A COURSE OF INSTRUCTION IN ORDNANCE AND GUNNERY; PREPARED FOR THE USE OF THE C ADE T S OF THE UNITED STATES MILITARY ACADEMY. BY BREVET-COL. J. G. BENTON, MAJOR ORDNANCE DEPT., LATE INSTRUCTOR OF ORDNANCE AND SCIENCE OF GUNNERY, MILITARY ACADEMY, WEST POINT. THIRD EDITION, REVISED AND ENLARGED. NEW YORK: D. VAN NOSTRAND, 192 BROADWAY. 1867. Entered according to Act of Congress, in the year 1867, BY D. VAN NOSTRAND, In the Clerk's Office of the District Court of the United States for the Southern District of New York. PREFACE TO THIRD EDITION. IN Part I. of this work, the author has endeavored to describe briefly the principal articles of our Army Ordnance Jcfteritel, and to state the general principles of their construction and operation. It is thought that Part II. contains the data and formula necessary to determine with practical accuracy the movement and effects of rifle as well as smooth-bore projectiles. The Appendix contains short descriptions of some of the most noted modern cannon and projectiles, and a tabular statement of some of the principal experiments made in England with armor plates. The works which have been principally consulted, and in many instances quoted ver6batirn, are PIOBERT'S Cours d'Artillerie, Ordncance Iancmtal, Reports on Powder, Cannon, Metals, and Small-arms, &c., by officers of the Ordnance Department, U. S. A., and HOLLEY'S Ordnance and Armor. CONTENTS. CHAPTER I. PAGE. GUNPOWDER...................................................... 7 CHAPTER II. PROJECTILES 71 CHAPTER III. CANNON...1.............................. 104 CHAPTER IV. ARTILLERY CARRIAGES. 212 CHAPTER V. MACHINES AND IMPLEMENTS................... 248 CHAPTER VI. SMALL-ARMS.................................................. 270 CHAPTER VII. PYROTECHNY..................................................... 342 CHAPTER VIII. SCIENCE OF GUNNERY............. 382 CHAPTER IX. LOADING, POINTING AND DISCHARGING FIRE-ARMS...................... 435? CHAPTER X. DIFFERENT KINDS OF FIRES.......................................... 450 CHAPTER XI. EFFECTS OF PROJECTILES.............................................. 471 CHAPTER XII. EMPLOYMENT OF ARTILLERY...................... 488 CHAPTER XIII.. TABLES OF MULTIPLIERS.............................................. 505 TABLES OF FIRE.................................................... 516 APPENDIX........................................ 525 INDEX.................................................... 537 ORDNANCE AND GUNNERY. PART I. CHAPTER I. GUNPOWDER. 1. General theory. Gunpowder and the compositions of pyrotechny are the means used, in modern warfare, to propel projectiles, explode mines, destroy ships and buildings, and furnish light and. signals for the operations of an army at night. They are simply mechanical mixtures of substances which give out light, heat, and gas in their combustion, or chemical union with each other. The two classes of substances generally used for these purposes are the?nitrate8 and chlorates on one hand, and clharcoal, 8ulphur, antimony, &;c., on the other. The former class contains a large amount of oxygen, which is a strong supporter of combustion; and the latter embraces those substances which have a powerful affinity for it. EScplosion is a phenomenon arising from the sudden enlargement of the volume of a body, as in the case of combustion, when a solid body is rapidly converted into one of vapor or gas. If this change of state be 8 GUNPOWDER. accompanied by the development of a large amount of heat, the explosive effect will be very much increased. Gunp)owder is an explosive substance, formed by the mechanical mixture of nitrate of potassa, sulphur, and chcarcoal. The parts performed by these ingredients in the explosion will be best understood by an examination of the following table: COMPOSITION OF GUNPOWDER. BEFORE COMBUSTION. AFTER COMBUSTION. 3 parts of carbon, 3 carbon, 3 carbonic acid (gad). 6 oxygen, 1 part of nitrate of potassa, 1 nitrogen, 1 nitrogen (gas). 1 part of sulphur, 1 sulphur, A gunpowder can be made of nitrate of potassa and charcoal alone; but it is not so strong as when sulphur is present; besides, the substance of the grain is friable, has considerable affinity for moisture, and rapidly fouls the arms in which it is used. Theoretically, sulphur does not contribute directly to the explosive force of gunpowder by furnishing materials for gas; but,by uniting with the potassium, it affords a large amount of heat, and prevents the carbonic acid from uniting with the potassa and forming a solid compound-the carbonate of potassa. It is to the heat and carbonic acid thus formed that gunpowder mainly owes its explosive force. The strength of gunpowder, or amount of work which a certain quantity is capable of performing in a given time, depends on the mass of the powder and the velocity with which its gaseous particles are evolved. SALTPETRE. 9 This velocity of evolution of the gaseous particles, or "quickness," depends on the purity, proportion, and incorporation of the ingredients, and on the size, form, and density of the grains. These will be discussed in the following pages, under the heads of iaterias, Fab.rication, 3fechanical Effects, and Chemical Properties of gunpowder. MATERIALS. SALTPETRE. 2. Description. Saltpetre, nitre, or nitrate of potassa, is composed of 53.45 of nitric acid, and 46.55 of potas. sa, or IO+_+iO,. It crystallizes in colorless six-sided prisms; has a cooling, saline, and slightly bitter taste, and defiagrates with more violence than any other nitrate when thrown on burning charcoal. It is anhydrous; but its crystals often contain water mechanically confined. It is not deliquescent in common air (a very important quality in an ingredient of gunpowder), but is so in an atmosphere nearly saturated with moisture. It is insoluble in the oils and pure alcohol. It Is decomposed when strongly heated, and oxygen is evolved at first; finally nitrogen is given off, and per. oxyde of potassium remains. When heated with combustible materials, nitre is completely deprived of its oxygen; it is consequently much used as an oxydizing agent. This is the part which it plays in gunpowder. The solubility of nitre increases rapidly with the temrn. perature. 100 parts of water at 320 dissolve 13.32 of nitre. " " " 64.4~ " 29.00 " " " " 113~ " 74.00 " re tr'C 2120 cc 246.15 10 GUNPOWDER. Hence, a hot saturated solution, on cooling, deposits the greater portion of the salt which had dissolved. 3. Sources. Nitrate of potassa, in connection with more or less of the nitrates of lime and magnesia, is obtained from several sources, among which may be enumerated calcareous caves, certain soils in warm climates, artificial nitre beds, and the mortar of stables or other buildings long occupied by animals, in which cases it generally occurs as an efflorescence. It is also found in the tobacco, sunflower, beet-root, cornstalk, and other plants. The caves occurring in certain porous limestones are often found to contain large quantities of the nitrates of lime, potassa, and magnesia, deposited in the loose materials at the bottom, efflorescing from the sides, or even contained in the pores of the rock itself. Many of the limestone caves in Kentucky, Virginia, Tennessee, &c., abound in nitrates. In Madison county, Kentucky, there is a cave 1,936 feet long by 40 wide, which contains the nitrates of potassa and lime, mingled with the earthy matter at the bottom. One bushel of the earth yields, by double decomposition with carbonate of potassa, from three to ten pounds of nitre. The greater part of the nitre used in England, and this country, is derived from the soil in various parts of the East Indies. It occurs in the same manner in various warm countries, as Egypt, Spain, &c. In the vicinity of Monclova, Mexico, it occurs in veins, or mines, in a state of great purity. It appears to be generated spontaneously at the depth where the soil retains its moisture; and when dissolved by rains, the subsequent evaporation, by capillary at SOURCES OF NITRE. 1 t traction, causes it to rise to the surface, where it is deposited as a crust. To obtain nitre fi6om this source, the earth is removed to a certain depth, and treated with water, which dissolves the soluble salts. The solution is then transferred to large reservoirs, when it soon evaporates by solar heat, and deposits large crystals of nitre. This is known in commerce as rouyh, or crude aZtpetre. The mother waters are rejected; but as they contain a large quantity of the nitrates of lime and magnesia, they might still afford some nitre if they were mixed with salts of potassa. In the north of Europe, where nitre does not occur as a natural product, various artificial processes have long been employed to obtain it; and similar methods were much used in France during the Revolution, when that country could not be supplied from Spain and other countries. The nitre-beds were mostly used. Xitre-beds. These were made by placing loosely on a floor of wood or clay, a layer, of three or four feet thick, of a mixture of earth, calcareous matter-such as marls, calcareous sands, mortar from stables, &c., and various animal products-such as blood, urine, stable manure, &c. Vegetable matter was found to be useful, probably furnishing potassa. The whole was placed under a shed, and occasionally moistened with additional.quantities of blood or urine, and in about two years it was fit for lixiviation. In Prussia, the materials are placed in parallel wcals about seven feet high, and three or four feet thick, which arrangement is found to be more convenient, and to occupy less space than the beds. 12 GUNPOWDER.-NITRE..ifortar exposed to decomposing animal matter, in moist, warm places, becomes considerably charged with nitrates. In consequence, the mortar in old stables is often found to be rich in nitrates, and may be used to obtain nitre directly, or it may be advantageously mixed with the materials for nitre-beds. The lye of nitrified substances contains nitrate of potassa, but especially nitrates of lime and magnesia, and also chlorides of sodium and calcium. The nitrates of lime and magnesia may be converted into nitrate of potassa by means of the carbonate of potassa; but on account of the increased value of this substance, the process now generally adopted is as follows, viz.: first, the nitrates of lime and magnesia are converted into the nitrate of soda, by means of the sulphate of soda, and then by the chloride of potassium, the nitrate of soda is converted into the nitrate of potassa. The nitrate of potassa thus obtained, like that obtained from the soils of warmer climates, is called rough esaltpetre, and contains from 15 to 25 per cent. of foreign matter, principally chlorides of sodium and potassium. These are separated by the process of refining. 4. Refining. The refining of nitr'e is founded on its rapidly-increasing solubility with elevation of temperature, while the solubility of the chlorides of sodium and potassium is nearly uniform. (For the details of this process see Ordnance Manual.) If, after nitre has been refined, it be desired to preserve it for future use, it is fused in iron pots, and cast into cakes weighing about seventy pounds. This method has the advantage of reducing its volume, and expelling the water of crystallization; but it requires a little TEST OF PURE SALTPETRE. 13 more work to pulverize it afterward in making gunpowder. As the United States are in a great measure dependent on the East Indies for this important material of,war, it has been the policy of the government to purchase yearly a certain quantity of rough saltpetre, refine and fuse it, and store it away in the arsenals for future use. The quantity now on hand in the arsenals amounts to several millions of pounds. 5. Tests. The test of rough saltpetre is founded on the fact that a solution of nitrate of potassa, saturated at a certain temperature, may be left in contact with an additional quantity of saltpetre at the same temperature, without sensibly dissolving any of it; while under the same circumstances it can dissolve sea salt, and many other soluble salts. To a pound of rough saltpetre add a pint of water, saturated with pure saltpetre; stir the mixture for ten minutes with a glass rod, and decant the liquor on a filter; wash the saltpetre a second time in the same manner, with half a pint of the saturated solution, and pour'the whole on the filter; let it drain, and then dry it perfectly by placing it first on a bed of some absorbent matter, such as ashes or lime, and then by evaporation in a glass vessel over a gentle fire. The saturated solution having taken up only the foreign salts, what remains on the filter (allowing two per cent. for earthy matter and the saltpetre left by the saturated water), is the quantity of pure saltpetre contained in the pound of rough. As the changes of temperature during the operation may affect the quantity of pure saltpetre remaining on the filter, it is proper to perform a corre 14 GUNPOWDER.-CHLORATE OF POTASSA. sponding operation at the same time and under the same circumstances, on a like quantity of pure saltpetre; the gain or loss thus ascertained will show the correction to be made in the former result. eest of pure 8altpetre. For powder, saltpetre should not contain more than 1-3000th of chlorides. To test this, dissolve 200 grains of saltpetre in the least possible quantity (say 1,000 grains) of distilled water; pour on it 20 grains of a solution of nitrate of silver, containing 10 grains of the nitrate to 1,032 grains of water, that being the quantity required to decompose 200-3000ths of a grain of muriate of soda; filter the liquid and divide it into two portions; to one portion add a few drops of the solution of the nitrate of silver; if it remains clear, the saltpetre does not contain more than 1-3000th of muriate of soda; to the other portion add a small portion of the solution of the muriate of soda; if it becomes clouded, the saltpetre contains less than 1-3000th. By using the test liquor in very small quantities, the exact proportion of muriate of soda may be ascertained. At the refinery of Paris it does not exceed 1-18,000th of the saltpetre; and this degree of purity is attained also at the refinery of Messrs. Dupont. Saltpetre for the best sporting powder is refined a second time, and contains not miore than 1-60,000th part of chlorides. 6. Chlorate of Potassa. Other oxydizing substances, such as the chlorate of potassa and nitrate of soda, may be used in the manufacture of gunpowder; but for this purpose, they are inferior to the nitrate of potassa. The chlorate of potassa is a substance which parts with its oxygen easily, and makes a powder, which has been -NATURE OF CHARCOAL. 15 found by experience, to give at least double the range with the mortar eprouvette, of that made with nitrate of potassa, but from its great quickness, resembles the fulminates in its destructive effects on the gun.. Besides, it is more costly than hitrate of potassa, renders the powder liable tQ explode by slight causes, and gives a residue which rapidly corrodes iron. Its use in the laboratory is chiefly confined to the preparation of colored fires and cannon primers. The nitrate of sodac is found as an extensive deposit in the soils of some portions of Peru and northern Mexico. It is cheaper than nitrate of potassa, and for the same weight affords a greater amount of nitric acid, or oxygen. Its affinity for moisture constitutes a serious objection to its use in the manufacture of a gunpowder for war purposes, or one that is to be preserved for any length, of time. The nitrate of soda may be used in obtaining the nitrate of potassa by decomposing it with carbonate of potassa-the potash of commerce. CHARCOAL. 7. Nature of charcoal. Charcoal is the result of the incomplete combustion or distillation of wood. Its composition and properties vary with the nature of the wood, and mode of distillation employed. Charcoal obtained from light wood is the best for gunpowder, as it is more combustible and easy to pulverize, and contains less earthy matters. Willow and poplar are used for this purpose in the United States, and the black alder in Europe. The wrood must be sound, and should not be more than three 16 GUNPOWDER.-CHARCOAL. or four years old, and about one inch in diameter; branches larger than this should be split up. It is cut in the spring, when the sap runs freely, and is immediately stripped of its bark. The smaller branches are used for fine sporting powder. The operation of charring may be performed in pits, but the method now almost universally used in making charcoal for gunpowder is that of distillation. For -this purpose the wood is placed in an iron vessel, generally of a cylindrical form, to which a cover is luted; an opening with a pipe is made to conduct off the gaseous products, and the wood is thus exposed to the heat of a furnace. The progress of distillation is judged of by the color of the flame and smoke, and sometimes by tet-s.ticks, which are introduced through tubes prepared for the purpose. 8. Properties. The charcoal thus obtained should retain a certain degree of elasticity, and should have a brown color, the wood not being entirely decomposed; it retains the fibrous appearance of the wood, and the fracture is iridescent. As it readily absorbs 1-20th of its weight of moisture, which diminishes its inflammability, it should be made only in proportion as it is required for use. Wood generally contains 52 per cent. of carbon, but distillation furnishes not more than 30 to 40 per cent. of charcoal. The specifc gravity of charcoal triturated under heavy rollers, is about 1.380; but in sticks, as it comes from the charring cylinders, it rarely exceeds.300. The properties of charcoal vary much with the ternmperature employed in the preparation. If wood be merely heated until it ceases to give off vapor, a true ACCIDENTS. 1 charcoal is obtained; but by raising the temperature to redness or whiteness, its properties will be much changed, as is shown in the following table: When not heated to Heated to redness. Heated to whiteness. rednes3. For electricity, Non-conductor. Good conductor. Excellent conductor. heat. Very bad conductor. Good conductor. Excellent conductor. Combustibility, Easy. Less easy. Difficult. If sufficient heat be applied to drive off all the vola. tile matters in six hours, a black charcoal, containing from 28 to 33 per cent. of carbon, will be obtained. If the heat be reduced so as to prolong the distillation to twelve hours, the charcoal will have a yellowish brown color, and will contain from 38 to 40 per cent. of carbon. Charcoal inflames at about 460~ Fahrenheit. A black coal strongly calcined takes fire quickly, but is easily extinguished. A brown charcoal takes fire slowly, but burns strongly and rapidly. As it is desirable to have charcoal for gunpowder very combustible,. it must therefore be prepared at a low temperature, and must be light. In distillation, the heat is kept below redness. 9. Accidents. When recently prepared charcoal is pulverized and laid in heaps, it is liable to absorb oxygen with such rapidity as to cause spontaneous combustion. This has been the cause of serious accidents at powder-mills; and hence it is important not to pulverize charcoal until it has been exposed to the air for several dclays. In Prussian powder-mills, pulverized 0 18 GUNPOWDER. -CHARCOAL. charcoal is kept in a fireproof room, in iron vessels, as a precaution against accidents. When charcoal has not absorbed moisture, and is mixed with oxydizing substances, it may be inflamed by violent shocks, or by friction. This is the principal cause of the accidents which occur in the preparation of explosive mixtures which contain charcoal. 10. Combustibility. For the purpose of comparing the comn:u6tibility of charcoals made of different materials, a certain quantity of each is thoroughly mixed with nitre, in the proportion of 1 part of the former to 5 of the latter, and driven compactly into an iron tube about.25 inches in diameter; the weight and length of the filled tube are taken, and the duration of the combustion is ascertained by a pendulum or chronometer. The length of composition burned in a second of time is called the velocity of combustion, and is taken as the measure of the combustibility of that particular kind of charcoal. The amount of residue is ascertained by subtracting the weight of the tube and residue after burning from that of the filled tube before burning, and again subtracting this difference from the weight of the composition originally in the tube. The velocity of combustion is independent of the diameter of the tube and of the material of which it is made; but it varies slightly with the pressure used in driving the composition, and very much with the degree of trituration of the materials. The following tables contain some of the results thus obtained, viz.: COMBUSTIBILITY OF CHARCOAL. 19 60 parts of nitre and 12 of charcoal. Velocity of com- Percentage of Black Charcoals. bustion. residue. Charcoal of Hemp,...31 inch. 16.6 "4 Grape Vine,...26 " 27.7 6" Pine,....18 " 41.6 " ]Black Alder,...16 " 33.3 6" Spindle Tree,..15 " 37.5 " Hazel,...13 ".41.6 " - Chestnut,...14 " 50.0 6" Walnut,...11 " 45.8 4" Coke...06 " 62.5 " Sulgar,....04 " 66.6 Charcoal made by distilling Black Alder, and conducted so as to give, For 100 p'ts wood, 40 p'ts charcoal,.14 inch. 39.0 "6 " c 30.16 " 37.0 6 44" 25 ".15 " 33.3 4 " 15 4.12 4 35.0 The following table shows the influence of trituration and proportion of ingredients: Charcoal made of Hemp. Charcoal made of Pine. Parts of 6 hours' trituration 4 hours' trituration. t6itutio; trthours 4 hourso Mixture, charcoal to 60 of Per ct. of Pr. ct. of V elocity. residue. Velocity. residue.l Velocity. eocit - 8 —.10 in. 58.0.08 in. 55.0.09 in..07 in. 10.12 45.0.10 43.0.15.09 12.31 16.6.17 26.0.18.12 15..39 13.0.27 17.0.35.20 4 20.56 12.0.39.27 11 1 30.65 11.0.59.53 20 GUNPOWDER.-SULPHUR. SULPHUR. 11. Properties. Pure sulphur is of a citron-yellow color, and shining fracture; it crackles when pressed in the hand. The specific gravity of native sulphur is 2.033; that of sulphur refined by sublimation 1.900; its specific gravity is diminished by trituration. When heated, it melts at 226~ into a thin, amber-colored liquid; if the temperature be then raised to about 400~ it becomes dark and thick; but if heated still further, up to 800~, its boiling point, it becomes again thin and limpid. It begins to pass off in vapor at 1150, and if heated rapidly, inflames at 370~. It is insoluble in water, but soluble in oils and slightly so in alcohol. Sulphur is generally found in great quantities in the neighborhood of volcanoes; it may also be obtained from metallic ores (pyrites) and other sources. Most of that used in the United States comes from Sicily through the French refineries. Crude sulphur, as extracted by the first sublimation from the ore, contains about 8 per cent. of earthy matter. It is purified by. a second sublimation, front which it is collected in the form of powder, called the fowve's of sulphnr; or, it is melted and run into moulds, making roll 6rirnstone. It may be also refined, but not so thQroughly, by being simply melted and skimmed. Pure sulphur is entirely consumed in combustion; and its purity is thus easily tested by burning about 100 grains in a glass vessel; the residue should not exceed a small fraction of a grain. MANUFACTURE. 21 MANUFACTURE OF GUNPOWDER. 12. Proportions of ingredients. Nitre. Charcoal. Sulphur By the atomic theory,.. 4.64 13.51 11.85 (NO4-0+KO) + 3C + S. In the United States: For military service,... 76.00 14.00 10.00 For blasting and mining,. 62.00 18.00 20.00 The proportions of the ingredients of the earliest gunpowder known, differ but slightly from those now in use; and these, it will be seen, nearly agree with those called for by the theory of combining equivalents. For the general purposes of artillery, slight variations in the proportions of the ingredients for powder are not found to affect its strength; but for blasting or mining purposes, a slower powder is found to answer nearly as well as a quick one, consequently the proportion of nitre is reduced much below that of gunpowder. Blasting powder is thus made cheap; but as it leaves a large amount of residuum, it cannot be advantageously used an fire-arms. 13. Operations. The several operations of fabricating gunpowder are: 1st. Pulverizinj; which consists in reducing the ingredients to finely divided dust. 2d. Incorporating; which consists in bringing the particles of this dust into such intimate contact that each particle of powder shall be composed of one of each of the ingredients. 3d. C6ompressing; which gives strength and density to the substance of the powder, by converting the in 22 GUNPOWDER.-MANUFACTURE. corporated mixture into a cake which will not crumble in transportation. 4th. Graining; which breaks up the cake into small fragments or grains, and increases the surface of combustion. 5th. Glazing; which hardens the surface, to protect it from the action of moisture, and rounds the sharp angles of the grains to prevent the formation of dust in transportation. 6th. Drying; which frees the powder from the moisture introduced in certain operations of the fabrication. 7th. Dasting; which frees it from the dust, which would otherwise fill up the interstices and retard the inflammation of the charge. The proportions of the ingredients, as well as the art of making gunpowder, vary in different countries, and even among the different manufactories of the same country. The variations in the proportions are slight, however, and the differences in the modes of manufacture are principally confined to the more important operations of pulverizing, mixing, and compressing the comnposition. For French military powder, these operations are performed in the "pounding-mill," or a series of mortars and -pestles. In Prussia the composition is pressed into cake by passing it between two heavy rol. l'ers, by means of an endless band of cloth, which receives the dust from a hopper. In England these operations are performed by the "rolling-barrel," "cylinder-mill," and "press." The superior strength and excellent preservative qualities of the English powder MANUFACTURE. 23 have led to the adoption of this mode of manufacture in the United States. 14. Processes of manufacture.* The buildings in which the different operations are carried on are separated from each other, and protected by trees or traverses as far as practicable. Pulverizing. The saltpetre is usually pulverized sufficiently when it comes from the refinery. The charcoal is placed in large cast-iron barrels Gith twice its weight of zinc balls. The barrel has several ledges on the interior, and is made to revolve from 20 to 25 times in a minute. It is pulverized in 2 or 3 hours. The sulphur is placed in barrels made of thick leather stretched over a wooden frame, with twice its weight of zinc balls from.3 to.5 inches in diameter, and the barrel made to revolve about 20 times per minute. It takes one hour to pulverize the sulphur. Ihbcoiporatirng. The ingredients having been weighed out in the proportions above given, the charcoal and sulphur are put together in a rolling-barrel similar to that in which the sulphur is pulverized, and rolled for one hour. The saltpetre is then added, and rolled for three hours longer. In some mills this operation is omitted. It is now taken to the cylinder, or rollingjmill. This consists of two cast-iron cylinders rolling round a horizontal axis in a circular trough of about 4 feet diamneter, with a cast-iron bottom. The cylinders are 6 feet in diameter, 18 inches thick on the face, and weigh about 8 tons each. They are followed by a wooden scraper, which keeps the composition in the centre of the trough. * Vide Ordnance Manual 24 GUNPOWDER.-MANUFACTURE. A charge of 75 lbs. in some mills, and 150 lbs. in others, is then spread in the trough of the rolling-mill, and moistened with 2 to 3 per cent. of water, according to the hygrometric state of the atmosphere. It is rolled slowly at first, and afterward from 8 to 10 revolutions of the roller per minute, for 1 hour for 50 lbs., and 3 hours for 150 lbs. of composition. A little water is added, as the process advances, if the composition gets very dry-which is judged of by its color. When the materials are thoroughly incorporated, the cake is of a uniform, lively, grayish, dark color. In this state it is called mill-cake. The quality of the powder depends much on the thorough incorporation of the materials, and burns more rapidly as this operation is more thoroughly performed. The mill-cake is next taken to the press-house, to be pressed into a hard cake. Pressing. The mill-cake is sprinkled with about 3 per cent. of water, and arranged in a series of layers -about 4 inches thick, separated by brass plates. A powerful pressure is brought to bear on the layers, which are subjected to the maximum pressure for about 10 to 15 minutes, when it is removed. Each layer is thus formed into a hard cake about an inch thick. G ranulating. The cake is broken into pieces by means of iron-toothed rollers revolving in opposite directions, their axes being parallel and the distance between them regulated as required. Fluted rollers are sometimes used. The pieces are passed through a succession of rollers, each series being closer together, by which the pieces MANUFACTURE. 25 are broken into others still smaller, which pass over a sieve to another roller, the small grains passing through the sieve into a receiver below, until the whole is reduced to the required size. The various-sized grains are separated by the sieves between the different rollers. Glazing. Several hundred pounds of the grained powder, containing from 3 to 4 per cent. of water, are placed in the glazing barrel, which is miade to revolve from 9 to 10 times per minute, and in some mills from 25 to 30 times per minute. Usually from 10 to 12 hours are required to give the required glazing. In this operation the sharp angles are broken off, thereby diminishing the dust produced in transportation, and the surface of the grain receives a bright polish. Dryin~g. The powder is spread out on sheets stretched upon frames in a room raised to a temperature of 1400 to 180~ by steam-pipes or by a furnace. The teimperature should be raised gradually, and should not exceed 180~, ventilation being kept up. Du.stinq. The powder is finally sifted through fine sieves, to remove all dust and fine grains. 15.' Roundr powder. In case of emergency, and when powder cannot be procured from the mills, it may be made, in a simple and expeditious manner, as follows: Fix a powder-barrel on a shaft passing through its two heads, the barrel having ledges on the inside; to prevent leakage, cover it with a close canvas glued on, and put the hoops over the canvas. Put into the barrel 10 lbs. of sulphur in lumps, and 10 lbs. of charcoal, with 60 lbs. of zinc balls or of small shot (down to No. 4, 0.014 in. in diameter nearly); turn it, by hand or otherwise, 30 revolutions in a minute. 26 GUNPOWDER.-MANUFACTURE. To 10 lbs. of this mixture thus pulverized, add 30 lbs. of nitre, and work it two hours with the balls; water the 40 lbs. of composition with 2 quarts of water, mixing it equally with the hands, and granulate with the graining-sieve. The grains thus made, not being pressed, are too soft. To make them hard, put them into a barrel having 5 or 6 ledges projecting about 0.4 in. inside; give it at first 8 revolutions in a mlinute, increasing gradually to 20. The compression will be proportionate to the charge in the barrel, which should not, however, be more than half full; continue this operation until the density is such that a cubic foot of the powder shall weigh 855 oz., the mean density of round powder; strike on the staves of the barrel froom time to time, to prevent the adhesion of the powder. Sift the grains and dry the powder as usual. That which is too fine or too coarse is returned to the pulverizing-barrel. This powder is round, and the grain is sufficiently hard on the surface, but the interior is soft, which makes.it unfit for keeping, and may cause it to burn slowly. This defect may be remedied by making the grains at first very small, and by rolling them on a sheet or in a barrel, watering them from time to time, and adding pulverized composition in small proportions; in this way, the grains will be formed by successive layers; they are then separated according to size, glazed and dried. It appears from experiments that the simple incoypoorcatiom, of the materials makes a powder which gives nearly as high ranges with cannon as grained powder. INSPECTION, PROOF, ETC. 27 The incorporated dust from the rolling-barrel may be used in case of necessity. INSPECTION, PROOF, ETC. 16. Proving powder. Before powder for the mil]i tary service is received from the manufacturer, it is inspected and proved. For this purpose, at least 50 barrels are thoroughly mixed together. One barrel of this is proved by firing three rounds fromn a musket, with service-charge, if it be musket powdel; if cannon or nammoth powder, from an 8-inch columbiad, with 10 lbs. and a solid shot of 65 lbs. weight and 7.88 inches in diameter; if it be mortar powder, fiom a 3-inch riflegun, with a charge of 1 lb. of powder and an expanding projectile weighing 10 lbs. The general character of the grain, and its fieedom fioom dust, are noted. Generalc qulities. Gunpowder should be of an evensized grain, angular and irregular in form, without sharp corners, and very hard. When new, it should leave no trace of dust when poured on the back of the hand, and when flashed in quantities of 10 grains on a copper plate, it should leave no bead or foulness. It should give the required initial velocity to the ball, and not more than the maximum pressure on the gun, and should absorb but little moisture from the air. Size of ycatin. There are five kinds of powder in the U. S. land service, depending on the size of the grain, viz.: Mcammnotlh for the 15-inch gun, Cannon for smaller sea-coast guns and mortars, lMortacr for field and siege cannon, Mlsitket for rifle-muskets, and Rifle for pistols. 28 GUNPOWDER.-INSPECTION, ETC. The size of the grain is tested by standard sieves made of sheet brass pierced with round holes. The diameters of the large and small holes are as follows, viz.: For Mammoth, 0.9 inch and 0.6 inch; for Cannon, 0.31 inch and 0.27 inch; for Mortar, 0.1 inch and 0.07 inch; for Musket, 0.06 inch and 0.035 inch. Not more than 5 per cent. should remain on the large, nor pass through the small standard sieves. Gravimetric density. Is the weight of a given measured quantity. It is usually expressed by the weight of a cubic foot in ounces. This cannot be relied upon for the true density when accuracy is desired, as the shape of the grain may make the denser powder seem the lighter. pecific gravity. The specific gravity of gunpowder must be not less than 1.75; and it is important that it should be determined with accuracy. Alcohol and water saturated with saltpetre have been used for this purpose; but they do not furnish accurate results. Mercury, only, is to be relied upon. /lfercury denesimeter. This apparatus was invented by Colonel Mallet, of the French army, and Al. Bianchi, and consists of an open vessel containing mercury, a frame supporting a glass globe communicating by a tube with the mercury in the open vessel, and joined at top to a graduated glass tube, which communicates by a flexible tube with an ordinary air-pump. Stop-cocks are inserted in the tubes above and below the glass globe, and a diaphragm of chamois-skin is placed over the orifice at the bottom of the globe, and one of wire-cloth over the upper orifice. INSPECTION, PROOF, ETC. 29 The operation consists as follows: Fill the globe with mercury to any mark of the graduated tube, by means of the air-pump; close the stop-cocks; detach the globe, full of mercury, and weigh it; empty and clean the globe; introduce into it a given weight of gunpowder; attach the globe to the tubes; exhaust the air till the mercury fills the globe and rises to the same height as before; shut the stop-cocks; take off the globe and weigh it as before. If we represent by a the weight of the powder in the globe, by P the weight of the globe full of mercury, by P' the weight of the globe containing the powder and mercury, and by D the specific gravity of the mercury. The specific gravities of the powder and the mercury being proportional to the weights of equal volumes of these two substances, we have a: P-P'+ca:: d: D Ca X I hence 1 P - P'+a A mean of three results will give the true specific gravity. If the powder is good in other respects, the density may vary fioml 1.67 to 1.79. Initial velocity. The initial velocity is determined by the Electro-Ballistic Pendulum. It should not be less than 1,050 feet for Mammoth, 1,225 feet for Cannon, 1,000 feet for Mortar and 975 feet, for Musket powder. Strairn on the gun. The strain on the gun is determined by Major Rodman's pressure-piston, an instrument which is attached to the breech of the proof gun, and the principles of which are explained on page 152., 30 GUNPOWDER.-INSPECTION, ETC. For Mammoth powder the pressure should not be more than 10,000 lbs., for Cannon, not more than 40,000 lbs., and for Mortar not more than 50,000 lbs. to the square inch. in8spection report. The report of inspection should show the place and date of fabrication and of proof, the kind of powder and its general qualities, as the number of grains in 100 grs., whether hard or soft, round or angular, of uniform or irregular size, and if free from dust or not; the initial velocities obtained in each fire; the amount of moisture absorbed; and, finally, the height of the barometer and hygrometer at the time of proof. 1_7. Packing. Government powder is packed in barrels of 100 lbs. each. The barrels are made of wellseasoned white oak; and hooped with hickory or cedar hoops, which should be deprived of their bark to render them less liable to be attacked by worms. Barrels made of corrugated tin are undergoing trial, to test their fitness to replace those made of wood. JdI s. on the barrels. Each barrel is marked on both heads (in white oil-colors, the head painted black) wzith the number of the barrel, the name of the manufacturer, year of fabrication, and the kind of powder,cannonz, (used for heavy cannon,) mortar, (used for mortars and field cannon,) or mnsjket -the mean initial velocity, and the pressure per square inch on the pressurepiston. Each time the powder is proved, the initial velocity is marked below the former-proofs, and the date of the trial opposite it. 18. Analysis. Whatever may be the mode of proof adopted, it is essential, in judging of the qualities of gunpowder, to know the mode of fabrication and the ANALYSIS. 31 proportions and degree of purity of the materials. The latter point may be ascertained by analysis. In the first place, determine the quantity of water that the powder contains, by subjecting it to a temperature of 212~, in a stove or in a tube with a current of warm air passing over it, until it no longer loses in weight. The difference in weight, before and after drying, gives the amount of moisture contained in the powder. To determine the quantity of 8altpet~re. In a vessel of tinned copper, like a common coffee-pot, dissolve 1,000 grains of powder, well dried before weighing, in 2,000 grains of distilled water, and heat it until it boils; let it stand a moment, and then decant it on a piece of filtering-paper, doubled exactly in the middle; this operation is repeated three times; at the third time, instead of decanting, pour the whole contents of the vessel on the filterl; drain the filterl, and wash it several times with 2,000 grains of water heated in the vessel, using in all these operations 10,000 grains of water. After passing through the filters, this water contains in solution all the saltpetre, the quantity of which is ascertained by evaporating to dryness. Dry the double filter with the mixture of coal and sulphur, and take the weight of this composition by using the exterior filter to ascertain the weight of that on which the composition remains; this weight serves to verify that of the saltpetre and to estimate the loss in the process. To -determnine the quantity of chac'coal directly. To separate the sulphur from the charcoal, subject the powder, either directly or after the saltpetre has been dissolved out, to the action of a boiling solution of the 32 GUNPOWDER. —INSPECTION, ETC. sulphide of potassium or sodium, which dissolves the sulphur and leaves the charcoal, the weight of which may be easily determined. It is important that the sulphides of potassium and sodium used in dissolving the sulphur, should contain no free potassa or soda; for each of these alkalies would dissolve a part of the carbon-particularly of the brown coal. The sulphide of carbon also dissolves the sulphur contained in powder, and may be used to determine the weight of charcoal which it contains. The charcoal, separated from the saltpetre and sulphur, is dried with care and weighed, and should then be submitted to analysis in an apparatus used for burning organic matters. The composition of the charcoal may be judged of by comparing it with the results obtained in the analysis of charcoal of known quality used in the manufacture of powder. To determine the quantity of Snlphlr' directly. Mix and beat in a mortar 10 giains of dry powder, 10 of carbonate of potassa, 10 of saltpetre, and 40 of chloride of sodium; put this mixture in a vessel (capsule) of platinum or glass, on live coals, and, when the combination of the materials is completed and the mass is white, dissolve it in distilled water, and saturate the solution with-nitric acid; decompose the sulphate which has been formed, by adding a solution of chloride of barium, in which the exact proportions of the water and the chloride are known. According to the atomic proportions, the quantity of sulphur will be to that of the chloride of barium used as 16. to 104. 19. Hygrometric qualities. The susceptibility of pow RESTORATION. 33 der to absorb moisture is due to the charcoal and the presence of deliquescent salts, principally chloride of sodium or common salt. The absorbent power may be judged of by exposing I lb. to the air in a moist place (such as a cellar which is not too damp) on a glazed earthen dish, for 15 or 20 days, stirring it sometimes so as to expose the surface better; the powder should be previously well dried, at the heat of about 1400. Wellglazed powder, made of pure material, treated in this way, will not increase in weight more than 5 parts in 1,000, or a half of one per cent. 20. Quickness of burning, The relative quickness of two different powders may be determined by burning a train laid in a circular or other groove which returns into itself, one half of the groove being filled with each kind of powder, and fire communicated at one of the points of meeting of the two trains; the relativequickness is readily deduced from observation of the point at which the flames meet. 21. Restoring unserviceable powder. When the quantity of water does not exceed 7 per cent., the powder may be restored by drying; this may be effected in the magazine, if it be dry, by means of ventilation, or by the use of the chloride of calcium for twenty or thirty days. Quick-lime may be used; but the use of it is attended with danger; on account of the heat evolved in slaking. When powder has absorbed from 7 to 12: per cent. of water, it may still be restored by drying in the sun or drying-house; but it remains porous and firiable, and unfit for transportation: in this case it is, better to work 3 34 GUNPOWDER.