea.") 
 
 In the neighborhood of the Caspian Sea are several salt lakes, annu- 
 ally diminishing in size, some of which become quite dry in summer, 
 leaving the ground white with salt. Among those is the basin of Lake 
 Elton, from which 2,000,000 pounds of salt are said to be taken each 
 year. 
 
 Lakes that were originally parts of the ocean are not necessarily 
 salt. When, for any reason, more fresh water is received by such 
 a lake than it loses through evaporation, its salt water is diluted 
 and overflows, little by little the salt is removed, and a fresh-water 
 lake in time results. A former connection with the sea is claimed 
 for Lake Baikal (bi'hahX), a vast body of fresh water in Siberia, 
 the volume of whose waters nearly equals that of Lake Superior. 
 {J. Y. Buchanan, '-'■ Encyclojyadia Britannica^^ vol. xiv.,]). 217.) 
 
 Lakes of North America. — North America has the largest 
 lakes in the world. In the Dominion of Canada ai'e the Great 
 Bear, Great Slave, and Athabasca Lakes, which are drained into 
 the Arctic Ocean. The waters of Lakes Winnipeg and Manitoba 
 find their way into Hudson Eay. Lakes Superior, Michigan, 
 Huron, Erie, and Ontario, form a connected group whose outlet is 
 the St. Lawrence River ; their combined area, including the 
 estuary of the St. Lawrence, is 15n,000 square miles. Lake Su- 
 perior is the largest sheet of fresh water known, its area being 
 32,0!i0 square miles, and its average depth about 900 feet. 
 
 Near the Pacific coast there is a series of smaller lakes, scattered 
 over California, Nevada, and Oregon. One of these is in the heart 
 of the Cascade Range in Oregon, at an elevation of 6,000 feet above 
 the sea. Occupying an extinct crater of the same kind as that of 
 Kilauea, but larger, being over seven miles long and five wide, it 
 is called Crater Lake. Around this oval body of intensely blue 
 water, the walls rise in precipices from 900 to 2,200 feet high. A 
 
THE LAKES OF EUROPE, ASIA, AND AFRICA. 
 
 47 
 
 cinder-cone lifts its head 000 feet nut of the water, and two otlier 
 snhniei-ged cones have l>cen found by mounding. Crater Lake is 
 Ijclieved to be the deepest body of water in America, its greatest 
 depth being 2,005 feet. {Consult ''/Science," Auyust '27, 1SS(J.) 
 
 Lake Talme, occupying an elevated valley of tlie Sierra Nevada 
 Range, is environed by inagniticent scenery, and famed for tlie ex- 
 quisite azure tint of its water. 
 
 In I 'tall is the Great Salt Lake, about 200 miles in circumfer- 
 ence and from 12 to CO feet in depth, with no visible outlet. Its 
 waters are heavily diarged with salt; l)ut, unlike the Dead Sea, not 
 to such an extent as to be incompatible with animal life. Connect- 
 ed with Great Salt Lake by the Jordan Eiver is Utah Lake, a sheet 
 of pure fresh water alxmnding in fisli. Tlie waters of many smaller 
 lakes in this basin -region are strongly impregnated with soda. 
 
 Lakes of South America.— There are but two large lakes 
 in South America, viz.. Lake Titicaca, situated in an Andean valley, 
 more than two miles above the sea, on the boundary between Peru 
 and Bolivia, covering an area of 4,<i00 square miles, interesting on 
 account of its ruins and historical associations; and Lake Mara- 
 caybo, 137 miles in length, whose watere are fresh, although it is 
 in communication with the sea. 
 
 Lakes of Europe. — In the northern part of Europe are a 
 numl)er of lakes tril)utary to the Baltic Sea, the largest of which 
 arc the great Russian lakes of Lad'oga and One'ga, prolongations 
 of tlie Gulf of Finland, the remains of a channel rendered dry in 
 part by change in level. 
 
 In the Alpine region are many lakes, some of small size but great 
 depth. The Lake of Lucerne, or " the Lake of the Four Forest 
 Cantons," 25 miles in length and cruciform in shape, situated at 
 the junction of four deep vaUeys which are filled by the streams 
 from the neiglihoring mountains to the level of the outlet, is univer- 
 sally admitted to be the grandest sheet of water in Switzerland. 
 The city of Lucerne (the Shilling One) stands 1,420 feet above the 
 level of the sea, at the point where the emerald-green waters of 
 the Renss {mice) issue from the lake, with Mount Pila'tus tower- 
 ing behind it, and the Rigi {re'ge) in front across the " Forest Sea." 
 
 The charms of the Lake of Lucerne can not well be exaggerated. 
 At every tiirn of the steamer which plies ui)on its waters in summer, a 
 new scene unfolds itself to 
 the tourist. On this side, 
 the mountains descend 
 in gentle slopes, covered 
 with luxuriant verdure ; 
 on that, in precipitous and 
 barren steeps, their sum- 
 mits ci'owned with per- 
 petual snow. Now vel- 
 vety fields approach the 
 shore ; anon, a broad bay 
 s;veeps between peace- 
 ful orchards and brilliant 
 uioadows to the base of 
 (Ustant hills — suddenly, 
 the lake narrows till it 
 seems, as if to advance, 
 the steamer must enter 
 some mysterious tunnel 
 through the granite piles 
 that shut her in. Fluffy 
 rlouds float lialf - way 
 down the momitains, up 
 whose sides black forests 
 creep, growing less and 
 
 The Lake 
 
 less dense as they ascend till a few straggling firs alone battle success- 
 fully with the snows and rea<'li the tops of the less elevated ridges. 
 Here the Spaidsh chestnut, the fig, and the almond, flourish in the open 
 air ; there, sheer walls of rock refuse support to the tiniest shrub. In 
 front, a romantic hamlet mirrors its picturesque chateaux and little 
 church in the glassy waters ; behind, a group of farm-houses clusters on 
 an impending clitt', and daring hay-makei-s gather in their crop from 
 dizzy slopes ; while yonder, a ruin, perched on some frowning promon- 
 tory, or half concealed in the dark foliage, breathes its legend. 
 
 The Lake of Constance, traversed by the Rhine; and the 
 crescent-shaped Lake of Geneva, or Lake Le'man, with its pecul- 
 iar sapphire-blue waters — are justly celebrated for their pleasing 
 scenery. 
 
 The lakes of northern Italy are among the most picturesque 
 sheets on the globe, especially Co'ino with its delightful climate, 
 and Maggiore {mah'l-jo'ratj) with its imposing forest-clad mount- 
 ains. In Sweden and Finland beautiful lakes abound ; while the 
 Scottish lochs ai-e world-renowned for their wild aspects and hLs- 
 torical associations. 
 
 Lakes of Asia.— Probably the deepest body of fresh water 
 in the world is Lake Baikal, the Holy Sea, situated just north of 
 the Altai Mountains in Siberia. Its area is over 9,000 square 
 miles; its depth, more than two miles, or six times that of Crater 
 Lake in America. Thermal and mineral springs are found near 
 its shores, and naphtha floats on its surface. Volcanic phenomena 
 and earthquakes are not uncommon in the surrounding region. 
 
 Koko-Nor (blue sea), south of the Desert of Gobi, has an ele- 
 vation of 10,500 feet. Its waters are salt, and it is without an 
 outlet. 
 
 But Asia is remarkable more especially for its salt lakes, some 
 of which are large enough to be ranked as inland seas. The Cas- 
 pian covers more than four times as much area as Lake Su])erior. 
 The surface of its salt water is 84 feet below sea-level. The Sea 
 of Aral is a diminishing body of salt water, about as large as Lake 
 Michigan, and at the same level as the Caspian. The Dead Sea 
 has been already described. (On the Caspian Sea and the surround- 
 ing territory, consult ^ Donovan^ s " The Merv Oasis," j). 40.) 
 
 African Lakes. — Vast lakes form a prominent feature in 
 the hydrog'raphy of Africa, the principal lake-region lying on, 
 
 and immediately south 
 of, the Equator. Here, 
 at altitudes varying from 
 2,300 to 4,000* feet, are 
 those expanses of fresh 
 water which feed the 
 great rivers Nile and 
 Kongo. Lake Albert 
 (2,300 feet above the sea) 
 and Victoria Nyanza 
 (3,800 feet), connected 
 by a stream broken into 
 rapids, form, together 
 with Lake Albert Ed- 
 ward (3.200 feet), the 
 source of the White 
 Nile. Lake Tanganyika 
 {tahn-gahn-ye'i-a\ over 
 300 miles in length, dis- 
 charges its surplus wa- 
 ters tlu-ough the Xongo 
 
4:8 
 
 DRAINAGE OF NORTU AND SOUTH AMERICA. 
 
 into the Atlantic; wliile Nyassa (ne-a/ig'sa), 300 miles to the 
 sotitheast, occupying 9,000 square miles of the basin of the Zam- 
 bezij drains into the Indian Ocean. (Oa Lake Tanganyika, see 
 Thomsonh " To the Central African Lakes,^^ vol. ii., x?. 1.) 
 
 The lakes that lie in the interior areas of continental drain- 
 age are frequently salt — though Tchad (chahd) in the Soudan is a 
 large fresh-water sea, comparativel}' shallow 
 and having ordinarily no outlet ; and Ngami 
 {n''gah'me). north of the Kalihari Desert, 
 brackish during the diy season, becomes 
 fresh in times of inundation. 
 
 Australian Lakes. — Australia is not 
 supplied with lakes comparable in size to 
 those already described. Shallow bodies of 
 water, both salt and fresh, are numerous. 
 These are subject to extreme changes of level, 
 being high in winter and often drying up 
 and disappearing entirely in summer. 
 
 The accompanying diagram 
 shows the relative heights of 
 some of the well-known lakes 
 of the world. Lake Titicaca is 
 the most elevated lake of con- 
 siderable size, and the Dead Sea 
 is the most depressed, the dif- 
 ference of level between the 
 two being nearly three miles. 
 In the table below will be 
 found further interesting sta- 
 tistics. 
 
 s 
 
 13,000 
 
 11,000 
 
 9,000 
 
 r,ooo 
 
 5,000 
 
 3,000 
 
 1,000 
 
 1,000 
 
 TABLE OF SIZE, DEPTH, ELEVATION, AND TEMPERATURE 
 
 OF LAKES. 
 
 NAME OF LAKE. 
 
 Superior . . . 
 Michigan ... 
 
 Huron 
 
 Erie 
 
 Ontario 
 
 Tahoe 
 
 Great Salt . . 
 
 Titicaca 
 
 Koko-Nor . . . 
 
 Baikal 
 
 Balkash 
 
 Caspian Sja . 
 Dead Sea.. . , 
 Tanganjilta. . 
 
 Como 
 
 Genera 
 
 Constance. . . 
 
 Lomond 
 
 Katrine 
 
 Length 
 in miles. 
 
 Greatest 
 breiidth, 
 in miles. 
 
 Greatest 
 depth, 
 in feet. 
 
 HEIGHT IN FEET 
 ABOVE THE SEA. 
 
 
 
 
 
 
 Surface. 
 
 Bottom. 
 
 350 
 
 100 
 
 1,010 
 
 635 
 
 -375 
 
 320 
 
 80 
 
 864 
 
 57S 
 
 -286 
 
 2S0 
 
 105 
 
 705 
 
 578 
 
 -127 
 
 220 
 
 48 
 
 324 
 
 505 
 
 + 241 
 
 190 
 
 55 
 
 738 
 
 231 
 
 -507 
 
 20 
 
 12 
 
 1,645 
 
 6,250 
 
 -1-4,605 
 
 90 
 
 35 
 
 60 
 
 4,200 
 
 + 4,140 
 
 90 
 
 30 
 
 924 
 
 12,900 
 
 + 11,976 
 
 91 
 
 42 
 
 
 10,600 
 
 
 330 
 
 40 
 
 12;356 
 
 1,360 
 
 -10,996 
 
 340 
 
 55 
 
 238 
 
 72 
 
 — 166 
 
 600 
 
 60 
 
 3,600 
 
 -S4 
 
 -3,684 
 
 45 
 
 10 
 
 1,308 
 
 -1,272 
 
 -2,580 
 
 330 
 
 40 
 
 1,000 
 
 2,700 
 
 + 1,700 
 
 48 
 
 2-5 
 
 1,926 
 
 670 
 
 -1,256 
 
 45 
 
 8-7 
 
 1,017 
 
 1,218 
 
 + 201 
 
 35 
 
 8 
 
 394 
 
 1,283 
 
 + 889 
 
 20 
 
 4 
 
 630 
 
 25 
 
 -605 
 
 7 
 
 0-8 
 
 480 
 
 364 
 
 -116 
 
 Bottom tem- 
 perature. 
 
 38-8° F. 
 
 39-2 
 
 54-6 
 
 44-6 
 
 41-7 to 43-5 
 
 39-6 
 41-4 to 42 
 
 41-4 
 
 Questions. — Define and classify lakes. How have they been formed ? How 
 are they supplied ? Explain their connection with the water circulation, 
 and their geological functions. Give examples of lakes formerly parts of 
 the ocean. "Why are such lakes not necessarily salt ? 
 
 Where is the most extensive lake-region of the globe ? What can you say of 
 the great lakes of North America ? Of South American lakes ? Give an 
 account of the lakes of Europe. Describe the Lake of Lucerne ; the Cas- 
 pian and Dead Seas; Lake Baikal; the lakes of the Nile Basin. Mention, 
 the peculiarities of Lake Tchad ; of the Australian lakes. 
 
 COJ^TIJ^EMTAL DRAINAGE. 
 
 The direction and size of the rivers which drain a continent are 
 determined by the position of its chief mountain-ranges. Most of 
 the water finds its way at last to the ocean, but there are limited 
 areas where the drainage is entirely into salt lakes. 
 
 Drainage of North America. — The chief water-sheds of 
 North America are : 
 
 I. The Rocky Mountain Plateau, traversing the greatest length 
 of the continent, and separating the tributaries of the Pacific Ocean 
 from those of the Atlantic and Arctic Oceans. 
 
 II. The Appalachian Highlands, extending from the Gulf of 
 St. Lawrence nearly to the Gulf of Mexico, and dividing the rivers 
 of the Atlantic slope from those of the Mississippi Valley. 
 
 III. The Height of Land, stretching southwestward from Lab- 
 rador to Minnesota, and separating the Mississippi Valley from the 
 great Northern Low Plain. 
 
 From the Rocky Mountain Plateau, the drainage on the Pacific 
 slope is less than on the side opposite, partly because of the smaller 
 area, but also because, over much of it, the rainfall is slight and 
 evaporation is rapid on account of the elevation of the surface 
 and great dryness of the air. The only rivers of considerable size 
 are tlie Yukon, flowing into Bering Sea, the Columbia, and the 
 Colorado. 
 
 The Mississippi River is the chief outlet for the iuterior slopes of 
 each of the three water-sheds. Its source, Itasca Lake in Minnesota 
 (1,575 feet above the sea), is near the western extremity of the Height of 
 -Land, on its southern slope. From the great western water-shed it re- 
 ceives its largest tributary, the Missouri, besides many that are smaller, 
 such as the Arkansas and Red Rivers. On the east, its main afSuent is 
 the Ohio, which drains most of the western Appalachian slope. The 
 Rio Grande is the most important of the other rivers which drain the 
 eastern slope of the Rocky Mountains. 
 
 South of the Height of Land, and partly surrounded by 
 it, lie the Great Lakes, with the St. Lawrence River as their 
 outlet. 
 
 East of the Appalachian Highlands, the Atlantic slope being 
 narrow, the rivers are all comparatively small. The most impor- 
 tant is the Hudson. 
 
 From the northwest slope of the Height of Land, and the 
 northeast slope of the Rocky Mountain Plateau, a number of 
 streams flow into LIudson Bay, the largest being the Nelson 
 and the Albany River. Finally, the Mackenzie River carries 
 the drainage of the more northern part of the continent into the 
 Arctic Ocean. 
 
 Drainage of South America. — On account of the prox- 
 imity of the Andes range to the Pacific, no large streams drain 
 into that ocean. Three vast river-systems, however, are tributary 
 to the Atlantic. The largest of these is the Amazon System, wliich 
 drains a basin twice the size of the valley of the Mississippi, and 
 equal to two-thirds of the area of all Europe (2,500,000 square 
 miles), the most extensive and most abundantly watered in the 
 world — with feeders, themselves rivere of the first magnitude, that 
 reach into every country on the continent e.xcept Chile and Pata- 
 gonia. The volume of water transported by this system is incon- 
 ceivable. The delta is 200 miles wide, and the depth of the river 
 in places exceeds 300 feet ; with its source in the Andes only 60 
 miles from the Pacific, it gains in its long course of 4,000 miles 
 an impetus which carries its fresh waters 200 miles unmixed into 
 the sea. 
 
DRAINAGE or EDRASIA, AFRICA, AND AUSTRALIA. 
 
 49 
 
 iS'orth of the Silvas of the Amazo!i, between tlie plateau of 
 (Jniuiia and the nortlieastern spurs of tlie Andes, is a basin drained 
 by the Orinoco, .jTu.UUU square miles in area. On the table-land of 
 the Parinae {pah-re' may) Chain, which divides the drainage area 
 of this river from that of the Amai;on, occurs one of the most re- 
 markaljle bifurcaticjus iu the world. While the main stream of 
 the Oi-iuoco flows on toward the northeast, a branch, the Cassi- 
 quiare ijcahs-fc-hc-ali' raij\ turns southward, and after a rajiid course 
 of ISO miles unites with the liio Negro, so that during the annual 
 floods a portiou of the waters of the Orinoco is discharged iuto the 
 Atlantic through the Amazon system. 
 
 Between the Brazilian Plateau aud the Andes lies the low plain 
 drained by the Paraguay and Parana Rivers. The Uruguay unites with 
 the Parana at its mouth, aud the resulting great estuary is called the Rio 
 de la Plata. The Parana rises iu a swampy region that is connected 
 with the head-waters of the Madeira. There is heuce no complete sepa- 
 ration between the Amazon aud either of the other river-systems of 
 South America. 
 
 Other rivers of minor importance in South America are the San 
 Francisco, di-aining part of the Brazilian plateau ; the Magdaleua, be- 
 tween two spurs of the Andes ; aud the Colorado and Negro of the south, 
 di'aining portions of the Argentine Republic. 
 
 Drainage of Eurasia. — The soutliem part of Eurasia is 
 mostly highland, the great plateau widening in the ca.st and extend- 
 ing northward as far as Bering Strait. AVhere it is broadest, there 
 is little raiirfall. The greatest rivers, therefore, are in the vast 
 Siberian and Russian plains, and in the limited plains near the 
 Indian and Pacific Oceans, where deficiency in area is more than 
 counterbalanced by the conditions producing enormous rainfall. 
 
 From the northern slopes of the Alpine Highlands, the Loire, Seine, 
 Rhine, Elbe, and Vistula, flow into Atlantic waters. The Scandinavian 
 Peninsula is too narrow to produce any except insignificant streams. 
 Southward, a few small rivei-s flow into the Mediterranean Sea, such as 
 the Ebro, Rhone, and Po ; and the Black Sea receives the Danube, the 
 lai'gest river that has its origin iu the Alps. 
 
 Into the Ai'ctic Ocean di-ain the Dwina aud Pelchora, the Obi, Yeni- 
 sei, and Lena, with a few other rivers of smaller size ; into the Pacific, 
 the Amoor (ah-moor'), Hoang Ho, Yangtze Kiang, and Mekong. 
 
 To the immense rainfall on the southern slopes of the Hima- 
 layas are due the Indus, tlie Ganges, and the Brahmaputra, which 
 are the chief rivers of southern Asia. The Indus, taking its rise 
 IS, 0(10 feet above the sea, breaks through the barriers of the Hima- 
 layas, receives the united streams of the Punjab (Jive great waters), 
 and reaches its delta after a course of 2,000 miles. The Brahma- 
 putra rises far up on the plateau of Thibet, and in part of its course 
 over the highlauds it is not far distant from the Yangtze Kiang, 
 which drains a considerable part of the "great Chinese plateau be- 
 fore reaching the low plains. The Euphrates and the Tigris are 
 outlets for the least sterile part of western Asia between the pla- 
 teaus of Araljia and Persia. 
 
 A considerable area within Eurasia is depressed so as to be deprived 
 of connection by water with any of the oceans, the Caspian and Aral 
 Seas serving as interior reservoirs. The former receives the Volga, the 
 largest river in Em-ope, and the Ural, which is the arbitraiy division- 
 Ime between Europe and Asia. The O.xus and Syr Dai'ia (seer dar'yah) 
 drain the western slopes of the Altai Range iuto the Sea of Aral. Its 
 eastern slopes feed the Tarim (tah-reem') River which finds a small res- 
 ervoir in the shallow, salt Lop Nor, a lake without outlet in the desert 
 regions of Tus-kcstan. Altogether, this is the largest region of interior 
 drainage in the world. 
 
 The Drainage of Africa. — The seaward margin of the 
 great African plateau is skirted with mountain-chains, which con- 
 stitute the axes of the continent. Its great rivers, therefore, neces- 
 
 sarily have their source in the interior, either in the lake-region, or 
 on the inward slopes of these coast-ranges, through which tliey 
 force a passage to the sea. By far the greater portion of the 
 oceanic drainage is to the Atlantic, directly or through the Medi- 
 terranean Sea. The Nile, the Niger, the Kongo, and the Orange, 
 are thus discharged. The Zambezi aud the Limpopo enter the 
 Indian Ocean. 
 
 The Nile rises in the equatorial lake-region ; it is 3.700 miles 
 long, aud drains a basin of 1,GOO,0()0 s<piare miles. Its delta occu- 
 pies an area of 9,000 square miles, and is subject to an auuual over- 
 flow which leaves behind a stratum of rich deposits. 
 
 Through upper Egypt, deep, broad valleys have been excavated iu the 
 rich soil by the tributaries of the NUe, swollen by the gi-eat rainfall 
 among the mountains of Abyssinia. The former contents of these enor- 
 mous cuttmgs have been distributed over the lowlands at times of iimn- 
 dation. The Atbara and the Blue Nile are the mud-camers. The White 
 Nile conveys, suspended iu the finest particles, vegetable matters from 
 the lakes whence it flows. (On the fertiUzing rivers of Egypt, consult 
 Dr. ^Villiams's ^^ Life in the Soudan," jy. 3S.) 
 
 The Kongo (length, 2,800 miles) rivals the Mississippi in mag- 
 nitude, discharging, after the season of tro]iical rains, a volume 
 of water nearly equal to that of the Amazon. It drains a basin 
 1.200,(100 miles in extent, and abounds in lakes and water-cour.ses. 
 The river terminates iu an estuary. The Niger ranks third in 
 volume of water and area of basin. Its delta is more extensive 
 than that of the Nile by 5,000 square miles, the marginal branches 
 being 200 miles aiiart. The Zambezi enters the ocean by numerous 
 mouths. Prodigious quantities of sand are annually carried down 
 by its current into the sea; the finer particles are caught by the 
 returning tides, and have been deposited, by successive ebbs and 
 flows, with masses of decaying vegetable matter, through ages, 
 until a delta extending a hundred miles inland has resulted. 
 
 Tlie Drainage of Australia. — The peculiar positions aud 
 courses of the rivers of Australia render probable the supposition 
 that at a comparatively recent geological period the interior of this 
 continent was an ocean-bed, the ranges parallel to its eastern aud 
 western coasts being the Idghlands of former island groups. The 
 MuiTay and its tributaries flow into the interior from the eastern 
 mountains, and finally merge in a shallow lalce with an outlet to 
 the ocean on the south. (Jther rivers spend their waters in inland 
 swamps and lakes, becoming reduced to insignificant streams dur- 
 ing the dry season. (On the rise aud fall of Australian rivers and 
 the lakes of the desert - region, consult Wa7'burtoiCs '■'■Jourudj 
 across the Wist Interior of Axistralki^^ pp. 205, 2So.) 
 
 The distribution of the earth's g^eat river-systems, as described iu 
 the foregoing paragrajjlis, makes plain the relation of di'ainage to a con- 
 tinent's water-shcvls. The total area drained to the Atlantic Ocean, di- 
 rectly or through its anus, the Gulf of Mexico, the Mediterranean aud 
 Baltic Seas, etc., nearly ecpials 10,000,000 square miles. The Paeitic (in- 
 cluding the Indian) and the Arctic Ocean I'eceive, each, the drainage of 
 over 5,000,000 square miles. 
 
 Questions. — Wliat is a drainage-area ? Explain the relation between conti- 
 nental a.xcs and drainage ; tlie connection of lakes with water circulation. 
 Specify the principal water-sheds and river-systems of Korth America. 
 Describe the Amazon System. Give an outUne of the drainage-areas con- 
 nected with the Mediterranean Sea ; the Gulf of Mexico ; the Sea of Aral. 
 Describe the drainage-system of the Nile ; state the nature and extent of 
 the Nile delta, and the economic results of the annual overflow. 
 
 Trace the course and history of the following rivers, mentioning details of 
 basin, tributaries, countries traversed, particulars concerning lakes, rapids, 
 waterfalls, and bifurcations or connecting canals : St. Lawrence, Missouri, 
 Blississippi, Yukon ; Orinoeo and .Vnuizon ; Ganges and Indus ; Kongo and 
 Zambezi; Volga and Lena; Murray. 
 
T^MINATION 
 LAND 
 
 1 \indicatt^!t TTami Cui^rents. 
 
 i indicates Cold Currents. 
 ' ' — indicates direction of Currents. 
 
 • — *- indicates direction of Currents from April to Octoter, 
 
 • — indicates direction of Currents from Octolier to Aiiril. 
 
 Note: The land uncolored has no river drainage to the ocei in. 
 
 WILKES 
 
 L A (V^T^-^iidT::::^- Easi 
 
 GRAH 
 LA 
 
 GreenwicTi 
 
 Questions on the Map of Continental Drainage and Ocean- 
 Currents. — What ocean receives the waters of the Great Slave Lake ? the waters of 
 Lake Superior ? of Lake Baikal ? of Lake Ladoga ? of Lake Tanganyika ? of Victoria 
 Nyanza ? Into what ocean does the Euphrates River flow ? the Lena ? the Colorado ? 
 the Mississippi? the Ganges? the Darling? Are there any large rivers in South Amer- 
 ica which flow into the Pacific ? Why ? (Consult Physiographic Map, pp. 20 and 21.) 
 Are there any on the Mexican and Central American western coasts ? Why ? 
 
 What part of North America has no drainage-outlet ? What is the largest body 
 ot water in this region ? Where can regions without drainage-outlets be found in 
 
 South America ? in Africa ? in Australia ? in Eurasia ? What is the largest resei 
 of interior drainage in the world ? Is its surface above or below sea-level ? (Sec 
 20, 21, and 47.) What is the largest interior reservoir in South America ? Wb 
 its elevation ? (See pp. 20, 21, and 48.) What other interior reservoirs are the: 
 Eurasia? Which is the loftiest of these? (See pp. 20 and 21.) Which the low 
 What is the level of its surface? (See p. 46.) Making allowance for the projectio 
 the Map (Mercator's, see p. 9), state which of the oceans drains the largest land-sur: 
 Wiat is the average direction of the Atlantic North Equatorial current ? of 
 South Equatorial ? of the Guinea current ? of the Equatorial counter-current of 
 
'? Trace the Gulf Stream and its branches. Trace tlie .laijan current. Do you 
 IT cold current near Labrador ? What is its soutliern limit ? Trace tlie southern 
 )f tl(jating icebergs in the Atlantic. Can you account for its irregularity ? Do 
 111 su'h a limit in the North Pacific? Explain. (See p. .53.) Trac the north- 
 nit of floating icebergs from Antarctic regions. Can you account for its irregu- 
 (Comiiare with Map, pp. 20 and 21.) What peculiarity do you notice about the 
 ar c\irrcnt ? Explain. (See pp. 61 and Vl.) Trace the .\pnlhas current. What 
 it to turn near the Cape of Good Hope ? Give the direction of the Humboldt 
 t. The South Atlantic current. Are these currents warm or cold ? Compare 
 
 the direction of currents on the east and west coasts of Australia. By comparison with 
 the Physiographic Map, can you offer any probable explanation of the remarkable course 
 of the South Australian current? By comparison with the Isothermal Map (pp. 6H and 
 67), can you sec any relation between the ocean-currents and the difference of climate 
 between the east and west coasts of South America ? of Africa ? Are there any consider 
 able currents connecting the Pacific and Indian Oceans? If any, where are they and in 
 what direction ? What is the prevailing direction of current along the coast of Guinea ? 
 How do you account for this ? Do you find any current in the Gulf of Mexico ? fCom- 
 pare with p. 53.) Trace the direction of currents in the neighborhood of Cuba, 
 
52 
 
 PEOPEETIES OF SEA-WATER. — LI FE IN THE OCEAN. 
 
 OCEAJ^- WATERS. 
 
 Area and Volume. — The ocean is a continuous body of 
 salt water, covering nearly tliree-fou.rtlis of the earth's surface, and 
 in volume twenty or thirty times as great as the sum of all the 
 land-masses above its level. 
 
 For convenience, the ocean is arbitrarily divided into five parts, 
 which are separately called the Atlantic, the Pacific, the Indian, 
 the Arctic, and the Antarctic Ocean. 
 
 Color of the Ocean. — The color of the ocean, when viewed 
 in mass, is so deeply blue that a special name, ultrcmiarine, has 
 been given to its characteristic tint. A glass of sea-water is clear 
 and coloi-less, more so, indeed, than most spring-water. But it 
 powerfully absorbs certain rays of light, so that what comes from 
 beneath the surface at considerable depths appears tinted in con- 
 sequence of loss by selective absorption and I'eflection. 
 
 White light is a mixture of many tints. If these be separated, as in 
 passing rays through a prism, the most prominent are red, yellow, green, 
 and blue. At the surface of the sea all the tints are reflected, but with 
 increasing depth the red and yellow become absorbed, then the green, 
 and finally all. The absorption is not noticeable for a thickness of a 
 few iucbes ; at five or six feet the loss of red causes the rest of the light 
 to appear greenish ; then this deepens into blue and violet. Six hun- 
 dred feet down, all perceptible light is absorbed. For human eyes, 
 Uierefore, all would be impeneti-able darkness at this depth. 
 
 Composition of Sea-Water. — The sea may be regarded 
 as an inexhaustible mineral spring. Sea-water has a disagreeable 
 taste on account of the several salts which it holds in solution. 
 Common salt (chloride of sodium) is the most abundant. Sulphate 
 of magnesia (Epsom salt) gives it bitterness. Sulphate and carbon- 
 ate of lime are always present, with small quantities of salts of 
 potassium, iodine, and other elements. Thirty poimds of sea- 
 water contain about one pound of salts. 
 
 The saltness of the ocean is not uniform. Near the Equator, the loss 
 of pure water by evaporation causes the surface-water of the sea to be 
 slightly more briny than in temperate zones. The same is true of cer- 
 tain landlocked seas, like the Mediterranean, Red Sea, and Persian Gulf. 
 The Black Sea, the Baltic, and the polar oceans, are slightly freshened 
 by the inflow of water from the land. 
 
 Variations in Appearance of the Sea.— The sea as- 
 sumes a dark lead-color when the sky is overcast, because much 
 light is absorbed by the clouds before reaching its surface. Where 
 the water is shallow, the sediment I'eflects light of its own tint and 
 modifies that of the water. The China Sea is colored yellow by 
 mud diffused through it from the Hoang Ho. The dark-brown 
 mud of the Amazon gives a deep coffee-color to the sea near its 
 mouth. The Red Sea takes its name from the tint imparted to its 
 waters by myriads of minute marine plants. 
 
 Pliosi>horescence. — Sea-water, especially in the tropics, 
 teems with minute animals that shine like the glow-worm and fire- 
 fly, particularly when they are momentarily brought into contact 
 with the air. The jjroperty of phosphorescence belongs to many 
 creatures, chiefly those of low type. Fi-om some of them, light is 
 emitted not only during life, but after death. Very little is known 
 as to the cause of this phosphorescence, or the manner in which it 
 is utilized and controlled by its possessors. 
 
 It is on the crests of waves, or where the water is churned into foam 
 in the wake of a ship, that these animalcules swarm, and at night the sea 
 appears to glow with flying sparks. " Fantastic forms are seen, luminous 
 circles, starry plumes, or lambent fringes ; while a mass of these creatures 
 resembles a globe of red-hot metal fiiuging off green festoons." 
 
 Density and Pressure of Sea- Water. — The density of 
 sea-water exceeds that of fresh water in proportion to the amount 
 of salt dissolved. If we suppose a given mass of pure water to 
 weigh 1,000 grains, the same volume of average sea-water will 
 weigh about 1,027 grains. The ratio of the second of these 
 weights to the first, 1.027, is called the specific gravity of sea-water, 
 and is a measure of its density. It varies with the saltness, the 
 temperature, and the depth. 
 
 The greater density of sea-water increases its buoyant force and its 
 pressure upon bodies immersed in it. Such bodies, if suijk to a depth 
 of thirty-three feet, are pressed on all sides with an mcrease of fifteen 
 pounds on each square inch. At a depth of three miles, the increase is 
 about three and a half tons per squai-e inch. This is sufficient to crush 
 any ordinary hollow body, like a closed tube or bottle. No creature 
 accustomed to life in the ah, or at the surface of the water, could with- 
 stand such crushing force. 
 
 Life at the Bottom of the Sea. — Some animals are 
 naturally adapted to conditions of life that would be fatal to 
 others. Certain kinds of fish have been ascertained to live at a 
 depth of 16,500 feet, a little over three miles. Deep-sea fishes are 
 generally black or silvery in color. At great depths, blind fishes 
 occur, possessing mere rudimentary eyes, and without special organs 
 of touch. 
 
 The sea-bottom at great depths is covered over large areas with 
 the shells of minute creatures, to which the name forarainifera 
 has been given. {See page 100,) 
 
 It seems probable that life exists at all depths in the ocean, but the 
 distribution of it is quite irregular. There are large tracts in the various 
 zones where material dredged from the bottom has been found to be 
 always devoid of living creatures. At slight depths, animal life is met 
 with in almost unliuiited variety, and sea-weed in some places covers 
 the surface. (On deep-sea fauna, consult Professor Wyville Thomsmi's 
 " The Depths of the Sea," p. 407.) 
 
 Effect of Cold on Sea- Water. — Sea- 
 water grows denser wlieu cooled ; but, unlike 
 fi'esh water, its point of maximum density is ' 
 lower, not higher, than its freezing-point. For 
 that of the Atlantic (of 1.027 specific gravity), 
 the maximum density is at a temperature of 
 25.4°, its freezing-point at 27.4°. In the act of t 
 freezing, there is a tendency toward separation 1 
 of the substances held in solution, so that sea-ice i ' 
 is far less salt than sea-water. ^ 
 
 Temperature of the Sea. — At the 
 
 Equator, the surface temperature of the open 
 sea is about 80°. In confined bodies of sea-wa- 
 ter like the Red Sea or Persian Gulf, where the 
 direct effect of a tropical sun is heightened by 
 warm air from the adjacent deserts, the surface 
 temperature in summer may rise to 90° or more. 
 It diminishes generally with increase of latitude, 
 until in the Arctic regions in winter it is reduced 
 as low as 28°. 
 
 It is only at the surface that such a wide 
 range of temperature is encountered. By sink- 
 ing a thermometer in the sea, the temperature in 
 most latitudes is found to diminish rapidly, until Decrease ofTempera- 
 35° or 36° is reached. In equatorial regions this ^"'^ ^"™ ^'^'^""'^ 
 
 OF Depth 
 
 limit is generally at a depth of 10,000 or 12,000 ,„ , , ' 
 
 . ° . ■' -', . ' , ' (Banda Sea, between 
 
 feet ; it nses nearer to the surface as the poles Borneo and New 
 
 are approached. In Arctic regions the surface- Guinea.) 
 
 39'A' 
 
DEEP-SEA TEMPER.VTURES. — THE ATLANTIC AM) THE PACIFIC. 
 
 53 
 
 water is colder tlian that below, so that the thermometer rises at 
 iiicreased depths. At all depths below the limit of 35°, the tein- 
 ])erature is nearly constant ; this, therefore, may bo iu>siiiiied as tiie 
 average temperature of the ocean. 
 
 The rate of chunjje of temperature with latitude and depth is well 
 shown in the aocouipauying table, each of the four columns representing 
 
 a separate set of sound- 
 ings. It will be seen, 
 from columns I. and II., 
 that the lowering of tem- 
 perature is greater in 
 the firet 3,000 feet than 
 in the next 11,000 feet. 
 By a comparison of col- 
 umns III. and IV., it 
 will be observed that 
 with increasing depth 
 there is cooling in the 
 one case and warming 
 in the other. {Con- 
 sult article o»i " The 
 Properties and Consti- 
 tution of Sea-Water,^'' 
 in ^^ Popular Science 
 Monthly,'' March, 1885.) 
 
 Coiiflguration of the Sea-Bottom.— Since 1870 several 
 cruises have been made for the purpose of studying the temperature, 
 depths, and currents of the ocean. Great improvements have been 
 achieved in the methods of deejvsea soimding, in dredging, and in 
 the use of the thermometer. The sea-bottom is now known to be 
 diversified with basins and plateaus. The slopes, however, are very 
 gentle, so that, if the water were removed, all would appear to the 
 eye like a flat plain, except in the immediate neighborhood of a con- 
 tinent or island, where a slope of as much as 5° is occasionally found. 
 
 The bottom is usually line sediment of clay, sand, or chalky 
 material ; rarely pebbly or rocky. The mud, when examined with 
 the microscof)e, is often found to contain multitudes of shells of 
 foraminifera. Over large areas, the 
 sea-bottom is thickly strewed with 
 volcanic dust and small fragments 
 of lava. {Consult article entitled 
 ^'Deep-Sea Soundiny" hy Captain 
 George E. Bdlcnap, U. S. N., in 
 Ilarnerslei/s '■'■Naval Eneycloprndia.") 
 
 Depth in 
 feet. 
 
 I. 
 
 .Si (logrecH 
 south of 
 Equator. 
 
 n. 
 
 •2a liegrees 
 north of 
 Equator. 
 
 III. 
 
 5.5 degrees 
 north of 
 Equator. 
 
 IV. 
 
 "8 degrees 
 
 north of 
 
 Equator. 
 
 () 
 
 78° 
 
 73.4° 
 
 57.2° 
 
 32° 
 
 120 
 
 
 
 03.6 
 
 
 270 
 
 68 
 
 
 
 
 310 
 
 
 
 
 
 33.5 
 
 1,500... 
 1,800... 
 
 
 51. S 
 
 48.2 
 
 
 1,920... 
 
 41 
 
 
 
 
 4,566... 
 
 
 
 
 33.5 
 
 4,650... 
 
 .... 
 
 
 41 
 
 
 5,400... 
 
 
 39.2 
 
 39.2 
 
 
 8,400. . . 
 
 
 
 37.4 
 
 
 13,200.. 
 
 33 
 
 
 
 
 15,760.. 
 
 
 35.3 
 
 
 
 The three important branches of the Atlantic Ocean are the 
 Mediterranean Sea, the (inlf of Mexico, and Hudson Bay. 
 
 The Mediterranean Sea has several basins, the deepest of which 
 lies between Sicily and Greece. At its greatest depth, two and a 
 half miles, its waters are warmer by 20° than those of the Atlantic 
 at the same depth. At the bottom of the Strait of Gibraltar, one- 
 fourth of a mile below the surface, both bodies have the same 
 temperature, 55°. The cool strata at greater dej)tlis in the Atlantic 
 can not rise above the barrier at Gibraltar, and therefore no water 
 colder than 55° can enter the Mediterranean. 
 
 The Gulf of Mexico is a basin with three depressions more than two 
 miles deep. Between Yucatan and Cuba, the depth is a little over a mile; 
 and between Cuba and Florida, hardly more than half a mile. At its 
 greatest depths, the water is warmer than in the ocean at the .same distance 
 below the sm-face. Indeed, this fact is always observable in the case of 
 detached basins separated by submarine barriers from the deep sea. 
 
 The Caribbean Sea, although apparently not so distinct from the 
 ocean, is really made up of two deep basins, nearly separated from the 
 Atlantic by a volcanic mountain-range, whose exi)osed portions consti- 
 tute the West Inthan Islands. It attains a depth of three and a half 
 miles south of Cuba. This part Ls called Bartlett Deep, and is divided 
 from the main ba.sin by an offshoot of the submarLue mountains extend- 
 ing southwest from San Domingo. The West Indian Islands are sejja- 
 rated from one another by valleys, no one of which much exceeds a mile 
 in depth. (Consult paper hy Captain J. R. Bartlett, in "Journal of 
 the American Geographical Society," vol. xiii., 1881.) 
 
 The Pacific Ocean.— The Pacific is by far the largest of 
 the oceans, its area being about twice that of the Atlantic. Its 
 connection with the Arctic at Bering Strait is shallow. It rapidly 
 widens toward the south, until between California and China the 
 distance across is fully 8,000 miles. From the Indian Ocean, the 
 Pacific is separated by an immense archipelago, between the 
 islands of which its waters are shallow, or gathered into detached 
 basins such as the Sulu, Celebes, and Banda Seas. The island- 
 barriers are continued southward in New Guinea, Australia, and 
 New Zealand, so that no deep current can pass from the Pacilic to 
 
 The Atlantic Ocean.— The 
 
 bed of the Atlantic consists for the 
 mo.st part of two winding valleys, of 
 variable width and having an aver- 
 age depth of aboiit three miles, sepa- 
 rated by a rise whose mean distance 
 below the surface is not quite two 
 miles. This culminates in several 
 oceanic islands, and extends to the 
 Guiana coast, thus dividing the west- 
 ern valley into northern and south- 
 ern basins. 
 
 The deepest part of the Atlantic, 
 27,386 feet, is near the island of St. 
 Thomas, one of the West Indies. This 
 depression has been called Internation- 
 al Deep, independent soundings having 
 been made here both by English and 
 American oflBcei-s. 
 
 THE GULF OF MEXICO 
 
 Showin^ Deptta of Water and Direction of 
 
 Carre-it3, as determined by Commanders 
 
 Bartlett and Sigsbee, of U. S. Navy. 
 
 1000 fathoms-- 
 
 Dotted contour lines connect points of equal depth. Arrows show the currents which unite to form the Gulf Stream- 
 
54 
 
 THE INDIAN OCEAN. — THE POLAR OCEANS. 
 
 explanation: lilhcte, Snow ansl ice: Blue. Open M'ater; Dark Green, Forczt ixind^ Light Gram JBilsJi and GnoJis Landj BuJXt Tundra. 
 
 THE ARCTIC OCEAN AND NORTH POLAR REGIONS. 
 
 tbe Indian Ocean except through a narrow, sinuous channel, which 
 winds among tlie Spice Islands. 
 
 The Pacific is the deepest of the oceans as well as the most ex- 
 tensive in area. A large proportion of the North Pacific is as 
 much as four miles deep. This area is called Tuscarora Deep. The 
 greatest depth ever sounded in the ocean is 27,930 feet, more than 
 5^ miles, nearly equal to the height of the Himalayas. 
 
 This sounding was made Jmie 19, 1874, on board the United States 
 ship Tuscarora, by Captain George E. Belknap, latitude 44°, 55' north, 
 longitude 152°, 26' east, near the Kurile Islands. During the same year, 
 a sounding of 27,450 feet was effected on board the British ship Challen- 
 ger, near the Ladrone Islands. (Consult Captain Belknap^s '"Deep-Sea 
 Soundings in the North Pacific Ocean on the Steamship Tuscarora " ; 
 also Wild's " Thalassa.") 
 
 The Indian Ocean is deepest over an area extending west 
 of Australia and south of the Smida Islands, becoming gradually 
 
 shallower toward the Bay of Bengal. From Hindostan a plateau 
 extends southward, from whicli the Laccadive, Maldive, and Cha'gos 
 Islands rise to the surface. A similar plateau extends in a curve 
 from Madagascar, including the Seychelles, Mauritius, and Reunion 
 Islands. These two plateaus form in part a basin for the Arabian 
 Sea. 
 
 The mean depth of this ocean is between two and three miles. 
 Toward the south, it grows shallower and is interrupted by a few 
 scattered mountain elevations, such as St. Paul's, New Amsterdam, 
 Kerg'uelen, and Crozet (Iro-zay') Islands. 
 
 The Polar Oceans. — Little is known of the depth of the 
 Polar Oceans. In the northern part of the Atlantic, the two basins 
 unite and grow shallower, a plateau extending across from Green- 
 land to Scotland, with Iceland as its culmination. Northeast of 
 Iceland a basin is foimd, about three miles deep, which extends 
 
Nt)i:TII ANJ) SOITIl POI.AU KKdIONS. 
 
 55 
 
 
 
 ^^ 
 
 vicii no 
 
 
 
 A 
 
 xV 
 
 o 
 
 c 
 
 , :, ^^^' 
 
 ^--- v'^--'-' 
 
 .. .i.c»o»' 
 
 
 ^' 
 
 
 ^ 
 
 
 -■ , %;-. — ^ , 
 
 Xl \ ■5-.' -J^-^-tS) i _,--Ay. .■■ 
 
 <'■ 
 
 
 
 
 
 ■%. 
 
 
 
 HV 
 
 1 ?«f if 
 
 \ I / .......•■••■■*^ 
 
 Ay 
 
 ...SOWTH 
 
 '>??*.5 
 
 . 'W- 
 
 ^ \ "'•%:. 
 
 - . \ 
 
 \ V 
 
 
 ..■■■- ■■■■■:.. V h:<fy 
 
 
 -V — r ■ ^-*»...; i'- ' I.--. — ' ■.. 
 
 N^"" 
 
 c| ^ 
 
 4 /: 
 
 ^(. 
 
 V 
 
 
 y "^ / 
 
 ^^■' \.-^^A 
 
 ,,.••7^°^ 
 
 i^o" 
 
 vo 
 
 SI) Loii-itu<le 90 West 100 from no Orec-n\vi,li \lf\ 
 
 explanation: » /u7l', .Skou- (UI'7 /cc. Dine, Ojicn M atcr; Dark Green, Forest Lund; Light Green, Bush and Grass Land; Hed. Desert. 
 
 THE ANTARCTIC OCEAN AND CONTINENT, 
 
 iKirtliward to an unknown di.stance. The Arctic Ocean north of 
 Siberia is believed to be shallow. Soundinars have not been made 
 to such an extent as to give definite knowledge of the Antarctic 
 depths. {Consult M(U-kh<iiii\'i ^UTreat Frozen AVrt.") 
 
 The Polar Regions extend respectively from the Arctic and Ant- 
 arctic Circles to the North and South Poles, the distance between the 
 poles and the circles being- 1,408 geographical nules. Three million 
 square miles ^vithin the north polar circle, out of a total area of over 
 eight million, remain unexplored, and of then- physical geography noth- 
 ing is positively known. 
 
 The avenues of approach to either pole are blocked with " floes," 
 "ice-flelds," and "i)ack-ice." Exploring vessels making for Lancaster 
 Sound l)y way of Davis Strait, and whalers seeking the western cruising- 
 gi'ounds, have to cross the '' middle ice," formed farther north during the 
 winter and wedged in Baffin Bay in summer, and may choose one of 
 three routes — the Southern, along the lower edge of the pack ; the Middle, 
 between latitudes 68° and 74° ; and the Northern, to make which they 
 
 must keep to the Greenland coast, brave the appalling dangers of Mel- 
 ville Bay, and if they escape these bear westward fi-om Cape York. The 
 middle passage is seldom practicable; Parry made it in 1819, but failed 
 in a subsequent attempt in 1824. In the flourishing time of the whale- 
 fishery, thirty sail woidd sometimes be waiting for days for a favorable 
 opportunity to rim the gantlet and escape the Devil's Nip. 
 
 The South Polar Regions differ from the nortiiern in being 
 almost covered by the ocean. Tiie only extensive lauds he close to 
 the pole. 
 
 A Slif^ht Chaiigre of Sea-level would greatly modify the 
 present boundaries of land on the earth's surface. If it were de- 
 pressed 1(10 fathoms (about a forty-thousandth of the distance to 
 the eai'th's center) Great Britain would form part of the continent 
 of Europe; the bed.s of the North, Baltic, Black, and Adriatic 
 Seas, would be tlry ; NeW- York would lie a hundred miles from 
 
:.6 
 
 WAVES AND TIDES. 
 
 the coast ; and the southern end of Newfoundland would be east 
 of the inland city of Boston. If the sea-level were elevated 100 
 fathoms, London, Paris, New York, every large city in the world, 
 Avoiild be submerged, along with nearly half of North America, 
 three-fourths of Em-ope, a third of Asia, and half of South America 
 and Australia. 
 
 ftuestioas. — What proportion of the earth's surface is covered with water ? 
 Name the divisions into which the ocean is usually separated. How are 
 the gi'eat oceans connected ? Compare the two main oceans as to their 
 form, magnitude, depth, and floor. What would be the result if the sur- 
 face of the ocean were elevated 100 fathoms ? If depressed 100 fathoms ? 
 
 What can you say of the composition of sea-water ? Of the salts it contains ? 
 Its color, phosphorescence, density, pressure, and freezing-point ? State 
 what is known of the depth of the ocean. Discuss its temperature ; the 
 configuration of its floor. How far has the sea-bottom been investigated ? 
 
 Give an account of the Atlantic Ocean ; its bed, greatest depth, the inland 
 seas that open into it. Of the Pacific. Of the Indian. How much is 
 known of the Polar Oceans ? If the water occupied the polar regions, 
 leaving the equatorial for the land, would the earth better subserve the 
 purposes of man ? 
 
 MOVEMENTS OF TEE SEA-WAVES. 
 
 The sea is never at rest. The wind breaks its surface into 
 Waves, the sun and moon change its level by producing Tides, 
 and its waters are transferred from place to place by Currents. 
 
 Waves are ridges of 
 water produced by the 
 friction of the winds on 
 the surface. They ap- 
 pear to move forward ; 
 but in deep water it is 
 only the wave-form that 
 advances, each particle 
 in succession moving up 
 and down in an ellipse. 
 The dimensions of this 
 ellipse determine the 
 height of the wave, 
 which does not often 
 exceed ten or twelve feet. 
 Only in the most violent 
 storms have waves been 
 observed whose height 
 from crest to trough was 
 40 feet, and length from 
 crest to crest 550 feet. 
 
 Force of Waves. 
 
 — When a large wave 
 meets a shelving beach, 
 this retards the ellip- 
 tic motion of the parti- 
 cles near the bottom, 
 and the crest rolls for- 
 ward, breaking into 
 
 foam. Vertical motion is thus changed into horizontal motion. 
 The force with which the water thus strikes against an obstacle de- 
 pends upon the velocity of the wind and the time during which its 
 energy has been accumulating. It has been estimated, in a violent 
 storm, as high as forty pounds upon each square inch of surface 
 exposed. Waves are therefore powerful agents in wearing away 
 
 coasts, and thus increasing the inequalities of the outlines of the 
 land. 
 
 Duration of Wave-Motion.— Even after the wind has 
 lulled, the momentum acquired by the water is enough to keep it 
 long in motion. When the air is perfectly quiet the ground-swell 
 of the sea continues, and breakers roll on the beach. Only after a 
 calm of many days does the sea become perfectly smooth at its 
 surface. 
 
 Effect below the Surface.— The disturbance produced at 
 the surface is imparted to the water below to a depth not exceed- 
 ing the length of the wave. At depths of 50 feet, the water is 
 ordinarily unaffected. The commotion may be communicated sev- 
 eral hundred feet below the surface during the progress of a great 
 cyclone, but below 700 feet the water is probably never disturbed 
 except by currents. 
 
 Velocity of Transmission. — For great waves, whose 
 length exceeds the depth of the water, the rate of progress de- 
 pends on this depth as well as on freedom from obstructions. In 
 open sea, therefore, a wave travels faster than in a narrow bay. 
 
 In 1877 an earthquake-wave, starting near Arica on the coast of 
 Peru, crossed the Pacific Ocean, and reached Japan in twenty-four 
 hours, \vith a mean velocity of nearly 600 feet a second, or ten times 
 that of an express-train. The mean depth of the Pacific was thus calcu- 
 lated to be two miles. Such estimates are only approximate. In shallow 
 
 water, the velocity of a 
 wave's transit may be as 
 little as fifteen or twenty 
 feet a second. 
 
 TIDES. 
 
 Tides are the alter- 
 nate swelling and sink- 
 ing of .the sea in great 
 waves w-hich reach the 
 land at regular intervals. 
 
 The water rises, pro- 
 ducing iiood-tide; then 
 sinks, jjroduciug ebb- 
 tide a little over six 
 hours afterward. This 
 action is repeated con- 
 tinually, the interval be- 
 tween two flood-tides be- 
 ing nearly twelve hours 
 and a half. 
 
 Tide - waves dlifer 
 from ordinary waves in 
 the following particu- 
 lars : 
 
 I. They are caused 
 by the attraction of the 
 moon and sun, and not 
 
 Pir.EON-RocKS, Beirut, SvaiA ; illpstkating the Results of Wate-Action. 
 
 by the friction of the wind. II. The disturbance affects the water 
 as a mass, and is not coniined to the surface. 
 
 Production of Tides. — To understand the production of 
 tides, it is necessary to remember that, if a body is revolving around 
 any center, its course is due to the combination of two influences. 
 At every point it tends to continue on in a straight line, but the 
 
THE TIIEOKY OF TIDES. 
 
 t)l 
 
 central attraction makes it fall continiially toward the center. Its 
 direction i.s thus perpetually changing, and it never reaches the 
 center towai d which it is falling. 
 
 Let the student whh-I a ball which is secured to his hand by a string. 
 The hand rei)resents the earth, the ball is the moon, the pull of the 
 striu": ou it is like the earth's attraction. The ball is continually falling 
 toward his hand without reaching it. If the ball is released, it Hies off, at 
 fh'st in a straight hue. Moreover, to keep it whirling, the hand revolves 
 also in a small circle. The hand and ball move at different distances 
 around the same center. The pull of the string ou the baud is just equal 
 to iis pull on the ball. 
 
 The Lviiiar Tide. — Suppose two bodies like the earth and 
 moon to be revolviue; around a common center. Then each is con- 
 tinually falling towartl that center, both being pulled equally 
 toward it, the earth by the moon and the moon by the earth. 
 
 To illustrate, let E in the diagram represent the earth's center, and M that 
 of the moon. Imagine the earth to be a sphere completely covered with water 
 of uniform depth. A particle of water at a, being more distant from M than 
 E is, will be pulled less strongly ; hence a and E must become separated in 
 their fall, their distance apart becoming increased to E a'. The effect is the 
 same ns that of diminishing the earth's attraction on the w.ater at a. The 
 solid matter near a is affected likewise, but can not move from E. 
 
 M' 
 
 In like manner a particle of water at h, being nearer to M than E is, will 
 be iiuUed more strongly ; lieuee h and E must become separated in their fall, 
 their distance apart becoming increased to E h'. The water is thus drawn 
 away from c and rf, to become piled up at a and h. There is high tide at 
 l)oints aligned with the' moon, and low tide at points distant from these a 
 little over 6,000 miles. If the moon were covered with water, similar tides 
 would be produced on it by the earth's attraction. 
 
 But the eartli rotates daily. Suppose the top of a rock at e just to touch 
 the .surface of the water. Then, moving around with the earth, it will be 
 exposed at c, submerged at «, exposed at d, and submerged at h. During the 
 interval the moon has moved from M to M', so that the high tides will now 
 be aligned with M' ; and fifty-four minutes more than a day are required for 
 tlie rock to recover a position like that from which it started. The interval 
 between high and low tide is hence about six hours and thirteen or fourteen 
 minutes. If liigh tide occurs at noon, then on the next day the correspond- 
 ing tide must take ])lace nearly an hour after noon, an intermediate high tide 
 having occiured sliortly after midnight. 
 
 The Sohir Title. — The sun exerts also a tide-producing in- 
 fluence, but ou account of its great distance its effect is much less 
 than that of the moon. In New York Harbor, the difference be- 
 tween high and low water due to the moon is about four and a 
 half feet; that due to the snn, only one foot. In mid- ocean, the 
 sun's influence is about four-tenths of the moon's. 
 
 Spriiii? Jiiitl Neap Tides. — When sun and moon are in the 
 same line wit'.i the earth, whether on the same or opposite sides, 
 their effects are conjoined to produce tides higher than usual, called 
 spring-tides. When their directions from the earth are crossed at 
 right angles, the tide-producing influence of each conflicts with 
 that of the other, so that the tides are lower than usual. Such 
 tides are called iyMj)-tidi:s. There are two spring-tides during each 
 
 lunar month, produced by the new moon and the full moon ; and 
 two neap-tides, produced by the moon at fij-st and third quarters. 
 The highest spring-tides occur when the earth is nearest the sun, 
 and the moon £.t the same time nearest the earth. The opposite 
 conditions produce the lowest neap-tides. 
 
 Tidal Motion of the Water. — Since the water is piled up 
 in places of high tide at the expense of places of low tide, a tidal 
 waV'e implies a transfer of water along with the advance and reces- 
 sion of the wave over any point. The rate of progress of the wave 
 when once started depends on the depth of water and size of the 
 ocean. The tide moves fastest in the deep sea, and is much re- 
 tarded in approaching the shoals near the shore. 
 
 Height of the Tide. — In the middle of the Pacific Ocean, 
 the height of the tide is calculated to be but little more than two 
 feet. Where it approaches a shore, the retardation of the front of 
 the wave causes a piling of the water from behind, so that the dif- 
 ference between high and low water is much increased. This be- 
 comes specially marked where the wave advances into a recess, or 
 wedge-shaped bay. 
 
 On the east coast of the United States, there are three great recesses. 
 One is between Cape Florida aud Cape Hatteras, the inmost part being 
 at the mouth of the Savaruiah River. At these two cajjes, the height of 
 the tide does not exceed two feet, while at Savannah it is seven feet. 
 Tiie second recess is between Cape Hatteras and Nantucket, the highest 
 tides being at New York. The thu-d is between Nantucket and Nova 
 Scotia, with several minor bays. At Boston, the height of spring-title is 
 eleven and a half feet, aud in the Bay of Fundy it exceeds fifty feet. 
 Wind and tide together may raise the water seventy feet above its lowest 
 lioint at the head of this bay. 
 
 Bores. — When the front of a tidal wave is retarded, its slope 
 is increased, so that the tide at a given point rises ra])idly and falls 
 slowly. In the Severn Kiver, above Bristol, England, the whole 
 rise of eighteen feet is completed in ninety minutes, while the fall 
 occupies ten hours. At the time of spring-tide, the wave in ascend- 
 ing the river rashes violently like a billow eight or nine feet high. 
 Such rolling tide-waves in estuaries are called Bores. 
 
 Bores are observed at the head of the Bay of Fundy ; in the Dor- 
 dogne River, where it empties into the Garonne, on the coast of France ; 
 and in the Hoogly and Brahmaputra Rivers, at their point of entrance 
 into the Bay of Bengal. In the Chinese river Tsien-tang, the bores are 
 thirty feet high and travel over twenty miles an hour. In the Amazon, 
 at the time of highest tides, bores ascend the river to a distance of 200 
 miles, as many as sis or seven of them appearing in succession dur- 
 ing three days, like rolling terraces of water, twelve or fifteen feet in 
 height. 
 
 Retardation of the Tidal Wave. — When the moon is 
 most nearly overhead, its tide-producing inllueuce is strongest. 
 But the time of high tide does not actually occur until several days 
 afterward. This is due to the fact that the momentum acquired 
 by the water in rising causes the aecumidation to continue at any 
 place after the tide-producing influence has begun to diminish. 
 Water can not move without friction, and this also greatly retards 
 the production of the tide-wave. The velocity of the wave, more- 
 over, being greatly affected by the varying depth of the ocean and 
 the irregularities of coast-lines, can never approach that of a point 
 on the earth in its rotation. 
 
 Even if formed just under the moon, the tide-wave can not 
 keep such a position in regard to it. The eastward velocity of a 
 point on the E(|uator is over 1,000 miles an hour. The westward 
 velocity of a tide-wave rarely exceeds 500 miles an hour. 
 
58 
 
 CO-TIDAI- LINES. 
 
 Chakt or Co-tidal Lines, illustrating the Course of the Tidal Wave in the Four Great Oceans. 
 
 Co-tidal LiineSo — If a tide-wave be assumed to start at a 
 particular meridian, and its successive positions be represented by 
 corresponding lines on a chart, these will not coincide with the 
 successive meridians. 
 
 The South Pacific Ocean, being most nearly free from obstruc- 
 tion, is assumed as the starting-place of the tide-wave. As this ad- 
 vances, its rate becomes varied by obstructions. Lines connecting 
 those places which have high water at the same moment, are called 
 Co-tidal Lines. 
 
 By refeiTing to the Chart of Co-tidal Lines, it will be seen tliat 
 the high tide which occurs at noon in the middle of the South Pacitic 
 reaches New Zealand and Kamchatka about six hours afterward. The 
 wave-front becomes greatly bent in the North Pacific, so as to approach 
 Alaska from the south and California from the west. Traveling west- 
 ward, it reaches the longitude of South Africa before noon on the 
 following day, but has been much retarded in equatorial regions, so as 
 to approach India from the south. By noon of the second day, a part of 
 it has traversed the Atlantic in a northwestward direction and reached 
 the North American coa.st ; while about the same time, another part, 
 much retarded on the eastern side, has arrived at the western coast of 
 Africa, near the Sahara Desert. Advancing toward the northeast, it 
 touches Iceland and Scotland six hours later ; and at midnight it has 
 passed Norway and nearly reached Spitzbergen. 
 
 Opposition of Tide -Waves. — Owing to retardation in 
 shallow water, the parts of a tide-wave in passing around a large 
 island may meet on its farther side in different phases, so as to 
 produce much distui'bance and rapid local currents. 
 
 In New York Harbor at about seven and a half hours after the 
 passage of the moon, high water enters between Sandy Hook and Coney 
 Island with an elevation of four and a half feet. At the same time it 
 passes the east end of Long Island with an elevation of two feet, and 
 
 travels thence through the Sound toward New York. Meanwhile, the 
 wave from Sandy Hook has slowly traversed New York Bay and as- 
 cended the East River. The meeting-place of these two tide-branches is 
 at Hell Gate, the narrowest ship-passage between Long Island and New 
 York. Differing in times and heights, they cause the surging currents 
 that periodically sweep through the East River. If a partition-wall were 
 built across the river at Hell Gate, the water would at times be five feet 
 higher on one side than on the other, reversing the inequality with each 
 change of tide. There is no actual opportunity for such an accumula- 
 tion, but a difference of a foot in height within one hundred feet in dis- 
 tance is not uncommon. 
 
 Somewhat similar conditions exist in the British Channel, the tidal 
 wave that i^asses through the Strait of Dover being met by another that 
 has turned around Scotland and traveled southward through the North 
 Sea. The roughness of the water in the Channel is well known. 
 
 Wliirlpools,— Opposing currents, tides, and sometimes winds, 
 produce the phenomena of eddies and wliirlpools. Tidal currents 
 round the Lofo'den Islands, off the Norwegian coast, cause the 
 famous Maelstrom {grinding strcmri), a mile and a haK in diameter. 
 In certain states of the wind and tide, the Maelstrom is entirely 
 unnavigable ; vessels caught in the current are in danger of found- 
 ering, or of being dashed to pieces against the rocks. Ancient 
 accounts represent this whirlpool as swallowing up ships and mon- 
 sters of the deep ; they are mere fables, for there is no reason to 
 suppose that the violence of the Maelstrom has lieen modified in 
 recent time by geological changes in the rocks about which it roars. 
 
 Near the island of Jura, off the west coast of Scotland, the whirlpool 
 Corryvreck'an is produced by the opposition of a pyramidal rock to the 
 tidal stream. Two whirlpools formidable to the ancients were Scylla 
 and Charybdis. on opposite sides of the Strait of Messina. ■ They stiU 
 exist, but are no longer associated with danger to navigation. 
 
THEORY OF O CE A N -CURRENTS. 
 
 .'^9 
 
 CCRVE OF THE TiDAL WaVE ABOUT THE 
 
 British Isles. 
 
 Questions.— Explain the na- 
 ture of waves. Illustrate 
 the force of waves; their 
 velocity. How far below 
 the surface is the disturb- 
 ance felt ? How long ? 
 Explain the jihenomena of 
 tides; the .solar tide ; the 
 difference between tidal 
 and ordinary waves ; be- 
 tween spring and neap 
 tides. What are bores ? 
 AVhere are they observed ? 
 Briefly state the history 
 and progress of the Atlantic tide-wave, mentioning its magnitude in open 
 water, and the time it occupies in making the tour of the coast-line of the 
 United States. Explain the retardation of the tidal wave. What are co- 
 tidal lints ? Trace the course of the tide through the East River ; around 
 the British Isles. In what waters does the tide attain its greatest height ? 
 Suppose at new moon we should have high tide at mid-day, why would 
 the opposite side of tlie earth have high tide at the same hoiu" ? 
 Discuss the cau.ses of whirlpools. Describe the Maelstrom; the Corryvreckan. 
 Where were the ancient Scylla and Charybdis ? 
 