-PRESERVATION. it over. In service, it may be worked by means of the rolling-barrels, as described for making round powder. When powder has been damaged with salt water, or become mixed with dirt or gravel, or other foreign substances which cannot be separated by sifting, or when it has been under water, or otherwise too much injured to be reworked, it must be melted down to obtain the saltpetre by solution, filtration, and evaporation. _22. Storage, &c. In the powder-magazines, the barrels are generally placed on the sides, three tiers high, or four tiers if necessary; small skids should be placed on the floor, and between the several tiers of barrels, in order to steady them; and chocks should be placed at intervals on the lower skids, to prevent the rolling of the barrels. The powder should be separated according to its kind, the place and date of fabrication, and the proof range. Fixed ammunition, especially for cannon, should not be put in the same magazine with powder in barrels, if it can be avoided. Besides being recorded in the magazine book, each parcel of powder should be inscribed on a ticket attach-ed to the pile, showing the entries and the issue. 23. Preservation. For the preservation of the powder, and of the floors and lining of the magazine, it is of the greatest importance to preserve unobstructed the circulation of the air, under the flooring as well as above. The magazine should be opened and aired in clear, dry weather, when the air outside is colder than that inside the magazine; the ventilators must be kept free; no shrubbery or trees should be allowed to grow so near as to protect the building from the sun. The moisture of a magazine may be absorbed by chloride of calcium, EFFECTS OF GUNPOWDER. 35 suspended in an open box under the arch, and renewed from time to time; quick-lime, as before observed, is dangerous. The sentinel or guard at a magazine, when it is open, should have no fire-arms; and every one who enters the magazine should take off his shoes, or put socks over them; no sword or cane, or any thing which might occasion sparks, should be carried in. 24. Transportation. Barrels of powder should not be rolled for transportation; they should be carried in hand-barrows, or slings made of rope or leather. In moving powder in the magazine, a cloth or carpet should be spread; all implements used there should be of wood or copper; and the barrels should never be repaired in the magazine. When it is necessary to roll the powder, for its better preservation and to prevent its caking, this should be done with a small quantity at a time, on boards in the magazine yard. In wagons, barrels of powder must be packed in straw, secured in such a manner as not to rub against each other, and the load covered with thick canvas. EFFECTS OF GUNPOWDER.* 25. History, etc. The projectile arms of the ancients, such as bows, ballistas, and catapults, were operated by the same motive power-that of the spring. Although large masses were thrown from these machines, the velocity imparted was feeble, as the springs rapidly lost their power, from being bent; and * Vide PIOBERT'S Cours d'Artillerie. 36 GUNPOWDER.-ITS EFFECTS. the introduction of gunpowder, a more certain as well as powerful agent, gradually caused them to be superseded. As before stated, the power of this agent is essentially due to the almost instantaneous development of expansive gases and heat by combustion; and although its properties were known for a long time, its use was at first confined to fireworks and incendiary compositions alone. The advantage of using an agent capable of communicating great velocity to a projectile, arises not only from the intensity of the shock, the possibility of disabling a large number of men, and penetrating very resisting objects, but from the fact that it allows of the use of lighter machines, whereby the projectile can be directed with greater ease and certainty against its object. Although the combustible nature of powder was known in Asia from the earliest times, and its properties were described by Marcus Grsecus and Roger Bacon, its application to projectiles seems to have been a subsequent result of accident. It is stated that about the year 1330, Berthold Schwartz, a monk of Fribourg, was engaged in making experiments with a mixture of saltpetre, sulphur, and charcoal, such as described by Marcus Grfecus, and had left the mixture in a mortar, covered with a large stone, when it unexpectedly caught fire and exploded, throwing the stone to a distance with great force. The experiment was repeated, and with such success that military men saw at once that it could be applied to move large projectiles. Its progress as a projectile power, DIScovERY. 37 however, was comparatively slow, and it was only at the beginning of the 16th century that it was generally used for military purposes. For a long time after its introduction, gunpowder was used in the form of dust, or "mealed powder," from which it derived its name; but it was found difficult to load small arms with gunpowder in this condition, on account of the moisture which sometimes collects in the bore after a few discharges. To overcome this difficulty, it was given a granular form, and received the name of "musket powder." It was soon discovered, however, that two parts of grained powder produced as much effect as three parts of mealed powder; but the larger fire-arms of the day had not sufficient strength to resist this increased force, and mealed powder continued to be used until the close of the 16th century. At first, the ingredients of powder were converted into cake with a hand-pestle; a process which gave grains of very irregular size and shape. It was afterward discovered that the quality could be much improved by careful manipulation, without sensibly altering the proportions of the ingredients first established. Any improvement in gunpowder which increases its strength, also increases its injurious effects on the arms in which it is used. It becomes necessary, therefore, to study the form and thickness of fire-arms, and the nature of the agent whose operations they are intended to restrain and direct. It is impossible to embrace in a single glance the details of a phenomenon as complicated as the explosion of a charge of powder. The senses cannot detect the relations which exist between the partial operations of 38 GUNPOWDER.-ITS EFFECTS. a phenomenon, where they are produced with such ra. pidity that they seem blended into one. In this case the only sure method of investigation is to separately study the different facts, and then unite them as a whole, borrowing from the physical sciences a thorough knowlb edge of the substances operated upon. If the numerous circumstances which influence the results of the explosion of gunpowder, and the enormous expansive force which is developed in its limited duration, prevent us from accurately determining the measure of its effects, we can at least determine the limits between which this measure is included; which is sufficient for artillery purposes. From the results thus obtained were calculated the iron and bronze howitzers introduced to supersede those of Gribeauval's system. With less thickness of metal, these pieces were found to answer every requirement of service; a fact which tends to confirm the accuracy of the data from which they were constructed. 26. Explosion. The phenomenon of the explosion of powder may be divided into three distinct parts, viz.: ~ignition, inflammation, and combustion. By ignition is understood the setting on fire of a particular point of the charge; by inflammation, the spread of the ignition from one grain to another; and by combustion, the burning of each grain from its surface to centre. 27. Ignition. Gunpowder may be ignited by the electric spark, by contact with an ignited body, or by a sudden heat of 572~ Fahrenheit. A gradual heat decomposes powder without explosion by subliming the sulphur. Flame will not ignite gunpowder unless it COMBUSTION. 39 remains long enough in contact with the grains to heat them to redness. Thus, the blaze from burning paper may be touched to grains of powder without igniting them, owing to the slight density of the flame, and the cooling effect of the grains. It may be ignited by friction, or a shock between two solid bodies, even when these are not very hard. Experiments in France, in 1825, show that powder may be ignited by the shock of copper against copper, copper against iron, lead against lead, and even lead against wood; in handling gunpowder, therefore, violent shocks between all solid bodies should be avoided. The time necessary for the ignition of powder varies according to circumstances. For instance, damp powder requires a longer time for ignition than powder perfectly dry, owing to the loss of heat consequent on the evaporation of the water; a powder, the grain of which has an angular shape and rough surface, will be more easily ignited than one of rounded shape and smooth surface; a light powder, more easily than a dense one; and a powder made of a black charcoal, more easily than one made of red, inasmuch as the latter is compelled to give up its volatile ingredients before it is acted on by the nitre. 28. Combustion. The velocity of combustion is the space passed over by the surface of combustion in a second of time, measured in a direction perpendicular to this surface. The diameter of the largest-size grain of mortarpowder does not exceed 0.1 inch; the time of its combustion, therefore, is altogether too transient to be ascertained by direct observation. It may be deter 40 GUNPOWDER.-ITS EFFECTS. mined by compressing the composition into a tube and burning it, or by burning the "press-cake." In the latter case, take a prism of the cake about fourteen inches long and one inch square at the base. Smear the sides with hogs' lard, and place it on end in a shallow dish of Fig. 1'. water. The object of the lard is to preFig. 1. vent the spread of the flame to the sides; and the water is to prevent the lower end from being ignited by burning drops of powder. Set the upper end on fire, and note the time of burning of the column with a stop-watch beating tenths of seconds. In either way it will be shown that the composition,,if homogeneous, burns in parallel layers, and that the velocity of combustion is uninfluenced by the size of the column, or by the temperature and pressure of the surrounding gas. The velocity of combustion of dry French warpowder is thus found to be 0.48 in., and of English powder, which American powder closely resembles, it.is about 0.4 in. It may be shown by direct experiment that the burning of a grain of powder in a fire-arm, is progressive, and that the size of the grain exerts a great influence on the velocity of the projectile, especially in short arms. For this purpose take a mortar. eprouvette and load it with a single fragment of powder weighing forty-six grains; fire it, and the ball will not be thrown out of the bore; divide the same weight into seven or eight fragments, and it will barely be thrown out of the COMBUSTION. 41 bore; divide it into fifteen fragments, and it will be thrown about ten feet; fifty fragments will throw it about thirty feet; and the same weight of cannon-powder, about one hundred and seventy feet. The progressive burning of powder is further confirmed by the fact, that burning grains are sometimes projected from a gun with, sufficient force to perforate screens of paper, wood, and lead, at considerable dis, tances. It is even found that they are set on fire in the gun, and afterward extinguished in the air before they are completely consumed. The large grains of powder used in the fifteen-inch columbiad are thrown out burning, to a distance of one hundred yards. The velocity of combustion of powder varies with the nature, proportion,, trituration, density, and condition of the ingredients. Purity of ingredients. To secure the greatest velocity of combustion, it is necessary that the nitre and sulphur should be pure, or nearly so. This can always be effected by a proper attention to the prescribed modes of refining; but with the charcoal it is different, for the part which it plays in combustion depends upon certain characters which are indicated by its color and texture. The velocity of combustion will be greater for red charcoals than those that are black and strongly calcined; and for light and friable charcoals, than those that are hard and compact. It appears, in fact, to be nearly proportioned to the combustibility of the charcoals given in the tables on page 19. Proportions. The proportions of. the ingredients have a very great effect on the combustion; by varying them, all velocities between 0 and.55 inch can be 42 GUNPOWDER. —ITS EFFECTS. obtained; the latter number can scarcely be exceeded. The proportions which give a maximum, appear to be comprised between the two following: Nitre, 76. Charcoal, 15. Sulphur, 9. " 76. " 14. " 10. As it is often useful in preparing fireworks to know the proportions which will give a certain velocity of combustion, a table is given of a series of proportions of nitre, sulphur, and charcoal, and the corresponding velocities of combustion: Sixty parts of nitre, compounded with certain proportions of sulphur and charcoal, gave the following velocities: Parts of Black Charcoal. Parts of 0 5 10 11 15 20 30 60 Sulphur. Inch. Inch. Inch. Inch. Inch. Inch. Inch. Inch. 0.0.02.11.14.24.34.43.07 5.0.05.24.30.43.47.35.00 8.0.06.50.51.49.41.20.00 10.0.08.47.49.47.39.16.00 15.0.11.43.44.36.35.14.00 20.0.16.39.40.38.30.10.00 30.0.27.34.33.29.21.01.00 60 o000 00 00. 00. 00. oo Io It will be seen that the proportions 6-1-1 are among those that give the greatest amount of gas in a given time, other circumstances being equal; for the TRITURATION. 43 reason, that the weight burned during this time is greater, and because each unit of weight gives a greater volume of gas. Trituration. Trituration of the ingredients increases the velocity of combustion; and this increase is much greater as the proportions approach those which give the greatest velocity. For the results of experiments on this point, see accompanying table: Velocity of combustion. Composition. * i~ I<~~ | BRemarks. A. B. C. Hours. Inches. Inches. Inches. 0.12.13.0189 Compositions dry. 1.31.25.0192 Nitre. Ch'coal. Sulphur. Composition. 2.38.29.0200 A, 75.00 12.5 12.50 Gunpowder. B, 68.00 12.0 28.00 Fuze composition. 3.40.32.0204 C, 66.66 2.0 31.34 Port-fire " 4.44.34.0212 The nitre was taken as it came from 5.46.35.0216 the refinery. The sulphur and charcoal 10.48.37.0236 had already been triturated in the rolling-barrels. D)en8ity. For each set of proportions, the maximum velocity corresponds to a very small density. By increasing the density, the velocity is diminished; and more rapidly for qutick compositions than slow ones. When in the form of a dust, gunpowder composition burns more slowly without compression than with it. For the results of experiments on the preceding compositions, see the following table; the trituration was extended to ten hours: 44 GUNPOWDER.-ITS EFFECTS. Velocity of combustion. Density. Composition. Remarks. A. B. C. 0.80.360.310 The pulverized composition is simply poured into a tube, and settled by striking lightly on a table. 1.00.440.410.0319 The composition poured in as above, and compressed under a weight of 22 lbs. without shock. 1.20.470.390.0295 Composition driven with a mallet weighing 2.2 lbs., falling through a height of 3.9 inches. 1.40.480.380.0252 Same, save the height, which was 27 inches. 1.60.890.366.0224 These densities were obtained by increasing the number of blows with 1.80.443.360.0220 the mallet for each ladleful of composition. 2.00.340 The density of a composition under the 2.16.330 same pressure, increases with the trituration of the ingredients. Jifoisture. By moistening the composition with pure water, alcohol, or vinegar, and then drying it completely, the velocity of combustion is increased. With.pure water alone, this increase of velocity may amount to 0.1 of an inch. On the contrary, the velocity is diminished where oils, fatty or resinous substances, are added to the composition, or when it incloses water or other liquids. Dry Powder, or one containing g per cent. of moisture, has a velocity of 0.4S in. "( i; At L; " " 0.89 in. "4 " 2~ 2 " " 0.883 in. 29. Law of formation of gaseous products. When the form and size of the grains and the velocity of combustion are known, we can ascertain, at any given mo FORMATION OF GASEOUS PRODUCTS. 45 ment, the amount of powder consumed, as the velocity is uniform and independent of the surface. Spjherical yrain. Take a spherical grain of powder of homogeneous structure, one that will completely burn up in -'- of a second. Apply fire at any point of its surface, the flame will immediately envelop it, and burn away the first spherical layer; if, for example, we suppose the Fig. 2. time of this partial combustion be — L of the time required to burn up the entire grain, then the radius of the remaining sphere will be only -9, of the first; but the volumes of spheres being to each other as the cubes of their radii, the primitive sphere will be to the one which remains after the burning of the first layer, as 1.0 is to 0.729, the cube of.9. Subtracting the second of these numbers from the first, we shall have 0.271, which expresses the difference of volumes of the two spheres, or the amount consumed in the first -1- of time, compared to that of the entire grain. By making similar calculations on the other layers, we shall obtain the results contained in the following table: Time of'burning.................. 0.000.100.200.800.400.500.600.700.800.900 1.000 Decreasing radii................... 1.000.900.800.T00.600.500.400.300.200.100 0.000 Volumes of grain.................. 1.000.729.512.343.216.125.064.027.008.001 0.000 Volumes burnt.............. 0.000.271 A4SS.657.84.875.986.973.992.999 1.000 Volumes burnt in each 0".01....... 0 000.271.217.171.127.091.061.087.019.007 0.001 It will be seen from this, that for equal intervals of time, those taken in the first period of combustion give forth very much larger amounts of gas than those taken in the last. If, instead of a sphere, we suppose the 46 GUNPOWDER.-ITS EFFECTS. grain to be a polyhedron circumscribing a sphere, the burning layers being parallel, the decreasing grain will continue to. be a similar polyhedron, circumscribing a sphere. The results given in the table will be strictly true for this case, as well as for grains of conical or cylindrical form, provided their bases be equal to their heights. General formula. A general formula may be de. duced to show the amount of gas developed at any instant of the combustion of a grain or charge of powder. For this purpose take a spherical grain of powder, and consider-it inflamed over its entire surface. Let t represent the time of burning, from the instant of ignition to the moment under consideration: t the time necessary to burn from the surface to.the centre, or total combustion:?, the radius of the grain. Since the combustion passes over the radius R in the time t', the velocity of combustion is equal t, and B~ t for the time t, it will pass over the space t- or R the radius of the decreasing sphere will therefore be R(1? tI ) The volume of the grain of powder 4 and that of the decreasing sphere are 4-r-R3 and 3 4 8 3Tr 11(1-to respectively; and their difference, or the quantity of powder burned, will be equal to 3 - t GENERAL FORMULA. 47 The first factor of this expression represents the primitive volume of a grain of powder, and the other expresses the relation of the volume burned to the primitive volume. The same expression will answer for all the grains of a charge of powder, if they are of the same size and composition; consequently, if we let A represent the volume or weight of the grains composing a charge of powder, the quantity remaining unburned after the time t will be represented by A (- —; and the quantity burned by -A(14 (1 - ) ) Although the grains of powder are not spherical, their sharp angles are partially worn away by rubbing against each other in glazing and in transportation; and the mode of fabricationl and inspection reduces the variation in size within narrow limits; therefore, if we examine the influence which the actual form and size of the grains exercises over the phenomenon of combustion of powder, we shall find that the effect varies J~ut slightly from that due to the spherical form. A4p=plication to ordinary powder. Take a grain of oblong form, like that of a spheroid, or cylinder terminated by two hemispheres: it will present a greater surface than a spherical grain of the same weight, and consequently the amount of gas formed from it in the first instants of time, will be greater, and the duration of the combustion will be less. It can be shown, howvever, that so long as the size of the grains is kept within the regulation limits, this influence will be slight. To do this, take an oblong grain the cylindrical part of 48 GUNPOWDER.-ITS EFFECTS. which has a diameter of.054 in., let it be terminated by two hemispheres, and have a total length of.097 in. (these being the minimum and maximum size of a grain of French cannon-powder, respectively); its weight will be about.07 grain, or 2w of a gramme, and with a velocity of combustion of 0.48 it will take 0.056" to burn up completely. French war-powder is composed of grains of different weights, numbering about 310 to every gramme, or 15.4 grs. Troy. If, therefore, powder contain oblong grains of the size stated above, there must be others still smaller: if we suppose them to be-in equal quantities, and the larger to be,-v-o of the unit of weight, then the smaller must be equal to Tkv of the unit of weight; which would be equal to spheres with a radius of 0.028 inch. Comparing the quantities of gas developed in intervals of.008", or about —.of the time necessary for the combustion of the smallest grains, we obtain the result in the following table:Relation of the volulme of powder burned, to the volKinds of grains of Powder. nie of the grains after a time of Ol.00S_ 0//.016 0".024 0".032 0//.040 0".048 0".056 -Elongated grains, diamr..054 in.; length, 0.098 in.,-210 to the gramme, or 15.4 grs.,.. 310 0.555 0.737 0. 8640: 946 0.98 1.000 Spherical grains o, 410 to the gramme, or.056 in. diameter, 0.357 0.616 0.7940.907 0.968 0.994 0.999 Elongated and spherical grains as above, in equal quantities, forming a mixture of 310 to the gramme,.0.3330.585 0.766.8850.958 0.990 0.999 Spherical grains of 310 to the gramme, or 0.063 in. diameter, 0.330 0.580 0.758 0.875 0.948 0.985 0.998 Difference between mixed grains and spherical grains of the same mean weight. 0.003 0.005 0.008 00101010.010 0.005 0.001 The differences in the results do not much exceed,o0 0 INFLAMMIATION. 49 and may be neglected in practice; we may accordingly consider all the grains of a charge of powder as spheres with radii corresponding to their mean weight. Tlis8 mean weight is cn irnj2ortant elnment, and may be determined by counting the numnber of grains in a given charge, and dividing the weight of the charge by this number. In war-powder the largest portion of each grain is burned in the first two-tenths of the time required to consume the entire grain: as it has been shown that a grain of ordinary cannon-powder requires 0.1 second for its combustion, the largest portion of the grain will be burned in the first -2 — of a second. If we consider the velocity of the projectile on leaving a gun, and the time necessary to overcome its inertia in the first period of its movement, we shall see that a very large portion of each grain is burned up before the projectile leaves the gun. If the size of the grain be increat.ed, the effect will be to diminihs, the amount of yga evolved in the first instant8 of time, cand to cliniminis the pressure on the breech.'X This principle has been made use of lately to increase the endurance of large cannon. 29. In[flammation. When grains of powder are united to form a charge, and fire is communicated to one of them, the heated and expansive gases evolved, insinuate themselves into the interstices of the charge, envelop the grains and ignite them, one after the other. * This ideahas been carried out more fully in the experiments of Captain Rodman, by converting the powder into one or more cakes, which are perforated with numerous small holes for the passage of the flame. In this way a large portion of the powder is consumed on an increasing instead of a decreasing surface, and the amount of gas given out in the last moments will be greater than in the first; and thus the strain on the breech of a gun may be very much diminished without proportionately diminishing the velocity communicated to the projectile. For actual results obtained with this kind of powder, see Note appended to section 109. 4 50 GUNPOWDER. —ITS EFFECTS. This propagation of ignition is called inflammation, and its velocity the velocity of inflammation. It is much greater than that of combustion, and it should not be confounded with it. The velocity with which inflamed gases move in a resisting tube, like a cannon, is very great. Hutton calculated it to be from 3,000 to 5,000 feet per second; and Robins determined it by experiment to be about 7,000 feet per second. But when these gases are forced to pass through the interstices of powder, the resistance offered will considerably diminish the velocity of their expansion: it is found to vary with the form and size of the grains; and may be supposed to be reduced to 33 feet per second. The velocity of combustion, as before stated, is only.48 inch per second. Although the velocity of inflammation of a train of powder can afford but an imperfect idea of this velocity in a gun, it may be interesting to study it. The velocity of inflammation of a train of powder generally varies with the size of the grains, with the'quantity of powder employed, and the disposition of the surrounding bodies, as will be shown by the following results of actual etxperiment. The amount oA powder in each train was about.11 lb. to the linear foot, and the time corresponding to the distances was one second. On a" plane surface in the open air,. 7.87 feet. In an uncovered trough,... 8.13 " In a linen tube,... 11.38 " In the same tube placed in the trough, 7.48" In the trough covered up,. 27.88" INFLAMMATION. 51 These velocities are less than those obtained in firearms, for the reason that the powder is not only confined at the sides, but at one end, which was not the case in the experiment with the covered trough, where it could expand in both directions. A velocity of more than three hundred feet can be obtained by burning quick-match inclosed in a cloth tube. The size of the cross-section influences the velocity, as was shown by burning a train containing.062 lb. per foot in an open trough: the velocity was 5.77 feet, instead of 7.87 feet; and in a covered trough it was twenty feet, instead of 27.88. The velocity, therefore, increases with the cross-section of the train. To determine the influence of the size of the grains on the velocity of inflammation, two trains were fired, one composed of fine grains, and the other of large ones; the velocity of the first was 8.2 feet, and the second was 7.54. This difference was due to the greater amount of gas developed by the small grains in the first instants of combustion. The'nature of the charcoal exerts an influence, the black being more favorable to inflammation than the red. For a specific gravity of 1.3, the velocity is 7.5 feet. " "( "r 1.6, "," 7.2 " " " " 1.8, "' " 6.2 " Light powder is therefore found to be more inflammable than heavy. If the grains be round the interstices are larger, and more favorable to the passage of the flame, and the in X52 GGUNPOWDER.-PRODUCTS OF COMBUSTION. flamemation of the mass. If they be sharp and angular, they will close upon each other in such a way as to reduce the interstices; and although the ignition of such grains may be more rapid, its propagation will be diminished. It has been shown that, when powder is burned in an open train, fine powder inflames more rapidly than coarse; such, however, is not the case in fire-arms, owing to the diminution of the interstices. If a charge were composed of mealed powder, the flame could no longer find its way through interstices, and the velocity of inflammation and combustion would become the same. The velocity of inflammation of powder compressed by pounding is about.64 inch, while that of mealed'powder in the same condition is only.45 in. PRODUCTS, ETC., OF COMBUSTION. 30. Nature of products. Temperature and atmospheric pressure considerably influence the products obtained from burning gunpowder. When exposed in the open air to a temperature gradually increasing to 572~ Fahrenheit, the sulphur sublimrnes, taking with it a porNOTE.-By compressing grain-powder under a hydrostatic press it may be converted into a solid cake, and be used in loading fire-arms, in place of the ordinary cartridge. No cement is required to unite the grains, as the pressure brings the particles of the surface of the grains within the limits of cohesive attraction, in the same way that artificial limestone is formed by compressing sand. As the pressure diminishes the interstices of the grains, it also diminishes the velocity of inflammation, and the rapidity with which the charge is converted into flame. Experiments made at West Point, on some specimens of powder thus prepared by Dr. Doremus, of New York, showed that the pressure on the surface of the bore may be increased or diminished by diminishing or increasing the pressure on the cakes. The cakes were covered by a water-proof, but highly inflammable varnish, which protected the powder from moisture, without apparently diminishing its inflammability. NATURE OF PRODUCTS. 53 tion of the carbon. This was shown by Saluces, who passed the volatilized products through a screen of very fine cloth, and found carbon deposited on it. Powder may be, therefore, completely decomposed by a gradual heat, without explosion; but when suddenly brought in contact with an ignited body, the temperature of which is at least 572~ Fahrenheit, the sulphur has not time to sublime before explosion takes place The proportions for war-powder for the United States service are seventy-six parts of nitre, ten of sulphur, and fourteen of carbon. By the atomic theory the proportions should be 74.64 nitre, 11.85 sulphur, 13.51 carbon. If we adopt these last proportions, the formula for gunpowder becomes (NVO5+KO) + +3 C. If we suppose the ingredients to be pure, and to arrange themselves under the influence of heat according to their strongest affinities, there will result one equivalent of nitrogen, three of carbonic acid, and one of sulphide of potassium, for (N05 + KO) + S+ 3 C_ N+ 3 C02 + SI The products are, therefore, solid and gaseous. Usually, powder contains a slight quantity of moisture; the ingredients -are not absolutely pure, nor are they proportioned strictly according to their combining equivalents; it might be expected, therefore, that the actual would differ from the theoretical results. The actual gaseous products obtained by combustion are, principally nitrogen and carbonic acid, sometimes carbonic oxide, a little sunphuretted hydrogen, carburetted hydcrogen, and nitrous oxide. The solid products are, ulp/hicde of potas8siumn, sull-sate of'pota.ssa, carboonrare 54 GUNPOWDER. -PRODUCTS OF COMBUSTION. of potac8a (mingled with a little carbon), and traces of sulzphur.. When the sulphide of potassium comes in contact with the air, it is converted into sulphate of potassa, and gives rise to the white smoke which follows the explosion of gunpowder. A portion of the sulphide is sometimes condensed on the surface of the projectile, which accounts for the red appearance of shells, sometimres observed in mortar-firing. The solid products are probably volatilized at the moment of explosion by the high temperature which accompanies the combustion; but, coming in contact with bodies of much lower temperature, they are immediately condensed. In chambered arms, small drops of sulphur may be observed condensed on the sides of the bore, which show that the sulphur has been volatilized; and we know that good powder burns on paper and leaves no trace. This fact, however, was most com. pletely shown by the experiments of Count Rumford. This celebrated observer used a small eprouvette of great strength, which he partially filled with powder, and hermetically closed with a heavy weight. The powder was fired by heating a portion of the eprouvette to redness. Whenever the force was sufficient to- raise, the weight, the entire products escaped; when it was not, a solid substance was found condensed on the surface of the bore furthest from the source of heat. 31. Temperature. The temperature of the gaseous products of fired gunpowder has been variously estimated. Saluces determined by experiment that pure copper, which melts at a temperature of 4,622 Fahr., was not always melted by them; while brass, the melting DETERMINATION OF FORCE. 5A point of which is about 3,900 Fahr., was invariably melted; he was, therefore, induced to place their temperature at about 4,300 Fahr. As metals absorb a large amount of heat before melting, it is probable that the temperature of fired gunpowder is actually more than is here stated. DETERMINATION OF THE FORCE OF GUNPOWDER. 32. Absolute force. The absolute force of gunpowder is measured by the pressure which it exerts when it exactly fills the space in which it is fired. Various experiments have been made to determine mechanically the absolute expansive force of fired gunpowder, but with widely different results. Robins estimated it at 1,000 atmospheres, Hutton at 1,800, D'Antoni from 1,400 to 1,900, and Rumford carried it as high as 100,000 atmospheres.* These discrepancies arise, in a great measure, from the very great difference which exists between the expansive force of the gases in the different moments of combustion, and from a want of coincidence in the observations. The apparatus used by Rumford to determine this point consisted, essentially, of a small eprouvette, E, capaFig. 5. grains of powder. The orifice: * Rodman's experiments show the absolute pressure to be at least 13,333 atmospheres, or 200,000 lbs. to the square inch. 5 6 GUNPOWDER. —-FORCE. was closed: with a heavy weight, and the powder was fired by heating the stem of the eprouvette, S, with a redhot cannon-ball, B. For the first trial, he filled the eprouvette with 25 grains of the best quality of dry powder, and rested upon the cover the knob, C, of a 24-pd. gun, whose weight was 8,081 lbs. Notwithstanding its great strength, the eprouvette was burst at the first fire into two pieces; and the 24-pdr. was raised. Rumford endeavored to show from the weight thus raised, that the pressure of the gases on the sides of the eprouvette was greater than 10,000 atmospheres. He further attempted to show, that as the tenacity of good iron is equal to 4,231 times the pressure of the atmosphere on the same surface, and as the surface of rupture was 13 times that of the bore, the force necessary to produce the rupture of the eprouvette must have been 13 X 4,231, or 55,003 atmospheres. There are circumstances attending this experiment which should be taken into account, and which will very materially diminish this result. They are, the diminution of the tenacity of the iron, due to heating the eprouvette to produce explosion, and the incorrect method by which Rumford estimated the strength of a hollow cylinder subjected to a strain of expansion. 33. Relation between density and force. Experiments were continued, with a similar apparatus, to determine the relation between the density and the expansive force of fired gunpowder. The capacity of the eprouvette was nearly 25 grains. It was fired with vari-ous charges from 1 up to 18 grains; and the expansive force of each discharge was determined by the smallest weight necessary to close the orifice against the escape .DENSITY AND FORCE. 57 of the gas. With the results of 85 trials a table was formed, from which a curve was constructed which expresses the relation between the density and expansive force of fired gunpowder, from 1 to 15 grains. By analogy and calculation, this curve was continued up to a charge of 24 grains; and for the density corresponding to this charge, the pressure was found to be 29,178 atmospheres. This pressure is much greater than that developed in the explosion of projectiles and mines, owing to the low temperature of the surrounding surfaces, and the large amount of heat which they absorb. It is the same with cannon, for the most rapid firing does not raise the temperature of the bore above 210 Fahr., which is much below that of the eprouvette. Besides, the powder does not completely fill the space in rear of the ball; and, as powder burns progressively, this space is enlarged before the gases are completely developed, and consequently their density is diminished. There is also a loss of force by the escape of the gases, through the windage and vent. The following equation expresses the relation found to exist between the density and expansive force of charges of gunpowder, from 1 to 15 grains, fired in an eprouvette the capacity of which was 25 grains, or in other words, for charges in which the densities vary from.04 to.6::p= 1.841(905d)1lo362d; in which p represents the pressure in atmospheres, and d the density of the inflamed products. It will be seen from this equation, that the pressure s 8 GUNPOWDER. —FORCE. increases more rapidly than the density, since the exponent of the density is greater than unity. The density of the qayeS is equal to the weight oqf the powder bu-rned divided by the vpace occupied by the gases. By substituting this in the equation, we can determine the pressure exerted at any given instant of the combustion. Although this relation is deduced for a particular kind of powder, it may be used for all service-powders and service-charges without serious error, since the actual amount of gaseous products is nearly the same for all, and the densities of the highest service-charges never exceed -0.6. 34. Force of powder when inflalmmation is instantaneous. If the size, form, and density of the grains of a charge of powder, the velocity of combustion, and the * The accuracy of Rumford's formula has been lately verified by a series of experiments made by Captain Rodman. The apparatus used by this officer consisted of a very thick cast-iron shell, to which was attached an indenting piston for determining the pressure on the inner surface, or powder cavity of the shell. The following table shows the pressures calculated by the formula and the pressures obtained by the experiments, for three different densities: beasity. Pressure by Pressure by enity. mford's Formula. Rodman's Experiments. 0d —- o 1,290 lbs. 1,066 lbs. I 0l lo~- 2,900 " 2,525 l d=-. 3,700': 3,220" The lesser pressure obtained by Rodman's experiments may be in a great measure explained by the facts, that the shell was not heated, but fired with a friction tube, and that the gas was allowed to escape through the vent. Further experiments were made which show that so long as the volume of the charge bears the same proportion to the space in which it is fired, the pressure on the unit of surface remains the same, no matter what may be the amount of the charge. This follows also from Rumford's formula, since the value of p is not affected so long as d remains the same. FORCE. 59 space in which it is contained, are known, we can determine the density of the gaseous products at any particular moment of combustion. For this purpose, take the case in which the inflammation of the whole charge is considered instantaneous, and let P be the weight of the charge, d' the density of the composition of which the powder is made, Vthe space in which the gases expand, t' the time of combustion of a single grain, t the time since the combustion began, d the density of the gases at a given instant. According to section 29, the weight of powder remaining after a time, t, will be equal to P(i —-, P / t\\ and the volume will be equal to 1I(1 —J; the weight of gaseous products evolved will be equal to P(I- - i-; -and their density will be equal to this quantity divided by the space;, diminished by the space occupied by the powder unburnt at the end of the time t. Or,' ( ( _)8) Let represent the ratio of the weight of powder Let IT represent the ratio of the weight of powder which would fill the space V; to the weight of the charge P, and D the gravimetric density, or weight 60 GUNPOWDER. -FORCE. of a unit of volume of powder, we shall have the equation, D V D-VK or iK. ~ P D' and the formula for the density of the gaseous products becomes, d= I-(, DD (I ) (1) If the charge fill the entire space V, K= 1 and d-D1-( -t 1 -(I -- d When the grains are consumed, tt' and d —; and if K- 1, d-D. Having determined the mean density of the gaseous products at any instant of the combustion, we can determine the pressure exerted on the enclosing surfaces by means of Rumford's formula P= 1.841(905d)l XO'32d This value of P supposes that the entire charge is inflamed at the same time-a supposition that is not strictly correct, except for small and lightly-rammed charges. When the charge is large, and well-rammed, as in cannon, it is necessary to take into consideration the time of inflammation. 35. Density when the inflammationt is not instantaneous. In a majority of cases the preceding formulas will give the relation between the density and expan FORCE. 61 sive force of gunpowder, without sensible error; but when the grains are small, and the charge is compressed by ramming, the interstices are diminished in size, and the inflammation is comparatively less rapid; besides, the size and form of the charge exert an influence which increases with its length. It is proposed, therefore, to modify the formulas, and adapt them to the most general case, by considering the inflammation progressive. Take a charge of powder, of any form whatever, and consider it ignited at the point A, the inflammation will reach the surface of the concentric zone B, the radius of which is tv, in the time t, v being the velocity of inflammation. There will be portions of the charge situated within this zone which the flame will not have reached; others in which the combustion Fig. 6. is completed; and others, between these two, in which the inflammation is completed, but the combustion is only partially completed. See figure 7. Fig. 7. The extent of the inflamed zones being determined by the form and dimensions of the charge, exerts a great influence on the development of the gases, and consequently on their density. If the velocities of inflammation and combustion be known, the quantity of gas formed from each zone can be calculated, and the question becomes one of analysis. 62 GUNPOWDER.-FORCE. In this calculation, the integral limits which refer to the extent of the zones are determined by the surface of the charge; and those which refer to the progress of the combustion of the grains will be the point of ignition: and the. surface of inflammation; or, if o be the time necessary for the flame to reach the surface of the zone, the radius of which is x, the time of partial combustion of a grain of this zone will be t-o, and its complete combustion is expressed by the relation t=-t'+o0. For this zone the density of the gaseous products at the instant of inflammation will be d- 0, and when completely consumed d-ZD. The intermediate values may be determined by formula (1) by substituting t-0 for t, and supposing K 1, should the charge completely fill the space in which it is burned. Integrating between th6 determined limits, we obtain the mean density of the gases developed. The solution of this question, in a general sense, is very difficult, and requires the aid of the differential calculus. There are particular cases, however, where the solution is not difficult; for instance, where the charge is of cylindrical form and is placed at the bottom of the bore of a gun. 36. Calculation of the density of a charge of cylindrical form. Although the charge of a gun is ignited at the rear and upper portion, we may consider that all portions of the circular layer at the bottom are inflamed FORCE. 63 at once, and that the inflammation spreads by parallel layers throughout its extent. The space at the bottom of the bore, and the escape of gas through the vent, favor this supposition. Let 2L represent the total length of the charge, and o' the time necessary for the inflammation to pass over this length. Let us assume that ol=nt', t' being the time necessary for the combustion of a single grain of the charge; n, therefore, is the ratio of these times. The velocity of inflammation will be -, or -n; and -_ will represent the portion of the charge inflamed in the time t. The length of the charge which will be consumed (and no portion can be entirely consumed unless t>t') will be (t-t'); and the thickness of the burning layer will be the difference between these two quantities, or -; which is constant. If the area of a section of the charge, perpendicular to its axis, be taken as the unit of surface, the volumes may be represented by their lengths. Divide the length of the burning portion into a number, hb, of smaller sections, the length of one of the smaller sections will be equal to; if h be very large, the grains of each very small section may be considered in the same stage of combustion, and the radii of the consumed layers in each grain of the small sections will be represented in parts of the primitive radius, as follows: 64 GUNPOWDER.-FORCE. For the 1st, 2d, 3d... h —2, h —, A, sections. h h-1 h —2 3 2 1 A' 7 A' 7' 7' h' A7 The radii of the burning grains will be, 1 2 h-3 h-2 h 1' hA' **h' h' 1< and the corresponding volumes of the unburnt portions will be represented by. (1)3 2 3 lob ( 3 lb3 1 The volumes burned will be represented by, i 1- 1, 1_.... 1-( If D) represent the gravimetric density of the powder, the weight of each small section will be D, and nnh the weight of the gaseous products in all the sections will be -LD -h 13+28+33+43...+(h- 1)8 but we know in general terms that 13+28+3....z~, or z-z=(z 1 ))2; therefore the sum of the weights of the gases formed will be,,I) h (h(-1)) )2' If we suppose h, the number of sections, to be infinite, the above expression will reduce to LD LD qua, = 4 3 qa FORCE. 65 The portion of the charge entirely consumed being t-t' t-t equal to Itv-L, its weight will be t — LD, and the total weight of gaseous matter developed will be, t-t' +LI3 LD') The space which they occupy is equal to the volume of the inflamed portion of the charge, diminished by the volume of the unburned grains at the end of the time t; the volume of the burning powder is L, and its weight is /-_D. The weight of the portion burned being equal to 3 —-- that which remains unburned will be equal to 4 LR, and the density of the grains being d', their volume will be equal to I I-d. The volume into which the gases expand will consequently be equal to tL LD nt' 4 nd'Finally, the mean density of the gases at the instant i, will be, - =d= LD t D't/ 4 nd' 4d' From this it will be seen that the density is independent of the velocity of inflammation and length of the charge. The formula, however, can only be applied 66 GUNPOWDER.-FORCE. from the instant t- t' to that in which t= of -t', that is to say, so long as there exists a portion of the charge in which the combustion is ceasing on its posterior surface, and commencing on its anterior surface. Without committing a serious error, we can, however, apply the formula when t= t', because, in taking the sum of the cubes O+1l+2S+3a+...+ (h-1)3 from 1 to (h- 1)' it will only be necessary to take it from 2() to (h- 1)3, which makes an error equal to 13_ +23+33..-.(h 1), or -I of the total sum, as may be seen by replacing h by in the expression { h(-1)} 2 2 If the section of the charge, instead of being equal to the section of the bore of the gun,; is only, the gases being developed freely in a space K times greater, the density/!D will be diminished in an inverse ratio, and we shall have tD Kd4_ 37. Application to practice. Thus it will be seen that the density, and consequently the expansive force of fired gunpowder can be determined at each instant of combustion, either in the case in which the inflammation is considered instantaneous, or when considered progressive. The accuracy of the formulas was verified in France some years since, in the course of a series of experiments PRACTICAL RESULTS. 67 to determine the influence which the size and density of grains of powder exert upon the initial velocity of a projectile. There were six different sizes of grains tried, viz.:-.26 in.,.21 in.,.18 in.,.15 in.,.10 in. (cannon),.05 in. (musket); of each size there were six different densities, viz.:-1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and four different modes of manufacture, making 144 varieties of powder in all. The instruments used were the ballistic pendulum, the 4-pdr. gun pendulum, the mortar eprouvette, and the infantry musket. The results of calculation and direct experiment show a remarkable agreement, and may be summed up as follows, viz.:1. With the 4-pdr. gun the high densities gave greater velocities when combined with the smallest grains, and vice ve'sca, the low densities gave greater velocities when combined with the largest grains. The grains which gave the highest velocities possessed medium size and density, or a density of 1.5 combined with a diameter of 0.18 in. 2. With the mortar eprouvette, which fired a smaller charge than the 4-pdr. gun, the fine-grained powder gave almost'invariably greater velocities than the coarse. For a grain of.1 in. (or mortar size), the lowest densities gave the best results, and for a grain of.05 in. (or musket size), the highest densities gave the best results. 3. With the infantry musket, and a still smaller charge, the superiority of fine grains was more marked for all densities, and particularly so for the least. It would appear firom the foregoing, that the size and 68 GUNPOWDER.-GUN-COTTON. denslty of grains of powder should be increased in a certain ratio with the weight of the projectile to be moved, the size of the charge, and the length and diameter of the bore in which the powder is burned; and it is for this reason that five different powders have been adopt ed for the military service of this country (see page 27). GUN-COTTON. 38. Gun-cotton, or pyroxile. The action of nitric acid on such vegetable substances as saw-dust, linen, paper, and cotton, is to render them very combustible. In their natural state these substances are almost entirely composed of lignine, the constituents of which are oxygen, zydrogen, and carbon; nitric acid furnishes nitrogen, a substance which enters into the composition of nearly all explosive bodies. Gun-cotton was discovered by Prof. Sch6nbein, and published to the world in 1846. His method of preparing it consists in mixing three parts of sulphuric acid, sp. grav. 1.85, with one part of nitric acid, sp. gr. 1:45 to 1.50; and when the mixture cools down to between 50~ and 600 Fahr., clean rough cotton, in an open state, is immersed in it; when soaked, the excess of acid is poured off, and the cotton pressed tightly to remove as much as possible of what remains. The cotton is then covered over and left for half an hour, when, it is again pressed, and thoroughly washed in running water to remove all free acid. After being partially dried by pressure, it is washed in an alkaline solution made by dissolving one ounce of the carbonate of potash in a gallon of water. The free acid being thus expelled, it GUN-COTTON. 69 is placed in a press, the excess of alkaline solution expelled, and the cotton left nearly dry. It is then washed in a solution of pure nitrate of potash, one ounce to the gallon, and being again pressed, is dried at a temperature of from 150~ to 170. The sulphuric acid has no direct action on lignine, its use in the preparation of pyroxile being to retain the water abstracted from the cotton, and prevent the solution of the compound, which would take place, to a greater or less extent, in nitric acid alone. Cotton, in its conversion into an explosive substance, increases very considerably in weight, owing to the formation of a new and distinct chemical compound. Gun-cotton, when properly prepared, explodes at a temperature of about 380~ Fahr. It will not, therefore, ignite gunpowder, when loosely poured over it. Under ordinary circumstances, the electric spark will not explode it; but if the fluid be retarded in its progress by being passed over the surface of a string moistened with common water, and in contact with the cot. ton, explosion will follow. From the experiments of Major Mordecai, made at Washington arsenal, in 1846, the following facts regarding the use of this substance in the military service, were ascertained:1. The _projectile force, when used with moderate charges in musket or cannon, is equal to that of about twice its weight of the best gunpowder. 2. When compressed by hard ramming (as in filling a fuze), it burns slowly. 3. By the absorption of moisture, its force is rapidly diminished, but it is restored by drying. T 0 GUNPOWDER.-GUN-COTTON. 4. Its ex2i$loive force, or bursting effect, is in a high degree greater than that of gunpowder. In this respect the nature of gun-cotton assimilates much more to that of the fulminates than to gunpowder. It is, consequently, well adapted for many purposes in mining. 5. Gun-cotton, well prepared, leaves no perceptible stain when a small quantity is burnt on white paper. 6. It evolves little or no smoke, as the principal residue of its combustion is water and nitrous acid; the latter is made sensible by its odor, and by its effects on the barrel of a gun, which will,soon be corroded by it, if not wiped after firing. T. In consequence of the quickness and intensity of action of gun-cotton, when ignited, it cannot be used with safety in our present fire-arms. An accident of service, such as that of inserting two charges into a musket before firing (which frequently occurs), would cause the bursting of the barrel; and it is probable that the same result would be produced by regular service charges, repeated a moderate number of times. NOTE.-The following is said to be the improved method of preparing guncotton for the Austrian service: The cotton is immersed in the strongest preparation of acid-one part of nitric to three parts of sulphuric-and is permitted to remain in the acid bath for forty-eight hours. It is then washed in a stream of running water for four, six, or eight weeks, so as to remove every trace of free acid, which is not the case with gun-cotton made elsewhere. It is prepared for service by spinning it into a thread, which is wound around a stick to form it into a cartridge of the required size. Thus prepared, the inflammation, which depends on the compactness of the mass of fibres, is reduced to a safe limit for cannon, and at the same time the means afforded of rendering the explosive effect of the different cartridges uniform. It is stated that the Austrian Government is so far pleased with this substitrte for gunpowder, as to have forty batteries of rifled field artillery prepared expressly for its use. PROJECTILES. 71 CHAPTER II. PROJECTILES, 39. Definition. A projectile is intended to reach and strike, pass through, or destroy, a distant object; the effect of a projectile varies with its form and the material of which it is composed. To destroy an object against which it is thrown, a projectile should have certain hardness and tenacity; if it be softer and less tenacious than the object, it will spread out laterally, or break into pieces, and presenting a greater surface, will meet with greater resistance, and consequently penetrate less than if it had preserved its primitive form. Great density is also favorable to penetration, inasmuch as it gives a projectile a greater mass for an equal surface. 40. Materials. Stone, lead, wrougyht and cast iaron are materials, each possessing peculiar advantages for projectiles, according to the circumstances under which they are fired, and the objects against which they are used. Stone. Stone projectiles were used before the invention of gunpowder, and very generally after it, until the year 14'00, vwhen the French made them of cast iron. The defects of stone as a material for projectiles, are a want of density and tenacity, which requires it to be used in large masses, and fired with comparatively small charges of powder. The effect of stone balls against 72 PROJECTILES. the walls of ancient cities was very great, but against modern fortifications, where the walls are sustained by large masses of earth, their effect is very slight. Until quite lately, bronze guns, throwing stone balls of enormous calibre, were used by the Turks in defending the passage of the Dardanelles. It is stated that when the English fleet, under Admiral Duckworth, forced the passage of these straits, a stone ball weighing 800 lbs. struck and nearly destroyed the English admiral's ship, and that one hundred men were killed and wounded by it. Lead. Lead as a material for projectiles, possesses the essential quality of density; but it is too soft to be used against very resisting objects, since it is flattened even against water. From its softness and fusibility, large projectiles of this material are liable to be disfigured, and partially melted, by the violent shock and great heat of large charges of powder. Its use is chiefly confined to smallarms and case-shot, which are generally-directed against animate objects. These defects of lead may be correct-.ed, in a measure, by alloying it with tin, antimony, &c. Wrought iron. When great strength and density, combined, are required in a projectile, wrought iron may be used, but it is generally attended with considerable expense. Ccbs.t iron. The introduction of cast iron, for large projectiles, was an important step in the improvement of artillery, as it unites in a greater degree than any other material, the essential qualities of hardness, strength, density, and cheapness; it is exclusively used for this purpose in the United States' service. CLASSIFICATION. 73 Compound. Compound projectiles are sometimes made so as to combine the good and correct the bad qualities of different metals. Thus, at the siege of Cadiz, cast-iron shells filled with lead, forming projectiles of great strength and density, were thrown from mortars to a distance of three miles and three quarters. For rifle-cannon, projectiles are made occasionally of cast iron, and covered with a soft coating of lead, or other soft metal, to obviate the serious results that might arise from the wedging of the flanges in the grooves of the gun. Such is the construction of Armstrong's projectile in England, and Sawyer's and others, in this country. In the rifle-cannon lately used by the French army in Italy, it is stated that the flanges which projected into the grooves of the bore were made of tin. Considerable success has also been attained in uniting cast iron and wrought iron, and cast iron and soft metal, in such manner as to attain the strength of one metal, and the softness and expansibility of the other. 41. Classification. Projectiles may be classified according to their form, as 8spherical and oblong. Spherzical projectiles. Spherical projectiles are commonly used in smooth-bored guns, and for this purpose possess certain advantages over those of an oblong form: 1. They present a uniform surface to the resistance of the air as they turn over in their flight. 2. For a given weight they offer the least extent of surface to the resistance of the air. 3. The centres of figure and inertia coincide. 4. They touch the surface of the bore at only one point; they are therefore less liable to wedge in the bore, and endanger the safety of the piece. 74 PROJ]ACTILES. 5. Their rebounds on land and water being certain and regular, they are well suited to rolling and ricochet firing. Oblong projectiles. The great improvements which have been made within the last few years in the accuracy and range of cannon and small-arms, consist simrzy in the use of the oblong instead of the spherical form of projectile. The superiority of the oblong form has been long known, and for many years used in the sporting rifles of this country; but serious obstacles have always stood in the way of its general adoption into the military service. To attain accuracy of flight and increase of range with an oblong projectile, it is necessary that it should move through the air in the direction of its length. Though experience would seem to show that the only sure method of effecting this, is to give it a rapid rotary motion around its long axis by the grooves of the rifle, numerous trials have been, and are now being made, to produce the same effect with smooth-bored arms. Centre of gravity, &c. One of the simplest plans used for this purpose, is to place the centre of gravity, or inertia, in advance of the centre of figure, or resistance. If these points be situated in the long axis of the projectile, as they should be, the forces of propulsion and resistance, which act in opposite directions, will cause it to coincide with the line of flight. This plan was tried on a hollow projectile in the time of Louis XIV., by dividing the cavity into two compartments by a partition, and filling the front one with bullets, and the rear one with powder; but the flight SOLID PROJECTILES. 75 of these projectiles was uncertain and irregular, and it was observed that some of them burst in the air, and that others struck the object sidewise. Another plan of this kind, proposed by Thiroux, is to make the projectile very long, with its rear portion of wood, and its point of lead or iron, somewhat after the manner of an arrow; but it does not appear that that method has ever been submitted to the test of practice. OClain-ball. To arrest the motion of rotation of an oblong projectile, thrown under high angles, and with a moderate velocity, it has been proposed to attach a light body to its posterior portion, by means of a cord or chain, which will offer a resistance to the flight of the projectile, and cause it to move with its point foremost. NcGail-all. This is a round projectile, and has an iron pin projecting from it to prevent it from turning in the bore of the piece. Grroovecl balls. Attempts have also been made to give an oblong projectile a motion of rotation around its long axis, by cutting spiral grooves on its base for the action of the charge, or by cutting them on the forward part for the action of the air. These plans have not succeeded in practice, for the reason, perhaps, that the projectile naturally turns over end for end, and the air and charge do not act on the grooves with sufficient promptness, energy, and certainty to prevent it. 42. solid shot. Projectiles may be further classified according to their structure and mode of operation, as solid, hollow and case.hot. Solid projectiles. Solid projectiles are used in gquns and smnall-ars, and produce their effect by impact 7T6 - - PROJECTILES. alone. When used in heavy guns they are known as solid shot, round shot, or shot. They are made of cast iron, and on account of their great strength and density, and the comparatively large charges of powder with which they are fired, are used when great range, accuracy, and penetration are required. They are the only projectiles that can be used with effect against very strong stone walls, or floating batteries covered with wrought-iron plates. Solid shot for guns are classified according to their weight, which, in the United States' land service, is as follows, viz.: Field service, 6 and 12 pounders. Siege service, 12, 18, and 24 pounders. Sea-coast service, 32 and 42 pounders. Solid shot for columbiads are classified according to the diameter of the bore, as 8 and 10 inch solid shot. 43. Bullets. The object of small-arms is to attain animate objects; their projectiles are, therefore, made of lead, and are generally known as bullets. They are both round and oblong; but in consequence of the great improvements that have been made of late, in adapting the principle of the rifle to small-arms, the oblong ball is now very generally used in all military services, the round bullet being chiefly retained for use in case-shot. IRound bullets. Round bullets are denominated by the number contained in a pound; this method is often used to express the calibre of small-arms; as, for instance, the calibre of the old musket was 1 to the pound, and the rifle was 32. In 1856, these two calibres were replaced by one of 24 to the pound, that of the new rifle musket. The number is sometimes prefixed to the word gauge, in which case the rifle-musket would SHELLS. be called a 24-gauge gun. This mode, however, is principally used to designate sporting arms. The oblong bullet is denominated by its diameter and weight; for instance, the new rifle-musket ball has a diameter of 0.58 in., and weighs 540 grains. Oblong bullet. The oblong bullet at present used in the United States' service, is composed of a cylinder surmounted by a conoid -the conoid being formed of the arcs of three circles. The cylinder has three grooves cut in it, in a direction perpendicular to its axis, to hold the Fio.. 9. grease necessary for lubricating the bore of the piece in loading, and possibly to guide the bullet in its flight, after the manner of the feathers of an arrow. A conical cavity is formed in the bottom, in which the gas of the charge expands, and forces the sides of the bullet into the grooves or rifles of the gun. From these grooves it receives a rotary motion around its long axis, which prevents it from turning over in its flight.44. shelns. Under the head of hollow e/ot are included shells for guns, howitzers, and mortars, and hand and rampart grenades. These projectiles are all made of cast iron; and for guns and field howitzers their calibres are expressed by the weight of the equivalent solid shot, as 12, 24, and 32 pound shells; and for all other howitzers and mortars, by the diameter of the bore of the piece, as 8 and 10 inch shells. Shells have less strength to resist a shock, they are therefore fired with a smaller charge of powder, than 78 PROJECTILES.-SHELLS. solid shot. Their weight, and consequent mean density, is generally about two-th at of a solid shot of the same size. Shells act both by impact and explosion, and are used against animals and such inanimate objects as will not cause them to break on striking. The principal parts of a spherical shell are: 1. The ccv7oty —-the shape of which is similar to and concentric with the exterior. The use of the cavity is to contain a bursting charge of powder, if the object be merely to destroy by explosion; or a bursting charge and incendiary composition, if the object be to destroy by explosion and combustion together. The size of the cavity should be as large as possible, to produce the greatest explosive -effect; but as the shell should have sufficient strength to resist the shock of the discharge, and sufficient weight to overcome the resistance of the air, the size of the cavity will necessarily be subordinate to these conditions, which fix the thickness of the metal. 2. The fuze-hole, which is used in inserting the bursting charge, and to hold the fuze which communicates fire to it. As the presence of the fuze-hole diminishes the effect of the bursting charge, the diameter of its orifice should be as small as possible. 3. The eares are two small recesses made near the fuze-holes of all shells larger than a 42-pounder, for the purpose of inserting the "hooks," and lifting the shells up to the bore of the piece in loading. A small hole is sometimes made in the upper hemisphere of shells, for the purpose of charging them after the fuze is driven; but late improvements in the construction of the fuze allow it to be dispensed with, so that the powder can now be poured GRENADES. 79 directly through the fuze-plug, and the charging can be deferred until the moment of loading. Fig. 10 represents a mortar-shell, and fig. 11 a shell used in a gun or sea-coast howitzer. The mortar-shell is fired with a lighter charge of powder than the gunshell, and has therefore less thickness of metal. The fuze-hole of the gun-shell, is reinforced with metal, so that the fuze will not be driven in by the force of the discharge. This reinforce serves, in a measure, to compensate for the metal taken out of the fuze-hole, and renders the shell more concentric. a.. Fuze-hole. b.. Reinforce. c..Cavity. d.. Sides, or thickness of metal. e.Ears. Fig, 10. Fig. 11. 45. Grenades. The hand grenade, as its name indicates, is. a projectile thrown from the hand, against troops in mass. The particular projectile'used for this purpose, in our service, is the 6-pounder spherical case-shot. Rampart Grenacde. Rainpart grenades are intended to be rolled down the rampart of a work, to protect a breach against the attack of a storming column. Shells of any size will answer for this purpose, and particularly those which are unserviceable for ordinary purposes. Grenades are filled with a bursting charge, and are 80 PROJECTILES.-CASE-SHOT. armed with a short fuze,* which is lighted by a match in the hands of the grenadier immediately before it is thrown. They act by the force of their explosion alone. 46. Case-shot. Case-shot are a collection of small projectiles enclosed in a case or envelope. The envelope is intended to be broken in the piece by the shock of the discharge, or at any point of its flight, by a charge of powder, enclosed within it; in either case, the contained projectiles continue to move on after the rupture, but scatter out into the form of a sheaf or cone, so as to cover a large surface and attain a great number of objects. These projectiles can only be used with effect against animate objects situated at a short distance from the point of rupture. The three principal kinds of case-shot in use are garae, cannister, and spherical ca8e-shot, or shrapnel. They are adapted to all guns and howitzers below those of 10-inch calibre, and receive their name from the pieces in which they are used.:_'/____ Gra~cpe-shot. A grape-shot is composed of nine small cast-iron balls, disposed in three layers of three' balls each. Formerly the balls were held together by a covering of canvas and network of twine; but the present Fig. 12. method is more simple and durable. * Ketchum's hand grenade, which has lately been introduced into the American service, is a small, oblong percussion shell, which explodes on striking a slightly resisting object. To prevent accidents, the "plunger," or piece of metal which communicates the shock to the percussion cap is not inserted in its place until the moment before the grenade is thrown. CASE-SHOT. 81 The parts of a stand of grape are, two plates, a, a, see Fig. 12, for the top and bottom layers; two rings, Z, 6, for the intermediate layer, and a screw-bolt, c, which passes through the plates and unites the whole. A handle is formed by passing a piece of rope-yarn through two holes in the upper plate, and tying the ends into knots to prevent them from pulling out. Grape-shot are used in all except the field and mountain services. Canister-shot.* A canister-shot for a gun contains 27 small cast-iron balls, arranged in four layers, the top of 6, and the remainder of 7 each. A canister-shot for a howitzer contains 48 small iron balls, in 4 layers of 12 each. For the same calibre, it will be seen that the balls used in canister-shot are smaller than those used in grape-shot. The envelope is a tin cylinder, closed at the bottom by a thick cast-iron plate, and at the top by one of sheet-iron. The plates are kept in place by cutting the edges of the cylinder into strips WIr=W about 0.5 inch long, and lapping them over the plates. To give more solidity to the mass, and prevent Fig. 13. the balls from crowding upon each other when the piece is fired, the interstices are closely packed with sawdust. The handle is made of wire, and attached to the thin plate at the top. Canister-shot are used in the field, mountain, siege, and sea-coast services. * The balls for canister for bronze rifle-guns are made of lead, or enclosed in a case of some soft material, to avoid injury to the surface of the bore. 6 82 PROJECTILES.-CASE-SHOT. It is stated that canister-shot were first used in the defence of Constantinople, about the middle of the 15th century. Xpsherical case-slhot. Though projectiles similar to spherical case-shot were used in France as early as the time of Louis XIV., the credit of perfecting them is due to Colonel Shrapnel of the British army. They were first successfully used by the English against the French, in the Peninsular war. The envelope in the spherical case-shot, is a thin castiron shell, the weight of which, when empty, is about one half that of the equivalent solid shot. To prepare this shot, it is first filled with round musket-balls,?17 to the lb., and the interstices are then filled up by pouring in melted sulphur or resin; the object of which Fig. 14. iS to solidify the mass of bullets, and prevent them from striking, by their inertia, against the sides of the case and cracking it, when the piece is fired. A hole is bored through the mass of sulphur and bullets, -to receive the bursting charge; and, in order not to displace too many bullets, and not to scatter them too far when the shot bursts, the bursting charge should only be sufficient to produce rupture. If the iron, of which the case is made, were always of suitable quality, and the cavity filled with bullets snugly packed in, there would be no necessity for sul-, phur to prevent accidents. In this case, it would not be necessary to remove any of the bullets, as the bursting charge would be disseminated through the interstices; and the difficulty, which now sometimes arises' BAR-SHOT. 83: from their adhering to fragments of the case, would be entirely obviated. To increase the effect of a small bursting charge, the lower portion of the fuze-hole, 6, fig. 14, is partially closed, by screwing into it a disk perforated with a small hole for the passage of the flame from the fuze. The spherical case-shot mostly used for field service is the 12-pounder; it contains about 80 bullets; its bursting charge is 1 oz. of powder; and it weighs when finished 11.75 lbs.,-nearly as much as a solid shot of the same calibre. The rupture of a spherical case-shot may be made to take place at any point of its flight; and in this respect it is superior to canister and grape-shot, Which begin to separate the moment they leave the piece. 47. Bar-shot. Bar-shot consist of two hemispheres, or two spheres, connected together by a bar of iron; the motion of rotation which these projectiles assume in flight, renders them useful in cutting the masts and rigging of vessels; but, as they are very inaccurate, they are only employed at short distances. They are very little used, however, at the present day. Chaic.n-shot only differ from bar-shot in the mode of connection, which is a chain, instead of a bar. 48. Percussion bullets. Percussion bullets may be made by placing a small quantity of percussion powder, enclosed in a copper envelope, in the point of an ordinary rifle-musket bullet, or by casting the bullet around a small iron tube, which is afterward filled with powder and surmounted with a common percussion-cap. lF!. 15. The impact of the bullet against a sub 84 PROJECTILES.-RUPTIJRE. stance no harder than wood is found to ignite the percussion charge or cap, and produce an effective explosion. These projectiles can be used to blow up caissons, and boxes containing ammunition, at very long distances. 49. carcasses. Carcasses are shells which have three additional holes, of the same dimensions as the fuzehole, pierced at equal distances apart in their upper hemispheres, with their exterior openings tangent to the great circle perpendicular to the axis of the fuzehole. The object of a carcass is to set fire to wooden structures, by the flame of the burning composition which issues through the holes. CHARGE OF RUPTURE OF SHELLS. 50. Plane of rupture. Suppose the cavity of the shell to be spherical, and concentric with the exterior. As soon as the enclosed charge of powder is inflamed, the gases developed expand into the cavity, and the expansive force increases until it is sufficient to over-'come the tenacity of the metal, and produce rupture; which will take place in the direction of least resistance, or following a surface composed of lines normals to the two surfaces. Let R be the radius of the exterior, and r the radius of the interior surface; o, the common centre of the two spheres; T, the tenacity of the material of which the sphere is composed; and p, the presFig. 16. sure on a unit of surface to overcome the tenacity of the metal. PLANE OF RUPTURE. 85 Let C~ be the radius of the circle of rupture on the interior surface. From the known properties of gases, the pressure exercised on the area of this circle to produce rupture is equal to the components of all the normal pressures acting on.the spherical segment of which it is the base, taken perpendicularly to the plane of this circle; therefore TrpC2 is the pressure of the gases which tends to break the sphere. Under this supposition, rupture should follow the surface of the frustum of a cone of which this circle is the smaller base. The surface of this frustum is equal to the difference of the surfaces of two cones whose common apex is at the centre of the sphere. The base of the smaller is 27C, and its slant height r; its surface therefore is equal to -rCr. The surface of the larger cone, whose generatrix is the radius of the exterior sphere, will be to the smaller as R2 is to r2, and therefore r CrJ; their difference, or the area of the surface of rupture will be equal to C/( _ —1 If the pressure of the gases acted normally to the surface of the fracture, or in the direction of the tenacity, this surface multiplied by Twould give the total resistance, which should be equal to the pressure of the gases; but it acts obliquely, and to produce rupture should be increased by a quantity which depends on the law of increase of the resistance due to the angle which the pressure makes with the normal. Although we cannot measure this resistance, it must be admitted 8 6 PROJECTILES.-RUPTURE. that the effort to overcome is greatest when the power is in the direction of the normal to the surface of rupture. We shall, therefore, have the relation, pC _TCJj 21) ~6+d Or, In this expression the value of 6 is unknown; but it is easy to be seen that it diminishes as the direction of the pressure approaches the normal, and when they coincide 6 becomes 0. At the same time C increases, and the value of Tp diminishes, until C becomes equal to r, its maximum value. Therefore, the section of easiest rupture of a hollow sphere passes through a great circle, and the pressure which is in etuiliXrio with the tenacity of the metal, will be given by the foregoing formula, by making C-_r, and =-0; it will then become, -=P 2 1( ) (2). When the pressure is less than this value of p, the sphere will resist its charge of powder; when it is greater than this value, the sphere will burst. The density of the gaseous products of the powder necessary to burst the sphere can be easily found by Rumford's formula: Atmos. p= 1.841 (905d)l+~0.62d; but d, or the density of the gaseous products, is equal LOSS OF GAS. 87 to their weight, or the weight of the bursting charge, divided by the interior space of the sphere. W Or, ~m.3' W-4'd. 3_ — - rr 51. Loss of gas by fuze-hole. This loss of force by the fuze-hole may be ascertained with sufficient accuracy, provided we know from actual experiment the amount of the loss from the fuze-hole of any one shell. Let 1R and r be the exterior and interior radii of a spherical projectile; T, the tenacity of the metal; i, the radius of the fuze-hole; wq', the weight of powder necessary to burst it under the supposition that there is: no loss of force at the fuze-hole; w, the weight of powder that is actually required to burst it. By the preceding formulas we obtain the value of w'; w-w' is therefore the amount of loss by the fuze-hole. Take another projectile, and let wA represent the charge which is necessary to burst it, under the supposition that there is no loss, and w, the weight that is found by experiment necessary to burst it; qw, —'w will represent the loss. We are at liberty to suppose the loss from the two fuze-holes is proportional to the size of the holes, and the density of the gases at the morient of rupture; we shall, therefore, have this proportion, w-w':iv,-w.j::, id i,2d,. i2d Or, w- w +(w,-w,') Od, From the experiments made at Metz in 1835, it was shown that this mode of estimating the loss of force by 88 PROJECTILES.-FABRICATION. the fuze-hole, was sufficiently exact for practical purposes. FABRICATION OF PROJECTILES. 52. lIaterials. Shot and shells should be made of gray or mottled iron, of good quality. Spherical cace-shot should be made of the best quality of iron, and with peculiar care, in order that they may not break in the gun. All projectiles should be cast in sand and not in iron moulds, as those from the latter are generally not spherical in form, nor uniform in size; they are also full of cavities, and are cracked by being heated. Sand. The sand used should be silicious, of an angular grain, and moderate degree of fineness. It should be mixed with a sufficient quantity of clay, so that, when slightly moistened, it will retain its shape when pressed in the hand. Pattern. The pattern of a spherical projectile is'composed of two hollow cast-iron hemispheres, which unite in such a manner as to form a perfect sphere; on the interior of each hemisphere is fastened a handle to enable the operator Fig. 17. to draw it from the sand when the half-mould is completed. The flakss which contain the mould are made of cast iron, in two equal parts united at their larger bases. Moulding. This operation is performed by placing the flat side of one of the hemispheres on the mouldingboard, and covering it with a flask. Sand is then PATTERN. 89 poured into the flask, filling up the entire space between it and the hemisphere, and well rammed. The flask is then turned over, the hemisphere is withdrawn, and the entire surface of the sand painted with coke-wash, and dried. The remaining half of the mould is formed in the same way, except that a channel for the introduction of the melted iron is made by inserting a round stick in the sand before it is rammed, and withdrawing it afterward. To secure strong metal and a homogeneous casting for large size solid shot, they are cast in a string, one above the other, with a large sinking head and connecting branches. They are afterwards cut apart and turned down to the required shape and size. Three 20-inch and four 15-inch shot may be cast in this manner. Hollow projectiles. Thus far, the operation of moulding and casting solid and hollow projectiles are the same. The cavity of a hollow projectile is made by inserting a core of sand, which is formed around a stem fastened into the lower half of the mould. The stem is hollow, and perforated with small holes to allow of the escape of steam and gas generated by the heat of the melted Imetal. It is also made of iron, but that part of it which comes in contact with the melted iron,, and forms the fuze-hole, is coated with sand. In pouring the melted iron into the mould with the ladle, care should be taken to prevent scoria and dirt from entering with it; and, for this purpose, the surface should be skimmed with a wooden stick. Before the iron is fairly cooled, the flasks are opened, and the sand knocked from the castings. After this, the core is broken up and knocked out, and the interior surface cleaned by a scraper. The sinking head 90 PROJECTILES.- INSPECTION. and other excrescences are knocked off, and the surface smoothed in a rolling-barrel, or with a file, or chisel, if necessary. The fuze-hole is then reamed out to the proper size, and the projectile is ready for inspection. INSPECTION OF PROJECTILES. 53. Object of inspection. The principal points to be observed in inspecting shot and shells are, to see that they are of proper size in all their parts; that they are made of suitable metal; and that they have no defects, concealed or otherwise, which will endanger their use, or impair the accuracy of their fire.' As it would be impracticable to make all projectiles of exact dimensions, certain variations are allowed in the fabrication. See Ordnance Manual. Inspection of shot. The instruments are one large and one small gauge, and one cylinder gauge; the cylinder gauge has the same diameter as the large gauge, it,is made of cast iron, and is five calibres long. There are also, one hammer with a conical point, six steel punches, and one searcher made of wire. The shot should be inspected before they become rusty; after being well cleaned, each shot is placed on a table and examined by the eye to see that its surface is smooth, and that the metal is sound and free from seams, flaws, and blisters. If cavities or small holes appear on the surface, strike the point of the hammer or punch into them, and ascertain their depth with the searcher; if the depth of the cavity exceed 0.2 inch, the shot is rejected; and also if it appear that an attempt has been made to conceal such defects by filling them up with nails, cement, &c. INSPECTION. 91 The shot must pass in every direction through the large gauge, and not at all through the small one; the founder should endeavor to bring the shot up as near as possible to the large gauge, or to the true diameter. After having been thus examined, the shot are passed through the cylinder gauge, which is placed in an inclined position, and turned from time to time, to prevent its being worn into furrows; shot which slide or st6ick in the cylinder are rejected. Shot are proved by dropping them from a height of twenty feet on a block of iron, or rolling them down an inclined plane of that height, against another shot at the bottom of the plane. The average weight of the shot is deduced from that of three parcels of twenty to fifty each, taken indiscriminately from the pile; some of those which appear to be the smallest should also be weighed, and they are rejected if they fall short of the weight expressed by their calibre, more than one thirty-second part. They almost invariably exceed that weight. Insp~ection of gra)e and canister shot. The dimensions are verified by means of a large and small gauge, attached to the same handle. The surface of the shot should be smooth, and free from seams. I~spection of hollow projectiles. The inspecting instruments are a large and snall gauge for each calibre, and a cylinder gauge for shells of eight inches and under. Cali2)ers for measuring the thickness of shells at the sides. Ccalipers to measure the thickness at the bottom. 92 PROJECTILES.-INSPECTION. Gctuges to verify the dimensions of the fuze-hole, and the thickness of the metal at the fuze-hole. A lpair of hand-6ellows, a wooden plug to fit the fuze-hole, and bored through to receive the nozzle of the bellows. A -hammer; a searcher; a cold chisiel, steel punches. Inspection. The surface of the shell and its exterior dimensions, are examined as in the case of shot. The shell is next struck with the hammer, to judge by the sound whether it is free from cracks; the position and dimensions of the ears are verified; the thickness of the metal is then measured at several points on the great circle perpendicular to the axis of the fuze-hole. The diameter of the fuze-hole, which should be accurately reamed, is then verified, and the soundness of the metal about the inside of the hole is ascertained by inserting the finger. The shell is now placed on a trivet, in a tub containing water deep enough to cover it nearly to the fuzehole; the bellows and plug are inserted into the fuzehole, and the air forced into the shell; if there be any.holes in the shell, the air will rise in bubbles through the water. This test gives another indication of the soundness of the metal, as the parts containing cavities will dry more slowly than other parts. The mean weight of shells is ascertained in the same manner as that of shot. Shot and shells rejected in the inspection, are marked with an X made with a cold chisel-on shot near the gate, and on shells near the fuze-hole. PRESERVATION.