 OCEAM-CTJRREMTS. 
 
 The sulijeet of ocean-currents is so intimately relat'jd to that of 
 tlie great currents of the air that any discussion of the principles 
 involved iu one must apply at leasi; partially to the other also. 
 
 Theory of Oceaii-Ciirrent.s. — Suppose the earth to be at 
 rest and entirely covered with water of uniform dejith. Let it be 
 heated aloua; the Equator and cooled at the poles to the bottom, so 
 tliat eijiuitorial waters are expanded and polar waters are made 
 more dense. The level of the warm water is by expansion raised 
 slightly above that of tlie cold water. A current always tends to 
 fl(-w from a higlier to a lower level, therefore a surface-current 
 must How fi'om the Equator toward each of the two poles. For 
 the water thus ivinoved, a supjily of cooler water must come as an 
 undercurrent from tie polar regions. A constant circulation is 
 thus established, tending to equalize the temperature of the earth's 
 waters. 
 
 Let the earth now rotate on its a.^is. The surface velocity eastward 
 is over 1,000 niile.s an hour at the Equator, diminishes to 500 miles near 
 latitude (>0°, and is reduced to zero at the {)oles. This motion belongs to 
 all objects at the surface. The cold water, pa.ssiiig from slow-moving 
 polar to fast-mo\'ing equatorial regions, can not instantly assume the 
 increased rate eastward. The ocean-bed passes eastward under it, and 
 therefore these currents gradually assume a westward du-ection iu re- 
 
 lation to the fast-moving ground, imtil they nearly reach the Equator. 
 Here they rise to the surface as westward currents, and tlien overflow 
 toward the ])()les after becoming warm. 
 
 Tliese surface-currents now pass off toward the slow-moving polar 
 rii;ions, cai'iyiug with them the rapid eastward velocity acquired at the 
 Etpiatoi". They therefore 
 manifest this by sweeping 
 eastward over the waters 
 underneath, until they 
 reach the polar regions. 
 Here they sink and re- 
 sume their journey bt;- 
 neath toward the Equator. 
 
 In the figure, the west- 
 ward equatorial current is 
 indicated by the arrow, 
 a J/ the overflowing warm 
 currents, by c d, d d'; the 
 eastward currents in the 
 neighborhood of the polar 
 circles, by cj\ e'f; the un- 
 dercurrents of cold water, 
 by fjh, d'h', represented in 
 dotted lines. 
 
 Ferrel's Liaw. — It has been proved mathematically by Pro- 
 fessor Ferrel that " //; tolmtever direction a hody moves on the sur- 
 face of the earth, there is a force arising from the cartKs rotation, 
 which deflects it to the right in ths northern hemisjphere hut to the 
 left in the southern.'''' 
 
 This is known as Ferrel's Law. On it is based the theory of both 
 oceanic and atmospheric currents. Each straight arrow in the figure 
 touches a curve that bends to the right of the arrow-head in the north- 
 ern hemisphere, to the left in the southern hemisphere. At the Equator 
 the opposite forces are equal. (Consult Ferrel's article on " The Motions 
 of Fluids and Solids on the Earth's Surface,'' in ''Professional Papers 
 of the United States Signal Service," No. viii., pp. 30-51.) 
 
 3Io(lifying Influences. — The exact circulation just de- 
 scribed is not realized in full, because the continents serve as ob- 
 structions, and also because the polar waters have a lower tempera- 
 ture at the surface than at the bottom. The comparatively warm 
 water at the bottom tends to rise and displace the colder and 
 heavier surface-water, making this How outward before it can sink. 
 Cold surface-currents from the poles, therefore, move for a short 
 distance toward the Equator, becoming deflected to the west, and 
 sinking under the warm currents that they meet. These in turn 
 sink as they become coded by mixture and by the cold air. 
 
 The wind, especially where it blows constantly in one direction, has 
 a decided influence in determining the direction of the surface-currents 
 of the ocean. Indeed, some authorities consider the wind the most 
 important of all agencies in producing currents. But the depth of cer- 
 tain ocean-ciu'reuts is too great to be accounted for by the action of the 
 wind alone. 
 
 Atlantic Currents. — In the Atlantic Ocean, about equa- 
 torial regions, there is a general movement of the water westward. 
 This fact was discovered by Columbus, and is most noticeable in 
 those parts which are swept by the trade-winds. 
 
 The north equatorial current flows from the Cape Yerde Islands 
 to the West Indies. The south equatorial divides near Cape St, 
 Roque, one part turning southward along the Brazilian coast as far 
 as the latitude of the La Plata Pivcr. Here it gradually bends 
 eastward and becomes lost by mingling with cold waters from the 
 South Frigid Zone. The other and larger portion flows past the 
 mouth of the Amazon and unites with the northern current, east 
 of the Lesser Antilles. 
 
60 
 
 THE GULF STREAM AND SARGASSO SEAS- 
 
 Origin of the Gulf Stream. — Between the Lesser Antilles 
 and the South American coast, an offshoot of the equatorial current 
 enters the Caribbean Sea, in the deep basin of which it is partially 
 checked by a shoal extending from Hondm-as nearly to Jamaica. 
 The current is thus turned round so as to pass eastward along the 
 south coast of San Domingo, and rejoin the main current near 
 Puerto Eico. This washes the north shores of Puerto Rico and San 
 Domingo, and is divided by Cuba into two streams, one of which 
 Hows on its north side to the Bahama Banks. The other passes 
 through Bartlett Deep, then turns northward through Yucatan 
 Passage, then eastward through the Florida Strait, where it unites 
 again with the other stream. Here, at its narrowest part, its width 
 is but little over forty miles, the depth does not exceed 3,000 feet, 
 and the velocity at the middle is nearly five miles an hour. 
 
 This narrow stream is thus only a moderate part of the great body 
 of warm water which flows from tropical to north temperate regions. 
 Little, if any, of it cu-culates through the Gulf of Mexico. It is swelled 
 iu volume at and beyond the Bahama Banks by the rest of the great 
 current, and to the whole, as it flows to the northeast, the name of Gulf 
 Stream is appUed. This name is the result of a misapprehension, as it 
 was formerly thought that this body of water made the circuit of the 
 Gulf of Mexico. 
 
 Temperature and Ueptli of tlie Gulf Stream. — The surface 
 temperature of the water at the Lesser Antilles is usually 79° or 80°, and 
 between Cuba and Floi-ida it is 82°. Tliis rapidly decreases with depth, 
 untU at 4,800 feet it is 39^°. The cui'rent sweeps the bottom from Cuba 
 to South Carolina, and widens as it passes over a broad plateau whose 
 general depth is 3,400 feet. It washes the ground bare, so that where the 
 stream is fastest the only specimens obtained by sounding are pieces of 
 hard coral rock. 
 
 North of latitude 33°, the current ceases to sweep its bed ; for here a 
 dark, greenish ooze, characteristic of the North Atlantic, begins to be 
 found on the bottom indicating that at tliis point the heavier waters 
 
 .■^:,:n Off-- m^-'-mfl \'^. '%^\ 
 
 / »0*^ 
 
 
 MAP OF THE 
 
 CARIBBEAN SEA 
 
 SnnwlM; THE 
 
 VARIOUS DEPTHS OF WATER AND THE 
 DIRECTiON OF CURRENTS, 
 As determinod byCnmraandor rortlptt. of the U.S. 
 ^^__^ Na\-j. The dei3ths are marked ui fathoms. 
 
 of the cold current from the Arctic regions are displacing tliose of tlio 
 Gulf Stream. The warm water glides over its co(jler liquid bed, uiitd 
 near Cape Hatteras tlie surface is alternately cold and warm. Here 
 the Gulf Stream becomes divided into bands, as it gradually changes its 
 direction toward the east and widens stUl more as its temperature falls. 
 Near Newfoundland its width is 320 miles, and its velocity is reduced 
 to a tliird of what it was off the Florida coast, while the quantity of 
 water moving eastward is doubled on account of accessions from tlie 
 streams tliat flowed past the Antilles without entering the Caribbean 
 Sea. Off the west coast of Europe, the velocity hardly exceeds one hun- 
 dred yards an hour. {Consult Bartlett in '^Journal of the American 
 Geographical Society,^'' vol. xiii., ISSl.) 
 
 Division of the Gulf Stream. — Crossing the Atlantic, 
 part of this stream turns southward past the coast of Portugal and 
 Africa, completing the circuit as it rejoins the north equatorial 
 current. Another branch continues its northeast course past Great 
 Britain, Iceland, and Norway, until it is mingled with the waters 
 of the Arctic. A small current washes the southern part of Green- 
 land, ojDposite Labrador. 
 
 Contrasts presented by the Gulf Stream. — The sur- 
 face temperature of the Gulf Stream is such as to warm all the 
 land near which it passes. It makes Norway habitable, and keeps 
 the harbor of Hanmierfest free fi'om ice, although this town is 
 within the Arctic Circle. At the same latitude in America, a 
 severe Arctic climate prevails. In passing into the Gulf Stream 
 near Halifax, a difference of 30° in temperature has been recorded 
 during the same day, and of 8° or 10° in as many minutes. 
 
 The color of the Gulf Stream is the deepest azure, presenting a 
 remarkable contrast to the greenish tint of the neighboring colder 
 water. The difference between the water at the bow and that at 
 the stem of a large ship, in tint as well as in temperature, is some- 
 times noticeable, esjpecially in the seas near Newfoundland. 
 
 Sargasso Sea. — The com- 
 pleted circuit of the equatorial cur- 
 rent and Gulf Stream causes the in- 
 closed mass of still water to become 
 a receptacle for floating bodies gath- 
 ered by the current. These include 
 an immense quantity of sea-weed 
 which covers thousands, of square 
 
 CO" 
 
 •...^wqo..^ 
 
 
 [,...15^ 
 
 I 
 
 y^'' ii\ 
 
 
 The clotted contour lines connect places of equal depth. The ari'ows show the currents which form part of the Gulf 
 
 Stream, but without circulating thro'agh the Gulf of Mexico. 
 Where the slope of the sea-bottom is steep, the dotted contour lines are close together. The direction of slope is shown 
 
 by the numbers. Thus, on the north side of Bartlett Deep, the depth diminishes from 3,000 to 1,000 fathoms ; 
 
 on the south side, from 3,000 to 500 fathoms. 
 1.000 fathoms = 1 nautical mile, nearly. Compare with map on p. 53. 
 
 miles of surface. It grows without 
 roots, and afl[ords a home to multi- 
 tudes of fish. Mingled with these 
 marine grasses are occasional masses 
 of drift-wood. The name Sargasso 
 (sea-weed) Sea is applied to such 
 areas, of which several have been 
 found in the ocean. (See p. 50^ 
 (Consult Dr. Ilartroufs '■'•The Sea 
 and its Liv'tny Wonders,'''' p. 399.) 
 
 Atlantic Polar Cvirrents. 
 
 — From the Arctic Ocean, a polai' 
 current sets southward. A narrow 
 band of this cm-rent washes the east 
 coast of Greenland ; but the largest 
 portion flows through Baffin Bay and 
 extends southward until it meets the 
 Gulf Stream. The earth's rotation 
 causes this cold current to keep close 
 to the western shores of the chan- 
 nel (Ferrel's Law). Labrador and 
 
ARCTIC AND PACIFIC CURRENTS. 
 
 61 
 
 Newfoundland are therefore frozen wastes during mucli of the 
 year, and the inHnence of its chilling presence is strongly felt on 
 the coasts of Maine and Massachusetts. Where it meets the Gulf 
 Stream, much sediment is deposited, thus forming the Banks of 
 Newfoundland. 
 
 Another cold current flows southward past Spitzbergen, and is 
 limited, like the BafTin Bay current, by the advancing Gulf Stream. 
 The southern limit of tloating icebergs is determined by the conflict of 
 these cold and warm currents. 
 
 From the Antarctic Ocean, the cold water flows northward with 
 little or no obstruction. The prevailing winds, which are con- 
 stantly toward the southeast, give an eastward deflection to these 
 currents at the surface over the whole southeni ocean. Passing 
 into tlie Atlantic, the Antarctic current washes the western coast 
 of South Africa, making its cooling influence felt nearly to the 
 Equator. 
 
 Pacific Equatorial Currents. —Across the 8,000 miles of 
 the Pacific Ocean, a broad current sets westward with a speed esti- 
 mated at from two to three miles an houi-, being strongest in the 
 trade-wind regions north and south of the Equator. About the 
 middle of this strip there is a perceptible counter-current, setting 
 east. This is due to the interruption opposed by the archipelago 
 between Asia and Australia. Each of tlie two streams becomes 
 banked up and tends to spread on lioth sides. The portion thus 
 thrown off between them can only return between them. 
 
 Much the greater part of the northern current is deflected north- 
 ward. Of the southern current, a very small part may penetrate through 
 the Archipelago to the Indian Ocean, but most of it turns southward 
 past Australia and New Zealand, and becomes mingled with the cold 
 waters coming from the Antarctic Ocean. 
 
 The Japan Current, or Kuro-Siwa. — The north equa- 
 torial current for the most part turns northward in the neighbor- 
 hood of the Philippine Islands, and then sets northeastward. It 
 does not attain the velocity of the Gulf Stream, because its waters 
 are nowhere pent up in a basin with narrow channels analogous to 
 the Caribbean Sea. 
 
 The magnitude of the Japan Current is estimated to be about 
 three times that of the Gulf Stream. Its name, Kuro-Siwa, means 
 " Black Stream," and is applied on account of the dark-blue tint of 
 its waters. East of Japan, it spreads out and divides into branches, 
 the largest of which reaches the coast of Alaska, and imparts the 
 remaining warmth brought from tropical regions, just as the Gulf 
 Stream warms Norway. {Read AntisdVs article on '^The Cur- 
 rents of the Pacific Ocean,^'' in the Bulletin of the American Geo- 
 graphical Society, No. 2, 1883.) 
 
 Arctic Current. — The only connection between the Arctic 
 and Pacific Oceans is through Bering Strait, which is about forty- 
 five miles wide and less than 170 feet deep (Dall, 1880). In the 
 middle of the strait lie the Diomede Islands. It is impassable for 
 icebergs, but field-ice is borne southward into Bering Sea, and a 
 cold current of very small volume passes along its western half, dis- 
 appearing at no great distance from the strait. Bering Sea is thus 
 perceptibly colder than the ocean south of the Aleutian Islands. 
 
 The difference of temperature on the opposite sides of the projecting 
 peninsula of Alaska is very marked. On the south side, hummiug-birds 
 are found in summer; while the north side is visited at all times by 
 walruses and thousands of seals. 
 
 Peruvian and Antarctic Currents. — The western coast 
 of South America receives part of the Antarctic Current, after it 
 has reachefl the Pacific Ocean, just as Africa receives that in the 
 
 Atlantic. The shores of Patagonia and Cape Horn are therefore 
 bleak and frozen. Part of the cold current sweeps past Chile and 
 Peru, and then turning westward is lost in the south equatorial 
 current. 
 
 In the neighborhood of Australia, the Antarctic Current sends 
 a l)ranch that washes the western coast of this continent, and is 
 finally lost in the Indian Ocean. Another branch, flowing north- 
 ward, is deflected west by Tasmania, and to the southern coast of 
 Australia, returning upon itseK. The part which flows toward the 
 northeast between Tasmania and New Zealand mingles with the 
 south equatorial current, and the two together attain a velocity as 
 high as one hundred miles a day. 
 
 Currents of the Indian Ocean. — In the Indian Ocean 
 north of the Equator, the currents are regulated entirely by the 
 winds. South of it, there is a steady westward drift, the current 
 dividing into two parts near Madagascar. One of these sweeps 
 southward, east of this island, and joins the eastward Antarctic 
 drift. The other and larger part flows between Madagascar and 
 Africa to the extremity of the continent, where, under the name of 
 the Agulhas {ah-gool'yahs) Current, it is tui-ned sharply eastward 
 by the Antarctic drift, and penetrates far southward. 
 
 General Considerations.— "Where currents differing widely in 
 temperature meet each other, the sea is often covered with fog, and is 
 subject to sudden and violent storms. Among the best known of such 
 regions are the Banks of Newfoundland, the vicinity of Cape Hatteras, 
 of Cape Horn, and of the Cape of Good Hope. 
 
 Oceanic currents are the most important of all agencies in modify- 
 ing climate and producing uniformity in the temperature of the ocean 
 itself. Moreover, their constant circulation keeps the waters of the 
 ocean pure by preventing stagnation. Seeds are transported by them to 
 coral islands, and regions that would otherwise have remained deserts 
 have, through their agency, been rendered fertile and habitable. 
 
 The great amount of evaporation in equatorial regions causes the 
 water of the sea to become perceptibly more briny in low than in high 
 latitudes. 
 
 Evaporation alone is capable of producing permanent currents. The 
 Mediterranean Sea loses by evajjoratiou more water than it receives from 
 its shores. It is hence more salt than the Atlantic, and its surface at 
 Marseilles is about three feet lower than the surface of the English 
 Channel. A strotig current continually pours La at the Sti-ait of Gibral- 
 tar. For similar reasons there is a continual surface inflow from the 
 Indian Ocean into the Red Sea and Persian Gulf. In the case of the 
 Baltic Sea and Hudson Bay, evaporation is not sufficient to balance the 
 accessions of fresh water froni the surrounding basins. The water is 
 deficient in saltness, its tint is greenish-blue, and ctirrents flow continu- 
 ally out to the ocean. 
 
 Currents due to these local causes should not be identified with the 
 great ocean-currents of the globe. Evaporation tends to lower the sur- 
 face of the ocean in tropical regions and to make sea-water denser ; the 
 expansion due to heat at the same time tends to raise the surface and 
 make sea-water less dense as long as it is warm. It may not be possible 
 to decide which of these influences predominates. The direction of cur- 
 rents, due to either cause, is determined by the earth's rotation and the 
 friction of the prevailLag winds. 
 
 ftuestions. — Why are there currents in the ocean ? Recite Ferret's Law. 
 What theories are based on it ? By what iniluences is the natural circula- 
 tion in the ocean modified ? Describe the Atlantic currents. Account 
 for the Gulf Stream. Why is the name Gulf Stream a misnomer ? State 
 the temperature, color, mean depth, width, and velocity of this current. 
 Describe its course. What are Sargasso Seas ? 
 
 Give an account of the Pacific, Peruvian, Arctic, and Antarctic currents; of 
 the currents of the Indian Ocean ; of the Black Stream of Japan. How 
 do stream-currents difier from the tidal current ? How far are the direc- 
 tion and force of currents influenced by the form of the land ? Of what 
 utility are the oceans in the economy of nature ? Ocean-currents ? 
 
THE EARTH'S ATMOSPHERE. 
 
 The Third Geographical Elenient — Air. — We have 
 now considered the structure and physics of the earth's crust, its 
 land and its water, and ai-e prepared to investigate the more strik- 
 ing phenomena of that invisible elastic fluid which comj^letelj sur- 
 rounds our globe — the Atmosphere. The atmosphere (from two 
 Greek words, meaning vapor-splwre) is a vast gaseous ocean, the 
 greater part of whose mass is comprised in a Ia)'er having nearly 
 tlie same depth as the liquid ocean. Under the head of Atmos- 
 phere are to be studied the composition and general properties of 
 air; its circulation in winds ; its clouds and precipitations,' stoims, 
 t-lmiate, and weather. 
 
 The science that describes and explains those phenomena of the 
 atmosphere which may be conveuiently grouped under the head of 
 weather and climate, is known as Meteorology (literally, description 
 of things in the air). 
 
 Air is a Mechanical Mixture, chiefly of two gases, oxy- 
 gen and nitrogen ; of these, the former, in a free state, is necessai'y 
 to life. Although oxygen is a little denser than nitrogen, the two 
 are uniformly mixed, in the proportion by bulk of twenty-one to 
 seventy-nine, by weight of twenty-three to seventy-seven. There 
 are minute quantities of other permanent gases, the most impor- 
 tant of which is carbonic acid {see jp. 36), normally present in 
 the proportion of three pounds to 10,000. This 
 ratio is often trebled in crowded rooms. ^ ^^:- _--- .3 ^ 
 
 Invisible vapor of water is always present in 
 variable quantity, and fine particles of dust float 
 in the atmosphere, not only at the earth's sur- 
 face but at great elevations. (On the constitu- 
 ents of the air we breathe, consult Johnstoii!s 
 " Chemistry of Common Life^'' p. 13.) 
 
 Weight and Pressure of the Air. — 
 
 At the temperature of melting ice, 773 cubic 
 feet of air weigh ouly as much as a single cubic 
 foot of pure water, or nearly 62|- pounds. One 
 cubic foot, therefore, weighs about au ounce and 
 a quarter. 
 
 Since air is a perfect fluid, its particles are 
 freely movable among themselves. Each is sub- 
 ject to the weight of all those above it, and 
 transmits this as pressure equally in all dii'ec- 
 tions against those in contact with it. 
 
 The Barometer. — The pressure of the 
 air is determined by means of the Barometer 
 {weight-measitrer). Of several forms of this 
 instrument, the most familiar is that devised 
 by an Italian physicist, Torricelli. 
 
 A glass tube, three feet long, and closed at one 
 end, is filled with metallic mercury ; it Ls then in- 
 verted with its open end in a cistern of the same 
 liquid. The mercury in the tube falls until its level 
 is about thirty inches above that in the cistern. Its 
 weight is balanced by the pressure of the external 
 air upon the exposed liquid. 
 
 A column of mercui-y thirty inches long there- 
 fore weighs the same as a column of an of the same 
 diameter extending up to the extreme limit of the atmosphere. Such a 
 column of mercury, if its cross-section be a square inch, weighs 14.7 
 pounds. At sea-level, therefore, the pressure of the air is in all direc- 
 tions 14.7 pounds on each square inch of sm-face. 
 
 
 Barometer in its 
 plest foem. 
 
 Variation in Atmospheric Pressure. — As we ascend 
 above the lower layers of the atmosphere, the pressure is diminished, 
 the air becoming less dense because the overlying mass is smaller. 
 At a height of 3.4 miles, half of the atmosphere is left below, and 
 the barometer registers only fifteen inches. By calculation it is 
 found that at an elevation of thirty-five miles there is only ^^j-j-j-j 
 of the atmosphere beyond, and the barometric column would be 
 only YoViT inch high. Beyond forty miles the amount remaining 
 would be too small to ajfect the sun's rays perceptibly in any way, 
 and for practical purposes two hundred miles may be assumed as an 
 extreme limit. (On the pressure of the atmosphere, see Scotfs 
 ^^ Elementary Meteorology" p. 63.) 
 
 Barometer 
 in inches. 
 
 DIMINUTION IN DENSITY AND PRESSURE OF AIR WITH INCREASE OF HEIGHT, 
 
 Mass of the Atmosphere. — The entire mass of the atmosphere is 
 
 estimated to he about - 
 
 of that of the whole earth. The highest 
 
 mountains penetrate through nearly three-fourths of this mass, and 
 hence interfere largely with its motion over coutineuts. If the atmos- 
 phere were of uniform density, the same as that at sea-level, instead of 
 diminishing with elevation, its height would be about five miles, and the 
 barometer would fall an inch for every 875 feet of ascent. The highest 
 peaks of the Himalayas would pierce entirely through. 
 
 CLIMATE. 
 
 By Climate is meant the state of the atmosphere in regard 
 
 to the conditions that make it favorable to human welfare. The 
 most important of these are the temperature of the air, the amount 
 of moistm-e it contains, and the character of the winds. 
 
 Tempei'ature of the Air. — The air receives its tempera- 
 ture partly Ijy direct radiation from the sun, and partly by return 
 from the earth. Most of the heat it dei'ives from the earth is 
 what has been first transmitted through its own substance, absorbed 
 by the soil, and. then returned. The amount of heat conducted 
 from the earth's hot interior, through its crust, to the air, is very 
 limited. 
 
 Solar Radiation. — What the earth receives from the sun is 
 called solar energy. This is i-adiated in waves so minute that of 
 those which reach the sea-level the longest that have been measured 
 
EFFECT OF ELEVATION ON CLIMATE. 
 
 f!?. 
 
 are aLout , a'„ , . , inoli, and tlie shortest 1^7557)75- inch in leiif^th. Be- 
 tween these limits of wave-length, all the rays of solar energy con- 
 vey heat ; they produce chemical changes, as in the gi'owth of 
 plants; and those whose ■wave-length is between t-uJ^jj-j and ^rjyj-j-jj- 
 inch also affect the eye with the sensation of light. Those of 
 longest and shortest wave-length are hence called dark rays. 
 
 Of rays which are manifested as light, those of gi-eatest wave- 
 length, besides conveying heat, and chemical energy, produce the 
 sensation of red. With decreasing wave-length, the corresponding 
 sensations are orange, yellow, green, blue, and violet. The mixture 
 of all these rays produces the sensation of white. 
 
 Absorption of Solar Enerjyy. — No known substance 
 transmits solar energy without absorbing some of it at the same 
 time. Of solids, rock-salt transmits much of the lieat as well as 
 light ; quartz, much of the chemical energy as well as light ; com- 
 mon glass transmits each kiud, hut with great absorption of both heat 
 and chemical energy-. When the sun is in the zenitli, the atmos- 
 phere absorbs more than one-third of the solar energy that would 
 otherwise reach the sea-level, and far more than this proportion when 
 the sun's rays are oblique. It absorbs the rays of short wave-length 
 to a much greater extent than those of. long wave-length. 
 
 If all the rays of solar energy were like those of violet light, with a 
 wave-length of ^-gl^^ inch, only about 40 per cent, would reach the soil. 
 If all were of dark heat, with a wave-length of -rrm inch, fully 90 per 
 cent, would be transmitted. The qiiahty of the atmosphere by which it 
 seems to select certain rays for transmission and othei'S for absorption 
 is called its power of select ire absor2}tion. 
 
 As we ascend to great heights, not only does the air decrease in 
 density, but, quite indeijeudently of this, its power of absorbing solar 
 energy decreases also, and at a rate which varies with the wave-length. 
 The light that enters the eye at the top of a lofty mountain is much 
 richer in the short violet waves ; hence the tint of the sky is a mixture 
 of deep blue and violet, and the body of the sun looks bluish. But at 
 sea-level tlie sky is pale blue, and the sunlight, which we call white, is 
 yellowish. Our atmosphere thus transmits the long waves of solar 
 energy at all elevations, but only at great heights does it transmit any 
 large proportion of the short waves. 
 
 Minute particles of matter, floating as dust in the air, impede the 
 rays of solar energy, reflecting and absorbing those of shortest wave- 
 length, and transmitting a larger proportion of tliose of longer wave- 
 length. The light that reaches the eye, being thus deprived of its 
 usual amount of violet, appears reddish. To this fact is due the red- 
 ness of the horizon in the direction of the morning or evening sun, espe- 
 cially when the air is charged with vapor. Dust floats hi the air even 
 above the highest mountain-tops, but by far most abundantly near the 
 ground. 
 
 Effect of Elevation on Temperature. — Since the at- 
 mosphere absorbs heat more rapidly in its lower and denser parts, 
 taking this not only directly from the sun but also from the 
 surface on which it rests, it serves as the most important of all 
 accunnilators and distributors of heat over the land. At sea-level 
 it absorbs so much heat as at times to check further effective radia- 
 tion from below, and thus tends to produce uniformity of climate. 
 
 At great elevations the absorption is less, the air is cooled also 
 by expansion, and the general temperature is thus lowered. Be- 
 yond certain limits of height, even in the torrid zimo, the cold is 
 such as to keep the ground perpetually covei-ed with snow. Yet 
 even on' this snow, a good absorlier, like the human body, when 
 placed in direct sunshine, becomes temporarily heated, so that the 
 rapid changes of temperature are very distressing. On the whole, 
 the temperature of the earth's surface is due chiefly to selective 
 absorption in our atmosphere, and in only small degree to direct 
 solar radiation. 
 
 Temperature beyond the Atinospliere.— Our knowledge of 
 the selective absorption of the atmosphere is ilue very largely to the 
 labors of an American physicist, Profes.sor S. P. Langley. As the re- 
 sult of a long series of experiments, conducted with the utmost skill and 
 care, he estimates that, if the atmosphere were removed from the eai'th, 
 tlie temiM'rature of the soil in the tropics under a vertical sun would be 
 reduced far below zero, probably down to — IJiS" Fahr. 
 
 The temperature of spsice beyond our atmosphere is estimated to be 
 — 4(i0° F. The average temperature of the eai-th's surface is about CO' F., 
 or 388° higher than it would be without the selective absorption of the 
 atmosphere. The chtference between the warmest and coldest days in 
 New York rarely exceetls 90°, which is hardly moie than one-fourth of 
 what the atmosphere secures by its absorption. 
 
 Terrestrial Enerjfy Wave.s. — When the waves of solar 
 energy are absorbed by the air or soil, they are radiated again as 
 longer waves, far exceeding in length most of those received from 
 the sun. From bodies thus but slightly warmed. Professor Lang 
 ley has measured waves of nearly ^^ inch, or almost twice the 
 greatest length of solar waves tlius far measured. Air in con- 
 tact with a portion of ground soon takes the temperature of that 
 ground, through the agency of these terrestrial energy waves, 
 transformed by absorption and subsequent radiation from the 
 earth. .\n atmosphere thus serves to prevent such sudden and 
 extreme changes of temperature as are continually occurring on 
 the surface of the moon. 
 
 Glass readily transmits solar energy, and is nearly cpaque to ter- 
 restrial energy. Advantage is taken of this in warming greenhouses, 
 where tropical plants are thus made to grow under glass roofs. 
 
 The total euergj' that reaches the outer limit of om- atmosphere from 
 the sun is estimated to be sufficieot to melt annually an ice-shell 180 feet 
 thick over the entire surface of the earth. The absorptive power of the 
 atmosphere is equivalent to that of more than one-third of tliLs shell. 
 Keeping the earth's surface warm, it is continually radiating the excess 
 of heat back into space at all times, and thus preserving a nearly fixed 
 balance. 
 
 Effect of Aqueous Vapor on Radiation. — The atmos- 
 phere always contains a \'ariable amount of vapor, even when no 
 clouds are visible. This is a strong absorbent of solar radiation, 
 of all wave-lengths, and still more of terrestrial radiation. The 
 warmer the air is, the gi'eater is its capacity for carrying invisible 
 vapor, and the greater is its absorbent power for heat. A layer 
 of air thus charged may serve as a screen, and make the atmos- 
 phere disagreeably warm. The effect is increased when clouds 
 are present. But when the air is dry and clear, as at night, radia- 
 tion goes on rapidly and the temperature falls. 
 
 Distribution of Acpieous Vapor according to Ele- 
 vation. — With increase of elevation the air becomes colder, and. 
 its power of holding aqueous vapor diminishes. It has been calcu- 
 lated that one-half the quantity of vapor in the air is contained in 
 the lowest 6,000 feet of the atmosphere ; that above 20,000 feet 
 the amount is only one-tenth of that at the surface, and that for the 
 atmosphere as a whole the average quantity per cubic foot is only 
 about one- fourth of what it is at sea level. 
 
 If the air were perfectly dry, the rate at which the temperatm-e would 
 fall with increase of elevation would be 1° F. for every 180 feet at the 
 Equator, diminishing as we approach the poles, and also as we ascend. 
 But owing to the moisture in the air, the rate is only about 1° F. for every 
 .300 feet near sea-level. It gradually diminishes as we ascend, and ap- 
 proaches the ideal limit of perfect dryness. This fact has been ascer- 
 tained by observation in balloons and in the ascent of lofty mountains. 
 
 In any given latitude, therefore, climate must vary with the in 
 fluences that affect the ab.sorbent power of the atmosphere for heat. 
 The rnost important of these influences is elevation. Variation in 
 
64 
 
 ISOTHERMS AND CLIMATIC REALMS. 
 
 latitude also produces variation in climate, so that in traveling a few 
 thousand miles away from the equator there is as great lowering of 
 temperature as in ascending vertically a few miles at the equator. 
 
 Influence of Latitude. — The warming effect of radiation 
 from the sun upon the groimd and the air in contact with it, is 
 greatest in tropical and least in polar regions. This is due to 
 several causes. To explain it, let the shaded ring in the ligure 
 represent the earth's atmosphere, densest next to the ground ; and 
 let S E and S' N be equal bundles of rays from the sun, S E reach- 
 ing the earth at the Equator and S' N near the North Pole. 
 
 I. When the noonday sun is vertically overhead at E, the rays pass through 
 the least thickness of air, c a. Nearly two-thirds of the solar energy is there- 
 fore transmitted to the surface at a i. When the rays fall obliquely, a much 
 longer column of air, g i, has to be traversed, less energy can be transmitted 
 to the surface, g h, and more is absorbed in the upper regions to be radiated 
 back into space without warming the ground. 
 
 II. The effect of a wave of any kind is greatest when it strikes vertically. 
 This is familiarly seen in the action of water-waves. The solar energy waves 
 strike vertically after transmission at a J. Those which escape absorption at 
 g h strike obliquely, and hence with greatly diminished effect. 
 
 in. The area crossed by the line g h is greater than that crossed by 
 a J in proportion to the difference of latitude ; ii g h he three times a i, the 
 corresponding area is three times as great. The same amount of solar 
 energy can therefore have only one-third as much effect, even if there were 
 no loss due to obliquity of direction and increased absorption in the upper 
 layers. 
 
 Since the selective absorption is greatest for the short waves, the loss of 
 light in the polar regions is perhaps as conspicuous as the loss of heat. During 
 much of the year, there is nearly continuous twilight. 
 
 Variation of Temperatu^re in the same Latitude. 
 
 — Since the direction of the noonday sun is more nearly vertical in 
 summer than in winter, all the causes just described tend to make 
 summer the season of greatest hght and heat. But, in addition, we 
 have longer days and shorter nights in summer. The amount of 
 solar energy received during the long days is in excess of what can 
 be radiated back during the short nights. It becomes stored up in 
 the air and in the ground, so that the second half of the day, as 
 well as that of summer, is warmer than the first. 
 
 The warmest part of the day is usually between two and three 
 o'clock in the afternoon, the coldest is in the morning before dawn. 
 The warmest month of the year is July or August, though the sun 
 Is most nearly vertical at noon on the 21st of June. 
 
 Contrast of Low and High Latitudes. — At the Equa- 
 tor, the days and nights are of equal length throughout the year. 
 Absorption and radiation are therefore neai-ly balanced. In June 
 and December, the noonday smi is farthest from the zenith ; in 
 March and September, it is at or nearest the zenith. The climate 
 is uniformly warm, with little difference in temperature between 
 night and day. There are two summers, and two very mild 
 winters, June and December being winter months. Generally, in 
 low latitudes there is perpetual summer weather, with brief inter- 
 vals of less fervid warmth. 
 
 As the latitude increases, the length of the longest day increases. At 
 New Orleans it is fourteen hours ; at New York, fifteen hours ; at St. 
 Petersburg, nearly nineteen hours ; at Hammerfest, between two and 
 three months. The continued effect of nineteen hours of sunshine, even 
 though the rays are oblique, is to make the afternoons almost tropically 
 warm during a few weeks of the year at St. Petersburg, the short nights 
 affording little opportunity for loss of heat by radiation. But the 
 greater part of the year is cold. Generally, in high latitudes, the ex- 
 tremes of temperature are great, the winters being long and severe, the 
 summers short and uncomfortably warm. 
 
 Modifying Influences. — Important as latitude is in deter- 
 mining climate, there are many influences, both local and general, 
 that cause wide climatic differences in the same latitude. Were it 
 not for these, parallels of latitude on the earth's sm'face might also 
 be called parallels of climate. 
 
 Isotherms. — A line connecting a series of places whose mean 
 temperature is the same is called an Isotherm. If this mean tem- 
 perature is for the whole year, it is called an annual isothenn ; if 
 for some particular month, it is named accordingly, such as the 
 July or January isotherm. 
 
 The July isotherm of 70° is an irregular line, crossing North Amer- 
 ica, for the most part north of the United States. Talring then a direc- 
 tion slightly south of east, it arrives at Portugal and bends northeast- 
 ward, reaching the neighborhood of Lake Baikal, in Siberia, where the 
 mean annual temperature is only 30°. Deflected southward before 
 reaching the Pacific, it passes over more than half of this ocean about 
 the latitude of Japan, then bends down to the Tropic of Cancer before 
 turning northward to cross America. 
 
 The January isotherm of 70° passes south of the United States, cuiwes 
 in crossing the Atlantic, traverses northern Africa and the southern part 
 of Asia, and then crosses the Pacific in the neighborhood of the Tropic 
 of Cancer. 
 
 An isothermal chart thus enables us to form a general idea of the 
 climate of all regions embraced in it. By comparing the July and Janu- 
 ary isotherms, the annual range of temperature at each place is approxi- 
 mately learned. 
 
 Climatic Realms. — As the earth's surface is divided into 
 geographical zones by definite parallels of latitude, so it may be 
 separated into climatic realms by definite annual isotherms. 
 
 The torrid realm is that part on both sides of the Equator included 
 between the annual isotherms of 70°. Its northern limit is almost 
 wholly north of the Tropic of Cancer. Its southern limit crosses and 
 recrosses the Tropic of Capricorn. There is no climatic equator, but 
 within this realm are several areas of special warmth. Thus, over a 
 large part of north Africa, the mean annual temperature is believed to 
 exceed 85°. 
 
 The temperate realms are included between the annual isotherms of 
 70° and 30°, on each side of the Equator. In the northern hemisphere 
 the isotherm of 30° is for the most part south of the Arctic Circle, but 
 crosses this in Greenland and Lapland. In the southern hemisphere its 
 course is entirely over the sea, and is supposed to coincide nearly with 
 a parallel of latitude about 500 miles north of the Antarctic Cu-cle. 
 Within these two realms are the conditions best suited to human com 
 fort and civilization. 
 
MODIFICATIONS OF CLIMATE. 
 
 C5 
 
 The Arctic realm includes all that northern area whose mean tem- 
 perature is lower than 30°. The Antarctic realm includes the corre- 
 sponding southern area. 
 
 Within the Arctic realm in Siberia lies Werchojansk, a place where 
 the lowest temperature recorded has been —89°. Yet here the summer 
 heat has spv(>ral times reached -(-96°, making an extreme range of 185°. 
 In the American Aa-ctic regions there are places where the mean tem- 
 peratiu-e is as low as — 10°, and even in July rises hardly above the 
 melting-poLut of ice. 
 
 The human body is thus shown to be capable of enduring seasonal 
 changes of temperature about a.s great as the ditfereuce between the 
 freezing and boiling points of water. 
 
 Influence of Land-Masses.— Since the warmth of the 
 air depends chiefly on tliat of the siu-face upon which it rests, the 
 annual range a.s well as the mean temperature is greatly affected 
 by the nature of the surface medium that absorbs the sol;ir rays. 
 The effect of the sun in prodncing a Iiigh temperature is great- 
 est on dry sand and least on water. To raise the temperature of 
 a pound of sand through one degree requires only a fifth as much 
 heat as to do the same for water. On the surface of such soil 
 near the Cape of Good Hope, a temperature of 159° has been 
 recorded by Herschel. Air in contact with it becomes rapidly 
 heated and exceedingly di'v. 
 
 Clay, particularly when moist, is warmed far less rapidly than 
 sand ; but any land-mass whatever becomes heated and cooled much 
 faster than an equal body of water. Independently of elevation, 
 therefore, the center of a continent becomes warmer during the 
 day and colder at night than its shores. Its air is drier, its winter 
 more severe, and its summer heat more intense. 
 
 EXTREM: IN 
 SUMMER. 
 
 EXTREME IN 
 WINTER. 
 
 TEMPERATUnE-CtTRTES FOR THE FORTY-PIEST PARALLEL IN NORTH AMERICA. 
 
 These curves have been constructed from data afforded by the temperature maps 
 prepared for the Tenth United States Census by Mr. Henry Gannett. 
 
 The influence of a large body of land in thus producing extremes of 
 air-temperature is shown in the accompanying curves, which give the 
 mean and extreme temperatures observed along the 41st parallel of latitude 
 in the United States, extending from Long Island to the northern coast of 
 California. The figures at the top give the longitude from Greenwich, 
 those at tbe sides the temperature. By following these curves, it will be 
 seen that at the California coast on the 41st parallel the mean tempera- 
 ture is 55°, and the extreme range is only from 71° in summer down to 
 
 28° in winter. On going eastward, there is at once a marked increase in 
 range, so that at longitude ll.")", passing through tlie lofty desert west 
 of Great Salt Lake, the range is from 110" in summer down to — 30° in 
 winter. Tlio additional effect of elevation is shown at longitude 10(5° in 
 the Kocky Moiujtaius, where the highest temperature is 90°, the lowest 
 —50°, and the annual mean 34°. 
 
 The curve of mean temperature rises and sinks alternately until it 
 reaches the Atlantic, where it marks about the same (55°) as on tho 
 Pacific coast. 
 
 Effect on Mean Tempeiatiu-e of the Whole Earth. 
 
 —In the isothermal chart (jjp. 66, 67) the heavy lines indicate iso- 
 therms due to actual observation ; the dotted lines aie eontimiations 
 due to inference only, because of the lack of definite records. On 
 this chart the following general features may be noticed : 
 
 1. The isotherms are more irregular in the northern than in the 
 southern hemisphere. 
 
 2. The temperature of the earth's surface north of the Equator 
 is apparently higher than it is south of the Equator. 
 
 Both of these peculiarities are due to the position of the great con- 
 tinental land-masses. The northern hemisphere includes much more 
 laud than the southern. Its mean temperature becomes higher in sum- 
 mer and lower in winter, and it comprises more than half of the torrid 
 climatic realm. On this account the accumulation of heat on land causes 
 the mean temperature of the globe to be about 63.5° in July and only 
 54.5° in January, although the total heat received from the sun on the 
 two hemispheres is equal. In connection with this result it may be 
 observed that the earth's orbit is not circular but elliptic, and that in 
 January, which is the midsummer month foi- tho southern hemisphere, 
 the earth is 3,000,000 miles nearer to the suu than in Jul3'. 
 
 Influence of Ocean-Cnrrents and Winds. — Ocean- 
 currents have already been mentioned as the great distributors of 
 temperature. 
 
 The Gulf Stream cames in its surface-waters the heat poured 
 into it in tropical regions ; it distributes this over the I^orth At- 
 lantic and far into the Ai-ctic Ocean. The isothei-ms, in crossing 
 the Atlantic, therefore bend toward the northeast. That of 30° 
 passes near the mouth of the St. Lawrence, no farther north than 
 Loudon, and then extends over Greenland and the ocean to the 
 north of Hammerfest, far within the Arctic Circle. 
 
 The Japan CmTcnt causes the isotherms in the Pacific Ocean 
 to curve toward the north ; but, having a much wider sweep than 
 the Gulf Stream, its effects are not so marked. Its waters be- 
 come moderately cool in the neighborhood of Bering Sea, and 
 in completing their circuit they cause the isotherms to bend 
 slightly southward near the western coast of North America. 
 The temperature is still warm enough to give this coast a tmi- 
 forinly mild climate. It is densely wooded, and even bright w.'tli 
 verdure. 
 
 The Chief Conditions in determining the climate of a 
 
 place may be briefly summed up as follows : 
 
 I. If close to the sea, its climate will be uniform, and warm or cool, 
 according to the temperature of the nearest ocean -currents and direction 
 of the prevailing winds. This may be called oceanic climate. The Ber- 
 mudas are perpetually warm, Chile is perpetually cool. 
 
 II. If far from the sea, its climate will be dry, and sub.iect to e;:trenies 
 of heat and cold. This may be called continental climate. Moscow, in 
 Russia, and Santa Fe, in New Mexico, possess such a climate. 
 
 III. High elevation above sea-level and great distance from the 
 Equator alike tend to produce extremes of temperature, with preponder- 
 ance of cold or warm weather according to the latitude of the place. 
 The Sahara Desert, with a mean elevation of about 1,500 feet, is intensely 
 dry and warm by day, and uncomfortably cold at night: as is also Wer- 
 chojansk, in Siberia, with an annual range exceeding 150° F. 
 
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 Zf W ^HAvVft 
 
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 2 '*»' PHOENIX 16. 
 
 :.,WEST 
 
 ,so- 
 
 ^. 
 
 J 
 
 -•yi 
 
 ARCTIC CIRCLi 
 
 /^ 
 
 ^ 
 
 BopdPa, 
 
 ■TROPIC OF CANCER 
 
 'Oj/ '; ' 
 
 centraE^. 
 
 C> 
 
 GALAPAGOS IS. 
 
 103 iongitude West 73 from Washington 43 
 
 is EQUATOR 
 
 Below 0°, White and Brown, 
 Between o°and 3o°, Blue. ] 
 
 K' 30° " 70°, Green. 
 Above 70 , T'ivJc. 
 
 
 equatorO- 
 
 ■■OF/-i/-CAPRICOr(N 
 
 ISOTHERMS FOR WINTER (JANUAEY) 
 
 to: 
 
 0^=^^^ 
 ^^f^^, 
 
 
 EQUATOR 
 
 \ 
 
 ■76? 
 
 CPlC OFCAPRICORN' 
 
 >2, 
 
 .# 
 
 ISOTHERMS FOR SUM5[ER (JliTt 
 
 O 
 
 CAPE VERDE IS. 
 
 ^ 
 
 o.. 
 
 0) 
 
 Freetowu 
 aiuurovii^ 
 
 n- 
 
 ■ 0- 
 
 ASCENSION I. 
 73° 
 
 TROPIC ■OFCAPRICORN 
 
 .^0' 
 
 -60- 
 
 > 
 
 TRISTAN D'ACUNI 
 
 ^ 
 
 c 
 
 13 West East 17 
 
 Longitude 
 
 i7 from Wasliington 
 
 Questions on the Isothermal Map. — In what part of the worli 
 
 the north-temperate reahn widest '? Why is this so '>. Where is it narrowest ? Al 
 so? Trace the annual isotherm of 70° south around the world. What causes 
 sharp curve about the western part of South America ? Why should it bend southw 
 over the same continent ? Why should it bend northward near the African coii 
 What can you assign as a cause for its irregularities about Australia ? Compare 
 annual isotherms of 40°, north and south, tracing each around the world. Why is 1 
 of 40° south so nearly regular ? l7oes it cross any land ? Can you discover wlia 
 the relation between the bending of the annual isotherm of 40° along the Nor 
 coast and the nearest waters ? The mountain-ranges ? Do you note any connec 
 with the prevailing winds? [Consult Map of Wind-Zones, pp. 72, 73.) 
 
J80 West 
 
 lOWING THE MEAN ANNUAL TEMPERATURE OF THE ^IR 
 
 IN DEGREES OF FAHRENHEIT'S SCALE. 
 S(iTK—Thc}tt:aviifi{;un'^oiiVicLiiti:sUuiic<itcthciU:^jri:isiilomi ihc Litit^. The numlicr in Italic fiuuns n^Uh 
 
 iiamr of a city given itti Mean Temperature fi>r Januarii ; the number in Boman figures gives its Mean Trmpern- 
 ■fiirjulj/. ■ 
 
 133 Lonpitude from 103 AVjusliiufrton 
 
 'liat do you tliiuU can be the cause of the bend of the isotherm of 30° around 
 id y Coiii|iaie the mean annual temperature of Lake liaikal with that of Dublin. 
 
 e tlieir latitudes. Trace the annual isotherm of 70" nortli around the world. 
 
 are its most remarkable bends ? Can you account for these ? Trace the July 
 
 11 id' 70' north around the world. Why does it extend so much farther north 
 
 d than over the seaV Trace the January isotherm of 70° north around the 
 
 Tlie same, for the January isotherm of a0° north. Where does this last pass 
 
 ili;it are overlapped in summer by that of 70"? What kind of climate must 
 
 tliese places have? Trace the July i.sothcrm of 70° south around the world. 
 
 ' fame for the January isotherm of 70 south. In what month docs tliis show 
 
 '.ia to be warmest V Is any part of Australia thus shown to be perpetually torrid? 
 
 Name those parts of the Eastern Hemisphere wliose mean annual temperature ex- 
 ceeds 85°; 8H° ; 80'. Mention the parts of America whose mean annual temperature 
 exceeds 80' ; those portions of the world whose January temperature is below 0'. What 
 parts of these regions have a summer temperature exceeding 7o° ? \\'hat jilaces have a 
 mean annual temperature below 0° ? Give the winter and summer temperatures of 
 New Orleans, Santa Fe, New York, Chicago, San Francisco, Quebec, Reykiavik, Moscow, 
 Para, Honolulu, St. Johns, Bergen. Why the difference between St. Johns and Rey- 
 kiavik? Moscow and Bergen? Irkutsk and Berlin ? Honolulu and Mexico ? Yakutsk 
 and Reykiavik ? Which of the last two is fartlier north ? In what climatic realm is 
 New York ? Boston ? Charleston ? Havana ? London ? Paris ? Berlin ? Rome ? Cal- 
 cutta ? Melbourne ? Rio Janeiro ? Cape Town ? Stockholm ? Reykiavik ? Khartoum ? 
 
68 
 
 THE WINDS.— ISOBARS. 
 
 IV. The range of temperature is less 
 in the southern than in the northern 
 hemisphere, which contains hirger bodies 
 of land extending into the polar regions. 
 In the southern parts of South America, 
 Africa, and Australia, the diiference be- 
 tween the mean temperatures of July and 
 January does not mvich exceed 20°. Over 
 a large part of North America and Eura- 
 sia, it exceeds 60°. 
 
 THE WIJfDS. 
 
 Currents of the Atmospheric 
 Ocean. — We have already seen {p. 
 69) tliat in any fluid surrounding the 
 eai-th, currents are necessarily produced 
 if the Ecpator be warmer than the 
 poles. The air is a fluid much lighter 
 than water and more easily set in mo- 
 tion. The currents in it are called 
 Winds. 
 
 In the aqueous ocean we ordinarily 
 perceive only those currents which flow 
 at the top ; in the atmospheric ocean, 
 those which circulate at the bottom. 
 
 Winds are named according to the direction from which they 
 come. An east or easterly wind blows from east to west. 
 
 Cause of Wind. — When air is heated by contact with warm 
 earth or warm water, its density is decreased by expansion. The 
 lower layers in expanding tend to lift up those which rest upon 
 them, and produce an outflow in all directions at the top. Pressure 
 being thus diminished, the lighter warm au- is pushed upwai'd by 
 the inflow of the surrounding denser air at the surface. 
 
 The pressure of the air being measured by the height of the barome- 
 ter {compare p. 63), it follows that, at the surface of the earth, wind 
 
 January Isobars and Pkevailing Winds. 
 Tho dotted lines indicate pressures above 30 inches. The heavy lines indicate pressures below 30 inches. 
 
 July Isobars and Prevailing Winds. 
 The dotted lines indicate pressures above 30 inches. The heavy lines indicate pressures below 30 inches. 
 
 must generally bloiv from a region where the barometer is high toward 
 a region ivhere the barometer is low. 
 
 Isohars. — Aside from local variation of pressure, the height of 
 the barometer is influenced by variation of gravity, ^vhose standard 
 value is that at latitude 45° ; by the temperature of the instrument ; 
 and by elevation above sea-level. Observations are therefore cor- 
 rected so that all records may be compared according to a single 
 standard. The results are called reduced observations. 
 
 Isobars are lines connecting places where the reduced height of 
 the barometer is the same at the same time. 
 
 Thus, in the opposite map, the isobar 
 of 30.4 inches is a closed curve over Asia, 
 within which is an area of high press- 
 ure. Wind flows at the surface in all direc- 
 tions away/rojw this. The isobar of 29.4 
 inches is a closed curve over the North At- 
 lantic Ocean, within which ls an area of 
 low pressure. Wind flows at the surface 
 in all directions toward this. 
 
 General 3Iotions of the At- 
 mosphere. — If the eai-th were entire- 
 ly covered with water, uniformly heated 
 at the Equator, and cooled at the poles, 
 there would be a continual uprising of 
 warm and moist air in the region of 
 greatest heat, which would also become 
 a region of low density. On both sides 
 of this warm belt, there would be in the 
 upper atmosphere an outflow toward 
 the poles, and next the sm'face an in- 
 flow from the poles. 
 
 If the earth were not rotating, the 
 direction of the upper and lower cur- 
 rents thus produced would be due north 
 and south. Where the motion of the 
 air is upward, no breeze would be felt. 
 
INFLTENCE OF CENTRIFUGAL FO RCE. — FE R R E L'S LAW. 
 
 69 
 
 But since tlie earth rotates, air-cTin-ents as well as ocean-currents 
 are turned away from their first direction {nee p. 59). The east- 
 ward velocity of rotiition at the Equator is over one thousand miles 
 an hmir, and diiuinislies with approach toward the poles. Currents 
 of air, flowing over the surface from the slow-moving middle lati- 
 tudes to the swift-moving equatorial zone can not at once assume 
 the increased velocity of this region. 
 
 Over a belt north of the Equator, tlie wind must heuce blow from 
 the nortlieast ; soutli of it, from the southeast ; on botli sides, becoming 
 nearly oast when close to the Equator. 
 
 In like manner, the outHowiug upper currents, passing to the slow- 
 moving middle latitudes, can not at once give up their eastward velocity. 
 Cooled by their ascent, they gradually sink until they begin to sweep 
 over the siu-face just beyond the tropics, as winds from the southwest in 
 the northern hemisphere, and from the northwest in the southern. 
 
 Thus, whatever be the latitude, a j^ei'son traveling irith the ivind 
 either from north or .south would be graduaUy tuniiny ton-ard his 
 right in the northern and toward his left in the southern hemisphere. 
 
 Influence of Centrifugal Force on the Atmosphere. 
 
 — Let a body, held by a string, o a, be swung around once a sec- 
 ond on an axis, o. If released at 
 «, it flies off in the direction a h. 
 The tendency to fly ofE is called 
 centrifuyal force. If the string be 
 lengtlicncd while the body is still 
 revolving once a second, the force 
 is increased. If the body be swung 
 faster, the force is additionally in- 
 creased. Hence, on a rotating 
 sphei'e, centrifugal force is great- 
 est at the Equator. If the rate 
 of rotatioTi be decreased, a body 
 
 on its surface tends to move f)'0)ii the Equator ; if increased, 
 
 toward the Equator. 
 
 Since the earth rotates rapidly toinard the east while the direction 
 of the wind near the Equator is from the east, the centrifugal force act- 
 ing on tlie air is slightly cheeked. The air, therefore, tends to flow 
 away /roHi the Equator toward the middle latitudes where the distance 
 from the earth's axis Ls less. 
 
 In like manner, since the earth rotates toward the east, and the di- 
 rection of the wind in middle latitudes is also toward the northeast in 
 the northern hemisphere and toward the southeast in the southern hemi- 
 sphere, the centrifugal force acting on the air is slightly increased. The 
 air, therefore, tends to flow away from the middle latitudes toward the 
 Equator where the distance from the earth's axis is greater. 
 
 Thus, whatever be the latitude, a person traveling with the wind 
 either from east or west would be gradually turning toward his right 
 in the northern and toward his left in tlie southern hemisphere. 
 
 Ferrel's Law. — Taking all these motions into consideration, 
 we may now state the law generally, that " in whatever direction a 
 body moves on the surface of the earth, there is a force arising 
 from the earth's rotation which defects if to the right in. the north- 
 ern hemisphere hut toward the left in the ■southern.''^ 
 
 This law was first applied to the atmosphere by Professor William 
 Ferrel, and published by him in June, 1859. It applies to all bodies 
 moving on the earth, whether solid or fluid. 
 
 Exactly at the Equator, where the velocity of rotation is greatest, 
 there can be no deflecting force. This begins to be manifested on either 
 side of the Equator, and becomes greater as we move to higher latitudes. 
 
 Since by Fei-rel's Law the air tends to move away from the Equator 
 and also from the middle latitudes, there must be in each hemisphere a 
 belt where it is piled u)) and thus made denser. This belt is where the 
 eastward and westward tendencies due to the earth's rotation just bal- 
 ance each other. Referring to the isobars on page 68, we shall see that 
 
 the mean pressure in January over the Atlantic Ocean is 29.8 inches 
 near tlie Ecjuator, 150.2 inches near the Tropic of Cancer, and 29.4 inches 
 about latitude 00" ntnth. Near the Troi)ic of Capricorn it is again over 
 thirty inches, and it diminishes toward the Antarctic Ocean. 
 
 Again, since centrifugal force tends to make the air recede from the 
 poles toward the tropics, the atmospheric ocean should be thinnest at the 
 polar regions, and these should be regions of low pressure. This fact is 
 shown by the isobaits on page 68. A cold wind blows outward from the 
 polar regions, due to centrifugal force, and not as elsewhere to excess of 
 pressure. New supjilies of air are furnished continually at the i)olcs by 
 upper currents from equatorial regions. 
 
 Ilhistration of Ferrel's Law. — All the chief constant 
 motions of the atniosphere are shown in the figure below. Surface- 
 currents flow from the tropics toward the Equator and then rise, 
 leaving below an eqtiatorial zone of calms and low pressure, toward 
 which wind constantly blows obliquely. Of the outflowing upper 
 current, pai-t .sinks to the surface near each tropic, and then divides, 
 s(mie going back to the Equator and some sweeping onward. Here, 
 then, are the tropical zones of calms and high, \^ressxire,from which 
 the wind blows toward both Equator and pole. 
 
 The rest of 
 the upper cur- 
 rent continues 
 toward the pole, 
 where it sinks 
 and then flows 
 outwai-dasacold 
 surface-cuiTent. 
 Here, therefore, 
 are the polar 
 zones of calms 
 and loiv pres:,- 
 ure, from which 
 the wind blows 
 outward in all 
 directions. In 
 the neighbor- 
 hood of latitude 
 60° this cold cur- 
 rent meets the 
 warmer surface- 
 current from the 
 tropics, produc- 
 ing an area of variable winds, according as the one or the other pre- 
 dominates. Part of it is forced upward, and flows as an intermediate 
 cold current toward the tropics. All these currents are deflected accord- 
 ing to Ferrel's Law. 
 
 ftuestions. — Of what does meteorology treat ? State the composition of air. 
 To what height does the air extend ? What pressure does it exert ? Ex- 
 plain the principle of the barometer ; the diminution in the density and 
 pressm-e of the air with increase of height. 
 Define climate. What are the principal elements of climate ? Explain solar 
 energy; the difference between heat-producing and light- producing rays 
 of solar energy. What proportion of light-rays are absorbed by the atmos- 
 phere at different times of day ? What can you say of the absorption of 
 solar energy by different substances ? Why is the sky blue ? On what 
 does the temperature of a place depend ? How does elevation affect tem- 
 perature ? How, the air's power of holding moisture ? 
 Discuss the influence of latitude on climate, and the variation of temperature 
 in the same latitude. What is the warmest part of the day ? the coldest ? 
 Why ? What are isothermal lines ? Into how many climatic realms may 
 the earth's surface be divided by isothermal lines ? Explain the influence 
 of land-masses in modifying air-temperature; the general influence oi 
 ocean-currents and winds. In which hemisphere are the isothermal lines 
 more irregular ? Specify the conditions determining the climate of a place. 
 How are winds produced ? Explain the circulation of the atmosphere. Wliat 
 are isobars ? Explain the influence of centrifugal force on the atmos- 
 phere. State and illustrate Ferrel's Law. 
 
 Illlstk.iting Fekuel's Law. 
 
70 
 
 WIND-ZONES AND CALM-BELTS. 
 
 COMSTAJfT AJfD PERIODICAL WIJVDS. 
 
 Wind-Zoues. — The earth's atmosphere may be divided into 
 wind-zoues. Their limits are not fixed, for several reasons : 
 
 1. The heating of equatorial regions and the cooling of polar 
 regions is not imiform, because of the great laud-masses on which 
 changes of tempera tm'e occur more rapidly tliau on the ocean. 
 
 2. Mountain -ranges interrupt the surface-winds and produce 
 irregularities. It is only on the sea, where there is a free sweep, 
 that constant winds are possible. 
 
 3. The belt of greatest heat changes its position with the sea- 
 sons, moving farthest north in August and farthest south in Feb- 
 ruary or March. The position of the wind-zones varies accordingly. 
 
 The Calms of the Equatorial Zone occur in a belt 
 mostly north of the Equator. On the Pacific it covers the Equator 
 in January, and is entirely north of it in July. {Compare the maps 
 on pp. 66, 73.) The breadth varies from 1° to 6° in latitude, 
 being greatest in the eastern part of each ocean, near the great 
 continents which disturb, the regularity of the winds. 
 
 lu this zone the calms are not constant, nor do they occur in all 
 parts of it, but only in isolated regions. 
 
 The Trade- Winds are constant winds on either side of the 
 equatorial zone. Each belt •occupies from 12° to 25° of latitude, 
 begiuTiing some distance west of the interrnpting continent. The 
 wind starts as a gentle breeze from the northeast or southeast, in- 
 creasing in strength and becoming almost a due east wind along 
 the equatorial margin of the belt. In the Indian Ocean, it is 
 constant thi'oughout the year only in the southern belt, being in- 
 terrupted on the north by Asia. 
 
 The constancy of the trade- winds has been known since the time of 
 Magellan. Their name was given on accomit of their importance in 
 facilitating commerce across the oceans. 
 
 The Calm-Belts of the North and South Temper- 
 ate Zones are uai-row and not well defined. They are distiu-bed 
 by storms and rapid alternations of wind, due to encroachment 
 from the neighboring wind-zones. 
 
 The Anti-Trade Winds are limited by the tropical calm- 
 belts and extend towai'd the poles into tlie region of Arctic and 
 variable winds. The conflict of the polar winds causes variability 
 over the greater part of this wind-zone, but the prevailing winds, 
 especially over the oceans, are such as mig-ht be expected according 
 to Ferrel's Law. In the southern portions of the Pacific and In- 
 dian Oceans, between latitudes 40° and 50°, they blow so steadily 
 and strongly as to receive the name of " Roaring Forties." En- 
 croaching upon the Antarctic Ocean drift, they cause this great 
 current of water to flow permanently northeastward at the surface. 
 [See JordaiTbH ^^The Winds and their Stoi^y of the World" pp>. 
 38, 4B.) 
 
 The Polar Winds.— Along the Arctic shores of North 
 
 America and Asia, these winds blow quite constantly over the laud, 
 
 ■ during most of the year, as dry and piercing cold blasts from the 
 
 northeast. The Antarctic polar winds, so far as known, blow from 
 
 the southeast. 
 
 It should be noted that, although the pole is a region of low pressure, 
 this is not due to any special lack of density in the air at the surface, but 
 to deficiency in the height of the atmosphere. The colder and drier the 
 air is, the greater is its density. When the cold polar wind penetrates 
 southward, it produces an immediate rise of the barometer by flowing 
 under the lig-hter warm au', lifting this up, and adding its own weight 
 to that of the elevated portion until the latter can flow away. 
 
 Wind-Zones on Land.— In certain parts of the torrid 
 zone, where wide areas are but little interrupted by mountain- 
 ranges, the trade- winds are perceptible on the land as well as on 
 the sea. This is true of the v.alley of the Amazon, which is con- 
 tinually swept by moist winds from the east, bringing abundant 
 rains that feed the great rivers of South America. Over the Sa- 
 hara Desert in Africa, winds of withering dryness and warmth 
 blow with much steadiness from the east and northeast. 
 
 Irregularities in Wind-Zones. — In the northern hemi- 
 sphere, great modifications are produced by ocean-currents as well 
 as land-masses. On the map of January isobars, it will be noticed 
 that t;he region of low pressure on the Atlantic and Pacific Oceans 
 extends down to latitude 40°, while that of high pressure in 
 America and Asia reaches into the Arctic regions. The Gulf 
 Stream and the Japan Current carry warmth into the zone of anti- 
 trades, rarefying the atmosphei-e even more than would be due to 
 the general circulation of air. The interior regions of North 
 America and Asia become exceedingly cold by radiation in winter. 
 The atmosphere has a greater density than would be due to gen- 
 eral circulation. In winter, therefore, the general tendency is for 
 the wind to Mow from the land to the sea. 
 
 On the map of July isobars, the Atlantic and Pacific areas of 
 low pressure are shown to have I'etreated northward, and the con- 
 tinental masses, being much heated, to have become covered with 
 rarefied air. In summer, therefore, the general tendency is for 
 the wind to hlow from the sea to the land. 
 
 In the southern hemisphere the same truth prevails, but is not so 
 strikingly shown, on account of the smaller size of the bodies of land. 
 
 The Variable Winds. — The alternation due to conflict be- 
 tween the anti-trades and polarr winds is thus seen to be controlled 
 largely by the seasons. 
 
 In the northern hemisphere, during the summer, the southwest 
 anti-trades sweep over land and sea with moderate constancy almost 
 to the Arctic regions. They bring warmth and moisture with 
 them, but are modified locally by the relative position of masses of 
 land and water. " Warm waves " in summer usually come from 
 the southwest in this hemisphere. 
 