-PILING.:93 PRESERVATION AND PILING OF BALLS. 54. Lackering. Projectiles should be carefully lackered as soon as possible after they are received. When it is necessary to renew the lacker, the old lacker should be removed by rolling or scraping the balls, which should never be heated for that purpose. UPiling. Balls should be piled according to kind and calibre, under cover if practicable, in a place where there is a free circulation of air; to facilitate which, the piles should be narrow if the locality permits; the width of the bottom tier may be from twelve to fourteen balls, according to the calibre. Prepare the ground for the base of the pile by raising it above the level of the- surrounding ground, so as to throw off the water; level it, ram it well, and cover it with a layer of screened sand. Make the bottom of the pile with a tier of unserviceable balls, buried about two-thirds of their diameter in the sand; this base may be made permanent; clean the base well, and form the pile, putting the fuze-holes of the shells downward, in the iznterals, and not resting on the shells below. The base may be also made of bricks, concrete, stone, or with borders and braces of iron. 55. To find the number of balls in a pile. Au[ltily thae sum of the nunzber of balls in the three parallel edges by one-third of the number in a triangulcr face. In a square pile, one of the parallel edges contains but one ball; in a triangular pile, two of the edges have but one ball in each. 94 PROJECTILES. -ROCKETS. The number of balls in a triangular face is n being the number in the bottom row. The sum of the three parallel edges in a triangular pile is n+2; in a square pile, 2n+1; in an oblong pile, 3N+2n-2; Nbeing the length of the top row, and n the width of the bottom tier; or 3m —n+1; rn being the length, and n the width of the bottom tier. If a pile consist of two joined at right angles, calculate the contents of one as a common pile, and the other as a pile of which three parallel edges are equal. THEORY AND CONSTRUCTION OF ROCKETS. 56. Structure. A rocket is a projectile which is set in motion by a force residing within itself; it therefore performs the two-fold function of piece and projectile. It is essentially composed of a strong case of paper or wrought iron, enclosing a composition of nitre,..-chamcoal, and, suph'r —the same as gunpowder, except that the.ingredients are proportioned for a slower rate of combustion. If penetration and range be required, its head is surmounted by a solqid shot; if explosion and incendiary effect, by a shell or spherical case-shot, to which is attached a fuze, which is set on fire when it is reached by the flame of the burning composition. The base is perforated by one or more vents for the escape of the gas generated within, and sometimes with a screw-hole to which a guide-stick is fastened. The disposition of the different parts will be readily understood by reference to the subjoined figure, which MOTION. 95 represents a section through the long axis of a Congreve rocket. Fig. 18. 57. notion. A rocket is set in motion by the reaction of a rapid stream of gas escaping through its vents.'If'it be surrounded by a resisting medium, the atmosphere for instance, the particles of gas, as they issue from the vent, will impinge against and set in motion certain particles of air, and the force expended on the inertia of these particles will react and increase the propelling force of the rocket. It follows, therefore, that, though, a rocket will move in vacuo, its propelling force will be increased by the presence of a resisting medium. Whether the effect will be to accelerate the rocket depends upon. the relation between the resistance which the medium offers to the motion of the gas, and that which it offers to the motion of the rocket. Vent. As the rate of combustion of the composition is independent of the pressure of the gas in the bore, it follows, that if the size of the vent be contracted, the flow of gas through it will be accelerated. The strength' of the case, and the friction of the gas, which increases as the vent diminishes, alone limit the reduction of the size of the vent. For vents of the same size, but of different shapes, that one which allows the gas to escape most freely, will be most favorable to the flight of the rocket. A conical form of vent, with the larger orifice next to the bore, will allow the gas to escape more rapidly than 96 PROJECTILES.-ROCKETS. one of cylindrical form. This may be shown by burn. ing portfire composition in tubes with different-shaped vents. It will be found that the sparks from a conical vent will be thrown much higher than those from a cylindrical vent; the relative heights depending on the slope of the sides of the conical vent. Bore. As the composition of a rocket burns in parallel layers of uniform thickness, the amount of gas generated in a given time, or the velocity of its exit from the case, depends on the extent of the inflamed surface. Experience shows that to obtain the required surface of inflammation, it is necessary to form a long cavity in the mass of the composition. This cavity is called the 6ore. In small rockets, the bore is formed by driving the composition around a spindle which is afterward withdrawn; but in the large ones, the composition is driven into the case in a solid mass by a powerful hydrostatic press, and then bored out with a bit. In all rockets the bore should be concentric with the case; its shape should be made conical to facilitate the drawing out of the spindle, and to diminish the strain on the case near its head, by reducing the amount of surface where the pressure on the unit of surface is greatest. - VNature of movement. Suppose the rocket in a state of rest, and the composition ignited; the flame immediately spreads over the surface of the bore, forming gas, which issues from the vent. The escape is slow in the first moments, as the density of the gas is slight; but as the surface of the inflammation is large compared to the size of the vent, the gas accumulates rapidly, and its density is increased until the velocity of the escape GUIDING PRINCIPLE. 97 is sufficient to overcome the resistances which the rocket offers to motion. These resistances are, inertia, friction, the component of weight in the direction of motion, and, after motion takes place, the resistance of the air. The constant pressure on the head of the bore accelerates the motion of the rocket until the resistance of the air equals the propelling force; after this, it will remain constant until the burning surface is sensibly diminished. When the gas ceases to flow, the rocket loses its distinctive character, and becomes, so far as its movement is concerned, an ordinary projectile. The increase in the surface of combustion whereby,more gas is developed in the same time, and the diminution in the weight of the remaining composition,.cause the point of maximum velocity to be reached with increased rapidity. If the weight of the rocket be increased, the instant of maximum velocity will be prolonged, but the amount will remain the same. A change in the form of the rocket which increases the resistance of the air, will have the effect to diminish the maximum velocity. The maximum velocity of French rockets, and the distances at which they are attained, are given in the following table:CALIBRE. DISTANCE. MAXM. VELOCITY. 2- inches, 134 yds. 278 yds. 23 " 141 " 370 " According to the calculations of Piobert, for small rockets it takes about 3- second for the gas to attain its maximum velocity of 850 yds. 58. Guiding principle. The propelling force of a. 7 98 PROJECTILES. — ROCKETS. rocket changes its direction with the axis along which it acts; it follows, therefore, that without some means of giving stability to this axis, the path described will be very irregular, so much so, at times, as to fold upon itself; and instances have been known where these projectiles have returned to the point whence they started. An example of this irregular motion may be seen in "serpents," a species of small rockets without guidesticks. The two means now used to give steadiness to the flight of a rocket are, rotation, as in the case of a rifleball, and the'resistance of the air, as in an arrow. Hale'8 8system. The first is exemplified in Hale's rocket, where rotation is produced around the long axis by the escape of the gas through five small vents situated obliquely to it. In his first arrangement, the inventor placed the small vents in the base, surrounding the large central vent, so that the resultant of the tangential forces acted around the posterior extremity of the axis of rotation. In 1855, this arrangement was changed by reducing the number of the small vents to'three, and placing them at the base of the head of the rocket. The rocket thus modified, and shown in fig. 20, is the one now used by the United States government for war purposes.* * A still later improvement in Hale's rocket consists in screwing a cast-iron piece (a) into the bottom of the case, which is perforated with three vents. A corresponding side of each (ga 0 _ 7,vent is sur-........... rounded with a fence (b. b. b.), Fig. 19. the opposite sides being open. The gas in its efforts to expand after issuing from the vents, presses against the fences and rotates the rocket around its long axis. HOW FIRED. 99 Fig. 20. a.. Bore and vent. c..Tangential vent (three). b..Recess in the base of the head. d. Head (solid). Conjreve'8 s8ystem. A Congreve rocket is guided by a long wooden stick attached to its base. If any cause act to turn it from its proper direction, it will be opposed by resistances equal to its moment of inertia and the lateral action of the air against the stick. The effect of these resistances will be increased by placing the centre of gravity near the head of the rocket, and by increasing the surface of the stick. In signalc rockets, where the case is made of paper, the stick is attached to the side by wrapping around twine; and there is but one large vent, which is in the centre of the case. In war-rockets the stick is attached to the centre of the base, and the large central vent is replaced by several small ones near its circumference. See fig. 18. The former arrangement is not so favorable to accuracy as the latter, inasmuch as rotation will be produced if the force of propulsion and the resistance of the air do not act in the same line. 59. How fired. Rockets are generally fired from tubes or gutters; but should occasion require it, they may be fired directly from the ground, care being taken to raise the forward end by propping it up with a stick or stone. As the motion is slow in the first moments of its flight, it is more liable to be deviated from its 100 PROJECTILES. -ROCKETS. proper direction at this time than any other; for this reason the conducting tube should be as long as practicable, say from five to ten feet.* 60. Form of trajectory. Take that portion of the /trajectory where the velocity is uniform. The weight of the rocket applied at its centre of gravity, and acting in a vertical direction, and the propelling force acting in the direction of its length, are two forces the oblique resultant of which moves the rocket parallel to itself; but the resistance of the air is oblique to this direction, and acting at the centre of figure, a point situated between the centre of gravity and extremity of the guidestick, produces a rotation which raises the stick, and thereby changes the direction in which the gas acts. As these forces are constantly acting, it follows that each element of the trajectory has less inclination to the horizon than the element of an ordinary trajectory in which the velocity is equal. When the velocity is not uniform, the position of the centre of gravity has a certain influence on the form of the trajectory. To understand this, it is necessary to'consider that the component of-the resistance of the air which acts on the head of the rocket is greater than that which acts on the side of the stick. It is also necessary to consider that the pressure of the inflamed gas acts in a direction opposite to the resistance of the air, that is to say, from the rear to the front, and that the centre of gravity is near the rear extremity of the case. * Mr. Hale has suggested a means of using a short tube, by applying a pressure to the rocket to retain it in its place until the gas has acquired the requisite velocity. FORM OF TRAJECTORY. 101 At the beginning of the trajectory, when the motion of the rocket.is accelerated, its inertia is opposed to motion, and being applied at the centre of gravity, which is in rear of the vent, the point of application of the moving force, it acts to prevent the rocket from turning over in its flight. But when the composition is consumed, the centre of gravity is thrown further to the rear, and the velocity of the rocket is retarded, the inertia acts in the opposite direction, and the effect will be, if the centre of gravity or inertia is sufficiently far to the rear, to cause it to turn over in the direction of its length. If the rocket be directed toward the earth, this turning over will be counteracted by the acceleration of velocity due to the weight, and the form of the trajectory will be preserved. Effect of wind. When the wind acts obliquely to the plane of fire, its component perpendicular to this plane, acting at the centre of figure, will cause the rocket to rotate around its centre of gravity. As the centre of figure is situated in rear of the centre of gravity, the jioint will be thrown toward the wind, and the propelling force acting always in the direction of the axis, the rocket will be urged toward the direction of the wind. To make an allowance for the wind, in firing rockets, they should be pointed toward the opposite side from which the wind comes, or with the wind instead of against it. If the wind act in the plane of fire from front to rear, it will have the effect to depress the point, and with it the elements of the trajectory in the ascending branch, and elevate them in the descending branch; as 102 PROJECTILES. —ROCKETS. the latter is shorter than the former, the effect of a front wind will be to diminish the range. The converse will be true for a rear wind. 61. History. Rockets were used in India and China for war purposes before the discovery of gunpowder; some writers fix the date of their invention about the close of the ninth century. Their inferior force and accuracy limited the sphere of their operations to incendiary purposes, until the year 1804, when Sir William Congreve turned his attention to their improvement. This officer substituted sheet-iron cases for those made of paper, which enabled him to use a more powerful composition; he made the guide-stick shorter and lighter, and removed a source of inaccuracy of flight by attaching the stick to the centre of the base instead of the side of the case. He states that he was enabled by his improvements to increase the range of 6-pdr. rockets from 600 to 2,000 yards. Under his direction they were prepared, and used successfully at the siege of Boulogne and the battle of Leipsic. At the latter place they were served by a special corps. 62. Advantages. The advantages claimed for rockets over cannon are, unlimited size of projectile; portability; freedom from recoil; rapidity of discharge; and the terror which their noise and fiery trail produce on mounted troops. The numerous conditions to be fulfilled in their con. struction in order to obtain accuracy of flight, and the uncertainty of preserving the composition uninjured for a length of time, are difficulties not yet entirely overcome, and which have much restricted their usefulness for general military purposes. RIND USED. 103 63. Kind used. The two sizes of Hale's rockets in use in the American service are, the 2-inch (interior diameter of case), weighing 6 lbs.; and 3-inch " " " " 16 lbs. Under an angle of from 40 to 50 the range of these rockets is from 500 to 600 yds. Under an angle of 47~ the range of the former is 1,760 yds. and the latter 2,200. 104 CANNON. CHAPTER III. HISTORY OF CANNON. 64. THE terms cannon and ordnance are applied to all heavy fire-arms which are discharged from carriages, in contradistinction to emall-arms, which are discharged from the hand. 65. Early cannon.* The MORTAR. shape of the first cannon used, after the invention of gunpow-, -i: >.: der was conical, internally and externally resembling an / 2/ / / / / apothecary's mortar. They Fig. 21. were called qnortars, bomzbards and vaqes; were fired at high angles; and, in conseBOMBARD. quence of the slow Ar\\Zght-ba1ls, tarred links, pitchedfascines, and torches. * In the British sea-coast service shells are used, for incendiary purposes by filling them with molten iron drawn from a small cupola furnace. If the shell be broken on striking, the hot iron is scattered about; if it be not broken, the heat penetrates through the shell with sufficient intensity to set wood on fire. FIRE-BALL. 3733 382. Fire-ball. A fire-ball is an oval-shaped canvas sack, filled with combustible composition (fig. 130). It is intended to be thrown from a mortar to light up the works of an enemy, and is loaded with a shell to prevent it from being approached and extinguished. Sack. The sack is made of sail-cloth, cut into three oval pieces or gores, and Fig. 13U0. sewed together at their edges. Several thicknesses of cloth may be used, if necessary. One end of the sack is left open, and, after being sewed, it is turned to bring the seam on the inside. Corn2osition. The composition for a fire-ball consists ofNITRE. SULPHUR. ANTIMONY. ~8 ~ 2 11 After being pulverized, mixed, and sifted, the composition is moistened. with one-thirtieth of its weight of water, and again passed through a coarse sieve. The ball is filled by pouring a layer of composition into the sack, and placing the shell (fuze down) upon it; after this, the composition is well rammed around and above the shell, and the sack is closed at the top. Fisni8inqg. The bottom of the sack is protected from the force of the charge by an iron cup (a), called a culot, and the whole is covered and strengthened with a network of spun-yarn, or wire, and then overlaid with a composition of pitch, rosin, &c. 374 PYROTECHNY.-FIREWVORKS FOR LIGHT. Afire-ball is primed by driving into the, top of the composition a greased wooden pin about three inches deep, and filling the hole thus formed with fuze composition, driven as in a fuze; space is left at the top of each hole for two strands of quick-match, which are fastened by driving the composition upon them. The fuze-hole is covered with a patch saturated with kit composition, which is a mixture of rosin, beeswax, pitch, and tallow. 383. Light-ball. Light-balls are made in the same manner as fire-balls, except that, being used to light up our own works, the shell is omitted. 384. Tarred links, Tarred links are used for lighting up a rampart, defile, &c., or for incendiary purposes. They consist of coils of soft rope, placed on top of each other, and loosely tied together; the exterior diameter of the coil is 6 inches, and the interior 3 inches. They are immersed for about ten minutes in a composition of 20 parts of pitch, and one of tallow, and then shaped under water; when dry, they are plunged in a composition of equal parts of pitch and ro&in, and rolled in tow or saw-.dust. To prevent the composition from sticking to the hands, they should be previously covered with linseed oil. How used. Two links are put into a rampart grate, separated by shavings. They burn one hour in calm weather, and half an hour in a high wind, and are not extinguished by rain. To light up a defile, the links are placed about 250 feet apart; to light up a march, the men who carry the grates should be placed to the leeward of the column, and about 300 feet apart. 385. Pitched fascines. Fagots of vine-gvigs, or other TORCHEs. 315 very combustible wood, about 20 in. long and 4 in. diameter, tied in three places with iron wire, may be treated in the same manner, and used for the same purposes as links. The incendiary properties of pitched fascines may be increased by dipping the ends in melted rockfire; when used for this purpose, they are placed in piles intermingled with shavings, quick-match, bits of port-fires, &c., in order that the Whole may take fire at once. 386. Torches. A torch is a ball of rope impregnated with an inflammable composition, and is fastened to the end of a stick, which is carried in the hand. Preparcation. Old rope, or slow-match, well beaten and untwisted, is boiled in a solution of equal parts of water and nitre; after it is dry, tie three or four pieces (each four feet long) around the end of a pine stick, about two inches diameter, and four feet long; cover the whole with a mixture of equal parts of sulphur and mealed powder, moistened with brandy, and fill the intervals between the cords with a paste of three parts of sulphur and one of quicklime. When it is dry, cover-the whole with the following composition: PITCH. VENICE TURPENTINE. TURPENTINE. 3 _2 How used. Torches are lighted at the top, which is cracked with a mallet; they burn from one and a quarter to two hours. In lighting the march of a column, the men who carry torches should be about 100 feet apart. 376 PYROTECHNY. —OFFE NSIVE; ETC., FIREWORKS. OFFENSIVE AND DEFENSIVE FIREWORKS. The principal preparations of this class, employed in modern warfare, are bags of powder and light-barrel8s. 387. Bags of powder. Bags or cases of powder may be used to blow down gates, stockades, or form breaches in thin walls. The fJetard was formerly employed for these purposes, but it is now generally thrown aside. From trials made in England, it has been shown that a sand-bag (covered with tar, and sanded to prevent it from sticking) containing 50 lbs. of powder, has, sufficient force to blow down a gate formed of 4-inch oak scantling, and supported by posts 10 inches in diameter, and 8 feet apart; and a bag containing 60 lbs. of powder, and weighted with two or three bags of earth, has sufficient force to make a large hole in a 14-inch brick wall. The effect of the explosion may be much increased by making three sides of the bag of leather, and the fourth of canvas, which should rest against the object. A suitable means of exploding bags of -powder is a timefuaze, or the ordinary 8afety-fuze for blasting rocks. 388. Light-barrel. A light-barrel is a common powder-barrel pierced with numerous holes, and filled with shavings that have been soaked in a composition of pitch and rosin; it serves to light up a breach, or the bottom of a ditch. ORNAMENTAL FIREWORKS. 389. Object, &c. Ornamental fireworks are employed GERBE. 377 to celebrate great events, as victories, treaties of peace, funerals, &c. They are divided intofixed pieces, mnovable pieces, decorative pieces, and preparations for communicating fire from one part of a piece to another. The different effects are produced by modifying the proportions of the ingredients of the burning composition, so as to quicken or retard combustion, or by introducing substances that give color and brilliancy to the flame. The fixed pieces are lances,petards, gerbes, flames, &c. 390. Lance. Lances are small paper tubes from 0.2 to 0.4 in. diameter, filled with a composition which emits a brilliant light in burning (a, fig. 131). Instead of a single composition, each lance may contain two or more Fig. 131. compositions, which, in turn, emit different-colored flames. The case should be as thin as possible, in order that the color of the flame of the composition may not be affected by that of the paper. Lances are generally employed to form figures; this is done by dipping one end in glue, and sticking them in holes arranged after a certain design, in a piece of wood-work. 391. Petard. Petards are small paper cartridges filled with powder. One end is entirely choked, and the other is left partially open for the passage of a strand of quick-match, destined to set fire to the powder. A petard is usually placed at the fixed end of a lance, that the flame may terminate with an explosion (b, fig. 131); they are also used to imitate the fire of mus-.ketry. 392. Gerbe. Gerbes are strong paper tubes or cases, filled with a burning composition. The ends are tamped 378 PYROTECHNY.-MOVABLE PIECES. with moist plaster of Paris or clay; through one, a hole is bored, extending a short distance into the composition, that it may emit a long sheaf or ger6e of brilliant sparks. The diameter of the case is about one inch, and the length depends upon the required time of burning. The number of blows to each ladleful of composition is ten. Gerbes are secured to the frame of the piece with wire or strong twine, and pointed in the direction that the flame is to take. Comnposition. CAST-IRON FILINGS MEALED POWDER. NITRE. SULPHUR. MIXED WITH SULPHUR. 32 16 10 26.4 393. iFame. Flames consist of lance or star composition, driven into paper cases or earthen vases. The diameter of the burning surface should be large, to give.intensity to the flame. Lance composition is driven dry, and with slight pressure. Star composition should be moistened, and driven with greater pressure than the preceding. MOVABLE PIECES. The movable pieces are.s.ky-irockets, tourbillion s,,saxons, jets, Roman candles, paper selles, &c. 394. Sky-rocket. Sky-rockets are the same as the signal-rockets before described, except that the com JETS. 379 position is arranged to give out a more brilliant train of fire. Composition. MEALED POWDER. NITRE. SULPHUR. CAST-IRON FILINGS. 122 80 40 40 395. Tourbillion. The tourbillion is a case filled with sky-rocket composition, and which moves -with an upward spiral motion. The spiral motion is produced by six holes-two lateral holes (one on each side), for the rotary motion, and four on the under side, for the upward motion. It is steadied by two wings formed by attaching a piece of a hoop to the middle of the case, and at right angles to its length. To give it a proper initial direction, a hole is made through the centre of the case to' fit on a vertical spindle, which is fastened to an upright post. 396. Saxon. The saxon is the same as the tourbillion, except that it is only pierced with the central and two lateral holes, and has no wings. The central hole is placed on a horizontal spindle, and the piece has the appearance of a revolving sun. 397. Jets. Jets are rocket-cases filled with a burning composition; they are attached to the circumference of a wheel, or the end of a movable arm, to set it in motion. They also produce the effect of gerbes; and to increase the circle of fire, they are inclined to the radius at an angle of 20~ or 30~. 380 PYROTECHNY.-MOVABLE PIECES. Compos8ition. MEALED POWDER. NITRE. SULPHUR. CAST-IRON FILINGS. 50 36.5 15 24.6 398. Roman candles. A Roman candle is a strong paper tube containing stars, which are successively thrown out by a small charge of powder placed under each star. A slow-burning composition is placed over each star to prevent all of them from taking fire at once. Slow Composition. MEALED POWDER. CHARCOAL. 2 1 1 399. Paper shell. This piece is a paper shell filled with decorative pieces, and fired from a common mortar. It contains a small bursting-charge of powder, and has a fuze regulated to ignite it when the shell reaches the summit of its trajectory. The shell is made by pasting several layers of thick paper over a sphere of wood, cutting the covering thus formed in halves, so as to remove the sphere, joining the halves again, and pasting paper over them until the thickness is sufficient to resist the charge of the mortar. 400. Decorative pieces. Decorative pieces are stavrs, serpents, marrons, &c., described under the head of rockets. 401. For communicating fire. Preparations for com GENE1RALI REARKM. 3S1 municating fire from one piece to another are quick.match, leaders, port-ires8, and mortar fuezs. The leader is a thin paper tube containing a strand of quick-match, and it is united to a piece by pasting pieces of paper over the joint. If the piece is to be fired at once, the leader may be omitted, and strands of quickmatch tied together used in its place. 402. General remark. The foregoing pieces are generally mounted on pieces or frames of light wood, and are susceptible of being combined so as to produce a great variety of striking effects. 38 2 SCIENCE OF GUNNERY. PART II. CHAPTER VIII. SCIENCE OF GUNNERY. THE science of gunnery treats of the motion of projectiles, and of their effects. Ballistics is that branch of the science of gunnery which treats of the motion of projectiles. 403. History of ballistics. Ancient artillerists considered that the trajectory, or path described by a projectile after it left its piece, was composed of three distinct parts:- 1st. The violent, which approached a straight line. 2d. The middle, or mixed, which was a circle. 3d. The last, or natural, which was also a right line. Tartaglia, an Italian engineer, invented the quadrant. for measuring elevations, which he divided into twelve parts, and by which he was able to compare the ranges of different cannon, fired under the same or different degrees of elevation. He demonstrated that no portion of the trajectory was a right line, and that the angle which gave the greatest range was 45~. Galileo. About 1638, Galileo discovered the laws which govern the fall of bodies, and from tlhese he demonstrated that the curve described by a projectile, thrown in a direction oblique to the horizon, is a parabola, the axis of which is vertical. He did not con FUNDAMENTAL QUESTIONS. 383 sider that the air offered any material resistance to the motion of artillery projectiles. Newton. About 1723, Newton demonstrated that the curve described by a spherical projectile in the air, was far from being a parabola; that the two branches were dissimilar, and that the descending branch would become vertical if sufficiently prolonged. While he considered the resistance of the air proportioned to the square of the velocity, he did not conceal the fact that this was but an approximation to the true relation, which remained to be determined by experiment. Robins. About 1765, Robins invented an instrument for determining the initial velocity of a projectile, called the ballistic pendulum, by which he was able to show that the range in vacuo was much greater than in air. He also discovered that the rotary motion which spherical projectiles generally assume around their centres of gravity, will cause them to deviate from their true direction. Hutton. Hutton, who lived about the beginning of the present century, improved the ballistic pendulum, and applied it to determine the true law of the resistance of the air, as exemplified in projectiles of small' calibre. At Metz, in 1839 and'40, further experiments weremade on the resistance of the air to projectiles of large size, moving with high velocities, and the law of variation was determined with great accuracy. INITIAL VELOCITY. 404. Fundamental questions. The subject of ballis 384 SCIENCE OF GUNNERY.-INITIAL VELOCITY. tics presents two fundamental questions: 1st. To determine the initial velocity of a projectile for a known piece and. charge of powder. 2d. Knowing the initial velocity and angle of projection, to determine the range, time of flight, remaining velocity, and, in fact, all the circumstances of the projectile's motion. 405. Definition of velocities. The velocity of a projectile, at any point of its flight, is the space in feet, passed over in a second of time, with a continuous, uniform motion. Initial velocity is the velocity at the muzzle of the piece; remaining velocity is the velocity at any point of the flight; terminal velocity is the velocity with which it strikes- its object; and final velocity of descent in air, is the uniform velocity with which a projectile moves, when the resistance of the air becomes equal to the accelerating force of gravity. The initial velocity of a projectile may be determined by the principles of mechanics which govern the action of the powder, the resistance of the projectile, &c., or by direct experiment. 406. By mechanical principles. The instant that the charge of a fire-arm is converted into gas, it exerts an expansive effort which acts to drive the projectile out of the bore. If the gaseous mass be divided into elementary sections perpendicular to its length, it will be seen that, in their efforts to expand, each section has not only to overcome its own inertia, but the inertia of the piece and projectile, as well as the inertia of the sections which precede it. The tension of each section, therefore, increases from the extremities of the charge to some intermediate point where it is a maximum. The pressure on all sides of the section of maximum density -PRACTICAL RULE FOR INITIAL VELOCITY. -385 being equal, it will remain at rest, while all the others will move in opposite directions, constantly pressing against the projectile and piece, and accelerating their velocities. As the projectile moves in the bore, the space, in which the gases expand is increased, while their density is diminished; it follows that the force which sets a projectile in motion in a fire-arm varies from several causes; 1st. It varies as the space behind the projectile increases, or as the velocity regarded as a function of the time; 2d. It varies throughout the column of gas for the same instant of time; and 3d. It varies from the increasing quantities of gas developed' in the successive instants of the combustion of the powder. Piobert has made the movement of a projectile in a' fire-arm the subject of a very elaborate analytical investigation, based on the mechanical principles of the conservation of the motion of the centre of gravity, living forces, and Rumford's formula for the relation between the density and pressure of fired gunpowder. Formulazfor initial velocity. By supposing the weight of the projectile to be nothing, compared to that of the piece and carriage combined, that the tension of the gases is proportional to the density, that the length of the bore is sufficient for the entire charge to be converted into gas, and that the projectile has no windage, the elaborate equations of Piobert may be reduced to m -+ logA g; in which V is the initial velocity, X a constant to be determined by experiment, m the weight of the powder, a 25 386 SCIENCE OF GUNNERY.-INITIAL VELOCITY. the weight of the projectile, and X3 the weight of powder (loose) which would fill the bore. The above value of Y should be diminished for the loss arising from windage; the loss of force from windage is directly proportional to the space between the. bore and projectile, and inversely as the area of the bore. Hence we have w 2_X2 C22 in which A is a constant to be determined by experiment, C is the radius of the bore, and R the radius of the projectile. For ordinary windage this may be replaced by W C/ in which W is the windage, and the general expression for the initial velocity becomes V / log._. There are three unknown quantities in this equation; VF, x, and a; V can be determined by direct experiment for two or more charges of powder, and projectiles, giving two equations containing the remaining unknown quantities x and A. According to the experiments made at the Washington arsenal with the ballistic pendulum, the mean values of the co-efficients X and a, for Dupont's powder in guns of various calibres (from 6-pdr. to 32-pdr.) are: 3- 3500 feet, and = 3200 feet. XA is equal to the gravimetric density of the powder (referred to pounds and inches) multiplied by the vol. ume of the bore. WHAT AFFECTS INITIAL VELOCITY. 387 Excample. What is the initial velocity of a 6-pdr. shot fired with a service-charge? m=1.25 lbs.; p=6.25 lbs.; C=1.83 in; W=.09 in.; length of bore, 57.5 in.; weight of a cubic inch of powder, 0.0293 lbs. 1.25 17.82.09 -V=3500 / -36 25+42' log — 3200 -=1444. ft. 6 j.425 log1.25 1.83 The mean of 11 fires with the 6-pdr. gun pendulum at West Point, in November, 1860, was 1436.5 feet. 407. Practical rule for initial velocity. For the ordinary purposes of practice, where the weight of the powder and projectile alone vary, initial velocities may be considered as directly proportional to the square root of the weight of powder divided by the eqquare root of the weight of the projectile; or __.' v_v_ mv 4V r rn 4p- /' 4~/m When V is known for a given charge of powder p' and projectile mi, the value of V can be obtained for any other charge of powder, p, and projectile, m, of the same calibre. This law however only holds true within certain limits, or when the powder is completely consumed before the projectile leaves the piece.* 408. What affects initial velocity. The principal * Table of Initial Velocities with service charges. CHARGE KIND OF PROJECTILE. KIND OF CANNON. OF POWDER. SHOT. SHELLS. SPH L CASE. Lbs. Feet. Feet. Feet. 6-pdr. field l................ 1.25 1439 1357 12-pdr... 2.50 1486 1486 12-pdr. " howitzer,..1.00 1054 953 6.00 1680 1670 24-pdr. siege-gun,........ oo 18 8-inch siege howitzer,....... 4.600 907 32-pdr. sea-coast gun............ 8.00 1640 1450 15-inch columbiad............... 40.00 1000 NOTE.-When the initial velocities of shot, shells, and spherical-case shot are given, the weight of the charge refers to the solid shot. 388 SCIENCE OF GUNNERY.-INITIAL VELOCITY. causes which influence initial velocity,'are the character of the piece, powder, and projectile. Most of these have been considered under their appropriate heads, in treating of the construction of cannon; it will only be necessary, therefore, to recapitulate them here. They are the size and position of the vent, the windage, the length of the bore, the form of the chamber, the diameter and density of the projectile, the windage of the cartridge, and the form, size, density, and dryness of the grains of powder, and the barometric, thermometric, and hygrometric states of the atmosphere. It has been found by late experiments that the initial velocity is unaffected by the angle of fire. Theoretically, varying the weight of the piece should exert an influence on the initial velocity; but, in consequence of the great disparity of the weight of the piece and projectile, this influence is inappreciable in practice. 409. Determination of initial velocity by experiment. A great variety of instruments have been invented to determine directly the initial velocity of a projectile, the most reliable of which are the gun-penclulum, the ball8stic?pendulum, and the electro-bcallitic rnachines. In the first, the velocity of the projectile is determined by suspending the piece as a pendulum, and measuring the recoil impressed on it by the discharge; the expression for the velocity is deduced from the fact, that the quantity of motion communicated to the pendulum is equal to that communicated to the projectile, charge of powder, and the air. The second apparatus is a pendulum, the bob of which is made strong and heavy, to receive the impact of the projectile; and the expression for the velocity of the projectile is deduced from the THE WEST POINT BALLISTIC MACHINE., 389 fact, that the quantity of motion of the projectile before impact is equal to that of the pendulum and projectile after impact. These machines have been carried to great perfection, both in this country and France, and very accurate and important results have been obtained by them; but they are very expensive, and cannot be easily adapted to the various wants of the service. The employment of electricity to determine the velocity of projectiles, was first suggested by Wheatstone, in 1840. The application depends on the very great velocity of electricity, which, for short distances, may be considered instantaneous. The general method of applying this agent is by means of galvanic currents, or wires, supported on target frames, placed in the path of the projectile, and communicating with a delicate timekeeper. The successive ruptures of the wires mark on the time-keeper the instant that the projectile passes each wire, and knowing the distances.of the wires apart, the mean velocities, or velocities at the middle points, can be obtained by the relation, velocity-=space tilme The various plans in use differ only in the manner of recording and keeping the time of flight; one of the simplest and most common instruments employed is the pendulum. The ballistic machine of Captain Navez, of the Belgian service, has been tried in this country, but has been found too delicate and complicated for general purposes. * In consequence of the variable nature of the resistance of the air, this mean velocity does not strictly correspond to the middle point between the targets. The difference, however, is very slight, as is shown by Captain Nav6z in the case of a 6-pdr. ball moving with an initial velocity of 600 meters, over a space of 50 meters; the difference between the mean velocity and the velocity which it should have at the' middle point, is only 0.05 meter. 390 SCIENCE OF GUNNERY.-INITIAL VELOCITY. 410. The West Point ballistic machine. Fig. 132 represents the front and end views of an electro-ballistic machine originally devised by the author for the use of the Military Academy, and since adopted by the ordnance department, for proving powder, &c. C. Fig. 132. a is a bed-plate of metal, which supports a graduated arc (b). This arc is placed in a vertical position by means of thum.b-screw8 and spirit-levels attached to it; and it is graduated into degrees and fifths, commencing at the lowest point of the arc, and ending at 90~. -pp' are two pendulums having a common axis of motion, passing through the centre, and perpendicular to the plane of the arc. The bob of the pendulum p' is fixed, but that of p can be moved up and down with a thumb-screw, so as to make the times of vibration equal. m and m' are two electro-magnets attached to the horizontal limb of the arc, to. hold up the pendulums when they are deflected through angles of 90~. s and 8' are pieces of soft iron attached to the prolongations of the suspension-rods, in such way as to be THE WEST POINT BALLISTIC MACHINE. 391 in contact with the lower poles of the magnets, when the pendulums are deflected. d is an apparatus to record the point at which the pendulums pass each other, when they fall by the breaking of the currents which excite the magnets. It is attached to the prolongation of the suspension-rod pi; and consists essentially of a small pin enclosed in a brass tube; the end of the pin near the are has a sharp point, and the other is terminated with a head, the surface of which is oblique to the plane of the are. As the pendulums pass each other, a blunt steel point attached to the lower extremity of the suspension-rod p, strikes against the oblique surface of the head of the pin, which presses the point into a piece of paper clamped to the are, leaving a small puncture to mark the point of passage. An improvement to the foregoing consists' in attaching to the pendulum p' a delicate bent lever, which carries on its point- a small quantity of printer's ink; the pendulum p presses upon this lever-, causing the point to touch the are and leave a small dot opposite to the point where the pendulums pass each. other: The magnets are also so arranged that they can be transposed from one pendulum to the other, thereby affording the means of correcting errors arising firom inequalities of magnetic power, by taking a mean of two observations. c c and c' c' represent the wires which conduct the two electric currents to the magnets mr and m'.. Targets. The targets are two frames of wood placed so as to support the wires in a position to be cut by the projectile. For the purpose of obtaining the initial velocity, the first should be placed about 20 feet from the muzzle of the piece, that the flame may not break the 392 SCIENCE OF GUNNERY.-INITIAL VELOCITY. current before the projectile reaches it; the- position of the second depends on the velocity of the projectile. For cannon, it should be placed about 100 feet from the first target; and for small-arm and mortar projectiles, about 50 feet. The number of times that the wire should cross the targets depends on the size of the projectile and the accuracy of its flight. Carrents and batteries. The magnets should be made of the purest attainable wrought iron, in order that they shall retain no magnetic force after the exciting currents are broken; and for this purpose they are best made of bundles of wire. The batteries should be of nearly equal power and constancy, in order that, in case the magnets do retain a portion of their magnetism, the remaining portion may be as uniform as possible. Grove's or Bunsen's batteries are the best that can be used for this purpose. The power of the battery is regulated by the distance of the targets and the size of the conducting wires. If a weak battery be used, the magnetic power may be increased by increasing the diameter of the wire, or by resting pieces of soft iron.on the upper poles of the magnet. In experimenting with cannon, the machine should be placed about 120 yards from the piece, to prevent any disturbance from the discharge; at this distance the record will have been made before the sound reaches the machine. For this distance, three cups, in whiclkthe zinc cylinders are 8 inches long and 3 inches diameter, and an insulated copper wire.06" diameter, have been found to answer a good purpose. The disjunnctor. The disjunctor is a small auxiliary instrument for closing and breaking the currents at will. THE WEST POINT BALLISTIC MACHINE. 393 It affords the means of verifying the accuracy of the pendulum machine by a succession of simultaneous ruptures of the wires; when the machine is in good condition, the position of the point of meeting seldom varies a tenth of a degree, an error which corresponds to only.000154 of a second of time. When the currents are of equal strength, and the starting points are properly adjusted, the point of meeting will be found opposite to the zero of the graduated arc; if of unequal intensity, the point will be found near the zero point and on the side of the stronger magnet. As this position is nearly constant for the same currents, the error of the reading can be easily corrected. If the error be positive, subtract it; if negative, add it. Arrangement, &c. Figure 133 shows'the working arrangement of the several pieces: a represents the pendulum; b the disjunctor; c c and c' c' the currents; e e' the batteries; and d the position of the gun. To operate them, the disjunctor is closed, the pendulums are deflected, the markingpin revolved perpendicular to the are, the piece is fired, and the position of Fig. 133. the puncture in the paper, with reference to the graduated are, noted. To determine the time. The velocity of the electric currents being considered instantaneous, and the loss of power of the magnets simultaneous with the rupture of the currents, it follows that each pendulum begins to move at the instant that the projectile cuts the wire, and that the interval of time corresponds to the differ. 394 SCIENCE OF GUNNERY.-INITIAL VELOCITY. ence of the arcs described by the pendulums up to the time of meeting. Let m and m', fig. 134, represent the positions of the two magnets, and let the interval between the rupture be such that the centres of oscillation will pass each other at i. As the times of vibration are equal, the interval of time will correspond to the are i i', the arc m' i being equal Fig. 134. to mn i'. A vertical line through the centre of motion bisects the are i i'. The reading therefore corresponds to one-half of the required time, or time of passage of the projectile between the wires. To determine a formula for the time that it takes for one of the pendulums to pass over a given are, let I be the length of the equivalent simple pendulumn, v the velocity of the centre of oscillation or point n', y the vertical distance passed over by this point, x the variable angle which the line of suspension'makes with the horizontal, and t' the time necessary for the point m' to pass over an entire circumference, the radius of which is 1, with a uniform velocity v, we have, V = A2gy. Substituting for y its value in terms of the constant angle of half-oscillation and the variable angle x, the above expression becomes, V- 2gl cos. (90~-x); from which we see that the velocity of the pendulum increases from its highest to its lowest point, and vice vqerSa. The time t' is equal to the circumference of the circle, the radius of which is i, divided by the velocity, v; THE WEST POINT BALLISTIC MACHINE. 39.5 again divide this by 360, we have the time of passing over each degree, or, 2l360/2o1 eo.(90o- )~ To determine 1, it is necessary to change the cylindrical arms of suspension to knife-edges, in order to determine the time of vibration through a very small arc. The mean of 500 vibrations will be very near the exact time of a single. vibration. Knowing the time of a single vibration, the length of the equivalent simple pendulum can be obtained by the relation l='t"2, in which t" is this time, and 1' is the length of the simple second's pendulum at the place of observation. At West Point 1'= 39.11448 inches. "4 "- g=32.17050 feet. In this way all the constants of the expression for t are known, and by assigning different values to x, a table can be formed, from which the times corresponding to different arcs can be obtained by simple inspection. The table in chapter XIII. is calculated for the West Point machine. MOTION OF A PROJECTILE IN VACUO. 411. Determination of equations of motion. Aprojectile is a body thrown or impelled forward, generally in the air; and the trajectory is the line described by its centre of inertia. The movement of a projectile will be considered firstly in vacuo, and secondly in the air. Let A (fig. 135) be the position of the muzzle of a fire-arm, and the line A B its axis prolonged. 396 SCIENCE OF GUNNERY.-MOTION IN VACUO. Fig. 135. Let 0 represent the angle which this line makes with the horizontal plane, or the angle of projection. V the initial velocity. 2v the velocity at the point m. t the time of flight to the same point. o the inclination of the tangent at this point. x, y, the co-ordinates of this point. X the horizontal range. Y the greatest height of ascent. Tthe whole time of flight, or for the range X. If the projectile were only acted upon by the force of the discharge, it would move in the straight line A B, and after a time, t, would reach the point P; but it is constantly drawn to the earth by the force of gravity, and instead of being found at the point P, it is found at the point rn, situated at a distance below P equal to the distance which it would fall in the same time under the influence of gravity, or ~gt2, g being the velocity generated by gravity in a second of time. The distance PC is equal to x tan: 0; the distance wC, or y, is equal to this distance diminished to,gt2, or, y=_x tan. -- ~gt2; X=t V cos. p, or t. Substituting this for t in the preceding equation, it becomes, g x2 y-x tan. -- - V2 -$. 2 ~cs MOTION IN VACUO. 397 From the laws which govern falling bodies, V — /2g,; or V2=2gH; in which H is the height due to the velocity V. Substituting this value of V2, the equation becomes, 2 y=x tan. H —4 (1) which is the equation of a parabola. From the same figure we obtainy — Vt sin. -- ~-gt2. (2) -= Vt cos. ~. (3) (i) - j cos. (4) 2d. To determine the vertical ascent and horizontal range of the projectile, differentiate equation (1), and place the value of O; whence we obtain, ax X- 4 Hsin.0 cos.O= 2Hsin. 20. (5) }X being the abscissa of the highest point, Y- Hsin.20. (6) The first value of X shows, that the range can be obtatined with two angles of projection, p2rovided they be complements of each other; the second value shows, that the greatest range corresponds to an angle of 45~, and that this range is equal to twice the height due to the yelocity; and, also, that:variations in the angle of fire produce less variations in range as the angle of fire approaches 45~. 3d. If two projectiles be thrown under the same angle, with different initial velocities, V and V', the ranges being X and X', we have, V2 V'2 X- 2 Hsin. 2= -— sin. 2, and X' sin. 2; g g 398 SCIENCE OF GUNNERY.-MOTION IN VACUO. and from these we have, V 4 (7) * V VX Therefore, under the same angle of fire, the ranges are proportional to the squares of the velocities; and rec'iprocally, the velocities are proportional to the square roots of the ranges. 4th. The velocity at any point is equal to t, or 2= dy2+dx2 24= +dat2 Substituting the values of dy and dx, obtained by differentiating equations (2) and (3), we have v2= V2 2 Vgt sin. +g2t2. Substitute for -2 Vgtsin.~+g2t2 its value- 2gy, derived from equation (2), we have, v2 V- 2gy. Replace V2 by 2gHl and reducing, the expression becomes, v=~/2g(H- y). (8) This shows that the velocity of a projectile, at any point, depend8 on it8 height above the muzzle of the piece; and that it is equal to that which is attained in falling through the height (H- y). It also shows that the velocity is least when y is greatest, or at the summit of the trajectory; and that the velocities at the two points in which the trajectory cuts the horizontal plane are equal. 5th. The total time of flight may be determined by substituting the value of X 4Hsin.~cos.~, equation (5), in equation (4), which becomes 4Hsin.+ Vsin.~ (9) V - MOTION IN VACUO.'399 If = 45~, sin.o-4/'I, and V=4gXJ Calling ] the time of flight, we have, A,= A/ S 16. 7 4 Hence the time of flight for an angle of 450 is equal to the square root of the quotient of the range divided by one-hcalf of the force of gravity; or, it is8 approximately equal to one fourth of the square root of the range expressed in feet. 6th. The tangent of the angle made by a tangent line at any point of the trajectory is equal to d, which dx is obtained by differentiating equation (1); calling this angle o, we have, tan.o —tan.* —2os. 2&~ (10) Substitute the value of X= 4 H sin.~ cos.~, the angle of fall on horizontal ground is tan.0= -tan.+; that is to say, the angle of fall is equal to the angle of projection, measured in an op posite direction. 7th. The position of a point being given, to find the initial velocity necessary to attain it, let a and b be the horizontal and vertical co-ordinates of this point of the curve, and E its angle of elevation. Substituting these quantities in equation (1), and recollecting that tan. e=-, we have, a cos.e 4 sin. ( —E). coS.0s or, V-k ag cos.e (11) 2 sin.( -)'cos.0 400 SCIENCE OF GUNNERY. —INITIAL VELOCITY. 8th. The position of a point being given, to find the angle of fire necessary to attain it. Substituting a and 6 for x and y in equation (1), we have, a2 b6=a tan.+- H -,a 4 cos.2. from which to determine ~. Making tan.=- a, we have, cos. 2 = which be ing substituted in the above equation givesa=tan.i=a(2Hiv/If1_i 2-L- 4 a) (12) The two values of tan.+ show that the point may 6e attained b6y two alngle8 of projection; and the radical shows the solution of the problem i, possible when the quantity under it is positive; or, 4]J2 >4H6 b+a2. 412. Practical application of formula. The preceding formula will only be found to answer in practice for projectiles which experience slight resistance from the air, or for heavy projectiles moving with low velocities, as is commonly the case with those of mortars and howitzers. The following table gives the difference between the observed and calculated times of flight of the French 8 and 10-inch mortar shells, weighing 64 and 119 lbs. respectively. The initial velocities being unknown, the times are calculated from the observed ranges. The observed times are invariably greater than the calculated times, as might be expected from the resistance of the air, which retards the motion of projectiles. PRACTICAL APPLICATION OF FORMULA. 401 - ~;: Ranges at angles of Times of flight..Q_~ it 450 30~ A: 45~ 30~ Calcu- CalcuObserved. lated. Observed. lated. Kilog. Meters. Meters. Seconds. Seconds. Seconds. Seconds. 0.234' 343 290 9.8 8.4 6.8 5.8 8-inch. 0.351 629 561 12.9 11.3 10.0' 8.1 0.585 1146 1011 16.0 15.3 12.3 10.9 0.994 1792 1690 20.8 19.2 16.9 14.1 0.468 457 383 11.0 9.7 7.5 6.8 0.693 734 637 14.0 12.2 10.0 8.7 10-inch. 1.054 1132 980 17.0 15.2 1 12.0 10.2 1.405 1555 1355 20.0 17.8 14.0 12.6 1.639 1757 1516 23.0 18.9 15.0 13.4 The next table shows the observed and calculated ranges, for 30~ elevation, and the observed ranges for 450 elevation, for the above projectiles, the initial veloc. ities being the same for each projectile. Ranges of 10-inch Mortar Shells. Ranges of 8-inch Mortar Shells. 450 300 450 300 elevation. elevation. elevation. elevation. Calcu- CalcuObserved. Observed. lated. Difference Observed. Observed. lated. Difference Meters. Meters. Meters. Meters. Meters. Meters. Meters. Meters. 457 383 396 +13 343 290 298 + 8 734 637 637 0 629 561 545 — 16 1132 980 982 + 2 1146 1011 993 - 13 1555 13,55 11350 - 5 1792 1690 1552 — 138 1757 1516 1522 + 6 It appears from the foregoing tables, that the ranges of mortars with different degrees of elevation, can be calculated up to about 1,400 yards from equation (5), or, X= 2H sin. 20, 26 402 SCIENCE OF GUNNERY.-RESISTANCE OF THE AIR. and the times from equation (4), or X Vcos. + RESISTANCE OF THE AIR. 413. Importance of considering it. A body moving in the air experiences a resistance which diminishes the velocity with which it is animated. That the retarding effect of the air, on projectiles moving with high velocities, is very great, is seen by comparing the actual ranges of projectiles with those computed under the supposition that they move in vacuo. Thus, it has been shown that certain cannon-balls do not range one-eighth as far in the air as they would if they did not meet with this resistance to their motion; and small-arm projectiles, which have but little mass, are still more affected by it. 414. Law of resistance. IncompreS8ible fuiid. The resistance experienced by a plane surface moving parallel to itself through an incompressible fluid, is equal to the pressure of a column of the fluid, the base of which is the moving surface, and its height that due to the velocity with which the surface is moved through the fluid, or, firom the law of falling bodies, h=- 2 in which h is the height, v the velocity, and y the force of gravity. The resistance on a given area is therefore proportional to the square of the velocity, and the density of the fluid medium. Let d, X, and v represent the density or weight of a LAWS OF RESISTANCE. 403 unit of volume of the fluid, the area pressed upon, and the velocity of the moving surface, respectively, and P the resistance in terms of the unit of weight, and we have, p=-kd; (13) in which k is a coefficient to be determined by experiment. ComHpressi6le luid. If the medium be formed of compressible gases, as the atmosphere, the density in front of the moving body will be greater than that behind it; and it will be readily seen that the body will meet with a resistance which increases more rapidly than the square of the velocity, in such a manner that the coefficient k, or the density of the medium, l, should be increased by a quantity which is a function of the velocity itself, or, what is the same thing, by adding another term to the resistance which shall be proportional to the cube of the velocity. In examining the table of resistances, obtained by Hutton from firing a one-pound ball into a ballistic pendulum, at different distances, and with velocities varying from 300 to 1,900 feet, Piobert found, that if t in the foregoing expression be replaced by the binomial u2 term, ), in which - 142-7 ft' the expression would nearly satisfy the results of experiments. Calling A-,kd and irR2 the area of the cross section 2gq of a projectile, the general expression for the resistance in air becomes, p — Ar2(l 1 2. (14) p~drb~- r -u 404 SCIENCE OF GUNNERY.-RESISTANCE OF TIHE AIR. In thiS expression, A is the resitance, in pounds, on a &quare foot of the cross-section of a projectile moving with a velocity of one foot; r is a linear quantity depending on the velocity of theprojectile. For all service spherical projectiles, A-.000514; and for all service velocities r-1,427 feet. The value of A for the riflemusket bullet (page 312) has been determined at the Washington Arsenal, by the method laid down, in the note on page 411, and found equal to 0.000358. This shows that the resistance of the air is about one-third less on the ogeeval than on'the,pherical form of projectile. This value has been found to answer well for calculating the ranges of rifle-cannon projectiles. The coefficient A, being a function of the density of the air, its value depends on the temperature, pressure, and hygrometric condition; in the above value the weight of a cubic foot of air-=.0T5 lb., at.a temperature of 600 Fahr., and for a barometrical pressure of 29.5 inches. If the surface of the projectile be rough or irregular, the value of this coefficient will be slightly too small. Example.-What is the pressure of the air on a 42-pdr. shot moving with a velocity of 1,500 feet? 1500 =-.000514 x 3.141x.292 x 150021+ 1427] =629.3 lbs. 415. Fall of a projectile ill the. air. The motion of a body falling through the air, will be accelerated by its weight, and retarded by the buoyant effort of the air, and the resistance which the air offers to motion. As the resistance of the air increases more rapidly than the velocity, it follows that there is a point where the retarding and accelerating forces will be equal, and that beyond this, the body will move with a uniform veloc. FALL OF A PROJECTILE IN THE AIR.:405 ity, equal to that which it had acquired down to this point. The buoyant effort of the air is equal to the weight of the volume displaced, or PD; in which P is the weight and D the density of the projectile, and cd the density of the air. When the projectile meets with a resistance equal to its weight, we shall have, P(1-jI >A7rRB2v2( +9; (15) in which the weight of the displaced air is transferred to the first member of the equation. As the density of the air is very slight compared to that of lead or iron, the materials of which projectiles are made, - may be neglected. Making this change, and substituting for P, 3-j7rI3D) (j having been divided out of the second member, should be omitted in the first), the expression for the final velocity reduces to 9 3 A' The resistance on the entire projectile for a velocity P of 1 foot, is ArrR2; dividing this by -, or the mass, we get the resistance on a unit of mass. Calling this 2-, we have, 1 ArR2 P 2 p, or 2gc- A R2'. 406( SCIENCE OF GUNNERY.-LOSS OF VELOCITY. Substituting for P its value in the equation of vertical descent; we have, 2g 2(l-+,); from which we see that v depends only on c; but 2 RD 3 gA hence, the final velocity of a projectilefalling in the air is directly proportioned to the product of its diameter and density, and inversely proportional to the density of the air, which is a.factor of A. The. expression for the value of (c) shows, that the reta'rding effect of thie air is less on the larger and denser projectiles. To adapt it to an oblong projectile of the pointed form, the value of 1)D should be increased, (inasmuch as its weight is increased in proportion to its cross section,) while that of A should be diminished. It follows, therefore, that for the same calibre, an oblong projectile will be less retarded by the air than one of spherical form, and consequently with an equal and perhaps less initial velocity its range wqill be grEeater. The value of (c) for service projectiles will be found ready calculated in the tables of fire, in'Chap. XIII. LOSS OF VELOCITY BY RESISTANCE OF THE AIR. 416. Equations of motion. For the purpose of determining the velocity which a projectile loses by the resistance of the air, in moving through a certain distance, x, the force of gravity may be disregarded; in which case the trajectory described will be a right line. LOSS OF VELOCITY BY THE AIR. 407 Let V be the initial velocity, and v the remaining velocity at the end of the distance x. The expression for the resistance of the air is, as we have seen, =A7R2l +~)V2. But we know that the retarding force of the air is equal to the mass of the projectile against which it acts, multiplied by the first differential coefficient of the velocity, regarded as a function of the time, with its sign changed, I) and that _ is the mass of the projectile. We have, therefore, P -dt P 4 4 RD Recollecting that P= —7rR3 D, and that 2c= - -, the 3 3gA equation reduces to, dvt 2 /1 dt- 2cj J) Integrating this equation between the limits 0 and x, which correspond to V and v, we have, t==2c( - 1~ ) log. _ (18) To obtain a relation between the space and velocity. dx dx we have v= —, or dt=; substituting this in the equadtv Q tion for the intensity of the retarding force, and reducing, we have, dx= cdv 408 SCIENCE OF GUNNERY. —LOSS OF VELOCITY. Integrating between the same limits as in the preceding case, we have, r X x=2c log. -or 1 + I 1+- Solving this equation with reference to v, we have, (l+::1101 (20) Substituting, in equation (18), x for its value given in equation (19), we have, t=2c (l2i-) (21) The logarithms in the above equations belong to the Napierian system, and are obtained by multiplying the corresponding common logarithm by 2.3026:e —2.713. Practical remarks. Equation (19) gives the space passed over by a certain projectile when the velocities at the commencement and end of the flight, are known. Equation (20) gives the remaining velocity when the initial velocity and the space passed over are known. Equation (21) gives the time of flight when the velocities at the beginning and end and the space passed over, are known. The distance at which the velocity Vis reduced to v, and the duration of the trajectory, being proportional to c, are directly proportional to the product of the diameter and density of the projectile, and inversely proportional to the density of the air. This fact shows the great advantage, in point of range, to be derived from THEORY. 409 Mussing large projectiles over small ones, of solid projectiles over hollow ones, of leaden projectiles over iron ones, and of oblong projectiles over round ones. FORM OF PROJECTILE. 417. Theory. When a body moves through the air, the gaseous particles in front are crowded upon each other until they meet with a certain resistance, after which they move off laterally, and finally pass around and arrange themselves in rear of the moving body. It is evident that the difference of the densities, or pressures, front and rear, depends on the velocity with which the displaced particles rearrange themselves after displacement; and this, in turn, depends on the shape, and extent of the surfaces of the moving body. The best form for -a projectile can only be determined by ex. periment, as theory and experiment do not agree in their results. According to theory, if a plane of given area be moved through the air, it meets with a resistance which is proportional to the square of the sine of the angle which its direction makes with that of motion. The experiments of Hutton with low velocities show that this is only true in cases of 0~ and 900; that from 90~ up to 500 or 60~, the resistance is nearly proportional to the sine; beyond this, it decreases a little more rapidly than the sine, but not so rapidly as the square of the sine: 410 SCIENCE OF GUNNERY. —LOSS OF VELOCITY. For an angle of 220 it is only - the resistance proportional to the sine. 9 2 4 it 40 64 1 C i 5 "e " 2 44 1,,,, it 6 418. Experiments of Hutton and Borda. The following are the results of the experiments made by Hutton and Borda, on the resistances experienced by different forms of solids moving through the air with velocities varying from 3 to 25 feet per second. HUTTON'S EXPERIMENTS. VELOCITY, 10 FEET. Kind of surface, Experimental Theoretical resistance. resistance. No. 1 Hemisphere (convex surface in front), 119 144 No. 2 Sphere, 124 144 No. 3 Cone, elements inclined to the axis 250 42', 126 53 No. 4 Disk, 285 288 No. 5 Hemisphere (plane surface in front), 288 288 No. 6 Cone (base in front), 291 288 Fig. 136. BORDA. Kind of surface. Experimental Theoretical No: 1, Prism, with triangular base, 100 100 No. 2, " " 52 25 No. 3, " semi-ellipse, 43 50 No. 4, " ogee, 39 41 Fig. 13'7. _________________I_ CONCLUSIONS. 411l 419. Conclusions. The foregoing experiments show: 1st. That the results of theory do not agree with those of practice. 2d. That rounded and pointed solids suffer less resistance from the air than those which present flat surfaces of the same transverse area, but, at the same time, the sharpest points do not always meet with the least resistance. 3d. That where the front surfaces were the same, the resistance was least with those in which the posterior surfaces were the flattest. 4th. That the ogeeval form, or the form of the present riflemusket bullet, experiences less resistance than any other tried. These experiments, as before remarked, were made with low velocities, compared to those which ordinarily actuate projectiles, and the conclusions which have been drawn from them may not be strictly applicable in practice. Now that oblong projectiles are used in all kinds of fire-arms, it is important to determine that form which will be least affected by the resistance of the air. It is evident that that form will be the best which, on trial, is found to give the least value to A in equation (1 4), or, what is the same thing, to give the greatest value to c in equation (21).* * The author proposes the following method of determining the value of c by the electro-ballistic machine. Establish four targets in the line of fire, in such manner that the first shall be near the piece, the second shall be at a distance x from the first, the third at a distance 2x from the first, and the fourth at a distance of 4x from the first; let t, t', and t" represent the intervals of time corresponding to the distances between the targets. respectively; let v be the velocity at the middle point between the first and third targets, or at the distance x, and let v' be the velocity at the middle point between the first and fourth targets, or at the distance 2x. Equation (21) becomes 2e 2c x 2c 2c x v V r V v rt. V 1' V v r 412 SCIENCE OF GUNNERY.-TRAJECTORY IN AIR. TRAJECTORY IN AIR. 420. Difficulties of the problem. In consequence of the variable nature of the resistance of the air, it has been found impossible to integrate the differential equations of the real trajectory, even under the supposition that this resistance varies in as simple a ratio as the square of the velocity. Several distinguished mathematicians have obtained expressions which approximate to the true results, but the expressions are generally too complicated to be of much practical value. 421. Didion's method. Captain Didion, professor of gunnery in the artillery school at Metz, however, furnishes an approximate solution to this difficult question, which may be used in practice. To do this, he considers the resistance of the air equal to A~rR2( @1~)v2; and by assuming a mean value for the different inclinations of the elements of the trajectory to their horizontal projections, which makes d$ constant, he is able to 2c. Since V is the same for all the distances, we have t —-t'2c x 2c 2x r vq.-t, I or c-. V v J 2x 4x From the note on page 389, we are at liberty to place v —- and v'-=-t7; substituting these values in the preceding equation, reducing and changing the signs of both numerator and denominator of the second member, we have 2x( -t+) t" —2t' Which equation gives the value of c in terms of t, t', t", and which can be determined by taking the mean of several shots, with the electro-ballistic machine, at the different distances, x, 2x, and 4x. DIDION'S METHOD. 413 integrate the differential equations, and place them under the following forms: X2 y=x tan. -- V 2 B; 2 V cos.2 x Tan. 0= tan. — g V2s bI t Vcos. 4 1 cos.' -cos. 0 U The same notation being preserved as in the equations in vacuo (page 397), it will be perceived that the equations in air differ from those in vacuo, by the multipliers,B, ]P D, and U; respectively. The multiplier B relates to the fall of the projectile; I, to the inclination; D, to the duration; and U to the velocity; they are each functions of a and; ink C r which a is the constant relation of the are to its projection, V,- V cos. ~, and c and r are co-efficients of the formula for the resistance of the air. (See pages 403 and 40.6.) The general expression for a particular multiplier, B for instance, is B(, -;'). The values B 1, ]D, and U, for such values of c and r as are likely to arise in service, have been computed, and arranged in tabular form; these tables, their construction, and use, are explained in chapter XIII. So long as the inclination of the trajectory is slight, a differs but slightly from unity; for an angle of 15~ it does not exceed 0.01; and as it only enters into the term which relates to the resistance of the air, the error 414 SCIENCE OF GUNNERY.-TRAJECTORY IN AIR. does not exceed a pressure corresponding to 0.25 in. in the height of the barometer; it may, therefore, be reX garded as unity, and a reduces to. The same with a.V, a Vcos.0 regard to', or; as a cos. p, when - 10~, r r differs only about 0.01 from unity; and this expression V may be reduced to -. When the angle of projection does not exceed 3~, cos. 0 differs only.001 from unity, and we can everywhere replace V cos. p by V. Under this angle, differs but slightly from unity, and we cos. 0 have v-= which is the same as if motion took place in a horizontal plane. All cases of the movement of projectiles which occur in practice, may be divided into three distinct classes: 1st, When the angle of projection is slight, or does not exceed 3~, as in the ordinary fire of guns, howitzers, and small-arms; 2d, When the angle of projection is greater than this, but does not exceed 100 or 15~, as in ricochet fire, &c.; 3d, When the angle of projection exceeds 155, as in the fire of mortars. 422. 1st Class. For small angles of projection, as in guns, howitzers, and small-arms. For slight variations of the angle of projection above or below the horizon, the form of the trajectory may be considered constant;* and when the object is but slightly raised above, or depressed below the horizontal plane, it may be considered as in this plane. In consequence of the windage, and the balloting of FIRST CLASS. 415 the projectile which results from it, the projectile does not always leave the bore in the direction of the axis. The angle formed by the line of departure and the axis of the piece, is called the angle of departure. For guns'in good condition, the vertical deviations do not exceed 5', and for howitzers 10'; the side deviations never exceed 4' 30". To obtain exact results, therefore, it is necessary to correct the angle of projection for the angle of departure, when the latter is known. cos_. Under the supposition that a, cos. 0, and cos. O are each equal to unity, the equations of the trajectory in air may be reduced to2 y=x tan. 0-9XB; (22) Tan. o= tan. -- g-2Ii (23) (24) U= (25) U' Knowing the weight and diameter of the projectile, e can be calculated by the formula c_- if it be 3gA not found in the table which accompanies it. We X V know - and V, and by means of the tables can deterC r mine the desired values of B, 1; D, and U. Of the three things, thd initial velocity, J7 the distance of the object, X, and the angle of projection, 0, two being known, to determine the third. 1st. To determine the angle of projection, ~.-Make y=O in equation (22), and solve it with reference to 416 SCIENCE OF GUNNERY.-TRAJECTORY IN AIR. tan. 0, we have, tan. _ VX -2B. 2 V2 Examnple. —Find the angle of projection necessary to throw a 12-pdr. shot 1800 feet, with an initial velocity of 1500 feet. We 1800 V 1500 have V=1500 feet; - 137800=0.5336; 142- =1.054. From C 3370 r 1427 32.17 1800 Table (1), B=1.449; tan. = 2. 1500.449. - 0.01864. 10 05'. 2d. To determine the initial velocity, V, make y O, in equation (22), solve it with reference to V, and multiply both members by -, we have. V i vr the value of the value of V, which gives that of q; multiply - by 1427 and we shall have V. Example. —Find the initial velocity of a 12-pounder shot which, fired under an angle of 10 05', has a range of 1800 feet. 1 16.08 x 1800 1427 0.01864 V -1.05. V=1.05 x 1427-1498.35 feet. 3d. To determine the ranyg, X.-Make y=O in equation (22), obtain the value of X, and divide both mein. bers of the equation by c, we have, ~XB= tan. V2 c c-g FIRST CLASS. 417 Having the initial velocity, V; and angle of projection, ~, we can determine, Vandp; seek in table (4), V _ISX for the value of, that of X which givesp; having X, multiply it by c, and we have X. Example.-Find the range of a 12-pdr. ball, fired under an angle of 1~ 05', with an initial velocity of 1500 feet. V c=3370; _=1.0511; tan. = —0.01864. 0.01864 1500 X 0 -01864 -=500 0.774; (from table 4), X-.5340;X=.5340 38370 16.08 c x 3370 1800 feet. The slight discrepancies in the three preceding results, arise from the neglected decimals. In; firing spherical case-shot, it is important not only to know the time of flight, in order to regulate the fuze, but it is important to know that the projectile will have sufficient remaining velocity to render the impact of the contained projectiles effective. 4th. The time of flig/ht can be obtained from equation (24), or, t —VD. Knowing - and, e can ob tain the corresponding value of D from table (3). Example.-Find the time of flight of a 12-pdr. spherical case-shot for a distance of 1500 yards, the initial velocity being 1500 feet. X_ 4500 V 1500 X -- 450 1.335; __ _1.051; D= 1.859. c 3370 r 1427 t=451.859 —5.58 seconds. 1500 5th. IThe remaining velocity can be obtained from 27 418 SCIENCE OF GUNNERY.-TRAJECTORY IN AIR. V noXn V equation (25), or, v= Knowing -and, obtain from table (3) the corresponding value of U. Example-Find the remaining velocity of a 12-pdr. spherical caseshot at the distance of 1500 yards, the initial velocity being 1500 feet. X 4500 V 1500 -1.327; = 1.051; U.2.882; v — -520 feet. c 3370 r 2.882 This velocity is more than sufficient for a musket-bullet to disable an animate object at the distance of 1500 yds. 423. 2d class. For aungle8 of projection not exceeding 100 or 150, a& in the ricochet fire of guns, howitzers, and rnortars. The formulas are: y=x tan. P-j 2sB. (26) tan.0= tan.- - g V2cos.2 (27) t= -i D. (28) V cos.D Ucos.0 Fov s (29) If the object be on a level with the piece, the solution of this class of problems is the same as those of class 1st, when the angle is very small; if not, it will be necessary to substitute for 7 V, = cos. q, and after having obtained V,, divide it by the cos. 0, which gives TVI The object being situated at the distance a from the piece, and at the distance b above the horizontal plane passing through the centre of the muzzle, is seen under an angle of elevation e, for which tan.e-=. One of the a SECOND CLASS. 419 two things, the initial velocity or angle of projection being known, to determine the other. 1st. To determine the initial velocity, V; Substitute in equation (26) the co-ordinates a and b, and V; solve it with reference to V,; substitute tan. e for -, and divide both members by r, we have, r 1 2 /B r / tan. -tan. - Having the value of q, seek in table (5) for the known value of the va of corresponding to it, and multiplying by, we shall have V. Example.-Find the initial velocity of an 8-inch siege-howitzer shell, whicli, being fired under an angle of 120, will strike an object situated 1,000 feet from, and 20 feet above, the muzzle of the piece. 20 Tan.b=0.2125; tan.e-=100=0.0200; tan.+ —tan.e-=0.1925; 1000 a 1000 1 16.08.1000 cos.-=0.97s1; --- 8=0.2801; q=1427 - C 35'70 1427 2/ 0.1925' WV 0.2150. 1427 0.2023; -=0.2150; V - =313 feet. r 0.9781 2d. To determine the angle of projection. The result will be sufficiently near the truth, if we substitute, in equation (26), Vfor V, or Vcos. p; and solving it with reference to tan. ~, we have, tan.+=tan. E+ ga B, 2V2 in which we substitute for B its value, corresponding to a and obtained from table (1). C r 42-0 SCIENCE OF GUNNERY.-TRAJECTORY IN AIR. Examnple.-What angle of projection is necessary for an 8-inch siege-howitzer shell to strike an object situated 1000 feet from, and 20 feet above, the muzzle? The initial velocity being 313 feet, ca 1000 V 313 20 V=313 feet;= 3570- 0.2801; =1427 =0.2193; tan.e=1000 16.08.1000 =0.0200; tan. 0=0.0200+ -' 1,1.42=0.2084; p=11o 28'. 313 424. 3d class. Properties of trajectories under high angles of projection. As a projectile rises in the ascending branch of its trajectory, its velocity is diminished by the retarding effect of the air and the force of gravity: in consequence of the resistance of the air alone, the velocity continues to diminish to a point a little beyond the summit of the trajectory, where' it is a minimum; and from this point it increases, as it descends, under the influence of the- force of gravity, until it becomes uniform, which event depends on the diameter and weight, of the projectile and the density of the air, or, in other words, upon the value of c. The inclination of the trajectory decreases from the originato the summit, where it is nothing; it increases ih the descending branch from the summit to its termination, and if the ground did not interpose an obstacle, it would become vertical at an infinite distance. An element of the trajectory in the descending branch has a greater inclination than the corresponding element of the ascending branch. Strictly speaking, the trajectory in air is an expotential curve with two asymptotes; the first is the axis of the piece, which is tangent to the trajectory when the initial velocity is infinite; the second is the vertical line toward which the trajectory approaches as the horizon THIRD, CLASS. 42_1 tal component of the velocity diminishes, and the effect of the force of gravity increases. The curvature of the trajectory increases in the ascending branch, to a point a little beyond the summit. The point of greatest curvature is situated nearer the summit than the point of minimum velocity. In the fire of mortar shells under great angles of projection, and at customary distances, the trajectory may be considered as an arc, in which the angle of fall is slightly greater than the angle of projection. In the ascending branch, the arc commences under an angle of W, and terminates under an angle of 0; the ratio of the length of this arc to its projection, or a, is calculated for all arcs from 50 to 750, and arranged, in groups of fives in the accompanying table. The value of a is considered the same in the descending as in the ascending branch. ARCS. a ARCS. a ARCS. a ARCS. 50 1.00127 300 1.05306 550 1.27583 10 1.00516 35 1.07596 60 1.38017 15 1.01184 40 1.10730 65 1.53433 20 1.02165 45 1.14777 70 1.77772 25 1.03514 50 1.20189 75 2.20349 The multipliers, B, i, D, and the divisor, U. are calculated for the values ax and a and they are employed in equations (26), (27), (28), (29), as in the preceding class of cases. 1st. Find the initial velocity of a nortar shell, knowing the range and angle of projection. We know, and by solving equation (26) as before, 422 SCIENCE OF GUNNERY.-TRAJECTORY IN AIR. we have, aV a - LgX r r- tan.0 4/B Having determined the value of q, seek in table a V aX (5) the value of'corresponding to it for -; then r multiply it by a, and we have -V. a CoS.S Example.-What initial velocity is necessary to project a 10-inch shell 1,800 feet, under an angle of 45~ 2 ax For a 10-inch shell, c — 4677; for 45~, a = 1.148; 1.148.1800 1.148 16.08. 1800 4677 - 0.4418; 0- 1427 1 0.1369. By the aV aid of table (5) we find' —0.1490; and from this we get 0.1490. 1427 V — — 262 feet. 1.148. 0.7071 2d. To determine the angle and qvelocity of fall, and the timte of fiight, knowing the initial velocity and range. Let the projectile be the same as in the preceding case. aX aV Example.-We have -0.4418; and'-0.1490; from taC r ble (1) we have I 1.291; from table (2), D 1.127; and U= 1.272. Substituting the proper values in equation (25) we have Tan. 0-1.00000- 32.17. 187070 1.280 -1.159; 0- -49~ 12'. (262.0.707 1)2 - The negative sign indicates that the angle of fall is measured in an opposite direction from the angle of projection. Making the proper substitutions in equations (28) and (29), we have 1800 262.0.'7071 - 18 1.127- 10.95". v 222 feet. 262. 0.071 1 272. 0 6534 3d. To determine the range, knowing the initial ve. locity and angle of projection. TRAJECTORY OF OBLONG PROJECTILE. 423 We have a, and a, make y=o in equation (26); solve it with reference to X, and multiply both members by a and we have, aX aV2. BX- a-sin. 20=p. c ge ofaX aV/ Having found the value of which for a / gives p (table 4); multiply it by', and we have X. Example.-Find the range of a 10-inch mortar shell, the angle of projection of which is 45~, and the initial velocity is 262 feet. aV Cos. 0b=0.7071; the sin. 2-=1.0000; and a=1.148; - r 1.148.262.0.7071 aV9. 1.148. 262 - 0.1490; p - sin.2 3217 467 1.0000 -1427 g 32.17.4677 aX o.4412.J677 0.5238 from table (4) 0.4412; X= 1' 1798 feet. c 1.148 The slight discrepancies in these, as in the preceding results, arise from the neglected decimals. 425. Comparison of true and calculated trajectories. In consequence of considering the inclination of the trajectory as constant in the preceding equations, the resistance of the air is slightly underestimated in the more inclined portions of the trajectory, or at the beginning and end, and slightly overestimated in the less inclined portions, or about the summit. It follows that the calculated trajectory will at first rise above the true one, then pass below it, and again pass above it; the calculated ranges will therefore be found slightly in excess. 426. Trajectory of oblong projectile. From the law 424 SCIENCE OF GUNNERY.-DEVIATION OF PROJECTILES. of inertia, a rifle projectile moves through the air with its axis of rotation parallel to the axis of the bore. Hence, it follows, that an oblong projectile, fired under a low angle of projection, presents a greater surface toward the earth, and less parallel to it, than a round projectile of the same weight; consequently the vertical component of the resistance of the air is greater, and the horizontal component less, in the first case than in the second. The effect of this will be to give an oblong projectile a flatter trajectory and longer range than a round one. DEVIATION OF PROJECTILES. 427. Nature atd causes. The path described by the centre of inertia of a projectile, moving under the influence of gravity and the tangential resistance of the air, is called the normal trajectory; and it is this trajectory which has been the subject of the preceding discussions. In practice, various causes are constantly at work to deflect a projectile from its normal path, and it becomes necessary to study the nature of these causes, and their effects. All deviating causes may be divided into two classes -those which act while the projectile is in the bore of the piece, and those which act after the projectile has left it. The first class includes all the causes which affect the initial velocity, and give rotation to the projectile; the second includes the action of the air. 428. Causes which affect initial velocity. The principal causes which affect initial velocity are variations in the weights of the powder and projectile, the manner ROTATION. 