 In vrinter, the body of cold air in the Arctic regions grows 
 larger, and the polar winds, increasing in strength, sweep farther 
 south. In North America, they reach across the low plains around 
 Hudson Bay, and are spread over the region of the Great Lakes. 
 In the United States "cold waves" generally come from the north- 
 west, and are followed by clear, dry weather. In Europe and Asia, 
 they come from the northeast. 
 
 The transition from one prevailing wind to another in any place is 
 usually accompanied with a rain-storm. When the center of such a 
 storm in winter passes over the United States, cold air from the north- 
 west is drawn in and cold weather follows, lasting often a number of 
 days. 
 
 Periodical Winds. — In addition to the constant and varia- 
 able winds already discussed, there are some which alternate with 
 much i-egularity, reversing their direction each day or each year. 
 
 Land and Sea Breezes. — Ordinarily on the sea-sliore, 
 but especially in tropical countries dm'ing summer, whenever the 
 weather is clear and bright, a mo!-ning breeze sets in toward the 
 land, and subsides near sunset. This is called the sea-breeze. A 
 little before midnight, an opposite breeze springs up and continues 
 until sunrise. This is called the land-breeze. The interval be- 
 tween the two is often nearly or quite calm. 
 
THEORY OF STORMS, 
 
 71 
 
 Water becomes chang'ed in temperature very slowly (see p. 4^), while 
 tlie siu'face of the ground is heated or cooled rajjidly. On this account, 
 and also in consequence of evaporation and the vertical circulation due 
 to wind and waves, the surface of tlic sea is kept cooler by day than that 
 of tile land , but at lUKht, the land by its rapid radiation l)CConics cooler 
 than tlie sea. When the air in contact with the warm ground is heated, 
 it expands and lifts the ujiper layers, so that these slide off toward the 
 coolei- sea, producing an increase of pressin-e at first some distance from 
 tbe land, A breeze spreads along the sui'face ; and at the same time, 
 over the land, the removal of the upper layers causes a decrease of 
 pressure. The sea-breeze start.s in the ofling, so as to be felt at sea before 
 it it'aches the laiul. Arriving during the forenoon, it is strongest about 
 three o'clock i'. M. (See Blaiifoni's "Iiiclicm Meteoroloyiats' Vade 
 Meciim" part ii., § 7^.) 
 
 During the night, the air in contact with the land is rapidly cooled 
 and condenst'<l. Tluit from the ui)per layers over the sea flows in above, 
 producing an excess of pressure, so that a breeze stiirtsou tlie land and is 
 forced out to sea. It is strongest during the latter part of the night. 
 (Consult Scotfs '^Elementary Meteorology " p. 286.) 
 
 A similar explanation applies to the breeze that in warm countries 
 Hows from the valley or i)lain up the mountain-slope during the day, 
 reacliing its greatest strength in the afternoon, and reversing its direc- 
 tion during the uight. The mountains grow warm Ijy day and Ijecome 
 cool at night fa.ster tluin the valleys and low plains. Hence their rela- 
 tion to the plains is similar to tliat of a body of laud to the sea. But the 
 plain also becomes slowly warmed during the forenoon, causing the 
 upi)er laj'ers of air to flow off toward the cooler mountains, cai-rying 
 moisture which is condensed into clouds. These are usually nK)st abun- 
 dant around mountain-tops during the latter pai-t of the day. At night, 
 the conditions are reversed, causing the peaks to be most free from 
 clouds in the early morning. 
 
 The Monsoons. — In the tropical regions of the Eastern con- 
 tinent, wlieru the sun's heat becomes acciiiaulated on large hmd- 
 niasses, the sea-breeze ^jrevails tliroughout the summer and the 
 land-breeze tliroughout the winter, each blowing with much 
 strength and constancy. They are called Monsoons (sm-w/is), and 
 are strong enough in the northern ])art of the Indian Ocean to 
 modify the trade-winds, or even to overpower them. Over the 
 nrea between India and Africa the summer monsoon blows from 
 the si;)uthwest, the winter monsoon from the northeast. 
 
 The trade- wind belts, as has been already sho\\Ti, vary in position 
 with the season of the year. In the northern summer they reach far- 
 thest north, but require an open sea for their existence. The northeast 
 trades, therefore, do not blow to any great extent in summer over the 
 Asiatic and African Continents, but the southeast trade-belt extends even 
 to the north of the Equator. The heating of Asia south of the Hima- 
 layas produces so continuous an upward current of warm air over the 
 land that the southeast trades are deflected towai-d the north and east, 
 causing an uninterrupted sea-lsreeze mainly from the southwest, which 
 is laden with moisture and l)rings copious rains. 
 
 In the northern winter the trade-belts are shifted southward ; the 
 northeast ti'ades set in, and are intensified along the coast of Africa by the 
 heating of this continent. Crossing the Ecpiator, they become deflected 
 so as to produce the northwest monsoons on the coast of Australia. 
 
 The time of the " breaking up of the monsoons," just after the equi- 
 noxes, is mai'ked by frightful tempests. 
 
 Monsoon regions occur also in tropical America, but the winds 
 are not comparaljle to those of the Indian Ocean. 
 
 Local Winds. — Local names are given to winds that blow 
 with more or less regularity at certain seasons of the year. Such 
 are the Sirocco, from the Sahara to Sicily ; the Khamsin and the 
 Harmattan in Africa, all hot desert winds; the Mistral, the Bora, 
 the Purga, cold winds. The "Xorthei-s" of Texas sweep in win- 
 ter from the Rocky Mountain region sometimes entirely across 
 the fxulf of ]\Iexico. The general explanation already given ap- 
 plies to the local conditions that occasion these winds. 
 
 STORMS. 
 
 Definition. — Aside from the general circulation of the at- 
 mosphere, tliere arc disturbances in which the air pursues a more 
 or less spiral or whirling course for a limited time. Jvaiu or snow 
 usually falls, and when the commotion is violent it is accomjiauied 
 with lightning and thunder. The general name of Cyclone is 
 applied to all such whirling storms. 
 
 Classiflcrttion of Storms. — Storms may be classified ac- 
 cording to (1 ) their \'ironu\\{;iit features, as rain-, hail-, snow-, dust-, 
 wind-, or thunder-storms; {'!) the direction of the principal winds, 
 as northeasters, southeasters, etc. ; (3) the strength of the wind, as 
 gales, hurricanes, tornadoes, etc. 
 
 Local names are also applied, such a-s the toi'nado in the United 
 States; the hurricane, an extensive whirlwind of the Atlantic Ocean; 
 the typhoon of the Indian and Pacific Oceans. 
 
 The term lyclone should not Ije restricted to the tornado, as is too 
 frequently done in the United States. 
 
 Cause of fStornis. — AVe have seen how the influence of the 
 suunner sun on the laud or water may cau.se the lower layer of air 
 to expand and lift the upper layer like a great gaseous sheet. The 
 tendency is for the lifted gas to spread uniformly outward in all 
 directions, thus causing the heated ai'ca to become one of low 
 pressure and the surrounding area to have its pressure increased. 
 
 If for any reason, such as the ascent of air from a limited area 
 warmer than the rest, a local ciiimney can be forced through the upper 
 stratum, an up-rush is established by which warm and moist air is raised 
 and cooled by ex])ansion. The vapor it contains becomes condensed, 
 thus liberating as heat a large amount of energy which had previously 
 become stored up in the process of evaporation. This hi tm-n still 
 fui'ther rarefies the ascending current, so that the draught is 
 strengthened ; warm vapor-laden air flows in from all sides at the bot- 
 tom to supply the pai-tial vacuum, and to increase it b3' adding new vol- 
 umes of light vapor to be condensed into clouds. These spread outward 
 in the upper regions, and the central area becomes quickly one of low 
 pressure and rain. It is the starting-point of a storm. 
 
 Spiral Motion. — If the storm-center be in the northena 
 hemisphere, the lower air-currents, flowing in at first gently from 
 a distance on all sides, must lie deviated toward the right accord- 
 ing to Ferrel's Law. As the}' apjjroach the center they increase 
 in violence, and the storm area liecomes better defined. In con- 
 sequence of deviation, currents which would otherwise meet at 
 the center tend to rush past one another, and a whirling motion is 
 thus produced in a direction opposite to that of the hands of a 
 
 watch. In the southern hemi- 
 sphere, the deviation is toward 
 the left, and the whirling motion 
 is iu the same direction as that of 
 the hands of a watch. 
 
 As the circling currents are 
 drawn still nearer to the center, 
 the motion becomes spiral, as 
 shown iu the accompanying dia- 
 gram, and that on p. 75, the de- 
 viation according to Ferrel's Law 
 being now more than overcome 
 by suction into the great vortex. 
 Motion around any center develops centrifugal force, which tends 
 to rarefy the central area still more. Within this area the barome- 
 ter indicates very low pressure, and little or no wind is felt. 
 
 The central area of calm may be but a few yards in (hameter, as in 
 the tornado, or fifty miles or more, as iu hurricanes and typhoons. The 
 
 WJ^S^ 
 
Longitude 
 
 30 
 
 
 1) S O A Ip. K' ''■'„/ 
 
 H I 
 
 10 
 
 
 •4 ^•S 
 
 
 i 
 
 
 
 B 1 1 
 
 J 
 
 'b 
 
 «> 1 C e LA*N D 
 
 '^^ ^ R E ,V A 
 
 
 ■^ V'^ '•' , " - AZORES 
 
 J v£r's,,,';,,,,„,,iV /F"!'"'*"^ A^ L M S O F c A N C 
 ■^ ^ .U-Z^-l^ 4? ^'". ^ ' Sorse Zaiit„,d,„ 
 
 E B 
 
 ./' ./ 
 
 i^i 
 
 iALAPAGOS 
 
 WINDS 
 
 ■..Q. 
 
 i~i 
 
 -n f-^* — j- 
 
 Vaipai-aiso -^v ~ )^ 
 
 TaldRiȣ:J.f: 
 
 ^ 
 
 
 V^' ^ \ \ \ \ 
 
 s 
 
 < 
 
 o 
 
 / / 
 ^ il^ l^ ^ P ^^-R^-E V / 
 
 ^ "^->y , '.^^ FALKLAND ,S. 
 
 SOUTH GEOH 
 
 \ 
 
 X 
 
 \ 
 
 \ 
 
 o^- >' • ' " ' "^ ' "^ f G R E 
 
 ^. -*>' NORTH-EAST "'""" fe:^"'= 
 l^sLAt^Bs^ — ____;^> ' ■ ^ 
 
 i-.l>il;i EQUATOR ^ ^^ ci,, 
 
 PeinamTjucOJ < .^ \ \ ASCEt-5.01. ff 
 
 ^ ^fi^o U T h'-^e^'a s t 
 
 Longitude 
 
 In studying this map, or comparing it with the text, the student 
 should bear in mind the following important considerations : — 
 
 I. There are in reality no sharp lines of demarkation between 
 rain areas like those between the different colors on the map. Each 
 area grades insensibly into those which bound it. 
 
 II. The rain-zones mentioned in the text can not be properly 
 represented on a map, because their position is rariable according to 
 the season of the year. 
 
 III. The arrows represent the prevailing direction of the winds, 
 but these are also subject to much variation, due to local or tem- 
 porary causes. 
 
 Questions on the Map of "Wind and Rain 
 
 Zones. — In what regions are prevailing westerly winds ? Are 
 these winds due west ? When are they from the northwest ? When 
 from the southwest ? When alternately from southwest and north- 
 east ? Trace the usual track of hurricanes over the North Allan- 
 tie Ocean. Over the Indian Ocean. Over the North Pacific. Over 
 the South Pacific. Where do the following local winds occur, and 
 what is the character of each : the Harmattan ? the Khamsin ? the 
 Solano ? the Fohn ? the Mistral ? the Bora ? the Simoom '? Where 
 are the Horse Latitudes ? The Doldrums ? Where do you find calms 
 indicated on the Atlantic Ocean ? The Indian Ocean ? The Pacific ? 
 
 M'here do you find the 
 tumn, with the principal dr 
 the regions of winter rains, 
 you discover any connection 
 places and the prevalence of 
 the Atlantic from New Yor 
 helped or obstructed by the 
 returning from England to 
 and winter ? In what season 
 perience most rain ? What i 
 to rain in Florida ? Between 
 
PELEW 18. .' ■■ • ^ .. 
 
 
 ,NN' 
 
 fj , \ V GILBERT IS. ^ .. 
 
 ARpHl'gELAGO . / -^ •^^jT,* ' 
 
 SOLOMONVIS. \ ^ ■jl 
 
 ^ £, 
 
 
 NEW HEBRIDES 
 
 \ 
 
 .\... 
 
 — :.;=r-^| ^ — ^ h .: ■^. 
 
 ■ ■*' y: 
 
 '•\ 
 
 / 
 
 Q U ^ 
 
 A 
 
 
 •^ 
 
 N N- 
 
 M 
 
 \ 
 
 • ECJUATOR "■ ~ — ^s"'^ '■"~ ■ 
 
 GALAPAGofc IS. 
 
 'FRIENDLriS. 
 
 * COOK I 
 
 itROPIG OF CAPWCOSN 
 
 SOCIETY IS. «*■'*. 
 
 S 0. U.T H T E A S, T. 
 T R A b E - W I N D S 
 
 
 '•». .r^,.^ -tl 51 AucVTandiX, ^ 
 
 ' ' , ""^ --'---....».•< ' - •WellmgtoiK /'■' 
 
 — -4. -— — F^ "^. \ «, /^vA 
 
 C A 
 
 T^fy 
 
 / / 
 
 \ 
 \ 
 
 Y _ w 
 
 \ 
 
 o 
 
 N. 
 
 \ \ \ 
 
 . \ 
 
 _z_ 
 
 V"-*^-' 
 
 CO R M, 
 
 / / ^ \ 
 
 .r 
 
 Wiishington 
 
 ) he in summer and au- 
 1 inter and spring? Trace 
 
 1 rain in summer. Can 
 oecurrencc of rain at these 
 
 Cape Ilatteras and Newfoundland ? On the Great Plains west of the 
 Mississippi River ? In Mexico, Central America, and most of South 
 America? Along the coast of Peru? The southern half of Chile? 
 Why this contrast between Peru and Chile? What is the character 
 trade winds ? In crossing of the seasons in respect to raiu between Uudson Bay and Alaska ? 
 )1, would a steamship be In most of Siberia ? In most of Europe ? In Canada and the north- 
 nds? Hiiw would it be in ern part of the United States? Where are the Khasia Hills ? What 
 tliis true in both summer do you associate with them? Does this occur in summer or in 
 feliT on such a voyage ex- i winter '! Where is the region of typhoons ? What regions are nearly 
 M- of the seasons in respect ] rainless ? Are there any extensive rainless regions on the ocean ? 
 I Cape Ilatteras? Between j What is the mean annual rainfall at Pernambuco ? 
 
 CURRENTS OF THE AIR 
 
 AND THE 
 
 SEASONS OF RAINS. 
 
 EXPLANATION., 
 
 I \Normai Tropical Rainy Season (Summer and Autumn) irithaprinci- 
 
 I j jtal Dry Season in ifinter and Spring. 
 
 ~\ Transition Region, irith Rains in Siitnmer and Winter. 
 ~1 Winter Rains and scarcit y of Rain in Summer. 
 
 ~\Rain in Spring or earltj Summer with a Dry later S'xmmer, Ratn 
 imostly in Autumn or early Winter. 
 
 j "^AU months of the year regularly rainy or {snowy in Winter.) 
 
 Prevailing Winter Rains and yet the Summer regularli/ rainy (t; to l^f 
 days each month) 
 
 j[_ J Ea^hmonth of the year very rainy but principally the Winter ynonths. 
 
 I j Each month of the year rerylittte Rain, and some parts txfthis Region 
 
 I 1 are rainless. 
 
 ' The Regions within this Line have Dry Seasons respectively trith the 
 
 months irho^e mnmal fre<inenry of rain is less than .SO on; rainy 
 -.-.-. days in the month (I'eriodictil Ruins). 
 
 \- I Xo7-them Regions of Light Snow in Winter. 
 
 Note. The Xujnhtr under the \ame of a Place sftou-j ike annual 
 amount of Rain -fall in inches at that place. 
 
74 
 
 OYCLONIO STORMS, 
 
 wind blows spirally around it, with the greatest violence at its edges. 
 The ascending column, twisting around its upright axis, becomes spread 
 out spirally in the upi^er regions, so that around the cyclone the pressure 
 of .the air is a little greater than average, while at the center it is far less 
 than average. 
 
 On entering a cyclone area, therefore, the barometer first rises 
 sUghtly at the outer margin (a and 6, figure) and then falls rapidly, 
 reaching its lowest limit at the middle of the central area (c) under the 
 ;isceiiding vortex. 
 
 Motiou of the kind just described is called gyratory motion. 
 
 Gtkatort Motion. 
 
 This cut shows the upward and spiral course of the vapor-particles. In a great 
 cyclone there is no such sharp outline or rope-like appearance ; and probably' no one 
 particle makes a complete circuit, since the diameter of the column greatly exceeds its 
 height. 
 
 In the hurricane of Guadeloupe, September 6, 1865, the barometer 
 fell from 29.64 inches to 27.95 inches within seventy minutes. A fall of 
 two inches during the course of a cyclone is not uncommon. {See, 
 Biichan's ^^ Handy Booh,'" p. 266.) 
 
 The wind blows at a rate too high to be measured, but certainly 
 nearly or quite 100 miles an hour. It prostrates trees and houses, and 
 raises waves on the sea that overwhelm the largest ships. At the center 
 there is sometimes a warm area with clear sky, but around it the sky is 
 .covered with clouds so dense that day is almost turned into night. The 
 rain falls in sheet-like torrents which are di-iven nearly horizontally by 
 the wind and broken into blinding spray, so that large objects become 
 invisible at a distance of 50 or 100 feet. 
 
 The effect of a cyclone is most disastrous when it passes from sea to 
 land on a low, flat coast, at the period of high tide' Not only is the 
 water driven on shore by the wind, but the height of the tide is increased 
 by the partial withdrawal of atmospheric pressure at the storm-center. 
 Thus, in October, 1886, a town in Texas at the mouth of the Sabine River 
 was completely flooded and about one hundi-ed lives were lost. This 
 disaster was far surpassed in 1876 near the mouth of the Ganges. The 
 sea swept over the land to the height of forty-five feet, destroying more 
 than one hundred thousand human lives. (Consult Blanford^s " Vade 
 Mecum,'' p. S57.) 
 
 Starting-Places of Cyclones.— Since by Ferrel's Law tlie 
 deflecting force due to the earth's rotation is greatest in higli lati- 
 tudes and vanishes at the Equator, there can not be a cyclone at 
 the Equator. Thus far none have been observed between latitude 
 10° north and latitude 9° south. 
 
 But it is within tropical regions that the lower air becomes 
 most heated and contains most moisture ; hence, under favorable 
 circumstances, an important class of cyclones start in these regions. 
 Not only the starting, but the growth and movement of an exten- 
 sive cyclone depend chiefly on such a combination of circumstances 
 as may conspire to produce an abundant supply of ascending warm, 
 moist air on the front, and descending cold, dry air in the rear. 
 
 A cyclone may be started by the penetration of a cool current imder 
 one that is strongly heated. This causes the beginning of an uprush. 
 Cyclonic storms have been thus started in the neighborhood of Texas 
 and Florida by north winds sweeping under the warm, moist an- sus- 
 pended over the Gulf and the neighboring ocean. Many originate on 
 
 the Atlantic near the African coast, as well as near the Windward 
 Islands. 
 
 North of the Equator, these storms occur most frequently from Au 
 gust to October; south of it, from January to March. It is always dur- 
 ing the season of the gi-eatest heat, or at the limit of this season, that 
 cool polar currents encroach upon heated areas. 
 
 Progressive Motion of Cyclones. — In the northern 
 hemisphere, the wind blows toward the east on the southern side 
 of a cyclone (see Ji'gure, p. 71). Hence, according to Ferrel's Law, 
 the deflecting force toward the right causes a pressiu-e toward the 
 Equator. On the iiorthern side, the wind blows toward the west, 
 and the deflecting force causes a pressure toward the pole. Bi;t 
 this force is greater as we recede from the Equator; hence the 
 pressure toward the pole exceeds that toward the Equator, and a 
 cyclone when once started must move northward. South of the 
 tropical calms, it must also move westward in obedience to the 
 same forces that cause the trade-winds ; north of them, it must 
 move with the anti-trade winds. The c^'clones of the northern 
 hemisphere, therefore, have a progressive movement that is con- 
 tinually deflected toward the right. 
 
 By similar reasoning, it may be shown that cyclones in the 
 southern hemisphere must have a progressive movement with con- 
 tinual deflection toward the left. 
 
 The curve described by a cyclone in its path is very similar to that 
 called the parabola {see figure beloiv). In the Noi-th Atlantic Ocean, the 
 southern extremity of the parabolic track is usually near the Windward 
 Islands, or east of them. The northern branch passes over Newfound- 
 land, or south of this island. The most abrupt part of the cui-ve is be- 
 tween the meridians of 40° and 100^ in west longitude, most frequently 
 between those of 65° and 85°. 
 
 In this progressive motion, there is no actual transfer of the atmos- 
 phere from tropical to polar regions. The forces producing gyratory 
 motion being greater on the polar side, new bodies of air ai'e continu- 
 ally di'awn in. On the equatorial side, where these forces are less, the 
 various resistances that the cyclone has to encounter in its pathway 
 are more efi'ective, so 
 that the storm-center is 
 continually shifted into 
 new regions of atmos- 
 phere successively far- 
 ther away from the 
 Equator. 
 
 On the advancing 
 side of the cyclone, the 
 rainfall is heavier, the 
 temperature is higher, 
 and the change of baro- 
 metric pressure is more 
 abi'upt, than in the rear 
 portions of the storm- 
 area. As it approaches 
 a place within the trop- 
 ics, the atmosphere is of- 
 ten observed to become 
 hazy and sultry ; then 
 the barometer, which 
 may have been higher 
 than usual, begins to 
 
 fall ; a breeze springs up, and the sky in the direction of the com- 
 ing storm grows black with clouds which soon cover the heavens ; 
 wind and rain then exert their utmost fury. After the storm-center 
 has passed, the temperature falls very decidedly, and the wind and rain 
 gradually subside. 
 
 Duration and Rate of Progress. — The progress of a 
 cyclone within the tropics is slow, being often as little as ten miles 
 an hour. As the storm advances into cooler regions where the 
 
 Progressive Motion of Cyclones. 
 
IRREGULAR CYCLONES AXU TORNADOES. 
 
 75 
 
 snpj)ly of moist air is less, its rate of progress increases and the 
 area of disturbance widens. The central area of calm widens also, 
 and the gyratory motion becomes gradually less violent. 
 
 Some cyclones become dissipated by the down-rush of air at 
 the tropical zone of cahn.s, and therefore la-st but a day or two. 
 The more violent storms cross this zone and travel far into middle 
 latitudes, lasting a week or,more. They die out because the supply 
 of vapor in colder regions is insufficient, while the energy of the 
 cyclone is expended on a larger mass of air. The diameter of the 
 storm-center grows to 80 or 100 miles, and that of the entire 
 cyclone may finally exceed 1,000 miles. 
 
 Storm-Cards. — The general law of storms, as thus set forth, 
 enables us to know the direction from which cyclones may be ex- 
 pected. In northei-ii middle latitudes they come from the south- 
 west, almost with the antitrade winds. P'or any given place, 
 therefore, a storm-card may be constructed, in which the straight 
 arrow (A B, figure) marks the direction of progress, and the spiral 
 arrows show the course of the wind around the storm-center. In 
 the north temperate zone, the mariner, turning his back to the 
 direction from which the wind comes, knows that the place of 
 greatest danger is on his left in front, and hence steers to the 
 
 right to avoid it. In 
 the southern hemi- 
 sphere, he would steer 
 to the left. 
 
 Many of the West 
 Indian cyclones, after 
 crossing the tropical 
 zone of cahus, sweep on 
 over the Gulf Stream 
 and include the coast 
 of tlie United States in 
 the area covered. At 
 Savannah, the storm be- 
 gins with a wijid from 
 the east or northeast. It 
 then veers to the north, 
 and dies out while com- 
 ing from the west, the 
 path of the storm-cen- 
 ter being over the ocean. 
 On the next day, the same order of succession is observed at Washing- 
 ton, but with less violence, the central area having moved much farther 
 eastward. Not infrequently the cyclone crosses tlie Atlantic, and is felt 
 on the western shores of Europe. (On the hurricane season in the Wind- 
 ward Islands, see Ober's ''Camps in the Caribbees,'^ j). -162.) 
 
 If the storm reaches the Gulf of Mexico before crossing the belt of 
 calms, its center may traverse the Mississippi Valley and even surmount 
 the Appalachian Moimtains, expending its last energy upon the Atlantic. 
 
 Irregular Cyclones. — Cyclones of less violence and regu- 
 larity than those just described, are produced in temperate regions 
 wherever the equilibrium of the atmosphere can be disturbed by 
 heat. Such storms, imperfectly developed, occur in all parts of 
 the United States. They often join or partially oppose one an- 
 other, so that the oscillations of the barometer become irregular, 
 and the .shifting of the wind may at times seem unaccountable. 
 Probably most of the changes of the barometer are due to cyclone- 
 motion, however slight this may be. 
 
 In smnnier. the great plains of Kansas and Nebraska become warmer 
 than either the wooded valley of the Mississippi or the Rocky Mountains 
 on the west. Large areas of elongated or irregular shape are covered 
 with rarefied air, and toward such "barometric troughs" wind blows 
 from all sides. In accordance with Ferrel's Law, the motion soon be- 
 
 Storm-Card kor Northern Middle Latitcdes. 
 
 comes cyclonic, and the storm i)asses eastward to the Middle and North- 
 ern States. 
 
 Tlie laud <jn the Pacific slopes becomes lieatcid, and moist air fi-om 
 the ocean is brouglit abundantly by the anti-trade winds to supply the 
 areas of low bai-ometer thus started. Cyclones are hence developed, 
 many of which pass over the Rocky Mountains and traverse the entire 
 continent. (For further information on this subject, consult Professor 
 Ferret on " The Motions of Fluids and Solids on tite Earth''s Surface;" 
 and Uptoti's ''Investigation of Cyclonic Plienotnenu," in tlie "Ameri- 
 can Meteorological Journal," vol. Hi., pp. 250, 316, 367.) 
 
 Tornadoes may be defined as local cyclones of exceeding 
 violence, in which the area covered is too small for the gyratory 
 motion to be always determined by deflection due to the earth's 
 rotation. 
 
 A tornado occurs only when the earth's surface is greatly heated 
 and the air is calm and sultry. The upper layer of atmosphere 
 rests in a state of unstable equilibrium over the rarefied layer next 
 the ground. If from any slight cause whatever this equilibrium 
 be disturbed, the upper layer is penetrated by an ascending cur- 
 rent, which is followed by currents of various degrees of strength 
 that meet below from all sides. Since these seldom balance one 
 another exactly, gyratory motion in either direction is at once 
 established. 
 
 To illustrate this, remove the plug very gently from the bottom of a 
 basin full of still water. The water flows out qiuetly ; but, if the least 
 motion is imparted in any direction next to the opening, gyratoi'y motion 
 in the same direction is deternuned and rajjidly increases in violence. 
 The surface of the water becomes fimnel-shaped, and air is sucked down 
 with ihe outflow. 
 
 Comi>arison of Cyclones with Tornadoes. — The con- 
 ditions that occasion a tornado may also give rise to a cyclone, if 
 they prevail over an area of great extent. In this event, the influ- 
 ence of the earth's rotation in determining the direction of gyration 
 exceeds all others, and being constant it tends to lengthen the life 
 of the cyclone. A tornado quickly becomes extinct, seldom lasting 
 more than a few hours, because of the resistance it encounters from 
 the surrounding air and the earth. It may occur, moreover, within 
 the equatorial zone of calms where cyclones are impossible. 
 
 At a distance from the Equator, the gyratory motion of torna- 
 does is usually like that of cyclones in the same hemisphere. Thus 
 in the United States, it is opposite to the motion of the hands of a 
 watch, and the direction of progress is generally northeastward. 
 Tornadoes generally occur on summer afternoons, though occa- 
 sionally during spring or .autumn, and more frequently over arid 
 plateaus than wooded low plains. The Western States are oftener 
 visited by them than other sections of the Union. {Consult Lieu- 
 tenant Fhiley's ^'■Characteristics of Tornadoes," and Ferret's 
 " Recent Ad ra7ices in Meteorology^'' 1886 , iniblished hy the United 
 States Signal Seri-ice.) 
 
 The path of a tornado is sometimes only a few rods in width. The 
 centrifugal force developed in gyration so close to the axis is enormous, 
 and the diminution of atmospheric pressure at the center is such as to 
 create almost a vacuum. Hence, when a tornado passes over a building, 
 the sudden expansion of the air within the structure bursts it into frag- 
 ments. The whirling mass of air around the axis moves solid masses 
 many tons in weight, and scatters lighter objects like chaff on either 
 side of its track. 
 
 On the 1-lth of April, 1886, a tornado passed over a part of Minne- 
 sota, destrojdng about a himch-ed lives, and property valued at nearly 
 half a million of dollars. Houses were wrecked, freight-cars lifted from 
 the tracks, and in st>me places iron rails were wrenched from the cross- 
 ties. Fragments of debris were hurled into the air, and carried more 
 than twenty nules before falling. (Consult '^Scientific Americaji" for 
 Man 1, 1886; and Professor Shaler's " Aspects of the Earth," p. SJ^O.) 
 
ATMOSPHERIC VAPOR, ITS SOURCE AND PROPERTIES. 
 
 The approach of a tornado is heralded by dark clouds which 
 meet from opposite sides of the sky. Gyratory motion is estab- 
 lished, and warm air is drawn up into the vortex from below. 
 All ascending, t-ndsting column of dust and condensing vapors 
 spreads out spirally as it joins the cloud above, and causes this to 
 assume the form of a dai'k, whirling funnel, with its smallest part 
 below. As the motion increases in violence, the stem of the fun- 
 nel descends, until it sweeps the ground, destroying whatever it 
 touches. 
 
 The column has a progressive motion, that vai-ies from fifteen 
 to sixty miles an hour, often rising and descending at intervals. 
 The rushing of the conflicting currents, frequently accompanied 
 with flashes of Lightning, produces a loud, roaring sound. After 
 the work of progressive devastation has been continued a few min- 
 utes, or at most a few hours, the mass of cloud overhead breaks 
 into torrents of rain and hail, and the tornado is soon extinct. 
 
 Water-Spouts and 
 Sand-Pillars. — When a 
 tornado occurs at sea, the 
 funnel - sliaped cloud de- 
 scending to the surface of 
 the water draws tliis tip 
 into the column of whirl- 
 
 mg, rar 
 
 efied 
 
 into spray. 
 
 air. 
 and 
 
 breaks it 
 thus con- 
 
 nects the cloud with 
 surging waves below. 
 
 the 
 Ee- 
 volving columns of water 
 and air thus created are 
 called " Water-spouts." 
 
 Similarly, when a tor- 
 nado sweeps over a desert 
 of sand, cloitds of dust are 
 lifted up in the vortex. 
 Such "Sand -Pillars" are 
 greatly dreaded by travel- 
 ers on the Sahara and Ara- 
 bian Deserts. 
 
 Q,uestions. — State the cause of 
 the incessant motion which 
 takes place in the atmos- 
 phere. Whatarewind-zones? 
 Calm-belts ? Can their lim- 
 its be defined ? Account 
 
 for irregularities in wind-zones. What are trade-winds ? Anti-trades ? 
 Why are these winds so called, and in what directions do they blow ? 
 Name the regions in which the winds are constant, periodic, or variable, 
 stating the cause in each instance. Describe the polar winds and their 
 effects. Explain land and sea breezes. What are monsoons, and how do 
 they affect prevalent winds ? Mention the most noted hot and cold winds, 
 and state where each prevails. 
 
 Define a storm. Explain the cause of storms. Account for the spiral motion 
 of cyclones. Describe the curve along which a cyclonic storm moves ; the 
 width and length of its path; its rate of progress and duration; the ac- 
 companying wind-pressure. In what direction do cyclones sweep over 
 the United States, and why ? What are storm-cards ? Illustrate the pro- 
 duction of a tornado. State the difference between a tornado and a 
 cyclone. Describe the destructive effects of a tornado. What is a water- 
 spout ? 
 
 Why does a west wind bring fine weather to the Middle Atlantic States, 
 while east and south winds are accompanied with storms ? Where are 
 easterly winds chiefly prevalent, and at what seasons ? Of what value are 
 winds in the economy of Nature ? 
 
 Water-Spout in the Strait of Malacca. 
 (From a sketcli made in 1872.) 
 
 THE MOISTURE OF TEE ATMOSPHERE. 
 
 Vapor. — The gases composing the atmosphere have been al- 
 ready mentioned. Their relative proportion remains very nearly 
 constant, except in the case of watery vapor. Next to nitrogen 
 and oxygen, this is the most abundant ingredient. In its relation 
 to chmate, it is the most imjjortant of all. 
 
 Source and Properties. — All the moisture in the air 
 comes from the sea, either directly or indirectly. Vapor is con- 
 tinually rising from the surface of every exposed body of water. 
 It is only three-fifths as heavy as air, and is therefore easily swept 
 up by atmospheric currents and widely diffused. 
 
 What is poi^ularly called vapor cousists of small particles of 
 licpiid due to the condensation of an invisible gas. When vaj^or 
 rises from sea- water, the salt is left below in solution. The saltness 
 
 of sea-air is due to finely di- 
 vided spray which is caught 
 from the waves and wafted 
 high up by the wind. 
 
 Saturation and 
 DrjTiess.-— A cubic foot 
 of air at 30° Fahr. can hold 
 only two grains of invisible 
 vapor; but, if the temper- 
 ature be raised to 100° F., 
 the same volume will con- 
 tain nearly twenty grains. 
 When thus holding all that 
 it can carry of perfect va- 
 por, the atmosphere is said 
 to be saturated. If a body 
 of saturated air at 100° F. 
 be cooled to. 30° F., then 
 nine- tenths of its vapor will 
 be condensed into a visible 
 cloud of minute drops of 
 water. Air which contains 
 but a small proportion of 
 the vapor that it can hold 
 at a given temperature is 
 said to be to that extent 
 dry. Thus, if saturated 
 air at 3t)° F. be warmed up 
 to 100° F., it becomes nearly dry, since it now carries only one- 
 tenth of what it has the capacity of holding in the gaseous state at 
 this temperature. 
 
 Dew-Point. — By many careful experiments the amount of 
 vapor that a cubic foot of perfectly dry air can contain before be- 
 coming saturated has been ascertained for various temperatures. 
 Thus, at sea-level, it is 6.15 grains for 62° F., whicli is estimated to 
 be the mean surface temperature of the globe. If a body of un- 
 saturated air at 10: >° has to be cooled down to 62° before any of its 
 vapor begins to condense, this temperature, at which saturation is 
 reached, is called its dew-point. The drier the air, the lower its 
 dew-point. 
 
 Absolute and Relative Humidity. — The quantity of 
 vapor that a given volume of air actually contains at a certain tem- 
 perature, is a measure of its absolute humidity. The ratio of this 
 
EVAPORATION AND PRK(; I P I T ATI ON OF VAPOR. 
 
 I i 
 
 (piaiititj' to that which woukl saturate it at the same temiierature, 
 is its rdailrc huiaidity. 
 
 Thus, if a cubic foot of air at inO° has to he cooled to 62" to become 
 saturated, then (!. 15 grains represent i(s absohite hunndity. But at 100° 
 it woukl require 19.8 grains for complete saturation. Hence its relative 
 humidity is ^v'.l- or about 31 per cent. The lower the percen*age of rela- 
 tive humidity, the greater is the fall of temperature required to produce 
 saturation or reach the dew-point. 
 
 Rate of Evaporation.— The lower its relative humidity 
 also, tlie i,'reater is the air's jjower of taking up va[)or from water 
 with which it is in contact. The process of evaporation hence 
 goes on more rapidly in sunshine than in shade, on a warm day 
 than on a cold one, witli clear than with overcast skies. 
 
 Assume a surface of water to be covered with still air; as soon as 
 this becomes saturated, evaporati(.>n ceases. But, if swept by wind, the 
 relative huniidity of that which hi iefly touches it in passing can never 
 be much raised, especially if the air be warm. Evaporation is hence 
 more rapid in equatorial than m temperate regions, and most of all in 
 the warm belts constantly swept by the trade-winds. 
 
 Evaporation also varies with the pressure of the atmosphere. If the 
 air be dense, there is little room left for additional vapor of water. But, 
 in proportion as it becomes more i-arefled, evaporation is more rapid. 
 If a liquid be exposed to a vacuum, the space over it becomes in- 
 stantly saturated with va- 
 por. Hence, when the ba- 
 rometer falls, evaporation 
 becomes corre.spondingly 
 more rapid. 
 
 Vapor - Tension. 
 
 — The vapor that satu- 
 I'ates a space otherwise 
 empty exerts a definite 
 pressure, the measure of 
 which is called the va- 
 por-tension. Thus, if the 
 pressure of the dry at- 
 mosphere at (>2° F. he 
 thirty incites, as meas- 
 ured on the barometer, 
 that of water-vapor un- 
 mixed with air at the same temperature is a little more than half 
 an inch, or ahout one-sixtieth as much. If mixed witli air and not 
 at the point of saturation, the vapor exerts less pressure. Vapor- 
 tension is increased by heating and diminished by cooling. Its 
 
 amoimt at any place is pro- 
 g g portional to the absolute 
 
 i g I huniidity of the air. 
 
 In the diagram above, where 
 the names of the months are in- 
 dicated by their initial letters at 
 the top, it will be seen that the 
 temperature-curve for the year 
 (T) is low in January, high in 
 .July, and low in December. 
 The vapor-tension, or vapor- 
 pressure (V P), also rises in 
 summer and falls in winter, 
 though not in the same ratio. 
 It is an index of the absolute 
 humidity. The relative humid- 
 ity (R H) is lowest in sum- 
 mer, though the increased heat 
 during this season causes the 
 absolute amount of vapor car- 
 
 
 F 
 
 M 
 
 A 
 
 M 
 
 J 
 
 J 
 
 A 
 
 S 
 
 
 
 N 
 
 D J 
 
 RH 
 
 1 
 
 \ 
 
 
 1 
 
 1 
 
 / 
 
 1 
 
 1 
 
 1 
 
 
 / 
 
 1 
 
 VP. 
 
 
 / 
 
 / 
 
 Z^-- 
 
 
 
 
 
 N 
 
 \ 
 
 — - 
 
 T 
 
 
 / 
 
 
 
 
 
 
 
 
 \ 
 
 V 
 
 V.P. 
 
 Annual Changes of Temperature (T.), 
 varor-pressure (v. p.), and 
 Relative Humidity (R. n.). 
 
 10 13 
 
 10 13 
 
 Change of Relative Humiditt during a 
 Single Day. 
 
 ried in the air to be far in excess of that in winter, often four or five times 
 as much. 
 
 In like manner, during a single day, the relative humidity varies, being 
 lowest during the warmest part, of the day and highest just after dawn. The 
 daily variation in summer, from 50 to 80 per cent., is also seen to be much 
 greater than that in winter, from 80 to 80 \Kr cent., on the days for which 
 these curves were constructed. 
 
 Measurement of Evaporation.— By exposing a known 
 area of water-surface and recording the daily decrease of depth, it 
 is possible to estimate the total loss by evaporation during the year. 
 Thus, at a reservoir in India, during the dry season of two hundred 
 and forty days, the daily decrease of depth was over one-fifth of 
 an inch, or in all more than four feet. For the whole year, it was 
 about six feet. 
 
 The amount of rainfall may also be measured by catching the 
 falling water in an appropriate instrument called a rain-gauge. By 
 comparison of results, it has been found that for any single coun- 
 try the amount of water lost by evaporation is about equal to that 
 gained by rainfall. There is hence no great amount of water 
 transferred through the air from the toi-iid to the temperate zone 
 by the upper trade-winds. {Consult Hauyhton^s ''Six Lectures on 
 Physicai Geography" j^- 165.) 
 
 Distribution of Vapor according to Elevation. — 
 
 Although vapor is lighter than air and hence tends to lise, it ex- 
 pands at a faster rate in ascending, so that the cpiantity actually 
 held by the air rapidly diminishes with increase of height. It is 
 estimated that fully half of all the vapor is within 6,500 feet of sea- 
 level, and that not one-tenth of it remains after an elevation of four 
 miles is reached. Hence the climate of lofty plateaus is usually 
 very dry. Vapor, moreover, is a powerful absorber of terrestrial 
 radiation ; its partial absence contributes largely to the extremes 
 of heat and cold that are felt at such heights. 
 
 Pi*ecipitation. — When the temperature of the air is reduced 
 to the dew-point, the vapor it contains is precipitated, and the 
 result may be dew, frost, fog, cloud, rain, snow, sleet, or hail, 
 according to circumstances. 
 
 Dew and Fl'ost. — When at night the earth radiates the heat 
 which it has received during the day, the surface becomes colder 
 than the ground beneath or the air above. Vapor rises from the 
 moist soil below, to be condensed at the cooler surface. The ad- 
 jacent layer of air above is also cooled to its point of saturation, 
 and its vajjor is deposited. This condensed moisture at the surface, 
 whether from the soil or the air, is Dew. When the weather is 
 cold, so that but little vapor can be carried in the air, the dew-point 
 may be below 32° Fahr. In this event what is deposited is solid 
 Frost. 
 
 The difference of temperature between points four inches and 
 four feet above the ground may he as great as 12° or 15°, so that frost 
 may be deposited when the temperature of the vast body of over- 
 lying air is above 40°. The freezing often takes place before 
 the depdSi, and thus the ground may be spangled with minute ice- 
 crystals. Dew does not fall, but is condensed on the best radiators, 
 such as grass and trees. {See Wells 's "Essay on Dew.") 
 
 In the deu.se forests of South America, Humboldt found that during 
 the night there was apparently a shower of rahi, while the sky overhead 
 was cloudless. In the warm tropical atmosphere, radiation occurred 
 chiefly from the trees, whose foliage was so dense as to screen the 
 ground. The precipitation was sufficiently rapid to produce a gentle 
 shower from the leaves. The same is observable to a less extent in the 
 woods of Florida and other states bordering the Gulf of Mexico. 
 
7S 
 
 ORIGIN OF CLOUDS. — CLOUD-FORMS. 
 
 Dew and frost are much less abundant when the sky is cloud- 
 ed, or on a windy night. The clouds reflect the heat which would 
 otherwise be radiated into space, and wind prevents the air from 
 remaining long enough in contact with a single radiating surface 
 to permit of any noticeable lowering of temperature. 
 
 It is estimated that the average annual deposit of dew on the earth's 
 surface does not exceed 1.5 inches. This is greatly exceeded iu the 
 tropics, especially near large bodies of water that give abundant moist- 
 ure to the air. In the rainless re- 
 gions of Peru, dew is an important 
 agent in sustaining vegetation. In 
 Palestine, and on the plains of 
 southern Texas, the deposit is phe- 
 nomenally heavy ; while in the 
 Arctic regions there is little or no 
 dew. 
 
 Sheet-Ice. — If the ground 
 becomes very cold and is then 
 swept by an atmospheric wave 
 of warm and moist air, the de- 
 position of ice may become such 
 that all exposed objects are cov- 
 ered with a slippery sheet which 
 grows in thickness imtil the 
 ground is warmed above the 
 freezing-point. This result is 
 greatly intensified if a gentle 
 rain falls at the same time. 
 The limbs of trees become in- 
 cased so thickly as to break un- 
 der the load. A twig four inch- 
 es long and weighing less than 
 eight grains has been known to 
 be covered with ice weighing 
 over 920 grains. " Ice-storms " 
 of this kind cause great de- 
 struction of property at times, 
 and have interfered seriously 
 with telegraphic communica- 
 tion. {See Pike's artiole on Ice- 
 Storms, '■^American Meteorolog- 
 ical Journal,''^ vol. Hi., p. 33.) 
 
 Fog and Clouds. — If a body of moist air becomes cooled 
 below its dew-point, by radiation or otherwise, its vapor is pre- 
 cipitated in minute droplets that float on account of their diminutive 
 size. If this occm- over the surface of the ground or of water, 
 the result is called Fog ; if at an elevation, it is termed Cloud. If 
 the dew-point be low enough, as it is at great elevations, the cloud 
 may be composed entirely of minute crystals of ice. 
 
 The formation of fog is much facilitated by the presence of dust or 
 smoke iu the air. Each floating particle serves as a nucleus around 
 which the vapor condenses. A large manufacturing town is hence more 
 liable to be visited with fog than the open counti-y. Fog ii^^equently 
 present in London when the atmosphere twenty miles distant is com- 
 paratively clear. 
 
 Since the temperature of a large mass of water is imparted to the air 
 resting upon it, fogs are specially abundant in the neighborhood of New- 
 foundland where the Gulf Stream meets the cold Arctic current. In 
 like manner an iceberg, after floating southward within the limits of the 
 same mass of warm water, is attended with fog, which increases the 
 danger of navigation in its neighborhood. 
 
 " Dry fog " is a name improperly apphed to the haziness of the air 
 due to suspended particles of dust or smoke. It is often produced by 
 
 Varieties of Cloitd-Forms. 
 
 forest-fires in America. Rain falling through it may become slightly 
 discolored. For nearly two months, in 1783, the whole of Europe was 
 covered with an extraordinary dry fog. 
 
 Formation of Clouds. — Moist air, in ascending, becomes 
 cooled by expansion. Its vapor, at first invisible, is condensed 
 into visible clouds. The height at which condensation begins 
 varies with the dew-point at the surface. In tropical regions, 
 where the lower strata of air are warm, clouds seldom float nearer 
 
 than a mile and a half above 
 the ground, but often at heights 
 exceeding four or live miles. 
 In polar regions, on the con- 
 trary, the conditions are neai-ly 
 always such as to permit their 
 formation at or near the surface. 
 According to circumstances, a 
 cloud may be dissipated by the 
 sun's heat above while receiving 
 accessions from moist air below, 
 or its lower part may be dissi- 
 pated by descent mto warmer 
 and drier air while accessions 
 are received from above. 
 
 Classification of 
 Clouds. — Several modes of 
 classifying clouds have been 
 proposed, but that most gener- 
 ally in use at present is the old- 
 est, and was adopted about the 
 beginning of the present century 
 by Luke Howard. He divides 
 them into thi-ee primary types, 
 from which other types are de- 
 rived by combination, viz., Cir- 
 rus Clouds, Stratus Clouds, and 
 Cumulus Clouds. 
 
 Cirrus Clouds (from a 
 Latin word, moaning tuft of 
 hair) appear at the loftiest 
 heights as long, feathery streaks 
 of delicate white spray (see up- 
 per left-hand corner of the engraving). From a balloon four miles 
 high they have been seen still far beyond in the blue sky, where the 
 temperature was necessarily much below the freezing-point of water. 
 Cirrus clouds are composed of minute crystals of snow, grouped 
 together in filaments that are stretched out by currents of air. 
 They are supposed to indicate changeable weather ; often to herald 
 approaching wind and rain in summer, frost or snow in winter. 
 
 Stratus Clouds (see lower right-hand corner of plate) are 
 arranged in hoi-izontal layers or strata, particularly on the smnmer 
 horizon at night and in the early morning, when the ground and 
 lower atmosphere have become cool by radiation. They are due 
 to the gradual falling of clouds that have been floating at greater 
 heights, and sometimes settle in the valleys as fog to be dispersed 
 by the morning sun. In winter they often cover the sky for days 
 with a dull-gray mantle of no great thickness ; but in summer they 
 are the night-clouds, which disappear after sunrise. 
 
 Cumulus Clouds (literally, heaps) are those most frequently 
 seen during the day in summer, forming white masses like balls of 
 
VARIETIES OF C LOU DS.— R A I N. 
 
 79 
 
 cotton, which rest on a thicker base that is sometimes almost liori- 
 zoutal (No. 4, in the circle). The half-globular masses are the de- 
 scending bodies of condensed vapor, which thicken as they approach 
 the lower limit, where they are dissolved by the warmer air below. 
 They may be entirely dispelled by the sun, or condensed still 
 further into rain by cool winds. 
 
 When cuTus clouds have gathered sufficiently, they may settle into 
 layers, like stratus clouds, hig-h up m the air. These are called cm-o- 
 strafus (No. 3, in the circle), and often form a network covering the 
 whole sky. As they sink still lower, they become dark by increased 
 condensation, and constitute an almost unfailing sign of rain or snow. 
 
 Cirrus clouds in descending sometimes break into patches like those 
 of the cuunilus cloud, but still at great height. Such clouds are called 
 cirro-cumulus (upper right-hand corner of plate), and the sky studded 
 with tliem is popularly termed a " mackerel sky." 
 
 Cumulus clouds increase in height as the day advances, and often be- 
 come much denser and darker beneath. With tliis darkening, the ui)per 
 mas>e-i may tlatfen out, producing a form approximating the stratus. 
 They are then called cnmido-stratus (No. 5, bottom of circle). 
 
 Kaiii-Cloiids. — Any of these forms of cloud may increase in 
 density to such an extent that the minute floating drops unite to 
 form full drops that fall. The dark rain-cloud which thus results 
 is called Nimbus (lower left-hand corner of plate), and often begins 
 to form perceptibly at the base of the cumulo-stratus clouds. 
 
 The size of the rain-drops depends upon the height and thickness of 
 the rain-cloud, and the difference of temperature between the bodies of 
 air whose mixtui-e has caused precipitation. Each drop in falling meets 
 with multitudes of miimte droplets which compose the cloud, and are 
 added to the descending nucleus of water. The growth which tlie drop 
 attains is far greater in summer than in winter, not only because summer 
 clouds are higher, but also because the absolute humidity of the rLsing 
 warm currents is so much increased by the surface-heat radiated from 
 the ground. This in turn causes the currents to ascend faster, and pre- 
 cipitation is thus more rapid. In the central area of a cyclone, where 
 the dense cloud may be several miles in thickness, the big di-ops fol- 
 low so closely that the rain seems to fall in unbroken sheets. Winter 
 rains, on the contrary, are often little else than falling mist, particularly 
 in high latitudes, where clouds are suspended but a few hundred feet 
 above the ground. 
 
 Clouds as Protectors. — Clouds not only serve as the 
 gatherers and distributors of rain over the greater part of the earth, 
 as moderators by night of rapid evaporation from the soil warmed 
 during the day by solar heat — but they also play an important part 
 in torrid regions, as absorbers of the scorching rays of the sun, and 
 thus afford protection to animal and vegetable life. As cloudless 
 regions are always rainless regions, a desert is partly a cause and 
 })artly an effect of the absence of clouds. 
 
 Motion of Clouds. — At small elevations, clouds are wafted 
 in the direction of the surface-wind, but at a much faster rate, be- 
 cause they move with air that is not retarded by friction against 
 solid bodies. At great elevations, their direction is usually different 
 from that of the lower clouds. Cirrus clouds thus serve to indicate 
 the direction of upper currents that could not otherwise be traced. 
 
 Cloud-Tints. — The colors so often seen on clouds are due 
 sometimes to reflection, sometimes to absorption of light. The 
 tine particles of vapor, while absorbing all wave-lengths to some 
 extent, transmit the long waves more easily than the short ones, 
 and reflect the short ones in larger proportion. The light reflected 
 from the front of a dense cloud is bluish. If the sun be directly 
 behind it, the light transmitted through its edges is reddish or 
 golden. {(Consult Professor Hood^s ^'^ Modern Chromatics^'' pp. 
 55, 56.) 
 
 R A I M. 
 
 Tlie ( 'liicf Cause of Raiu has been already indicated — 
 the cooling of a current of damp air. In rising, such a current 
 expands, and therefore becomes cooled until the dew-point is 
 passed. We have seen that perfectly dry air would be cooled by 
 expansion, 1° Fahr. for about 182 feet of ascent. If we assume 
 the surface-temperature to be that of an oppressive summer day, 
 100° F., such air would be cooled to 40° below zero by rising five 
 miles. But the air is never perfectly dry ; hence precipitation 
 must occur. This in turn implies the production of heat, so that 
 the rate of cooling is variable, and not so rapid as it would be for 
 dry air. Descending currents do not produce rain. 
 
 Other causes of rain are the cooling of damp air by pa.ssage 
 over the land from the warm sea, and to a small extent the mixture 
 of ciu'rents of air differing in temperature. 
 
 Warming Effect of Rain. — When the condensation of 
 vapor into rain is copious, the heat evolved rapidly changes the 
 tem[)erature of the air. We have seen that this is a very imjwr- 
 tant element in prolonging the life of a cyclone. A gallon of 
 water weighs ten pounds, and if spread out so as to form a layer an 
 inch thick it would cover aliout two square feet of space. To 
 cover a square tnile an inch in depth, 00,000 tons of rain are re- 
 quired, or twelve millions of gallons. In the condensation of the 
 vajjor needed to produce a single gallon, heat enough is given out 
 to melt seventy Ave pounds of ice, or to make forty-five pounds of 
 cast-iron white-hot. An inch of rainfall on each square mile hence 
 implies the evolution of heat sufficient to melt a layer of ice spread 
 over the ground eight inches thick, or to liquefy a globe of iron 
 130 feet in diameter, or a rod of it a foot in thickness and 260 
 miles in length. 
 
 Dr. Haughton estimates the heat given to the west coast of Ireland 
 by rainfall to be equivalent to half of that derived from the sun. At 
 certain stations in India the annual rainfall is four times as great as that 
 on the west of Ireland. (Consult HaugJiton's " Six Lectures on Physi- 
 cal Geography,'" p. 126.) 
 
 Effect of Rain on Climate.— The climate can never be 
 cold where the number of rainy days during the year is large. At 
 Valencia, in the southwest of Ireland, rain falls usually on 235 days 
 of the year, or about two days out of e\-ery three ; and to the heat 
 thus brought through the air from the Gulf Stream is chiefly due 
 the rich verdure of the Emerald Isle. The entire western coast of 
 Europe takes its equaljle climate thuS largely from the ocean. 
 Even when rain does not fall, the atmosphere, laden with vapor and 
 clouds, checks radiation and keeps the surface warm. 
 
 Effect of Wind on Rainfall. — If the wind blows from 
 cool to warm regions, however saturated the air may be at first, its 
 relative humidity decreases with rise of temperature, and no clouds 
 can be formed. Rainfall is thus impossible. The trade-wind re- 
 gions on the ocean are hence almost rainless during a large part of 
 the year, though the absolute humidity of the air is high. 
 
 If the wind blows from warm to cool regions, however dry the 
 air may be at first, its relative humidity increases with fall of tem- 
 perature, and clouds are fonned. Rainfall thus becomes possible. 
 The anti-trade-\\-ind regions on the ocean are frequently visited 
 with rain. 
 
 The annual amount of rainfall at any place is hence largely deter- 
 mined by the du-ectiou of the prevailing winds. This is equally true ofi 
 rainfall during particular seasons, and of mdividual rain-storms, i As 
 
ILLUSTRATIONS OF EXCESSIVE AND DEFICIENT RAINFALL. 
 
 Mean Annual Rainfall for the DiFFERf;NT Counthies of the Globe. By Professor Loomis, of Yale College. 
 
 ft is sufficient to darken the sky and raise the temperature 
 ly within a few hours. 
 
 [■ Land-Masses on Rainfall.— Since heat is more 
 ed and absorbed by land than by water, winter rains 
 regions are often due largely to southwest winds blow- 
 warm ocean to the cool land. This causes the " rainy 
 e Pacific coast of the United States. But through- 
 le year, and especially in siimmer, the land becomes 
 Lg the day, and vapor-laden winds on reaching it are 
 upward and condensed into rain. This effect is in- 
 : land be mountainous. The wind forces its way up 
 ■sides and its vapor is rapidly condensed. Mountain- 
 is the most important of all natural condensers. Any 
 IS over them is deprived of moisture and blows as a 
 
 f Vegetation on Rainfall. — Forests protect the 
 the direct rays*of the sun, and prevent the rapid evap- 
 ;h moisture as the soil contains. The temperature of 
 ist is hence much lower, during the hours of sunshine, 
 lir over a desert. A body of saturated air, if wafted 
 is apt to yield rain ; but over a desert its relative hu- 
 Duce depressed, and the clouds change into invisible 
 'roivii's '■'•Effects of Forests on Humidity of Climate!''') 
 
 ons of Excessive Rainfall. — In India, during the sum- 
 ;oon blows strongly and steadily, sweeping over the Bay 
 ■thward up the valleys of the Ganges and Brahmaputra 
 e surface, the average temperature exceeds 80° F. About 
 th of the coast, the Khasia Hills rise abruptly from the 
 in elevation of 4,125 feet stands the village of Cherrapoon- 
 in two sides by precipices 2,000 feet in depth, which close in 
 en southward to the plain. The warm and saturated wind 
 I to ascend nearly a mile above sea-level before surmount- 
 It is thus cooled below its dew-point, so that the greatest 
 3 at the level of Cherrapoonjee. Above this height the 
 to contain much vapor. 
 
 The average annual rainfall at the village, as determined by the rec- 
 ords of twenty years, is about 493 inches; and during special years it has 
 exceeded 600 inches, the largest amount on record. If prevented from 
 flowmg- away or evaporating, it would cover every inch of the plateau 
 on which Cherrapoonjee stands to the depth of fifty feet. Of this vast 
 amount of rain, 95 per cent, falls during the six months from April to 
 September inclusive. In July alone, the rainfall is over 133 inches, 
 which is at the rate of 4.3 inches each day, or as much in ten days as 
 falls during the whole year at New York. Thirty inches have been 
 known to fall in a single day. The January rainfall is less than an 
 inch, the wind being then from the northwest. The annual rainfall 
 thirty miles beyond Cherrapoonjee is only 100 inches, the air having 
 become comparatively depleted by ascending beyond the limit at which 
 the dew-point is reached. 
 
 The densely wooded plain of the Amazon, sloping gently toward the 
 Atlantic under the burning sun of the torrid zone, is characterized by a 
 heavy rainfall. The humid trade-winds, sweeping westward over a 
 radiating continent, already moist with luxuriant vegetation, are de- 
 pleted by a continuous precipitation which supports the magnificent 
 river system of South America. 
 
 In the region of anti-trade winds on the western coast of America, 
 the breeze blows from sea to land, and is quickly forced up the slopes of 
 the gi'eat momitain-ranges that in places border on the water. At sta- 
 tions in Alaska, the State of Washington, and ChiLp, the annual rainfall 
 varies from 100 to 125 inches, or nearly three times that at New York. 
 
 In the United States on the Atlantic side, the greatest annual rain- 
 fall is along the Gulf coast (about sixty inches) ; at Cape Hatteras, where 
 the warm Gulf Stream and cool Arctic currents first meet (seventy-eight 
 inches) ; and on mountain elevations like Mount Washington (seven- 
 ty-seven inches). (Consult Schott^s ^'Tables of Ram and Snoiv Pre- 
 cipitation in the United States,'''' second edition, Smithsonian Institu- 
 tion.) 
 
 Illustrations of Deficient Rainfall. — The most extensive rain- 
 less tract in the world is that which includes the deserts of Sahara, 
 Arabia, and Persia. Much of this is situated within the belt of dry 
 noi'theast trade-winds, and consists of lofty plateaus bounded by mount- 
 ain-ranges. Such moist winds as may at times blow from the ocean are 
 depleted on the shoreward side of the mountains, and, on surmounting 
 them, are reduced far below the dew-point. Even on the Mediterranean 
 side, part of which is not fringed with mountains, clouds from the sea are 
 
LAWS OF RAINFALL. — RAIN-ZOXES. 
 
 81 
 
 vaporized on reaching' the desert. Beneath a elondless sky, absorption 
 and radiation continually alternate, so that days of burning heat are fol- 
 lowed by nights sufficiently cold to congeal the moisture in the air, 
 which appears at dawn as frost on the gi-ound.- 
 
 The highlauds of Turkestan and ]^I()ngolia are similarly Ixnnuled by 
 lofty I'auges which prevent the free access of surface-winds from sur- 
 louiuling countries. Together they include the great Desert of Gobi, 
 which is separated from the Pereian Desert by the ranges that culminate 
 in the Karakorum Mountains. On the southern slopes of these, there are 
 copious shovrers due to ocean-breezes that have swept over the Indian 
 plain. But for this interruption, a continuous desert would extend from 
 the eastern limit of Mongolia to the .\tlantic, over 100° of longitude. 
 
 West of the Andes is a desert strip extending over the Peruvian and 
 part of the Chilean coast. The prevailing winds are from the east, and 
 hence are depleted by the lofty mountain-range. Evaporation from the 
 neighboring ocean supplies the air with moisture enough to furnish 
 abundant nightly dews, so that, though the region is rainless, most of it 
 is not sterile. South of the Calms of Capricorn, the anti-trade winds, 
 after producing very heavy rainfall on a continuation of the same coast, 
 are depleted in ^lassing over the mountains, and as the result of this most 
 of Patagonia is an uninhabitable desert. 
 
 The character of the trade-wind is strikingly illustrated by compar- 
 ing the rainfall at Pernambuco, Brazil, with that of Ascension, a small 
 mountainous island in the Atlantic, midway between Africa and South 
 Amei'ica. The latitude of each is about 8° south. At the former the 
 annual rainfall is 100 inches; at the latter, but little over three inches. 
 At each the absolute humidity is high. The air ascends on reaching the 
 Brazilian coast, but at Ascen.siou there is no cause sufficient to produce 
 upward motion. The island is, therefore, almost perpetually i)arched. 
 (On mean annual rainfall in different parts of the globe, consult Loom- 
 is's article in "American Journal of Science," vol. xxc, January, 
 1883.) 
 
 General Laws of Rainfall. — Rainfall is so much deter- 
 mined by local couditious that uo statement of general laws cau be 
 made without admitting many exceptional cases. The follo\ving 
 laws may be accepted as ronghly approximate : 
 
 I. In tonid regions the rains are more violent, and the total 
 rainfall is greater, than in high latitudes. 
 
 This is abundantly shown by referring to the rainfall of the East 
 and West Indies and comparing it with that of Arctic America and Asia. 
 The mean annual rainfall at the E(i[uator is estimated to be about one 
 hundred inches; at latitude 40°, about forty inches; and within the 
 Arctic Circle, less than ten inches. 
 
 II. Rainfall is generally most abundant on the coast, and be- 
 comes deticient in the interior of a continent. 
 
 An examination of the rain-map will make this law clear. It is true 
 in regard both to the violence of rainfall and the annual numbe*" of 
 rainy days. 
 
 III. The mmil)er of 2-ainy days and the general cloudiness in- 
 crease with increase of latitude. 
 
 The average ratio of cloudy and rainy days to clear days within the 
 tropics is about one to three, in Great Britain about one to one, and in 
 the Arctic regions three or four to one. 
 
 Rain-Zones. — Aside from the local influences that produce 
 rain on land, the earth's suriace lias been divided into ceiiain belts, 
 each of which has its own peculiarities of rainfall. {See Mapn, 
 pp. SO, (1)1 (7 72, 73.) These may be named as follows : 
 
 I. The E(piatorial Zone of Daily Rains. 
 
 This zone, like that of greatest heat, is north of the Equator, 
 its mean position being between latitude 1° and latitude 1U°. It is 
 shifted northward and southward with the seasonal changes in di- 
 rection of the sun. It nearly coincides with the zone of calms, 
 and is due to the meeting and ascent of the north and south trade- 
 winds. Throughout the forenoon, vapor is given off by the heated 
 
 waters, and continues to rise with the ascending air-currents. By 
 the middle of the afternoon, their height is such as to necessitate 
 precipitation. A heavy shower falls, interfering witli the air-cur- 
 rents. After two or three hours of rain, the upper atmosphere is 
 so warmed with the heat evolved by condensation that further pre- 
 cipitation is checked. The clouds are dissipated, and the rain-storm 
 is followed by a starlit night. 
 
 . The equatorial zone, though best defined over the ocean, may be 
 traced across the East Indies, Africa, and South Ameiica. The ascend- 
 ing air-ciu"rcnts retain their westward course, and their moisture is pre 
 cipitated far inland. Since this belt crosses its mean position twice a 
 year at intervals of six months, countries occupying this position have 
 two annual rainy seasons, occurring in April and October. 
 
 II. The Rainless Zones of Trade-Winds. 
 
 These, for reasons already indicated, are nearly rainless only 
 over the ocean. Then- limits are variable, depending on the posi- 
 tion of the sun ; and the mean position of each is encroached upon 
 by the equatorial zone of daily i-aius. The two rainy seasons, for 
 countries included in them, are hence separated by less than six 
 months, and indeed may in places become so closely connected as 
 to be regarded only as one. 
 
 Ascension Island is just beyond the southern limit of encroachment 
 by this efjuatorial zone, and hence has no rainy season. The rainless 
 zones-on the ocean extend to the neighborhood of latitude 25° south and 
 latitude 30° north. Even on land there are regular seasons of compara- 
 tive dryness prolonged several months. 
 