425 of loading, the temperature of the piece, and the balloting of the projectile along the bore. Experiments made by firing siege and field projectiles into the ballistic pendulum, show that, with care, the mean variation in the initial velocity, in a series of fires, does not exceed 20 feet. A variation of 20 feet in initial velocity only produces a variation of - a foot, in the vertical height of the trajectory of a 12-pdr. ball, at a distance of 1,000 yards. 429. Rotation. The principal cause of the deviation of a projectile is its rotation combined with the resistance of the air. It is proposed, in the first place, to show how rotation may be produced, and, in the second, to show how rotation, combined with the resistance of the air, produces deviation. By balloting. If the projectile be spherical and homogeneous, rotation is produced by the bounding or balloting of the ball in the bore, arising from the windage. In this case the axis of rotation is horizontal, and passes through the centre of the ball; the direction of rotation depends on the side of the projectile which strikes the surface of the bore last; if it strike on the -upper side, the front surface of the projectile will move upward; if on the lower side, this surface will move downward. The velocity of rotation from this cause depends on the windage, or depth of the indentations in the bore, the charge being the same. It has been found to be, for ordinary windage, about 30 feet for a 24-pdr. shell fired with 2+ lbs of powder. By eccentricity. If, from the structure of the ball, or from some defect of manufacture, the centre of gravity do not coincide with the centre of figure, rotation 426 SCIENCE OF GUNNERY.-DEVIATION OF PROJECTILES. generally takes place around the centre of gravity. This arises from the fact that the resultant of the charge acts at the centre of figure, while inertia, or resistance to motion, acts at the centre of gravity. The axis of rotation passes through the centre of gravity, and is perpendicular to a plane containing the resultant of the charge and the centres of figure and gravity. For the same charge, the velocity of rotation is proportional to the lever arm, or perpendicular, let fall from the centre of gravity to the resultant of the charge. Knowing the position of the centre of gravity of the ball in the bore, it is easy to foretell the direction and velocity of rotation. In general terms, the front surface of the projectile moves toward the side of the bore on which the centre of gravity is situated, and the velocity of rotation is greatest when the line joining the centres of gravity and figure is perpendicular to the axis of the bore. The position of the centre of gravity of a projectile is -found by floating in a mercury bath; and by an instrument called the eccentromete%. The topmost point of the surface, when the projectile has settled to a state of rest in the bath, marks one point at which the line joining the centre of gravity and figure pierces the surface; the position of the centre of gravity along this line is determined by the eccentrometer, which is a peculiar kind of balance. w being the weight of the projectile, and x the distance of its centre of gravity from the fulcrum of the balance, and w' being the weight necessary to balance the projectile, and a its distance from the fulcrum, we have, from the equality of the moments THE EFFECT OF ROTATION. 427 caw' aw =uwx, or x=. The position of the projectile.on the balance being known, by placing the marked point on the surface nearest the fulcrum, the position of the centre of gravity becomes known; for if b be the' distance of the marked point from the fulcrum, and r the radius of the projectile, x-b-r is the distance between the centres of gravity and figure. 430. The effect of rotation. The effect of rotation in producing deviation, may be studied under three heads: 1st. When the projectile is spherical and concentric. 2d. When it is spherical and eccentric; and 3d. When it is oblong. Concentric projectiles. The simplest case is that of a homogeneous spherical projectile, rotating around a vertical axis passing through the centre of gravity. Let A B CvD represent the great circle cut out of the sphere perpendicular to the axis of rotation, and suppose rotation to take place in the direction A C B, and'the motion'of translation in the direction A B; it is evident that each point of the circle moves in the direction A B, with a ve- Fig. 138. locity which is equal to the velocity of translation, plus or minus the component of its velocity of rotation in the direction of the axis A B, which is equal to the projection of the arc over which the point moves in a unit of time, on the line A B. The points C and D have the greatest velocity in the direction of this line; A B, and the points A and B the least. All the points 428 SCIENCE OF' GUNNERY.-DEVIATION OF PROJECTILES. in the semi-circle A CU B rotate in a forward direction, and the components of their velocities of rotation must be added to that of translation; while the points in the semicircle B D A move backward in rotation, and the components of their velocities must be subtracted from it. A body moving in the air draws with it a film of the particles which surround it, and these particles set in motion the adjacent particles, and so on from one layer to another; the number of particles set in motion and their reaction on the surface of the projectile, depend on the velocity of the moving surface; now it has been shown that the surface A C B moves with a greater velocity than the opposite side, the reaction, or pressure upon it, must be greater than upon the latter, and the projectile will be urged in the direction D. Eccentric projectile&. Let A C B D represent the great circle cut out of an eccentric projectile perpendicular to the axis of rotation, and containing the centre of figure 0, and the centre of gravity 0'. Suppose the motions of rotation and Fig. 139. translation to take place as in the preceding case, it follows that the same cause will operate in this, as in the preceding case, to deviate the projectile in the direction CD; but there is another and more powerful cause operating to deviate the projectile in the same direction, and that is, the greater pressure on the side A CUB arising from the greater surface offered to the air in consequence of the eccentricity. Prof. iagnus' appcaratus. These phenomena may be THE EFFECT OF ROTATION. 429 easily illustrated b)y the very simple and ingenious apparatus devised by Prof. Magnus, of Berlin. Let C(fig. 140) represent a light brass cylinder, delicately suspended in a ring, and made to revolve rapidly around its vertical axis, by means of a string, after the manner of a top; let this ring be suspended at the extremity of a wooden'lever B', which, in turn, is suspended by a delicate Fig. 140. wire from the ceiling, so that it may rotate freely in a horizontal direction; let P be a counterpoise, and R the direction of a strong current of air blowing upon the cylinder from a fan-blower. It is invariably found, that the axis of the cylinder will move in the opposite direction from the side which is moving toward the current of air from the blower (see direction of the arrows); but if there be no rotation of the cylinder, the axis will remain stationary. Conclu8ions. If a projectile be spherical and concentric, rotation takes place from contact with the surface of the bore around a horizontal axis, and the effect will be to shorten or lengthen the range, as the motion of the front surface is downward or upward. If the projectile be eccentric, the motion of the front surface is generally toward, the side on which the centre of gravity is situated, and the deviation takes place in this direction. The extent of the deviation for the same charge, de. pends on the position of the centre of gravity; the horizontal deviation being the greatest when the centres of gravity and figure are in a'horizontal plane, and the 430 SCIENCE OF GUNNERY.-DEVIATION OF PROJECTILES. line which joins them is at right angles to the axis of the piece; the vertical deviation will be the greatest when these centres are in a vertical plane, and the line which joins them is at right angles to the axis of the piece. If the axis of rotation coincide with the tangent to the trajectory throughout the flight, all points of the surface have the same velocity in the direction of the motion of translation, and there will be no deviation. This explains why it is that a rifle-projectile moves through the air more accurately than a projectile from a smooth-bored gun. In the experiments of Major Wade with 32-pdr. fieldshells, made purposely eccentric, the difference of the extreme lateral deviations, produced by placing the centre of gravity first on one side and then on the other, amounted to 100 yds., or one-fourth of the entire range. The experiments of Captain Dahlgren with service 32pdr. balls, show the following results when the centre of gravity is* placed in different positions in the vertical plane through the axis of the bore. POSITION OF CENTRE OF GRAVITY IN VERTICAL PLANE. 90~ up. 90~ down. Inward. 450 up. and in. 1415 yds. 1264 yds. 1329 yds. 1360 yds. In accurate firing, therefore, it is important to know the true position of the centre of gravity: in ricochet firing over smooth water, the number of grazes may be increased or diminished by placing, in loading, the centre of gravity above or below the centre of figure. The first person to call attention to the deviation DEVIATION OF OBLONG PROJECTILES. 431 produced by rotation, was Robins, who illustr'ated it by bending a musket-barrel to the right, and firing through a succession of paper screens; the projectile was observed to deviate, first to the right, in the direction in which the muzzle was pointed, and then to the left, in the opposite direction from the side of the projectile which rotates toward the front. 431. Deviation of oblong projectiles. The cause of the deviation of an oblong rifle projectile is quite different from one of spherical form. An oblong projectile moving in the air is acted upon Fig. 141. by two rotary forces, viz.; one which gives it its normal rotary motion around its axis of progression, and another the resistance of the air, which, in consequence of the deflection of the axis of progression from the tangent to the trajectory by the action of gravity, does not pass through the centre of inertia, but above or below it, depending on the shape of the pro. jectile. From a law of mechanics, a body thus circum. stanced, will not yield fully to either of the forces that thus act upon it, but its apex will move off with a slow uniform motion to the right or left of the vertical plane, depending on the relative direction of the two rotary forces. If the action of these forces be continued sufficiently long, it will be seen that the axis of the projectile before referred to, describes a cone around a line passing through the centre of inertia and parallel to the direction of the resistance of the air. Owing to the short duration of the flight of an ordinary projectile, it is only necessary to consider the first' part of this conical motion. If the projectile rotates in 432 SCIENCE O1 GUNNERYi-DEVIATION OF PROJECTILES. the direction of the hands of a watch to the eye of the marksman, and the resultant of the resistance of the air pass above the centre of inertia, as it does in -the' service bullet with a conoidal point, see fig. 141, then the:pointof the projectile will move to the right, which brings: the left side of the projectile obliquely in contact with the current of the air. The effect of this position withreference to the -air, will be to generate a component force that' will urge the projectile to the right of the plane of fire, as a vessel sailing on the wind has a mo-, tion to the leeward,. If the bore be grooved with a left-handed twist, thei deviation will be to the left of the plane of' fire, as has been shown by actual experiment. This peculiar devi-. ation was called by the French officers that first observed it, "drivation" or " drift." That it is not produced by the effect of the recoil on the shoulder of the m'arksman, as some assert, is shown by the fact that drift increases more rapidly than the distance. The following table gives the drift at different distances, for the French rifle, model of 1842, with a twist of 4.37 feet, and a bullet with a single groove: Distanrdesin 218 328 437 546 656 765 874 984 1093 1312 1421 yards. Draniftinfet.5"11'.1" 1'.9" 2'.0" 4'.9" 71.6" 11.6"16'.1" 21'.0" 38'.4" 50'.6" and inches. In consequence of the reduced calibre and twist, the drift of our present rifle-musket projectiles is less than the foregoing. The -mean drift of 40 -shots fired from two service rifle-muskets, at a distance of 1,150 yds., in SUMMARY OF DEVIATING CAUSES. 433 a perfectly calm day, was about 18 feet; not a single shot deviated to the left of the point aimed at.* Effect of wind. The deviating effect of wind depends on its force, and its direction with regard to the plane of fire; generally speaking, large and heavy projectiles, moving with high velocities, are deviated less than those of contrary character. It is difficult to calculate the effect of the wind in any particular case; in making allowance for it, therefore, the gunner should be guided by experience and judgment. For the same projectile, velocity, and wind, the deviation varies nearly as the square of the range. 432. Summary of deviating causes. The following summary may be considered as embracing nearly all the causes of deviation of cannon and small-arm projectiles. 1st. From the construction of the piece. These causes are, wrong position of the sight; bore not of the true size; crooked barrel; too hard on the trigger; windage; the recoil; and spring of the barrel. 2d. From the charge of powder. Improper weight; form of grain and variable quality of the powder; injury from dampness; more or less ramming; sticking along the bore from foulness and dampness. 3cld. From the projectile. Not of the exact size, shape, or weight; disfiguration in loading, oi on leaving the bore; eccentricity. 4th. From the atrnosphere, &e. The effect of wind; variations in the temperature, moisture, and density of * The subject of drift has been fully exposed in a learned analytical investigation by General Barnard, of the engineer corps, who shows that it is a particular case of the gyroscope. It has also been explained experimentally by Professor Magnus, of Berlin, a copy of whose apparatus may be found in the Museum of the United States Military Academy. 28 434 SCIENCE OF GUNNERY.-DEVIATION OF PROJECTILES. the air; position of the sun as regards the effect on the aim; difference of level between the object and piece; and rotation of the earth. The latter source of deviation arises, 1st. From the fact that all points on the surface of the earth, not in the same parallel of latitude, move with different angular velocities; and 2d. That when a body is thrown from one point to another, it carries with it the angular velocity with which it started. Applying these facts, it is found that a projectile will deviate to the right of the object, whatever may be the direction of the line of fire, and at a distance from it, depending on the latitude of the place, and on the time of flight and the range of the projectile. Poisson has shown that a 12-inch shell weighing 200 lbs., fired under an angle of 450, with an initial velocity of 900 feet, will deviate from 15 to 20 feet to the right of the object-the range being about 4,400 yards. USE OF PROJECTILES NOT SUITED TO THE BORE. 435 CHAPTER IX. LOADING, POINTING, AND DISCHARGING FIREARMS. 433. Loading. In loading guns and howitzers, the powder is carefully put up in a cartridge-bag of woollen cloth, which is either attached to, or carried separate from the projectile, depending on the weight of the projectile. In ramming a charge, only a sufficient force should be used to send it home, as the space which the powder occupies affects the initial velocity. In loading mortars, the powder is poured from the cartridge-bag into the chamber, and levelled with the hand; the shell is then carefully lowered upon it with the hooks. 434. Precautions. After a piece has been discharged the bore should be well sponged, to extinguish any burning fragments of the cartridge that may remain; and to, prevent the current of air from fanning any burning fragments that may collect in the vent, it should be kept firmly closed with a thumb-stall in the operation of sponging. Experience shows that the use of a wet sponge is dangerous, as it contributes to form, from the fragments of the cartridge-bag, a substance which retains fire. 435. Use of projectiles not suited to the bore. It may be sometimes necessary to fire projectiles that are either very much smaller or larger than the bore. If it be desired to use a gun-shell, or solid shot, which 436 LOADING AND POINTING FIRE-ARMS. is much smaller than the bore, it is strapped to a stout sabot which fits the bore; if a mortar-shell, it is placed in the centre of the bore by means of wedges, and the surrounding space is filled up with earth. Mortar-shells are fired from guns and howitzers, by digging a hole in the ground about 20 inches deep, and placing in it two pieces of stout plank inclined at an angle of 450, for the support of the breech; the chase is supported on a movable wedge, which rests on skids firmly secured with platform stakes;* the charge of powder is then inserted in the bore, and the projectile is placed on the muzzle, and secured by passing strings over it, and tying their ends to a rope, which encircles the neck'of the chase. Pieces fired in this way should be elevated 400 or 45~; thus situated, the fuze of the 8-inch mortar-shell takes fire from very small charges; but the 10-inch fuze should be primed with strands of quick-match, which are allowed to hang over the sides of the shell. POINTING. To point or aim a fire-arm is, to give it such direction and elevation that the projectile shall strike the object. To do this properly, it is necessary to understand the relations which exist between the line of sight, line of fire, trajectory, &c. 436. Definitions. The line of sight is the right line containing the guiding points of the sights. The sights are two pieces, A and B, on the upper surface of the * Pieces that have been disabled by breaking off a trunnion, may be fired in this manner. DEFINITIONS. 437 Fig. 142. gun, the situation of which with regard to the axis of the bore is known. The front sight is situated near the muzzle, or on the right rimbase, and is generally fixed; the rear sight is placed near the breech, and is movable in a vertical, and sometimes in a horizontal direction. The natural line of sight is the line of sight nearest the axis of the piece; the others are called artificial lines of sight. The line of fire is the axis of the bore prolonged in the direction of the muzzle, or C('D. The angle of fire is the angle included between the line of fire and horizon; on account of the balloting of the projectile, the angle of fire is not always equal to the angle of departure, or projection. See section 268. The angle of sight is the angle included between the line of sight and line of fire; angles of sight are divided into natural and artificial angles of sight, corresponding to the natural and artificial lines of sight which enclose them. The plane of Jire is the vertical plane containing the line of fire. The plane of eight is the vertical plane containing the line of sight. The point-blank is the point at which the line of sight intersects the trajectory, or P. Strictly speaking, the line of sight intersects the trajectory at two points, C' 438 LOADING AND POINTING FIRE-ARMS. and P; but, in practice, the point P is only considered. The distance, B P, is called the point-blank distance. The natural point-blcank corresponds to the natural line of sight; all other point-blanks are called artificial.poilnt-blank8s. In speaking of the point-blank of a piece, the natural line of sight is supposed to be horizontal. In the British service, the point-blank distance is the distance at which the projectile strikes the level ground on which the carriage stands, the axis of the piece being horizontal. It is evident that this definition of point-blank distance conveys a better idea of the power of the piece than the' former, which makes it depend on the form of the piece, as well as on the charge. As the angle of sight A C C' is increased, the pointblank distance is increased; as it is diminished, the intersections of the line of sight and trajectory approach each other until they unite, when the line of sight and trajectory are tangent to each other; beyond this, the point-blank is imaginary. As the angle of fire increases, the force of gravity -acts more in opposition to the force of projection, and the point-blank distance is diminished, until at 900 it becomes zero. Under an angle of depression, the force of gravity acts more nearly in the direction of gravity, and the point-blank distance is increased, becoming infinite when the angle of depression is equal to 900 minus the angle of sight. In ordinary firing, it is not considered that the trajectory changes its position with reference to the lines of sight and fire, for angles of elevation and depression, less than 150. In. aiming at an object, therefore, the POINTING GUNS AND HOWITZERS. 439 angle of elevation of which is less than 15~, aim as though it were in the same horizontal plane with the piece. For the same piece, the point-blank distance increases with the charge of powder; for the same initial velocity, a large projectile has a greater pointblank distance than a small one; a solid shot than a hollow one; an oblong projectile than a round one; or, in other words, it varies with the value of c, before referred to. _Range is the distance at which a projectile first strikes the ground on which the carriage is situated; extreme range is the distance to the point at which the projectile is brought to a state of rest. 437. Pointing guns and howitzers. In pointing guns and howitzers under ordinary angles of elevation, the piece is first directed toward the object, and thein elevated to suit the distance. The accuracy of the aim depends —lst. On the fact that the object is situated in the plane of sight; 2d. That the projectile moves in the plane of fire, and that the planes of sight and fire coincide, or are parallel and near to each other; and 3d. On the accuracy of the elevation. The first of these conditions depends on the eye of the gunner, and the accuracy and delicacy of the sights; the errors under this head are of but little practical importance. When the trunnions of the piece are horizontal, and the sights are properly placed on the surface of the piece, the planes of sight and fire will coincide; but when the axis of the trunnions is inclined, and the natural line of sight is oblique to the axis of the bore, the planes are neither parallel nor coincident, and the 440 LOADING AND POINTING FIRE-ARMS. aim will be incorrect. If the natural line of sight be made parallel to the line of fire, by making the height of the front sight equal to the dispart of the piece, the planes of sight and fire will be parallel, and at a distance from each other equal to the radius of the breech multiplied by the sine of the angle which the axletree makes with the horizon. To show this, let the circle A C B D represent the section of the breech of the piece taken at right angles to the axis, and C the projection of the natural line of sight upon this plane; let A' B' be the inclined position of the axletree, or trunnions, C' marks the revolved position of the natural line Fig. 143. of sight, and C' D' the trace of the plane of sight, which is parallel to C6 D, the trace of the plane of fire. As the lines of sight and fire are parallel in their revolved position, the planes of sight and fire must also be parallel. The angle CO C' — BOB', therefore CC' OC' sin. BOB'. It is easily seen that with this arrangement of the front sight, the error of pointing can never exceed the radius of the breech. By an inspection of the figure, it will also be seen, that in the revolved position of the line of sight, the elevation is diminished by a small quantity, which is equal to the versed sine of the are CC'. By referring to the construction of the pendulum hausse, on page 255, we see that if its centre of motion coincide with the point C', and the scale coincide with the line C' D', the error of aiming with an artificial line of sight is practically no greater than with the natural line of sight. POINTING GUNS AND HOWITZERS. 441 If the natural line of sight be not parallel to the axis of the piece, the planes of sight and fire intersect at a short distance from the muzzle; hence, it follows, that as the object is situated in the plane of sight, the projectile will deviate from the object to the side on which the lower wheel is situated, and at a distance from it, which is proportional to the distance of the object from the piece; to correct for this source of error, the line of sight should be pointed to the side of the higher wheel, and at a distance from the object, which is proportional to the distance of the object from the piece. Siege and sea-coast cannon are generally fired from fixed platforms, which renders the axis of the trunnions horizontal; they are, therefore, not furnished with pendulum sights. In case the axis of the trunnions is not horizontal, and the piece has not a pendulum hausse, the highest points of metal'at the breech and muzzle may be determined by the gunner's level (see page 254), aind marked with chalk; the centre line of the tangent scale; or breech-sight, is placed on the mark at the breech, the slider is placed at the proper elevation, and the aim is taken along the notch of the slider and the mark on the muzzle. This method, however, does not give a perfectly accurate aim. In the absence of a breech-sight, the piece can be pointed with the natural line of sight so as to strike objects not situated at point-blank distance; if the object be within point-blank range, as at P" (fig. 142), the natural line of sight should be depressed below the object as much as the trajectory is above it; if 442 LOADING AND POINTING FIRE-ARMIS. it be beyond point-blank, as at P', the natural line of sight should be directed to a point H] which is as much above the object, as the point H', of the trajectory, is below it. Owing to the shape and size of the reinforce of seacoast cannon, the natural line of sight is formed by affixing a front sight to the muzzle, or to a projection cast on the piece between the trunnions. Although the latter arrangement does not give quite so long a distance between the sights as is desirable, it permits the use of a shorter breech-sight, and the front sight does not interfere with the roof of the embrasure, when the piece is fired under high elevation. 438. Pointing mortars and small-arms. In pointing small-arms and mortars, the piece is first given the elevation, and then the direction necessary to attain the object. Pointing mortars. Mortars are generally fired from behind epaulements, which screen the object from the eye of the gunner. The elevation is first given by a gunner's quadrant, -applied as described on page 256; and the direction is given by moving the mortar-bed with a handspike, so as to bring the line of sight into the plane of sight, which, by construction, passes through the object and the centre of the platform. The plane of sight may be determined in several ways; the method prescribed is to plant two stakes, one on the crest of the epaulement, and the other a little in advance of the first, so that the two shall be in a line with'the object, and the gunner standing in the middle of the rear-edge of the platform; a cord is attached to the second stake, and held so as to POINTING MORTARS AND SMALL-ARMS. 443 touch the first stake; a third stake is driven in a line with the cord, in rear of the platform, and a plummet is attached to this cord so as to fall a little in rear of the mortar. It is evident that the cord and plummet determine the required plane of sight into which the line of sight of the mortar must be brought. The usual angle of fire of mortars is 45~, which corresponds nearly with the maximum range. The advantages of the angle of greatest range are. Ist. Economy of powder; 2d. Diminished reeoil, and strain on the piece, bed, and platform; 3d. More uniform ranges. When the distance is not great, and the object is to penetrate the roofs of magazines, buildings, &c., the force of fall may be increased by firing under an angle of 60~. The ranges obtained under an angle of 600 are about one-tenth less than those obtained with an angle of 45~. If the object be to produce effect by the bursting of the projectile, the penetration should be diminished by firing under an angle of 30~. When the object is not on a level with the piece, the angle'of greatest range is considered in practice to be 45-+o0, or 45 -o, o being the angle of elevation or depression of the object. Thus to attain a magazine, for instance, situated on a hill, for which o0 15~, the angle of greatest range is 520o instead of 45~. The angle of fire being fixed at 450 for objects on the same level with the piece, the range is varied by varying the charge of powder. The practical rule is founded on the knowledge of the amount of powder necessary to diminish or increase the range 10 yards. For the French 8 and 10 inch siege-mortars, this amount is 444 LOADING AND POINTING FIRE-ARMS. about 60 grains for the former, and 125 grains for the latter. A practical rule for finding the time of flight by which the length of the fuze is regulated, is to take the square root of the range in feet, and divide it by four; the quotient is the approximate time in seconds. Stone-mortars are pointed in the same manner as common mortars: the angle of fire for stones is from 600 to 75~, in order that they may have great force in falling; the angle for grenades is about 33~, in order that their bursting effect may not be destroyed by their penetration into the earth. 439. Nighlt-firing. Cannon are pointed at night by means -of certain marks, or measurements, on the carriage and platform, which are accurately determined during the day. In the case of guns and howitzers, the elevation may be determined by marking the elevating screw where it enters the nut, or by measuring the distance between the head of the screw and stock. In the case of mortars, the position of the quoin may be -determined by marking, or by nailing a cleat on the bolster. The direction of a carriage or mortar-bed is determined by nailing strips of boards along the platform, as guides to the trail and wheels; to prevent the strips from being'injured by the recoil, they should be nailed at a certain distance from the carriage, or bed, and the space filled up with a stick of proper width, which should be removed before firing. The chassis of a seacoast carriage can be secured in a particular direction by firmly chocking the traverse wheels. GRADUATION OF 2EA-SIGHTS. 44 5 440. Pointing small-arms. The rear-sights of smallarms are graduated with elevation marks for certain distances, generally every hundred yards; in aiming with these, as with all other arms, it is first necessary to know the distance of the object. This being known, and the slider being placed opposite the mark corresponding to this distance, the bottom of the rear-sight notch, and the top of the front sight, are brought into a line joining the object and the eye of the marksman. The term coarse-siYght is used when a considerable portion of the front-sight is seen above the bottom of the rear-sight notch; and the term fne-sight, when but a small portion of it is seen. The graduation marks being determined for a fine-sight, the effect of a coarse-sight is to increase the true range of the projectile. 441. Graduation of rear-sights. If the form of the trajectory be known, the rear-sight of a fire-arm can be graduated by calculation; the more accurate and reliable method, however, is by trial. Suppose it be required to mark the graduation for 100 yards; the slider is placed as near the position of the required mark as the judgment of the experimenter may indicate; and, with this elevation, the piece is carefully aimed, and fired, say ten times, at a target placed on level ground, at a distance of 100 yards. If the assumed position of the slider be correct, the centre of impact of the ten shot-holes will coincide with the point aimed at; if it be incorrect, or the centre of impact be found below the point aimed at, then the position of the slider is too low on the scale. Let P be the point aimed at, and P' the centre of impact of the cluster of shot-holes; we have, from close similarity of the triangles, A'F: F2P.-. 446 LOADING AND POINTING FIRE-ARMS. Fig. 144. A'A": PP', from which we can determine A'A", the quantity that must be added to AA', to give the correct position of the graduation mark for 100 yards. If the centre of impact had been above P, the trial mark would have been too high. Lay off the distance AA" above A", on the scale, and we obtain an approximate graduation for 200 yards, which should be corrected in the same way as the preceding, and so on. The dis. tance PP' is found by taking the algebraic sum of the distances of all the shots from the point P, and dividing it by the number of shots. It will be readily seen that an approximate form of the trajectory may be obtained.by drawing a series of lines through the different graduation marks of the rear-sight, and the top of the frontsight, and laying off from the front-sight, on each line, the corresponding range. The points thus determined are situated in the required trajectory. 442. Distance of object. Various instruments have been devised to determine the distances of objects, based on the measurement of the visual angles subtended by a foot or cavalry soldier, of mean height, at different distances; but these instruments are considered of little practical value, especially in the excitement of action. Every officer and soldier should be taught to estimate distances by the eye, and in so doing much assistance is derived from knowing what parts of a soldier's dress, or equipments, are visible at certain distances. These data vary with the power of the eye, and each soldier should TABLES OF FIRE. 441 be required, by comparison and reflection, to create a standard for his own. In firing cannon, the point at which the projectile strikes the ground or bursts, can generally be observed, and from it, the error of aim can be corrected in a few fires; this, however, does not hold true for small-arm projectiles, which are seldom seen to strike the ground, unless the soil be dusty. In the defence of sea-coast batteries, the distances of objects may be determined by their proximity to known objects, as fixed buoys, or by their bearing with reference to prominent landmarks. Plane-tables may be also used to determine the distances of objects. The degree of accuracy with which the distance of an object should be known, depends somewhat on the size of the object and the inclination of the trajectory to the line of sight; if the object be large and the trajectory vary but slightly from the line of sight, it is not necessary to know the exact distance, provided the aim be accurately taken. TABLES OF FIRE. 443. Purpose. The nature and purpose of a table of fire should be explained in connection with the subject of pointing cannon. A properly constructed table of fire, for a particular piece, contains the range and time of flight for each elevation, charge of powder, and kind of projectile. Its purpose is to assist the artillerist in attaining his object without waste of time and ammunition, and also when the effect of shot cannot be seen on account of the dust and smoke of the battle 448 LOADING AND POINTING FIRE-ARMS. field. The first few shots generally produce a great effect on the enemy, and it is very important that they should be directed with some knowledge of their results, which, in the field, can only be attained by experience, or from the data afforded by a table of fire. The following is the form of a table of fire for guns and howitzers::RIND OF POWDER. PROJECTILE. ELEVATION. RANGE. TIME. ORDNANCE. Lbs. Lbs. o, Yards. Sec'ds. 38 29, (solid.) 50 0' 2099 7.5 70 0' 2894 9.1 100 0' 3700 11.6 Armstronggun, 120 0' 4196 14.2 4-inch bore. 150 0' 4776 17.1 200 0' 6070 21.4 250 0' 6580 25. 300 0' 7555 31. 350 0' 9000 The ranges in the foregoing table were determined at West Point, in 1860, and are the mean of five shots for each angle of elevation. The ranges obtained with the best American muzzle-loading rifle.cannon compare favorably with these. Tables of fire, for the different service cannon, may be found in the Ordnance and Artillery Manuals,' and the XIII. chapter of this work. RAPIDITY OF FIRE. 444. Depends on size of piece, &c. The rapidity with which cannon can be loaded and discharged depends on the size of the piece, the construction of the carriage, and the care required in aiming. DEPENDS ON SIZE OF PIECE, ETC. 449 Fielcl-canznon. Field-cannon can be discharged with careful aim, about twice per minute; in case of emnergency, when closely pressed by the enemy, canister-shot may be discharged four times per minute. The 12-pdr. boat-howitzer of the navy, with experienced gunners, can be discharged at the rate of sixteen times per minute. Sieye-cannon. Siege-guns are generally discharged about twelve times per hour; if necessary, they can be discharged as rapidly as twenty times per hour. Iron cannon can be fired more rapidly than bronze, as the latter metal is softened by the heat, and the piece is liable to bend. Siege-mortars can be conveniently fired twelve times per hour, and more rapidly than this if the object be large, as a city. Siege-howitzers can be fired about eight times in an hour.,Sea-coast cannon. The fire of a sea-coast cannon depends much on the ease with which its carriage can be manceuvred. The heaviest, or 15-in. gun, mounted on the new iron carriage, can be loaded and fired in 1' 10"; the time required in aiming depends on the angle through which the chassis is to be traversed, and piece elevated, or depressed; it can be traversed through an angle of 90~ in 2' 20". Srncal-arms. Muzzle-loading small-arms can be discharged two or three times in a minute, and breech-loading arms about ten times; the revolver can be discharged much more rapidly for six shots. This quality of a military fire-arm should be carefully guarded, as it is found that soldiers are prone to discharge their pieces in the excitement of battle without taking proper aim, and consequently to waste their ammunition. 29 450 DIFFERtNT KINDS OF FIRPES. CHAPTER X. DIFFERENT KINDS OF FIRES. 445. Classification. Artillery fires are distinguished by the manner in which the projectile strikes the object-as direct, ricochet, rolling, and plunging fires; by the nature of the projectile, as solid shot, shell, shrcpi)nel, graipe, and canister fires; and by the angle of elevation, as horizontal fire, or the fire of guns and howitzers under low angles of elevation, and vertical fires, or the fire of mortars, under high angles of elevation. 446. Direct fire; A fire is said to be direct when the projectile hits its object before striking any intermediate object, as the surface of the ground, or water. This species of fire is employed where great penetration is required, as the force of the projectile is not diminished by previous impact; it is necessarily employed for spherical-case shot, and for rifle-calnnon projectiles, which, from their form, are liable to be deflected, by previously striking a resisting substance; it is also used for all field-cannon projectiles, when the nature of the ground does not insure a regular rebound. To point a piece ina direct fire, bring the line of sight to bear upon the object, and then elevate the piece according to the distance. 447. Ricochet fire. When a projectile strikes the ground, or water, under a small angle of fall, it penetrates obliquely to a certain distance, and is then re. RICOCHET FIRE. 451 flected at an angle greater than the angle of fall; the reason for this is, that the projectile, in forming the furrow, loses a portion of its velocity, making the distance from A (fig. 145), the point at Fig. 145. which it enters the ground, to C, or the vertical drawn through the deepest point, greater than the distance from C to D, the point where it leaves the ground. As this recurs every time the projectile strikes the ground, it follows that the trajectory is made up of a series of rebounds, or ricochets, each one shorter and more curved than the preceding one. The number, shape, and extent of the ricochets, depend on the nature of the surface struck, the initial velocity, shape, size, and density of the projectile, and on the angle of fall. A spherical projectile ricochets well on smooth water, when the angle of fall is less than 80, but if the surface of the water be rough, very little dependence can be placed 9n the extent of the ricochet. Captain Dahlgren cites ia case as coming under his observation where the distance between the first and second rebound was increased from 400 to 800 yards by a strong wind; at the same time, the height of the highest point of the curve was increased from a very small distance above the water, to more than 50 feet, which would have rendered it ineffective against the hull of a ship. From the saime causes the lateral deviations in ricochet fire will be very considerable,: amounting, in some cases, to between 100 and 200 yards in the entire range. In general, those projectiles which present a uniform 452 DIFFERENT KINDS OF FIRES. surface, and have the least penetrating power, are most suitable for ricochet firing; hence, large shells fired with small charges are more suitable than solid shot, and round projectiles more suitable than those of an oblong form. The distance at which the larger size shells will ricochet on water is about 3,000 yards, the axis of the piece being horizontal and near the water. VWhere used, &c. Ricochet fire is employed in siege operations to attain the face of a work in flank, or in Fig. 146. reverse (see fig. 146), and on the field, or on water, when the object is large and its distance is not accurately known. The character of ricochet fire is determined by the angle of fall, or the angle included between the tangent of the trajectory and horizon at the point of fall. There are two kinds of ricochet fire-the flattened, in which the angle of fall is between 20 and 40; and the curvated, in which the angle of fall is between 60 and 15~. The principal pieces employed in ricochet fire in siege operations are the 8-inch howitzer, and the 8 and 10-inch common mortars; the first two may be used when the angle of fall is less than 10~, and the 10-inch mortar when the angle of fall' is less than 150-the proper elevation being given to the mortar by raising the rear portion of the bed. With these pieces, the PRACTICAL RULES FOR RICOCHET FIRE. 453 limit of ricochet is about 600 yards. Solid shot should not be used in ricochet fire for any distance less than 200 yards, as it would then be necessary to diminish its velocity so much as to destroy its percussive effect. In ricochet firing against troops in the open field, the' angle of fall should not exceed 30~. 