 III. The Snb-Tropical Zone of Rains. 
 
 This zone extends about 10° beyond the rainless zone. During 
 summer, the trade-winds encroach upon it, and but little rain 
 falls. In winter, variable winds occur, with correspondingly fre- 
 quent rains. 
 
 On passing from the ocean to the laud, this zone almost wholly dis- 
 appears, the countries included being visited with rain at all seasons, de- 
 tennined by local conditions. 
 
 IV. The Rainy Zones of Anti-Trade Winds. 
 
 These extend from latitude 40° onward toward the poles. The 
 prevailing Avind is from the southwest, bringing abundant rain 
 ujion western coasts, and comparative dryness on eastern coasts. 
 
 V. The Polar Zones of Summer Rains. 
 
 In winter, the winds blow outward in all directions from the 
 poles. They are cold and dry, hence the number of clear days is 
 greatest at this season. As soon as warmer winds from temperate 
 regions gain access, their moistiu'e is condensed into clouds that 
 rest on the ground or float at low heights. The cloudiness be- 
 comes greatest in summer, and often develops into drizzling rain. 
 The annual precipitation is chiefly in the form of snow. 
 
 Measnrenieiit of Rainfall. — The annual rainfall at any 
 place is measured by means of a rain-gauge — a graduated cylindri- 
 cal cup, deep enough to hold all the water that can fall into its 
 mouth during a single storm. It is usually ])rovided \yith a fun- 
 nel, which conveys the rain into a cylinder below. The area of 
 the mouth of the funnel must be carefully measured. If sufficient 
 rain falls to cover, to the depth of an inch, an area equal to that of 
 the funnel's mouth, this amount of rain is taken as the unit of 
 measurement. The sum of all the quantities thus registered dur- 
 ing a year is the annual rainfall. 
 
 Great care is exercised in selecting a position for the exposure of 
 a rain-gauge. It is gcnerall.v platted in an open space, about a foot 
 above the ground, where there can be uo interference with wind oi 
 rainfall. 
 
WEATHER OBSERVATIONS. — SNOW AND HAIL. 
 
 TABLE OF MEAN ANNUAL RAINFALL. 
 
 The following selections are made from a much larger table, published in the 
 "American Journal of Science" for January, 1882, by Professor Loomis. The name of 
 station, elevation in feet above sea-level, and annual rainfall in inches, are given: 
 
 STATION. 
 
 Height. 
 
 Ilainfall. 
 
 STATION. 
 
 Height. 
 
 Rainfall. 
 
 Cherrapoonjee, India. . . 
 Mahableshwur, India. . . 
 
 Caracas, Venezuela 
 
 Pernambuco, Brazil. . . . 
 Seathwaitc, England.. . . 
 
 London, England 
 
 St. Petersburg, Russia. . 
 
 Yakutsk, Siberia 
 
 Jerusalem, Palestine . . . 
 
 Home, Italy 
 
 Paris, France 
 
 Fort Tongas, Alaski. . . 
 Blockhouse, Oregon. . . . 
 
 Valdivia, Chile 
 
 Boston, Mass 
 
 4,125 
 4,540 
 2,730 
 
 1,334 
 
 10 
 
 299 
 
 2,500 
 
 "25 
 42 
 
 492.45 
 
 2.i3.24 
 
 155.37 
 
 106.07 
 
 152.24 
 
 24.57 
 
 17.67 
 
 9.00 
 
 18.83 
 
 30.91 
 
 20.08 
 
 118.3 
 
 96.29 
 
 115.49 
 
 41.44 
 
 New York, N. Y 
 
 Washington, D. C . . . 
 
 Charleston, S. C 
 
 Atl-anta, Ga 
 
 110 
 
 1,060 
 41 
 
 11,538 
 
 530 
 
 43.44 
 37.96 
 43.61 
 58.43 
 60.16 
 34.74 
 
 3.0 
 
 3.3 
 
 
 
 
 
 1.31 
 
 
 
 
 
 Baton Rouge, La 
 
 Chicago, in 
 
 Leh, Cashmere, Asia. . 
 Ascen.siou Island 
 
 Atacama, Bolivia 
 
 Cairo, E"'vpt 
 
 Thebes, Egypt 
 
 llourzouk, Sahara Des- 
 ert 
 
 
 Weather Observations.— Ttie study of the weather is now re- 
 duced to a science. Observations of the temperature, the moisture and 
 density of the air, the velocity and direction of the wind, etc., are simul- 
 taneously taken at different points in Europe and at over 500 stations 
 of the " Signal Service " in our own country. From reports of these, 
 telegraphed to Washington, charts are constructed, from which the 
 " weather indications " for twenty-four hours to come are announced 
 throughout the country in telegraphic bulletins. These bulletins are 
 valuable to the farmer as guides in liis operations ; while the cautionary 
 signals of approaching storms, displayed on the lakes and the Atlantic 
 seaboard, are of still greater service to the sailor. Even on the coasts of 
 Europe, vessels have been saved from disaster by telegraphic predictions 
 from the United States. (On the principles of weather- forecasting and 
 weather-charts, see pamphlet by Abercroniby, " Publications of British 
 Meteorological Council," No. 60.) 
 
 Questions. — Deline vapor, and show bow water is held in the air. What is 
 the source of atmospheric vapor ? Explain what is meant by the dew- 
 point; by absolute and relative humidity; by vapor-tension. What de- 
 termines the rate of evaporation ? In what way is evaporation measured ? 
 How is the distribution of vapor affected by elevation ? 
 
 Under what conditions, and in what forms, is the vapor of the air precipi- 
 tated ? Explain the phenomena of dew and frost; the effect of a cloudy 
 atmosphere on the deposit of dew ; of dense forests ; of high winds. 
 Illustrate the chilling effect of radiation. State the average annual de- 
 posit of dew. Show why ice sometimes forms during hot weather in calm, 
 clear nights. Account for the formation of sheet-ice ; of fog and clouds. 
 Describe what are popularly known as "dry fogs." Classify clouds. 
 Present the characteristics of cirrus clouds ; stratus clouds ; cumulus 
 clouds ; of other types derived by combination. Wliat can you say of 
 cloud- motion ? of cloud-tints ? How do clouds act as protectors ? What 
 determines the size of rain-drops ? 
 
 Specify the chief agents in the production of rain. Explain the effect of rain 
 on weather and climate ; the effects of winds, mountains, and vegetation, 
 on rainfall. Illustrate excessive and deficient rainfall. What is the 
 heaviest rainfall recorded ? State the general laws of rainfall. Into what 
 rain-zones has the earth's surface been divided ? What regions have con- 
 stant, periodical, or variable rains ? What becomes of the rain that falls 
 on the earth ? How do you account for the rainless region of Sahara ? 
 for the fertility of Egypt lying in the rainless region ? 
 
 If the atmosphere remained in a state of equilibrium for one year, how would 
 it affect the distribution of rain ? State the essential difference between 
 an insular and a continental climate. How does the climate of Alaska 
 differ from that of New York ? What part of South America receives 
 the most rain ? Of Asia ? Of Africa ? Compare New Guinea with 
 Greenland in regard to rainfall ; Ascension Island with Madagascar. 
 
 How far is weather periodical ? Explain the nature and value of weather 
 observations and prognostics. 
 
 SJVOW, SLEET, AJfD HAIL. 
 
 Snow. — "When the temperature of the air within which pre- 
 cipitation occui's is lower than the freezing-point of water, the 
 vapor is crystallized and falls in flakes of Snow. All snow-crystals 
 are formed on the same type, that of a six-pointed star, but vary 
 greatly in details of structure. A few of them are shown in the 
 figure. Snow-storms are rarely accompanied with very violent 
 wind, and seldom, if ever, with lightning and thunder. The as- 
 cent of the moist air from which snow is precipitated is hence 
 gentle, and such storms are charactei-istic of winter alone. 
 
 Snow-Crtstals observed by Captain Scoresby in the Arctic Regions. 
 
 When_part of the vapor is frozen into snow andthe rest con- 
 densed only into rain, the crystals in descending are washed to- 
 gether into ice-pellets, and the ground becomes covered with a 
 slippery coating of Sleet. It is not uncommon for the fall of snow 
 to change through that of sleet into a quiet rain-storm. 
 
 In certain regions the beautiful phenomenon of red snow is some- 
 times met with. Dr. Kane describes its color as deep, but not bright; a 
 handful thawed in a tumbler looked like muddy claret. The coloring- 
 matter he supposed to be either pollen or the bodies of animalcules. It 
 is due to the presence of a microscopic plant. 
 
 Hail is also a result of the freezing of aqueous vapor, but un- 
 der conditions that are comparatively exceptional. Hailstones are 
 ice-pellets which vary from 
 an eighth of an inch to two 
 or three inches in diameter. 
 They have been known to 
 become massed into granu 
 lated bodies nearly a foot 
 thick. The center of the 
 hailstone is usually a collec- 
 tion of little grains of ice 
 or snow imperfectly pressed 
 together. Around this nu- 
 cleus, successive shells of ice 
 are formed, often arranged so 
 
 as to present a radiated structure, with much air entangled within. 
 Occasionally they form clear masses without the snowy nucleus, 
 but containing each a small cavity full of compressed air. The 
 exterior is irregular, often pear-shaped, or flattened and jagged. 
 The force with which the largest hailstones fall is enough to kill 
 animals and inflict much damage upon vegetation and even 
 houses. 
 
 Forms of Hailstones. 
 (After various authorities.) 
 
THE SNOW-LINE. — GLACIERS. 
 
 83 
 
 Hailstorms occur most frequently during the warm season of the 
 year and tlie hottest part of the day; often in tropical or temperate, but 
 never in Arctic, r(><;ions. The central line of th(> area covered is gener- 
 ally free from hailstones, while two or more belts parallel to one another 
 are visited with an abundant fall. Lightning and thunder are almost 
 invariable accompaniments. These phenomena imply the rapid ascent 
 of saturated air, whit-h is spread out, according to the law of cyclones, 
 in the upper atnios])here, and cooled below the freezing-point at eleva- 
 tions mncli beyond that at wliich snow is commonly formed. A nucleus 
 of snow in its descent grows by contact with more vapor, which freezes 
 and imperfectly crystallizes into hail. Although the hailstone falls 
 through warm air, yet its size prevents it from melting before it reaches 
 the gromid. 
 
 A memorable hailstorm took place on July 18, 1788, traversing 
 Fi'ance and Holland, over a belt five hundi-ed miles in length. Upon a 
 central baud, ten or twelve miles wide, only heavy rain fell ; this marked 
 the vortex of the cyclone. On each side another band, from five to ten 
 miles wide, was violently pelted with hail, which caused the destruction 
 of property to the value of more than $5,000,000. Outside of these bands, 
 a heavy fall of rain extended over many miles. The storm lasted nine 
 hours. 
 
 Distribution of Snow.— What has been said in regard to 
 the distribution of rain applies equally to snow, if the temperature 
 l)e low. In tlie Arctic regions, drizzling rain falls tlirongh the 
 short summer season, but during most of the year the precipitation 
 is in the form of dry and powdery snow. In temperate regions, 
 where the atmospliere has more capacity for moisture, snow-storms 
 are Iieavier but less frequent. Nearer the Equator, no snow ever 
 falls at sea-level. The 
 intermediate limit sepa- 
 rating snowless regions 
 from those that are oc- 
 casionally visited is not 
 well delined; it is de- 
 termined by the same 
 conditions that fix the 
 winter isothermal lines. 
 The average number 
 of days each year on 
 which snow falls is, at 
 St. Petersburg, 171 ; 
 at New York, 17; at 
 . Cliarleston, 1. 
 
 The Snow-Line. 
 
 — But the mean tem- 
 perature falls with in- 
 crease of elevation as 
 well as of latitude, so 
 that even under the 
 Equator at the- height 
 of three miles the resi- 
 due of vapor that reach- 
 es that elevation is 
 precipitated as snow. 
 
 With increase of latitude the snow-line descends irregularly, so that 
 in the northern part of Greenland the region of perjjetual snow is 
 less than half a mile above sea-level, and at the poles it is still 
 lower. Amid the Alps, its hoifirht is about 1»,000 feet ; in Lapland, 
 ;i30n ; and at Beriiiir Island. 600. 
 
 The position of the snow-line is dependent upon the mean tem- 
 perature of summer rather than upon that of the whole year; upon 
 the proximity to the coast, the ex|30sure to moist winds, and the 
 quantity of snow that can fall at a single place. On the south side 
 
 of the Himalayas, exposeil to the moist winds from the Indian 
 Ocean, the lieight of this line is about 13, ((00 feet; on the north 
 side, facing the dry and lofty jilain of Thibet, it is 16,000 feet. 
 
 The total snow-fall at the summits of lofty mountains, such a.s the 
 topmost of the Himalayas and Andes, is lass than on their flanks, be- 
 cause tlie rarefied and cold air loses much of its capacity for aqueous 
 vapor. The most abundant snow-fall is at heights of less than 12.000 
 feet. The wind blows the di-y snow from the steep slopes into ravines 
 and valleys, so that often the tallest peaks remain nearly bare. 
 
 MuRrKKAl.>Cli GLACltK, GhI80NS AlI'S 
 
 (From a photograph.) 
 
 GLACIERS dJ^D ICEBERGS. 
 
 Glaciers. — Wherever large tracts of mountain-surface are ex- 
 posed above the snow-line, and the aimual precipitation exceeds 
 what can be carried off by melting and evaporation, the excess of 
 snow collects in the valleys ami moves gradually far below its usual 
 limit. Thus are formed rivers of solid water, called Glaciers. 
 
 Above the line where it falls even in summer, snow is soft and 
 powdery, accumulating on the slopes, drifting before the wind, and 
 covering the rocks with a sheet whose smooth surface reaches down 
 to the nearest valley below the snow-line. The warmth of the 
 summer sun melts the surface, so that the mass underneath becomes 
 more or less charged with watei-, which freezes at night. Groups 
 of feathery crystals are thus gradually compacted into granular 
 
 masses, while the sur- 
 face is furrowed by the 
 rills that are daily pro- 
 duced by renewed melt- 
 ing. The water can 
 not fill all the inter- 
 stices, so that the sun- 
 plowed snow-field only 
 becomes more roughly 
 granular below while 
 new accessions of dry, 
 white jiowder are re- 
 ceived above, and press 
 the compacted gran- 
 ules farther down. The 
 term nece is applied 
 to this mixture of clear 
 ice and porous snow. 
 
 With increase of 
 pressure, the nere pass- 
 es by insensible grada- 
 tions into glacier-ice, 
 which in mass appears 
 of a deep greenish-blue 
 tint, but at the surface 
 is always granulated 
 and white. At last the rigid stream reaches so far down that the 
 loss by heat balances the gain from the snow-fields that feed it, 
 and it ends in a rough wall of dirty ice, that arches over the surg- 
 ing M'aters of a turbid, milk-white stream. (On the formation of 
 glaciers, see Agassiz's ^'■Geological Sl'efe/ies," p. 208.) 
 
 Diineusions of Glaciers. — In Switzerland 400 glaciers, varying 
 in length froui five to fourteen nnlcs and in width from one half to one 
 mile, are foinid amid the Alpine valleys. Their greatest thickness is un- 
 known, but is estimated to exceed 1,000 feet. 
 
 The 51orter;itsch Glacier, easi- 
 ly accessible from the villages of 
 St. Moritz and Pontresina in the 
 lovely Engadine Valley, is one of a 
 numher issuing from the dazzling 
 neves of the grand Bernina chain of 
 mountains. It advances about sev- 
 en inches a year. Centuries ago, 
 chalets stood a mile farther up the 
 valley, and cattle fed on pastures 
 the relentless ice now claims for its 
 own. In the great floods of 1868, 
 the Jlorteratsch stream washed out 
 from beneath the ice fragments of 
 these ancient dwellings. 
 
84 
 
 GLACIER MOTION AND ITS THEORY. 
 
 The Alpine glaciers are insignificant in comparison with those of 
 Alaska and Greenland. The Muir Glacier, discovered in Alaska in 1886, 
 occupies an amphitheatre thirty or forty miles wide, from which nine 
 main ice-streams and seventeen branches unite to form a grand trunk that 
 abuts into the water of Glacier Bay in a wall 5,000 feet wide, and about 700 
 feet deep. {See "American Journal of Science," January, 1SS7.) The 
 Agassiz and Guyot Glaciei-s, on the flanks of Mount St- Elias, are hardly, 
 if at all, inferior to the Muir Glacier. In Greenland the glaciers are so 
 numerous and extensive that it is difficult to determine the limits that 
 separate them. The great Humboldt Glacier has a breadth of not less 
 than 115 miles, and its thickness is estimated to exceed 2,000 feet. Nor- 
 denskiold traveled 123 miles inland without discovering a limit to the 
 great ice-field before him; the whole of the interior of Greenland is 
 believed by Markham to be capped by an enormous glacier ever moving 
 toward the coast. (On the existing glaciers of the earth, consult Pro- 
 fessors Shaler and Davis^s " Glaciers," p. 8.) 
 
 Motion of Grlaciers. — The glacier creeps steadily down its 
 valley at a rate depending upon tlie supply from its snow-iields, 
 the slope of its bed, and the season of the year. The I'ate is much 
 faster in summer than in winter, at the middle than at the sides, 
 on top than beneath. Like a river of water, the glacier is retarded 
 where the friction is greatest, adapts its course to its bed, but 
 moves fastest along a line tliat is more croolved than the valley 
 which guides it. Upon the well-known Mer de Glace in Switzer- 
 land, Tyndall found the greatest motion in summer to be twenty 
 inches a day above Montanvert, and thirty-three inches a day 
 where the slope was steeper a short distance farther down. 
 
 In August, 1886, the daily marginal motion of the Muir Gla- 
 cier was ten feet, while that in the center was seventy feet. It 
 was, therefore, thrusting about five million cubic yards of ice each 
 day into the ocean. This rapid rate is due largely to the excep- 
 tional amount of precipitation in Alaska, where the annual rainfall 
 is about one hmidred inches, and the number of rainy days each 
 year often exceeds two hundred. (On the annual motion of gla- 
 ciers, see Forbes' s " Theory of Glaciers" jp. 133.) 
 
 Daily Loss of Glaciers. — At all times a glacier is losing 
 material by evaporation at its surface. The loss in summer is fur- 
 ther increased by melting. Rivulets are formed which cut their 
 way through the blue ice, and pools of water collect in surface de- 
 pressions and grow into miniature lakes. A lake was discovered 
 in 1842 on the Aar Glacier 206 feet deep and ten acres in extent, 
 with steep walls of ice over which rocks gradually tumbled as the 
 edges melted away. It lasted twenty-four years and traveled 600 
 feet on the glacier before it disaj^peared. Many lakes still larger 
 than this have been found on the glaciers of the Himalayas. 
 
 The variable ratio between gain and loss causes the lower end of the 
 glacier to vary in position. During a series of winters of greater sever- 
 ity than usual, the gain is more than can be balanced by summer melt- 
 ing. The extremity of the Mer de Glace thus advanced 258 feet during 
 one yeai", and 470 during another, into the. valley of Chamouni. At 
 present (1887) the summer melting is slightly in excess, so that most of 
 the Swiss glaciers are retreating, and have been for twenty years. 
 
 Glacial Moraines. — On each side of a moving glacier, rocks 
 and dirt are continually deposited from the mountain-slopes, and 
 are carried on to its lower extremity. Such piles of debris are 
 called lateral Moraines (broken stones). When two or more glacial 
 branches unite, each moraine continues on its own course, so that 
 long piles may be traced far oirt on the body of the main trunk. 
 At the lower end they are all deposited in roughly semicircular 
 heaps, varying in position with the advance or recession of the 
 glacier. The terminal moraine is often thousands of feet below 
 the snow-line, that of the Mer de Glace fuUy 5,000 feet. At the 
 
 foot of the neighboring Glacier de Bosson are houses and culti- 
 vated fields. 
 
 Glacial Streams. — The sti-eam of water issuing from be- 
 neath a glacier is derived partly from springs, partly from snrface- 
 melting, and partly from the melting due to friction at the bottom. 
 It carries in suspension the fine sediment pi'oduced by continual 
 grinding, so that the milky-white waters are recognizable aftei 
 flowing scores of miles. The Eiver Khone is thus white or cream- 
 colored until it empties into the Lake of Geneva. 
 
 Effects of Glacial Motion. — The slow, steady motion of 
 millions of tons of soUd ice over the rocky ground tends to grind 
 off rough edges, and score out shallow channels wherever resistance 
 is encountered. The difference in the rate of motion in different 
 parts of the glacier causes the brittle ma?s to become split into 
 thousands of cracks and crevasses extending down to inaccessible 
 depths. Into these the surface-streams jphmge and rocks fall. When 
 firmly imbedded in the ice at the bottom, the rocky masses become 
 the most powerful cutting engines known. There are instances of 
 bowlders lodged in cavities where the water and ice have rolled 
 them for ages against the walls, till all is rubbed smooth within 
 the " pot-hole." On larger masses, systems of parallel lines are 
 scratched ; and, where a ledge abruptly ends, a pile of much-worn 
 bowlders is found on its lower side. The traces of glacial action 
 in ancient times are thus alwaj^s easily recognizable. 
 
 At Lucerne, Switzerland, is a remarkable " Glacier Garden." It 
 contains many mai-ks of glacial action, including a number of pot-holes, 
 one of which is thu-ty feet deep and twenty feet in diameter. Several 
 subordinate cavities have been worn into the rock at the bottom, and in 
 the largest of them rests the rounded bowlder, many tons in weight, 
 that served as the glacial millstone. 
 
 Although the frozen surface of a pond or lake is nearly smooth, that 
 of a glacier is very far from being so. Ice-pinnacles and ruoraines 
 would atone be sufficient to make it rough. But this eifect is greatly 
 increased by the erosion of sm-f ace-streams, on the same principle by 
 which the land is worn into valleys. In adapting itself to its rocky bed 
 the glacier becomes much broken with fissures, producing ice-faults 
 whose walls show displacements many feet in depth, tilting usually for- 
 ward. Immense jagged blocks, separated by impassable chasms, jut out 
 in wild confusion. 
 
 Theory of Glacier Motion. — Hard, brittle, and stiff as ice 
 is, a horizontal bar of it, if supported at the ends, will slowly bend 
 into an inverted arch when a moderate weight is rested on it for 
 some time at the middle. Ice is, therefore, slightly viscous, like 
 pitch ; and a large mass of it, if strongly and gradually pressed, will 
 slowly change in shape. {Consult "AmeriGOfi Journal of Scieiice" 
 vol. v., p. 305.) 
 
 When water freezes, it crystallizes and hence expands. Wliat- 
 ever opposes this expansion tends to prevent freezing, or to pro- 
 mote melting if freezing has already occurred. When two masses 
 of ice are strongly pressed together, even though the temperature 
 be not -sensibly raised, there is melting at the surfaces in contact. 
 With relief of pressure the water thus formed immediately freezes 
 again, and the two masses are thus cemented together. This pro- 
 cess is called regelation. 
 
 Regelation may be illustrated by looping a piece of wire over a block 
 of ice supported at the ends, and attaching a weight of ten or fifteen 
 pounds. The wire cuts into the ice, which is melted under the pressure 
 thus applied. The water immediately freezes over the wii-e, where the 
 pressure Ls relieved. In this way the block is soon cut in two, but the 
 parts are cemented together at the same time. The support has been 
 severed without being weakened. (On regelation as a cause of glacier 
 motion, consult CrolVs ^'Discussions in Climate and Cosmology," p. 2Ji8.) 
 
IC'KDKUUS A Nil T II K 1 IJ 1" O H M A T I () N . 
 
 85 
 
 Like all otliur solids, ice rliaiiuvs in volume wlien its tempera- 
 ture is cliaiiu;<!il. I'u'low ;!2° Falir. it conti'acts by continued cool- 
 inu, ami at a rate tliat is faster tliau tlic rale of any known ruck or 
 metal, imleed neaily three times that of iron. Aiuonj^' the Alps, 
 at an elevation of 11,000 feet, the extremes of air temperatur(^ 
 in the month of Au- 
 Ljust liave lieen ascer- 
 tained to lie 59° F. 
 during' the tlay, and 
 14" F. durin;4' the 
 ni^ht. The radiation 
 at such hei;4hts is suf- 
 ficient to reduce tlie 
 temjierature of the 
 S1U1W to 0° F. at 
 times even in sum- 
 mer. 
 
 In consequence of 
 tliese changes of tem- 
 jierature, ice contracts 
 and expands to such 
 an extent that a mass 
 of it a mile in lenitth 
 would be made a foot 
 longer by a ri.se of 
 10° F. The force of 
 expansion is irresisti- 
 ble, and pushes the 
 lower part of the gla- 
 cier down the valley, 
 r.ut, if cooled 10° 
 F., and thus made to 
 contract, since gravity 
 prevents any portion 
 from moving np the 
 slope, the upper part 
 is pulled downwaril. 
 Motion thus due to 
 
 warnung and cooling is confined to the surface of the glacier 
 where radiation is free, and to the steep slopes where the ndvd 
 is thin. 
 
 Aside from motion due to variation in temperature, every glacier 
 is thrust steadily downward by the pressure of ice and snow at the 
 top of the snow-fleld. Pressure causes melting, and this is followed by 
 regelation of the water, some of which passes stiU farther down. 
 Pressed over a projection in the valley, the mass splits from the top, and 
 tilts forward. The portion Ijchind it, thus lo.sing its prop in ft-ont, soon 
 yields to the pressure in its rear, topjdes over, and is cemented by regela- 
 tion to that before it. The summer sun melts the surface-ice ; streams of 
 water wash through the crevices and widen them, and every part is con- 
 tinually settling obliquely downward, yielding always in the direction 
 of least resistance, opening in cracks which are then closed by regelation, 
 and thus creeping far below the snow-line. 
 
 The ice by gently bending, erushiug and melting imder pi'es.sure, 
 snapping under tension, slitUng and toppling over rocks, cementing by 
 regelation, acts like a stiff viscous fluid. It spreads out where the vaUey 
 is broad, and is squeezed through naiTow goi-ges, changing its rate like 
 a river, according to the width and slope of its bed. Wherever the 
 pressm-e is strongest the granular nuxture by melting and regelation 
 loses much of the air that had lieen entangled in the snow, and becomes 
 compacted into clear blue veins of nearly solid glacier-ice. These are 
 pressed downward farthest in the middle, and are crossed by crevasses 
 due to the stretching force exerted by the central parts upon the mar- 
 
 Fl-OATING BEKG. 
 
 ginal portions. Thus the river of ice moves sluggishly on till it is 
 arrested far down the valley. Here it gives birth to a river of water 
 that loses itself at last in the ocean, is lifted up as vapor into the air, 
 to be wafted back in clouds to the mountain-toiis, there to be con- 
 densed as snow, and to renew its ceaseless round in the great circulation 
 of Nature. (Cunsiill I'riifeasor TijiidiilVs " Ol/iciers nf ihe Aljis") 
 
 Iceber}>:s. — In tlie, jiohir 
 regions, glaciers extend down- 
 ward into the sea, and are 
 pushed out until portions arc 
 undei-uiined liy tlie action of the 
 waves and currents, and lie</ome 
 detached. In some cases this is 
 done gradually and ([uic'tly ; in 
 others the separation of gigantic 
 masses of ice, tojjpliug into the 
 water, is accompanied with de- 
 tonations like thunder. These 
 mas-ses are floated off as Icebergs 
 into temperate regions, where 
 they are melted in the warm 
 waters of the great currents from 
 the tropics. 
 
 Immense masses of field-iec ac- 
 cumulated along the shores, even 
 where glaciers are absent, become 
 detached in like manner and are 
 floated away. The crew of a 
 wrecked vessel was once drifted 
 1,300 mdes on one of these great 
 ice-floes. 
 
 Size and A ppejirjiiice of Icebergs. — The majority of 
 icebergs from the Arctic regions do not rise more than 50 or 100 
 feet above the .surface of the water. Occasionally one is seen that 
 exceeds live hundred feet in height. If thrown off by a glacier, 
 its surface is rough and ragged, and sometimes scattered over with 
 bowlders, the evidences of moraines. Tlie white glacier-ice is 
 melted by tlie sun, leaving minarets, towers, and grottoes, through 
 which the light is broken into rainbow hues. A grand .spectacle, 
 but one full of danger to the nuiriner, is a fleet of bergs, with their 
 picturesque cliffs and peaks, moving on slowly liut with resistless 
 momentum among floes and fields of ice. 
 
 Carryiiigf-PoAvei" of Icebergs. — Pure water is den.sest at 
 ;'>9.2° F. Expanding as it freezes, pure ice is but little more than 
 nine-tenths as dense. With salt in solution, the freezing-point is 
 lowered and the density increased. A cubic foot of jJure ice weighs 
 fifty-seven and a half pounds ; the same volume of sea-water weighs 
 sixty-four pounds ; both being measured at S2° F. Glacier-ice 
 with its entangled air, is still lighter than pure ice, so that about 
 one-sixth or one-seventh of the whole mass is exposed and the rest 
 submerged. An iceberg a mile long, half a mile wide, and five 
 hundred feet deep, would hence be capable of carrying over twenty 
 million tons of rock. Large bowdders are thus transported many 
 hundreds of miles and deposited on tlie bed of the ocean, as the 
 ice grradually melts. 
 
 Antarctic Icebergs. — It is in the Antarctic regions that 
 by far the largest icebergs liave been seen. These rarely pre- 
 sent the evidences of being broken from glaciers, but are for the 
 most part flat-topped, with vertical sides, which on examination 
 
86 
 
 ATMOSPHERIC ELECTRICITY. 
 
 eliow a series of layers, made up alternately of blue ice and wliite 
 compacted snow. Each layer is thought to represent the snow-fall 
 of a year, so that these icebergs are the deposits of centuries. 
 Some have been seen several miles in length, and as much as 900 
 or 1,000 feet high. 
 
 Making allowance for a submei-gcd part six times as great, ice- 
 bergs a mile in vertical thickness are not uncommon in these waters. 
 Mr. Croll estimates the thickness of ice accumulated at the South 
 Pole to be not less than seven miles. Exposed land is here a rarity. 
 The Antarctic Continent and waters are alike covered with an ice- 
 cap, from whose edges the supply of icebergs is exhaustless. {Con- 
 sult article on '■'■The Antarctic Ocean^'' in '■'■ Pojiular Science 
 Ilonthly'''' for September, 1SS6.) 
 
 Questions. — Under what conditions does snow fall ? Hail ? Describe snow- 
 crystals ; hailstones. Exjjlain the phenomenon of red snow. At what 
 season of the year, and why, are hailstorms prevalent ? What can you 
 say of the annual snow-fall in different jiarts of the globe ? Of the snow- 
 line ? Of the snow-fall on the summits and slopes of mountains ? Wliy 
 is the snow-line higher in the Penivian Andes than at the Equator ? 
 
 Trace the history of a glacier from the fall of snow on the mountain above to 
 the melting of the ice in a valley or in the sea. Give some idea of the 
 size of Alpine, Greenland, and Alaskan glaciers. Account for glacial 
 motion. What effects are referable to glacial motion ? Describe mo- 
 raines; glacial streams. Explain regelation. 
 
 Describe icebergs, and illustrate their formation and their carrying-power. 
 What can you say of the course of icebergs from Arctic waters ? of Ant- 
 arctic icebergs ? What effect on our climate have floating bergs ? 
 
 ATMOSPHERIC ELECTRICITY. 
 
 Sources. — Under certain conditions, electricity may be gen- 
 erated artificially by the expenditure of some kind of energy, such 
 as friction, or the motion of magnets, or chemical energy. Its na- 
 ture is not clearly defined, but many of its laws are well understood. 
 It is continually manifested in the atmosphere ; but the sources of 
 atmospheric electricity are not known. The friction of moving 
 masses of air is supposed to have some effect in electrifying the 
 atmosphere. When an area of high atmospheric pressure en- 
 croaches upon one of low pressure, the air invariably shows higher 
 electrification. 
 
 Definition of Terms. — A body is said to be electrified 
 positively or negatively, according to the quality of its charge. If 
 strongly charged positively, it is said to be at high potential; if 
 negatively, at low potential. Bodies oppositely electrified attract 
 each other, and if brought near enough each becomes discharged 
 at the expense of the other. Discharge is usually accompanied 
 with the appearance of heat and light, as when a spark is obtained 
 from an electrical machine, or when lightning flashes in the sky. 
 Under proper conditions it is often possible to secui-e discharge 
 without these manifestations. If the opposite charges are equal, 
 the bodies when discharged are brought to 2ero potential. 
 
 Measurement of Electricity. — Electricity, though not a 
 fluid, may be measured like a fluid. Just as we express the height 
 of a waterfall in feet, we may measure the height of electric poten- 
 tial in units called volts. Thus the fall of potential produced by 
 the change of electrical energy into heat and light in an average 
 electric arc-lamp is about forty-six volts. If a piece of zinc and a 
 piece of copper be dipped together into a certain mixture of acid 
 and water that acts chemically on the zinc, the diiference of poten- 
 tial between the two plates is about one volt. 
 
 Electrical Condition of the Atmosphere. — In fair 
 weather, the atmosphere is nearly always electrified positively; 
 slightly at the ground, and much more strongly at great elevations. 
 A fine stream of water-drops falling through the air becomes elec- 
 trified like it, and, if caught by means of approjiriate instruments, 
 the potential of the air may be measured in volts. In this way it 
 has been found that its electrical condition is always variable, but 
 particularly so when a storm occurs. Just before a gentle rain- 
 storm the potential usually falls, often becoming strongly negative. 
 During a violent storm, it alternates from positive to negative with 
 great rapidity and through a wide range. 
 
 Thunder-storms. — Dry air is a poor conductor of elec- 
 tricity, but may be electrified uniformly throughout its mass. 
 Water-vapor is a good conductor, but upon electrified masses of 
 solid or liquid the charge is confined to the surface. Particles of 
 vapor, becoming electrified like the air in which they float, are 
 cooled on ascending; and many such particles become condensed 
 together into a visible drop, whose surface is much less in propor- 
 tion to its mass than when divided up as vapor. The potential of 
 the drop is, therefore, much greater than before condensation. A 
 dense cloud thus becomes strongly electrified, positively or nega- 
 tively, according to the condition of the au- from which its vapor 
 came. 
 
 If two such clouds with opposite charges approach each other, 
 discharge may take place through the intervening air as a stroke of 
 lightning. The sudden heating of the air by this immense spark 
 causes it to exjjand and immediately collapse. The impulse is 
 transmitted from successive parts of the spark in a series of air- 
 waves, producing the sound of thunder, which continues to roll, 
 as if from many sources, because the sound is reflected many times 
 from houses, hills, and mountains, from clouds, and from masses 
 of air differing among themselves in density. 
 
 If a charged cloud approaches the ground instead of anothei 
 cloud, discharge may take place between it and the earth. The 
 lightning in transmission seeks the best conductor, and thus ex- 
 posed objects, such as tall trees or houses, ai"e apt to be included in 
 its path, with disastrous effect. 
 
 The potential to which a cloud may be charged in summer, when 
 the conditions are such as to produce exceedingly rapid condensation, is 
 incomparably higher than any that can be attained by artificial means. 
 The longest spark ever produced in a laboratoi'y was less than four feet 
 in length. Strokes of lightning several miles in length have been often 
 seen. The potential needed to produce a spark one mile in length has 
 been estimated to exceed a thousand millions of volts in dry air. 
 
 The explanation of thunder-storms just given is believed to be the 
 most probable. No certain knowledge is possessed on this subject. 
 
 The Aurora is a luminous appearance believed to be of elec- 
 trical origin. Because first seen only in the northern skies, the 
 name Aurora Borealis, or Northern Lights, was formerly applied 
 to the phenomenon ; but its manifestation is quite as frequent and 
 conspicuous in the Antarctic regions. 
 
 The sky becomes at first banded with faint, whitish light, which 
 settles into an arch that spans the northern heavens. Beneath this 
 is an unilluminated area that seems unusually dark by contrast. 
 Beams and streamers, most of which are white, passing into yel- 
 low, red, and pui-ple, radiate upward, as if from a center, under 
 the arch, and appear to converge toward a point opposite, high 
 in the southern heavens. A line drawn in space from this point 
 to that from which they radiate below the horizon, has the direc- 
 tion of the magnetic line of force along which the dipping-needle 
 is directed at the place of observation. 
 
THE AURORA. — OPTICAL PHENOMENA. 
 
 87 
 
 At the Equator, tlic aurora is unknown; it is probably never seen 
 within the tropics, and up to latitude 40° north it is rare. The region of 
 ffi-eatest fi-equency is a belt, roughly oval in shape, inc-losing the polar 
 regions. On the Continent of Europe and Asia, this belt is about tlu'ee 
 or four degrees wide, and embraces the most northern j)art.s of Norway, 
 Sweden, Russia, and Siberia. Crossing the Atlantic, it extends farther 
 south, and on the American Continent it includes much of Labrador and 
 Hudst)n Bay. Its course beai-s some general resemblance to that of the 
 nearest line of equal magnetic dip. (See Chart, p. 9.) 
 
 Over its area, eighty or one hundred auroras are displayed annually, 
 those seen from its inner or polar side appearing south of the observer. 
 The center from which these ilisplays appear to radiate seenjs thus to have 
 some connection with the magnetic pole. But the belt is not constant 
 in ])osition ; it swings with the seasons, reaching its most southern line 
 at the time of each equinox, and traveling back farthest north in both 
 summer and winter. In the United States, auroras are most frequent 
 iu April and September. 
 
 Electrical Character of the Aurora. — While the Au- 
 rora is not yet fully understood, all observatiou.s point to the con- 
 clusion that it may be referred to electrical discharge in the upper 
 and thinner portions of the atmosphere. The height at whicli the 
 glow begins to be visible has no fi.xed limit except such as may 
 be determined by the density and humidity of the atmosphere. 
 (On polar light, or the Aurora, consult JVordensHold's '•The 
 Voyage of the Vega,^^ p. 35.) 
 
 If a series of electric sparks be passed through air that is gradually 
 made thinner, the changes in appearance are very characteristic. In 
 dry air of ordinary density, an electrified body retains its charge for a 
 long time ; but in a vacuum, the charge becomes rapidly lost. In like 
 manner, a large body of air charged to high potential would quietly 
 lose its charge by diffusion upward, if not discharged near the groimd 
 as in a thunder-storm. A spark that can not leap across more than half 
 an inch of ordixiary air passes easily through eight or ten feet of au' 
 whose density is diminished to one thi-ee-hundredth, and becomes then 
 diffused, rosy, and stratified in bands. When the air is rarefied to the 
 same degree that obtains at the height of fifteen miles, the electric dis- 
 chai'ge through it assumes the carmine tint so characteristic of the finest 
 auroral displays. 
 
 AVe have seen that the average bai'ometric pressure over the 
 interior of a great continent is high in winter and low in summer, 
 and that the change from one of these conditions to the other at 
 tlie time of the equinoxes is accompanied witli disturbances, such 
 as storms, which are always preceded by a highly electrified condi- 
 tion of the atmosphere. When precipitation is rapid enough to 
 produce dense clouds and rain, discharge occurs through the me- 
 dium of lightning. This is the most common metliod within the 
 tropics. But quiet discharge may also occur, between the earth 
 and upper atmo.sphere, or between various portions of tlie atmos- 
 phere itself. There is rea.son to believe tliat the luminous bands 
 are within ten miles of the earth. Lightning attends cumulus 
 clouds ; the aurora may attend cirrus or stratus clouds and haze. 
 
 The aurora is most frequent in high latitudes. Even more common 
 than lightning or the aurora in middle latitudes is a phosphorescent ap- 
 pearance of the clouds, due to the silent discharge of electricity between 
 their component particles. (Consult Report of the Chief Signal-Officer 
 for 1876, pp. 309, 310.) 
 
 Avu'oral displays are nearly always accompanied with marked dis- 
 turbances in the electrical condition of the ground as well as of the air. 
 Earth-currents become strong enough to interfei'e seriously with the 
 business of telegraph-lines. They cause the magnetic needle to sway 
 from side to side, so that the direction of "magnetic north" becomes 
 variable for hours together. To what extent the magnetism of the earth 
 may be connected with the mean electrical condition of the atmosphere 
 is yet unknown. {Consult ^' Signal-Serrice Notes," No. XVIII., mi 
 " The Aurora, in its Relations to Meteorology,"' by Alexander McAdie.) 
 
 OPTICAL PHE,KOMEMA. 
 
 Most of the Optical Plieiioinciia of the atmosphere, aside 
 from those already discussed incidentally, can be satisfactorily ex- 
 plained only with the use of matliematical symbols that would be 
 inajjpi'opriate in the present volume. 
 
 Whenever light passes from one medium into another, some is 
 absorbed and changed into energy of different wave-lengtli, ceasing 
 therefore to be manifested as light. Tlie rest has its direction 
 altered, part being reflected and part transmitted. If the second 
 medium be denser than the first, the light is retarded, and hence 
 bent toward the perpendicular erected at the point where it strikee. 
 
 .Nt.Ui TUE Sl'KZ ("AN.II,. 
 
 Looming and Mirage. — In the Arctic regions, when the 
 air is calm, the layer in contact witli the cold ground or water may 
 become cooler and denser than that at a moderate height. Kays 
 of light from distant oljjects below the horizon are bent slightly 
 downward, so that, like the morning or evening sun, such objects 
 appear above their true positions. Often they seem distorted or 
 rougliiy magnified on account of irregularities in the density of the 
 lower air. This apparent elevation of distant objects is called 
 Looming. Though best seen in the Arctic regions, it may be no- 
 ticed at sea in all parts of the world when the air is calm and 
 warmer than the water below, and it sometimes occurs on land. 
 
 Mirage iin^rahzh') is explained on the same general principle 
 as looming. On the burning sands of the Sahara, the lowest layers 
 of air are decidedly warmer and rarer than those a few feet above 
 the ground. Eays coming obli(juely down from tall objects near 
 the horizon are hence bent slightl}' upward and totally reflected 
 from the lower thin mediiim, as if from a mirror. 
 
 An educated surveyor once reported the existence of a large inland 
 lake in the desert region of Australia. On examination, it proved to be 
 only mirage. 
 
 (For the explanation of rainbows, of coronas and halos around the 
 moon, and of " mock suns " and " mock moons," the student is referred 
 to Lackland's " Meteoi-s and Atmospheric Phenomena.") 
 
 Questions. — Mention the sources of atmospheric electricity. What is meant 
 by liigli ])otential ? Low potential ? Describe the process of measuring 
 electricity. What can you say of the general electrical condition of the 
 atmos])here ? Explain the phenomena of thunder-storms. 
 
 What is the Aurora Borealis ? Where is it manifested, and how is it ac- 
 counted for ? Where is it unknown ? Detine the belt of greatest aurora- 
 frequency. Is this belt constant in ])osition ? By what disturbances are 
 auroral displays accompanied ? Explain looming and mirage. 
 
PLANT-LIFE ON THE EARTH. 
 
 It is the Province of Physical Geography, not only 
 to present a luminous picture of the earth's surface features, its 
 ocean-waters and their movements, its rivers and lakes ; to investi- 
 f^ate the nature of the atmosphere with its system of circulation, of 
 weather, and of climate — but also to inquire into the character and 
 distribution of life on the globe, and to explain the relation be- 
 tween it and the inorganic world. 
 
 Another class of phenomena, therefore, now claims our atten- 
 tion — those connected with Organized Bodies — bodies which are 
 endowed with vitality, and generally possess organs on the action 
 of which their growth and development depend. The Organic 
 World consists of plants and animals. Collectively these are often 
 designated as the Vegetable and the Animal Kingdom. 
 
 The Organic World differs from the Inorganic in several 
 important respects, other than its existence by virtue of life. These 
 may be briefly summarized as follows : 
 
 Organized Bodies Unorganized Bodies 
 
 consist mainly of the four chemical may contain any of the sixty - five 
 
 elements, carbon, hydrogen, oxygen, known chemical elements; can only 
 
 and nitrogen; grow by the assimila- increase in size by accretion of matter 
 
 tion of nutritious matter, and its di- on their surfaces ; are either of no 
 
 gestion in their interior cavities ; are of definite form, or are crystalline ; as, 
 
 definite forms, bounded by curved lines for example, salt, 
 and sm-faces ; as, for example, a shell. 
 
 Plants, considered collectively, are less complex in organi- 
 zation than animals. They grow directly from inorganic matter 
 which they assimilate, and transform into food for animals ; thus 
 they occupy an intermediate position in the economy of nature. 
 While between tiie higher developments of the animal and vpgeta- 
 ble kingdoms there are very manifest differences, the most simply 
 organized plants so closely resemble the lowest forms of animal 
 hfe that it is difficult to decide to which kingdom they more prop- 
 erly belong. There are, however, some nearly constant differences 
 between the two, which may thus be briefly expressed : 
 
 Plants Animals 
 in chemical composition contain more in chemical composition contain more 
 carbon ; obtain their food from the nitrogen ; obtain their food directly 
 mineral kingdom ; inhale carbonic acid or indirectly from the vegetable king- 
 from the atmosphere, and exhale oxy- dom ; inhale oxygen and exhale car- 
 gen in sunlight. bonic acid under all conditions. 
 
 STRUCTURAL ELEMEKTS OF PLJJVTS. 
 
 Botany (from a Greek word meaning hsrh) is the science of 
 plant-life in its broadest sense. While in the study of Physical 
 Geography we have mainly to consider the geographical distribu- 
 tion of plants, we may also with propriety briefly discuss their 
 structure, their classifieation, and the phenomena of their growth 
 and multiplication. 
 
 Structure of Plants.— All that is known of the minute 
 structm-e of plants has been learned with the aid of the microscope. 
 This instrument shows that every portion of each vegetable organ 
 consists of an immense number of minute and regularly formed 
 cavities, called Cells. The walls of the cells vary greatly in thick- 
 ness in different parts of the structure, and the cells themselves are 
 of many different forms and dimensions. Cell-walls form the per- 
 manent parts of all plants, and tlie substance composing them is 
 
 In the engraving, Fig. 1 represents cells from the 
 pith of the sunflower ; Fig. 2, wood-cells of the chest- 
 nut ; Fig. 3, cedar-cells ; Fig. 4, an annular, or ring- 
 shaped, cell from the sunflower-stem ; Fig. 5, a spi- 
 rally marked cell from the same — all magnified one 
 hundred times. 
 
 called cellulose in the softer tissues and lignin in the woody por- 
 tions. {Compare Goodale^s ^^Physiological Botany" p. '25.) 
 
 Cells are in general 
 ^ , very small, and only in 
 
 rare cases can they be 
 seen with the vmaided 
 eye. The minute struct- 
 ure of the smaller and 
 simpler plants may be 
 studied du-ectly under 
 the microscope on slips 
 of glass prepared for 
 the purpose ; but the 
 denser tissues must be 
 cut m. very thin sections 
 with a sharp knife be- 
 fore they can thus be 
 examined. The study of 
 plant-tissues is known 
 as Histology. {Consult 
 Behrens's ^'■The Micro- 
 scope in Botany.''^) 
 
 Classification of Plants. — More than 150,000 different 
 species of plants have been described by botanists ; new species are 
 constantly being discovered. Those now known may be grouped 
 in five subkingdoms, as follows : — 
 
 I. Protoi>hy'ta (from two Greek words meaning Jl?'st plants 
 — the lowest order), the most simply organized and smallest plants, 
 including baete'ria {staff -like forms), and yeast or ferments. These 
 are very minute, and consist either of a single cell or of loosely 
 aggregated rows or grotips of cells, which multijsly mainly bj 
 splitting in two, or by a budding of new cells from the old. 
 
 • The bacteria 
 cause the putrefac- 
 tion of organic mat- 
 ter, and are always 
 characteristic of 
 contagious maladies 
 in man and other 
 animals. It is be- 
 lieved that they are 
 the active agents 
 in the production 
 of many diseases. 
 Yeast causes the fer- 
 mentation of sugary 
 solutions with the 
 production of alco- 
 hol and carbonic- 
 acid, contrary to 
 the action of most 
 plants, which in- 
 hale this gas. {See 
 Grove's '■'■Bacteria 
 and Yeast Fungi."} 
 
 II. Thal'lophyta, plants in which there is no well-marked 
 distinction between stem and leaves, these being merged in a flat 
 tened or fiiiely divided structure called a thallns {young shoot). 
 Under this subkingdom are classed the sea-weeds or algse {al-jay), 
 the fungi {fun'ji), and the lichens {li'kens). These are mainly re 
 produced by spores, cells of small size which perform the ofSce of 
 seeds in the more highly organized plants. The simplest of the 
 thallophytes ai'e plants of single cells or rows of cells, whose walls 
 
 Fig. 1 is the yeast-plant ; at a and b the process of 
 budding, by which new cells are formed, is shown. F'ig. 3 
 represents spiral bacteria ; Kg. 2, the bacterium of the 
 disease consumption, known as Bacillv^ tuberculosis; Fig. 
 4, a group of small globular bacteria, called Mio'omcci 
 (small kernels) — all highly magnified. 
 
CLASSIFICATION OF PLANTS. 
 
 89 
 
 are often beautifully marked, the cells themselves being of many 
 curious shapes. These plants are larger than the protophytes, and 
 diifer from them also in other respects. 
 
 Among the minute algre are the groups called di' atoms (cut in 
 two) and desmids ((■hain-fonus), characterized by their sj'nHnctry. 
 
 Diatoms and Desotds. 
 
 The figure illustrates some of those lowly thallophytes. Ou the left is a group of 
 diatoms, showing eircular, triangular, hexagonal, and elongated forms, with tlie wonder- 
 fully regular and beautiful markings ou the eell-walls. The walls are in these plants 
 largely composed of silica; they make up the material known as tripoli or electro- 
 silicon, used as a polishing powder, as well as in the manufacture of the explosive, d)»- 
 namite. In the figure to the right, is one of the jointed organisms called osfiUaloria, 
 from its wavy movement in the water. The rest arc desmids. 
 
 Tlie larger algaj are the common sea-weeds found on the ocean- 
 beach at low tide. The fungi include mushrooms, toadstools, puii'- 
 balls, molds, etc. ; a white fungus attacks certain species of fish, spread- 
 ing over their bodies with fatal consequences. The lichens grow 
 
 on dry rocks, on tniuks 
 and branches of trees, on 
 fences, and on the ground. 
 They are very long-lived. 
 
 III. Bryophy'ta 
 
 (moss-like pla7its), com- 
 prising the bog-mosses, the 
 true mosses, and the liver- 
 worts ; mostly furnished 
 with stems which bear dis- 
 tinct, small leaves. They 
 are reproduced by spores, 
 which are borne in con- 
 ceptacles. 
 
 Most bryophyta grow on 
 the ground in damp or wet 
 places, or on trees and rocks ; 
 a few of the mosses thrive in 
 fresh water, but no members 
 of this family are marine. 
 
 
 Illustuations of Alce, Lichkns, and Fungi. 
 
 In the illustration, Fig. 1 is the common sea- 
 lettuce ; Fig. 2, a branch of the rocU-wced, with 
 the conceptacles which contain tlic spores shown 
 at a, and the floats which support it in the water 
 at b ; Fig. 3 is a small fragment of a mold, with 
 its rows of spores at the top, greatly magnified ; 
 Fig. 4, a mushroom, with the spores on the r/Vls, 
 under the cap ; Fig. 6 represents a lichen, com- 
 monly found drooping from dead branches in the 
 woods ; Fig. 6, another lichen, which also grows 
 on trees in flat patches of a .gray color, the spores 
 being found in the spots on its surface. 
 
 IV. Ptei-'idophyta 
 
 (fern-like plants) include 
 tlie true ferns and their al- 
 lies, the club-mosses, and 
 horse-tail rushes. These 
 are among the most beau- 
 tiful and interesting of all 
 plants. They are also re- 
 produced l)y spores, which 
 in the ferns are generally 
 boi'ue on the under sur- 
 
 Illustrations of Mosses and Liverworts. 
 
 Fig. 1 is a common wood-moss ; in Fig. 5, h shows the spore-bearing conceptacle, 
 and a the same covered with its hood. Fig. 2 is a branch of a bog-inoss ; the round 
 bodies at the top contain the spores, and one of these further enlarged is shown in Fig. 
 6, with its lid detached. Figs. 3 and 4 are liverworts, plants intermediate in aspect 
 between the lichens and mosses. 
 
 faces of the leaves, and in the other groups on specially modified 
 branches. Pteridophytes grow on the ground, as well as on rocks 
 and trees. 
 
 V. Phan'ero|?aniia 
 
 (from two Greek words, im- 
 plying, botanically, with visi- 
 ble foiveri)) include all the true 
 dowering plants, such as roses, 
 pines, and lilies. Their organs 
 are of two kinds — vegetative 
 organ s, devoted to the growth 
 and development of the plant 
 itself, comprising the root, 
 stem, and leaves ; and repro- 
 ductive organs, the Hower, 
 fruit, and seed. 
 
 Organs. — The Root, 
 generally buried in the soil, is 
 the organ which absorbs inor- 
 ganic matter from the earth. 
 It is fibrous in grasses, fleshy 
 in the turnip and sweet-pota- 
 to, and woody in all trees and 
 shrubs. 
 
 The Stem rises from the 
 root and supports the leaves 
 and reproductive organs. It 
 is herbaceous when soft in 
 texture and lasting only one 
 or two years, and woody in 
 trees and shrubs. 
 
 RockFern, Equsetcm, and Clcb-Moss. 
 
 In the engraving, Fig. 1 is the common 
 rock-fern ; at «, ft, and c^ are shown the posi- 
 tions of spores on the lower surfaces of vari- 
 ous fern-leaves, a, in round spots, 6, in elon- 
 gated ones, and c along the edges. Fig. 2 
 is a piece of a horse-tail rush {eguue'tnm), 
 with the spores borne at the top ; Fig. 3 is 
 a club-moss, the coramim trailing Christinas 
 green. 
 
90 
 
 FLORAL ORGANS. — EXOGENS AND ENDOGENS. 
 
 ?LOKAL Organs. 
 Fig. 1 represents a section through 
 a flower ; d is the calyx, c the corolla, 
 a and b the essential organs. Fig. 2 
 is a plan of the same flower. 
 
 The Leaves are the orsrans which inliale most of the carbonic 
 acid from the atmosphere, and transform it together with the sap 
 
 into celhilose and other substances. 
 / " The breathiug-oriiiees {stomata) are 
 
 mainly on the i;nder sides of leaves, 
 and open into air-chambers in the 
 cellular tissue. They are minute 
 and extremely numerous, 120,000 
 having been counted in a square 
 inch of surface. Tlieir function is 
 to maintain a circulation between 
 the cells of the interior of the leaf 
 and the outer air. 
 
 The Flower, when complete, 
 consists of two external portions 
 called floral e7ivelo])es, designed in 
 pai-t for protection ; and an inte- 
 rior set of essential organs, db-ect- 
 ly concerned in seed-production. 
 
 The floral envelopes are the calyx 
 (ill Latin, a cup), consisting of distinct 
 or coaleseent se'pals ; and the corolla 
 (in Latm, a little crown), composed 
 of leaves called pet'als, delicately or 
 brilliantly tinted in many blossoms. 
 The essential organs are the sta'mens and pistils. In the accom- 
 pauyiug figure a is a stamen, and b a pistil. The sfeimen consists of a 
 stalk or filament, on which is borne a sac constituting the anther, filled 
 with a dust-Uke substance known as pollen. 
 The pistil is a straight shaft (style), dilated at 
 its summit into a glutinous body called the 
 stigma and expanded at its base into a cav- 
 ity, the ovary, containing the ovules or bodies 
 which are to become seeds (shown at/). The 
 antbei-s, when mature, discbarge granules of 
 pollen ; these are engaged by the stigma, de- 
 scend through the tissues of the pistil, and fer- 
 tilize the ovule, which develops, as the petals 
 and essential organs wither, into the seed or 
 embryo plant. {See Professor GoodaWs ^^The 
 Wild Floivers of America," p. 6.) 
 
 The process of plant-generation is materi- 
 ally aided by insects which, in tbeh- search for 
 the nectar, become covered with pollen, and 
 so convey the fructifying principles from blos- 
 som to blossom. In some species, fertilization 
 could not be effected without aid of this nature. 
 (On bees and flowers, cmisult BucMey's " The 
 Fairy-Land of Science," p. 212.) 
 
 In certain parts of the world, humming- 
 birds are useful auxiUaries in the transporta- 
 tion of pollen ; while the hand of man not 
 infrequently intervenes to practice artificial 
 fecundation. 
 
 Forms of Stamens and 
 Pistils. 
 
 In Fig. 1, both ai 
 shown together ; Fig. '. 
 stamens ; Fig. 3, pistils- 
 Figs. 2 and 3 magnified. 
 
 The Truit is the ripened ovary. The Seeds are the ripened 
 ovules ; they contain germs, where the life of the plant is concen- 
 trated. (On fruits 
 and seeds, consult 
 Figuier's " The 
 VegetaUe World.;' 
 pp. 156-176.) 
 
 The Phanero- 
 gamia are of two 
 
 Cross and Vertical Sections of Endogenous Stem 
 (Palm-Wood). 
 
 classes, viz., An- 
 giosperms (an'je-o- 
 
 sperms) (from, two Greek words meaning seed-vessels), with closed 
 ovaries ; and Gym'nosperms (having naked seeds), with ovaries 
 open, and ovules and seeds thus exposed to the air. To the latter 
 class belong the pines, firs, and giant-trees of California. 
 
 The AngiospeiTus are further divided into 
 two sub-classes, distinguished by the structure of 
 the stem — Endogens, which increase the diameter 
 of the stem by growth from within (the grasses, 
 palms, orchids, lilies) ; and Exogens, which in- 
 crease the diameter of the stem by adding layers 
 of wood on those already formed, just beneath 
 the bark (all trees of the temperate zone, as oaks, 
 maples, and birches ; gourds, cactuses, the rose 
 family, the grape, buttercups, and many others). 
 
 Sa 
 
 
 ioboOaOOi:. 
 
 
 Cross and A'ertical Sections of Exogenous Stem. 
 In the cut. Fig. I is a segment of a cross-section of an exogen; the pith (a) occu- 
 pies the center ; then follow the wood-zone (b), and outside of this the bark (c). Fig. 2 
 is a longitudinal section of maple, less highly magnified. Fig. 3 represents a cross- 
 section of the cork-oak, showing the rings of growth, the rays which connect the pith 
 with the bark, and the cork, which is one of the bark-layers on the exterior. 
 
 In the temperate zone most exogens form every year a single layer 
 of wood, which, in cross-section, appeai-s as a i-ing ; by counting these 
 rings, the age of a tree can be approximately ascertained. 
 
 The cross-section of the palm-stem below (a) shows no concentric 
 cu'cles or distinct layers of wood, but a mass of pith through which 
 bundles of woody fiber are distributed without apparent order. In the 
 endogen, growth takes place toward the center, the newly-formed wood 
 becoming iudistinguishably blended with the other tissue (6). 
 
 Illustrations of Phanerogamous Plants. 
 The engraving represents a group of Phanerogamia. Fig. 3 is the giant-tree of 
 California, which reaches a height of over three hundred feet, and is the largest gymno. 
 spei-m known ; at c are needles or leaves of the pine. Fig. 1 is Indian corn, an endo- 
 gen ; endogens generally have parallel-veined leaves, as at a. Fig. 2 is the liver-leaf, 
 one of our earliest spring flowers — an exogen ; exogens have netted leaves, as at 0. 
 
PHYSIOLOGY OF PL AN T- LI FE. - PL A N T-ZONES. 
 
 91 
 
 PHYSIOLOGY OF riAJfT-LIFE. 
 
 Processes of Vegetable Life. — In a growing plant, the 
 following ititei'csting processes are constantly going on : Absorp- 
 tion, C'Li-culation, Metabolism, Transpiration, and Kespiration. 
 
 Absorption. — The root-hairs are constantly absorbing the 
 liipiiil in the soil. This liipiid contains inorganic salts in solution; 
 and, when brought into the plant, forms the crude sfqj. The I'oots 
 have a remarkable power of selecting those chemical elements most 
 needed by the jilant. One sijecies requires more lime, another 
 more silica, a third more magnesia ; these substances are supplied 
 by the roots as hmg as the soil affords them, and, when the available 
 supply of a needed element is exhausted, the plant does not thrive. 
 The farmer thus finds it advantageous to sow different seeds year 
 after year on a piece of ground, as repetitions of the same crop soon 
 exhaust some vital element. Absorption by means of roots is ex- 
 tremely rapid. Some plants absorb more than twice their weight 
 of material in a single season. {Si/e Johnsons '■'■How Crops Grow.") 
 
 Circulation. — Plants, as well as animals, have a system of 
 circulation. Tlie sap ascends through the woody parts of the stem 
 and Ijranclies, under great pressure, in some cases as high as thirty 
 pounds to the square inch. Rising into the leaves and other green 
 portions of the plant, watery elements are largely evaporated, and 
 the inorganic salts left behind. 
 
 Metabolism is the collective name for the chemical processes 
 which take place within the plant, transforming the inorganic 
 matters derived from the soil into cellulose, starch, sugai', and other 
 nutritious products. These processes are governed by the green 
 coloring-matter <Mo'rophyl, which occurs as grains in the cells. 
 The carbonic acid taken from the atmosphere is decomposed, and 
 the carbon unites with other elements, which become ultimately 
 new tissue ; the oxygen is rejected. It is supposed that the energy 
 exhibited in plant-growth is directly traceable to the chlorophyl, 
 which, by absorbing rays of light, transforms molecular force {re- 
 siding in the molecules, or ultimate invisible particles) into energy. 
 Heat is also an important factor in this process. 
 
 Transpiration is the exhalation of water from leaves and 
 green shoots. The amount of water transpired is greatest when 
 the air is dry and warm. 
 
 The effects of transpiration may be illustrated by placing a growing 
 plant beneath a glass jar; the under surface of the glass will rapidly be- 
 come wet with tbe condensed water from the plant. 
 
 Resi)iration. — Plants, as well as animals, breathe. During 
 the day, and most actively in bi-ight sunlight, their leaves absorb 
 carbonic acid and exhale oxygen through the minute orifices, or 
 sfomata. Tims they tend to purify the atmosphere, which is con- 
 stantly vitiated by the impurities contained in the breath of ani- 
 mals, by the products of combustion, decomposition, and volcanic 
 action. Hence the practical value of public parks and window- 
 gardens. In darlcness, however, plants absorb oxygen to a limited 
 extent. [Consult GoodaWs '■^Physiologiral Botany," p2),'231-372.) 
 
 Aqiiatic plants obtain their carbonic acid from its solution in 
 water, as fish and other gill-bearing animals extract the oxygen 
 mechanically entangled among the watery particles. Such plants 
 liberate oxygen, which attacks and destroys poisonous organic mat- 
 ter, thus freeing water from its most dangerous impurities. The 
 phenomenal spread of an aquatic weed in certain malarial sections 
 of America is believed to have saved thousands of lives. (See "A 
 Lecture on Water" hy Professor C. F. Chandler, p. 13.) 
 
 GEOGRAPHICAL DISTRIBUTIO.Y OF PLAJ^TS. 
 
 Floras — Conditions of Distribution. — The entire sj's- 
 tem of ]>lants native to any I'egion constitutes the Flora of that 
 region. The floras of different distiicts diifer widely, the character 
 of the vegetation depending on differences in the amount of heat, 
 light, and moisture received, on the character of the soil, and on 
 present or former geographical peculiarities. 
 
 The Influence of Temperature is marked in the wide 
 differences that prevail between the flora of ec^uatorial and that 
 of polar regions, between the plants that grow at the base of a 
 mountain and those which approach its summit. The effect of an 
 abundant supply of moisture is apparent in the luxurious vegetation 
 of swampy districts or of those having a high annual ramfall, as 
 compared with the meager one of arid regions in the same latitude. 
 The dift'erence is well exemplified in the abundant floras of the 
 Mississippi Valley and the Pacific coast, as contrasted with the 
 scanty vegetation of the jilains of eastern Colorado. The influence 
 of light may be inferred from the fact that many plants thrive only 
 in the shade, others only in places exposed to the sun. The nature 
 of the soil is a very important factor. Sandy soils sujjport some 
 species which will not grow at all elsewhere ; the saline soils of the 
 sea-beaches and salt-lakes sustain a peculiar type of vegetation ; and 
 some plants grow only upon rocks. 
 
 The Ai'rangement of Laud and Water in former 
 times has had a most powerful effect on the present distribution 
 of plants. As an instance, we may consider the great similarity 
 of the floras of northern Europe, northern North America, and 
 northern Asia. These regions have a large number of species in 
 common, while others are so nearly alike that they are iilainly 
 descended fi-om a common parentage. As a single familiar ex- 
 ample, the chestnut is found on all three continents, which in 
 remote times were connected. Present geogra})hy limits as well 
 the range of plants. The flora of Australia is strikingly different 
 from that of any other part of the globe, and that of Madagascar 
 appears to be almost as distinct. 
 
 Man, by bringing useful and ornamental plants under culti- 
 vation, and by unintentionally transporting seeds of weeds in the 
 prosecution of commerce, has greatly altered the natural characters 
 of floras. Thus, the cherry, originating in xVsia Elinor, the peach in 
 Persia, the lemon and orange in tropical Asia, the potato and In- 
 dian corn in South and Central America, are now found cultivated 
 in all parts of the earth where their growth is possible. Many of 
 the weeds troublesome to American farmers, as the ox-eye daisy, 
 the thistle, and the buttercup, ai"e natives of the OH World. 
 
 Plant-Zones. — In connection with the prevalent forms of 
 vegetation, the northern and southern hemispheres have been 
 divided into eight Plant-Zones, separated, not b}' parallels of lati 
 tude, but by isothermal lines. They are as follows: — 
 
 1. Tlie Equatorial Zone, between the isotherms of 78° north and south. 
 
 2. The Tropical Zone, between the isotherms of 78° and 69°. 
 
 3. The Sub-Tropical Zone, between the isotherms of 69' and 02°. 
 
 4. The Warm-Temperate Zone, between the isotherms of 62° and 53'^. 
 
 5. The Cold-Temperate Zone, between the isotherms of 53° and 42°. 
 
 6. The Sub-Arctic Zone, between the isotherms of 42° and 35°. 
 
 7. The Arctic Zone, between the isotherms of 35° and 28°. 
 
 8. The Polar Zone, from the isotherm of 28° to the pole. 
 
 (See Map tihoiHng the distribution of plants and plant-zones, pp. 94, 95.) 
 
 The Equatorial Zone includes the Eastern Archipelago, 
 the two Indian peninsulas, southern Arabia, a large part of Africa, 
 
92 
 
 THE EQUATORIAL AND TROPICAL ZONES. 
 
 embracing Soudan and Sahara, the northern part of South Amer- 
 ica, and the southern part of the West Indies and Central America. 
 
 The leav^es of many plants attain 
 
 Its vegetation is most luxuriant, 
 
 Vakieties of Palms. 
 
 In the engraving, Fig. 1 represents the date-palm, a native of northern Afriea ; the dates of commerce 
 are the fruit, and grow in bunches at the summit. Kg. 2 is a graceful Central American palm ; and Fig. 3, 
 the oocoanut-palm, now found throughout the tropical regions of the earth. 
 
 become new trunks, so that a single tree covers a great surface. 
 The baobab-tree, a native of Africa, attains the enormous circum- 
 ference of eighty to one hundred feet. 
 
 Orchids {or'Mds) abound in the damp forests of 
 the Equatorial Zone in both hemispheres. They 
 are often found resting on the trunks and branches 
 of trees to which they are loosely attached by long, 
 fleshy roots. They obtain no nutriment from the 
 plants on which they grow. Ejj'iphytes, as plants 
 which grow %tjjon other plants are called, draw all 
 their food from the atmosphere, differing in this 
 respect from parasitic plants, hke the mistletoe and 
 fungi, which live on the juices of their neighbors. 
 
 Orchids are a particularly interesting order of 
 plants by reason of their very irregular and remark- 
 ably shaped flowers, often richly colored and odorous, 
 in many cases resembling birds and insects. Then- 
 fleshy roots and stems assume most grotesque forms. 
 The flavoring extract vanilla is obtained from the fruit 
 of orchids native to Brazil, the West Indies, and Cen- 
 tral America. The nutritious substance called salep' is 
 derived from the roots of certain European and Asiatic 
 species. 
 
 While the orchids are most abundant and vigorous 
 in the Equatorial Zone, they occur also in other regions. 
 Abovit 110 species are natives of North America, and 
 many of these grow directly in the ground, though a 
 few of the more southern are air-plants. 
 
 an enormous size, while the flowers are large and brilliant. The 
 trees grow closely together and to great dimensions. Huge climb- 
 ing plants stretch from one to another, and the dense masses of vege- 
 tation are sometimes quite impassable without the use of the axe. 
 
 Palms are the most characteristic trees of the Equatorial Zone. 
 Their general habit of growth consists in the production of an up- 
 right cylindrical trunk, often a hundred feet in height, without 
 branches. This is siu'mounted by a tuft of magnificent leaves, ten 
 or fifteen feet long and three or four feet wide, their divisions ar- 
 ranged pahnately (as the fingers of one's hand), ov piniiatelij (like 
 the divisions of a feather). 
 
 Many species of palms are of the greatest use to mankind. The date- 
 palm yields an important fruit, oU is produced from several kinds ; a 
 valuable wax is obtained from a Brazilian palm, and the nuts of another 
 yield the vegetable ivory ; the tender tissue of the stems of other varieties 
 forms the sago of commerce, and wine is made from the juice of still 
 different species. 
 
 The cocoa-palm is the most valuable of all. The natives of tropical 
 regions obtain from this tree almost everything necessary to existence. 
 The nuts, which grow in clusters at the top, furnish nutritious food, the 
 mUky contents supplying also a delightful drink; a great variety of 
 utensils is made from the hard, internal shell. The sap contains much 
 sugar, and when boiled with quick-lime forms a strong cement; fer- 
 mented, it becomes wine, and, on further fermentation, vinegar; the 
 wine, when distilled, yields the intoxicating liquor known as arrack. 
 Oil is expressed from the fresh kernel, and used as a food as well as for 
 illumination. The young tufts of leaves are palatable, and form a sub- 
 stitute for cabbage. The wood is put to a great variety of uses. The 
 fibers of the leaves are woven into sails, cloth, matting, brooms, baskets, 
 and hammocks. Those of the external husk are employed in calking 
 boats, and are made into cables and cordage. 
 
 Among other important trees of this zone are the mahogany 
 of South America ; species of horribax, the silk-cotton tree of 
 Brazil and equatorial Africa ; the banyan or pagoda tree of India, 
 from whose branches aerial roots descend, enter the ground, and 
 
 Enormous chmbing plants of many different 
 kinds; the important food-plants, the banana and the plantaiu ; 
 
 the giant water-Kly of the Amazon, the Victoria regia, 
 leaves six feet across and its 
 showy flowers two feet in di- 
 ameter; and the calla-Uke 
 plants, called a'rums, which 
 bear immense leaves — also 
 characterizes this zone. Men- 
 tion should further be made 
 of the 'u^pas {poismi) tree of 
 Java, from whose sap the na- 
 tives extract a deadly sub- 
 stance to tip their arrows. 
 Animals wounded with one 
 of these poisoned shafts die 
 almost instantly ; even hand- 
 ling the foliage is attended 
 with evil consequences. 
 
 Tree-ferns are a prominent 
 feature. Their trunks are erect, 
 straight, cyUudrical columns, 
 without branches, supporting 
 tufts of leaves — which give them 
 the appearance of palms. Their 
 delicate, graceful foliage adds 
 much to the beauty of tropical 
 landscapes. 
 
 with its 
 
 ORcniD Flowers. 
 
 In the engraving, Fig. 1 represents a 
 common North American oi'chid, known as 
 the pink lady's-slipper ; Fig. 2 is an orchid- 
 flower resembling an insect; Fig. 3 suggests 
 a dove with spread wings; and Fig. 4 is 
 another bird-Uko orchid blossom. 
 
 The Tropical Zones. 
 
 — The north tropical zone in- 
 cludes a narrow belt of south- 
 ern Asia and northern Africa, 
 
 the West Indian Islands, and part of Mexico. To the south trop- 
 ical zone belong the northern half of Australia, Madagascar, Africa 
 
THE SDH-TROPICAL AND W A R M -TE M PE R A T E ZONES. 
 
 93 
 
 from the Kongo basin to the latitude of the Orange River, and in 
 South America most of Brazil, Bolivia, and Peru. 
 
 The vegetation of these countries resembles that of the equa- 
 torial zone. Palms, bananas, orchids, calla-like j>lants, and tree- 
 ferns, abound. Tlie pineapple, the tig, cotton, coffee, and sugar- 
 cane, are widely distributed. The bread-fruit tree, a plant related 
 to the fig, is native to many islands of the Pacific ; it has been in- 
 troduced into the West Indies. The papaw is also an important 
 fruit, native to the West Indies and other parts of tropical 
 America. 
 
 On the arid plains of southern Mexico, numerous species of 
 cactus {pricMy plant) are found. These plants are remarkable for 
 their peculiar forms ; some branch toward the top, others consist of 
 thick, tleshy joints. The leaves are genei'ally small, in most species 
 reduced to mere spines. In the cactuses, the green stems and 
 branches perform the ordinary functions of leaves. 
 
 Types of the Cactus Family. 
 
 In the enfrraving. Fig. 1 represents the giant cactus of Mexico and the southwest- 
 ern part of the United States ; Fig. 2, a small, very spiny species of the same region ; 
 Fig. 3, a red-flowered cactus from Brazil ; and, Fig. 4, one of thi^ common prickly pears. 
 
 One species of cactus forms a great ball, sometimes several feet iu 
 diameter, ribbed and covered with bristling' spines. Another supports 
 the cocliineal insect, from which the brilliant, crimson dye is obtained. 
 Other varieties, known as prickly pears, bear edible fruits. The night- 
 blooming cereus, famous for its large, white, fragrant flowers, is a cac- 
 tus, native to the West Indies and Central Ajnerica. 
 
 The cactuses are not all confined to the warmer parts of the globe : 
 a few of the prickly pears extend into the warm-temperate zones, and 
 one species is found in the northeastern part of the United States. 
 
 The Sub-tropical Zones (including the southern extremi- 
 ties of Europe, the opposite shores of Africa, and the Gulf region 
 of the United States), with their hot summers and short mild win- 
 
 ters, form the transition between the tropical and temperate re- 
 gions; their tlora combines the characteri.stics of both. Much of 
 the vegetation is green throughout the year. The laurel and myr- 
 tle, magnolia and fig, occupy a pronduent place in the fiora. 
 
 The remarkable drafjoiCii-hlood trees of the Canary Islands and the 
 west coast of Africa, whence is obtained the resinous coloring-matter 
 used for tingeiug varnishes and staining marbles and iilasters, ai'e natives 
 (_)f the north sub-tropical zone. The celebrated ti'ce of Teuei'itfe is stated 
 to have been seventy feet high and forty-eight feet in circumference, 
 and was worshiped by the aboriginal inhabitants. It was completely 
 destroyed in 1867. 
 
 The evergreen cork-oak of soutljern Em-ope and northern Africa is 
 also a characteristic tree of the north sub-tropical zone. The cork of 
 commerce is the outer layer of the bark. The tree, which attains a 
 height of about thirty feet, is not subjected to the operation of barking 
 till it has reached the age of fifteen or twenty years ; after which it is 
 regularly stripped every eight or ten years, each time yielding a finer 
 quality of cork. It continues to be productive, and to thrive under this 
 treatment, for more than a century. 
 
 Roses are largely grown in this zone (especially iu Tm-key and Per- 
 sia) for the purpose of manufacturing attar and rose-water. The flowers 
 are gathered at sunrise and distilled the same day; but they contain the 
 fragrant oil in such minute quantities that it requires more than a thou- 
 sand roses to yield two grains of the costly attar. From the petals are 
 made conserve aud infusion of roses, agreeable medicinal jireparations. 
 
 The bamboo, a tree-like grass growing to a height of fifty oi- 
 si.xty feet, has been called " one of Nature's most valuable gifts to 
 uncivilized man." Its slender stem, from five to fifteen inches in 
 thickness, is divided into joints, and develops so rapidly that it 
 attains its full height in a few months ; a growth of two and a half 
 feet has been observed in a single day. A decoction of the leaves 
 of the bamboo furnislies a valuable medicine ; its seeds are a favor- 
 ite food ; and its tender shoots are eaten like asparagus, or made 
 into pickles and confections. A great variety of utensils is manu- 
 factured from its stem, and jiaper is made from its pulp. Its joints 
 serve as water-buckets and cooking-vessels ; small ones, as bottles. 
 Dwellings are constructed entirely out of this plant ; and vessels 
 are rigged from its various parts. 
 
 Bamboos are extensively imported for a variety of purposes, 
 especially for basket- and wicker-work ; carefully selected strips of 
 a certain species are united to make the " hexagonal split-bamboo " 
 rod of the modern angler. (On the bamboo and its economic 
 importance, consnlt '■^The Treasiiry of Botany.''^) 
 
 The Warm-Temperate Zones. — In these zones many 
 plants are still e\ergreen. A few jjalms are found, such as the pal- 
 metto of the southern United States, a small species in southern 
 Europe, and others in Chile. The north warm-temperate zone is 
 chai'acterized by forests of deciduous trees (whose leaves faJl in 
 autumn), such as oaks, elms, etc., and by the tig, orange, pomegran- 
 ate, peach, olive, and grape ; in the south warm-temperate zone 
 grow many large grasses, like the pampas-grass of the Argentine 
 Republic. 
 
 The mammoth trees of California (Sequoia), the nudberry whose 
 leaves supply the silk-worm with food, the camphor-tree, and the camel- 
 lias of eastern Asia, are important elements of the flora. 
 
 The tea-plant is allied to the camellias. There are nvimerous varie- 
 ties produced by cultivation, but all are now generally regarded as be- 
 longing to one species. They are both wild and cultivated in China and 
 Japan ; the area devoted to the cultivation of tea in China is 25,000,000 
 a<'res. The beverage was first introduced into England about KilO. Nu- 
 merous substitutes have been tried for tea, but none have met with much 
 favor. Attempts to cultivate it with profit in the United States have 
 hitherto proved unsuccessful. {See Moneifs "Tea-Cultivation.'') 
 
66 
 
 P 
 
 Z 
 
 A R 
 
 z? 
 
 T 
 
 C 
 
 O 
 
 r 
 
 7 
 
 C 
 
 uV 
 
 liOnpitude 
 
 , Voi-lfc 
 
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 DEVON 
 
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 69 
 
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 XONE 
 
 COLllj-TEWlP^^ 
 WARl^-TEWPtRATC Z fj £ 
 
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 SUB-TljjOPlCAlpZONE 
 
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 (NORTHJ 
 
 et»^ 
 
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 v^. 
 
 
 
 
 VANCOUVER I 
 
 
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 7 Buslies/ 
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 A 
 
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 TABOS 1-5. .-; 
 
 ^f 
 
 V<1 
 
 l¥-9 
 
 rsi. 
 
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 FORESTS OF 
 
 
 i.^ ^Spruce, Larc"h, etCi 
 ""^fTp Beny-'buHliea 
 
 "otntJifS 
 
 X 
 
 Gr!is3-:- 
 
 BRITISH-.'^^-J 
 ISLES lt„l, 
 
 e se; etc. 
 
 uC--^' 
 
 I.-' 
 
 rjji-. 
 
 xiiy 
 
 Gi;a. 
 ■, CacUis 
 
 ^ 
 
 Z N t '^ »- . 
 
 SANDWICH IS. 
 Suf^ar-caie, Rict 
 Taro or ICs Lo, Aca 
 Custard-applt J Cilru; 
 
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 E Q iJ A T 
 
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 .bE«t 
 
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 At 
 
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 PHOENIX IS. 
 
 Bre|aa-£ 
 
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 til b o o, tf .^ 
 
 runs. 
 
 SOCIETY 18. 
 
 t: ut 
 
 P al ni. 
 
 - a 11 '^' • MARQUESAS IS. 
 
 „ Pine-":. 
 
 •. PAUMOTU 15. 
 
 ILLUSTRATING THE DISTRIBUTION OF 
 
 PLANT LIFE ON THE EARTH. 
 
 103 73 
 
 BERMUDA IS. 
 *. Arrcrvv'-root 
 Teg eta"ble3 
 
 oj 
 
 Tange 
 
 \ ^-^ BAHAMA IB, 
 ' Pjpc-apple 
 
 ^ 
 
 
 WEST 
 
 aogany- 
 
 CENTRA]? 
 AilERICi'A 
 
 SnniDs 
 
 Pricklj'-gear 
 
 GALAPAGOS 15. '^ 
 
 TRQP^ 
 
 5V)t 
 
 W^ 
 
 Cf^^ 
 
 SUB-TRO^ 
 10^ 
 
 Questions on the Map of Plant Zones Locate the eight plant 
 
 zones on the map, and notice the isotherms by which they are bounded. Which of 
 the plant zones has the most luxuriant vegetation ? In what plant zone do you live ? 
 Why do the boundaries of the more northerly zones run so far north in the Eastern 
 Continent? What are the climatic limits of the growth of maize? The ranges of 
 the tree-fern and the fig ? Point out the native country of the potato, yam, maize, 
 millet, coffee, caoutchouc. Name any marine plants you may find noticed on the 
 map. Enumerate the forest-trees that accompany pines in the temperate latitudes 
 of the United States. What corresponding trees are found south of the Equator ? 
 
 Mention the food-plants of tlie coldest portions of the globe ; of the warmest. 
 What plants are most widely distributed ? How far does a knowledge of geology 
 help to explain an apparently wide range in the distribution of certain plants ? How 
 far do islands exhibit the vegetation of adjacent continents ? Point out the striking 
 botanical features of the Amazon Valley; of the west coast of Africa; of the Medi- 
 terranean shores ; of Mexico ; of Siberia ; of the Sandwich Islands. What are the 
 peculiarities of Australian vegetation ? Compare the vegetation of the Pacific coast 
 of North America with that of the Atlantic shore. Enumerate the characteristic 
 fruits of southern Asia ; of tropical Africa ; of southern California ; of the islands 
 of the Pacific Ocean. 
 
 What is the range of tobacco? of the banana? of indigo? of sugar-cane? 
 Where is amber found ? peat ? bog-moss ? myrrh ? copal ? the aloe ? the mango ? 
 vanilla ? sarsaparilla ? In what part of the globe are the spices of commerce largely 
 cultivated ? Where does the castor-oil plant grow ? 
 
 .Sea 
 
 ■u±« p>ffee Su^-Cane 
 ]| jMirsaparilfa 
 
 "\vi//almW' Sjuv-iajjp- 
 
 Indigo 
 
 ■^ 
 
 w-wfl 
 
 Sargas 
 
 «o Sea Algir 
 
 TROPIC OF-.CANCER 
 
 ^ 
 
 ' ' Cotton 
 
 Sugar 
 Coffee 
 
 Orange- ,—- — 
 
 Wheat 
 
 Vine, Orange, 
 Fie, -"Wheat . 
 
 A 
 
 CAPE VERD is:* 
 
 ut 
 
 .V 
 
 Timber 
 
 .tain 
 jffee 
 
 ""-^otton 
 5^?"» ^jManioc 
 Pepper I Y 
 Pine-aiixiley^ 
 
 ^- 
 
 Sagar-e^ 
 Maniof r 
 lotton Cocoa-nut \ 
 .-Doa Piii^ . 
 aliogany /Collon, 
 XoKwooi' 
 Sut 
 Sweel-p 
 
 PWT 
 
 Wa-xfi 
 
 rfitain 
 
 ^. 
 
 10 
 
 X' 
 
 old- 
 
 TlENlP 
 
 :^ 
 
 20NE- 
 
 ^jB. ARCTIC 
 
 TONE 
 West E-iiit 
 
 Longitude i r 
 
 > 
 
 ASCENSION 1, - 
 
 ^v^ 
 
 -TROPIC OF CAPRICOR.j 
 
 ^ 
 
 mSTAN D'ACUNl 
 
 o 
 
 FALKLAN, 
 ^ Bushes 
 T lasac-i;! 
 
 .<^V 
 
 Sff 
 
 -2fe 
 
 
 '^^"i. 
 
 /vinii-''Nlpluni,'Oali. BeecK- 
 
 ■ ee^.W^I-Waguo)}?. 
 
 HetnV' ' Chestnut. . -Tobft«)i" 
 
 ii..„Yi!i*.My;' — 
 
 Sox] 
 
 ^^'o. 
 '"•^"'c 
 
 COLD- 
 
 TEMPER- 
 
 WARM-TEMP, 
 
 \ Europe 
 
 
 w 
 
 
 V 
 
 VEETICAL PLANT ZONES 
 
 IN THE NORTHERN HEMISPHERE, 
 
 From their Latitude at Sea-level to their Altitude at the I 
 
 -The Vertical scale is in projiortion to the scale ofLatit 
 
v: 
 
 ^i" 
 
 a^ 
 
 -Lou^iludc 
 
 C 
 
 R ^lyS, <1 . 
 
 I&'tC Wheaf r^ / If 
 
 \ , Barley y»; Rj|^ IVh.^! V 
 
 4- -( u,^-.$^-yrf^-7-^" 
 
 Pe.irh / il..,„it 
 
 orii» 
 
 R W4L'"''\j^\ omuSrrm.; 
 
 C... ***•.,*.*.' Mulberry. 
 
 Barley 
 
 ^••"PAP.... 
 
 ., . i)cr,,rl of G»>'' eP«; 
 
 grove S-iri^hum 
 
 Mangoi Q^^ 
 Pl;*nlainl Copal 
 
 " • Planlain 
 
 ur. iiiiy''f\ Caoutchouc 
 ffove y^C F Baobal) 
 
 ) Hfe-*^ 
 
 MeArTlnrits 
 « ^Sea-weed 
 
 ^^UTl A^ 
 
 ^q.TEM perate z 
 
 0^^ 
 
 ">/^^ ^ /I '^ ^jj Ty Cprpanlhrinum 
 t^^^t^^Cls" Bignniaa 
 -■^Cction y Vafijj'lior-tree 
 
 "obacco ;:* Swecl-potaC 
 
 ilelona 
 ,-MttIet— -^ • TROPIC OfIcaNCER 
 
 — — ^-<<> \ 
 
 WARM-TEM PERATE ZONE 
 SUB.TR^0P/!c4^ 
 
 ^•^^^^^^I^.ijnlt of 
 
 ZOH E 
 
 BeU-l-nut-:' 
 Rice - 
 Sweel-potaio 
 
 Cocoa-nut Palm Qnnamoa 
 
 „ , 'v, CftSSlft 
 
 Esculent Koots 
 EQUATOft 
 
 Cocoa-nut Falin 
 
 N D I 
 
 • •wAURtTIUS I. 
 Fanjanus or & rew-jloft 
 
 Cocoa-out Palm 
 
 n s i V e 
 
 shiiigton 
 
 "os 
 
 "f Sea- weed. 
 
 -■■^of 
 
 "Lim* 
 
 E 
 
 , S *^ L— ) _AIaize \ 
 
 Till- 41 ,,„„„, s^™=t 
 
 Sl(l!lt^»» ISLANDS 
 y J ^'utinec. CuTnani< 
 
 ^"^r^wp a;"^^ jkS,\ jrniM!«t ■ 
 
 MAR!ANA 
 
 on 
 TobaciM^LAORONE I&. 
 
 Tropical 
 
 62 
 
 59 
 
 rrr _-• MARSHALL 
 
 <^ Zone 
 
 (NORTH) 
 
 • ■"' P^nOanui 
 
 % E Q U A 
 
 EaUA70fl--^-C- 
 
 
 ''c. 
 
 T.O R I A L 
 
 PHOENlilts. 
 
 ''vr 
 
 
 
 Ar 
 
 ■"paT"'' 
 
 -V 
 
 SAMOA oJ'am 
 
 HEBRipr«'./jL 
 
 ?d 
 
 •* v., « 
 
 +«- 
 
 T~SO 
 
 1(7 Enst 180 -West 
 
 TROPIC OF CAPHIC(WnP / d A L 20H'E"'- ■ 
 
 ■ sub^TropicIl^.o.e 
 
 flyrtle 
 
 Bi; 
 
 jTimber Trees "**.^ O3I 
 /Ai aucaria-jiine "^^ 
 
 ^■- ■ R,,,j — 
 
 HTieat 
 
 Honejsui 
 
 O WARM- 
 
 ^' 1 LMHtHA I t 
 
 a^s- 
 
 COLD- 
 TEMP. ZONE 
 
 53 
 
 
 
 
 
 \!r 
 
 
 '%. 
 
 ,!>*"■ 
 
 ibcr Bcmp I * 
 
 -EQUATOR 
 
 MAP TO ILLUSTRATE PLANTS 
 
 n.WI.Nt; IMPORTANT 
 
 COMMERCIAL PRODUCTS. 
 
 
 Rhubarb „. 
 
 arky 
 
 0»t9- 
 
 JlUUU*k 
 
 SOTBhai 
 
 " Sweet-potato 
 
 ^ Cotton >' S« 
 
 i Jul* 
 FoppjS" 
 
 I PaiDtnor f 
 
 ""^y 
 
96 
 
 AKCTIO VEGETATION. — PLANT-PRODUOTS. 
 
 The Cold-Temperate Zone, in the northern hemisphere, 
 includes the State of Washing-ton and British Cohimbia on the Pa- 
 cific, the northern parts of the United States, central Europe, and 
 the more southerly regions of central Asia. In the southern hemi- 
 sphere, Patagonia, the southern portion of New Zealand, and pai-t 
 of Tasmania, are the principal land-areas that belong to this zone. 
 
 Its flora is characterized by forests composed of conifers — as 
 pines, firs, hemlocks, cedars, larches, the gigantic redwood of the 
 Pacific coast of JSTorth America — with many deciduous trees. The 
 conifers are the most marked feature. Most of our wheat is pro- 
 duced in this zone, the plant finding here favorable conditions for 
 its growth. 
 
 The Siib-arctic Zone, represented in the southern hemi- 
 sphere only by a few barren islands, includes in the northern the 
 Pacific shores of Alaska, portions of Canada and the northern 
 United States, Newfoimdland, Iceland, most of Norway and Swe- 
 den, and a belt of land extending from central Kussia to the Jajjan 
 Sea. The low mean anmial temperature of these regions would 
 restrict vegetation still more than it does, were it not for the long 
 summer days. In certain sections, the grains mature and even 
 thrive. The birch, willow, fir, and hardier pines, are the represent- 
 ative trees. The swamps are generally filled with peat. Eatable 
 
 kinds of sea-weed are 
 collected on the coasts. 
 
 The Arctic Zone 
 
 includes a narrow belt 
 north of the sub-arctic. 
 Vegetation generally is 
 dwarfed and stunted. 
 Wide regions on the 
 northern boundary of 
 this zone are covered 
 with lichens, which 
 furnish the reindeer its 
 food. A few grasses 
 are found. Bog-mosses 
 are aljundant. 
 
 The so-called "rein- 
 deer-moss " is really a li- 
 chen. It grows directly 
 on the ground, and in 
 immense quantities. As 
 the reindeer is an all- 
 important animal to the 
 Laplanders and other 
 high northern races, this 
 little plant may be re- 
 garded as indirectly the 
 source of their support. 
 
 The Polar Zones 
 
 comprise, in the north, 
 the northern extremi- 
 ties of Europe, Asia, 
 and America ; and in 
 the south, the Antarc- 
 tic Continent. 
 
 Characteristic Arctic Plants. 
 
 Fig. 1 is an Arctic lichen ; Fig. 2, a species of 
 ivintergreen from the Antarctic zone ; Fig. 3, an Arc- 
 tic willow ; and Fig. 4, one of the Arctic grasses. 
 
 The vegetation is mainly composed of lichens, and of bog-mosses, 
 which form the tundras. There are no trees, and the only woody plants 
 are the dwarf polar willows, attaining a height of but a few inches ; one 
 might crush a forest with his foot. Rushes, several species of the but- 
 tercup family, and a few grasses are found in some places. 
 
 The climate of Spitzbergen, being tempered by the GuK Stream, 
 allows there a more abundant flora. (On Arotic vegetation, consult 
 Nares\s '^Narrative of a Voyage to the Polar Sea" 2^- HO.) 
 
 Plant-Life at Different Heights. — As elevation above 
 sea-level modifies heat, so it affects vegetation. If we ascended a 
 tropical mountain to a height of 15,000 feet, we should have a 
 succession of climates and plant-belts similar to those met with in 
 going from the Equator to the Arctic regions. 
 
 Questions. — What is meant by the flora of a comitry ? How do plants difl^er 
 from animals ? From inorganic matter ? How many species of plants 
 are supposed to exist ? Name, define, and illustrate the five sub-king- 
 doms into which they have been divided. What are floral organs ? Ex- 
 plain the functions of the root, the leaves, the flower; the difference be- 
 tween endogens and esogens ; between evergreen and deciduous trees. 
 
 Name and explain the several processes of vegetable life. How is vegetation 
 influenced by climate ? Mention the eight plant-zones, and the charac- 
 teristic species of each. Show that the distribution of plants varies with 
 difference of level as with difference of latitude. 
 
 PLAKT-PROBVCTS. 
 
 Man obtains from the Vegetable liingdom many 
 products necessary to his welfare ; indeed, he can exist on these 
 alone. 
 
 The plants most important to man may be included in the fol- 
 lowing groups : 1. Food-plants. 2. Plants yieldiiig fibers. 3. Tim 
 ber-trees. 4. Plants yielding sugar. 5. Medicinal plants. 6. Plants 
 yielding beverages. Y. Dye-plants. 8. Spice-jjlants. 9. Plants 
 yielding oils, gums, and resins. 10. Plants pelding narcotics. 
 
 Food-Plants comprise cereals, tuberous and bulbous plants, 
 plants bearing edible fruits, and jjlants yielding succulent stems or 
 leaves. 
 
 Cereals are the grain-producing grasses ; the most important 
 being wheat, rice, Indian corn or maize, oats, barley, and rye. 
 
 Wheat.— Of the cereals, wheat is the best adapted for the food of 
 man, as it contains all the elements necessary to support life. At the 
 present day, wheat is grown most extensively in the temperate zones. It 
 has been cultivated from remote antiquity ; but its native region is not 
 definitely known. It will not grow in hot countries at sea-level, but 
 thrives at elevations of from 8,000 to 10,000 feet. 
 
 Rice is second only to wheat as an important food- product. It is the 
 chief support of the inhabitants of western and southern Asia, whei-e 
 it is probably indigenous, and is largely used in all warm countries. It 
 has been cultivated from prehistoric times. 
 
 Millet (from the Latin mille, a thousand, in allusion to its fertility) 
 comprises a number of important cereals, long cultivated ui the eastern 
 hemisphere. The grain is extremely nutritious. It is estimated that 
 one-tbu'd of the inhabitants of the globe subsist on the millets. 
 
 Indian corn is a native of Central or South America, but exactly 
 where it originated is as yet unknown. It was cultivated by all the 
 American tribes, and at the time of Columbus was a staple article of 
 food over the greater part of both the American Continents. It was soon 
 exported to Europe. 
 
 Oats are considered by De Candolle as native to eastern temperate 
 Europe. They are mainly cultivated in northern and western Em-ope, 
 and the northern United States. V/ith us, their principal use is as food 
 for stock. 
 
 Barley has been under cultivation since early ages. It has never 
 yet been certainly found in a wild state, and its native home is but a 
 matter of conjecture. Barley matures in colder climates than the other 
 cereals, and is the most important food-plant of Siberia and northern 
 Europe. Rye, also, is most prolific in northern regions. It probably 
 originated iu eastern Europe, but is not now known in a wild state. 
 
PLANTS YIELDING TUBERS, FRUITS, KDIHLE STEMS, AND FIBERS. 
 
 97 
 
 Buckwheat, though not a true cereal, should be noted in this connec- 
 tion. It has been found wild in Mantcliooria, and its origin is undoubt- 
 edly Asiatic. It is extensively cultivated throughout the north temperate 
 zones. {Compare De CandoUe's "Origin of Ciiltiratvd Pkuils:') 
 
 TuInTous and IJulboiis Plants. — The mo.st iniixirtant 
 plants of this cliiss are tiie potato, y:ini, and inanioc. 
 
 The ]Hitato, a native of Cliilc, and ])erliaps of other portions of 
 tlie Andes, is now cultivated in all parts of the civilized world. 
 The tuliers ai'c thickened portions of subterrauean branches of the 
 plant, and not roots. 
 
 The sweet-potato probably originated ui tropical America, antl is of 
 wide-spread cultivation. It bears true thickened roots. 
 
 Several species of yams are raised in the warmer regions of the 
 gl<>l)e. Their roots grow to great dimensions, sometimes weighing forty 
 pounds or more. 
 
 The manioc is a shrul) with large roots, native to tropical America, 
 and cultivated there, in Africa, and in parts of Asia. The roots contain 
 a i)oisonous juice, ^vllich is separati^d by griiuling, w;usliiiig, and baking. 
 The residue is called cas'/iura, or wlicn further purified tapioca, and is 
 a most important food-prcjduct. 
 
 Onions are true bulbs. The plant belongs to the lily family, aiul is 
 stated by De Candolle to be wild in central or eastern Asia ; it was cul- 
 tivated by the ancients. 
 
 Plant.s bearinj": Edible Fruits. — Among herbaceous 
 l)Iants of this class, the beans are the most important ; through cul- 
 tivation, they have developed into a great many varieties. Peas, 
 also, are liere to be noted; and the numerous kinds of berries, in- 
 cluding the grape. There are also many trees bearing edible fruits. 
 
 The Ban.\na and the Pine-Apple. 
 
 The apple is a native of Evu'ope : the pear, of Europe and Persia ; the 
 plum, of Europe and western Asia; cherries, peaches, and apricots, are of 
 Asiatic origin. Bananas are generally considered indigenous to south- 
 ern Asia ; they are more properly perennial herbs than trees, as their 
 stems do not become very woody. 
 
 The mangosteen is a most delicious fruit, al^out the size of an apple, 
 reddish-browai in color, with a thick, nutritious rind. It grows wild in 
 the Sunda Islands and the Malay Peninsula, and is cultivated in Ceylon. 
 
 The mango is an important East Indian fruit. It has been mtro- 
 ducod into troiiical Africa and America. 
 
 The fig is regarded as a native of the Mediterranean region. The 
 tree is allied to the mulberry, but the form of fruit is very peculiar, be- 
 ing a heshy, hollow .sac. It is extensively cultivated in all tropical 
 countries. The dried figs of connnerce come mainly from Turkey and 
 tln! islands of the Mediteri'aiuian. 
 
 The piiu'apple is an imjiortant and familiar fr nil, native to tropical 
 America, and cultivated with some success in Florida. 
 
 The bread-fruit tree grows from thirty to forty feet in height, and 
 has large, deeply-parted leaves. The so-called fruit, a foot or more in 
 length, is of a spongy consistence, white, and nutritious. The true fruits 
 are nuts, imbedded in this mass; l>ut they are rarely pioduced by culti- 
 vated plants. The bark of the bread-fruit tree is composed of very 
 strong fibers, from which a fine chjth is woven. 
 
 Plants bearing- 
 
 or Leaves. 
 
 garden vegetables- 
 
 -cab- 
 
 Siicculent Steins 
 
 Among these are several of our common 
 bage, lettuce, celery, and spinach. 
 
 The cabbage is probably of European origin. It is found in a wild 
 state on the coasts of Denmark and the British Isles, and on the northern 
 shore of the Mediterranean Sea. Ninnerous vai'icties have been pro- 
 duced by ejiltivation, among them cauliflower and broc'coli. The many 
 cidtivated forms of lettuce are generally regarded by botanists as origi- 
 nating from the wild prickly lettuce, which grows in southern Europe, 
 northern Afiica, and western Asia. Celery is common as a wild plant 
 from northern Eurojie to India. 
 
 Plants yielding Fibers furnish matei-iais for thi-ead, cloth- 
 ing, ropes, etc. The most important are the cotton-plant, hemp, 
 flax, and jute. 
 
 Cotton is the long hairs attached to the seeds of the cotton- 
 plant. These seeds are borne in a pod, which bursts when ripe, 
 allowing them to be wafted through tlie air like thistle-down. The 
 object of these hairs is to facilitate the natural distribution of the 
 seed; but man has taken advantage of their structure, and from 
 cotton many fabrics are woven, notably muslin and calico. 
 
 Botanists at present regard the cotton-plant as of three sijecies — the 
 Tree-Cotton, a native of troi^ical Africa ; the Barba'dos Cotton, of a 
 great nmiiber of varieties, most probably native to tropical America, and 
 uicluchng the valuable Sea-Island Cotton, growing on islands along the 
 coasts of South Carolina and Georgia ; and the ordinary Herbaceous Cot- 
 ton, of very ancient Asiatic cultivation, the commonest in Europe and 
 the United States. 
 
 Hemp, a native of western Asia, where it is yet found wild, is exten- 
 sively cultivated in the north temperate zone. A very strong fiber is 
 obtained from it, and woven into cordage, ropes, etc. The greater part 
 of the supply comes from Russia. In. the mountainous districts of 
 India, the plant is ch-ied and smoked, or macerated in water, to form an 
 intoxicating ch-ink. 
 
 Flax is an important textile fiber obtained from the bark of an 
 herbaceous plant, doubtless indigenous to the Old World, and m one 
 form still foimd wild in northern Africa and western Asia. The woven 
 fiber is called linen. The seeds form an article of commerce ; and from 
 them Unseed-oil is expressed, of which large quantities are used in the 
 manufacture of prmters' ink. The residue from dressing the fiber is 
 called tow. 
 
 Jute is a fiber obtained from the stems of a plant extensivelj' culti- 
 vated in southern Asia. It is woven into mats, canvas, and other 
 articles. Jute has been introduced into tropical Africa and America. 
 
 Timber-Trees. — Pines and other conifers are the most im- 
 jiortant timber-producers. There are about seventy species of pine 
 known, thirty-five of which are natives of the United States. Of 
 these, the most important are the white-pine, which forms the 
 forests of the northern and northeastern parts of our country ; the 
 long-leaved pine and Georgia pine of the southerti Atlantic States ; 
 and the western yellow -pine of the Eocky Mountain region. 
 Among other coniferous trees are the spruces, lirs, white and red 
 cedars — the fomier extensively used for shingles and the latter for 
 
98 
 
 FORESTRY. — MEDICINAL PLANTS. — TEAS AND COFFEES. 
 
 lead-pencil wood — the southern bald cypress and the redwood of 
 the Pacific coast. The Scotch fir is the most important timber-tree 
 of western Europe. 
 
 Of oaks, there are a gi-eat many species. The live-oak of the South- 
 ern States, and the white-oak, are the most valuable ; in Europe, the 
 Enghsh oak and the Turkey oak. The locust yields a very hard and 
 durable wood ; the chestnut is much used for railroad-ties. The maple, 
 ash, and tulip tree, are extensivelj' employed for indoor work. 
 
 Among familiar tropical woods are the rose-wood and mahogany. 
 Brazil is wonderfully rich in beautiful wood products. 
 
 Forestry. — The care and cultivation of forests are subjects to 
 which marked attention is paid in Europe, and which are beginning 
 to assume great importance in America. The error involved in 
 the indiscriminate cutting of trees is now apparent, through agita- 
 tion and discussion by societies and newspapers. From all parts 
 of our country where the forests have been cleared, comes the 
 comj^laint of diminished water-supply. Rains are less frequent 
 and heavy, springs and streams dry iip ; snow does not fall in 
 sufiicient quantities to protect the ground in winter, and all the 
 evils of excessive drought are experienced in summer. {See Dr. 
 J^i'own's '■'■Forests and Moisture^'' p. 165.) 
 
 Forest-cover determines the water-supply of a region, which is 
 invariably diminished or irregularly dispensed in countries that 
 have been subjected to reckless denudation. By storing up the 
 rainfall in the spongy soil about their roots, and mechanically 
 keeping it back while protecting it by their leaves from evapora- 
 tion, forest-trees tend to distribute it gradually and uniformly in 
 the natural river-channels. In a denuded region, it runs rapidly 
 into the valleys, and swells the streams to dangerous proportions. 
 
 In mountainous countries, forests act as barriers against ava- 
 lanches ; while their roots, extending deep into the soil, prevent its 
 being easily loosened by melting snows. Many villages in Switzer- 
 land and northern Italy would be uninhabitable were it not for the 
 wooded tracts above them. Forests also serve to retard the prog- 
 ress of storms and modify the violence of winds ; thus they give 
 important protection to cultivated districts, and tend to prevent 
 sudden and extreme changes of weather. Their leaves, falling 
 periodically, decay and em-ich the neighboring land. {Consult 
 Professor UougKs ^^ Elements of Forest/ry.") 
 
 The encouragement of tree-planting has been begun in many states 
 by the a])pointment of an "Arbor-Day." There are great portions of our 
 country suitable only for forest cultivation, and the possible financial 
 returns from tree-planting have been very generally overlooked. There 
 is a growing demand that the Government shall obtain control of our 
 standing timber by setting apart forest reservations,, and shall adopt 
 measures for planting extensively, not only in deforested regions, but 
 in the treeless states and territories of the West. 
 
 Plants yielding Sugar. — This valuable product is obtained 
 principally from the sugai'-cane, the beet, sorghum, the sugar- 
 maple, and from several palms. 
 
 Sugar-cane is a tall grass, somewhat resembling Indian corn, native 
 to southern Asia, and grown in all warm regions of the globe. The 
 ordinary process of extracting the sugar is to crush and press the stalks, 
 and then boil the juice until the crystalline product is formed. Another 
 method of recent introduction and liable to replace the above, is to chop 
 the stalks into small pieces and extract the sugar by immersion in water 
 — a process known as " diffusion " ; the liquid is then concentrated, and 
 the sugar remains. The uncrystallized residue in these processes is 
 called molasses, or su-up. 
 
 Sorghum is another large grass, long cultivated in China, and now 
 grown in the southern United States. It does not require so warm 
 a climate as the sugar-cane, thi-iving as far north as Cape May, New 
 .lersey. 
 
 Medicinal Plants. — A large number of plants yield prod- 
 ucts used in medicine. Some of the most important of these are 
 quinine and its associated alkaloids, aconite, nux-vomica, and cocaine. 
 
 Quinine, cinchonine, cinchonidine, and other alkaloids acting as feb- 
 rifuges, are obtained from the bark of trees called Cinchona, natives of 
 the Andes of South America. Cinchona-trees are now also cultivated in 
 India and the West Indies, and the price of these invaluable remedies, 
 formerly so high, has been very much cheapened in consequence. 
 
 Cocaine is an anaesthetic of recent introduction. It is obtained from 
 the leaves of the cuca or coca, a shrub which grows on the slopes of the 
 Bolivian and Peruvian Andes. Its leaves were chewed by the Indians 
 in the most ancient times, to remove drowsiness, enliven tlie spirits, and 
 impart nervous energy to endure cold, wet, great bodily exertion, and 
 even want of food. It is estimated that coca is still used as a nervous 
 stimulant by 8,000,000 of the human race. 
 
 Plants yielding Beverages. — Wine is produced in great 
 quantities by the fermentation of the juice of the grape. Numer- 
 ous sj^ecies of grapes grow wild on both continents, and from them 
 the many varieties of cultivated grapes have been derived. Wine 
 is also made from a number of other fruits. Rice-wine forms the 
 principal and almost only alcoholic beverage of Japan. 
 
 Infusions called "teas" are made from the leaves of a number 
 of plants, notably the Chinese tea {ts\i) shrub. Green and black 
 teas are not from different species of plants, but are differently 
 prepared. To produce the former, the leaves, as soon as plucked, 
 are placed in iron pans and exposed to the action of heat for a few 
 minutes only ; then they are rubbed together, and a second time 
 " fired " for two or three hours, being constantly stirred by persons 
 in attendance, and in the case of fine tea " fanned," to preserve 
 their green color. Small quantities of Frussian-blae are added to 
 intensify the hue. In the case of black tea, the leaves are exposed 
 to the air for some time before they are fired. Chinese ladies 
 anoint their heads with tea-oil, extracted from the seeds. 
 
 Mate-plant, Coffee, Tea-plant in Fkhit. 
 
 Paraguay tea or mate (niah'tay) is prepared from the dried leaves of 
 an evergreen-tree of the holly family. It has been in use among the 
 Indians from time immemorial, and is now consumed by almost the 
 whole population of South America. 
 
 Labrador tea is the di-ied leaf of a marsh Le'dum peculiar to the 
 colder regions of North America. It possesses narcotic, soothing, and 
 exhilarating properties. 
 
 Coffees are infusions of seeds. The low, branching coffee-tree is a 
 native of Abyssinia, and is widely cultivated in all warm countries. Its 
 fruit is red, and about the size and shape of a cherry, containing two 
 seeds, with their flat sides contiguous. These seeds are the "coffee- 
 beans." (See HewitVs '^Coffee; its History, Cultivation, and ?7ses.") 
 
 The cacao-tree, indigenous to tropical America, is cultivated in most 
 warm countries. The fruit is pod-like and contains a great many seeds, 
 called chocolate-beans, from which chocolate is prepared. 
 
SPICES. — GUMS. — NARCOTICS. 
 
 99 
 
 Dye-Plants.— Indigo is n])taiiied in greatest quantities from 
 two plants of tlio bean family, one a native of India, the other of 
 the West Indies. The blue coloring-matter is obtained by macerat- 
 ing the green plants in water and collecting the sediment. Log- 
 wood, a Central American tree, yields a deep-red dye. Madder is 
 au important red dye, obtained from the roots of a European plant 
 of that name. It is now nearly superseded by the introduction of 
 anih'ne colors. 
 
 Spice-Plauts include the nutmeg, the pimento-tree (yield- 
 ing allspice), the cinnamon, cloves, and the peppers. 
 
 Nutmegs are the seeds of a small tree of the laurel family found in 
 the Malay Archipelago. These seeds are enveloped by a net-like cover- 
 ing, the mace of commerce. 
 
 Cinnamon is tlie inner bark of another tree of the lam-el family. It 
 is botli wild and cultivated in southern India and the Malay Archipel- 
 ago. Tlie bark of a related species furni.shes cassia, which is umch used 
 to adulterate cinnamon. 
 
 Cloves are the dried flower-buds of a tree which formerly grew 
 chiefly on the island of Amboyna, one of the Moluccas, but is now cul- 
 tivated in India, Zanzibar, and elsewhere. 
 
 Pepper is the fruit of a cliinbing plant from India. Its berries 
 resemble currants, and when dried and powdered constitute black 
 jiepper ; when the skin is first removed by washing, they form white 
 pepper. 
 
 Retl or Cayenne pepper (capsicum) is obtained from the fruits of two 
 South American plants, now generally cultivated in tropical and warm 
 countries. These belong to the potato family. 
 
 Plants yielding Oils, Gums, and Resins. — Of these 
 there are a great number. Linseed-oil is obtained from the seeds 
 of tiax ; castor-oil from the seeds of the castor-oil plant, also known 
 as Palma Christi. Oil is obtained from the seeds of many other 
 plants, as cotton and rape. Cotton-seed oil is largely used as a 
 food and in the arts. 
 
 Gums are soluble Li water. Gum-arabic, the most important, 
 is obtained from several acacias in Asia and Africa. Gum-traga- 
 canth is yielded by a pea-like shrub of the mountainous regions of 
 western Asia. 
 
 Eesius are soluble in alcohol. Rosin, the most important, is 
 obtained from the pines of the southern United States and else- 
 where. 
 
 Several fossil gums are used in cnnsideri'.ble quantities. While copal 
 is yielded by trees now growing, most of it is obtained in the sand where 
 trees once grew. Madagascar and Zanzibar produce the greatest quan- 
 tities. Dammar is another fossil resin, the product of certain coniferous 
 trees of Australasia. Amber is a fossil gum, found mainly in northern 
 Europe. It is believed to occur in regular veins along the Baltic coast; 
 large quantities, detached by the force of the waves, are thrown upon 
 the shores during heavy storms. It is also met with inland, and niiues 
 are worked in certain localities. Insects belonging to extinct species ai'e 
 often found incased in amber. 
 
 Rubber, or caoutchouc ikoo'chook), is the thickened and hardened 
 milky juice of various trees, natives of South and Central America, 
 southern Asia, and equatorial Africa. The sap of caoutchouc-bearing 
 trees, when rubbed between the fingers, coagulates into an elastic fiber. 
 Synnneti-ical balls made of this material were used in playing a certain 
 game by the natives of Haiti at the time of the discovery of the island 
 by Columbus. During the dry season, between August and February, 
 the gum-trees are tapped in South America. The milk flowing from 
 the incisions' is collected in shallow cups of clay, the average yield 
 of juice for a tree being two ounces a day. The juice yields about 
 tiiirty per cent, of its weight in caoutchouc, which is prepared in 
 flat, rounded cakes ("biscuits"). Mozambique rubber occurs in balls 
 about the size of an orange. Many million pounds of gum are annu- 
 ally consumed in making various appliances used in the arts and manu- 
 factui'es. 
 
 Plants yieldiiiff Narec)tics. — r)f these, the most impor- 
 tant are the tobacco and opium po[>py. 
 
 Tobacco is an annual plant of the potato family, native to 
 America, and was smoked l)y the Indians when the continent 
 was first visited by Columbus. It was introduced into England 
 by llaleigh in 1589, though earlier known to the Spanish and 
 French. It is lunv cultivated throughout the tropical and tem- 
 perate zones. 
 
 Opium is the dried juice of the seed-pods of a species of poppy. In 
 parts of Asia, and by the Chinese of America, it is chewed and smoked 
 to produce intoxication. Opium and its alkaloid morphine are largely 
 used in medicine to induce sleep. The plant is believed to be native to 
 the Mediterranean region. 
 
 Belladonna, or deadly nightshade, is a tall, bushy plant of the potato 
 family, bearing a highly-poisonous but attr'active-looking fruit. Prepa- 
 rations of belladonna and its alkaloid atropine are used in medicine as 
 anodynes ; they are of gi-eat service in the treatment of certain diseases 
 of the eye, on account of their peculiar property of expanding the pupil. 
 (Consult Smith's ''Dictionary of Economic Plants") 
 
 \ 
 
 "-^ 
 
 Belladonna and the Opium Porpv. 
 
 Questions. — Name the different classes of plants most important to man. 
 What do food-plants comprise ? Define cereals. Which is the most im- 
 jiortant and why ? What can you say of wheat ? Rice ? Millet ? Indian 
 corn \ Rye ? Buckwheat ? Wliat is meant by tuberous plants ? Give 
 an account of the iirincipal members of this group ; of the ckief fruit- 
 bearing plants ; of the plants bearing succulent stems and leaves. 
 
 For what are plants that yield fibers useful ? Describe cotton. How many 
 varieties of the cotton-plant are recognized by botanists ? What is hemp, 
 and for what is it used ? Flax ? .Jute ? State the habitats and uses of 
 the principal timber-trees. Explain the economic value of forests. 
 
 What is sugar ? Describe the process of its manufacture. Whence is quinine 
 obtained ? Where are cinchona- trees successfully cultivated ? What are 
 the medicinal properties of coca % What are teas, and from what plants 
 are they made ? Describe the coffee tree and bean. Name the principal 
 dye-plants ; the spice-plants ; the plants that produce oils and gums ; the 
 most important narcotics. 
 
 Note. — The student who is interested in the subjects of plant-structure and plant- 
 life should secure an inexpensive microscope, and prosecute his studies in the highways 
 and fields. A multitude of beautiful and instructive forms will be found on every side 
 — cells and cell-contents, pollen of ditferent shapes and markings, dcsmids and algae, 
 spores on the leaves of ferns, mosses and molds growing on various bodies, plant- 
 crystals, starch-granules, etc. — all evincing exquisite workmanship and wonderful design. 
 Many of the illustrations in this chapter have been drawn directly from the microscopic 
 field. (For fuller and most interesting information, read Dr. Hogg's " Tlie Jficroscope ; 
 Us Hislorg, Constructinn, and Apptieation" pp. S55-S65 ; and Dr. Stakts's "Microscopy 
 for Beginners, or Cotnmon Objects from the Ponds and Ditches" chap. Hi. ) 
 
ANIMAL LIFE ON THE EARTH. 
 
 i V SBSaa^SL; 
 
 tf^lS>i~r- 
 
 ^\f^_ 
 
 Several varieties of protozoa are il- 
 lustrated in the engraving. Fig. 1 
 belongs to the order Radiolaria; the 
 framework of the body consists of radi- 
 . ' ating spines. Fig. 2 is a Stentor, or 
 
 trumpet-anirDalcule, a common infusorian. 
 Figs. 3 and 4 show adult colonies and sin- 
 gle specimens of the flower-like Flagellata. 
 Figs. 6 and 1 represent forms of Fo-ram-in- 
 if'era, or Rhiz'opods whose bodies are pro- 
 tected by joej/orafec? limy shells. Fig. 8 is the 
 Amoeba, or Proteus animalcule, containing a nucleus 
 whose functions are not known, a circulatory organ 
 called " the contractile vesicle," and " food-spaces." 
 (See Professor Lankester''s illiistrated article on Pro- 
 tozoa, '■^ Encyclopcedia Britannica," vol. zix., p. 830.) 
 
 Prim.^ky Groups. 
 
 I. Protozo'a (fird, i. e., lowest, animals). 
 
 II. Porif'era (pore-bearing animals). 
 
 III. Civlentera'ta (having hoUoio intestines). 
 
 IV. Echinoder'mata (animals with sjdne-cov. 
 
 ered skins). 
 V. A^ermcs (u'orms). 
 
 VI. MoUuscoid'ea (moHusk-lihe animals). 
 VII. MoUusca (mollusks, soft animals). 
 VIII. Arthrop'oda (animals "ha^mg jointed bod- 
 ies and appendagci). 
 IX. Tunica'ta (ajiimals clothed with a tunic 
 or envelope). 
 X. Leptocar'dii (having no distinct heart). 
 XI. Marsipobran'chii (having gill-sacs). 
 XII. Elas'mobranchii (having gill-ponches). 
 
 XIII. Pisces (fshes). 
 
 XIV. Dipnoi (double-breathers, i. e., having 
 
 gills and lungs). 
 Xy. Batra'chia (frogs). 
 XVI. Reptiria (reptiles). 
 XVII. A'ves (birds). 
 XVIII. Mammalia (that sucMe their young). 
 
 Protozoa. 
 
 Animals 
 
 constitute 
 the second 
 great divi- 
 sion, or "Kingdom," of 
 organic nature. 
 
 The distinction be- 
 tween plants and animals 
 is sufficiently clear in the 
 groups ; but, in 
 the case of many of the 
 lower forms, it is difficult 
 and often impossible to 
 determine to which of the 
 two kingdoms an organ- 
 ism belongs {see p. 88). 
 
 Zoology. — The sci- 
 ence that treats of ani- 
 mals, their structure, hab- 
 its, and classification, is 
 called Zoology (from the 
 Greek zoon, an animal., 
 and logos, a discmirse). 
 In order to study objects 
 In the animal kingdom, 
 because sharp distinctions 
 
 Classification of Aninials.- 
 
 intelligently, they must be classified. 
 
 classification is necessarily arbitrary, 
 
 between groups rarely exist, except where wide gaps have been 
 
 left by the extinction of intermediate forms. 
 
 It was formerly the practice to class all animals under the four divis- 
 ions — Radiates (having their organs arranged radially about the axes 
 of their bodies ; often star- or flower-shaped), Mollusks (with fleshy 
 bodies, usually protected by shells). Articulates (composed of joints with- 
 out internal skeletons), and Vertebrates (having an internal skeleton 
 and spinal cord). But the rapid progress recently made in natural 
 science has demonstrated the necessity for a different and more compre- 
 hensive system. Still, owing to the incompleteness of our knowledge of 
 the hfe-histories of many animals, a perfectly satisfactoiy classification 
 has not yet been attained. The following may be considered to repre- 
 sent the present state of knowledge on the subject, so far as the primary 
 groups are concerned : — 
 
 The Protozoa comprise the lowest forms of animal life, 
 many of them being single, isolated cells ; they are all of small 
 size. Among the groups into which the Protozoa have been 
 divided are the Rhizopods {riz' o-j)ods, root-footed animals, from 
 their power to jjrotrude at will, from different parts of their bod- 
 ies, extensions of their substance called " false feet ") ; and the 
 Infuso'ria (so called because they are generated in infusions left 
 exposed to the air). 
 
 The Ehizopods form vast deposits in many parts of the ocean, both 
 at great deiJths and along the shores; some of the fossiliferous rocks 
 consist almost wholly of the remains of graceful shell-bearing species. 
 The Infusoria abound both in salt and in fresh water, and are interest- 
 ing objects of study under the microscope. Some of them are so diminu- 
 tive that 30,000 have been counted in a half-ounce of sand. 
 
 The Porifera comprise the sponges. Some of these are 
 characterized by a deposit of lime in their bodies ; others, includ- 
 ing the sponges of commerce, by a fibrous or horny structure. 
 Still others are remarkable for the silicious depo.sits they contain, 
 and are hence called glass sponges. The beautiful " Venus's 
 flower-basket "' is a glass sponge. 
 
 Dry sponges are the skeletons of sponge-animals. " At the bottom 
 of the warm seas on the Mediterranean coast or in the Gulf of Mexico, 
 these sponge-animals live in wild profusion, sometimes hiding in sub- 
 marine caverns, sometimes standing boldly on the top of a slab of rock, 
 or often hanging under ledges. Some are round like cups, some branched 
 like trees, some thin and spread out like a fan ; while there is hardly a 
 color, from a brilUant orange to a dull, dingy brown, which is not to be 
 seen among them." Sponge-colonies are visited once in three years by 
 trained divers, who tear the adult specimens from their rocky beds, 
 and subject the skeletons to bleaching and purifying operations. (On 
 sponges and how they live, see Buckley^s "'Life and her Children,^'' 
 pp. S3-49.) 
 
 The Coelenterata comprise the jelly-fishes, sea-anemones, 
 and coral polyps. Many of them are brilliantly colored, and are 
 among the most beautiful objects to be found along our sea-shores. 
 
 One variety., the Portuguese mau-of-war, is a common object in ti-op- 
 ical waters. The sea-anemones (a-nem'o-nes) are fleshy polyps, which, 
 from their supposed resemblance to flowers, were called zoophytes, or 
 plant-animals (see p. 30), by the older naturalists. (On the Ccelenterata, 
 consult Professor Dana^s '^Corals and Coral Islands.^') 
 
MOLLUSKS AND FISHES. 
 
 101 
 
 Tlie Ecliiiiodoriiiata comprise the 
 eriiioids (represeiitud by few living species, 
 hut enormously abuudimt in tlie past, as evi- 
 ilcnced by their remains in some of the fossil- 
 bearing rocks — .sYf p. IJf), the serpent-stars, 
 the star-tishes, the sea-urchins, and the sea- 
 rncunil)ers {see p. 102). The tough, leath- 
 ery bodies of the latter, under the name of 
 " trei)aug," are eaten by the Chinese. {See 
 Agassis's "Sea^side Studies.'-) 
 
 The Molliisca embrace the laud aiul 
 sea snails, l)ivu]ve-shells, slugs, cuttle-Hshes, 
 and the beautiful nautilus and argonaut {see 
 p. lOii). They are divided into three groups : 
 the first includes mussels, clauis, and oystei's ; 
 the second, snails, slugs, limpets, periwinkles, 
 and all s])iral shells ; the tiiird, cuttle-fish, 
 squids, and the nautilus, the only living repre- 
 sentatives of the ammonite group that once 
 filled the primeval ocean {p. 15). (On ani- 
 mals of this group, and shells, consult ^ood- 
 loord's '■^3/0)1 If al of the ^folluscaP) 
 
 Molhisks supply many articles of great com- 
 mercial importauee. Pearls and portions of cer- 
 tain shells are much prized as jewels and parlor 
 onunuents ; and oysters, clams, scallops, periwin- 
 kles, and (jther species, are largely used a.s food. 
 The oyster industry alone is one of great magni- 
 tude. In the United States, in 1890, according to 
 the official census, more than 50,000 persons and 
 4,000 vessels were employed in the oyster fishery ; 
 the annual yield sold for over $15,000,000. 
 
 The Arthropoda comprise invertebrate 
 animals with jointed legs, such as cnistaceans 
 (barnacles, shrimps, crabs, and lobsters), ceu- 
 tipeds, spiders and scorpions, and all insects ; 
 the Tuiiicata, animals which, though re- 
 sembling: some of the lower organisms in ex- 
 ternal appearance, are really highly organized, 
 and are proliably the iuunediate predecessors 
 of vertebrates ; the Leptocartlii, hut a sin- 
 gle genus, the laucelet, which is the lowest 
 known vertebrate. Tlie laucelet is from one 
 and a half to two inches in length, and has no 
 distinct head or lateral appendages. It inhab- 
 its shallow ]5ortions of the sea where the bot- 
 tom is sandy, and is found along our own 
 coast from the mouth of Chesapeake Bay to Florida. 
 Primary Groups, compare Dr. Pacl-ard\i '■'■ZoologyP) 
 
 The 3Iarsipobraiichii include the hag-fish, or borer, and 
 the 1 am]) rev-eel ; the former inhabiting muddy bottoms at consid- 
 erable depths in the sea, the latter living both in fresh and in salt 
 water. Both feed on other fish. The lamprey fastens on its vic- 
 tims, and sucks their blood at its convenience. The hag-fish buries 
 itself in their fiesh and abdominal cavities. 
 
 The Elasiuobraiichii comprise the sharks, skates, rays, tor- 
 jiedo, saw-fish, devil-fish, and cliime'ra. They have been character- 
 ized as " engines of destruction, having been since their early ap- 
 pearance, in the Upper Sihtrian Age, the terror of the seas. Their 
 structure is such as to enable them to seize, crush, and rapidly digest 
 large invertebrates, and the smaller members of their own class." 
 
 CCELENTERATA. 
 
 (On these 
 
 1. Tortuguese man-of-war. 
 
 2, 3. Coral polyps. 
 4 to 10. Sea-anemones. 
 11. Jelly-fish. 
 
 Sharks are most abundant 
 iu the seas between the tropics, 
 but few kinds being found in 
 Arctic watei-s. One formidable 
 species is known to attain a 
 length of 40 ft. Sharks' tins are 
 a favorite article of food with 
 the Chinese; they ai-e also used 
 in the manufacture of gelatine. 
 At Kurrachee, India, there is a valu- 
 able shark-fishery; forty thousand fish 
 are taken annually for their fins. (Con- 
 sult Dr. Gunther's "Ah Introduction 
 to the Study of Fi.'<hes." p. .116.) 
 
 The torpedo, or electric ray, is a very 
 remarkable fish. It possesses a pair of 
 large electric organs, constructed on the 
 principle of the voltaic pile. In the 
 American species there are about elev- 
 en huncb'ed cells in each battery — more 
 than double the number present in the 
 European. These batteries are under 
 the control of the animal, so that at 
 will the torpedo is capable of adminis- 
 tering a powerful shock, either in self- 
 defense, or for the purpose of disabling 
 its prey. 
 
 The Pisces, or true fishes, 
 comprise a vast variety of forms in- 
 hal)iting the seas, rivers, lakes, and 
 streams, of all parts of tlie world. 
 They vary in size, from species only 
 an inch in length to those weighing 
 many hundreds of poimds, and sup- 
 ply a large and important part of the food of the human race. 
 {Read Goode's '■^The Fishei'ies and Fishery Industries of the 
 United States.'") 
 
 The artificial propagation of fishes has become an important industry 
 both in Europe and America. The possibility of successfully hatching 
 ova and of stocking barren watei-s with valuable food-fishes has been 
 demonstrated, so that most of our states and territories have appointed 
 commissioners to protect and develop their fisheries. The government 
 also has establislied a fisli commission. (Stuulard authorities on fish- 
 culture are Green and Rooserelt'.s ''Fi.^h-Hatcliing and Fisli-Cafching," 
 Livingston Stone^s "Domesticated Trout,'' and Maifhnurs "The His- 
 tory of Hou-ietoun.") 
 
 The Dipnoi are remarkable fish-hke animals, possessing both 
 gills and lungs. They are thus enabled to exist in pools which 
 become dry in summer. The Dipnoi are a very ancient group, 
 
102 
 
 BATRACHIANS. — REPTILES. — BIRDS. 
 
 ff^'/^y 
 
 iu many respects 
 are intermediate be- 
 tween the Ganoid fish- 
 es (with hard, hriglit 
 scales, the sturgeon being 
 a representative) and the Ba- 
 ti'achians. 
 The Batracliia, or Amphibia, 
 comprise the frogs and toads ; the 
 salamanders and newts; the proteus, the men'- 
 obranchus, and the siren or mud-eel of the Sonth 
 Carolina rice-swamps ; and the so-called hell-bender 
 or mud-devil of the Ohio Hiver, and the blind-worm. 
 The young of these animals undergo a transformation 
 or metamorphosis before arriving at maturity. They live in water, 
 and are provided with external gills ; while, as a rule, the adults 
 breathe by means of lungs, and live on land. 
 
 The Reptilia comprise the snakes, lizards, turtles, and croco- 
 diles. Most of them dwell upon land, and all are air-breathing. 
 They are most abundant in the tropics and warm-temperate re- 
 gions. A vast number of fossil reptiles have been discovered, 
 among which the great flying Pterodactyls {see p. H) are among 
 the most remarkable. Another fossil group is intermediate be- 
 tween reptiles and birds. 
 
 The Aves, or Birds, are highly specialized animals which 
 bear feathers, and as a rule are adapted for locomotion in the air. 
 They constitute a very distinct and at present a very circumscribed 
 group, though fossil forms have been found which indicate close 
 relationship to reptiles. A number of extinct birds with teeth 
 have been discovered, and one, the ArchcBop'teryx {ancient wing), 
 had a long bony tail with feathers on both sides {see diagram, pp. 
 12 and 13). 
 