448. Practical rules for ricochet fire. In enfilading the face of a work, the form of the trajectory and, point of fall should be such that the projectile will strike the surface of the terreplein the greatest number of times; the object being to destroy the men, carriages, and traverses situated upon it. To do this, the projectile should be made to graze the crest of the adjacent parapet, and strike the terreplein as near the foot of the interior slope as possible; the distance of the crest, and its height above the terreplein and battery, should therefore be known. The formulas in chapter VIII. furnish accurate means for calculating the various elements of ricochet fire, but they are too complicated for use in the field; it is therefore proposed to deduce simple and practical rules for this purpose. 1st. To find the anyle of arriCal. The angle of arrival is the angle which the tangent to the trajectory at the crest of the parapet makes with the horizon. Let A be the crest, and B the point of fall (fig. 14it); the distance A B being short, the portion of the trajectory included beFig. 147. tween these two points may be considered a right line, and the angle of fall 454 DIFFERENT KINDS OF FIRES. and arrival will be equal. Calling a the angle of fall, and erecting the perpendicular -B C, we have, 2Bd tan. a - C or, the tangent of the angle of crritval is equcai to the vertical dietaCnce of the point of fall below the creet, divided by the horizontal distacnce. Within the limits of ricochet fire, the angles may be supposed proportional to their tangents; calling the tangent of 60 (which is 0.1051) 0.1, we have the following proportion: BC~ YB or, a 60oBC or, the angle of arrival is eucal to 600 multiplied by the ratio of the horizontal and vertical distances of the point offcallfrom the cres-t of the parapet. This rule gives the angle of arrival without the aid of a table of natural tangents. 2 d. To ind the angle of fire. The distance of the parapet is always known, and the angle of elevation of the crest can be determined by sighting along the long branch of a gunner's quadrant, and observing the position of the plummet on the arc. In consequence of the nearness of the object, and the large size and low initial velocity of the projectile, the resistance of the air in this species of ricochet fire may be neglected, which makes the trajectory a parabola. In this case the angle of fall is equal to the angle of fire, when the object is situated in the same horizontal plane PRACTICAL RULES FOR RICOCHET -FIRE. 455 with the piece; if it be not in the same horizontal plane, let B A M (fig. 148), which is the angle of elevation Fig. 148. of the crest, be represented by e. As the angle e is very small, we are at liberty to suppose CA B=A B C. Through the point B draw the horizontal line B D, the angle C B D is equal to the angle of arrival a; the lines B D and A Mbeing parallel, the angle A B D=e; therefore C A B - CB A=ca+e, but the angle CA if CA B2+e=aS+2e: or, the angie of fire is equal to the angle of arrival increa.sedl by twice the angle of elevation of the crest of the parapet. From the erroneous suppositions made in the course of the preceding demonstrations, it will be seen that the rules deduced should give too great an angle of fire. In practice,' this angle should be somewhat greater than the true angle, in consequence of the deviations, which render the projectile liable to strike against the parapet, and, of course, destroy its effect. 3d. Tofind the charge. When a projectile moves in vacuo, we have seen that the distance which it falls below the line of fire, in the time t, is I gt2; and for a given distance, t is inversely proportional to the initial velocity V; hence the distances which the same projectile, fired with different velocities, would fall below the line of fire, in the distance A Cv (fig. 149), will be inversely proportioncal to the squares of the initial v)eloci ties. 456. DIFFERENT KINDS OF FIRES. Fig. 149. If we suppose the lines of fire of two projectiles be A C and A C', and the initial velocities, V and V', to be such that they will fall the distances B C and B' C' and that the angles subtended by these lines be proportional to the lines themselves, we shall have B A C: B'A C':: V'2: V2. It has been seen that the initial velocities of small charges are nearly proportional to the square roots of the weight of the charges. Calling the corresponding charges C and C', we have B A C: B' A C':: C: C, or, for the same distance of the object, the charges should be inversely proportional to the difference between the angle of fire and angle of elevation of the olbject. Take the case in which the objects are situated at different distances, as B and B" (fig. 149), but have the same angle of elevation e; and suppose we wish to strike them with the same angle of fire; what should be the relation between the charges? Substitute in the expression ~gt2, the value of t, which is D, in which D is the distance, and Vthe initial veis locity of the projectile, we have q-,- which shows that the distance which a projectile falls below the line of fire is directly proportional to the square of the distance measured on the line of fire, and inversely pro PRACTICAL RULES FOR RICOCHET FIRE. 457 portional to the square of the velocity. But the distances B" C" and B C are proportional to A C" and A (, or D)" and D), and, recollecting that the squares of the initial velocities are proportional to the charges a and Ca", we have.D"2 DC or, or, for the same difference between the anale of fie and the angle of elevation of the object, the charges are proportional to the distances. In arriving at the foregoing rules, we have committed three errors: 1st. Supposing the sides of the triangles proportional to the angles. 2d. Considering the resistance of the air nothing; and, 3d. That the initial velocities are proportional to the square roots of the charges. The errors resulting from these suppositions are not only small in themselves, but the 2d and 3d are of a nature to counteract each other. By means of the foregoing relations suitable charges can be calculated for every case of practice, when we know the charge corresponding to a given distance, and to a given difference between the angle of fire and the angle of elevation of the object. Represent by C' the charge corresponding to a distance, D', and to a difference, E', between the angle of fire and the angle of elevation of the object; we have the charge, C, corresponding to the distance, D, and the difference, ]E be. tween the two angles, by means of the formula _D C' E BX 1 458 DIFFERENT KINDS OF FIRES. The factor, is a constant number for each calibre. This number may be considered as the charge corresponding to the distance of 1 yard, and to a difference of 10 between the angle of fire and of elevation of the object. For the French 8-inch siege howitzer, the value of this factor has been found by careful experiment to be 0.31 oz. Making an allowance for difference of weight of projectile and unit of distance, it becomes 0.28 oz. for the American 8-inch siege howitzer. Examnple.-Find the angle of arrival, angle of fire, and charge of powder, necessary to hit, with an 8-inch howitzer shell, a point on a terreplein, 12 yards behind a traverse which is 2.5 yards high and 350 yards from the battery-the angle of elevation of the crest being 1~, and the command 6 yards. For the angle of arrival we have BC 60~x2.5 a —60~AB -12 120 30'; a 60 1B 12 For the angle of fire we have P=;a + 2e=12030'+ 2= 14~ 30'. For the charge we have D 350. C —0.28 oz. = 0.28=7.25 oz. _E 13.5 449. Rolling fire. Rolling fire is a particular case of ricochet fire, produced by placing the axis of the piece parallel, or nearly so, with the ground. It is generally used in field service. When the ground is favorable for ricochet, the projectile, in rolling fire, has a very long range, and never passes at a greater distance above the ground than the muzzle of the piece; it is therefore more effective than direct fire, as may be seen by inspecting fig. 150. EFFECT OF FIRE IN GENERAL. 459 Fig. 150. To point a piece in rolling fire, direct it at the object, and depress the naturalJ line of sight so as to pierce the surface of the ground about 80 yaCrdS in front of the. muzzle; if the piece be sighted for the pendulum hausse, aim directly at the object with the lowest line of sight, or with the slider fixed at the zero point of the scale. 450. Plunging fire. A fire is said to be plunging when the object is situated below the piece. This fire is particularly effective against the decks of vessels. 451. Effect of fire in general. Before proceeding to describe the fires of different kinds of projectiles, it may be proper to explain what is meant by accuracy of fire, and to determine a suitable measure for it. It has been seen that there are causes constantly at work to deviate nearly every projectile from its true path. As the effect of these deviating forces cannot be accurately foretold, there ig only a probability that the projectile will strike the object against which the piece is pointed. The degree of probability is called accuracy of fire. For all projectiles of the same nature, the chance of hitting an object increases with the velocity and weight of the projectile, whereby the effects of the deviating forces are diminished; it also increases as the size of the object is equal to, or greater than, the mean deviations, and as the trajectory more nearly coincides with the line of sight, If the size of the object be greater than the extreme deviation, and the trajectory coincide with the 460 DIFFERENT KINDS OF FIRES. line of sight, the projectile will be certain to hit the object at all distances. 452. Measure of deviation. For the same trajectory, therefore, the mnean deviation of a projectile at a given distance may be taken as an indirect measure of its accuracy at this distance. To obtain this mean deviation, let the piece be pointed at the centre of a target, stationed: at the required distance, and fired a certain number of timessay ten and let the positions of the shot-holes, measured in vertical and horizontal directions, be arranged in the following tabular form: Distances from centre of target, in feet. Distances from centre of impact, in feet. Vertical. Horizontal. Vertical. IIorizontal. Above. | Below. Right. Left. Above. Below. Right. Left. 1 1 3 4 4.33 2.66 2 6 2 4.66 3.33 3 1 2.33.66 3 7 6 2 4.66 4.66 3.33 3.33 4 3-1.33 j4 -- 31.33 9.32 — 3 3.11 6.66- 3=-2.22 The algebraic sum, of the distances in each, direction, divided by the number of shots, gives the position of the centre of impact in this'direction. In the above table the position of the centre of impact is found to be 1.33 ft. below, and 1.33 ft. to the right, of the centre of the target. To obtain the mean deviation, it is necessary to refer each shot-hole to the centre of impact as a new origin of co-ordinates; and this is done by subtracting the tabular distance from the distance of the centre of impact, if both be on the same side of the DEVIATIONS. 4(61 centre of the target, and adding them, if on different sides. The sum of all the distances thus obtained in one direction, divided by the number of shots, gives the mean deviation in that direction; which in the present case is 3.11 ft. vertically, and 2.22 horizontally. The foregoing affords a measure for the accuracy of fire of the piece and projectile, but it does not afford a measure for marksmanship, the object of which is to direct a projectile so as to strike a given point or surface. In target-practice with sporting rifles, the string, or sum of the distances of a certain number of shots, from the point aimed at, is taken as the measure of accuracy. In military arms, marksmanship is measured by the greatest number of projectiles out of a certain number, placed in a target of given size, or placed within a given space surrounding the centre of the target. 453. Targets. Targets for heavy cannon are made of cotton cloth (or light boards) stretched over two upright poles firmly secured in the ground. The size varies with the distance: for 1,000 yards and upward, it should be about 20 feet high and 40 feet long. Targets for the field service are made of the same materials, about 8 feet' high, and from 30 to 40 feet long. Targets for small arms, if permanent, are made of cast-iron; if portable, -of a wrought-iron frame covered with cotton cloth. For distances less than 200 yards, they should be 6 feet high and 22 inches broad; beyond this distance, the breadth of a target may be increased by placing two or more of these targets side by side. 454. Deviations. The vertical deviation of a projectile is generally greater than its corresponding hori 462 DIFFERENT KINDS OF FIRES. zontal deviation, and this difference increases with the range. As objects against which military projectiles are directed, present a greater extent of surface in a horizontal than in a vertical direction, it becomes necessary to exercise great care in the selection of the proper angle of fire. If the ground or water in front of the object be favorable to ricochet, the difficulty will be diminished by aiming so that the projectile will strike the object after one or more rebounds. 455. Solid-shot firing. Solid shot are generally used for percussion and penetration, and, when heated to a red heat, for the purpose of setting fire to wooden vessels or buildings. From their great strength, they can be fired with a large charge of powder, which gives them great initial velocity, and having great density, which diminishes the effect of the resistance of the air, they have great range and accuracy. In firing hot shot, the charge should be reduced, to pre. vent too great penetration, which would exclude the air and render combustion impossible. The extreme range of field artillery is about 3,000 yards; it is not very effective, however, beyond 1,700 yards for the 6-pdr., and 2,100 yards for the 12-pdr. At 600 yards the horizontal deviation of the 12-pdr. is about 3 feet, and at 1,200 yards it is about 12 feet. For the 6-pdr. the deviations are somewhat greater at both distances. The service of solid shot demands less skill than that of shells and spherical case-shot, and they are often effective when the latter are rendered non-effective by untimely explosion. 456. slell-firing. The diameter and velocity of two SHELL-FIRING. 463 projectiles being the same, the retarding effect of the air is inversely proportional to their weight (see page 406); hence a shell has less accuracy and range than a solid shot of the same size, in the proportion of 3 to 2-these numbers representing the weights of a solid shot and shell, respectively. Field 8hells. As shells act both by percussion and explosion, they are particularly effective against animate objects, earthworks, buildings, block-houses and shipping, posts and villages occupied by troops, and against troops sheltered by accidents of the ground; but against good masonry they have but little effect, as they break on striking. Against troops, especially cavalry, they possess a certain moral effect which solid shot do not possess. They are used to form breaches in intrenchments, in which case they act as small mines. The 32-pdr. shell is the most effective field projectile for this purpose; and, when fired with a large charge, has a penetration of from 5 to 8 feet in fresh earth. The extreme range of field shells is from 2,500 to 3,000 "yards. The 24 and 32-pdr. shells burst into about eighteen effective fragments, some of which are thrown to a distance of 600 yards. All field shells have considerable lateral deviation; it is stated that the 24-pdr. shell is sometimes deviated as much as 30 yards in 1,200. fotit;ntcin s8zells. The extreme range of the mountain howitzer is about 1,200 yards, after three or four rebounds. The 12-pdr. shell employed in this service bursts into twelve or fifteen fragments, some of which are thrown to a distance of 300 yards. 464 DIFFERENT KINDS OF FIRES. Siege.shell. The great weight of an 8-inch shell, and the large quantity of powder which it contains, render it a very formidable projectile against the traverses and epaulements of siege works. Sea-coat shells. In sea-coast defence, the 8, 10, and 15-inch shells are very destructive to vessels built of timber. They range from 3 to 38 miles; but the angle which the trajectory makes with the line of sight at this distance (about 400) renders their fire very uncertain against individual objects of the size of a ship; but it is presumed that they would have the effect to prevent a blockading fleet from lying at anchor within their range, as it is well known that a single 10-inch shell, striking on the deck of a vessel, has sufficient force to penetrate to the bottom and sink her. The 8-inch shell bursts into 28 or 30 fragments;, and from the experiments made at Brest, some years ago, it was inferred that three of four of these shells, properly timed and directed, were capable of disabling a ship of war. Morta- s8hell~s are employed to break through the roofs of magazines, &c., and to blow them up; to destroy the surface of the terrepleins, ditches, &c., by forming deep hollows, which are produced by explosion, and to interrupt the communications from one part of a work to another. The great depth to which mortar shells penetrate in earth, almost entirely destroys the effect of their fragments; some remain buried in the ground, and the others are thrown out at too high an angle to be dangerous. One of the principal objects of traverses, on a terreplein, is to confine the bursting effects of shells within narrow limits. Mortar shells penetrate from half a yard to one yard in earth; and the amount of SHRAPNEL FIRING. 465 earth thrown up by explosion is about one cubic yard for each pound of the bursting-charge. Ordinarily, the;diameter of the crater at the top is two or three times the depth. The 13-inch shell will often break in falling on a pavement. Roofs of good masonry, little more than a yard thick, are sufficient to resist the penetration of mortar shells. The effect of mortar-firing is generally in favor of the besiegers, as the works of the besieged present a larger and more favorable surface for the action of shells. About one-fifth of the shells fall inside of a demi-lune at a distance of 650 yards, and about one-third at a distance of 450 yards. The line of fire should be taken in the direction of the greatest extent of the part to b)e shelled. The fire of mortars at sea is very uncertain, unless the object be very large. Stone mortars. The charge of a stone mortar should. be small, to prevent the stones and grenades from being too much scattered. A charge of stones is generally scattered over a space varying from 30 to 50 yards broad, and from 60 to 100 yards long. The dispersion of grenades is somewhat less than this; the larger portion, however, are found within a radius of 12 or 15 yards. Each grenade furnishes from 12 to 15 fragments.:in a radius of 10 or 20 yards; some of the fragments are projected to a distance of 300 yards. 457. Shrapnel firing. When a shrapnel or case-shot bursts in its flight, the fragments of the case and the contained projectiles are influenced by two forces, viz., the force of propulsion, which moves each piece in the direction of the trajectory, and the force of rupture, which moves it in the direction of a normal to the sur30 466 DIFFERENT KINDS OF FIRES. face of the case. The path described by each fragment, and projectile depends on the angle which the normal makes with the trajectory, and on the relative velocities Fig. 151. generated by the two forces; and, when taken together, these paths form a species of cone, called the cone of dispersion, the apex of which coincides with the point of rupture, and the axis is the trajectory, prolonged. Fig. 151. The velocity of a projectile diminishes from the time it leaves its piece, while the velocity generated by the rupturing force remains constant. It follows, therefore, that the dispersion of a spherical case-shot increases with the distance, while the force of impact is diminished. The distance at which a spherical case-shot ceases to be effective depends on the relation between the remaining velocity and the velocity generated by the force of rupture. The improvements which have lately been introduced into this species of projectile, have for their objects, to increase the remaining velocity at any point by increasing the propelling charge, and to diminish the force of rupture, and at the same time increase the number of contained projectiles by diminishing the bursting-charge. By filling the interstices of the bullets with sulphur or rosin, the propelling charge of a spherical case-shot can be made the same as that of a solid shot. (See chapter II.) It is considered that a spherical case-shot is effective when a large portion of the projectiles have sufficient SHRAPNEL FIRING. - 467 force to penetrate one inch of soft pine. The present 12-pdr. spherical case-shot, fired with a charge of 2pounds of powder, has a remaining velocity of about 500 feet at a distance of 1,500 yards, which renders it effective at this distance. The principal difficulty experienced in firing a spherical case-shot is, to burst it at the proper distance in front of the object. This arises from the difficulty of estimating the correct distance of the object, the rapid flight of the projectile, and the difficulty of observing the effect of a shot in order that correction may be made for the succeeding one, if necessary. To overcome these difficulties requires skill and judgment on the part of the gunner, and great accuracy and delicacy in the operation of the fuze. The proper position of the point of rupture varies from 50 to 130 yards in front of, and from 15 to 20 feet above, the object. The mean number of destructive pieces from a 12-pdr. spherical case-shot, which may strike a target 9 feet high and 54 feet long, situated at a distance of 800 yards, -is 30. The effect of elongated case-shot from rifle-cannon is said to extend upward of 2,000 yards. This arises from the fact that an oblong projectile preserves its velocity for a much longer distance than a round one. The weight of a spherical case-shot is about the same as a solid shot of the same size, and being fired with the same charge of powder, it can be used for attaining long ranges, in the absence of solid shot. For this purpose the fuze should not be cut. Spherical case-shot should not be used for a less dis 468 DIFFERENT KINDS OF FIRES. tance than 500 yards; although in cases of emergency the fuze may be cut so short that the projectile will burst at the muzzle of the piece, in which case it will act like grape or canister shot. 458. Grape and canister firing. In grape and canister firing, the apex of the cone of dispersion is situated in the muzzle of the piece, and the destructive effect is confined to short distances. The shape of this cone is the same as in spherical case-shot; its intersection by a vertical plane is circular, while that of a horizontal plane, as the ground, is an oval, with its greatest diameter in the plane of fire. The greatest number of projectiles are found around the axis of the cone, while the extreme deviations amount to nearly one-tenth of the range. The most suitable distance for field canister-shot is from 350 to 500 yards; if the ground be hard and the surface be uniform, the effect may extend as far as 800 yards. In cases of great emergency a double charge of canister, fired with a single cartridge, may be used for distances between 150 and 200 yards. Under favorable circumstances, one-third of the whole number of contained projectiles will strike the size of a half-battalion-front of infantry, and one-half, the front of a squadron of cavalry. Grape and canister shot are employed in siege and sea-coast operations; in the latter, they are effective against boats, and the rigging, &c., of vessels. Grapeshot, being larger than canister-shot, are effective at greater distances. Canister-shot for the mountain service are not effective beyond 250 and 300 yards. SMALL-ARM FIRING. 469 459. Small-arm firing. Beyond 200 yards, the fire of the smooth-bored musket becomes very uncertain against individual objects, as the lateral deviations often exceed four feet; but by aiming high it may be made effective against troops in mass at 400 yards. The fire of the rifle-musket is effective at 1,000 yards; the angle of fall, however, is so great (about 50) that great care must be exercised in determining the exact distance of the object. If the ground be favorable, the projectile will ricochet at 1,000 yards, which increases the dangerous space, and therefore the chances of hitting the object. The limit of any fire is determined by the distinctness of vision;-the limit of distinct vision for a foot-soldier is about 1,100 yards; that for a mounted soldier is about 1,300 yards. The effect of small-arm firing depends much on the skill and self-possession of the soldier in action; for, without these qualities, the most powerful and accurate arms will be of little avail. The number of cartridges expended for each person disabled in previous European wars has been variously stated to be from 3,000 to 10,000. In the late Mexican war, where an unusually large proportion of the American troops were armed with rifles, this number has been estimated to be from 300 to 400. Where a soldier discharges his piece from the back of a horse, as in the cavalry service, the effect of fire is much less than in the dragoon and mounted-rifle services, where he rides from point to point, but discharges his piece on foot. At short distances, and against troops in mass, two or three round bullets may be employed with effect; 470 DIFFERENT KINDS OF FIRES. the bullets should be so small that they will readily drop to their place without the aid of the ramrod. Buckshot have very little effect beyond 100 yards. The following are the mean deviations of the riflemusket fired from a shoulder and rest. DISTANCE. VERTICAL. HORIZONTAL. Yards. Inches. Inches. 100 1.9 1.5 600 22.2 14.6 1000 55.9 25.5 EFFECT ON CAST-IRON. 471 CHAPTER XI. EFFECTS OF PROJECTILES. 460. General considerations. A knowledge of the destructive effects of projectiles on iron, wood, earth, and masonry, the materials of which covering masses are made, is of very great importance in a military point of view. In general, these effects, and particularly that of penetration, depend on the nature of the projectile, its initial velocity, and the distance of the object. 461. Cast-iron. Experiment shows that cast-iron, even in large masses, is easily broken by projectiles; it should not, therefore, be used for gun-carriages, nor the revetment of fortifications. 462. Wrought-iron. The following deductions have been made firom trials with armor plates, extending over several years. ist. The best material to resist projectiles is soft, tough. wrought-iron; and to attain these qualities it should be pure — free from sulphur, phosphorus and carbon. Steely iron, commonly known as homogeneous iron, puddled steel, etc., when in large masses, is easily cracked by shot, and is not, therefore, suitable for armor plates. Thin plates afford a greater comparative resistance. Soft steel may be used for armor plates; but when cost is taken into consideration, it is doubtful if it possesses any advantages over wroughtilron. 2d. Rolled iron does not offer quite so much resist 472 EFFECTS OF PROJECTILES. ance as hammered iron, yet if the size of the plate admit of it, it is to be preferred on the score of economy. Plates should be as large as possible to reduce the number of joints, which are lines of weakness. 3d. A solid plate offers, for the same thickness, a greater resistance to a projectile than a laminated one, or one made up of several thinner plates; but when the surface is rounded in shape and of small extent, as in the Monitor turrets, the latter may be used to great advantage, as great thickness of metal may thereby be easily obtained. 4th. The resistance of a plate to perforation is very much increased by a suitable backing. Cast-iron, granite, and brick in masses, while they enable a plate to offer a very great resistance, are soon broken up by the blows of heavy projectiles, and their fragments thrown off with great force. Oak and teak are the most suitable timbers for backing plates, and are used as such on vessels. A yielding backing is found to occasion less strain on the fastenings than a very hard one. 5th. Where projectiles are made of the same material and are similar in shape, their penetration into unbacked plates is nearly in proportion to their living force, or their weight multiplied by the square of the'velocity of impact. The resistance which an unbacked plate offers to penetration is nearly in proportion to the square of its thickness, provided this thickness be confined within ordinary limits. In the case of oblique plates the penetration diminishes nearly with the sine of the angle of incidence. 6th. The most suitable material for shells to be used against iron plates is tempered steel. These projectiles ARMOR PLATES. 473 should be made of cylindrical shape, with thick sides and bottom, to direct the explosive effect of the charge forward after penetration is effected (see figs. 163, 164). The most suitable material for solid shot is hard and tough cast-iron. Captain Pallisers' chilled shot are made of this material, and so are the shot made by the Army and Navy Ord. Departments of this country. Round shells made of cast-iron will be broken' in passing through an inch plate, and an ordinary cast-iron shot will be broken in passing through a two inch plate. Late experience shows that the pointed, or ogeeval, is better than the flat form of head for penetration of iron plates. 7th. It follows from the'preceding that the most suitable covering or shield for cannon, is a conical-shaped turret made of wrought-iron plates, as large as it is practicable to make them, backed with oak or teak. To protect the gunners from the fragments of projectiles which may penetrate completely through this covering, there should be an "inner skin" of thick boiler plate placed behind the wood. The Chief of the Naval Ordnance Bureau, in a late annual report uses the following language, viz.:-"As "a general summary of the results obtained in practice "against iron targets, it may be stated that the XI-inch "gun is capable of piercing 4~ inches of the best iron "plating, backed by 20 inches of solid oak. The new "X-inch solid shot gun will penetrate any iron-clad of "which we have, at present, any information. And in "the target,experiments, the XV-inch gun has broken "up and shattered plates exceeding in thickness any. "thing hitherto proposed as defensive armor." He also states, "that cast-iron projectiles made of the 474 EFFECTS OF PROJECTILES. " best charcoal iron, poured and worked in a peculiar "manner so as to obtain hard and solid masses, have "been found by recent experiment able to penetrate at "close range any given thickness of iron armor which "can be worn on the sides of ships of war. In fact, the " penetration is quite as great and uniform as that ob"tained, with steel shot of equal weights propelled by "similar charges, the only difference being that the iron " breaks after passing through, while the steel is only " compressed or flattened,-a result rather in favor of " the iron shot if entrance is made between decks, where m" en are exposed to its fragments." They may also be cast in strings on Gen. Rodman's plan, see page 89. 463. Effect on wood. The effect of a projectile fired against wood varies with the nature of the wood and the direction of the penetration. If the projectile strike perpendicular to the fibres, and the fibres be tough and elastic, as in the case of oak, a portion of them are crushed, and others are bent under the pressure of the projectile, but regain their form as soon as it has passed by them. It is found that a hole, formed in oak by a ball 4 inches in diameter, closes up again, so as to leave an opening scarcely large enough to measure the depth of penetration. The size of the hole and the shattering effect increases rapidly for the larger calibres. A 9-inch projectile has been found to leave a hole that does not close up, and to tear away large fragments from the back portion of an oak target representing the side of a ship of war, the effect of which, on a vessel, would have been to injure the crew stationed around, or, if the hole had been situated at EFFECT ON' EARTH. 4 7 5 or below the water line, to have endangered the vessel. If penetration take place in the direction of the fibres, the piece is almost always split, even by the smallest shot, and splinters are thrown to a considerable distance. In consequence of the softness of white pine, nearly all the fibres struck are broken, and the orifice is nearly the size of the projectile; for the same reason, the effects of the projectile do not extend much beyond the orifice; pine is therefore to be preferred to oak for structures that are not intended to resist cannon projectiles, as block-houses, etc. 464. Effect on earth. Earth possesses advantages over all other materials as a covering against projectiles; it is cheap and easily obtained, it offers considerable resistance to penetration, and to a certain extent regains its position after displacement. It is found by experience that a projectile has very little effect on an earthen parapet unless it passes completely through it, and that injury done by day can be promptly repaired at night. Wherever masonry is liable to be breached, it should be masked by earth works with natural slopes. General Gillmore states, as the result of his experience before Charleston, that the powers of resistance of pure, compact, quartz sand to the penetration of projectiles, very much exceeds that of ordinary earth, or mixture of several earths. The size of the openings formed by the passage of a projectile into earth is about one-third larger than the projectile, increasing however towards the outer orifice. Rifle-projectiles are easily deflected from their course in earth. They are sometimes found lying in a position at right angles to their course, and sometimes with the 476 EFFECTS OF PROJECTILES. base to the front; hence their penetration is variable. Unless a shell be very large in proportion to the mass of earth penetrated, its explosion will produce but little displacement,-generally a small opening is formed around an exploded shell by the action of the gas in pressing back the earth. Experience at Fort Wagner showed that it took one pound of metal to permanently displace 3.27 lbs. of the sand of which the Fort was made. Time fuzes, being liable to be extinguished by the pressure of the earth, are inferior to percussion fuzes, which produce explosion when the projectile has made about three-fourths of its proper penetration. The penetration in earth of oblong, comparled to round projectiles, when fired with service charges, and at a distance of about 400 yds., is at least one-fourtth greater. This difference, however, is less at short and greater at long distances. The penetration of the smallest, or 3-in. cannon projectile, at a distance of 400 yds., in a newly made parapet of loam mixed with gravel, is about 6 feet. The 100-pdr. projectile, under similar circumstances, pene-.trates about 16 feet. A penetration as great as 31~ ft. has been obtained at the Washington Navy Yard by firing a 12-in. rifle-projectile into a natural clay bank, at a short distance. The greatest penetration of a 15-in. solid shot, fired with 50 lbs. of pQowder, in well rammed sand, at a distance of 400 yds., is 20 ft. 465. Penetration. The resistance which a projectile encounters in penetration, arises from, the cohesion and inertia of the particles, and the friction of the particles against the surface of the projectile. PENETRATION. 477 To obtain an expression for the penetration, we will suppose that the resistance is proportional to the area of the cross-section of the projectile, and independent of the velocity. Let E be the penetration expressed in calibres, D the density of the projectile, v its velocity at the commencement of penetration, r the radius of the projectile, and R the constant resistance experienced by a unit of surface; the quantity of work done in overcoming the resistance is, rr2. E. 2r. BR; and the living force of the projectile is 4 Dr8 DV 3 g But the living force is equal to twice the quantity of work; hence we have, 4TrrRJEJ 4J#rr-D V2; 3 g by making K= ER we obtain, E= Kv2D. Take another projectile, having a velocity v', a den. sity dl, and a penetration e, and we have the expression, e= ITv12d. Dividing the preceding expression by this, member by member, and we have, E=e v2d; that is to say, the penetrations of,similar p9rojectiles into a given substance, are proportional to the squares of the velocities of impact, and to the diameters* and den-sities of the prajectiles. * The diameters of all service projectiles are given in the Ordnance Manual. 478. EFFECTS OF PROJECTILES. Knowing, therefore, the penetration e, for a given velocity and projectile, we can obtain the penetration E, for another projectile and velocity. Let e represent the penetration for a shot moving with a velocity of 1,650 feet, the expression becomes, v2 _D 16502 d This formula has been found by experience to give, with sufficient accuracy, the penetration of projectiles in hard substances, as wood, cast-iron, and masonry, for all velocities up to 1,000 feet per second. The following penetrations, or values of e, have been found for round shot moving with a velocity of 1,650 feet, viz.: Cast-iron (depending on its nature),.5 to Lead,..... 3 to 3' Calcareous rocks (particular kind), 2 Masonry of good quality,.. 4 4" rubble,... 5 to 5" brick,.... 8 Substituting the above values of e in the value of ],.we obtain the penetrations, expressed in terms of the diameter of the projectile, for any velocity not exceeding 1,000 feet. Solid shot are broken, when fired against very hard substances, with charges exceeding the following, viz.: Against cast-iron,. T 1 lead,.... ".calcareous rock (oolitic),. T masonry,.. 3 * Some shot resist these charges. PENETRATION. 479 The velocity v, is the velocity which the projectile possesses at the commencement of penetration; if the piece be situated at a distance, it is necessary to determine the remaining velocity, by making allowance for the resistance of the air. Equation (20), page 408. V?2 P Wood The formula E=e -- D may be used to 1050~ d calculate penetrations in wood, for velocities which do not exceed 1,000 feet, making use of the following values of e for penetrations perpendicular to the fibre: For oak of ordinary quality,.. e 12" elm,...... 16 " pine,...23 For velocities exceeding 1,000 feet, the formula just employed gives results which are too large; from this it is inferred that penetration really increases less rapidly than the square of the velocity. Earth. In the experiments made at Metz, in 1834, on various kinds of earths, it was found necessary to modify this expression for penetration. Calling p the weight of the powder, and m the weight of the projectile, the expression becomes, for all charges between - and 214, log.(1+480 X log.(l+480-) -e ~log. (1+4 80 X 1) 2.20683 d The following values of e, for a charge of -, were found for different earths: For sand mixed with gravel, e —1034 For earth, settled,.. 172 480 EFFECTS OF PROJECTILES. Potter's clay, saturated with water, 36 Light earth newly dug over,. 32 The penetration being given in terms of the weight of the powder and projectile, the piece should be sufficiently long to obtain the full force of the charge, or from 17 to 20 calibres; or, in other words, the expression is only suited to field and siege guns. In general, sand, sandy earth mixed with gravel, small stones, chalk, or tufa, resist shot better than the productive earths, or clay, or earth that retains moisture. Water. To obtain penetration in water, replace 480P by 4800P —, and make e equal to 275 calibres. In some late experiments, it was found that the Whitworth projectile had sufficient force, at short distances. to pass through 33 feet of water and then penetrate 12 or 14 inches of oak beams or scantling. The penetration of a rifle-projectile in water, depends much on the direction of its axis with respect to penetration, for instance, penetration rapidly diminishes at long distances, as the axis of the projectile strikes the surface of the water under a diminished angle. 466. Effect on masonry. The effect of a projectile against masonry, is to form a truncated conical hole, terminated by another of a II ~ ~cylindrical form. (See fig. 153.) The material in front of and around the projecFig. 153. tile is broken and shattered, and the end of the cylindrical hole even reduced to powder. Pieces of the masonry are sometimes thrown BREACHING. 481 50 or 60 yards from the wall. The elasticity developed by the shock, reacts upon the projectile, sometimes throwing it back 150 yards, so as to be dangerous to persons in a breaching battery. The exterior opening varies from 4 to 5 times the diameter of the projectile, and the depth, as we have seen, varies with the size and density of the projectile, and its velocity. With charges of -, L,, and ~, a projectile ceases to rebound from a wall of masonry when the angles, formed by the line of fire and the surface of the wall, exceed 20~, 240~, 33~, 43~, respectively. With these angles, the angle of reflection is much greater than the angle of incidence, and the velocity after impact is very slight. When a projectile strikes against a surface of oak, as the side of a ship, it will not stick if the angle of incidence be less than 15~, and if it do not penetrate to a depth nearly equal to its diameter. Solid cast-iron shot break against granite, but not against freestone or brick. Shells are broken into small fragments against each of these materials. 