 All existing birds may be subdivided into three principal 
 groups : the first includes the ostriches, cassowaries, moas, and 
 tin'amous of Guiana and Brazil ; the second, the penguins ; and the 
 third, all other species, viz., grebes, auks, gulls, petrels, snipe, 
 ducks, pelicans, grouse, pigeons, birds of prey, parrots, humming- 
 bii'ds, swallows, finches, thrushes, etc. Many birds are remarkable 
 for performing extensive biannual flights or migrations, which 
 enable them to spend the summer seasons in regions hundreds of 
 
 miles north of their winter homes. {Consult liidg. 
 ioay\s '■'■Manual of North American Birds.") 
 
 ^ Birds are of very great economic importance to 
 man, and yet their services are so little appre- 
 -^'=5r.' ciated that many of them have been slaughtered 
 'iT by hundreds of thousands, chiefly for milli- 
 ,, '■ nery purposes. Some species have been actu- 
 V <5s '•' " ally extermmated, and many have been made 
 
 rare where formerly they were abundant. Be- 
 sides the birds that are killed for decorative pur- 
 poses, others are destroyed in the belief that they 
 are injurious to the interests of mankind, while in reality they are bene- 
 ficial. Hawks and owls are marked examples of this class. .Their raids 
 upon the poultry-yard are insignificant in comparison with the good 
 they do in checking the increase of mice and noxious insects, which con- 
 stitute their principal food. 
 
 Other species have been hunted for the market, until in certain 
 regions they have become extinct. The great auk, once abundant on 
 the northern coasts of America, no longer exists; the wild pigeon has 
 almost disappeared ; the wild turkey is passing away ; and the pinnated 
 
 grouse, or prairie- 
 
 hen, has been ex- 
 terminated in the 
 Eastern States, and 
 has become scarce 
 in western sections 
 where it was once 
 abundant. Most of 
 our states and terri 
 tories, in common with 
 the European govern- 
 ments, have placed their game 
 song, and insectivorous biids un 
 der the pi'otection of the laA\ The 
 enforcement of game-laws, mak 
 Log it unlawful to destroy valu- 
 able birds and quadrupeds at cer- 
 tain seasons of the year when 
 they are rearing their young or 
 are otherwise rendered defense- 
 less against poachers and mai-ket- 
 hunters — as well as of non-export 
 laws that i*emove the inducements 
 to kill for "out-of-state" markets 
 —has invariably resulted in a phe- 
 nomenal increase of the native 
 fauna. (On the economic uses of 
 birds, consult MarsKs " Man and 
 Nature" p. 57.) 
 
 The Maiiiinalia comprise 
 the warm-blooded, air-breathing 
 vertebrates which suckle their 
 young, and whose bodies, at 
 some period of their exist- 
 ence, are more or less 
 coated with hair — the 
 normal covering of the 
 group. The young are 
 generally born alive. 
 The living representa- 
 tives of the mammalia 
 fall naturally into 
 three major groups : Oi- 
 nithodelphia, Didelpliia, Mollusca. 
 
 and Monodelphia. The j. Nautilus. 2. Pond-snail. 3. Sea-slug, 
 
 first of these consists of the 4. Volu'ta. 5. Octopus. 
 
GEOGRAPHICAL DI ST li I R t' T I () N OF ANIMALS. 
 
 10.3 
 
 duck-billed platypus, or ornithorliyn'chus, and the echidna 
 (e-kid'na), or porcupine ant-eater, both of wliich are coiitiued 
 to the Australian region. They are the lowest of niainmals, 
 and in many respects are intermediate between mammals and 
 reptiles, with which latter class they share many striking pe- 
 culiarities. They differ from all other mammals in lieing 
 ov/'jM/'ous, which means that they lay eggs. The echidna 
 places her eggs in two little abdominal pouches, and cairics 
 them about with her till they hatch ; while the ornithorhyu- 
 chus sits u])on her eggs after the manner of a hen. 
 
 The Didelphia, or Marsupials (from a (ireek word mean- 
 ing haij or jnirse), are distinguished by having, among other 
 peculiarities, an abdouiinal pouch in which the young, l>orn 
 in a very rudimentary and helpless comlitiou, are cari'ied till 
 able to care for themselves. Excepting the opossums, which 
 are fouTid in America, the ]\Iarsupials are confined to Aus- 
 tralia, Xew Zealand, and New Guiuea. 
 
 The Monodelphia occur in all parts of the world, and are modi- 
 tied for habits of life in the water, on land, in trees, and in the air. 
 This group contains, among others, cattle and horses, sea-cows and 
 whales, squirrels, bats, lions and tigers, seals, apes, men. 
 
 ECHINODERMATA. :? V^ 
 
 1. Star-fish. 2, S. Crinoids. 
 
 4. Serpent-star. 
 6. Sand-dollar. 
 
 5. Sea-urcliin. 
 1. Sea-cucumber. 
 
 GEOGRAPHICAL DISTRIBUTION OF MAMMALIA. 
 
 Faiinal Realms. — Animals, as well as plants, are influenced 
 in their dispersion l)y climatic and physical conditions, among 
 which may be mentioned temperature, humidity, elevation above 
 sea-level, and character of soil. The result of these sevei'al influ- 
 ences, acting singly or in combination, is that the various species 
 are not diffused e(|ually in different directions, but are restricted to 
 certain well-defined are;us as thoroughly as if limited by impassable 
 physical barriei-s. Hence it becomes possible to divide the surface 
 of the earth, according to the distribution of its animal inhabitants, 
 into a number oifdmuil rct/t'cnis or provinces. 
 
 Temperature, clearly, is the most potent factor in determining 
 the boundaries of the principal divisions or realms. For this rea- 
 son, life is distributed in zones whose boundaries are not coincident 
 with the parallels of latitude, but generally with the isotherms. 
 
 The primary divisions or " Realms," according to Allen, are the fol- 
 lowing : — 
 
 I. Arctic, or North Circumpo- | V. Iiulo-Africaii. 
 
 lar. 
 II. North Temperate. 
 
 III. American Tropical. 
 
 IV. South American Temperate. 
 
 VI. Australian. 
 VII. Lenuirian. 
 
 VIII. Antarctic, or South Circum 
 polar. 
 
 (On the Geographical Distril)ntion of Mammalia, .see an important 
 paper by J. A. Allen, in " Bulletin of the United States Geological and 
 Geographical Surrey" rol. ir.. No. 2, ISTS.) 
 
 The Arctic, or North Circunipolar, Realm embraces 
 the ice-clad and barren lands <if America, Siberia, and (Greenland, 
 and extends southward to the northern limit of trees, or approxi- 
 mately to the i.sotherm of 32° Fahr. It is renuirkable for the 
 polar bear, musk-ox, Arctic fox, and lemmings (small animals re- 
 sembling our meadow-mice) ; and in its seas dwell the walras, nar- 
 whal, white whale, and many seals. Myriads nf water-birds rear 
 their young within its borders. 
 
 The North Temperate Realiu extends from the southern 
 boundary of the Arctic Realm to the isotherm of (58° or 7(»° F., 
 
 thus endjracing North 
 America as far south 
 as Mexico, Central 
 Asia, Eurojie, and northern Africa, 
 is the home of the fur-bearing animals, 
 such as the fiu--seal, sea-otter, otter, sable, 
 mink, fisher, beaver, and ermine ; also 
 of the lynxes, wolves, foxes, badgers, and 
 bears : of the moo-se, elk. reindeer, bison, 
 and pronghorn-antelope ; of tlie moles 
 and shrews; of fi}"ing and other squir- 
 rels; of the prairie-dogs and marmots. 
 
 The American Tropical 
 Realm is included between the iso- 
 therms of 70° north and south. Its 
 southern limit may be indicated by a 
 somewhat irregular line passing north- 
 westward from the southeastern comer 
 of Brazil to northern Peru. Thus the 
 American Tropical Realm comprises 
 southern Florida, the West Indies, Mexi- 
 co, Oentral America, and the northern 
 half of South America. The characteris- 
 tic mammals are — the spider- and howl- 
 ing-monkeys and marmosets; the coa'tis 
 (closely related to the raccoon) ; the jaguar, ocelot, and civet-cat ; 
 the American tapir and the peccary ; the manatee, or " sea-cow," 
 bunted for its fiesh, oil. and hide ; the capy'bar'a, cavy, and agouti, 
 varieties of rodents or gnawers ; leaf-nosed brfts; armadillds (armor- 
 plated, bun-Dwiug animals), ant-eaters, sloths, and opossums. 
 
 Tlie South American Temperate Realm embraces 
 the southern half of South America and the adjacent islands on the 
 east and west. It is the home of the peculiar South American 
 deer, of the llama, guanaco, chinchilla, and spectacled bear. 
 
 The Indo-African Realm covers tropical Asia, and Africa 
 south of the central portion uf the (Ireat Sahara Desert. 
 
 The Indian Region includes the Malay Peninsula, Sumatra, 
 Java, liorneo, Celebes, the Philippine and Snnda Islands, and For- 
 mosa. The most remarkable animals are the orangs, the gibbons 
 or long-anned monkeys, the le'murs (animals with a fox-like muzzle 
 resend)ling monkeys) ; certain biits; the Bengal tiger, the Indian 
 elephant, and rhinoceros ; wild cattle (from which the zebu was 
 domesticated) ; the babyroussa or " hog-deer,'" and the axis deer. 
 
Questions on the Map of Faunal Realms. — What advantages have 
 
 animals over plants in distributing themselves? Note the limits of the great faunal 
 regions, and name the characteristic mammals of each. To what parts of the world 
 are the larger carnivora confined ? Where do you meet with the monkey ? In what 
 respect does it differ from man in distribution ? To what part of Africa is the gorilla 
 limited ? For what class of animals is South America chiefly remarkable ? Australia ? 
 Madagascar? Where does the alligator abound? What great serpent infests the 
 forests of Brazil? What African river is the home of the crocodile? Mention coun- 
 tries almost without reptiles. 
 
 Show that the distribution of land-animals in vertical space depends on certain laws 
 of climate. Of the fishes noted in the map, which are used for human food ? Where is 
 the electric eel found ? the cuttle-fish ? the spermaceti whale ? What waters are inhab- 
 ited by the walrus ? the seal ? What fish are taken off the coast of Norway ? in the 
 river Volga and the Caspian Sea ? off Newfoundland ? in the Mediterranean ? Where 
 are sponges found? valuable mollusks? Mention an important group of birds peculiar 
 to Africa. What birds are essentially American ? Where are song-birds chiefly met 
 with ? eider-ducks abundant ? What bird is peculiar to New Zealand ? The apteryx 
 {wingless), having partially developed wings. Illustrate the wide range of certain birds. 
 
TZBERQt* 
 
106 
 
 FAUNAL REALMS. — ANIMAL PRODUCTS. 
 
 The African Kegion is inliabited by the huge apes, the gorilla 
 and chimpanzee ; the true baboons ; hyenas ; the African Hon, the 
 African elephant, and rhinoceros ; camels, giraffes, and zebras ; the 
 gnu and the African buffalo; numerous antelopes; the hippo- 
 potamus ; the hy'rax (a gregarious little animal living in holes 
 among the rocks and believed to be identical with the " coney " 
 of the Bible) ; the Cape ant-eater ; and the ma'nis (from a Latin 
 word, meaning ghosts, so called from its habit of seeking food by 
 night) or scaly ant-eater, whose body, limbs, and tail, are protected 
 by an armor of overlapping horny plates. 
 
 The Australian Realm comprises Australia, Tasmania, 
 New Guinea, New Zealand, the Moluccas, Arru, and the Solomon 
 Islands, Polynesia, and the smaller interven- 
 
 It is the home of the duck-billed ornitho- 
 rhynchus, various forms of the echidna, '^■^ 
 and of the Marsupials or pouch bearers, 
 which are the predominating 
 and almost exclusive mamma- 
 lian inhabitants of Australia, 
 Tasmania, and New Guinea. 
 To the latter group belong 
 the kangaroos, the wombat, 
 the koala (ko-ah'la), or little 
 native bear, the bandicoot (a 
 small, rat like animal, very de- 
 structive to crops), the pha- 
 langer (or Australian opos- 
 sum), the Tasmanian devil (a 
 small but ferocious mammal, 
 allied to the native wolf), and 
 the pouched dog. The dingo, 
 or wild dog of Australia, is 
 not a marsupial, but a true 
 canine. 
 
 The Lemurian Realm 
 consists of Madagascar and 
 the Mascarene Islands. In its 
 animal life it is very distinct 
 from all other portions of the 
 earth. It is the home of a 
 large number of peculiar and 
 beautiful lemurs ; of a unique 
 carnivorous family ; and of an 
 insectivorous group, only a 
 single representative of which 
 (a native of the "West Indies) is 
 found in any other part of the 
 world. (See Stanford^ s '•'• Corti- 
 pendium of Geography P^ 
 
 The Antarctic Realm embraces the South Polar region, 
 and extends northward far enough to include Tierra del Fuego and 
 the Falkland Islands. It is mainly oceanic, but contains the few 
 small groups of Antarctic islands. Hence, its characteristic mam- 
 mals are dwellers in the sea, and most of them are of commercial 
 importance. Among them may be mentioned the gi-eat sea- 
 elephant, which is the largest of the seals, and certain whales and 
 porpoises. 
 
 The larger Eealms are divisible into regions, provinces, and faimcB. 
 For example, the North-Temperate Eealm is divided into a North 
 
 Batrachians. 
 1 . Salamander (a name given to most of the batia- 
 chians with persistent tail, but whose gills disappear at 
 maturity). 2. Menobranchus, or the iish-lizard, whicli 
 retains its gills through life ; two species inhabit the 
 fresh waters of the United States, 'i. Amblystonia, or 
 spotted eft ; one species burrows in the ground. 4. Lar- 
 val (immature) salamanders. 5. Flying tree-toad. 
 
 American Reg-ion and a Europeo-Asiatic Region ; the North American 
 Region in turn is divided into three provinces — an Eastern, Middle, and 
 Western. Again, each of these provinces is capable of subdivision into 
 faunal areas or faima;. In the Eastern Province, the following have 
 been characterized : Floridian, Louisianian, Carolinian, Alleghanian, 
 Canadian, Hudsonian, and Arctic, each of which has its distinctive 
 animal inhabitants. 
 
 Economic Uses and Products. — Except in the tropics, 
 it is doubtful if man could exist, either in the barbarous or civil- 
 ized state, without making use of the lower animals. 
 
 Several kinds of mammals are of inestimable value as beasts of 
 burden. The most important are horses (including mules and 
 donkeys), cattle, camels, elephants, llamas, reindeer, and dogs. 
 
 A lai'ge and essential 
 part of the food-sup- 
 ply of the various 
 races of man 
 is derived 
 \, from the 
 mamma- 
 lia. Meats (both 
 fresh and salt), 
 fats, lard, milk, 
 butter, and 
 ; cheese, fall un- 
 ' der this head. 
 
 •^4 Eoth savage and civilized 
 
 J man diaw largely upon the vari- 
 l' ous gioups of mammals for their 
 clothing, and for the articles in ev- 
 eiy-da;y use. Among the raw mate- 
 iialb thus constantly employed are 
 hides (tumibhing leather of all kinds), 
 pelts, fuis, wool, hair, bristles, silk, 
 ivoiy, whalebone, horns and hoofs, bones, 
 tallow, oils, and manures. {Consult Sim- 
 -/ monds^s ^'■Animcd Products.''^) 
 
 Questions. — Illustrate the wide distribution of life upon 
 the earth. State the principal diflferences between plants 
 incl animals. How do plants breathe ? In what different ways 
 do animals breathe ? Show how jilants consume the poisonous 
 ]iroducts of animal respiration. What is zoology ? Can you name 
 the subdivisions of the animal kingdom, explaining the appropri- 
 ateness of each designation ? Describe the protozoa. "What are 
 foraminifera ? Infusoria ? What is their range ? How do sponges 
 live ? What creatures do the Coelenterata comprise ? Describe 
 the jelly-fish ; the sea-anemones. What animals are included un- 
 der the head of Echinodermata ? of Mollusca ? of Arthropoda ? of 
 Elasmobranchii ? Give some interesting facts regarding sharks; 
 the torpedo; the economic value of mollusks. 
 What provision is made for the protection and propagation of oar 
 food-flshes ? Why are such steps Uecessary ? What can you say 
 of the Batrachia ? of the Reptilia ? of birds and their economic 
 uses ? Into what groups have the Mammalia been divided ? Name the 
 chief marine mammals. Have you observed whether our salt-water fishes 
 are capable of adapting themselves to fresh water, and vice verm ? Give 
 examples of species of animals that have become extinct within the his- 
 toric period {seep. 15); of others now dying out. {Read Harfing''s "Brit- 
 ish Animals Extinct within Historic Times.'''') How only can the threatened 
 extermination of many of our most valuable game-birds and beasts be 
 averted ? Define the duty of every citizen in this respect. 
 How far are the flora and fauna aflected by climate ? by differences of level ? 
 What has been the influence of man on the distribution of animals ? Into 
 what faunal regions has the surface of the earth been di\dded ? Mention 
 the characteristic fauna of each. Describe some animal products. 
 
THE HUMAN FAMILY, 
 
 Man, though separated from the rest of the animal kingdom 
 hy tlie possession of spiritual and superior mental attributes, is 
 related to the lower animals in physical structure and anatomical 
 characters. Zoological classitication being based upon these feat- 
 ures, man finds a place in it, though at the highest point in the 
 series. {See Iluxleijs ^''Manx Place in Nature^) 
 
 In the nomenclatiu-e of zoology, Man {Homo) forms the smgle spe- 
 cies Homo sapiens (or the tcise), belonging to the family Hominidse 
 (mankhid), and the order Primates, which also mcludes the highest or 
 man-hke apes. (See R. Hartmaii's ''Anthropoid Apes,''' '■'International 
 Scientific Series." No. 52.) 
 
 Besides his merely zoological standing as one among other liv- 
 ing beings, man is subject to classification in as many ways as there 
 are natural groups of relationships growing out of his physical, 
 social, political, and spiritual characteristics. On these are based 
 division into races, families, towns, states, and nations, and religious 
 organizations — the study of which gives rise to various sciences 
 more or less intimately related. 
 
 The science relating to mankind in the widest sense, including all 
 the others, is known as Anthi'opology (from anthropos, man, and logos, 
 a discourse) ; that relating to the races of mankind is called Ethuologj' 
 (from ethnos, a people, and logos) ; that treating of the social relations 
 between individual members of the human species is Sociology. 
 
 Mankind is classified by Types, Races, and Peoples, as 
 regards physical characteristics ; and has become organized into 
 nations, states, tribes, and other political groups, through the neces- 
 sity for mutual protection, for the regulation of common interests, 
 and for the preservation of the rights of individuals. 
 
 These organizations are of slow growth. The stage they have reached 
 witli any particidar people corresponds to our idea of the progress of 
 that people from savagery toward ciWlization. From history we know 
 that the highest civilization of one age is, on the whole, of a lower gi-ade 
 than that which is afterward reached ; so that civilization and enlight- 
 enment are progressive terras. Progress is gi-eatly dependent upon in- 
 telligence, energy, and morality. But the physical charactere by which 
 man is classified are independent of his will or purpose, and seem to be 
 derived from his original constitution. The fundamental idea of a race, 
 therefore, is quite different from that of a nation. 
 
 A Type is an ideal standard ^vith certain well-defined charac- 
 teristics, to which individual human beings approach more or less 
 nearly ; and by comparison with which their general physical rela- 
 tions are determined or measured. A Race is composed of typi- 
 cal people related by blood and transmitting the race-characters to 
 their descendants. A People is an assemblage such as we find 
 actually existing in the world, where there are always some devia- 
 tions from any specified type and some mixture of races, resulting 
 from the constant intercourse of human beings belonging to differ- 
 ent types and races. 
 
 While the type and race can be defined with precLsion, it is found iu 
 practice that the races assigned to a given type actually vary from its 
 sttindard and from one anotlier ; the people composing a race also differ 
 more or less among themselves, and no instance is known of an abso- 
 lutely pure and unmixed race. A Nation is a political assemblage, con- 
 solidated by time and common interest,?, independent of race, and gen- 
 erally containing elements derived from several races ; as in the case of 
 the people of the United States. A race usually has representatives iu 
 several, or even many, different peoples and nations, and, if civilized, is 
 spread widely over the earth. The same race may have representative 
 groups, some in a barbarous, and othei-s in a civilized, state. 
 
 Division into Tyi>es. — There are three types to which the 
 races of mankind are now generally referred, and which are most 
 
 conveniently defined as the White, Yellow, and Black types, foi- 
 merly called the Caucasian, Mongolian, and Negro. The Malay 
 and American groups, once regarded as erpially distinct, are now 
 referred to the Yellow type, of which they form hranches. 
 
 The prevalent color is used to designate the types, for convenience, 
 though the members of each type vary more or less in tint. The most 
 important characters are found in the form of the nose and iu the hair. 
 
 THE BLACK TYPE. 
 
 The Black Type, characterized by frizzly hair and flattened 
 nose, is the least elevated in point of anatomical structure and gen- 
 eral civilization. All its branches originallj' inhabited hot coun- 
 tries. The following table shows the chief races of tliis type, and 
 their distribution : — 
 
 Africa. 
 
 Andaman Isl- 
 andB, etc. 
 
 Australia. 
 
 Tasmania. 
 
 IndoPacific 
 Islands. 
 
 Negroes. 
 Bantu. 
 Nama. 
 Bushmen. 
 
 Negritos. 
 
 Australasians. 
 
 Tasmanians. 
 
 Melanesians. 
 
 The Typical Negroes inhabit Central Africa, especially the 
 Congo basin, and are characterized by frizzly hair, flattened nose, 
 extremely dark complexion, and projecting lips and jaws. Among 
 the principal tribes of this race are the Mandingo, Ashantee, Da- 
 homey, and Kongo people. A group distinguished by peculiarities 
 of language, but physically almost inseparable from the Negroes, 
 are the Bantu peoples, who comprise, among others, the Zulus, 
 Bechuanas, and western Kongo tribes. 
 
 The Nama and Koranna of South Africa, more widely kno\vn as 
 Hottentots, have a less-projecting jaw, are shorter and lighter-colored, 
 and speak a different language from the tj'pical negroes. At present 
 the blood of this race is much mixed, and a pure Hottentot is hardly to 
 be found. They have been great sufferers in war with the Dutch and 
 English of South Africa, and as a race are rapidly passing away. 
 
 The Bushmen, now nearly exterminated, are a small and extremely 
 low race, of little intelligence and marked by peculiar anatomical feat- 
 ures which indicate them as among the lowest examples of hmnanity. 
 They live only in southern Africa, but were probably once widely spread 
 over that continent. (Read Stanford's "Comjjendinm of Geograjjhy ; 
 Africa " ,• Appendix, hy A. H. Keane.) 
 
 The Negritos are an undersized race, represented by the 
 Minkopi of the Andaman Islands, the Sakai of the peninsula of 
 Malacca, and various black mountain-tribes of Formosa and other 
 Asiatic islands. The Minkopi were long considered to be the most 
 degraded of the human family, but a more thorough knowledge of 
 them has shown this opinion to have been based on error. {See E. 
 II. Mans ^^On the Ahoriginal Inhabitants of the Andaman Isl- 
 ands.'") 
 
 The Australasians, who occupy desert or sterile regions, 
 are a tall and meager race, of low intelligence and degraded habits. 
 They are very black, with nearly straight hair and long, narrow 
 heads, small iu proportion to their height. They go in bands with- 
 out permanent habitations, wear hardly any clothing, and devour 
 the most repulsive food. 
 
 The intelligence of this race seems to have culminated in the inven- 
 tion of the boomerang, a flat curved stick which they throw in such a 
 
IDS 
 
 THE TASMANIANS AND MELANESIANS. 
 
 fasliion as to make it return to them after describing a long curve 
 through the air. {Consult Loid's ''Native Tribes of South Australia.'") 
 
 The Tasniaiiians, now extiuct, were a shorter and stouter 
 people, witli more frizzly hair and rounder heads than the Austra- 
 lasians. They inhabited the neighboring island of Tasmania. {See 
 Bonwicl:^s '■'The Lost Tasmanian RaceP) 
 
 The Melanesians, sometimes called Papuans or Black Poly- 
 nesians, inhabit many of the islands in the southwest Pacific, in- 
 cluding Papua or ISTew Guinea and the intei'ior of some of the 
 larger islands, such as Fiji, of which the coasts are occupied by 
 the l)rown race of typical Polynesians. They are (for the most 
 part) violent and ferocious savages, frequently cannibals ; and many 
 of their customs, as well as their color, recall those of certain Afri- 
 can tribes. In a few localities, they have received missionaries 
 and risen somewhat above their primitive barbarism. {See Flow- 
 er, "Journal of the Anthropological Society ^^ London, 1885.) 
 
 There are certain dark people in southern India and Oeylon who 
 have been referred by some authorities to the Black Type of man, but 
 by the majority of writers to the brunette group of the Wliite Type. 
 These are the Dravidians and Kolarians, chiefly distinguished from each 
 other by their respective languages. The former speak a dialect claimed 
 by some writers to resemble the Malayo-Polynesian tongues, while that 
 of the Kolarians is said to have Mongolian features. In all probability 
 these people are the result of a mixture of races. 
 
 The origin of the black races, generally in the most unhealthy re- 
 gions of the tropics, has inured them to climatic influences which would 
 quickly prove fatal to people of other types. It is well known that 
 malarial fevers rarely affect negroes. For this reason, the black races 
 have been invaluable as laborers in malarial regions, such as the site of 
 the Panama Canal and the rich lowlands of the southern United States. 
 The development of the cotton and tobacco industries, which early in its 
 history placed the United States among the great commei-cial nations, 
 could hardly have been effected without the labor of negroes ; and to 
 the forced ti-aining in steady work, which the otherwise evil inistitution 
 of slavery broug-ht upon his predecessors, is doubtless due much of the 
 advance in character and civilization which separates the present Ameri- 
 can negro from the original African, and has given him a creditable 
 place among the free citizens of a progressive nation. 
 
 Questions. — What are the relations of man to other living beings ? What 
 names are applied to man in the classification of zoology ? How else may 
 man be classified ? Name the sciences which treat of mankind in general ; 
 of the races of men, and of their social relations. How is mankind classed 
 
 in regard to phvMcal chai- 
 acters ? Give examples of 
 tlie artificial divisions into 
 which mankind has cigau 
 ized itself. 
 
 What is meant by a Type ? a 
 Race ? a People ? a Nation ? 
 Explain the essential differ- 
 ence between races and na- 
 tions. Mention the three 
 chief types of mankind. What features are used in discriminating them 5 
 
 What are the characteristics of the Black Type, and the distribution of its 
 chief races ? Describe the typical Negroes ; the Hottentots ; the Bush- 
 men ; the Negritos ; tlie Australasians. What part in the development 
 of the United States has been taken by peojjle of the Black Type ? 
 
 THE YELLOW TYPE. 
 
 The Yellow Tyi>e, frequently called Mongolian, is the most 
 widely distributed of all ; its I'epresentative races are found from 
 tlie borders of the Arctic Ocean to the tropical islands of the 
 Pacific, and occupy large areas in Asia and Amei'ica. It is charac- 
 terized by a moderately prominent nose ; a complexion varying from 
 pale olive to dark brown ; straight black hair ; and a skull shorter 
 in proportion to its breadth than in the races of the Black Type. 
 
 In minor characters, the Yellow Type is more varied than the 
 others, and is divisible into three principal sections — the Mongolian 
 proper, the Malayo-Polynesian, and the American. 
 
 The Mongolian section occupies the greater part of Asia, and 
 portions of Eastern and Northern Em'ope and ITorthern America. 
 It comprises the following races : — 
 
THE INDO-CHINESE RACE. 
 
 109 
 
 The Mongol- Altaic Race includes most of the uoinads of 
 Asia who move about, subsistiug ou their flocks aud herds, over 
 the western parts of the Asiatic phiteaus aud the plains of Western 
 and Northern Asia. They are Mohammedann, or profess a religion 
 of the Shainan'ic type (characterized by a belief in numerous spir- 
 its more or less controllable by sorcery), such as is common to many 
 miciviiized peoples. The settled branches of the race have at- 
 tained a higher degree of civilization, especially the Turks, who are 
 Mohammedans. Six-sevenths of the population of Turkey, how- 
 ever, are of other races and religions, many professing Christianity. 
 
 The Yakuts occupy a larg-e area in eastern Siberia and, thoug-h less 
 civilized than the Turks, are an iudustriou,? aud worthy people. The 
 Samoyeds dwell near the Arctic Oceau and approach the Hyperboreau 
 group, with which some have connected them. The proper classifica- 
 tion of these and many other peoples of the Yellow Type is far from 
 settled ; if divided according to their languages, as is generally at- 
 tempted, the groups become very numerous, aud the relationships diffi- 
 cult to determine. (See LansdelVs " Through Siberia.'") 
 
 Tlie Iiitlo-Cliiiiese Kace comprises the more civilized aud 
 sedentary element of the Asiatic population of the Yellow Type. 
 The typical people of this race are the Chinese. 
 
 The Chinese early attained a remarkable degree of civilization 
 far in advance of that of contemporary European nations, but 
 which suffered a singular arrest of development. They invented 
 gunpowder, the magnetic compass, and block-printing; but have 
 never brought any of these inventions to perfection. Their relig- 
 ion varies ; that of the commou people is a mi.xture of moral nui.x- 
 ims, astrology, and the worship of ancestors. 
 
 Education, so far as reading and writing are coucerned, is nearly 
 uuivei'sal, but the people ai'e a prey to the most absurd superstitious, 
 which stand in the way of any real progress. They are very industri- 
 ous, matter of fact, and economical in their habits; Chinese merchants 
 liave a world-wide reputation for shrewdness. The surplus population 
 
 the nails to grow to as great a lengtli as possible. This practice (noticed 
 by Sir Jolin Mandeville in his book of travels, 1356) also prevails among 
 the Siamese and other nations which have been more or less under the 
 control of China politically or socially in past ages. The second custom 
 is that of compressing the feet of girls, so tliat they remain undeveloped 
 and deformed tlirougb life. 
 
 Nearly related to the Chinese, long their virtual masters, are the 
 Auaniese, over whose territory the French have recently established a 
 protectorate. More distinct are the Burmese, who form with the Thibe- 
 tans a particular group. 
 
 The inhabitants of Thibet are Buddhists. They are governed by a 
 priesthood, to the chief of vvliom, called the Grand La'ma, supernatural 
 attributes are a-sci-ihed. As a people they are chiefly remarkable for the 
 fanaticism with wliich they oppose the admission of strangers to their 
 territory. They live by agi'iculture and stock-raising. (See C. R. Mark- 
 hairi's '' Mission to Tibet and Lhasa.'") 
 
 The Burmese have recently come under a Bi-itish ])rotector- 
 ate. They have a brown complexion, rather coarse features and 
 physique, and live lai-gely by agriculture, hunting, and by the 
 products of their forests and mines of precious stones. 
 
 Their government was an absolute despotism. They are Buddhists 
 by religion, aud their country contains nmnerous remarkable shrines 
 and temples. They build their houses of one story, that no one may 
 walk over their heads. Their arts and manufactures are in a poorly- 
 developed state and resemble those of India, having, probably, with their 
 alphabet, been mtroduced with Buddliism from that country (See 
 Scott^s '■'■The Burman and his Xotions.") 
 
 The Siamese are another exclusively Buddhist people, with 
 a somewhat lighter complexion and greater capacity for progress. 
 They shave the head, except a top-knot, and are among the few 
 people in the world that crop short the hair of their women. 
 Though having many customs in common with the Burmese — such 
 as regarding albino elephants as holy, and building houses of only 
 one story — they are separated from that peoj)le by language, and 
 to some extent by physical features. 
 
 Tlie customs of China, as well as of India, have left a 
 deep impression on the civilization of Siam. The ancient 
 temples in Siam and Cambodia, now liaLf concealed by the 
 jungle, have excited the wonder of travelers. The more mod- 
 ern temples, though 
 less magnificeul, are 
 still remarkable. The 
 king, in comparative- 
 ly recent times, has 
 
 among the lower classes in China is very great, so that there has 
 been an emigration into adjacent countries wherever labor is re- 
 quired; but the habits of tlie coolies (laborers) are such, that in all 
 civilized communities their existence in large numbers has been 
 found socially undesirable and injurious. In Oriental countries the 
 industry and steadiness of the Cliinese, united to his thrift, make him 
 an invaluable agent in developmg their resources. (Consult Williams's 
 " The Middle Kingdom.'') 
 
 Among the upper classes, two curious customs are noted. The high- 
 est in rank, to indicate that they do not use then- hands for labor, allow 
 
 ESQUIMAU 
 
 restricted his own (for- 
 merly despotic) power, 
 and governs with the 
 
 advice of a council of nobles. In both Burma and Siam, however, 
 nobility is not necessarily hereditary, but depends much on royal favor. 
 Slavery aud polygamy exist, and great brutality is shown in the punish 
 
110 
 
 THE HYPERBOREANS AND ESQUIMAUX. 
 
 ment of offenders. {Comijare Carl Boc¥s " Tern 
 pies and Elephants^''; and Mi^s. Leonoivens' s 
 ^'English Governess at the Siamese Court,^^ 1S70.) 
 
 The Buddhist religion, which is professed by 
 some four hundred and fifty million people of the Yellow Type, now has 
 its metropolis in Thibet, with many followers in Ceylon, Siam, Burma, ■ 
 Corea, and Japan. Formerly it was the popular religion in India and 
 jiarts of China, but has fallen into neglect there at the present tune. The 
 philosophy of this religion contains much that is admirable as moral 
 teaching, and has been welcomed by students in civilized countries on 
 that account. Its aim, to be absorbed from self-consciousness into the 
 substance of Deity, as a reward for charity and self-sacrifice — or, as the 
 Buddhist would say, " to enter Nirvana " — responds, with an idea of 
 restfulness, to the desires of the care-worn soul of man in all ages. 
 
 But, as religions are to be judged by their results. Buddhism in 
 practice must be considered a failure. Its founder, Gautama, after- 
 ward called Buddha {the Enlightened), a native of India, died of a 
 surfeit. Its priests, considering prayer a means of accumulating credit 
 with the Deity, and in proportion to the number of petitions, have as- 
 sumed that the turn of a wheel, carrying the prayer printed on paper, 
 is equivalent to offering the petition verbally. Little hand- wheels with 
 thousands of prmted prayers wound on them are commonly sold, and 
 are whirled with the left hand, while the other is employed by the 
 Buddhist in his ordinary labor. Larger prayer-mills are set going by 
 water-power, and the wheel grinds out prayers while the owner sleeps. 
 
 The priests are at once tyrants and mendicants. The hierarchy of 
 
 Thibet is all-powerful in that country, and in its forms and constitution 
 
 curiously resembles the organization of the Eurojjean chiu'ch in the 
 
 ■ Middle Ages. The purest variety of Buddhism is that now existing in 
 
 Ceylon, but it is mixed with idolatry and many gross superstitions. 
 
 The Japanese and Coreans form another group. The 
 Coreans are tributary to China, are largely Buddhists, and practice 
 Chinese methods in education and dress, ai'chitecture, and many 
 arts. Long secluded from civilization, they have lately been forced 
 to admit foreigners, and show some tendency to adopt progressive 
 methods. Physically they resemble the Chinese. {Consult Oriffiis 
 " Corea, the Hermit Nation^) 
 
 The Japanese are a small race, with brown complexion and of 
 inferior muscular development. They are remarkable among un- 
 civilized people for the facility and rapidity with which they have 
 adapted themselves to European ideas of government and educa- 
 tion. For centuries they lived almost exclusively by agriculture 
 and their fisheries ; they were governed directly by a series of 
 powerful feudal chiefs; and they scrupulously excluded all for- 
 eigners from their shoies, except at a few commercial stations. In 
 
 '■'J 
 
 1 mHt|| 
 
 Wf^- 
 
 w 
 
 " t 
 
 HU 
 
 LLCHt 
 
 
 a few 3'ears all this has been 
 changed. The Japanese have 
 estabhshed a government on 
 modern principles, entered in- 
 to diplomatic relations with 
 European and American na- 
 tions, opened institutions of learning, and engaged in an exten- 
 sive commerce. 
 
 A very prominent characteristic of the Japanese people is their re- 
 fined taste in decorative art and its application to objects of daily use, 
 especially those of pottery and porcelain, or those wrought in wood or 
 bi'onze. This art is supposed to have originated in Corea ; its develop- 
 ment in Japan has been the marvel of artists the world over. {See 
 Morse's ^'Jaj}anese Homes and their Surroundings.") 
 
 The Hyperho'reans (beyond Boreas, the north-wind), so 
 called because they live in the northern part of Siberia, form a 
 group rather than a race. Many of the tribes constituting this 
 group are nearly extinct. They are mostly nomads, living on their 
 herds of tame reindeer, like the Samoyeds and Lapps. {See Kelt- 
 nan's "Tent-Life in Siberia.'''') 
 
 The most important people of the group are the Kariaks of the ex- 
 treme northeast of Siberia and Kamchatka. A section of this peo- 
 ple, called Chuk-chi, have attracted some attention because, being con- 
 founded with certain tribes of Esquimaux settled among them, they were 
 supposed to form the connecting link between the native races of Asia 
 and America. This is now known to be an error. 
 
 The Esqniniaux are a remarkably unifoi-m race, of Mon- 
 golian physique. They live on the Arctic shores of America, Asia, 
 and the archipelago north of America, of which Greenland forms 
 a part. {See Crantz and Egede''s '■^Greenland.") 
 
 The Esquimaux have mastered the means of existence amid ice and 
 snow, by methods which show extraordinary ingenuity. A few small 
 bands have been driven across Bering Strait, at a comparatively re- 
 cent date ; others extend southward on the shores of Alaska nearly to 
 Mount St. Elias. Across the whole northern border of America to 
 Greenland, they show an extraordinary uniformity of language, arts, 
 and mode of life. The stunted mixed tribes of Danish Greenland have 
 usually been taken as the type of the race ; but the Esquimaux of North- 
 west America show a much fijier physical development, as do also the 
 recently discovered wild tribes of East Greenland. The natives of the 
 
THE AMERICAN INDIANS. 
 
 Ill 
 
 Aleutian Islands, tliougli now Christianized and civilized, are a branch 
 of the Esquimau race modilied niore than any of the others by the isola- 
 tion aud peculiar conditions of their island homes. {Consult Rinlc's 
 "Tales and Traditions of the Esquimaux^' ; and Dall, "Contributions 
 to North American Ethnologij,^' vol. i.,pp. 93-lOG.) 
 
 Some peoples of Northern Europe, the Lapps and Finns, belong 
 [ihysically to the Yellow Type, and are generally associated with the 
 Mongol-Altaic race, though their language aud habits have been much 
 modified by contact with other races. (See TronihoWs " Under the 
 Rai/s of the Aurora Borealis," vol. i.) The Magyars (mod'jors) of 
 Austi'ia-Hungary are a ])eople of Mongolian origin, and the only branch 
 of that race which has attained to the spirit of modern civilization. 
 
 The Malayo-Polynesiim Section of tlie Yellow Type 
 of man comprises the brown people of the Pacific islands, Hawaii, 
 Tahiti, and many others, the Maories of New Zealand, and the 
 Malays of Sontheastern Asia. {Compare Captain. James Coolc, 
 " Voyages to the South Seas"; Hochstetter" s '•'■New Zealand^) 
 
 These people display the highest type of physical beauty among the 
 yellow races. The original stock is supposed to be best represented by 
 the inhabitauts of the Hawaiian islands and the Marquesas. The Malay 
 tribes had occasionally risen, as in Java, to a superior degree of civiliza- 
 tion before feeling the influence of Europeans, but the Malay stock is 
 believed to contain a mixture of several races. At the pi'esent day, the 
 Ho'vas of Madaga.scar and the Hawaiians have adopted more or less 
 comi)lctely the manners and religion of civilization; and other Poly- 
 nesians are following in their steps. The Malays, on the other hand, 
 have degenerated rather than improved. {See Forhes's " Naturalisfs 
 WawJerings in the Eastern Archipelago.'''') . 
 
 epithet " Red," so often applied to the Indian, is, in general, sin- 
 gularly inaccurate. It arose from the fact that the (Jaribs, a race 
 inhal)iting the Antilles at the time of their di.scovery by Columbus, 
 had a ruddy complexion, which they heightened by the use of red 
 (X'hre. From them, tlie misnomer of '' Ked-skin " was extended to 
 the people of North America in general. {See Nadailldo's '^Pre- 
 historic America") 
 
 At the time of the discovery of America, the natives differed in the 
 development of their social system, in arts, language, aud mode of life. 
 Among all the tribes, one featui'e was characteristic — the welfare of the 
 community was the chief object of duty — comparatively little was left 
 to the will or jjreference of the individual, and the complexity of these 
 social restrictions increased with the ei\nlization of the tribe or people. 
 The common notion of the enjoyment of a free and untrarameled ex- 
 istence by the wild Indian is wholly' false. There were, perhaps, no 
 peo])le in the world so bound by a nmltitude of ciustoms, which were 
 enforced more vigorously than most written laws of civilized lands. 
 The exact mode of cutting his hair, the place where he nuist sit in the 
 lodge or hut, the very phrases he must use in addressing his relatives or 
 associates, were all i-igidly fixed. {Consult Morgan, "Contributions to 
 North American Ethnology," vol. ir.) 
 
 The Indians are now known to belong to a great number ot 
 groups, characterized by differences of language ; l)ut they may be 
 conveniently classified according to their mode of life. The least 
 elevated tribes were more or less nomadic, with no permanent 
 houses or villages. In the East they Hved in tents or lodges, during 
 the fishing-season by the rivers or sea, during the hunting-season 
 
 The American In- 
 dians are the last section 
 of the Yellow Type to bo considered. The aboriginal peoples of 
 the two Americas, from Patagonia to the Arctic regions, have many 
 features in common. The general structure of their languages is 
 similar, in sjute of wonderful diversity of detail. The stage of 
 progress from barbarism which most of them had reached at the 
 time of (\)lumbus, was, with certain exceptions, much the same. 
 Even the so-called civilization of the ancient Mexicans and Peru- 
 vians, nnich misunderstood, and consequently misrej)resented by 
 early historians, as well as by some modern writers, was of a nature 
 entirely compatible with development from the state of which the 
 average Indian was then a type. 
 
 The American race is characterized by long, black, straight 
 hair, black eyes, large and generally coarse features, high cheek- 
 bones, a prominent but not large nose, and a complexion varying 
 from ruddy to pale olive through various shades of brown. The 
 
 in the mountains or on the edge of the forest. In the West, up to 
 a recent period, such tribes followed the migrations of the buffalo 
 and other large game. They could easily retreat before the whites, 
 aiul often may have saved themselves when the more settled aud 
 civilized tribes stood by their homes until lioth were destroyed. 
 
 Monnd-Biiiklers.— In tho.se regions where the climate made 
 it easier to obtain a living by regular labor, settled villages, de- 
 fended by fortifications, existed, and agriculture formed an impor- 
 tant ]nirsuit. Large quantities of corn and pumpkins were gro\vn ; 
 mounds of earth were erected for defense, as sites for altars or 
 temples, over the bodies of distinguished chiefs and warriors, and 
 as common grounds for games or athletic exercises ; pei'haps, for 
 other purposes, also. Such mounds were constnicted and in use 
 by the Natchez and other Southern tribes at the time of their dis- 
 covery. {See Lucien Carres '■'■Mounds of the Mississippi Valley") 
 
 Mounds, apparently erected for similar purposes, are found 
 from the mouth of the Mississippi northward to Hudson Bay, and 
 
112 
 
 THE WHITE TYPE. 
 
 are especially remarkable in the Ohio Valley. It is supposed by 
 the most receut investigators that the peoples or tribes who con- 
 structed these works, and who are popularly styled " Mound-build- 
 ers," were not dissimilar to the known mound-building tribes (such 
 as the Iroquois, Creeks, and Natchez). It is thought that they were 
 dispersed or destroyed by war or pestilence, and that their territory 
 was subsequently occupied by nomadic or less advanced nations. 
 {See Squier, '■^Smithsonian Contributions,^'' vol. ii., jp. 83.) 
 
 Cliff-Dwellers. — In the Southwest, the absence of timber 
 resulted in the use ot stone or sun-dried brick, as a material for 
 building, by the settled tribes. The large tribal structures, cui-i- 
 ously arranged for defense, were called by the Spaniards pueblos 
 (villages). For retreat in case of need, some of the natives built 
 on ledges in front of cliffs, or on isolated rocks, almost inaccessible 
 houses whicli have received the name of " Cliff-dwellings." Certain 
 of these were inhabited for long periods ; but most of them, prob- 
 ably, served only as places of refuge ; and some have been found 
 which, though carefully finished, seem never to have been occupied. 
 
 Aztecs and Peruvians. — In the fertile plateau of Mexico 
 and in the highlands of Peru and Bohvia, the highest American 
 civilization was reached. Here, though the use of ii'ou was un- 
 known, large temples and stone cities were built, roads made, 
 aqueducts constructed ; and the arts of weaving, gold and copper 
 working, carving, and sculpture, attained a remarkable degree of 
 progress. The worship of the sun and moon, the deification of dead 
 heroes, and even human sacrifices on a grand scale, were prominent 
 featm'es of the rehgious system. A complicated calendar and some 
 rude attempts at partly phonetic hieroglyphic writing were foimd 
 by the Spaniards in Mexico. (See HabeVs ^'■Central American 
 Investigations,^'' '■^Smithsonian Contributions,'''' vol. xxii.) 
 
 At present, the ancient civilization is known only by the ruins of its 
 temples, and from early Spanish records. Pueblos, as at Zuni, are stUl 
 inhabited, protected by the desert, but the Indians of the Mississippi and 
 Ohio Valleys and the Atlantic slope, know their old homes no more. 
 
 Remnants of some tribes are now settled in the Indian Territory re- 
 served for tlieir use hy the Government, and are more or less civilized 
 and prosperous. Nearly all the Indians of the United States are now 
 on government reservations ; while in South and Central America and 
 Mexico, though diminished in numbers, many thousands of the wild 
 tribes still continue in nearly their original mode of life. 
 
 Of existing Amei'ican peoples the Tupi and Guarani tribes, widely 
 spread in Brazil, the Mayoruna of eastern Peru, the Tehuelches and 
 Araucanians of southern South America, may be cited. In North 
 America are the Algon quins, of whom the Arapahoes are a tribe ; the 
 Athabascans, to which group the Apaches belong ; the Sioux, widely 
 spread northwest of the Mississippi ; and the Zuiiis, one of the tribes still 
 dwelling in pueblos. Of a strongly marked group found on the shores 
 of northwest America, the Haida and Tlinkit peoples are among the 
 most noteworthy. They are a laborious and settled race, remarkable for 
 their proficiency in carving and for their independent manners. [See 
 DalVs ^^ Alaska and its Resources,^'' part ii., chapter Hi. ; G. M. Daiv- 
 son^s "On the Haida of Queen Charlotte Islands.''') 
 
 Questions. — What are the characters of the Yellow Type ? Into what sec- 
 tions is it divided ? Name the races of the Mongolian section. Enu- 
 merate the chief peoples of the Mongol-Altaic race ; of the Indo-Chinese 
 race ; of the H3'perborean group. Characterize the Chinese ; the Bur- 
 mese ; the Siamese. What contrast exists between the theory and prac- 
 tice of Buddhism ? Describe the Coreans ; the Japanese. For what are 
 they particularly remarkable ? 
 
 Who are the Hyperboreans ? What people of this group is the most note- 
 worthy, and why ? Characterize the Esquimaux. How are they distrib- 
 uted ? What is the physical difference between tnb Danish Esquimaux 
 and the uncivilized tribes ? What other people, now civilized, form a 
 branch, of the Esquimau stock ? What Euiopean peoples are of Mongohan 
 
 origin ? Whicli of them has become entirely civilized and progressive ? 
 Of what peoples is the Malayo-Polynesian section composed ? What are 
 their relations to civilization ? 
 By what social and physical characters are the original inhabitants of America 
 connected ? Why have they been called Red Indians ? How did they 
 differ at the time of the discovery of America ? What common feature 
 was characteristic of their social life ? What distinctions in their mode 
 of life enable us to classify the American tribes ? Who and what were 
 the Mound-buUders ? the Pueblo people ? What relation to the pueblo 
 settlements had the cliff-dwellings ? Where was the highest type of 
 American culture reached ? What were its chief features ? State the 
 present condition of the American tribes in North and South America. 
 
 THi: WHITE TYPE. 
 
 The White Type of mankind is that with which we are 
 most familial', and of which the enlightened and progressive na- 
 tions of the world are chiefly composed. It is characterized by a 
 prominent nose, with medium or non-projecting jaws, and straight 
 or curly hair, abundant on the face and person ; the average ca- 
 pacity of the brain is greater than in the other types. The White 
 Type is divided into two sections, the Blondes and Brunettes, or 
 light and dark races. Some of the latter are very dark, but are 
 separated by the nature of the hair and other characteristics from 
 races of the black type. 
 
 The Blonde races include the Teutonic, Caucasic, Afghan, and 
 Berber stocks ; the Brunette races are the Latin or Bomanic, the 
 Semitic, the Hamitic, most of the Asiatic Aryans, the Maiotze of 
 China, and the Ainos of northeastern Asia and Japan. 
 
 The Teutonic or Indo-Gernianic Race contributes the 
 majority of the people making up the nations of England and her 
 colonies, the United States, Germany, the Scandinavian kingdoms, 
 Holland, and, to a less extent, Russia. 
 
 The Teutonic peoples passed through many changes and migrations 
 before the era of civilization. The contrast between the Celts (Irish, 
 Welsh, Highlanders) of Britain and the typical Englisli is in lai'ge part 
 a contrast between the descendants of historically early and later emi- 
 grants from the European Continent, both offshoots from a still earlier 
 exodus of Aryan peoples from the Asian plateaus. 
 
 The Caucasic Race includes the Circassians and Georgians, with 
 other people living on or near the mountains of the Caucasus, between 
 the Black and Caspian Seas. The people of the Caucasus gave their 
 name to the White Type, so generally called Caucasian, because the 
 earlier writers on the subject supposed them to be physically the finest 
 modern examples of the type existing in an unmixed state. Later trav- 
 elers believe the reputation undeserved, or much exaggerated. 
 
 The Afghan Race occupies the mountain-region between Russian ^ 
 Turkestan on one side, and Persia and India on the other. This race is { 
 mixed, and the name Afghan includes many brunettes, partly at least of 
 Semitic origin. 
 
 The Berber Race is a blonde people of North Africa, especially 
 of Morocco and Algeria, whose mode of life is much the same as that of 
 the surrounding darker races. 
 
 The Romanic Race includes the dark people of southern 
 Europe — the Italians, French, Spanish, Portuguese, Greeks, etc. 
 
 They derive their name from the fact that their languages are most- 
 ly related to the Latin, spoken by the ancient Romans. They are chiefly 
 derived from emigrants of Aryan extraction, known as Pelasgians. 
 
 The Semitic Race includes the Arabs, the Aramaic or 
 Syrian peoples, and many of the Oriental Israelites. The Moors 
 of Morocco, the Himyarites, and others in Abyssinia and north- 
 eastern Africa, though mixed, have a large share of Semitic blood. 
 
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114 
 
 THE WHITE TYPE. 
 
 Among ancient nations, the Semitic race 
 was pre-eminent in spiritual gifts, intelligence, 
 and' in commerce and mantiine enterprise 
 Through a Semitic people, the Hebrews, ■we 
 have received the Bible and the Ohiistian re- 
 ligion ; from another, the Phoenicians, oui al- 
 phabet ; the Arabic numerals, the elements of 
 chemistry, physics, medicine, 
 and astronomy, were, in the 
 form in which they have "'^i. \ 0f/^J^' 
 
 
 The Maiotze, of southeastern China, 
 and tlie Aiiios, of Japan and the Kiirile 
 Islands, aie geneia]l_) admitted to he of the 
 White Type. They aie as yet imperfectly 
 known, and thtii ultimate relations to other 
 
 laees ot that ajroiip are yet to 
 
 be investigated. 
 
 The Maiotze are definitely known 
 -''' not to be Mongolians. The 
 
 come to us, the products of Arab learn- 
 ing and ingenuity. The Mohammedan re 
 ligion, next to the Christian the most pow- 
 erful in its influence on mankind, is of Se- 
 mitic origin. Among the extinct Semitic 
 peoples are the Assyrians, Carthaginians, 
 Phcenicians, and Canaanites. {See Lad;/ 
 Duff Gordon's ''Last Letters from Egypt.''') 
 
 The Haiiiitic Race includes the 
 
 Egji^tians, Libyans, and Numidians, or 
 Ethiopians. 
 
 Of this race are the Copts, the Ealayles 
 of North Africa, and the Somali and Galla 
 people of the region about Abyssinia. To 
 it also belonged the ancient Egyptians. Its 
 actual representatives are of very mixed 
 blood, and contain the darkest examples of 
 the White Type of man. 
 
 The Asiatic Aryans comprise 
 the Hindoos, the Persians, the people 
 of Kafiristan sometimes called Galehas, 
 
 the Armenians, Baluchees, Kurds, and 
 Parsees. 
 
 The origin and migrations of the Aryan 
 stock, from which so many races and pow- 
 erful nations have sprung, are still subjects 
 of controversy. It is generally conceded 
 that the original home of the Ai'yans was 
 in central Asia ; that they spoke a language 
 most nearly related to the Sanskrit of India ; 
 and that they were a pastoral people. From 
 the cradle of their race, in prehistoric times, 
 great bodies successively migrated in differ- 
 ent directions, ultimately making jiermanent 
 settlements in Persia, northern India, and va- 
 rious parts of the European Continent. These 
 emigrants were the progenitore of the Aryan 
 and Teutonic nations. (See Professor Max 
 Miiller's article entitled ''Aryan" Eney- 
 cloprrdia Britannica, vol. ii., p. 672.) 
 
 ^1RC/\SS\^^ 
 
 Ainos were apparently the original in- 
 habitants of Japan, before the advent of 
 the Japanese. They are noted for their 
 profuse growth of hair, and their mild 
 and amiable manners. They are in a 
 very low state of culture. (Consvlt 
 Miss Bird's "Unbeaten Tracks in Ja- 
 pan.") 
 
 ftuestions. — What are the cbaraoteris- 
 tics of tlie White Type ? Into what sec- 
 tions is it divided ? Why is it difficult 
 to classify civilized peoples ? Name the - 
 Blonde races ; the Brunette races. What 
 nations are chiefly formed by members of 
 the Teutonic race ? To what is due llie 
 contrast between the British and Irish Celts 
 on the one hand, and the typical English- 
 man on the other ? Of what people is the 
 Caucasic race composed ? How did the 
 n imp of this small nation become applied to all peo- 
 ple ot the White Type ? 
 
 Who compose the Afghan race, and wliat other 
 race has mixed with it ? What region does it oc- 
 cupy ( Describe the Berber race ; the Romanic race. 
 Why are the latter so called, and from what people 
 aie thev supposed to have sprung? What modern 
 pLOplpv are Romanic ? What people are included in 
 the Semitic race ? How has this race been distin- 
 guished ? What essentials does modern civilization 
 ov. e to people of this race ? AVhat great religions 
 have been received through Semitic peoples ? What 
 remarkable peoples of antiquity, now extinct, were 
 StmitLs? (On the Semitic f.amily of languages, an- 
 cient ind modern, and tlie distribution of the Semites 
 m antiquity, consult Quackenbos's "History of Ancient 
 Liteiature," pp. 17, S5, IO4, 114.) Enumerate the 
 peoples of the Hamitic race ; the Asiatic Aryans. 
 What IS supposed to have been the history of the 
 Aivin stock ? What people of China and Japan are 
 supposed to be of the White Type ? Define the gen- 
 tial nitureofthe differences that exist between the 
 principal races of men. 
 
MINERAL PRODUCTS AND THEIR DISTRIBUTION. 
 
 I 
 
 Economic Geology. — In the opening chapter of this work, 
 on the Structure of tlie Earth, was presented an interesting scien- 
 titic consideration of the subject of geology in connection with its 
 relations to Physical Geography. The science of geology, how- 
 ever, is also of singular practical value to civilized man, in that it 
 teaches him how and where to tind in the several classes of rocks 
 those mineral jjroducts so essential to his welfare — the materials 
 used in the construction, adornment, lighting, and heating, of his 
 dwellings and factories ; in the manufacture of his tools and ma- 
 chinery ; in the enrichment of exhausted soils; the substances em- 
 jiloyed in the vai'ious arts ; the pigments and dyes ; the mineral 
 medicines ; the precious metals, and the gems. 
 
 Geology furnishes, moreover, the necessary data for the valua- 
 tion of land as regards its agricultural and mineral resom-ces ; de- 
 termines the feasibility of proposed road, railway, and canal con- 
 struction, and of river improvement ; and delines the prospective 
 profit in newly opened mines and quarries. {Head Profenwr 
 Paijc'x ^PJconomlc Gcoloijy.'''') 
 
 Man can make little progress in civilization without availing biitiself 
 of the mineral and metallic stores hidden in the earth's crust. The earli- 
 est records of the human race represent the most enlightened communi- 
 ties as familiar with metallurgy ; while those who fashioned then- uten- 
 sils and weapons out of stoue lived in a state of general savagery. The 
 presence of useful and precious minerals has had much to do with the set- 
 tlement of important regions, and the development of agricultural and 
 manufacturing industries. (See Professor Joly's ''Man before Metals.'') 
 
 Forms of Minerals. — Mineral bodies occur in a solid, 
 liquid, and gaseous form. While few are now met with in a state 
 other than solid, there is reason to believe that many of oxir famil- 
 iar minerals once existed as gases or liquids, and that their present 
 structure was determined in the process of solidification. 
 
 Bodies that have thus resulted are divided by mineralogists 
 into two classes : I. Amorphous {without a form), having no regu- 
 lar figure, breaking with equal facility in all directions, equally 
 hard and elastic throughout; for example, common iron- ore. II. 
 Crystalline, having a definite geometrical form bounded by plane 
 surfaces symmetrically arranged, more easily separable and con- 
 ducting heat more rapidly in certain directions, as a rule not 
 equally hard and elastic throughout ; for example, the diamond. 
 The same mineral body sometimes occurs both in a crystalline and 
 amorphous condition, as gold. {Consult Professor EglestovUs '■'■Lect- 
 ures on Crystalloijraplujr) 
 
 The Geographical Distribution of Minerals, unlike 
 that of plants and animals, does not depend on climate or elevation 
 above sea-level. Mineral bodies are not confined to particular sec- 
 tions of the globe. Some occur near the surface in alluvial soil or 
 the sandy beds of rivers ; others lie deeply imbedded in the earth's 
 crust, and are obtained only with great expense and labor. Many 
 of the most important deposits are found in mountainous regions. 
 
 METALS AMD METALLIC ORES. 
 
 Classification of Metals. — Among the subjects of eco- 
 nomic geology, that of metallic substances possesses singular in- 
 terest and value. To metals, man owes his ascendency over Na- 
 ture : restricted to wood, bone, and stone, he must have remained a 
 savage. {Compare Dr. Ahhott's ^'Primitive I)/Justri/, or lllastra- 
 tions of Handiwork in Stone, Bone, and Clay."") 
 
 The most important metals are gold, silver, plat'inum, mercury, 
 iron, lead, copper, tin, zinc, nickel, and antimony. The first two 
 are called Precious Metals. They occur chietiy in a native state, 
 but alloyed to some extent with each other. Platinum is also met 
 with native ; the others are generally found as ores — that is, in 
 chemical union with other substances. The total value of the min- 
 eral proiluction of the United States in 1896 was $74<i,7t!8,(M)0. 
 
 Gold, the most valuable of the metals, has been prized fi'uni 
 the earliest ages. Gold jewelry and vessels are found in Egyptian 
 tombs (visit the Al>bott collection in the library building of the 
 New York Historical Society), and ancient Etruscan artists worked 
 the metals into exquisite ornaments. A knowledge of the metal- 
 lurgy of gold at less remote periods was wide-sj)read. 
 
 Gold occurs in nature chiefly in the metallic state — frequently iu 
 octahedral crystals, more conmionly in irregidar masses called "nug- 
 gets," from a few gi-ains to many pounds iu weight, or in the form of 
 dust and "scales." Its color is yellow of some shade; it retains its 
 luster in the air, and its solid form in a temperature below 2,000° ; it is 
 from sixteen to nineteen and a half times as heavy as pure water. Gold 
 is extremely malleable and ductile ; it may be beaten into leaves only 
 sWairff of au inch iu thickness; a single grain of it cau be drawn into a 
 wire five hundred feet long. The test for gold is its I'csistance to com- 
 mon reagents; it is soluble iu nitro-muriatic acid (aqua regia). Native 
 gold is soft; when alloyed with copper which heightens its tint, or with 
 silver which lowers it, the metal becomes sutliciently hard to be coined 
 into money or manufactured into ornaments. (See EglestoiCs ''Metal- 
 lurgy of Gold, Silver, and Mercury in the United States.'') 
 
 Gold is widely, though sparingly, distributed over the earth, occur- 
 ring in veins of quartz, or scattered in stream-drifts of sand and gravel. 
 
 In quartz-mining, the rock is got out, sometimes from considerable 
 depths, and reduced to powder by macliinery, so as to detach every 
 particle of metal. The quartz is tlien washed away with water, quick- 
 silver being used to combine the fine metallic particles with itself in an 
 "amalgam," from which the gold is afterward separated. When gold 
 occurs in deposits of gravel, which from the surface down may be as 
 thick as 500 feet, it is obtained by hydraulic mining. 
 
 The Richest Gold-Fields in the world lie in the region 
 between the Pacific Ocean and the Great Plains of North America. 
 Since the discovery of gold in California, in 1848, the total yield 
 of the United States has been not far from $2,000,000,000 ; in 1896, 
 the value of the ]n-oduct was $.52,886,200. Mexico and Central 
 America also contain valuable gold deposits ; while in the Yukon 
 districts of Alaska and of the adjoining territory of the Dominion 
 of Canada are some of the richest mining areas at present known. 
 There are gold-bearing localities also on the Atlantic slopes of 
 North America, and rich gold- veins in Brazil, Guiana, and among 
 the Andes. 
 
 The Australian gold districts, which have been ranked next to Cali- 
 fornia in importance, cover an extensive area. New Zealand and Japan 
 as well contain large deposits. Valuable deposits have recently been 
 discovered in Tasmania. The amount of gold pi'oduced iu Continental 
 Europe, principally in Austria-Huugary, is estimated at about $5,000,000 
 a year ; while the mines on the eastern slopes of the Ural Mountains 
 have long been richly productive. Native washers still obtain small 
 quantities of the precious metal in the highlands of India. 
 
 In Africa, formerly, the principal gold-bearing regions were on the 
 west coast-— the English piece called the guiuea was so called because 
 originally coined from gold exported from the Guiuea ti'ading-stations. 
 But, more recently, alluvial deposits have been worked in the mountains 
 of the Transvaal; and the discovery, in 1886, of gold-bearing "reefs" 
 of great richness has attracted thousands of miners to these South Afri- 
 can gold-fields. Since then they have proved among the most valuable 
 in the world. 
 
116 
 
 IMPORTANT METALS. 
 
 The value of gold at present in circulation among the great com- 
 mercial nations has heen estimated at about $4,000,000,000. 
 
 * Silver is much more abundantly distributed than gold. It is 
 rarely found native in " strings," " plates," and " nuggets," but 
 usually occurs as an alloy in combination with gold, lead, mer- 
 cury, copper, or sulphur. It is both malleable and ductile. 
 
 Like gold, silver has been used from early ages for coinage and the 
 manufacture of ornaments and household utensils. The most produc- 
 tive mines have been those of Mexico; but while their yield has of late 
 diminished, that of our own mines has largely increased, and the region 
 between the Rocky Mountains and the Sierra Nevada has now taken the 
 foremost rank in the production of this precious metal. The silver- 
 bearing mines of Colorado are the largest producers. The amount of 
 silver produced in the United States in 1896 was over 58,000,000 fine 
 ounces. South America contains silver deposits of great value ; while 
 the Spanish mines are the most productive in Europe. 
 
 The value of silver at present in circulation throughout the civilized 
 world is estimated at more than twice that of gold. The value of silver 
 relatively to that of gold is subject to constant change. The ratio of 
 silver to gold increased from 14.94 in 1687, to 31.60 in 1895. 
 
 Platinum (from a Spanish word j>?a<i'?i«, meaning little sil- 
 ver) was discovered to be a distinct " noble metal " about the mid- 
 dle of the last century. It occurs only in a metallic state, is one 
 of the heaviest of metals, and from its wonderful resistance to 
 heat is used almost exclusively for chemical utensils — crucibles, 
 evaporating dishes, and stills. 
 
 The Russian government for a time stnick platinum coins, but dis- 
 continued the practice on account of the fluctuations in the value of the 
 metal. About three tons are annually j)roduced, most of it on the east- 
 ern slopes of the Ural Mountains. This valuable metal is also found in 
 some of the gold-washings of California and of the South American 
 mines and in Australia. 
 
 Mercury, of brilliant white color, and distinguished from all 
 other metals as the only one that is liquid at ordinary tempera- 
 tures, is also known as quick (or living) silver. At 37.9° below 
 zero Fahr., it freezes ; at 675° F., it boils and is vaporized. 
 
 Mei'cury occurs sometimes pure, in the form of globules, generally 
 as a red sulphide called cinnabar. Of European mines, those of Alma- 
 den (ahnah'den) in Spain and Idria in Austria, with those of Italy and 
 Russia, furnish most of the mercury of commerce. The first are now 
 almost equaled by those of New Almaden in California. 
 
 Mercury is used in the construction of thermometers, barometers, 
 and other philosophical instruments. Its affinity for gold and silver 
 makes it valuable in the process of extracting these metals from quartz, 
 as already indicated. Two chlorides are used in medicine — calomel and 
 corrosive sublimate. Blue-pill (mercury rubbed up with confection of 
 roses) and mercury with chalk have long been popular remedies. 
 
 Iron, the most useful metal, is also the most abundantly and 
 widely disseminated. In a pure state, it is characterized by luster 
 and hardness, and when broken across exliibits a ragged fracture. 
 Great heat is required to melt it. "When white-hot it becomes 
 soft, and can be forged into any shape, which it retains when 
 cooled. Two white-hot masses of iron admit of being welded — 
 i. e., pressed or heated together iato one. 
 
 Iron is characterized by great strength and tenacity ; it is both duc- 
 tile and malleable, as well as elastic. Hence its use from early ages in 
 the manufacture of cutting-instruments, both weapons and tools, and its 
 intimate connection -with the progress of civilization. 
 
 Iron-ore is abundant in different parts of the United States and Eu- 
 rope. Great Britain stands first, araong European countries, in the 
 manufacture of iron. Swedish iron has a high reputation. 
 
 Iron is used in three forms : 
 
 Cast-iron, made directly from the ore, contains from 2. 5 to 5 per 
 cent, of carbon, and is capable of taking the minutest forms from the 
 mold. It is the cheapest variety, and is used for a thousand purposes. 
 
 Wrought-iron contains from .2 to .5 per cent, of carbon, and is made 
 from cast-iron by diminishing the proportion of this element. It pos- 
 sesses great tenacity, and can be rolled into plates or sheets as thin as 
 paper. Nails, wire, etc., are made of wrought iron. 
 
 Steel is iron combined with from J to 1\ per cent, of carbon. It is 
 harder, whiter, and more elastic, than either cast or wrought iron, and 
 takes a higher polish. It may be tempered to different degrees of hard- 
 ness, and is employed for making the rails for railroads, plates for iron- 
 clads, and other countless objects. 
 
 Irou has been used in the treatment of diseases from an early period. 
 It promotes the reproduction of blood-corpuscles in the disease known 
 as anaemia, characterized by pallor and general depression. Mineral 
 waters containing iron are also popular blood-tonics. 
 
 Copper. — Next in usefuhiess to iron stands copper, so called 
 from the Island of Cypress, whence the Romans derived their 
 principal supplj'. It has been used from prehistoric times in the 
 form of an alloy called bronze. Archaeologists have given the 
 name of Bronze to a remote age in which this metal was exten- 
 sively employed in the manufacture of arms, ornaments, etc. 
 
 Copper is of a brilliant-red color ; it is both malleable and ductile, 
 and tenacious like h-on. It occurs m numerous ores, as well as in a 
 native state. Malachite, a green carbonate, is a beautiful and valuable 
 ore. The sulphate, hlue-stmie, is used in the arts. 
 
 The richest copper-mines in the world are in Montana, and on the 
 shores of Lake Superior, in Northern Michigan, where blocks of native 
 metal weighing two hundred and fifty tons have been found ; pieces of 
 from ten to fifty tons are not uncommon. Chile produces large quan- 
 tities of this metal; while the most productive copper region of Europe 
 is Spain, whose mines were worked by the Romans. 
 
 Lead, a soft, bluish-gray metal, easily manipulated, is invalu- 
 able in the arts. It was known to the ancients, and used by the 
 Romans, as with us, for the manufacture of water-pipes. Com- 
 bined with other metals, it produces valuable alloys, like pewter, 
 solder, and type-metal. 
 
 The chief lead-producing countries are the United States, England, 
 and Spain. Most of the silver mined is found in combination with lead, 
 the ores of which are melted on a large scale in the West for the purpose 
 of obtaining this precious metal. 
 
 Tin is a soft, silvery-white, highly lustrous, and very malleable 
 metal, a good conductor of heat and electricity, and not easily 
 affected by moisture ; hence its value for the manufacture of do- 
 mestic utensils. It is largely employed for coating other metals. 
 The oldest tin-mines are those of Cornwall in England, which have 
 been worked from ancient times ; the richest are those of Tasma- 
 nia, the Malay Archipelago, and Bolivia. 
 
 Zinc is a soft metal with bluish-gray tint, harder than tin, and 
 extremely malleable when heated so that it can be rolled into plates. 
 Sheets of zinc are largely employed for roofing, and lining surfaces 
 that come in contact with water, as this metal displays a peculiar 
 resistance to oxidation. Therefore it is used for coating iron, which, 
 when thus protected from rusting, is known as galvanized iron. 
 Zinc is mined in Europe, in Northern Africa, and the United States. 
 
 Nickel is a brilliant metal whose value is derived from the 
 fact that it combines in itself the characteristics of iron with some 
 of those of the precious metals. As it does not tarnish by long 
 exposure to the air, it is extensively employed in electroplating. 
 German silver is an alloy of nickel, copper, and zinc. 
 
 Nickel is found in Pennsylvania, Oregon, and Nevada; in parts of 
 Europe, and in New Caledonia. The mines of the Sudbury district in 
 Canada furnish the greater part of all the nickel produced in the world. 
 (The student is referred to Professor Egleston's '■'Lectures on Mineral- 
 ogy,'''' and Professor Dana's "System of Mineralogy") 
 
iJUlI.niNG-STONES AND OTIlKlt MINERAL PltODUCTS. 
 
 ii7 
 
 BUILDIJ^G-STOJ^ES, FUELS, ETC. 
 
 TJu' LiiiU'stoiies constitute an extreiuclv nsrfnl gronp, wide- 
 ly distriliuted over the eartli. Tliey are of close irrain, and hard 
 enough to ))e cut into blocks. When tndy crystalline, they are 
 known as iiuirhles, and are susceptible of a liigh polish. They 
 vary in color fi'oni a ijrayisli or neutral tint to the exquisite waxy 
 white of the statuary marbles. 
 
 Quarries are worked in different parts of the United States; the 
 marbles of Vermont h;ive a Iiig-h rei)utatioii for beauty. The finest 
 stone for statuary purposes comes from Carrara ikar-rali'raJi), Italy. 
 
 Limestones ai-e absorbers of water, and lienee, when subjected to 
 sudden changes of weather, are apt to become rotten and disintegrate. 
 Stones near the top of a quarry are often cracked and broken, while 
 those taken from greater depths ai-e perfect. 
 
 Granite is a mass of Hesh-eolored crystals of felds])ar, and 
 bright flaky crystals of mica, imbedded in (juartz {see j)- 10). As a 
 building-stone, it is nearly imperisbaijle. Granitic rocks are char- 
 acterized by niggedness. (On the limestones and marbles, .«'^ 
 Anst,',r.<< ''The Great Stone-Bool of Nature," p. 70.) 
 
 Sandstones are composed of particles of sand or pebbles in 
 some way adherent or cemented togethei'. When the pebbles in 
 the mass are of conspicuous size, it is called pudding-stone. The 
 colors vary according to the composition. Some sandstones are 
 exceedingly durable; others, like the brown-stone so much used 
 for the fronts of Iniildings, easily decay and splinter. 
 
 The Clays and Chalks. — Clay is a chemical combination 
 of a nnueral called alumina with silica. In an absobitel}- piire 
 state it is seldom met with in nature, being always combined with 
 water, and generally mixed with sand and other impurities. A 
 characteristic property of clay is its plastic nature, wliich renders 
 it callable of l)eing fashioned into any shape when moistened ; if 
 then exposed to great heat, it is deprived of the water without los- 
 ing its form, and remains permanently hard. Thus clay is manu- 
 factured into bricks, tiles, drain-pipes, pottery, etc. 
 
 From superior varieties of brick-clay, terra - cotta work is made. 
 China-clay, from which porcelain is manufactured, is a still finer variety. 
 Originally obtained from Cidna, it is still known by its native name of 
 kaolin. Beds of kaolin have been discovered in the United States. Ful- 
 ler's earth, another clay so called because formerly used in fulling or 
 cleaning cloth, possesses the property of readily absorbing grease. Fire- 
 clay is used in making crucibles for melting glass and the metals. Clay 
 tliat has been subjected to enormous pressure is known as slate, and has 
 a variety of practical applications. 
 
 Chalk is almost absolutely pure carbonate of lime. Examined 
 under the microscope, it is found to consist of minute shells, " thou- 
 sands of which would be required to bury a pin's-head." 
 
 Chalk has a marked atfiinty for water ; a cidjic foot of it will absorb 
 two gallons, or nearly one-third of its own volume. Its chief use is in 
 the manufacture of lime for mortar or fertilizing purposes. 
 
 Mineral Fuels. — The Coals. — One of the most important 
 of minerals is coal — fossil vegetable matter grown and deposited 
 during the Carlwniferous Age (-see j). Ih^. There are two kinds of 
 coal — Anthracite (from the Latin word anthrax, hard), which is 
 dense and heavy, and burns slowly ; and Bituminous, which is soft, 
 and burns with a bright flame and thick smoke like the nuneral 
 resin bitumen. A third substance called lignite is intermediate 
 between wood and coal ; jet is a kind of lignite. 
 
 Both anthi'acite and bitunnnous coal are found in innnense 
 quantities throughout the world. (On ancient forests and modern 
 fuel, see Anstcd's ''The Oreat Stone- Boo^f nf Nature,'' p. 193.) 
 
 Petroleum, or Rook-Oil.— Crude petroleum is composed 
 of a nund)er of hydrocarbons like naphtha and bitu'men; it also con- 
 tains impurities. It occurs in the stratified rocks of all ages; and 
 geologists are of opinion that it owes its origin to the decomposi- 
 tion of orgaidc; remains, both animal and vegetable, by natural ]iro- 
 cesses of distillation, in the deep-seated layei-s of the earth's crust. 
 
 In some places petroleum oozes up and flows out in springs ; else- 
 where, it is obtained by boring into the earth. A liberal flow of oil indi- 
 cates the presence of a great subterranean reservoir. From petroleum 
 are made, by distillation, kerosene, lubricating oils for oiling machinery, 
 naphtha, paratfiue, and other products of value. {Consult Professor 
 Winchell 's '• Sketches of Creation,^' p. ;277.) 
 
 Rook-8alt is widely distributed through the stratified rocks. 
 It is believed to be pr(j(luced I)y deposit or crystallization from 
 condensing and evaporating bodies of saline waters, and is always 
 nnxed with im|>nrities to a greater or less degree. As a proximate 
 principle, salt is found in every fluid and tissue of the human body 
 except the enamel of the teeth; hence it must Ite supplied freely 
 with articles of food, and is an essential in haliitable regions. 
 
 MINERAL PRODUCTS DERIVED FROM THE SEVERAL ROCK- 
 SYSTEMS. 
 
 (Selected from a Summanj prepared by Professor Page.) 
 
 SYSTEMS OF 
 STR.\TA. 
 
 Quaternary. 
 
 Tertiary. 
 
 Cretaceous. 
 Jurassic. 
 
 Triassic. 
 Carboniferous. 
 
 Devonian. 
 
 Silurian and 
 Cambrian. 
 
 Laurentian and 
 Metamorphic. 
 
 Volcanic Rocks, 
 produced by the 
 dischaiges of 
 volcanic matter. 
 
 INDUSTRIAL PRODUCTS. 
 
 Sand for mortar and glass-making, gravels, clays, marls, 
 peat, bog-wood, guano (mineralized droppings of sea-biids, valu- 
 able as a manure), copal from the soil of old forest-groivths, 
 naphtha, petroleum, asphalt, coral-stone. 
 
 Flint gravels, clays of various qualities, gypsum (plaster-of- 
 Paris), lignites or wood-coals (used for fuel, gas-making, etc.), 
 amber. 
 
 Chalk, limestones, fire-stone.s, lignites, and bituminous coals. 
 
 Brick-clays, sandstones, freestones, flag-stones and tile- 
 stones, iron-stones, jet. 
 
 Alabaster, rock-salt, brine-springs, shell-limestones. 
 
 Sandstones, limestones, bituminous and anthracite coals, 
 iron-ore, veins of lead, zinc, and antimony. 
 
 Sandstones of various colors .and qualities, flag-stones, lile- 
 stones, limestones, metalliferous veins of iron oxide, lead, cop- 
 per, and silver. 
 
 Sandstones, limestones, slates, veins of gold, platinum, sil- 
 ver, mercury, copper, tin, lead, iron, etc. 
 
 Slates, marbles, asbestos, meerschaum, graphite (used in 
 manufacture of lead-pencils), veins of precious and useful metals. 
 
 Lavas (used for building, road-materials, etc.), pumice, ob- 
 sidian, or volcanic glass (used by ancient races for the manu- 
 facture of implements), sulphur, borax. 
 
 Questions, — Explain the province of economic geology ; the relation between 
 a knowledge of the metals and man's progress in civilization. In what 
 forms do mineral bodies occur ? How have tliey been classitied ? Wliat 
 can you say of their distribiUion ? Karae the most important metals. 
 Which are distinguished as preciou)i? Describe gold. How does it occur, 
 and where is it mined ? How do the several gold-bearing localities re- 
 spectively rank in importance ? What is the estimated value of gold now 
 in circulation ? Can you answer the same questions in regard to silver ? 
 What can you say of platinum ? Mercury ? Iron ? Copper ? Lead ? 
 Tin ? Zinc ? Nickel ? Specify tlic various uses of these metals. Com- 
 pounds of whicli are used as medicines ? 
 
 Enumerate the building-stones. Describe the various kinds of limestones. 
 What are sandstones ? Whence come the finest marbles ? What is granite ? 
 What can you say of tlie clays and chalks ? What minerals are derived 
 from fossil vegetation ? Explain the origin of rock-oil ; of rock-salt. 
 
Questions on the Map s 
 tion of Metals and. Precious 
 
 the map above, what metals do you infci 
 over the earth? Point out the looalit' 
 abuudantly. Locate the gold-fields of N 
 Transvaal. What countries of South An 
 What European state produces the most 
 on the slopes of the Ural Mountains S 
 Mountains? among the Pyrenees? In? 
 ica are there silver-mines of great va 
 emerald, and ruby fields? Where else 
 Find the location of the oldest tin-rain 
 Mention the chief lead-producing counti 
 
the DLstribu- 
 
 — From a study of 
 . widely distributed 
 
 gold occurs most 
 :a ; of Australi-.i ; of 
 this precious metal ? 
 at metals are found 
 
 of the Carpathian 
 es of South Amer- 
 ir-uiines ? diamond, 
 
 found? emeralds? 
 iforld ; the richest. 
 
 out the regions in 
 
 which zinc is mined. Give an idea of the wide distribution of iron. 
 Of what sections is nickel characteristic ? 
 
 Where on the map do you find building-stones mentioned ? (See 
 also maps, pp. 12 and 13, 128 and 129.) What is marble? Of what 
 countries is it a product ? What is granite, and how far north is it 
 found ? Where do you find porphyry ? asbestos ? chalcedony ? feld- 
 spar ? mica ? slate ? graphite ? alabaster ? In what regions is volcanic 
 rock met with ? lava ? coral-stone (almost exclusively used for building 
 in the Bermudas)? basalt (out of which Fingal's Cave has been worn 
 by the action of the waves — see p. 22) ? rock-crystal (from which imi- 
 tation gems are made)? kaolin and other clays? copal and amber? 
 cinnabar, or red sulphide of mercury ? bismuth and antimony ? niter 
 and sal-ammoniac ? From what part of the world does meerschaum 
 
 come ? Where iu Africa do you meet with syenite (Scotch granite), 
 from which the ancient Egyptians cut their obelisks ? 
 
 Point out the great coal-beds of the world ; the principal petroleum- 
 fields ; the sulphur-producing regions ; the borax-yielding localities. 
 Where are there valuable pearl-fisheries ? Whence come the finest 
 white pearls ? What grand divisions produce the most precious stones? 
 Where is the opal found? the topaz ? the .sapphire ? onyx? amethyst? 
 carnelian ? malachite ? the turquoise ? What valuable mineral produc- 
 tions are found in Borneo ? in Tasmania ? iu Japan ? in New Zealand ? 
 in Mexico ? in Central America ? in the Dominion of Canada ? Leaving 
 gold and silver out of account, name the grand division that yields the 
 most abundant and most varied mineral treasures. What parts of the 
 earth are most barren of metallic products ? 
 
120 
 
 DIAMONDS AND DIAMOND-FIELDS. 
 
 PRECIOUS STOJfES. 
 
 The Diamoiid. — The most valuable of precious stones is the 
 diamond — pure crystallized carbon — the most highly refractive 
 and the hardest of gems, and the only one that is combustible. 
 This latter property was discovered in 1691 by Cosmo I. of Tuscany, 
 who ignited the diamond with a burning-glass ; and later it was 
 found tiiat when burned in a crucible this gem converts iron into 
 steel. The diamond generally occurs as an octahedron, and sur- 
 passes all other gems in the property of dividing light into colored 
 rays, causing that peculiar flash of prismatic hues called its fa'e. 
 
 Diamonds are rated by 
 the carat. The term carat 
 is derived from the name 
 of certain small legumi- 
 nous seeds which, when 
 di'ied, are quite constant in 
 weight. They were used in 
 India for weighing gems. 
 
 In 1871, the syndicate 
 of Parisian jewelers, gold- 
 smiths, and gem-dealers, 
 suggested .205 of a gramme 
 as the value of a carat ; and 
 this was confu-med in 1877, 
 all the leading diamond- 
 dealers of London, Paris, 
 and Amsterdam, accepting 
 it. The English carat is 
 equal to 3.1683 -h grains 
 (commojily reckoned as 
 3.17 grains) troy, hence 
 there are 151i carats in an 
 English troy ounce. The 
 jewelers' carat is subdi- 
 vided into halves, quar- 
 ters, eighths, sixteenths, 
 thirty-seconds, and sixty- 
 fourths. A quarter-carat is 
 called a grain ; pearls are 
 always sold by the grain. 
 
 The earliest known 
 mention of diamonds is 
 supposed to be that in 
 the Indian epic "Mahd- 
 bharata " {ind-hah'hah'- 
 m-^a), B.C. 1000. Before 
 1728, the date of the dis- 
 covery of the Brazilian 
 mines, all diamonds were 
 brought from India and 
 Borneo. There are three 
 
 distinct diamond-producing regions in India; the familiar word 
 Golconda is not the name of a mine, as jjopularly supposed, but 
 merely the general term for the market where diamonds were 
 bought and sold. To-day all the mines are nearly closed. 
 
 Indian diamonds occur in a conglomerate, and also in alluvial or 
 superficial deposits, together with pebbles, ferruguaous quartz, and jasper. 
 Early methods of mining were very crude. The conglomerate was dug 
 out, and carried to small square reservoirs, raised on mounds, where it 
 was carefully washed and sorted, the wet diamonds being readily recog- 
 nized by their peculiar vitreous luster. 
 
 At present India yields very few stones, while Borneo produces only 
 about three thousand carats annually. Diamonds are also mined in 
 New South "Wales, and are met with in Califoi'nia. the Ural Mountains, 
 
 Diamond-Mining. 
 
 Noi'th Carolina, and Georgia. In 1856, the "Dewey Diamond," that cut 
 eleven and a half carats, was found near Manchester, Virginia. 
 
 South African Diamond-Fields. — By far the greatest 
 poition of the diamonds now obtained come from the mines of 
 South Africa, which were discovered, near Hopetown, in 186Y, by 
 some Dutch children. They are situated in Griqualand West, 
 now a part of Cape Colony, in latitude 28° 40', longitude 25° 10', 
 east, about 610 miles northeast of Cape Town and 500 miles fi'om 
 the sea-coast. Although they are at an elevation of nearly 4,000 
 feet above the sea-level, the heat is excessive during the siunmer 
 months, when tlie work is principally carried on. There are four 
 
 large mines, all within 
 a radius of a mile and 
 a half. The celebi'ated 
 Kimberley covers seven 
 and a lialf acres. 
 
 The African muies 
 were originally worked in 
 individual claims, 3,113 in 
 number, each thirty-one 
 feet square, with a road- 
 way seven and a half feet 
 wide between each pair 
 of claims. These small 
 claims are now consoli- 
 dated into about ninety 
 large companies and pri- 
 vate firms having a gross 
 capital of nearly $50,000,- 
 000. Thirty-three million 
 carats (over six and a half 
 tons) of diamonds have 
 already been taken out, 
 valued in the rough at 
 £45,000,000, and after cut- 
 ting at £90,000,000. The 
 absorption of the smaller 
 by the larger companies (unification) is constantly go- 
 mg on, and it is proposed to consolidate all the com- 
 panies into one gigantic monopoly. 
 
 Ten thousand natives, each receiving one pound a 
 week, are emploj ed m the mines under the supervision 
 of twelve hundred Eui opean overseers. 
 
 The enormous sum of over £1,000,000 is annually 
 expended for labor This mammoth investment of Eu- 
 1 opean capital has been profitable to the shareholder, 
 and it would have been still more so were it not for the 
 thievishness of the native diggers, who, instigated by 
 the vicious whites that congregate on the fields, steal 
 and rhspose of from one-fifth to one-fourth of the en- 
 tire yield More improved methods of surveillance, 
 recently introduced, have diminished this loss. None 
 but authorized agents are permitted to purchase or pos- 
 sess rough diamonds, and a large detective force is on 
 the alert to prevent any infringement of the rules. The lengths to which 
 the natives and their white accomplices go in their fraudulent traffic may 
 be judged from the fact that chickens have been decoyed to the mines 
 by them and made to swallow diamonds. A post mortem recently held 
 on the body of a Cafi're who had died suddenly, revealed the fact that 
 death was caused by a sixty-carat cUamond wliich the native had swal- 
 lowed. (On the mines of Griqualand West, consult Leylancfs "A Holi- 
 day in South Africa,^'' p. 93.) 
 
 Theory of Formation. — At the Kimberley mines, the dia- 
 monds were first obtained on the surface in a yellow earth, the 
 result of the decomposition of strata found 100 feet lielow, and 
 known as " blue stuff." Scattered through it are angular pieces of 
 carbonaceous shale, garnet, mica, etc. At a depth of 600 feet, a 
 
THE GREAT DIAMONDS OF THE WORLD. 
 
 121 
 
 hard rock (peridotite) was found, containing the same shale. This 
 shale has evidently been altered by the action of heat produced by 
 tlie penetration of the volcanic rock t]irou<j;h it ; and this heat, 
 causing the lil)cration of some volatile hydrocarbon, has doubtless 
 produced the diamond. The mines are so surrounded bv carbona- 
 ceous sliale that they form, as it were, 
 " pipes " in the center of it. 
 
 lu the Kimherley mine a depth of 000 
 feet has been readied. The number of 
 obstacles which have been successfully 
 overcome and the novel machinery in use 
 make the mining at Kiuiborley tlie most 
 systematic of the kind in the woi'ld. Prog- 
 ress has been rapid. On the site of the 
 desert there is now a city of 30,000 inhab- 
 itants, with water-works, electric lights, 
 railroads to the coast, and many other 
 improvements of modern civilization. 
 
 Brazilian Mines. — In Brazil, 
 diamonds are found in several locali- 
 ties. At Diamantina, in Minas-Geraes, 
 4,000 feet above the sea, the stones 
 occur usually in the gravel and sands 
 resulting from disintegrated rock. Up 
 to 1850, over 7,000,000 carats, woi-th 
 £11,00(>,000, had been taken from the 
 Minas-Geraes mines alone. Perhaps 
 the entire yield from Brazil may be 
 estimated at 13,000,000 carats, worth 
 £20,000,000. 
 
 The beds of rivers Lave been turned 
 aside to aid in the search for diamonds, 
 but the methods of mining have always 
 been very crude. Little machinery has 
 been used, the work of sorting being 
 performed by slaves, wlio were rewarded for any exceptional find. 
 
 Remarkable Diamonds. — Some diamonds are celebrated 
 for their size or the interesting legends connected with them. The 
 Regent, or Pitt diamond, weighing 136|| carats, and originally 
 purchased by Lord Pitt for £1,000, is the finest large diamond in 
 the world. It was discovered in India, in 1701, and weighed ilO 
 carats in the rough. Valued at 12,000,000 francs, it was the most 
 precious of the French crown jewels, and was one of the few re- 
 tained by the government at the great sale in 1SS7. 
 
 The finest blue diamond is the " Hope," which is almost sap- 
 phire-blue and w^eighs H^ carats. It is an Indian stone and evi- 
 dently ]iart of Tavernier"s blue diamond wliicli was stolen from 
 the Garde Meuble in 1792. It was purchased by Mr. Henry Hope 
 for £18,0011. The Dresden Green Vaults contain the finest green 
 diamond, a pear-shaped 4S|^ carat brilliant, the " Dresden Green." 
 
 Among the largest diamonds is the Orloff in the scepter of the 
 Emperor of Russia, weighing 193 carats. It is fabled once to 
 have formed the eye of an Indian idol, and to have been stolen by 
 a French deserter. In the Rxissian treasury is also the Shah, 86 
 carats. Taverniers Great Table weighed 242^ carats. 
 
 The Tiffany yellow diamond, the largest diamond in America, 
 is a flawless double-cut brilliant. It was found in South Africa, 
 weighs 125f carats, is of a rich orange-yellow color, and is the 
 finest yellow diamond in the world. It is valued at $100,000. 
 
 The " Great Mogul " was described by Tavemier, the famous 
 traveler, in 1678. He states that its weight was originally 793| 
 
 The Tiffany Diamond. 
 
 Nattral Sizk. Crown, Side, 
 
 AND Anctlar Views. 
 
 carats, but in cutting it was reduced to 279^ through the stupid- 
 ity of the cutter, who is said to have been fined his entire fortune 
 for his carelessness. This magnificent stone was named after the 
 founder of the so-calletl Mogul dynasty in India. It has disappeared, 
 though some identify it with the Koh-i-Nur {Mountain of Light), 
 which weighed when first brouglit to England, 186^ carats, but 
 wius reduced by recutting, in 18.^2, to 106Jg^ carats. The Koli-i- 
 Nur, " the great diamond of ronuuice," is now among the English 
 crown jewels. Barbot valued it before recut- 
 ting at £140,0(10. 
 
 A diamond, weigliing 457^ carats, was 
 brought from the Cape in 1884; 
 it has been cut into a brilliant 
 of ISO carats, valued at £200,000 
 The finding of this stone is envel- 
 oped in mystery. The name " Victo- 
 ria " was given to it in honor of the 
 queen, and it is urdoubtedly the largest 
 Itrilliant in the world. {Read Streeter''s 
 , / ''The Great Diamonds of the World:') 
 f Value of Diamonds.— In diamonds, perfect- 
 ly white stones or decided tints of red, rose, green, 
 or blue, are most highly prized. Fine cinnamon, 
 and salmon or brown, black or yellow stones, are also 
 esteemed. If flawless and without tint of any kind, they are termed " first 
 water." If they possess a steely-blue color, at times almost opalescent, 
 they are called blue-white. Such are usually Brazilian stones. Excep- 
 tionally perfect stones are termed gems, and for such there is no fixed 
 value, the price depending on the purity and the bi'illiancy of the stone. 
 Tlie term " first water " varies in meaning according to the class of 
 goods carried by the dealer using it. It is impossible to estimate the value 
 of a diamond by its weight — color, brilliancy, cut, and general perfec- 
 tion of the stone, are all to be taken into account. Of two stones, both 
 flawless and weighing ten carats, one may be worth :J600, and the other 
 112,000. Exceptional stones often bring special prices, whereas otf-color 
 or imperfect stones sell at from l.'iO to $75 per carat, regardless of size. 
 
 The pi'obable value of all the diamonds in the world is about S1,000,- 
 000,000. The world's diamond-trade is carried on by about eight thou- 
 sand dealei-s, with a total stock of not far from $350,000,000. The stones 
 are prepared for market by, perhaps, forty-five hundred cutters and 
 polishers, principally in Amsterdam, Antwerp, Paris, and the Jura. A 
 limited amount of cutting is also done in England and the United States. 
 
 The Ruby and the 
 Sapphire are varieties of the 
 species corundum. The yellow 
 variety is known as Oriental 
 topaz, the green as Oriental 
 emerald, and the purple as Ori- 
 ental amethyst. The two latter 
 forms are rare. The sapphire 
 belongs to the hexagonal sys- 
 tem, is next to the diamond in 
 hardness, and is composed of 
 nearly pure alumina. 
 
 The most highly valued ru- 
 bies, which are of the color of 
 pigeon's blood, are found near 
 ]\[andalay, in Burma. In Cey- 
 lon they occur of a lighter color, and in Siam of a very dark red. Al- 
 though the diamond is more generally esteemed, the rarity of rubies 
 of from three to four carats" weight 'is such that they are worth five 
 to ten times as much as diamonds of the same size. The choicest 
 colors of the sajjphire are the cornflower and the velvet-blue. 
 
 The Victoria Diamond, in the Rough. 
 
 Natural Size. 
 
 (From a photograph.) 
 
122 
 
 MINOR STONES. — GEM-OUTTING. 
 
 The Chrysoberyl gems, next to the sapphire in hardness, include the 
 varieties of yellow, brown, green, and an endless number of intermediate 
 shades. The variety of chi-ysoberyl in which impurities are found be- 
 ;vv6en the layers, or the layers are so arranged by twinning that, if the 
 stone is cut across the layers, the light is condensed in an even line, is 
 .ailed chrysoberyl cat's-eye. 
 
 Beryl is a silicate of glucina and alumina. Golden-colored beryl is 
 found in Maine, Pennsylvania, and Connecticut. When the beryl is 
 
 and invariably have some small central core or nucleus. Round 
 pearls of fine luster and color are very valuable, and their value 
 increases rapidly with their size. 
 
 The finest white pearls are from India, the Persian Gulf, and Pana- 
 ma ; the finest black and gray jiearls, from the coast of Lower California. 
 Beautiful pink-tinted pearls are often secreted by the common brook- 
 mussels. One valued at over $2,000 was found near Paterson, New Jer- 
 sey, in 1856, and quite a number have been met with in Ohio, Tennessee, 
 Kentucky, and Texas, and also in England, Scotland, and Germany. 
 
 The Forms in which Gems are cut, are divided into 
 two groups — those with plane and those with round surfaces. To 
 the first belong the brilliant, 
 step or trap cut, and the table- 
 cut or rose-cut ; to the second, 
 the single, the double, and the 
 hollow caboclion or carbuncle 
 cut. 
 
 k2 
 
 \ 
 
 Pe VPL FISHIN(, PlvRL .ShELLS 
 
 colored with chromium, we have the emerald. The finest emeralds are 
 from the Muso mine, near Bogota, where they occur in a rock con- 
 taining bituminous concretions filled with fossils. This mine has been 
 woi'ked for the past three centuries by Europeans, and was previously 
 operated by natives and ancient Peruvians. 
 
 Some of the finest crystals of emerald known have been found in 
 Alexander County, North Carolina ; one weighing ten ounces, but of 
 small gem value, has been found there. When really fine and flawless, 
 emeralds rank with diamonds in value. {See George F. Kunz's ^^ Ameri- 
 can Gems.'") ' 
 
 Topaz occurs yellow, blue, cherry, green, and white. Tourmalines 
 are found in Brazil, Siberia, and in remarkable perfection at Paris and 
 Auburn, Maine. 
 
 Quartz gems are pure silica colored by iron or other oxides. When 
 pellucid the crystalline varieties are called rock-crystal : when coloi'ed 
 purple or violet by oxide of manganese, amethyst. The crypto-crystal- 
 line varieties of quartz are chalcedony, gray, bluish-gray, or brown, with 
 a waxy luster. When banded with rock-ci-ystal, jasper, etc. , it is called 
 agate. When translucent like horn, yellow, yellowish-brown, or red, it 
 is called carnelian. When in bands of white, gray, and other colors, it 
 is called onyx (used for cameos) ; with moss-like markings produced by 
 oxide of manganese or u'on, moss-agate. Moss-agate occurs in immense 
 quantities in parts of the West ; agatized wood (in which the wood-fibers 
 are changed to agate by the infiltration of silicious waters) is found in 
 Arizona and the Yellowstone Park. 
 
 Noble opal is milky, almost opaque, with a play of brilliant, red, 
 green, orange, and other hues. Hungary, Honduras, and Mexico, are 
 the localities for this stone. When yellow, red, and green colors com- 
 bine like flashes of fire, the name fu-e-opal is given to it. This species is 
 found mostly in Mexico. California furnishes beautiful opalized wood. 
 
 Pearls are small bodies found either in mother-of-pearl shells 
 or in those with a nacreous lining. They are formed either by a 
 disease, by the presence of a parasite, or by an effort on the part of 
 the mollusk to rid itself of some foreign substance which has found 
 its way into the shell. 
 
 Pearls are composed of many layers of carbonate of lime with 
 organic matter between, are not always entirely pearly throughout, 
 
 CROWN. BACK, OR PAVILION. 
 
 The brilliant cut is usually Step or Tea? Cut. 
 
 modified, but when perfect 
 fifty-eight facets are required — thirty-three constituting what is 
 called the crown or upper part, the large facet being termed the 
 table, and twenty-five the back, pavilion, or base. The small 
 facet at the bottom is called the collet or culet, and the edge of 
 the stone the girdle. This form of cut is most ex- 
 tensively used for diamonds, but is occasionally //V, 
 employed for other stones. jVi\/\\\ 
 
 Emeralds, rvibies, sapphires, and other colored stones, Rose. 
 usually have the step-cut, so called from the fact that 
 the facets on the crown are in a step-like series, and below the girdle 
 are three or more diminishing zones terminating in a culet. The en- 
 
 SiNGLE, Hollow, and Doodle 
 Cabochon. 
 
 PAVILION, OR BASE, 
 .SHOWING COLLET. 
 
 Brilliant Cut. 
 
 Brilliant Cut. 
 Side View. 
 
 cabochon or carbuncle cut is that in which the top is rounded off and 
 the back flat, hollowed out, or the same as the top. Garnets, turquoises, 
 opals, cat's-eyes, are cut in this manner. In the rose- 
 cut, the back is flat and the top covered with triangular 
 facets generally from twelve to twenty-four in number. 
 
 Imitation Stones. — Ehine stones, the Lake George, 
 California, Swdss, and Swedish diamonds, with the so- 
 called diamond-coated stones, are all paste or lead glass. 
 
 These imitations have been recently improved by 
 the addition of little metal cups or coatings filled with mercury, for 
 which reason they are known as foil-backs, brilliants, etc., but the hard- 
 ness of all is below that of flint-glass. Paste gems are made 
 of silica and oxide of lead, colored with metallic oxides to 
 produce the required shade of color. 
 
 In doublets, the crown is made of quartz, garnet, or 
 some equally cheajj and hard stone ; but all below this is 
 paste of the desired color, the two parts being joined by cement or fire. 
 
 Imitation pearls are small, blown spheres of slightly opalescent 
 glass, roughened and lined with a preparation made from the scales of a 
 small fish found in Switzerland (the bleak), and then filled vnth wax. 
 
 Questions. — What can you say of the diamond ; its value ; the theory of its 
 formation ; the localities at which it is mined ? Describe some remark- 
 able diamonds. What are rubies ? Sapphires ? Emeralds ? Where are 
 these stones obtained ? Name and describe other precious stones used as 
 ornaments. What are pearls, and whence are they obtained ? Describe 
 the forms in which srcms are cut. How are imitation stones made ? 
 
 ^£ 
 
 ^^ 
 
GEOLOGICAL HISTORY OF THE UNITED STATES. 
 
 -r 
 
 ""^ 
 
 
 »»'>> 
 
 \ 
 
 ) 
 
 I 
 
 V. ^ ■' f 
 
 "■■"■-•"V '- 
 
 Shaded portions shotr islands "'': 
 
 at tlw close of the Archiean Era. 
 
 
 NoiiTH America at the Close of the Arcilean Era. 
 
 TlK' Growth of 
 the Nortli AiiK-rioaii 
 Contiuciit. — It is Ix'- 
 lieved that the eai'tli ex- 
 isted firet as a body of 
 heated vapor. Next it 
 condensed to the condi- 
 tion of ig-neous fluidity, 
 aftei- which a crust was 
 formed over it by cool- 
 ing. Nothing remains 
 of tliis primitive surface ; 
 but from its ruins have 
 been accumulated im- 
 mense masses of crystal- 
 line or granitic mmer- 
 als which are called Ar- 
 chaean rocks (.see p. 
 10). These materials, 
 reclaimed from a uni- 
 versal ocean, became isl- 
 ands, and constituted 
 the foundations of conti- 
 nents. Their emergence 
 was due partly to igneous ])rotrusion, and piirtly to actual uplifting 
 through lateral pressure. 
 
 Tlie first map sliows the a])pc:iiance of thfse islands at tlie close of the Ar- 
 clianin era, for the Contiueut of North America. The largest area occupies the 
 eastern part of the Dominion of Canada, with the Adirondack and Minnesota 
 peninsulas. Nearly parallel to its soutlieastern shore, in what became the At- 
 lantic slope, appeared the narrow strip, 3,000 miles long, from Newfoundland 
 to Alaljam'a. Nearly |)arallel to the southwestern sliore ajipoared the larger and 
 broader island constituting the foundation of the Cordilleras, probably extend- 
 ing l)eneath the present surface to Alaska. Areas of less consequence are Green- 
 land, part of Alaska, and the iron-rocks of Michigan, Missouri, Arkansas, etc. 
 
 Elevatiou of Land being pi-odiiced by lateral pressure, it is easy 
 to undei-staiul how basins may appear between the ridges. Three such 
 dejji'essions originated very early. The one of most interest is encircled 
 by the long Atlantic island and the southern Canadian shore (or, more 
 definitely, the Black Mountains of North Carolina, the Blue Ridge of 
 Virginia, the Highlands of New .Jersey and New York, the Green Mount- 
 ains of New England, the Adirondacks of New York, the Canadian high- 
 lands, and the Minnesota Arcluean ))eninsula). The other basins were 
 those of Hudson Bay and the Cordillei-a-s. 
 
 The Next PJiase of the Growth consisted in the development 
 of a sea-beach around every islaiul, together with the accumulation of 
 the finer sediments in deeper water. This work wa.s performed by rivers 
 and marine waves and currents, 
 and was continued until the ocean 
 was excluded from the basins of 
 the eastern and western parts of 
 the United States, and great thick- 
 nesses of sedimentary rocks were 
 deposited. 
 
 For a time, the land and water 
 showed no signs of life. 
 
 In the Paheozoic era, there were 
 fii'st the humbler forms of marine 
 life, such as sponges, corals, mol- 
 luscous shells, and Crustacea, with 
 sea-weeds ; and afterward, jjower- 
 ful cuttle-fi.sh living in chambered 
 shells, immense fish with enameled 
 plates, and amphibians ; while the 
 land-vegetation, consistmgof pines, 
 ferns, and tree club-mosses, grew 
 luxuriantly, and its remains accu- 
 mulated in beds of coal. 
 
 
 
 fc- 
 
 
 "•f ' 
 
 
 '^■-■v. 
 
 'Z- 
 
 
 '^■. ■ 
 
 
 
 
 
 
 
 
 
 i 
 
 
 
 
 
 
 
 
 ■> 
 
 
 
 
 
 
 i 
 
 
 
 
 □ Bn/ land. 
 
 t 
 
 t. 
 
 
 " \ 
 
 
 
 bf;. 
 
 rZ\ Added dnrh, 
 
 J the 
 
 Cretai'cotis . 
 
 tge. 
 
 '--•.'•- 
 
 ■:-J 
 
 
 
 NopTH America in the Cretaceous Aoe. 
 
 The United States in the Tertiakt Age. 
 
 The Appalacliiau 
 Kevohitioii. — At the 
 close of the Paheozoic 
 era, the long Atlantic 
 island wa.s crowded to- 
 ward Canada, and the 
 early marine deposiis ad- 
 joining w(>re folded in- 
 to long, narrow, level- 
 topped ridges and pla- 
 teaus, extending from 
 the Catskills to Tennes- 
 see and Alabama. These 
 disturbances have been 
 termed the Appalachian 
 revolution, because they 
 gave rise to the peculiar 
 Appalachian Mountains 
 and the great Aiipalachi- 
 an Valley, continuous 
 from the Gulf of St. 
 Lawrence to Alabama. 
 
 Not less im))ortant 
 was the change in the 
 
 life, coeval with the purification of the atmosphere by the withch'awal of 
 carbonic acid. Air-breathing reptiles, birds, and marsupials, swarmed 
 on the new land with its forests of cycads, tree-ferns, and exogen.s. 
 
 The aspect of the continent toward the close of this age of reptiles, or 
 tlic Cretaceous period, is sliown in tlie second map. At its dawn the land 
 occupied two areas, separated by a shallow sea exteniling from Texas to the 
 mouth of the Mackenzie River in the Arctic region. At its close the gap 
 between the two islands was filled, and the two parts were united into one 
 area, extending from the Atlantic to the Pacific, and from the Arctic Ocean 
 to tlie mouth of the Ohio. 
 
 In the Neozoic Kra, tlie additions to the coast have been most con- 
 siderable in the Carolinas and Gulf States, as shown in the third map. A 
 part of this addition — the Georges and Newfoundland banks — is now sub- 
 merged. The force of elevation has been most prominent in the region of 
 the Cordilleras, where the land has been raised bodily thousands of feet with 
 very little increase of area. The map also shows the location of several fre.sh- 
 water lakes. These wore larger at first than subsequently, and they have now 
 dwindled to very insignificant proiiortiuns, as in the Humboldt and Great Salt 
 Lakes. The largest and earliest lay between the Rocky and Wasatch ranges, 
 and was a little later divided by the east and west Uinta Mountains into two. 
 One of considerable consequence lies chiefly in New Mexico, upon the head- 
 waters of the San .Juan River. The largest lake shown ujjon the niaj) was 
 the White River basin, upon the eastern slope, in Nebraska and Ivansas, 
 which existed in the middle part of the age. Others were situated in Colo- 
 rado, Montana, Oregon, Nevada, and 
 elsewhere. The latest were Lake 
 Bonneville, of which Great Salt Lake 
 is the briny residuum, and Lahontan, 
 in Nevada, whose waters contained 
 much lime. 
 
 Mammals of the Tertiary 
 Age. — Around these lakes flour- 
 ished uncouth beasts, suggestive of 
 rhinoceroses, hippopotamuses, ele- 
 phants, bears, etc. — but each united 
 in itself the characteristics of two 
 or more of our common mammals. 
 For instance, one was part bear 
 and part elephant ; another com- 
 bined the features of the deer, cam- 
 el, and pig. Near the close of Neo- 
 zoic time, and contemporary with 
 the earliest men, American mam- 
 mals attained their highest devel- 
 o]imeiu. 
 
PHYSICAL FEATURES OF THE UNITED STATES. 
 
 Geographical Position and Ai*ea. — The United States 
 occupies the middle portion of North America. It extends from 
 the Atlantic to the Pacitic Ocean, and is bounded on the north by 
 the Dominion of Canada, on the south by Mexico and the Gulf of 
 Mexico. It is included between 2i^-° and 49° of north latitude, 
 and spreads over 58° of longitude. Besides this inain body, tlie 
 United States comprises a detached area — the territory of Alaska, 
 which forms the northwestei'n portion of North America, and 
 which extends, in a narrow tongue, southeastward along the Pacific 
 coast nearly to Washington. 
 
 The United States, excluding Alaska, contains an area of 
 3,026,500 square miles. The area of Alaska is estimated at about 
 530,000 square miles ; thus the total area of the United States is 
 approximately 3,556,500 square miles. (On the areas of the States, 
 see Ganneifs ^'■Sulletin of the Tenth Census") 
 
 SURFACE STRUCTURE. 
 
 The Average Elevation of the country, excluding Alaska, 
 is not far from 2,600 feet. Of its area, a little more than one-third 
 has an elevation less than 1,000 feet, about one-fifth has an eleva- 
 tion greater than 5,000 feet, while less than one per cent, is over 
 10,000 feet above the sea. 
 
 The greatest elevation is in the Sierra Nevada, of California, where 
 Mount Whitney reaches an altitude of 14,898 feet. The greatest depres- 
 sions of the surface are not far removed from this region of greatest ele- 
 vation. These are in Death Valley, in southeastern California, and the 
 valley of Soda Lake, in southern California, which are 100 to oOO feet 
 below the level of the sea. 
 
 Primary Features of Relief. — In studying the physical 
 geography of the country, we should first consider its great features 
 of relief, as these determine, to a large extent, its river-systems, its 
 temjDerature, rainfall, and vegetation. 
 
 These primary features are: I. A great elevated plateau or 
 table-land, capped by mountain-ranges, which, with its slopes, com- 
 prises about one-half — the western half — of the country. This is 
 the Cordilleran or Rocky Mountain Plateau. II. A great valley, 
 lying east of the plateau and drained by the Mississippi Eiver 
 and its tributaries, with the Great Lakes. III. A smaller system 
 of elevation lying east of this valley, the Appalachian High- 
 lands, from which the country slopes gradually to the shores of 
 the Atlantic. 
 
 The Cordilleran Plateau. — The western border of the 
 summit of the Cordilleran Plateau is outlined by the Sierra Nevada 
 and the Cascade Range, in Cahfornia, Oregon, and Washington. 
 The eastern border traverses western Texas, eastern Colorado, cen- 
 tral Wyoming, and western Montana, being outlined by the eastern 
 ranges of the Rocky Mountain System. Fi-om its summit, the 
 Great Plains, which form its eastern slope, grade gently down to 
 the Mississippi Yalley. 
 
 The elevation of the summit of this plateau ranges from 4,000 to 
 10,000 feet, being highest in central Colorado. From this highest region 
 the plateau slopes gently in all du-ections — to the southward, so that at 
 the Mexican boundary it is not more than 4,000 feet high — to the north- 
 ward and northwestward, in which direction it drops off to 4,000 feet at 
 our northern boundary. To the westward, it slopes down to the depres- 
 sion drained by the Colorado, beyond which it rises in Utah and eastern 
 Nevada, to sink again in western Nevada and eastern California. 
 
 The surface of the plateau is diversified by a great number of smaller 
 elevations and depi-essions, most of the former being abrupt upon both 
 sides, and therefore to be classed as mountain-ranges. Some of them, 
 however, have gentle slopes upon one side, while the other side is abrupt 
 and chff-like. Such are known as "mountains lying down." 
 
 The Cordilleran Ranges. — The mountain-ranges of this 
 region are very numerous. Indeed, over extensive areas, the coun- 
 try is but a succession of mountains and valleys. Almost all the 
 ranges trend nearly north and south. To this rule there are very 
 few exceptions, and this regular trend indicates that the uplifting 
 forces must have been similar in all cases. 
 
 The bordering ranges, the Sierra Nevada and the Cascade on 
 the west and the Rocky Mountains on the east, are the highest and 
 most massive of the whole system. The first rises in a long intri- 
 cate system of foot-hills from the great valley of California to 
 smnmits ranging from 12,000 to nearly 15,000 feet above the sea, 
 whence it plunges down abruptly to the plateait on the east. The 
 Cascade Range is a line of extinct volcanoes, which commences 
 with Mount Shasta in California, and runs across Oregon and 
 Washington. The range has a general altitude of about 8,000 feet, 
 while above it tower mountain-cones 4,000 to 6,000 feet higher. 
 
 The Rocky Mountains consist of several ranges forming 
 a double and in some cases a triple line, inclosing between them 
 high valleys, known as parks, such as the North, South, Middle, 
 and San Luis Parks, of Colorado. In these ranges, scores of peaks 
 exceed 14,000 feet in height, while hundreds rise above 13,000 feet. 
 
 In southern Wyoming there is a break in the continuity of 
 these ranges — a broad gap, of which advantage has been taken in 
 building the Union Pacific Railroad. The traveler on this road 
 sees the Rocky Mountains only at a distance ; the hills which he 
 crosses at Sherman, and which he rounds in the Laramie Plains, 
 being merely spurs from the great ranges of Colorado. The line 
 of mountains is taken up again in northwestern Wyoming by the 
 Pig Horn and Wind River Ranges, and is continued northward 
 across Montana by the Missouri Range, which extends to the north- 
 ern boundary of the United States. These ranges are not as high 
 as those of Colorado ; the Wind River Range is the highest, hav- 
 ing peaks which reach 13,000 feet, while few mountains in western 
 Montana are more than 10,000 feet above the sea. {Consvlt Gan- 
 netfs '•'■Dictionary of Altitudes in the United States" United 
 States Geological Su7'vey.) 
 
 In southwestern Wyoming a system of low ranges puts off south- 
 ward and westward from the Rockj' Mountains, in the form of a spur 
 from the main system. In Utah these ranges increase in altitude, and 
 become known as the Wasatch, which attains a mean height of 10,000 
 to 11,000 feet. They fall off in southern Utah, and become merged in a 
 series of plateaus, decreasing in elevation southward. 
 
 Stretching eastward from the Wasatch in northern Utah, is a range 
 which is exceptional in the fact that its trend is east and west. This is 
 the Uinta Range, which forms the southern limit of a great desert ex- 
 panse, known as the Green River Basin. 
 
 Between the Wasatch and the Sierra Nevada, the country is trav- 
 ersed by numerous narrow ranges separated by valleys differing in 
 width, but in the main broad. Most of this region— which comprises 
 the western half of Utah, nearly all of Nevada, and parts of eastern Cali- 
 fornia and southern Oregon — is dramed to neither ocean ; its scanty 
 rainfall is either absorbed by the thirsty soil, or evaporates. 
 
 West of the Sierra Nevada and the Cascade Range lies a broad val- 
 ley, separated from the Pacific coast by the Coast Ranges. This valley is, 
 in California, occupied by the Sacramento and San Joaquin Rivere, in 
 Oregon by the Willamette, and in Washington by numerous smaller 
 
RELIEF-MAP OF THE UNITED ST ATES. — SEC TION OF THE UNITED STATES. 
 
 125 
 
 n 
 
 
 
 
 ? • 
 
 .** 
 
 v^' 
 
 
 
126 
 
 THE APPALACHIAN S Y STE M. — CO A ST- LI N E. 
 
 streams. It is terminated on the sovith by an extension or spur from the 
 Sierra Nevada, which swings around to the westward and joins with the 
 Coasfr Rang-es in southern California. 
 
 The Coast Ranges form a system consisting of many ridges, closely 
 parallel to the coast. They range in height from 8,000 feet in Oregon 
 and northern California, to 3,000 feet in southern California. 
 
 The Great Plains. — From the eastern base of the Rocky 
 Monntains, where the elevation of the plateau is from 4,000 to 
 6,000 feet, the country slopes gently and almost imperceptibly to 
 the eastward. This long incline is known as the Great Plains. It 
 is a monotonous, rolling, treeless expanse, stretching in endless bil- 
 lows from the northern to the southern boundary, with a breadth 
 of from 500 to 700 miles. It comprises western Texas, eastern 
 New Mexico, Colorado, and Wyoming, and the greater part of 
 Montana, together with western JSTorth and South Dakota, ISTe- 
 braska, Kansas, and Oklahoma. 
 
 Near the foot of the slope, the Great Plains merge gradually into 
 the prairie region, where luxuriant vegetation takes the place of sparse 
 bunch-grasses, and groves of trees appear as precursors of the foi<ests 
 which cover the country farther east. 
 
 The Great Valley of the United States stretches from 
 the noi-thern boundary of the country to the Gulf of Mexico, and 
 from the western foot-hills of the Appalachian Mountains westward 
 to an ill-defined line along the slope of the Great Plains. The 
 southern and much the larger portion is drained by the Mississippi 
 and a few smaller streams to the Gulf of Mexico. The northern 
 part is drained by way of the Great Lakes and the St. Lawrence 
 Eiver to the Atlantic, with the exception of a small area in Minne- 
 sota and North Dakota, the surplus waters of which flow off by 
 way of the Eed Eiver to Hudson Bay. 
 
 The surface of the valley is generally quite level and uniform. 
 Aci'oss northern Michigan, Wisconsin, and Minnesota, runs a line of 
 elevation, sepai'ating, in part of its course, the waters of the Mississippi 
 from those of Lake Superior. Again, in southern Missomi, northwest- 
 ern Arkansas, and in Indian Territory, there is an extensive, confused 
 mass of hills, rising from 1,.500 to 2,000 feet above the sea. These are 
 known as the Ozark Hills or Mountains. Over much of Ohio, Kentucky, 
 Tennessee, and southern Indiana, the surface is somewhat broken, but 
 there are no hills of any considerable height. Many of the streams of 
 the valley flow between high bluff banks, reachiug in the cases of the 
 Mississipiii and the Missouri, an elevation of 300 to 400 feet. {See Fos- 
 ter ''s "The Mississippi Valley.''^) 
 
 The Appalachian Biountain System, Avliile inferior to 
 the Cordilleras in length, heiglit, and breadth, is a feature of relief 
 of great importance, esj^ecially as it occurs in the midst of a com- 
 pai'atively densely-settled region. The system extends from north- 
 ern Alabama in a northeastern direction through New England, 
 into the Dominion of Canada. Toward the northeast, it loses its 
 character to a great extent, and is represented by short ridges, such 
 as the Green Mountains of Vermont and the Berkshire HiUs of 
 Massachusetts, and by isolated groups, as the White Mountains of 
 New Hampshire, the Adirondacks and Catskills of New York, and 
 the scattered hills of Maine. Throughout New Jersey, Pennsyl- 
 vania, and the southern states, however, it has a well-defined char- 
 acter. It consists of two principal members, the Blue Eidge and 
 the Cumberland or Alleghany Plateau, separated by a long valley. 
 
 The Blue Ridge is the eastern range of the system. It appears first 
 at the Highlands, on the Hudson ; it is cut through by the Delaware 
 River at the Water-Gap, by the Susquehanna near Harrisburg, and by 
 the Potomac at Harpers Ferry. The height of the range increases 
 toward the south, and at the latter point its summit is 1,500 feet above 
 the sea. At the Peaks of Otter, near where the James River finds its 
 way through, the Blue Ridge is over 4,000 feet high. Thus far it is 
 
 single, with a few short, low, outlying chains to the eastward. In west- 
 ern North Carolina, however, it widens out into a perfect complex of 
 ranges and cross-i-anges through which the rivers with difficulty force a 
 passage. In this region are the highest summits of the system. Scores 
 of mountains rear then- heads more than 6,000 feet above the sea, while 
 hundreds exceed a mile in height. Passing into northei'n Georgia and 
 Alabama, the Blue Ridge rapidly falls down into hills, and soon disap- 
 pears in the plain. 
 
 The Appalachian Valley stretches continuously from the Delaware 
 south westward to Alabama. It is occupied in turn by branches of the 
 Delaware, Susquehanna, Potomac, James, and Kanawha Rivers, and 
 finally by the head-waters of the Tennessee. The surface of the valley is 
 in few places level ; it is traversed by numerous parallel ranges and 
 ridges, long, narrow, and sharp, running with remarkable persistence in 
 a uniform direction, for hundreds of miles. These ridges divide the val- 
 ley into numerous long secondary valleys, parallel to the main one. 
 
 The western member of the system is known iu Tennessee and Ken- 
 tucky as the Cumberland Plateau, and in West Virginia and Pennsyl- 
 vania as the Alleghany Plateau or Mountain. It is an inclined plateau, 
 with a well-deflned escarpment or cliff on the southeast, and with a 
 gradual slope toward the northwest. Its western base is not well defined 
 except in the northern part, where the Ohio flows around it. In Ken- 
 tucky and Tennessee, it merges gradually into the comparatively flat 
 country of the Mississippi Valley. 
 
 The Atlantic Plain. — East of the Appalachian System, the 
 country becomes a plain, almost unbroken, except by the beds of 
 streams. Tins plain slopes gently from the foot of the Blue Eidge 
 to the Atlantic. In New England, the Atlantic Plain can hardly 
 be said to exist, as the broken character of the country persists 
 nearly or quite to the sea-shore. 
 
 COAST-LLWE. 
 
 The Sea-coast of the country is varied iii its character. Its 
 lengtJi, including indentations, amounts to 12,600 miles. Of this 
 extent, much the larger proportion, viz., 10,320 miles, belongs to the 
 Atlantic and the Gulf of Mexico (6,860 to the former, and 3,-i60 
 to the latter), while the coast-line on the Pacific is but 2,280 miles 
 in length. If we add to this the shore-line of Alaska (about 8,000 
 miles) and that of the Great Lakes, we have a total of 2i,000 miles. 
 Com]5aring the length of coast-line with the area of the country, 
 we find that there is one mile of coast to each 150 square miles. 
 
 The Atlantic coast is as a whole very broken, with many fine 
 harbors, which have contributed not a little to the high position 
 which our country holds in regard to commerce. The coast of 
 Maine, New Hampshii-e, and Massachusetts as far as Cape Cod, is 
 an exceedingly broken one, being made up of long, rocky points, 
 alternating with deep bays and arms of the sea, and fringed with 
 numbers of islands. Good harbors are numerous. 
 
 In the neighborhood of Cape Cod, on the Massachusetts coast, 
 the character of the sea-shore changes. Thence southward it is, in 
 the main, low and sandy, but it is still somewhat broken, and 
 affords many fine harbors, easy of access, such as those of New 
 York, New Bedford, and Newport. With the shore of New Jer- 
 sey, commences the reef feature, which extends, with occasional 
 breaks, to the end of Florida, and even reappears at many points on 
 the GuK-coast. 
 
 The billows rolling in from the Atlantic, break when they reach 
 shallow water, and deposit the sand held in suspension. In this way 
 there has been bvult up a series of long, narrow, sandy islands or reefs, 
 parallel to the main shore. The arm of the sea inclosed by the reef 
 becomes more or less filled up by material brought down by streams, 
 so that to-day we find areas back of the reefs in all stages of filluag. 
 
THE YUKON AND ARCTIC ALASKA. 
 
 133 
 
 The Yukon is tlie great river of Alaska, and. indeed, is one 
 of the large rivers of the globe. Kising iu the heart of the Cor- 
 dilleras, in latitude 60°, it flows at first northward, gradually 
 making its way out of the mountains, as they trend to the west. 
 Having cleared them, it, too, turns to the west, and then to the 
 southwest, following the general course of the mountain-ranges, 
 and finally enters Bering Sea through a number of mouths, form- 
 ing a delta. It has a total length of more than two thousand 
 miles, nearly all of which is navigable for light-draught vessels. 
 Several large branches in Alaska swell its stream, together with 
 the "White, Pelly, Newberry, and Maemillan rivers in Canada. 
 
 The Yukon Kiver was ex|)lored by Lieutenant Sciiwatka, 
 who floated down its current on a raft from the head-waters 
 to the delta. {Read SckiuatJici' s '■'•Along Alaska's Great River") 
 
 In southeastern Alaska numerous rivei's which head 
 in Canada have cut their way throiigh the mount 
 ains, and discharge into fiords communicating 
 with tlie Pacific. These are navigable only 
 for short distances from their mouths 
 
 Alaska north of the Yu 
 koii, explored in 18S3 by Lieu- 
 tenant Stoney, is very mountain- 
 ous as far up as latitude 68° 54', 
 when the limit of the mount- 
 ains is reached. Beyond this 
 the country is rolling land, 
 with hills from three to four 
 hundred feet high. These 
 elevations decrease in height 
 until latitude 70° 30' north 
 is reached, when the country 
 becomes perfectly level. No 
 rocks are met with beyond 
 latitude 69° 30' north. 
 
 The mountains between the 
 Yukon and latitude 67° north are 
 somewhat detached. Northward, 
 the range is continuous, running 
 nearly east and west. These 
 mountains are the water-sheds 
 of many rivers, some of which 
 are quite extensive. The Al- 
 lastook and the Ko Karchatna 
 unite to form the Koyukuk 
 River, which flows southwest- 
 erly into the Yukon. 
 
 The Inland or Notoak Riv- 
 er, and the Putnam or Kubuk, 
 
 discovered by Stoney in 1S83, both flow in a westerly direction 
 into Hotham Inlet. The Selawik River takes a westerly course 
 and flows into Selawik Lake. 
 
 To the northward are several important rivers belonging to the 
 Arctic System. The Colville, taking a northeasterly course ; and 
 the Chipp, or Ik-pik-puk, discovered by an officer of Stoney's com- 
 mand, in 1886, flowing northerly, are especially deserving of notice. 
 
 The Tundra.— The country in all valleys, lowlands, and to 
 the north of the mountain limit, is tundra, interspersed with 
 numerous lakes. Where the rivers flow through lowlands, the 
 banks are barely discernible, and sometimes the streams spread out 
 over the land for miles. Mosquitoes are the scom-ge of the tundra. 
 
 >*^^ 
 
 Canon of the Yukon, at the Head op Navigation, Eighteen Hundred 
 
 AND Seventy Miles from the Delta. 
 
 (From a photograph by Lieutenant Schwatka.) 
 
 The Natives, by means of the rivers, visit the coast in the 
 spring. Those going south leave the mountains as soon as the 
 rivers break up, in June ; those going to the northern coast follow 
 the reindeer. These animals take to the tundra in summer, and 
 return to the mountains in early winter. The people live princi- 
 pally on fish and the flesh of deer, with the berries and roots of 
 the soil. 
 
 Economic Products. — Cottonwood, birch, and spruce, 
 grow immediately on the banks of the rivers flowing to the south ; 
 but only scrub-willows are foimd about the head- waters of those 
 flowing to the north. Cedar grows in southern Alaska. 
 
 There are many lakes in the mountains, some of them of con- 
 siderable size and depth. Like the rivers, they abound in fish. 
 Salmon swarm in the streams flowing to the south, and codfish on 
 the banks in Bering Sea. 
 
 Gold is found on the Yukon, gold and silver oc- 
 cur in southern Alaska, and traces of gold in 
 the Aleutian Islands. Valuable mines 
 are situated at Juneau and on Doug- 
 las Island. Coal has also been met 
 with in several loeaUties. (On 
 Alaskan fisheries, mineral wealth, 
 etc., compare Hallock's " Our 
 New AlaskaP) 
 
 Questions. — Give the boundaries, 
 area, and shape of Alaska. De- 
 scribe its surface ; its coast ; 
 its principal mountain-system. 
 Where are its highest peaks ? 
 Describe tlie principal river of 
 Alaska. By whom was it ex- 
 plored ? Name the explorer of 
 .Vlaska north of the Yukon. What 
 mountains did he find between the 
 Yukon and the Arctic ? How high 
 are tliey where he crossed them ? 
 From three to four thousand feet. 
 What geological formations predomi- 
 nate in these mountains ? In general, 
 slate with quartz strata. 
 What rivers were discovered by Lieutenant 
 Stoney ? Mention two important rivers belong- 
 ing to the Arctic System. Describe the tundra- 
 land. On what do the natives of Alaska chiefly 
 subsist ? Mention the principal economic prod- 
 ucts of the territory. 
 
 Questions on the Map.— Name the main 
 indentations of the coast of Alaska. How is 
 Sitka situated ? Describe Guyot Glacier ; St. 
 Michael Island ; Nunivak ; Unalaska. What has 
 recently been discovered between Nunivak and 
 St. :Matthew Islands ? A valuable cod-bank. 
 Are there mountains on the northwest coast ? There are no ranges on the 
 coast south of Point Barrow, but rolling hills, increasing iu height toward 
 Cape Lisburne. Where is Mount Logan ? Mount St. Elias ? Where is 
 Chilkoot Pass ? Point out Copper River. From what lake in the Do- 
 minion of Canada do the head-waters of the Yukon issue ? 
 How far north do trees grow ? North of the Allastook there are no trees ; a 
 few bushes are found on the head-waters of the rivers flowing north. Are 
 animals ever found on the tundra ? What fish is abundant in the inlets 
 and streams ? The salmon. What other fish swarm along the coasts ? 
 Where are fur-seals found ? sea-otters ? For what fisheries is Kotzebue 
 Sound noted ? In what parts of the territory is gold found ? silver ? 
 coal ? copper ? cinnabar ? graphite ? What valuable fur-bearing animals 
 are native to Alaska ? what important timber-trees ? what peoples of the 
 Y'ellow Type ? 
 
 
13i 
 
 ANIMAL LIFE OF THE UNITED STATES. 
 
 MAMMALS OF THE UJflTED STATES. 
 
 The Wide Range of Physical and Climatic Condi- 
 tions, wliich, as we have seeu, characterizes the vast territorial 
 domain of the United States, has resulted in producing the utmost 
 \'arietj and profusion of vegetation, and a corresponding abundance 
 and diversity of animal life. 
 
 The ancient group of Marsvipials, or pouched animals {seep. 
 103), is represented in the United States by two species of Opos- 
 sums. One barely crosses our southern boi'der ; the other extends 
 northward to New York, and is common from New Jersey south- 
 ward. 
 
 The Sloths, Ai-niadillos, and Ant-Eaters, are pecul- 
 iarly specialized forms of a lowly oi-ganized group of mammals, 
 which attains its greatest development in tropical America, and 
 sends one representative, an armadillo, as far north as the southern 
 border of the United States. Their abundant fossil remains show 
 that at an earlier period in the earth's history they were much 
 more numerous and diversified than at present. 
 
 The Manatee, or Sea-Cow, is a singular animal, living in 
 shallow water in bays, lagoons, and large i-ivers, and subsisting on 
 aquatic plants. Its fore-legs are modified into paddles, and its 
 hind-legs are obsolete. It was formerly supposed to belong to the 
 whale tribe, from which it is now known to differ widely, both in 
 structure and habits. The Manatee is found on the Florida coast, 
 and measTires about ten feet in length. Other i-epresentatives of 
 the group occur along the west coast of Africa, in the Indian 
 Ocean, and at some of the Austi-o-Malay Islands. 
 
 Steller's Sea-Cow, which measured about thirty feet in length, for- 
 merly inhabited the shallow water surrounding Bering' Island in the 
 North Pacific, feeding upon sea-weed. During the winter of 1768, it was 
 exterminated by the crews of vessels wintering at the island. A number 
 of huge skeletons have been recently brought to our National Museum 
 by Dr. Leonhard Stejneger. 
 
 The group Insectivo- 
 ra is represented by a num- 
 ber of peculiar genera — 
 the Star-nosed Mole, named 
 from a curious circle of 
 tentacle-like feelers on the 
 end of its snout ; the Com- 
 mon Mole ; the Hairy-tailed 
 Moles ; the singular Gibbs's 
 Mole, intermediate between 
 the Moles and Shrews ; and 
 the short-tailed and amphib- 
 ious Shrews. Of the tiny 
 Shrews, no bigger than one's 
 finger, some species range 
 northward beyond the Arc- 
 tic Circle, and remain active 
 throughout the long, cold 
 winters. 
 
 The Bats, the only 
 mammals possessing true 
 wings and the power of 
 flight, are abundant in tem- 
 perate and tropical Amer- 
 ica. Most of them feed on 
 
 The Bison, or American Bcffalo. 
 
 insects exclusively ; but at least one South American species, which 
 extends as far north as Mexico, sucks blood from the larger mam- 
 malia. These bats sometimes do great injury to horses and cattle, 
 not so much from the actual loss of blood they occasion, as from 
 the inflammation which subsequently sets in. 
 
 The Rodents, or gncnoers, are a very large and much diver- 
 sified group, of which several families, many genera, and a great 
 number of species, are peculiar to America. They may be distin- 
 guished at a glance from all other animals by their long, chisel-like 
 front teeth, and by the absence of canine teeth. The Eats and 
 Mice of tlie Old World were early introduced into this country, and 
 have spread over nearly the whole of North and South America. 
 
 The following genera are common to the northern parts of 
 both hemispheres : The Meadow-Mice, Lemmings, Rabbits, Coneys, 
 Beavers, Squirrels, Ground-Squirrels, and Marmots. The remain- 
 der, comprising by far the greater number, are exclusively Ameri- 
 can. The Mouse family alone contains seven peculiar genera. 
 
 The Jumping-Mouse is not a mouse at all, but the type of a distinct 
 family. It is a very pretty animal, with a prodigiously long tail and 
 long hind-legs. It is found from the Atlantic to the Pacific, and from 
 Hudson Bay and Great Slave Lake to Virginia and Arizona. 
 
 Another very distinct family contains the small animals that, for 
 want of a better name, are usually known as " Kangaroo Rats and Mice." 
 They have exceedingly long hind-legs, but their most striking peculiar- 
 ity is their external cheek-pouches, which are lined with fur. This last 
 peculiarity is shared by another family, comijrising the Pocket-Gophers, 
 which have very short hind-legs and live in underground tunnels like 
 the Moles. Both groups inhabit the West and Southwest, but are not 
 found in the Eastern States. 
 
 There remains still another family of Rodents peculiar to Noi-th 
 America. It contains a smgle genus of burrowing animals, called 
 Show'tls. They have broad, flat heads, exceedingly short tails, and are 
 about the size and color of the musk-rat. They are confined to a narrow 
 strip along the Pacific coast from California to British Columbia, and 
 are interesting from then- antiquity. The family has no near relatives 
 among existing mammalia, and must be regarded as a relic of the past. 
 
 The so - called " Prairie- 
 Dogs " are Rodents, related, 
 on the one hand, to the Mar- 
 mots, and, on the other, to the 
 Ground-Squirrels. They live 
 in large colonies on the barren 
 plains of the far West, subsist- 
 ing on such scant vegetation 
 as the region affords. Owls 
 and rattlesnakes take posses- 
 sion of their deserted burrows, 
 and sometimes prey upon their 
 young. 
 
 The arboreal Porcupines, 
 characterized by their spiny 
 armature, inhabit the forest- 
 regions of America, from 
 the limit of trees west of 
 Hudson Bay to Paraguay. 
 The South American spe- 
 cies have long tails, which 
 in most cases are prehensile ; 
 while those from the Unit- 
 ed States liave short, thick 
 tails. They live in trees, 
 and subsist almost wholly' 
 upon leaves and the small- 
 er branches. 
 
HOOFED QUADRUPEDS. 
 
 135 
 
 The Bison. — Tlie most conspicuous of North American 
 mainnials are the Ungulates, or hodfed (|na(h'U]ieds. First of these 
 is the iii.son, or Anieriean BuH'ali), now ra])i(lly apin-oaeliing ex- 
 tinction. It formerly ranged over nearly the whole of the United 
 States ; and in the days of that daring hunter and intrepid explorer, 
 Daniel Boone, it was exceedingly abnndant in Kentucky, where, 
 
 according to his own account 
 of the cane, or cropping the 
 
 he saw it " browsing on the leaves 
 these extensive plains, 
 violence of man.'' Another 
 
 herbage on 
 
 fearless, because ignorant, of the 
 writer, in 1784, said that the herds of Buffaloes which resorted to 
 the salt licks of Kentucky, " by their size and number, fill the 
 traveler with amazement and terror, especially when he beholds 
 the prodigious roads they have made from all quarters, as if lead- 
 ing to some populous city ; the vast space of land around these 
 springs desolated as if by a ravaging enemy ; and hills reduced to 
 plains." 
 
 As late as the beginning of the present century it still existed 
 in parts of West Virginia, Kentucky, and Tennessee, and a few years 
 earlier in western Pennsylvania. The last Buffaloes east of the 
 Mississippi are said to have been killed in northern Wisconsin, in 
 the year 1832, by Sioux Indians. 
 
 Before the railway penetrated to the Pacific, tlie long wagou-traius 
 of emigrants, in crossing the plains, wei-e stopped fi'equently, and for 
 hours togethei', by passing herds of Buffaloes wliieli Ijlocked their way ; 
 and in more recent times, raih-oad-trains were detained from the same 
 cau.se. The number of individuals composing these great assemblages 
 was beyond computation. Formerly immense herds of these animals 
 d<itted the great plains of the West, from the Saskatchewan to Texas 
 aud New Mexico. Their flesh supplied food to the Indian, the ex- 
 ])lorer, and frontier settler ; and their hides were made into clottiing, 
 robes, and the covering for wigwams aud tents — the one animal furnisli- 
 ing both food and slielter. For a time their numbers seemed to defy 
 diminution, hut the white man's greed of gain ha.s proved too much for 
 them. Countless thousands have been butchered for their hides, and 
 now tliey are on the verge of extermination. Two small herds still in- 
 habit the Yellowstone Na':ional Park, and a few exist outside. There is 
 said to be a mountain-race of the Buffalo which lives in deep forests aud 
 never mixes with the Buffalo of the plains ; but this point has not yet 
 been settled. {Consult Allen's " North American Bisons, Living and 
 Extinct:') 
 
 Our Buffalo has a near relative in the Auroch, or European Bison, 
 which was formerly abundant throughout northern EiU'ope, but which, 
 like our own species, has been nearly exterminated, and is now said to 
 be confined to the Caucasus and a small Eussian forest in Lithuania. 
 
 The Rocky-Mouiitaiii Sheep, or Big-horn, is more than 
 twice as large as the domestic sheep, adult males weighing upward 
 of three hundred pounds. The horns of the ram grow to enormous 
 size, while the ewe's horns are small and shaped like those of a 
 goat. The true home of the Big-horn is in rugged, inaccessible 
 parts of lofty mountain-ranges. In the Rocky Mountains it occurs 
 from near the Mexican border to the Arctic Circle, and in the 
 Pacific region from southern California to northern Alaska. The 
 Big-horn has a near ally in the Wild Sheep of Kamchatka and the 
 Stanovoi Mountains. 
 
 The Mouutaiii-Goat is a beautiful animal, about the size of 
 the domestic sheep, but far more slender aud graceful. Like the 
 Big-horn, it is an expert climber, and makes its home high among 
 the mountain- peaks where the hunter follows it with diificulty. 
 It does not occur so far south as the Big-liorn, aud its favorite 
 haunts are at even greater altitudes. It inhabits the higher parts 
 of the Rock}' Moiintains in Idaho and Montana, and the Sierra 
 Nevada in California, and thence extends northward into Alaska. 
 Apparently, it is more common in British Columbia than elsewhere. 
 
 The Mountam-Goat is not a goat at all, but an Antelope, with shin- 
 ing black horns, and clad in long, white hair. Its immediate ancestors 
 are e.xtinct, but it is related, on the one hand, to the chamois of Europe, 
 and, ou the other, to the proug-horued antelope of om- western plains. 
 
 The graceful Prong-horned Antehipe is the type of a 
 distinct family. It is a beautifvd animal, a little larger than a 
 sheep, and inhabits the great plains of the West, over which it 
 iTjanis in herds or droves varying in number from a few individuals 
 to as many hundreds. Its curiosity prompts it to approach objects 
 of unusual appearance, and this habit is taken advantage of by the 
 hunter, who, concealing himself in the grass or behind a rock, and 
 displaying a red handkerchief, sometimes succeeds in drawing it 
 within gunshot. Its flesh is much esteemed. 
 
 The Moose is the largest and most remarkable member of 
 the deer family. It inhabits the coniferous evergreen forests of 
 the northern United States and Canada, extending into the barren 
 groimds iu Alaska. In winter it feeds chiefly upon the bark and 
 branches of small trees which its huge size and peculiarly modified 
 snout enable it to reach and grasp with ease. The Indians prize 
 its flesh, and use its skin in making snow-shoes, moccasins, and the 
 covering of their lodges. The Elk of the north of Europe is a 
 near ally of our Moose. 
 
 The Wapiti, or American Elk, is another noble representa- 
 tive of the deer family. It is smaller than the moose, but very 
 much larger than any of the deer. Though once abundant over 
 almost the whole of the United States and the southern parts of 
 the Dominion of Canada, it is now confined to limited areas in the 
 West, and its utter extermination is greatly to be feared within a 
 few years. The Indians rarely killed more than was needed for 
 their own use, and never caused any appreciable diminution in the 
 nmnbers of any species. Not so with the white man, on whose 
 vandalism it is a lamentable comment that such splendid animals 
 as the Bison and the Elk are now on the verge of extinction. 
 
 Of the Deer proper, there are three species and several 
 varieties, or sul)species, in the United States. The Virginia, or 
 " W^hite-tailed " Deer, has the widest range, being fouml over the 
 whole of the United States and the southern portions of Canada. 
 The Mule-Deer is a western animal, most abundant in the upper 
 Missouri region and west of the Rocky Moimtains ; while the 
 Black-tailed Deer has the most limited range of all, being confined, 
 so far as known, to a narrow sti'ip along the Pacific coast. 
 
 The flesh of all of the deer tribe, called venison, is excellent food, 
 and their hides are made into moccasins, snow-shoes, clothing, aud a 
 variety of articles indispensable to the Indian, and of great value to the 
 frontiersman. 
 
 The Caribon, or Reindeer, is an inhabitant of the far north. 
 It is found throughout the greater part of Canada, from the 
 Atlantic to the Pacific, and it even enters the United States in 
 Maine, New Hampshire, and in the Rocky Mountanis. Its flesh 
 is one of the most important elements in the food-supply of the 
 Esquimaux and the northern tribes of Indians, and its skin furnishes 
 the best material known for the garments of dwellers in Arctic 
 latitudes. A i-elated species is found in the north of Siberia and 
 Europe, and is domesticated and trained as a beast of birrden. 
 {Conqmre Judye Caton^s ^^ Antelope and Deer of America:') 
 
 The Peccaries are small wild hogs, ranging from Texas and 
 Arizona to Paraguay. They are the only American members of 
 the swine family. They usually move in small droves, and when 
 wounded ai-e ferocious and dangerous assailants. 
 
136 
 
 CARNIVOROUS ANIMALS. 
 
 The next group, the Carnivora, contains all the remaining 
 uiainmals. The teeth, in all carnivorous animals, are separable 
 into incisors, canines, and molars, and their crowns are covered 
 with enamel. 
 
 The Walruses and most of the Seals are circumpolar in 
 distribution, being residents of the Ai'ctic Seas of both hemi- 
 spheres. The true Fur-Seal and the Sea- Lions inhabit the IS^orth 
 Pacific. Many thousands of Fur-Seals resort to the Pribilof Isl- 
 ands, oif Alaska, to breed, and most of the pelts which supply the 
 markets of the world are obtained there. The Seals of the North 
 Atlantic are Hair-Seals, and are valuable for their oil and hides, 
 the latter furnishing the material fi-om which most of the so-called 
 " Russian leather " and " patent leather " is made. These animals 
 furnish the Esquimaux with much of their food and clothing. 
 
 The species for whose capture the Newfoundland and Greenland 
 " seal-fisheries " are carried on are the Harp and Hood. The male Hooded 
 Seal is a large and powerful animal with an inflatable proboscis, which 
 it blows up when angry. It is the most savage of the Seals, and when 
 guarding its family on the ice fiercely attacks any one who approaches 
 too near. Related to the Hooded Seal is the Sea-Elephant of the South 
 Pacific, a representative of which inhabits the coast of Lower California. 
 It has been slaughtered for its oil and hide, till now it is on the road to 
 extermination. {Consult Allen's ^' Pinnipedia [Seals mid Walruses]."} 
 
 The Sea-Otter, whose fur is more costly even than that of 
 the fur-seal (single skins being worth about one himdred dollars), is 
 a highly specialized offshoot of the Weasel family, modified for a 
 strictly aquatic life. It inhabits our noithwest coast fiom north- 
 em California to Alaska, and occuis also in Kamchatka and the 
 Kurile Islands. 
 
 The Wolverine, or Glutton, of -sa hich so many curious tales 
 are told, inhabits the boreal coniferous forests of both hemispheres. 
 
 The Skunks range over the whole of North and South 
 America, except the Arctic poitions. They are beautiful animaK, 
 black and white in color. They feed chiefly upon mice and in 
 sects, and are friends to the farmer, notwithstanding the fact 
 that they occasionally steal some of his chickens. 
 
 The American Badger belongs to a dif- 
 ferent genus from the one containing the 
 European animal of the same name, r 
 Our Badger is still found in Ohio 
 Indiana, and Michigan, and 
 thence westward to the Pa- 
 cific. In a north and south 
 direction it extends from 
 the plains of the Saskatche- 
 wan to Mexico or Middle 
 America. 
 
 The Lynxes, Wolves, 
 Foxes, Sables, Weasels, Fer- 
 ret, Mink, and Otter, of 
 North America, though spe- 
 cifically separable from their 
 European congeners, are not 
 sufiiciently different to mer- 
 it special notice. {ConstiU 
 Richardso7i^ s '■'■ Fauna Bo- 
 reali-A jnericana. " ) 
 
 the Eastern States, and " Mountain-Lion " in the West, deserves 
 special mention, from the fact that it is the largest representative of 
 the cat family inhabiting the United States. It is true that the 
 Jaguar, the largest of American Cats, has been taken along our 
 soiithern border, but it can be regarded only as a very rare straggler 
 from the trojjics. The head of the Cougar is round and cat-like, and 
 it lacks the mane, which gives the true lion much of its majestic 
 appearance. The normal food of the Cougar consists of the various 
 sj^ecies of deer, which it captures by stealthily creej)ing within 
 leaping distance and springing suddenly upon their backs. Along 
 the frontier it often commits serious depredations, by carrying off 
 colts, calves, sheep, and pigs. Its range is remarkable ; it is found 
 from Patagonia to Canada. {Bead Merriatri's " The Mammals of 
 the Adirondack Region" p. 29.) 
 
 Of the Bears, the Polar or Ice Bear is circumpolar in distri- 
 bution, inhabiting the Arctic regions of both hemispheres, and prey- 
 ing chiefly upon seals. The Black and Grizzly Bears are not found 
 except in America, though the former has a near relative in Siberia. 
 
 The Raccoons are exclusively American, and inhabit both 
 North and South 
 America. A relat- 
 ed genus contains 
 the beautiful ling- 
 tailed Raccoon-Fox 
 of Mexico, which 
 extends northward 
 into California, Ari- 
 zona, New Mexico, 
 and Texas, and has 
 been found even 
 m Ohio 
 
 The Cougar, or Pu- 
 ma, called " Panther " in 
 
 Elk, Black-tailed Deer, Prong-horned Antelope, Rocky-Mountain Sheep, Mountain-Goat. 
 
VEGETATION.— MINERAL WEALTH. 
 
 137 
 
 Fossil 3Iaiiiiiialiji.— Xo i>:irt of the woi-ld is riclicr than 
 America in fossil renwius of tlie higher vertehrates. In compara- 
 tively recent times, elephants, mastodons, wild horses, and several 
 species of bison now extinct, were abundant in North America ; 
 and in the western United States the deeper strata reveal the 
 former ])rcsenco here of camels, rhinoceroses, and other animals 
 now found only in tropical jxirts of the Old "World, together with 
 Avhole families totally unliico any existinj; kinds ; and others, still, 
 which tlirow much light on tlie ancestry of most groups of living 
 mammalia. 
 
 Numerous connecting' links have been discovered showing the rela- 
 tion between forms now widely distinct, bridging- over many of tlie gaps 
 supposed to separate the larger groups, pointing out the line of their evo- 
 lution, and breaking down many of the liard and fast lines by ^vhich 
 they wrro formerly characterized. 
 
 Fossil bones of tlie progenitors of the modern horse, reaching fai' 
 back in time, have been fomid in gi-eat abundance in certain parts of the 
 West. Tliese fossil remains furnish an excellent exanii)le of a series of 
 conuecting links, showing the steps by which a small, four-toed quad- 
 ruped has become gradually modified into a large, single-toed animal 
 specialized to attain a high rate of speed. 
 
 (On the Birds of the ITnited States, consult Baird, Brewer^ 
 and Bidgwai/^s '■'■ North American Birds') 
 
 VEGETATIOJ^. 
 
 Native Food-Plants. — None of the plants that produce 
 the great staples of commerce are natives of the United States. 
 Edible small fruits, such as the strawberry, raspberry, blackberry, 
 and huckleberry, are indigenous and widely distributed. 
 
 Excluding Alaska, we may divide the United States, as regards 
 character of vegetation, into live regions, three of them forest-clad, 
 and two distinguished by an absence of trees. 
 
 Forest - Regions. — I. The region cast of the Mississippi 
 River, with the exception of most of the State of Illinois. This is 
 now the most densely populated portion of the continent. In many 
 parts, the forests which originally existed have been cleared, and 
 have given place to faiTns. In the northern part, the forests are com- 
 posed of pines, firs, hemlocks, birches, and poplars ; in the central 
 portion, oaks, chestnut, maple, black-walnut, button-wood, and tulip- 
 tree prevail ; while in the south, in addition to these latter, many 
 other species occur, notably magnolias, bald cypress, and palmetto. 
 
 II. The Rocky Moun'.ain Region, a belt of country extending 
 from western Texas and New Mexico to Idaho and Montana. 
 Here the forests are mainly coniferous, pines and spruces being the 
 most abundant trees, with some poplars and birches. 
 
 III. The Pacific Region, embracing the Sierra Nevada and 
 Cascade Mountains and the Pacific coast area. Here arc found the 
 most majestic forests of North America. They are mainly conif- 
 erous, consisting of pines, hemlock, firs, and the gigantic redwood 
 and mannnoth trees of California. Oaks and maples also occur. 
 
 Forestless Regions. — I. The Prairies and Great Plains of 
 the central portion of the continent, extending from the Rocky 
 Mountains eastward to the Mississippi Valley, and including, also, 
 most of Illinois. The natural vegetation consists mainly of grasses, 
 an abundance of other herbaceous plants, and some shrubs. There 
 are no forests, but trees grow to a limited extent along the rivers. 
 
 II. The Great Basin Region, lying between the Rocky Mount- 
 ains and the Sierra Nevada, and extending from Arizona to the 
 
 British boundary. Much of this territory is desert, supportinsf 
 sage-bush, grease-woo J, cactuses, yuccas, and other herbaceous and 
 VNoody plauis. 
 
 The Pacific coast of southern Alaska has a very moist climate, and 
 is heavily wooded, piues growing to an enormous size. The interior 
 and noi-thcru coasts of the territory are cold and barren, tbe cliaractcr 
 of the vegetation being that of all Arctic regions. On the southern 
 coact, bar.cy and garden vegetaulej are raised. 
 
 Vegetable Products. — Of spontaneous products, the most 
 important are the various woods, yielding lumber ainiually to the 
 value of more than |200,000,0()0. The cultivated products in- 
 clude Indian corn and the other grains, potatoes, cotton, hemp, 
 hay, sugar-cane, and tobacco. Indian corn is our most important 
 grain-crop, and is raised in the greatest quantities in the Ohio and 
 u]iper Mississippi Valleys. The annual yield is more than two 
 billions of bushels. 
 
 Wheat is grown in almost all the Northern States and on the 
 Pacific coast. Rje, oats, and buckwheat, are also widely culti- 
 vated in the North. Rice is raised exclusively in the Southern 
 States, the product being more than l(»o,(i(i(i,OuO pounds annually. 
 
 Potatoes are mainly cultivated in the Northern States, and sweet- 
 potatoes mostly in the South. Cotton is the most important crop of the 
 Southern States, from 7,000,000 to 9,000.000 bales being produced annu- 
 ally. Hemp and flax are largely grown in the Southei-u and Western 
 States respectively, as is hay in the Middle and Western. 
 
 Tbe cultivation of sugar-cane is conflned -mostly to Louisiana; sor- 
 ghum is widely grown in the North and South Central States, and in 
 the North considerable sugar is made from the sap of the sugar-maple. 
 Tobacco is raised in many parts of the United States, but most abun- 
 dantly in the South Central and South Atlantic States. 
 
 Large quantities of tropical fi-uits and garden vegetables arc pro- 
 duced in Florida, oranges being a characteristic crop. 
 
 MIJ^EHALS. 
 
 The Mineral Wealth of the LTnited States is phenomenal. 
 Coal, iron, silver, gold, petroleum, copper, and lead, are widely 
 distributed. Besides these substances, there are mined large 
 quantities of zinc, quicksilver, and salt; while nickel, cobalt, man- 
 ganese, chromium, and other scarce metals, are produced in small 
 amount. 
 
 The total value of the mineral production of the countr}', in 
 1896, was nearly $747,000,000. Of this enormous sum, the value 
 of the coal mined was about one-fourth ; that of iron, a little more 
 than one-fourth ; while silver and gold contributed respectively 
 about one-ninth and one-nineteenth. 
 
 Coal occurs in beds, stratified, like other rocks. It is one of 
 the most common and widely distributed of all nnncral products. 
 Both the anthracite and bituminous varieties are mined ; most of 
 the former in Pennsylvania. The latter is mined in greater or 
 less quantity in twenty-tiine of the states and territories; but of 
 all these, Pennsylvaiua is the largest producer. Bituminous coal 
 is fouiul in all ]>arts of the Cimiberland Plateau, from Pennsyl- 
 vania to Alabama; it underlies the greater portion of the northern 
 half of the ]\Iississippi Valley, and it aboimds upon the Western 
 Plateau. Cannel coal is mined in Kentuckv. 
 
 In the United States the coal-basins have a known area of not less 
 than 150,000 square miles, and ours is one of the great coal -producing 
 countries of the world. In addition, we have not less than 100,000 square 
 miles of productive coal ai-eas in the rocks of the Cretaceous and Ter- 
 tiary Systems west of the Rocky Mountains. 
 
13S 
 
 MINERAL PRODUCTS. 
 
 The total production of coal in" 1896 was about 180,000,000 short tons, 
 of which nearly 49,000.000 tons were anthracite, 137,000,000 tons bitumi- 
 nous, and 55,000 tons cannel coal. Our country is excelled in coal-pro- 
 ductiou only by Great Britain. Of the amount miiied in the world, we 
 produce nearly one-third. 
 
 Iron is the most generally distributed of the metals. Its ores 
 are widely found, but not everywhere in such location and purity as 
 to make the mining and smelting of them profitable. It is mined 
 in twenty-four of the states and territories ; principally, however, 
 in northern Michigan and Wisconsin. In 1S96, the Lake Supe- 
 rior region produced about two-thirds of the total product of nearly 
 15,000,000 long tons. Pennsylvania, Ohio, Illinois, Alabama, and 
 New York, also mine large amounts. In the production of iron 
 and steel, tlie United States is nearly equaled by Great Britain. 
 
 The Precious Metals are found mainly among the moun- 
 tains of. the Cordilleran Plateau. A small amount of gold and sil- 
 ver is mined upon the Atlantic slope, principally in the Carolinas, 
 in Georgia, and Alabama. In 1896, the United States exceeded 
 all other countries in the production of gold and silver. The value 
 of the gold produced was nearly $53,000,000 ; California leading 
 with more than $15,000,000. In the amount of silver produced, 
 Colorado stands at the head with 8,500,000 fine ounces. The 
 United States is the largest silver producer in tlie world. 
 
 Petroleum, or rock-oil, is contained in strata of porous rocks, 
 and in subterranean cavities. The oil is reached by boring wells 
 down to these reservoirs, wdien it either flows to the surface, or is 
 drawn up by pumping. It is collected into large tanks, and dis- 
 tributed mainly by means of lines of pipes, connecting the regions 
 of production with the great cities. This method of moving tlic 
 crude oil does away with handling it in barrels. Petroleum is 
 almndant in northwestern Pennsylvania, southwestern New York, 
 Indiana, Oliio, and West Virginia, and is found in several other 
 states. In 1896, the product was over (50,000,000 barrels. 
 
 In many localities in the oil-fields natural gas has been discovered, 
 and a number of cities in Pennsylvania, Indiana, and Ohio, use it foi' 
 fuel and light. 
 
 Copper is mined chiefly in Montana, in northei'u Michigan 
 (on the shores of Lake Superior), and in Arizona. In 1896, the 
 Montana mines yielded about one-half the total amount of copper 
 (260,000 long tons) produced in the country. In MoTitana and Ari- 
 zona, carbonates and sulphurets of copper are mined and smelted. 
 
 Lead and Zinc. — Nearly 170,000 short tons of lead were 
 produced from United States ores in 1896. This came mainly 
 from Colorado and Utah, where it is mined in Connection with sil- 
 ver, the silver-ores being lead-ores as well. Smaller quantities are 
 produced from districts in Missouri, northwestern Illinois, south- 
 western Wisconsin, and southeastern Kansas, where the ore is 
 found in irregular deposits, associated witli zinc-ores. The total 
 product of zinc, in 1896, was about 70,000 metric tons, four-fifths 
 of which came from these mines, the remainder being from New 
 Jersey and other Eastern States. 
 
 The only ore of Quicksilver is the sulphuret, known as cin- 
 nabar. Mines of tliis metal are worked in the Coast Ranges of 
 California, and their production in 1896 was moi-e than 33,000 
 flasks, or 3,525,000 pounds. 
 
 Tin-Ore has been found in a few localities in the United 
 States, but nowhere in sufficient quantities for profitable mining. 
 In the Black Hills of South Dakota, several mines have been 
 opened, but they are not worked to any great extent. {See Lud- 
 loio's ''Black Hills of Dakota.") 
 
 Salt is obtained mainly from saline springs and wells, by evapo- 
 ration. In this way immense quantities are manufactured in west- 
 ern New York, Michigan, Ohio, and Kansas, and to a small extent 
 in other states. Rock-salt is mined in the^Warsaw district of New 
 York, in the Hutchinson district of Kansas, and in Avery and Jef- 
 ferson Islands in southern Louisiana, in Utah, and in California. 
 The total production of salt in 1896 was more than 13,000,000 
 barrels. New York holds the first rank as a producer of salt. 
 
 Precious Stones. — In the United States, the production of 
 
 precious stones is confined chiefly to the output of sapphire and 
 rubies from Montana, and turquoise from New Mexico. The 
 value of these gems in 1896 amounted to about $20T),000. Sap- 
 phires and rubies are also found in North Carolina, Georgia, south- 
 ern Colorado, and Arizona. 
 
 Agates, fossil coral, chlorastrolites, and Thompsonite^ are col- 
 lected on the Minnesota and Michigan shores of Lake Superior. 
 Turquoises of trifling value are sold in Santa Fe, and by the In- 
 dians along the line of the Arizona and New Mexico railroads. 
 
 ftuestions. — How do you account for the abundance and diversity of animal 
 life in the United States ? By what are the Marsupials rejjresented ? 
 What is the manatee, and where is it met with ? Give an account of 
 Steller's sea-cow. What representatives has the group Insectivora in the 
 United States ? Describe the only mammals endowed with the power of 
 flight. What sjiecies of rodents are familiar to you ? Describe the 
 prairie dog. 
 
 What can you say of the bison — its former range and present numbers ? Is 
 there a distinct mountain-race of the buffalo ? State the habitat and 
 peculiarities of the Rocky Mountain sheep; of the mountain-goat; the 
 prong-horned antelope ; the moose ; the elk ; the caribou ; the white- 
 tailed, black-tailed, and mule deer. {Compare Physical Map of the United 
 States, ppi. ISS, 1S9.) What animals are inchided under the head of Car- 
 nivora ? What can you say of the walruses and seals ? Of the sea-otter ? 
 Of the American badger ? Of the puma ? Of the bears and raccoons ? 
 Of fossil mammalia ? 
 
 What food-plants are native to the United States ? Into what regions, as 
 regards character of vegetation, has the country been divided ? Specify 
 the Forest regions (see Maj), pp. ISS, 129) ; the Porestless regions. Enu-. 
 merate the characteristic products of each; also, the most important crops 
 of the United States. 
 
 What are the principal mineral products of the United States ? (See Map, pp. 
 128, 129.) What is their value, and what representation in this sum have 
 coal, iron, gold, and silver ? Where is coal found and mined ? What 
 was the production of coal in 1896 ? Where is iron found and mined ? 
 Where are gold and silver mined ? What proportion of the world's prod- 
 uct of precious metals is mined in the United States ? Where is petro- 
 leum found ? How is it obtained and transported ? What is the annual 
 product ? What use is made of natural gas ? Where is copper mined ? 
 Where are lead and zinc found ? What is the annual production of these 
 metals ? Where is quicksilver mined ? What was the production in 
 1896 ? What is the ore of quicksilver called ? Where is tin found ? 
 From what source is salt produced ? Where ? Describe the salt-mines in 
 Louisiana. What was the production of salt in 1896 ? 
 
 Questions on the Physical Map of the United States (pp. 1S8, 120).— 
 What regions distinguished for certain products are shown on this map ? 
 In what part of the United States is the mineral region 1 Where else ai o 
 valuable minerals met with ? Are metallic ores generally found in high- 
 lands or lowlands ? Point out the lumber region ; the wheat region. 
 What animals are native to the pasture region ? Where are fur-bearing 
 animals found ? In what part of the country is the raising of domestic 
 animals a characteristic industry ? 
 
 Trace the isotherm of 56°. Why does it bend southward from the Susque- 
 hanna ? then northward, passing through Indiana and Illinois ? Why 
 does it curve southwesterly from Kansas until it crosses the Texas bound- 
 ary ? Follow the isotherms of 40° and 64°. Why are they not charac- 
 terized by as great irregularities ? South of what isotherm does the 
 cotton region principally lie ? The rice region ? 
 
COMPARISON OF GEMS. -KEY TO GEOLOGICAL CHART. 
 
 139 
 
 TABLE SHOWING APPROXIMATE COMPOSITION, COLOR, SPECIFIC GRAVITY, AND RELATIVE HARDNESS, OF GEMS. 
 
 Diamond 
 
 Sapphire 
 
 Ruby 
 
 Ohrysoberyl . . . 
 
 " cat's-eyo. 
 
 Alexandrite . . , 
 
 Spinel 
 
 Topaz 
 
 Beryl 
 
 EmeraM . . . 
 
 Afpiamarine. . 
 Zireou 
 
 Tourmaline. . , . 
 
 Phenacitc.. . . 
 iiarnct 
 
 lolite 
 
 Clialcedony. . . . 
 
 Agate 
 
 Jasper 
 
 Essonite 
 
 Jadeite 
 
 Spodumcnc 
 
 Quartz 
 
 Ametbyst 
 
 HirJ- 
 nes8. 
 
 10 
 
 Specific 
 gravity. 
 
 3.52 
 
 
 
 8.8 
 8.5 
 85 
 8.5 
 
 4 
 4 
 
 ( 3.76 
 
 3.7 ■ 3.76 
 
 ( 3.65 
 
 8 
 8 
 
 3.65 
 3.55 
 
 1 7,8 
 
 2.7 
 
 7.8 
 
 2.7 
 4.1 to 4.6 
 
 7.5 
 
 3.1 
 
 7.5 
 7.3 
 
 2.97 
 3.75 
 
 7.3 
 
 2.63 
 
 7 
 7 
 
 2.66 ■ 
 
 3.66 
 3.35 
 
 7 
 
 3.2 
 
 7 
 7 
 
 2.65 
 2.66 
 
 Colors. 
 
 White, red, preen, 
 black, pink, blue, 
 brown, etc. 
 
 Blue, shade.< of. 
 
 Red, shades of. 
 
 Yell' w,browu,p:reen 
 
 Darli-grecn by day, 
 
 coluuibine-rcd by 
 
 night. 
 
 Red. blue, gre'n, etc. 
 
 Yellow, blue, pink, 
 
 white, etc. 
 
 Velvet-green. 
 
 Sea-blue and green. 
 Red, brown, yellow, 
 
 greenish - white, 
 
 etc. 
 Red, brown, yellow, 
 
 greenish - white, 
 
 etc. 
 White. 
 Red, purple. 
 
 Blue one way, white 
 
 the other. 
 Gray, bluish-gray, 
 
 yellow, brownish- 
 
 bhic, etc 
 Honey-yellow. 
 E.ncrald, leek-gr'n. 
 
 Yellow, green, and 
 
 colorless. 
 Colorless, smoky. 
 Purple, pink, violet 
 
 Composition. 
 
 Carbon. 
 
 Alumina. 
 
 Alumina, 76; glucina, 18; 
 ferrous oxide, 4; with trace 
 of chromium. 
 
 Alumina, 72 ; magnesia, 28. 
 Silicon, 15.5; oxyg.n, 30.8; alu- 
 minium, 30.2 ; fluorine, 17.5. 
 
 Silica, 66.8; alumina, 19 1 ; 
 glucina, 14.1. 
 
 Zirconio, 07 ; silica, 33. 
 
 Boro-silicate of alumina, lime, 
 
 soda, lithia, with fluorine 
 
 and ferric-oxide. 
 Silica, 54.2; glucina, 45.8. 
 Magnesia, iron, lime, alumina, 
 
 silica. 
 Silica, 49; ferrous oxide, 7; 
 
 magnesia, 9 ; alumina, 32. 
 
 Silica with oxides coloring. 
 
 Lime-alumina garnet. 
 
 Silica, 59 ; alumina, 23 ; with 
 magnesia, lime, soda. 
 
 Silica, 64.2 ; alumina, 29 ; ox- 
 ide Of iron, 4 ; lithia, 6. 
 
 Silica. 
 
 Trace of manganese oxide, or 
 iron. 
 
 Tiger-eye 
 
 Pyritc 
 
 Jade 
 
 Ileniatife 
 
 Labradorite 
 
 Peridot 
 
 Moonstone 
 
 Obsidian .... . . . 
 
 Demantoid, or 
 
 Green-garnet.. . 
 
 Turquoise 
 
 Opal 
 
 Lapis-lazuli 
 
 Malachite 
 
 Marble 
 
 Coral (precious). 
 
 Pearl 
 
 Amber 
 
 Alabaster 
 
 Hard- 
 ness. 
 
 Specific 
 gravity. 
 
 7 
 
 3 
 
 6.5 
 6.0 
 
 5.2 
 3 
 
 6.3 
 6.3 
 
 5.3 
 
 2.72 
 
 6.3 
 
 3.38 
 
 6.3 
 
 2.58 
 
 6 
 
 2.4 
 
 |-« 
 
 3.85 j 
 2.75 
 
 6 
 
 6 
 5.2 
 
 2.20 
 2.4 
 
 4 
 
 * 
 
 o 
 
 2.6 
 
 3 
 
 
 3 
 
 2.7 
 
 2.5 
 
 1.08 
 
 2 
 
 2.32 
 
 Colors. 
 
 Indigo-blue, yel- 
 low, green, brown. 
 
 Brass-yellow. 
 
 White, green, or 
 with blue tinge. 
 
 Metallic black. 
 Gray, with play of 
 
 colors. 
 Olive-green. 
 
 White, with pearly 
 rcflectiiins. 
 
 Brown, black, mot- 
 tled. 
 
 Yellow, green, em- 
 erald-green. 
 
 Sky-blue, blue- 
 recu, green. 
 
 Wbitc-ycllow, etc. 
 Azure blue. 
 
 Green. 
 
 Yellow, brown, 
 gray, etc. 
 
 Red, yellow, pink. 
 
 White, gray, rose, 
 black, brown. 
 
 Yellow, brown, 
 Ijlack, white. 
 
 White, pink, yel- 
 low. 
 
 Composition. 
 
 Silica, 51 ; oxides of iron, 34. 
 
 Sulphur, 53,3; iron, 46.7. 
 
 Silica, S.s ; magnesia, 27 ; soda, 
 12; oxide o^ iron, alumina, 
 etc. 
 
 Iron, 70 ; oxygen, 30. 
 
 Silica, 65.5; soda, 4; alumina, 
 26.5; iron, 31 ; lime, 11. 
 
 Silica, 41 ; magnesia, 60; fer- 
 rous oxide, 9. 
 
 Silica, 64 5; alumina, 18.5; 
 potash, 17. 
 
 Silicate of potash and alumina. 
 
 Silicate of iron, lime, traces of 
 alumina and magnesia. 
 
 Oxide copper, 5.3 ; oxides of 
 iron and manganese, 2.5; 
 alumina, 40.2 ; water, 19.3 ; 
 phosphorus pentoxide, 32.8. 
 
 Silica, 90; water, 10. 
 
 Silica, 49; alumina, 11; oxide 
 of iron, 4; lime, 16 ; sulphu- 
 ric acid, 2. 
 
 Copper oxide, 72 ; carbon di- 
 oxide, 20; water, R. 
 
 Carbonate of lime, 98 ; color- 
 ing and impurities, 2 and 
 over. 
 
 Carbonate of lime, magnesia, 
 trace of organic matter. 
 
 Carbonate of lime witli organ- 
 ic matter. 
 
 Carbon, 79; hydrogen, 10.5; 
 oxygen, 10.5. 
 
 Sulphuric acid, 44.8 ; lime, 33 ; 
 water, 21. 
 
 EXPLANATION OF GEOLOGICAL CHART, PAGES 11 AND 12 
 
 ARCHAEAN 
 
 MESOZOIC 
 
 I^EOZOIC 
 
 Huronian. — a, b^ Eozonn : Earliest re- 
 mains of organized lite ; its nature is un- 
 certain. 
 
 Cambrian.— a, Paradoxides Davidis: a 
 trilobite ; a cru.stacean two feet long belong- 
 inir to the lobster family, i, OUlhamia an- 
 tiqiia: a sea-weed, c^ Hi/menocai'is vei'mi- 
 niddn: acriistaccan; lobster family, d^ Old- 
 hatnia I'adi-itu- : a sea- weed, e^ Agnostus 
 princeps: an invertebrate. ./*, Olenus 7ni- 
 (^ursiis: a trilobite. f/, Obelelli nana: a mol- 
 lusk. ^, Theca corrugatax a pteropod. i, 
 Liiujula prima : a molhisk. y, Lingula 
 Davisii; a mnlluslc. 
 
 Lower Silurian. — a, Ortkoceras: a ce- 
 phalopod ; cuttle-fish family, i, Orthos 
 l<jnx: a mollu--k. c, TivniasCer ."pinosa: a 
 star-fish. </, Hnthotrephis gracilU: a sea- 
 weed, e, Amphtis Poicinii'. a trilobite crus- 
 tacean. ,/', BnthotrcphU 8>iccuiosis: a sea- 
 weed. j7, Mnlnria magna: a mollusk. A, 
 Murchisoiii'i bicinctn: gastcropod. i, C^r- 
 tolUes compnssds: gasteropod. 
 
 Upper Silurian and Devonian. — ff, 
 L^fcopoda: a pl.ant h^ Behmites siilcatns: 
 a ce[)!iaIopOLl. c. Conifer: pine-tree fami- 
 ly. (/, Zaphreiitis Ii'njin&figuii : a polyp. 
 e, Buca/ia Irilohata : a mollusk. f^ Cephas- 
 pis Lyellii: a fish, g^ Lituitescornuariates: 
 
 a mollusk. A, Dabnania Iwivlurus: a tri- 
 lobite crustacean, i, Homalonotus deJphino- 
 cephalus: a trilobite crustiicean. /, Astero- 
 ph;/llites: an extinct plant, i, Pterichthys 
 Millerii : a crustacean. ^, Evrypteim^ Pl/9- 
 moii/s: a crustacean, m, Algtv: sea-weed. 
 ?;, Halysites caitfnilarius: chain-coral, o, 
 Evri/ptervs remipes: a crustacean. />, Al- 
 get: sea-weed, j, Placodermata : a fish. 
 r, Spirifer Niagarensis: mollusk. «, Ca- 
 ryocrinus ornatus: a crinoid sea-lily, t^ 
 Ichihyocrinus levis: a crinoid sea -lily, v^ 
 Catamite: a gigantic extinct mai'sh-plant. 
 ;», Pterygotus Anglicus: a crustacean, w, 
 Spirifer mucrnnolHS abrachiopod. .r, Pla- 
 tyceraa a7}g>ilntiim: a gasteropod. y^ Pi>ilo- 
 phytori : a plant. 2, Platyceras di-mvo&niju : 
 a gasternpod. (g-^ Spirifer culfrijugatus: a 
 mollusk. 
 
 Carboniferous. — a, Anniilirin: aplant. 
 b^ Archegosaurus: a lizard, e, PaUvechinvs 
 gigas ; a sea-urchin, d^ Macrocheilnsfxisi- 
 formift: a gasteropod. e, Sphenophyllum: 
 an extinct tree. _/, Codacanthiis eUgaits: a 
 fish. *7, Presffvichia ant/ira.r: a crustacean. 
 A, Stigmaria : extinct plants, probably roots 
 of sigillarise. J, Cryptoga^noiis acrogen: an 
 arborescent fern, j^ Euryuof'is crenatus: a 
 fish, ky Pleurotomania carinata: agastero- 
 
 pod. I, Nautilus Konincl'ii: a mollusk. 
 m, Euomphaius pentangulatns: a gastcro- 
 pod. ?(, Avinculo-pecten: a bivalve mol- 
 lusk. 
 
 Triassio. — «, Sfcvll of lahyrinthodon : a 
 reptile, h, Microbites a)itiquus\ a mammal, 
 cVoltzia heteropliylla: an extinct plant. </, 
 I-ooi-pi-ints of Brontozoum : a reptile, f, 
 Tivniopterifi viitata : leaf of an extinct plant. 
 ,/", PaUvon iscus inaleopomvs : a fish. *?, Ecri- 
 n>ft! lilli/ormis: a crinoid, a sea-Uly. A, 
 Bidlamitella : a polyp, i, Plerophylhim JiC- 
 geri: portion of an extinct plant. 
 
 Jurassic and Cretaceous. — (7, Archfe- 
 optery.v : the first bird, with reptilian cliar- 
 acteristics. b. Orthoceras: a cephalopod. 
 c, Ammonites: a mollusk. rf, /i, », Leaves 
 from cretaceous trees: deciduous exogens. 
 e^ IchtkyosauTHS : a tish-like reptile. ./, 
 Ancyloceras macrnmnllus: a mollusk. g^ 
 Hesperornis regalia: a bird, i, Pterodac- 
 tylus: a bird-like reptile, y, Plesiosaurus: 
 a lizard-Mke reptile, k^ Ammonites Hum- 
 phrey siamis: a cephalopod. I, Toxocerus 
 bituberculatus: a molhisk. m, Beryx Lew- 
 esiensis: a fish. 0, Plants of the period: 
 fossil leaves. /». Cycas Zamia : a tree bc- 
 longiniT to a family which still has livinij 
 forms, y, Acrogen : an herbaceous fern. 
 
 r, Am^monites koplites: a mollusk. «, Palmr- 
 tree, t^ Oak. 
 
 Tertiary. — «, Megatherium: a gigantic 
 extinct mammal witli affinities to the sloth, 
 i, Mastodon : an extinct elephant-like mam- 
 mal with four tusks, c^ Iihinoccrotida: an 
 early extinct form of rhinoceros restored by 
 Packard, c?, Cotylopkora: an extinct Amer- 
 ican antelope. «, Mylodon : an extinct mam- 
 mal allied to the megatherium. /, Dino- 
 therium: an extinct mammal, the largest 
 that has ever lived, g^ Dinocerata : an ex- 
 tinct form combining the characteristics of 
 several existing families of mammals. A, 
 Lisfriodon : an extinct tapir, i. Xiphodon : 
 extinct mammal, light, and deer-like in 
 form, y, Dinoeeras: an animal belonging 
 to the order Dinoceratje. k^ Glypiodon : a 
 gigantic extinct armadillo. /, Annplnthe- 
 riujn : an extinct mammal, semi-aquatic in 
 its habits, like the hippopotamus. 
 
 Drift. — ff, Alee: moose. 6, Uhinoce- 
 rotida : extinct double-horned rhinoceros, 
 r, Dinornis: gigantic extinct bird. </, B. 
 Americarius: bison, e^ Homo: man. /^ O. 
 moschatus: musk-ox. j?, Equida: horse. 
 A, Rangifer: reindeer. »', Mammoth: ex- 
 tinct liairy elephant. j^Picotyles: peccary. 
 k^ Elephants 
 
INDEX. 
 
 Aconca{!:ua, 25. 
 
 At'ghims, 112. 
 
 Africa, relief of, 2S. 
 
 Air, composition and properties 
 of. 62. 
 
 Al;lsl^a, 132, 1.33. 
 
 Altai Mountains, 25, 
 
 Amazon, 25, 48. 
 
 American Continent, the, 22. 
 
 Andes, the, 24. 
 
 Animal life. 100. 
 
 Animal products, 106. 
 
 Antarctic Contment, 29, 55. 
 
 Antarctic icebergs, 85. 
 
 Anthropology, 107. 
 
 Anti-trade winds, 70. 
 
 Appalachian Mountain System, 24, 
 126. 
 
 Appalachian revolution, 123. 
 
 Ararat, 26. 
 
 Archaean Era, 11. 
 
 Arctic Ocean, 54. 
 
 Areas, comparative, of land and 
 water, 16. 
 
 Artesian wells, 42. 
 
 Arthropoda, 101. 
 
 Aryans, 114. 
 
 Asia, highlands of, 25. 
 
 Atlantic coast of North Amer- 
 ica, 22. 
 
 Atlantic currents, 59. 
 
 Atlantic Ocean, 53; plain, 126. 
 
 Atlanto-saurus, 14. 
 
 Atmosphere, the, 62 ; moisture 
 of, 76. 
 
 Atmospheric pressure, 62. 
 
 Atolls, 31. 
 
 Aurora, the, 80, 87. 
 
 Australasians, 107. 
 
 Australia, physical features of, 
 29. 
 
 Aztecs, 112. 
 
 Bacteria, 88. 
 Barometer, 62. 
 Barrens, 18. 
 Bars, 45. 
 Batrachia, 102. 
 Ben-Nevis, 27. 
 Bermudas, the, 31. 
 Beryl, 122. 
 Birds, 102. 
 Bison, the, 135. 
 Bores, 57. 
 Botany, 88. 
 Building-stones, 117. 
 Burmese, 109. 
 
 Calderas, 35. 
 
 Cambrian Age, 11. 
 
 Cameroons, 29. 
 
 Canons, 18; of the Colorado, 18, 
 
 131. 
 Carboniferous Age, 14. 
 Caribbean Sea, the, 60. 
 Caribou, the, 135. 
 Caspian Sea^ 28. 
 Cavern debru, 22. 
 Caves, 19, 22; evidence furnished 
 
 by, as to the ancient history of 
 
 man, 22. 
 Cevennes, the, 27. 
 Charleston earthquake, 41. 
 Chinese people, the, 109. 
 Cirrus, 78. 
 Clav, 116. 
 Clift-dwellcrs, 112. 
 Climate, 62-67 ; of the United 
 
 States, 131. 
 Climatic realms, 65. 
 C'loudsj 78, 79 ; formation of, 78 ; 
 
 classiiication of, 78 ; as protec- 
 
 ors, 79 ; motion of, 79 ; rain, 
 
 79. 
 Cloud-tints, 79. 
 Coal, 14, 117 ; in the United States, 
 
 137. 
 Ccelenterata, 100. 
 Constellations, 4. 
 Continents, 17. 
 Copper, 116 ; in the Dnited States, 
 
 138. 
 Coral islands, reefs, polyp, 30, 
 
 31. 
 Coral, varieties of, 30 ; history of, 
 
 30. 
 Cordillera, 18. 
 Co-tidal lines, 58. 
 Cotopa.xi, 34. 
 Crater Lake, 46. 
 Cretaeeouo Age, 14. 
 Crinoids, 14. 
 Cumulus, 79. 
 
 Currents, 59-61. 
 Cyclones, 71, 74, 75. 
 
 Dead Sea, the, 46. 
 
 Deltas, 45. 
 
 Deserts, 18. 
 
 Devonian Age, 14. 
 
 Dew, 77. 
 
 Dew-point, 76. 
 
 Diamond-fields, South African, 
 120 ; Brazilian, 121. 
 
 Diamonds, 120, 121 ; value of, 121. 
 
 Distances of the fi.\ed stars, 4. 
 
 Dovreficld Mountains, 27. 
 
 Downs, 17. 
 
 Drainage, of North America, 48 ; 
 of South America, 48 ; of tiira- 
 sia, 49 ; of Africa, 49 ; of Aus- 
 tralia, 49. 
 
 Dunes, mode of formation, and 
 economic uses of, 29. 
 
 Earth, size and form of, 4 ; com- 
 parison of, with other members 
 of solar system, 5 ; motions of, 
 6; history and present condition 
 of, 5 ; materials composing the, 
 10 ; temperature of, 32 ; eleva- 
 tion and depression of surtlice 
 of, 32. 
 
 Earthquake periods, 40. 
 
 Earthquakes, 37-41. 
 
 Eastern Continent, the, 25. 
 
 Echinoderraataj 101. 
 
 Elburz Mountams, 26. 
 
 Electricity, atmo.-iplierie, 86. 
 
 Elevation of earth's crust, 16. 
 
 Erosion, 16, 19. 
 
 Esquimaux, 110. 
 
 Etna, .33. 
 
 Eui'asia, 25; relief of, 26, 27; con- 
 tinental islands of, 28. 
 
 Europe, highlands of, 26. 
 
 Everest, Mount, 25, 27. 
 
 Falls oftheEhine, 44. 
 
 Faults, 10. 
 
 Faunal realms, 103. 
 
 f errcl's Law, 59, 69. 
 
 Fingal's Cave, 22. 
 
 Fishes, 101 ; age of, 14. 
 
 Fissures, 10. 
 
 Forest-covered plains, 18. 
 
 Forest regionsof the United States, 
 137. 
 
 Forestry, 98. 
 
 Fossil mammalia, 137. 
 
 Fossils, 11 ; found beneath the in- 
 crustations of caveni-iioors, 1i'2. 
 
 Frost, 77. 
 
 Game-laws, 102. 
 Ganges, the, 49. 
 Garden of the Gods, 127. 
 Gem-cutting, 122. 
 Gems, 120, 122; imitation, 122. 
 Geography, defined and classi- 
 fied, 3. 
 Geological agencies, 10. 
 Geology, defined^ 3 ; method of 
 
 studying, practically e.xplained, 
 
 11 ; economic, 115. 
 Geysers, 37 ; of the United States, 
 
 131. 
 Glaciers, 83-85. 
 Gobi, Desert of, 25. 
 Gold, 115 ; in the United States, 
 
 138. 
 Gold-fields of North America, 
 
 115; of Africa, 115. 
 Grampian Plills, 27. 
 Granite, 10, 116. 
 Great Salt Lake. 47. 
 Great Valley of North America, 
 
 24, 123. 
 Great Valley of South America, 25. 
 Grotto of Adelsberg, 22. 
 Grotto del Cane, 36. 
 Gulf of Mexico, the, 53. 
 Gulf Stream, origin, temperature, 
 
 and depth of, 60. 
 
 Hail, 82. 
 
 Hailstones, forms of, 82 ; destruc- 
 tive force of, 82. 
 
 Hailstorms, 83. 
 
 Hawaii, 35. 
 
 Hecla, Mount, 33, 35. 
 
 Himalayas, 25. 
 
 Human family, the, 107. 
 
 Humidity, absolute and relative, 
 76. 
 
 Hyperboreans, 110. 
 
 Icebergs, 85 ; size and appearance 
 of, 85; carrying-power of, 85. 
 
 Ice Period, 15. 
 
 Ichthyornis, 14. 
 
 Ichthyosaurus, 14. 
 
 Igneous rocks, 10. 
 
 Illimani, 25. 
 
 Indian Ocean, 54. 
 
 Indians, American, 111. 
 
 Iran, plateau of, 26. 
 
 Iron, 116; in the United States, 
 138. 
 
 Islands, oceanic, 30 ; coral, 30. 
 
 Isobars, 68. 
 
 Isoclinal Lines, 8. 
 
 I^ogonie Lines, 7. 
 
 Isotherms, 64. 
 
 Japan Current, 61. 
 Japanese, 110. 
 Jupiter, 5. 
 Jura, the, 27. 
 Jurassic System, 14. 
 
 Kilauea, 35. 
 
 Kiliman.iaro, Mount, 29. 
 Kimberley mines, 120. 
 Kongo Elver, 49. 
 Krakatoa, 34. 
 Kuen-Lun Mountains, 25. 
 
 Lakes, origin, size, depth of, 46 ; 
 of North America, 46 ; of Soutli 
 America, 47 ; of Europe, 47 ; of 
 Asia, 47 ; of Africa, 47 ; of Aus- 
 tralia, 48. 
 
 Lake Baikal, 46. 
 
 Lake Solfatara, 36. 
 
 Land, distribution of, north and 
 south of the Equator, 17. 
 
 Land and sea breezes, 70. 
 
 Land and water areas, 16. 
 
 Lava, composition and character- 
 istics of, 35. 
 
 Lead, 116; in the United States, 
 138. 
 
 Lena Eiver, 45. 
 
 Lipari Islands, 35. 
 
 Llanos, 17, 18. 
 
 Looming, 87. 
 
 Lost rivers, 22. 
 
 Lucerne, lake of, 47. 
 
 Luray Cavern, 19. 
 
 Madagascar, 29. 
 
 Magnetic elements, 7 ; variation 
 
 of, 8. 
 Magnetic induction, 6. 
 Magnetic meridian, 6. 
 Magnetic storms, 9. 
 Magnetism, 6; cause of the earth's, 
 
 9. 
 Malayo-Polvnesians, 111. 
 Mammalia, 102, 103. 
 Mammoth, the, 15. 
 Mammoth Cave, 19. 
 Man, 107 ; age of, 15 ; degraded 
 
 state of, on coral islands, 31. 
 Manatee, 134. 
 Mariner's compass, 7; invention 
 
 and history of, 7. 
 Mars, 5. 
 Mass, defined, 5 : of sun, earth, 
 
 and planets, compared, 6. 
 Mauna Loa, 35. 
 Melanesians, 108. 
 Mercator's Projection, 9. 
 Mercury, 116. 
 Mesa, 17. 
 Mesozoic Era, 14. 
 Metals, 115. 
 
 Metamorphic rocks, 10. 
 Meteoric bodies, 5. 
 Mineral products, 115. 
 Mineral waters of the United 
 
 States, 43 ; of Europe, 43. 
 Mirage, 87. 
 Mississippi, 136. 
 Mollusca, 101. 
 Monsoons, 71. 
 Mont Blanc, 27. 
 Moon, the, 5. 
 Moose, the, 135. 
 Moraines, 84. 
 Morteratsch Glacier, 83. 
 Motion of glaciers, 84. 
 Mound-builders, 111. 
 Mountain-passes, 19. 
 Mountain-streams, 19, 43. 
 Mountains, mountain-i-anges. 18 ; 
 
 height of, 19 ; vegetation on, 19. 
 Mount St. Elias, 23. 
 Mud-volcanoes, 36. 
 
 Nebulae, 4, 5. 
 Nebular Hypothesis, 4. 
 Negritoes, 107. 
 Negroes, 107. 
 Neozoic Era, 15. 
 Nevada de Sorata, 25. 
 Niacrara, 44. 
 Nickel, 116. 
 Nile, the, 49. 
 Nimbus, 79. 
 
 North .America, coast of, 22 ; relief 
 of, 23; continental islands of, 24. 
 Northers, 71. 
 
 Ocean, the Atlantic, 53 ; the Pa- 
 cific, 53 ; the Polar, 54 ; Ant- 
 arctic, 55 ; currents of the, 59. 
 
 Ocean-currents, 59. 
 
 Oceanictvalleys, 17. 
 
 Oscillations of the earth's surface 
 explained, 32. 
 
 Pacific coast of North America, 22. 
 
 Pacific currents, 61. 
 
 Pacific Ocean, 17, 53. 
 
 Paleontology, defined, 11. 
 
 Palteozoic £ra, 11. 
 
 Pampas, 18. 
 
 Pearls, 122. 
 
 Peccaries, 135. 
 
 Peruvian Current, 61. 
 
 Petroleum, 117; in the United 
 States, 138. 
 
 Physics of the earth' s crust, 32-41 . 
 
 Physiography, relief of the earth, 
 16. 
 
 Plains, 17. 
 
 Planetoids, 4. 
 
 Planets, 4. 
 
 Plant-life, 88-98. 
 
 Plant products, 96. 
 
 Plants, structure of, 88 ; classifica- 
 tion of, 88 : organs of, 89 ; geo- 
 graphical distribution of, 91. 
 
 Plateaus, 18. 
 
 Platinum, 116. 
 
 Plesiosauru-s, 14. 
 
 Polar winds, 70. 
 
 Popocatepetl, 34. 
 
 Porifera, TOO. 
 
 Prairies, 18. 
 
 Precious stones, 120 ; in the United 
 States, 138. 
 
 Precipitation, 77. 
 
 Primitive man, 15. 
 
 Protozoa, 100. 
 
 Pterodactyl, 15. 
 
 Puma, the, 136. 
 
 Punjab, 49. 
 
 Pyrenees, the, 27. 
 
 Quaternary Age, 15. 
 
 Eain, 79 ; cause of, 79 ; effect of, 
 on climate, 79. 
 
 Eain-clouds, 79. 
 
 Eainfall, 80-82; effect of vegeta- 
 tion on, 80; excessive and de- 
 ficient, 80 ; general laws of, 81 ; 
 measurement of, 81 ; mean an- 
 nual, 82. 
 
 Eapids, 44. 
 
 Eelief, defined, 16. 
 
 Eeptiles, age of, 14. 
 
 Reptilia, 102. 
 
 Eivei's, 43 ; origin and velocity of, 
 43 ; transporting power of, 44. 
 
 Eiviera earthquake, 41. 
 
 Eocks, igneous, sedimentary , meta- 
 morphic, 10; fossiliferous, 11. 
 
 Eocky Mountains, 23, 124. 
 
 Eode'nts, 134. 
 
 Eubies, 121. 
 
 Salt, 117, l'38. 
 
 Sapphire, 121. 
 
 Sargasso Sea, 60. 
 
 Satellites, 4. 
 
 Saturn, 5. 
 
 Sea-bottom, configuration of, 53. 
 
 Sea-level, moan, explained, 19. 
 
 Seals, 136. 
 
 Seasons, change of, explained, 6. 
 
 Sea-water composition of, 52 ; 
 color of, 52; phosphorescence 
 of, 62 ; density and pressure of, 
 52 ; temperature of, 52. 
 
 Sedimentary rocks, 10. 
 
 Semitic race, 112. 
 
 Siamese, 109. 
 
 Sierra, 18. 
 
 Silurian Ages, 14. 
 
 Silver, 116." 
 
 Silvas, 17, 25. 
 
 Sioux, 112. 
 
 Sleet, formation of, 82. 
 
 Snow 82 ; red, phenomenon of, 
 
 explained, 82. 
 Snowdon, Mount, 27. 
 Snow-fallj at the summits of lofty 
 
 mountams, 83. 
 Snow- line, 19, S3 ; descent of, with 
 
 increase of latitude, 83. 
 Soil, 10; mode of production of, 
 
 by disintegration of rocks, 10, 
 
 11. 
 Solar energy, 63. 
 
 Solar system, 4 ; growth of, ac- 
 cording to nebular hypothesis, 4. 
 South America, relief of, 24j 25. 
 Springs, mineral and intermittent, 
 
 43. 
 Stalactites, 22. 
 Stalagmites, 22. 
 Stars, 4. 
 
 Staubach, the, 44. 
 Steppes, 18. 
 
 St. Lawrence Eiver, 127. 
 Storms, 71. 
 Strata, 10. 
 Stratus, 78. 
 Stromboli, 33. 
 
 Sun, as a star, 4; volume, etc., 5. 
 Swamps, 18. 
 
 Table-land, 17. 
 
 Tasinanians, 108. 
 
 Taurus Eange, 26. 
 
 Temperature of the earth's crust, 
 
 32 ; of the sea, 52. 
 Tertiary -Age, 15. 
 Teutonic race, 112. 
 Thian-Shan Mountains, 25. 
 Tides, 56-58. 
 Tiffany diamond, 121. 
 Timber-line, 19. 
 Tin, 116, 138. 
 Titieaca, 47. 
 Tornadoes, 75. 
 Trade-winds, 70. 
 Triassie Age, 14. 
 Trilobites, 11. 
 Tundras, 18, 133. 
 
 United States, physical features 
 of, 23, 124; geological history 
 of, 123; surface structure, 124; 
 Great Valley of, 126 ; coast-line 
 of, 127; river-systems of, 127; 
 climate of, 131 ; rainfall of, 131 ; 
 mammals of, 134 ; vegetation of, 
 137 ; minerals of, 137. 
 
 Upas Valley, 36. 
 
 Ural Eange, 27, 28. 
 
 Valley of the Amazon, 25. 
 
 Valleys. 17. 
 
 Vapor, 76. 
 
 Vegetable products of the United 
 States, 137. 
 
 Veins, 10. 
 
 Vesuvius, S3. 
 
 Victoria diamond, 121. 
 
 Victoria Falls, 45. 
 
 Victoria Nyanza, 47. 
 
 Volcanic cones, 35. 
 
 Volcanic pho!iomena, 32-36. 
 
 Volcano, 35. 
 
 Volcanoes, number of, 36 ; prox- 
 imity to the sea, 36. 
 
 Volume, defined, 5 ; of sun, earth, 
 and planets, compared, 5. 
 
 Walruses, 186.^ 
 
 Water, properties of, 42. 
 
 Waterfalls, 44. 
 
 Water-gaps, 19. 
 
 Water-spouts, 76. 
 
 Waters, inland, 42 ; ocean, 52. 
 
 Waves, 56. 
 
 Weather observations, 82. 
 
 Wells, artesian, 42. 
 
 Western Plateau of North Ameri- 
 ca, 23 ; climate of, 23 ; mount- 
 ain-ranges of, 23, 24. 
 
 Whirlpools, 58. 
 
 Winds, 68 ; constant and periodi- 
 cal, 70. 
 
 Wind-zones, 70. 
 
 Yablonoi Mountains, 25. 
 Yellowstone National Park, ISlo 
 Yukon Kiver, 133. 
 
 Zinc, 116, 138. 
 Zool')gy, 100, 
 

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