467. Breaching. Escalade being ordinarily very difficult, particularly when the besieged are aware of the intention of the besiegers, the latter are generally conimpelled to destroy a portion of the face of the work to obtain an entrance. Such an opening is called a breach; and to effect it with artillery, particularly in a wellconstructed work, where no part of the scarp-wall is visible from the adjacent ground, within effective range of siege-cannon, breaching-6aftterie8 are established either on the crest of the covered way, or on the glacis. When the walls of fortified places were very high and not supported by terraces or ramparts, stone pro31 482 EFFECTS OF PROJECTILES. jectiles were used. From the want of sufficient hardness in these projectiles, the besiegers were forced to commence battering at the top of the wall where the least resistance was offered, and gradually to lower the shot until the breach reached the wrecks already formed at the base of the wall. When the style of fortification was changed, this operation became very laborious, the ascent was very steep, and the breach was often impracticable. This method was abandoned and mining substituted. Iron projectiles superseded stone, and then a more rapid mode of effecting a practicable breach was suggested and confirmed by experience. Vauban recommended increasing the size of the hole first formed, by continually firing at its sides until the wall should fall; but the ball was found to glance into it, and injure but slightly the untouched portion of the revetment. The best mode, however, as found by experiment, is to cut the wall up into detached parts, by making one horizontal and several vertical fissures, and battering each part down separately. (Fig. 154.) The easiest mode of making the cut is to direct the shots -upon the same line, and form a series of holes (fig. 154), a Fig. 154. little greater than a diameter apart, and then to fire a second series of shots, directed at the intervals between the first, and so on, until an opening is made completely through the wall. The first cut is made horizontally, and finished, which will be known by the earth falling through it; the vertical cuts are then made, there being one at each end of the intended breach. These cuts are commenced at the BREACHING.'4&3 horizontal cut, and raised until the wall, isolated from its supports, sinks, overturns, and breaks into pieces, which become covered by falling earth. If the earth be sustained by its tenacity, loaded shells are fired into it, which, acting like small mines, cause it to fall, and make the breach practicable, or of easy ascent. If the portion of the wall between the vertical cuts should not be overthrown by the pressure of the earth behind, it must be detached by a few volleys of solid shot, fired at its centre. This will speedily bring it down in a mass. The moment the wall is down, and the parapet destroyed, the breach will be as perfect, and the slope as easy of ascent, as it can be made by the fire of the batteries. It is important to determine the height of the horizontal cut above the bottom of the ditch, for, if this height be not properly chosen, the breach may be -difficult, if not impracticable. If too high, the ramp composed of the debris will be intercepted by a portion of the wall; if too low, the opening will be masked by the debris, and the formation of the cut impeded. The most suitable height is nearly equal to the thickness of the wall where the cut is established. The thickness, where not known, can be deduced from the dimensions necessary to be given to the wall, to resist the pressure of the earth of the rampart and parapet. The time necessary to make a breach, depends on the size of the breach to be made, the material of the scarp, the number of guns, &c. For a breach of 20 to 30 yards in length, at forty yards from the battery, 1,500 shot of large calibre will be required; but when the battery is at a greater distance, a greater number of 484 EFFECTS OF PROJECTILES. projectiles will be necessary, on account of the diminished accuracy and penetration. Thus, at 500 or 600 yards 9,000 to 10,000 may be needed. Rules. The following general rules should be observed in firing to effect a breach1. Ascertain as accurately as possible the widths of the ditch and covered way, the height of the scarpwall, the thickness of the parapet, the height of the counterscarp, and crest of the covered way. By the aid. of a profile that can be constructed from this data, determine the height of the horizontal cut to be made in the scarp, so that the slope of the ramp shall be 45~. This height should never be below a fourth of that of the scarp, and, to avoid interference from the wrecks, it should be nearly equal to the presumed thickness of the wall at the cut. If the ditch be a wet one, commence cutting at the water's edge. 2. From the number of pieces with which the battery its to be armed, and the length of the breach, determine the field of fire of each piece, and the length of cut that it is to make. 3. Ascertain the angle of elevation, or depression, for each piece, to strike the cut, and mark it unalterably on the elevating screw. 4. Direct each piece on the right or left of the part to be cut, and space the shot from right to left, or from left to right, at 1 to 1~ yards for the 24-pdr., and 1 yard for the 18-pdr. Mark on the platform the direction of the stock and wheels at each shot. Returning then from left to right, or from right to left, fire at the middle of the intervals left by the first shot, and mark the directions as before. Continue this firing BREACHING WITH RIFLE-CANNON. 485 regularly at the most prominent points, and make the cut progress equally throughout. 5. Fire at the horizontal cut until the earth falls throughout the cut. 6. Determine the number of vertical cuts to be made, at the rate, at most, of one to a piece, without spacing more than 10 yards apart, in order that no part shall be sustained by more than one counterfort. Fire as in the case of the horizontal cut, commencing at the upper line. 7. See that the extreme vertical cuts progress as rapidly as the interior ones, and direct the adjoining guns upon them if necessary. 8. If the wall do not fall after the cuts are made, fire a few volleys at the middle of the spaces thus outlined. 9. After the fall of the wall, break down the counterforts, and, if time or resources permit, replace the guns by 8-inch howitzers, and fire upon the earth with loaded shells, or fire shells from the guns. 468. Breaching with rifle-cannon. The foregoing section has reference particularly to breaching masonry with smooth-bored guns. The principles and, to a certain extent, the rules laid down, are applicable to rifled guns, the only difference being that, fiom their superior penetration and accuracy, the latter are effective at much longer distances. This has been fully shown by trials in England and actual experience in this country. The subjects of experiment in England were two Martello towers, 30 feet high and 48 feet diameter; the walls were firom 7~ to 10 feet thick of solid brick masonry of good quality. The distance was 1,032 yds., — 486 EFFECTS OF PROJECTILES. more than twenty times the usual breaching distance. The pieces were Armstrong guns, throwing projectiles weighing 40, 80 and 100 lbs., and the 32-pdr. and 68-pdr. smooth bored guns. The 80-pdr. shot passed completely through the masonry (7i feet), and the 40-pdr. percussion shells lodged in the brick work at a depth of 5 feet. After firing 170 projectiles, a small portion of which were loaded shells, the entire land side of the tower was thrown down, and the interior space was filled with the debris of the vaulted roof, forming a pile, which alone saved the opposite side from destruction. The average depth of penetration of the smooth bored guns was 1.91 feet, and was produced by 163 projectiles. It was found that the penetration of the 80-pdr. solid shot with 10 lbs. of powder in this brick masonry was 7~ feet, while that of the 68-pdr., with 16 lbs. of powder, was only 13 feet. Fort Pulaski, a casemate work made of brick masonrly of good quality, and having walls 73 feet thick, was breached by batteries situated at distances varying from 16i50 to 1740 yds. The pieces employed were three 10-inch and one 8-inch columbiads, five 30-pdr. Parrott and one 24-pdr., two 32-pdr. and two 42-pdr. sea-coast guns rifled on the James plan. There were several 10 and 13-inch sea-coast mortars, and 8 and 10-inch columlbiads placed further off, or at distances varying fiom 2400 to 3400 yds.; but these pieces, and especially the mortars, produced but little effect, owing to the small size of the Fort and the inaccuracy of their fire. Less than owetenth of the mortar shells fell inside of the Fort, and no shell penetrated through the casemate roofs. EFFECT OF BULLETS. 487 Subsequently, Fort Sumter, a work similar to the foregoing in its construction, was breached at distances varying fiom 3428 to 4290 yds. by nine 100-pdrs., five 200-pdrs., and one 300-pdr. Parrott rifle-guns. Against Fort Pulaski 110,643 lbs. of metal were fired at the breach, 58 per cent. of which was from the rifle-guns. Against Fort Sumter there were fired 552,683 lbs. of metal, about one-half of which reached the Fort to foria the breech. The most destructive prlojectile against masonry is the elongated percussion shell. 469. Effect of bullets. The penetration of the new breach-loading rifle-musket bullet, in a target made of pine boards, one inch thick, is as follows: At 100 yds., 13 inches; at 500 yds., 9 inches. If bullets are hardened }by the addition of a little tin or antimony to the lead, their penetration is very much increased. From experiments made in Denmark, the following lrelations were found between the penetration of a bullet in pine and its effects on the body of a living horse, viz.: Ist, When the force of the bullet is sufficient to penetrate.31 inch into pine, it is only sufficient to produce a'slight contusion of the skin; 2d, When the force of penetration is equal to 0.63 inch, the wound begins to be dangerous, but does not disable; 3d, When the force of penetration is equal to 1.2 inch, the wound is very dangerous. A plate of wrought-iron three-sixteenths of an inch thick, is sufficient to resist a rifle-musket bullet at distances varying fiom 20 to 200 yds. That a rope mantlet may give full protection against rifle-musket bullets, it should be composed of five layers (three vertical and two horizontal), of four and a half inch rope. 488 EMPLOYMENT OF FIELD-ARTILLERY. CHAPTER XII. EMPLOYMIENT OF FIELD-ARTILLERY.* 470. Greatest range. The extreme range of field-artillery has been stated to be about 3,000 yards;t a somewhat greater range than this can be obtained by sinking the trail of the carriage into the ground, thereby increasing the elevation of the piece; but in consequence of the great strain thus thrown upon the carriage, and the great inaccuracy of the fire, it should be seldom resorted to, unless it be to produce a moral effect on an armiy in retreat, or passing a defile. If employed against an enemy acting on the offensive, it would have the effect, from its extreme inaccuracy, to give him increased confidence. In general terms, firing at long range should only be employed when the nature of the ground, or the shortness of the time, does not permit a nearer approach to the object; and it should always cease when the object of the fire is attained. Effective range. The greatest effective range of fieldartillery varies from 1,400 to 1,800 yards. Batteries of position belonging to an army acting on the defensive, should open fire at a distance of 1,300 or 1,400 yards. The object of this fire is not so much to arrest, as to retard, the movement of the enemy, and compel him to establish batteries to cover his approach. The distances * Vide Decker's.Instruction Pratique, &c. { The ranges in this chapter refer to smooth-bored rather than rifled guns. The principles, however, involved in it, are equally applicable to both. GREATEST RANGE. 489 should be carefully estimated, and the firing should take place slowly, in order that the effect of each shot may be observed, and the aim 6orrected, if necessary. Rapid.and continuous firing should commence at a distance of 800 or 1,000 yards; the attacking party should, at the same time, establish his batteries to cover the deployment of his columns, and to enable him to make the necessary preparations for attack. At a distance of 600 or 700 yards, or point-blank distance, the-fire becomes very destructive; generally not more than six or eight shots can be fired before one of the. parties will either advance or retire. As the distance closes, canister-shot should replace round-shot, which generally ends in producing disorder. Against infantry. Formerly artillery could take up a position about 300 or 400 yards in front of infantry without serious loss; but the introduction of the riflemusket has produced a very great change in the relative powers of these two arms. The experiments made at the musketry-school at Hythe, show conclusively that artillery cannot long maintain a position within half a mile of' properly instructed skirmishers, as the fire of rifle-musketry at this distance is as effective as that of canister at 250 or 300 yards. Should the surface of the ground be broken, or of such nature as to afford shelter to skirmishers, the preponderance will be still more in their favor. And should the artillery not succeed in silencing the fire of the skirmishers by well served case-shot, it will be obliged to retire beyond the reach of the rifles, and trust to the effect of round and spherical case-shot upon the enemy's masses. 490 EMPLOYXMENT OF FIELD-ARTILLERY. -Agiaineyt cavalry. Cavalry, in charging upon an enemy situated at a distance of 1,000 yards, pass over the intervening space in about seven minutes. Each piece may fire nine rounds of solid shot, or spherical case-shot, in the first 400 yards, two solid and three canister shot in the next 400 yards, and two rounds of canister-shot while passing over the remaining 200 yards, making a total of eleven round and five canister shot. Neither spherical case-shot nor shells should be fired against cavalry in rapid motion; and care should be taken not to cease firing solid shot too soon in order to commence firing canister. 471. Employment of different kinds of fire. The following circumstances should be known, to enable the artillerist to select the most suitable fire for a particular occasion: 1st. The distance of the enemy. 2d,. The conformation and quality of the intervening ground. 3d. The formation of the enemy, as far as can be seen or judged of. Direct fire. Direct fire should be employed wherever the surface of the ground is uneven and the quality of 4he soil varied, or wherever a portion fired over is smooth and the remainder broken, or the soil soft and light. There are other special cases where direct fire should be employed: 1st. When the enemy is so situated as to conceal the depth of his formation; otherwise the ground in rear: of his front line may be such that the ricochet will not take effect; 2d. When the enemy is about to pass a defile, and the head of the column only is seen; or when the depth of the column can be seen, by being commanded EMPLOYMENT OF DIFFERENT KINDS OF FIRE. 491 or overlooked; in this case, the projectile which would miss the head might strike the middle or the rear of the column; 3d. It should be employed in all sustained cannonacdes, because the effect of its shots can be more easily distinguished than that produced by the shots of a rolling fire. The aini should be corrected by observing the point of fall of the projectile; and, for this purpose, it is desirable to take the mean of three shots. If a rolling fire be employed under these circumstances, the character of the ground and formation of the enemy may be such, that the cannonade may be carried on for hours without knowingf what effect is produced. To produce good results with direct fire, it is absolutely necessary to ascertain the exact distance of the enemy, which can only be done by a practised eye. This circumstance will be appreciated when we consider that, if a shot only strike the ground fifteen yards in front of a target six feet high, it will pass completely over it. When the object is not on the same level with the piece, tlie character of the fire will be determined by the nature of the intervening ground. If the surface be uniform, and have an inclination to -the horizon not exceeding 15~, above or below, no change need be made in the kind of fire, or elevation of the piece, from what they would be on horizontal ground. If the enemy be posted on a mountain, or in a valley, the direct fire can only be used. As it is often difficult to estimate the distance, the pieces should be aimed with great precision, and the point of fall should be 492 EM3PLOYMENT OF FIELD-ARTILLERY. carefully noted; the firing should be deliberate, and it should be recollected that a different height of sight is necessary than when the object is on level ground. 472. Ricochet fire. Ricochet fire should never be used for a less distance-than 1,000 yards, even when the ground is favorable; for, in order that this fire may produce its greatest effect, it is necessary that the projectile should make two or three rebounds in firont of the enemy, which it rarely does at a less distance than 1,000 or 1,100 yards. If the ground, for 300 or 400 yards in front of the pieces, be soft and uneven, or if it be soft and uneven for 100 or 300 yards in front of the enemy, rolling fire, which is a species of ricochet fire, cannot be employed with effect. Large and deep objects, as a mass of troops, a park, or a.column of artillery on the march, are the most suitable objects for ricochet fire, as these objects present several lines, one behind the other. 473. Canister fire. The fire of canister does not always produce the effect anticipated for it, for the following reasons, viz.: 1st. The object is thought to be nearer than it really is, and the firing sometimes commences too soon. 2d. The danger is often thought to be more imminent than it really is, and, consequently, proper care is not observed in aiming. 3d. The character of the ground- is not properly appreciated; and too much confidence is reposed in the effect of the projectiles thrown over unfavorable ground. 474. Field-howitzers. The extreme range of shells fired from field-howitzers has been stated to be firom 2,500 to 3,000 yards. The deviation of shells at ex LONG RANGES.:493 treme distances is so great that they should only be employed against large objects, as cities, camps, &c. The greatest effective range of howitzer-shells is about 1,500 yards; shells should only be employed at this distance in the offence, and then, rather as an exception to the general rule. The gun should always be employed when capable of producing the same effect as the howitzer. Shells act by percussion, by explosion, and by moral effect; and they should be employed in preference to shot under the following circumstances, viz.: 1st. When the enemy-is stationary and under cover. 2d. When the ground is much broken, or cannot be seen. 3d. When troops are posted in woods. 4th. From one mountain to another. -5th. When the enemy is posted on higher or lower ground. 6th. When on a road leading through a valley. 7th. For incendiary purposes. 8th. In pursuit. 9th.: Whenever it is necessary to produce a moral rather than a physical effect. EMPLOYMENT OF SIEGE-CANNON. In siege operations, the same fires are employed as in the field, but under different circumstances. The position of the object is generally fixed and known, and there is sufficient time to consider the best means of attaining it. 4'75. Long ranges. The greatest range of the 24-pdr. 494 EMPLOYMENT OF FIELD-ARTILLERY. siege-gun, mounted on its appropriate carriage, is about 3,500 yards; but the defence should not, without good reason, make use of a greater distance than 950 yards, or point-blank distance, for it is his duty to economize his ammunition, if it cannot be replaced. It will be proper to fire at a reconnoitring party at a distance of 1,000 or 1,100 yards, to prevent a nearer approach, and against strong attacking columns, provided they offer sufficient surface to render the chances of hitting probable. In the attack. Firing at long ranges, on the part of the besiegers, should be strictly forbidden, as it would disclose to the enemy the proposed front of attack, without any compensating advantage. In the siege service, it is more important to avoid useless firing than in the field, for every shot that does not contribute to the progress of the attack, by weakening the defence, is a shot lost. 476. Enfilading and counter fires. An enilcadingy fire is directed along a particular portion of a work, and a counter fire is directed toward it. hIn t#he defence. Solid shot are used in enfilading and counter fires under the following circumstances: 1st. To destroy the head of a sap, or the parapet of a trench. 2d. When the enemy passes from the first to the second parallel, and before he has completed the b atteries intended to dismount the artillery of the garrison. 3d. To batter vigorously the lateral works of attack as soon as they are finished. 4th. To protect and support sorties. The guns placed on the parapet of the place keep up a warm fire of ENFILADING AND COUNTER FIRES. 495 solid shot against the batteries of attack, and the Iheads of saps, until they are masked by the troops making the sortie. 5th. To prevent the enemy from following too closely upon the heels of the party, which, having made the sortie, are returning, successful or otherwise. 6th. From the guns placed on the flanks of the bastions when the besiegers attempt to pass the ditch; in this case the fire is plunging. 7th. To drive the besiegers from any outwork that they may have taken. 8th. In a cannonade, the object of which is to dismount the besiegers' guns. In the attack. The oblject of enfilading fire in the attack of a place, is to rake the terrepleins of the faces, curtains, &c., and to render them untenable; for this purpose the batteries should be established on the prolongation of, and at right angles, or nearly so, with the direction of the part to be enfiladed. As the portion of the works to be attained is not commanded by the besiegers' cannon, enfilading fire, under these circumstaaces, becomes ricochet fire, the nature and treatment of which have already been described. Enfilading and counter batteries are generally established at 300 or 600 yards from the place, or at the first and second parallels. As the object of a counter battery is to silence the fire of the place by dismounting the guns, its pieces should be directed against the embrasures. This demands great care in aiming, and great accuracy of fire; the heaviest smooth-bored or rifled guns should therefore be employed for this purpose. 496 EMPLOYMENT OF FIELD-ARTILLERY. 477. Firing in breach, When the besiegers have approached to a suitable distance to commence the breach, the opposing artillery will have been silenced; but they will be subjected to flank and rear fires, against which they will protect themselves by traverses. Counter-batteries will also be established with the breaching-batteries, the object of which will be to silence the artillery bearing on the breaching-batteries, and the passage of the ditch. The method of forming a breach has already been described. 478. Fire of ease-shot. Case-shot should be employed in the defence of a work under the following circumstances, viz.: 1st. In sorties, where field-artillery can be employed. 2d. At all points liable to sudden attacks, as on avenues leading toward gates, or on bridges. Pieces situated on the flanks are particularly suited to this fire. 3d. Against the gorge of an outwork which the enemy may make a bold attempt to seize. For this purpose, pieces on the curtains, or shoulder angles, should be employed, taking care, at the same time, not to fire over works occupied by the defence. 4th. This fire may be safely employed in the defence of dry ditches, reveted with masonry. 5th. Against the batteries of the first parallel during their erection, and after their position has been disclosed by means of fire-balls. 6th. Against the head of a sap at night. 7th. Against the workmen engaged on the construction of the second parallel. 8th. Against the workmen engaged on the third par FIRE OF THE SIEGE-HOWITZER. 497 allel, against the works leading to the covered way, and against the crowning of the covered way. 9th. Against craters formed by the explosion of mines, to prevent the enemy from crowning them. 10th. Against the passage of the ditch. 11th. Against the breach. 12th. All cannon on the flanks which remain mounted, fire rapidly grape or canister shot at the moment of assault. In the attack. The besiegers are much more restricted in the use of case-shot than the besieged. It should be principally employed under the following circumstances, viz.: 1st. By cannon placed on the flanks of attack whenever the besieged make a sortie, and come within suitable range. 2d. At night, against the embrasures which have been cannonaded during the day with solid shot, to prevent them from being repaired. 3d. Against the flanks, during the night. 4th. Against the breach during the day or night, as soon xas completed, to prevent the enemy from erecting means for defending it. 5th. Against the besieged, if he attempt to pass out through the breach, after the assault has been repelled. 479. Fire of the siege-howitzer. The siege.howitzer should be employed in the defence,1st. Against an attacking column, when the ground in front of the place affords a shelter against the fire of guns. 2d. Against the works of the besiegers. Howitzers 32 498 EEMPLOYMENT OF FIELD-ARTILLERY. are placed on the salients to blow up, with shells, the works situated on the prolongations of the capitals. 3d. Against the batteries in process of construction on the three parallels. 4th. Against the heads of saps; this fire should be executed with small charges. 5th. The counter approaches are armed with howitzers. 6th. Against troops opposing sorties, and especially against cavalry. 7th. Against the enemy's dep6ts, when their position is known, and when they are within effective range. 8th. Against the enemy's convoys, when they can be reached, and they offer sufficient surface. In the attack. Howitzers are employed by besiegers1st. In a bombardment, by day and night. 2d. During all periods of the siege, when occasion requires. 3d. In the half-parallels established between the second and third; against the covered-ways and places of arms. The fire is executed with small charges. 4th. For ricochet fire, in preference to cannon. 480. Use of fire-balls. Fire-balls are used by the defence1st. Against columns of attack. 2d. Against the opening of parallels, so soon as it is ascertained that preparations are made for this purpose. 3d. Against points in the space occupied by the besiegers, where a remarkable noise may be heard, and there is reason to suspect that it proceeds from preparations for attack. 4th. Particularly when it is thought that the be FIRE OF MORTARS. 499 siegers are about to move forward from one parallel to another. 5th. To discover the movements of the enemy after he has repulsed a sortie, and to prevent him, by the fire of the guns of the place, from following too closely in pursuit.' JIn attack. As it is for the interest of the besiegers to conduct their operations as silently and unobserved as possible, they will seldom have occasion to use fire-balls. 481. Fire of mortars. Mortars generally perform a more important part in siege operations than howitzers; there are times, even, when they play a very decided part; too much care, therefore, cannot be employed to render them effective. In the dcfence. Mortars are employed in the defence1st. Concurrently with howitzers, when the shape of the ground in front shelters the enemy from the fire of the guns. 2d. Against batteries and heads of saps. 3d. Against places sheltered from the fire of flanking guns. - Mortars, and particularly light mortars, can be suitably placed at all points, and without interfering with the establishment of gun and howitzer batteries. 4th. Against the works of the besiegers generally, and especially against the opening of parallels, and the passage from one parallel to another. 5th. When the besiegers' fire has silenced the fire of the guns, the fire of the mortars continues in full activity, not only in the body of the place, but in the demilunes and lateral works. 6th. In covered batteries, during the entire siege, but 500 EMPLOYMENT OF FIELD-ARTILLERY. particularly during or after the construction of the third parallel. 7th. Light mortars should be employed in the counter approaches. 8th. Against the workmen who are engaged in running the sap up the glacis, for the purpose of crowning the covered way. 9th. To prevent the construction of counter and breaching batteries. 10th. To prevent the besiegers from establishing themselves in the craters formed by the mines. 11th. To drive the besiegers from any exterior work which they have taken. 12th. To prevent the passage of the ditch, or render it difficult. 13th. To prevent the besiegers from effecting a lodgment in the breach, by firing from the interior retrench. ment. In the attackc. It is very difficult to specify all the circumstances which should govern the besiegers in carrying on a bombardment, since they depend on a variety'of causes; the following, however, may be enumerated: 1st. In a regular attack, mortars are the first to open fire, which should be kept up night and day whenever a result can be obtained. 2d. Heavy, and sometimes medium-sized, mortars, can be employed to retard the enemy's works on the front of attack, the armament of his batteries, the transportation of his cannon, and to shower shells upon the places where his troops assemble, and to burn his principal buildings, etc. Light mortars are rarely used for these purposes, in consequence of the distance of the object MORTAR CASE-SHOT. 501 and the lightness of the shells, which have little force of percussion. 3d. Mortars are employed to throw shells over the entire surface of the ramparts of the front of attack; and, for this purpose, the fire should be taken in the direction of their length. 4th. They are also employed against the lateral works as soon as the enemy seeks to establish his gunsthere for the purpose of retarding the works of attack. 5th. The curved or mortar fire of the second parallel is as efficient as that of the first parallel, at all periods of the siege. Light mortars here begin to be usefully employed. 6th. Light mortars are also used with great advantage in the half-parallels. From this period of the siege, the covered-way and places of arms are showered with shells. 7th. From the period of the third parallel, the enemy's flanks are plied with mortar shells, to support the fire of the counter batteries. 8th. As soon as the covered-way is crowned, and subsequenitly, when a lodgment in the breach shall have been effected, Coehorn mortars are employed against the enemy, who has withdrawn to the interior retrenchment of the bastion. 482. Mortar case-shot, &c. Stones and case-shot from mortars, should be thrown by the defence as soon as the besiegers pass to the construction of the third parallel, and the batteries pertaining to it. This should be continued during the crowning of the covered-way, and during the assault. The besiegers, on the contrary, employ these projec 502 EMPLOYMENT OF SEA-COAST ARTILLERY. tiles in all the batteries of the third parallel, and, by this means, seek to drive the enemy from the covered way and places of arms, thus preparing the way for the assault. SEA-COAST DEFENSES. 488. Nature of defenses. The means employed for the defense of harbors, are: 1st. Artillery mounted on fortifications, floating batteries, monitors and ships of war. 2d. Channel obstructions, such as rafts, heavy chains, and sunken vessels. 3d. Torpedoes and torpedo vessels, both of which act under water. These means may be used singly, but the most effective defense is made by combining them, according to circumstances. The introduction of steam into vessels of war, and their protection by armor plates have necessitated considerable change in the construction of sea-coast forts and their armament. The best temporary fortifications are made of earth, with large masses in the way parapets, traverses, etc., for covering the guns. It is now proposed to secure a still better covering for the guns by mounting them in iron turrets, similar in shape and construction to the Monitor turrets, but to be,manceuvred by man instead of steam power. Late experiments show that the plan of reveting the masonry of casemated works with wrought-iron plates will not answer, as the iron affords but little protection to the masonry. Monitors as a means of harbor defense have the advantage of being able to select their position of attack and of following an attacking vessel if it should succeed in passing the guns of a fort. The range and accuracy of ARMAMIENT OF SEA-COAST BATTERIES. 503 guns mounted on floating defences are not so great as those of guns mounted on fortifications, and they are liable to be destroyed by rams. Obstructions. The object of obstructions is to detain attacking vessels under the fire of the guns of the forts and monitors. They may consist of rafts of strong timbers, or heavy chains sustained by buoys, or rows of piles, with suitable arrangements to let in or out firiendly vessels. Sunken vessels should only be employed when there is very little commerce to be inter-l fered with, or when it is not practicable to employ other means. Ropes and netting may be placed in a channel to foul the propellors of hostile vessels. Towpedoes. Torpedoes and torpedo vessels were used in the late war in a great variety of forms and with some success. Torpedoes may be made of boxes or barrels covered with pitch, but the largest are made of b)oiler plate riveted together. They are exploded by contact, by electricity, by clock-work or by time-fuzes. 484. Arnmament. The armament of sea-coast batteries depends on their importance and on the depth and width, of the channel to be defended. Deep channels which permit the entrance of large vessels and wide channels requiring long ranges should be defended with guns of heavy calibre. The salients and flanks which generally have an enfilading fire on a channel, should be armed with the heaviest rifle-cannon. The curtains and faces which bear directly upon it may be armed with heavy smooth-bored cannon. In addition to the cannon. enumerated on page 192 as properly belonging to sea-coast armanment, each fort should be provided with a certain number of field 504 EMPLOYMENT OF SEA-COAST ARTILLERY. pieces, principally howitzers, to prevent a landing, or to act in close engagements against the rigging and small boats of vessels. Forts should be provided with furnaces for heating shot which have been found to be effective in protracted engagements with wooden vessels. 485. Fires. Direct, ricochet, and plunging files are principally employed in sea-coast defence. Direct fire should be used when the surface of the water is rough, and the accuracy of the rebound cannot be depended upon. The accuracy of sea-coast fire is generally greater than that of the field or siege service, for the reasons, that, the distance of the object, though moving, can be readily and accurately determined by its relation to known objects, the effect of shot can be more easily observed on water than on land, and the size of the object is large, and its appearance, generally, well defined. In aiming at a vessel with direct fire, the piece should be pointed at the water-line; for, if the projectile strike the water, it will either penetrate the hull below the water-line, or rebound and strike above it. The range of effective direct fire does not much exceed one mile and a quarter; the extreme range of seacoast mortars is about two and a half miles; that of the columbiads, about three and a quarter miles, and the heavy rifle-guns about five miles. The accuracy of ricochet-fire depends on the surface of the water; under favorable circumstances, the larger sea-coast shells have a range of about 3,000 yards in rolling fire; their penetrating force, however, is very much diminished toward the extremity of this range. The fire of mortars, fiom ship-board, is veiy uncertain, if the surface of the water be much disturbed. TABLE ONE. 505 CHAPTER XIII. TABLES OF MULTIPLIERS. B. I, D, V, &c. 487. Explanation. It would exceed the limits of this work to enter into a discussion of the formulas from which the values of the multipliers used in the equations of motion in air (page 412) are calculated; it will be sufficient to explain how these tables are used in practice. The pupil will find this subject, as well as all others relating to Ballistics, ably and fully treated in Didion's Lcraite de Balistique. 488. Table 1. Multiplier B. The decimals are carried out to three places, which is sufficient for ordinary purposes. The values of- are given in the first horizontal line, the value of i in the first vertical colunln, and the values of the corresponding multipliers are set opposite to them. To find the multiplier B for two intermediate values of L and 41, not given in the tables, we seek, in the absence of the proper numbers, the corresponding values of the nearest tabular numbers. We add to these, parts proportional to the differences, as though each part were to be considered separately. 506 TABLES OF MULTIPLIERS. Example.-Find the value of B for _-0.5755, and V=1.1219, C r i. e. B (0.5755; 1.1219). Starting with 0.55 in the first horizontal column, and 1.10 in the first vertical column, we find B=1.479; the difference between this and the next number of the horizontal line is 0.054; the difference between the same and the next number of the vertical column is 0.013. The difference between 0.5755 and 0.55 is 0.0255, and between 1.1219 and 1.10 is 0.0219. The value of B (0.5755; 1.1219)1.479+ 02550.054 + 02190.013= 1.479 + 0.05 0.05 0.027 + 0.006 = 1.512. Or, for greater convenience, the foregoing may be placed in the following form, the differences being written as whole numbers: B (0.5755; 1.1219) —1.512 B (0.55; 1.10) =1.479 255 50054.. 219 13.. - 6 500 iMdtiupltier, I. The values of I are given in the same table as those of B; except that it is necessary to commence in the lower horizontal line, and subtract from them the product of (I+ _), by the corresponding number of the line called " correction." Example.-To find the value of I (0.5755; 1.1219), take -_ C 0.545, which is less than the proposed number by 0.305, and which V, differs by 0.035 from the next number in the table;-'-1.10 is the nearest number to 1.121.9 in the first vertical column; for these two numbers we have 1= 1.771. This number differs from the adjoining horizontal and vertical numbers in the table by 0.066 and 0.022, respectively. The value sought is 1.830, as is thus shown: TABLE Fc;UR. 507 I (0.5755; 1.1219)=1.830 I (0.545; 1.10) =1.771 305 35066 - 58 219 so-22 10 500 -1.1219. 2.1219.4= -9 Table 3. Valrue8 of U and D. This table is calculated for differences of 0.10 in case of x in the upper line, V and for differences of.05 in case of -' For U, the values of - are found in the upper horizontal line, and for D, in the lower line. Ex.ample.-Find the values of U (0.5755; 1.1219) and -D (0.5755; 1.1219). 5U (0.5755; 1.1219)=1.707 D (0.5755; 1.1219)=1.336 U (0.50; 1.10)=1.597 -D (0.393; 110)= 1.221 755 1825 138 ---.104 1920119 -.113 1000 1920 219 219 — 14 -.006 5005 -.002 500 500 We have U=i.707, and D=1.336. Tablo 4. Vcalues of -B for the calculation of PaRnge8. This table gives the value of -B for values of - and for differences of 0.05 and 0.05; the unknown quantity to be determined is c when a and Bp, are given. c r c Arrange the calculations as in the preceding cases. Only one of the proportional parts is unknown, and this is determined by the condition, that if it be added to the other proportional part, and to the number in the table, the sum is equal to the required number. 508 TABLES OF MULTIPLIERS. V, X X Examples. —Having r 1.1219 and -B, or p=0.8729, find -. r ~ C V Starting with -'=1.10, and following the horizontal line, we come r upon 0.8135, the nearest approach to the proposed number, 0.8729. Find X 6x the corresponding value of c, which is 0.55; the unknown value of cC surpasses 0.55 by a certain quantity which we shall call A; following the previous arrangement of the calculation, and observing that the differences of 0.8135 with the adjacent horizontal and vertical tabular numbers are 0.1065 and 0.0071, respectively, and representing byp the result, we havep (0.55+A; 1.1219)=0.8720 p (0.55; 1.10 )=0.8135 A. — 1065 --.0559 0.05 0.0219 050071 -.0035 559 We have Al — -0.05 =-0.0263 x — =0.55 + 0.0263 -- 0.5763 The proportional part 559 is equal to 8729-(8135+35). Table 5. Vcalues of r for initial velocities. This table gives the quotient arising from dividing - by /ff for values of - and; the quantity to be r C r determined is'. The method is the same as in the ~X preceding table; if the value of the quotient q diminishes as - increases, the sign of the difference should be changed. Example.-llHaving = 0.5755, andqr = 0.911:0, find v c A-B r TABLES. 509 The vertical column nearest to — 0.5755 is that which corresponds C to 0.55; the number in this column nearest to 0.9110 is 0.9045, which corresponds to 1.10, and the difference between this and the required number is 0.0065; the differences with the neighboring numbers to the right and above, are - 0.0162 and 0.0370, respectively. We therefore have, q (0.5755; 1.10+A)=0.9110 q (0.55; 1.10) — 0.9045 255 5162 =-.0082 500 o370 --.0147 3.05 147 or A= -- 0.05 = 0.0199 370 and -'=1.10+0.0199=1.1199 r The proportional part 147 is equal to 9110-(9045-82), giving V i\==0.0199, which, added to 1.10 gives —'1.1199. r 5t~~;ED X~TABLES. TABLE 1. —-Values of B and I. r I 0.00 0.05 0.10 0.15 0.20 0.25.300 85 0.40 0.45 I 0.50 0. (0 1.000 1.017 1.034 1.052 1.070 1.089 1 1 l 1. 128 1. 4Q1.69 1.190 0.05 1.000 1.0181 1.036 1.055 1.074 1.0931 1.114 1.184 1.156 1.177 1.200 0.10 1.000 1.019 1.038 1.057 1.077 1.0981 1.119 1 141 1.163 1.1C6 1.210 0.15 1.0001 1.020 1.039 1.060 1.0811 1.103 1.125 1.148 1.171 1.195 1.120 o. 20 1. 000 1.0201 1.041 1.0683 1.085 1.1071 1.1301 1.1.54 1 179 1.205 1.231 0.25 1.0001 1.021 1.043 1.065 1.058 1.112 1.186 1.161 1.1S7 1.21' 1.241 0.30 1.000 1.022 1.045 1.068 1.082 1.117 1.142 1.168 1.19.- 1.223 1.252 0.3; 1.000. 1.023 1.046 1.071 1.096 1.121 1.148 1.15 1.203 1.2'2 1.262 0.40 1.0001 1.024 1.048 1.073 1.0991 1.126 1.1.23 1.182 1.21t 1.241 1.273 1 0.450 1.000 1.025 1.00 1.06 1.1031 1.131 1.159i 1.189 1.219! 1.251 1.283 0.50 1.000 10251.0 1.021 1.107 1.135 1.165 1.196 1.2217 1.260 1.294 80.55:.00 1.026 1.053 1.082 1.110 1.1401 1.171 1.203 125 1.269 1.305.605 1.001 1.027 1.055 1 0849 1.1141 1.1451 1.176 1.209 1.244: 1.279 1.315 I.G5 1.000 1.028 1.057 1.0 S 1.118 1.1491 1.1821 1.216 1.252 1. 28S 1 26 0.70 1.0(00 1.029 1:059 1.090 1.122 1.1541 1.1858 1.224 1.2601 1.2981 1.337 0 0.75 1.000 1.0301 1.060 1.092 1 125 1.1.9 1.194 1.231 1.26 1.308 1.4.s80 1.000 1.031 1.062 1.095 1.121 1.200 1.238 1.21771 1.3 1. 0.85 1.000 1.031 1.064 1.098 1.133 1.169! 1.206 1.'45 1.285 1.3279 1.8370 0 090 1.000 1.032 1.066 1.101! 1.137 1.1731 1.212 1.252 1.-z94 1.3371 1.32 0.95 1.000 1.0331 1.067 1.103 1.140 1.1781 1.211 1,2591 1.8021 1.846 1.393 1.00| 1.0001 1.0341 1.069 1.106 1.144 1.18.1 1.221 1.266 1.8101 1.356! 1.404 1.01.1.000( 1.035 1.071 1.109 1.148 1.188 1.230 1.273 1.319 1.366 1.415 1.. 1 000 1.036 1.073 1.112 1.151 1.1938 1.236 1.2S1 1.32S 1.376 1.427 1.15 1.000 1.037 1.075 1.114 1.155 1.1981 1.242 1.28 1.336. 1.886 1.48.2 1.000 1.081 1.076 1.117 1.1;59 1.203 1.248 1.295 1.341 1.396 1.450,i1.25 I 01.000 1.038 1.078 1.120 11 1.2071 1.2541 1.303 1.3531 1.406i 1.4061 For I I I 0.000 0.033 0.067 0.101 0.134 0.1681 0.202 0.236 0.270 0.304i 0.338 0.00 1.190 1.212 1.234 1.257 1.21 1 305 1.330 1.8,55 1. 3821 1.409 1 437 0.05 1.200 1223 1.247 0.21 1.296 1.322 1.348 10.8751 0.0 11 0. 1.461 0.10 1.210 1.2341 1.259 1.285 1.311! 1:3839 1.366 1.395 1.421' 1.4 5 1 486 0.15 1:220! 1.2461 1.272 1',35 991 1 327 1.385 1.4155 1.447 1.479 1.512 For|0.200 1.231 10.25 0.1.285 1.14 1.341 0.373 1.404 1.436 1 4690 1.503 1.5 10.25 1.241 1.2691.298 1.328 1.359 1.890 1.42.3 1.457 1.491 15 1.486 [ 1 0.20 1.281l 1.258~ 1.285] 1.8143 1.3i 1.373/ 1.404] 1.486/ 1.469 5 1.508 1.56s 0.30 1.2521 1.281 1.311 1.343 1.8375 1.408 1.442 1.477t 1.5141 1.551 1.590 0.35 I1.262 1.293. 1.325 1.357 1.391 1.425 1.461 1.499 1.586i 1.576 1.616 0.40 1.2783 1.8305 1.338 1.3721 1.4071 1.443 1.48 1.520 1.559! 1.601 1.643 0.45.283 1.3171 188 511 1.: 71 14231 1.461 1.500 1.541 1.5S31 1.626 1.670 0.50 1.2941 1.8291 1.3651 1.402 1.4401 1.479 1.520 1.563!1 06 1.606 1 1.697. I o15,5 [~.8o51 1.3411 1.378 1.411 49 1.540 1.584 1.630i 1.67 1.725 0.60 1.315 1.8 53 1.892 1.4832 1.473' 1.516 1.5601 1.e06 1.6541 1.70, 1.58 0.65 1.826 1.3(51 1.406' 1.447! 1.4901 1.535 1.581 1.629 1.629 1 1.67 29 1.781 [ 0.70 1.3! 1 1.378 1.420 1.46:1 1.507 1.553 1.601 1.651 1.70l 1.7l55 1.810 0.75 1.84S 1.:.90} 1..433 1.478[ 1.5241 1.572 1.622 1.674 1.727! 1.782 1.839 0.80 1.359 1.403 1.441 1.4941 1.542 1.591 1.64.3 1.6961 1.751 1.809 1.868 0.85 1.370 1.415 1.462 1.5091 1.559! 1.610 1.664 1.719 1.776, 1. 36 1. 97 0.90 1.38. 1.4281 1.476 1.5251 1.577 1.630 1.6850 1.7431 1.802 1.8650 1.927 0.95 1.393 1.440! 1.490 1.541! 1.5941 1.649[ 1.706 1.766 1.8Z7' 1.S91 1.957 1.00 1.4041 1.453 1.504 1.557! 1.612 11.669 1.728 1.789 1.853 1.919 1.957 1.05 1.415 1.466] 1..5731 11 1630: 1.688 1.749 1.8131 1.879[ 1.947 2.017 1.10 1.427 1.479 1.5:3- 1.590i 1.648 1.708 1.771 1.837i 1.905 1.975 2.048 1.15 1.438 1.49-2 1.548 1.606' 1.666 1.728 1.793 18.611 1.931! 2.0(04 2 079 I 1.20 1.450 1.5(15 1.563 1.623i 1.684! 1.749 1.816 1.886 1.951 2.0833 2.111 F1.25 1.461 1.518 1.578 1.6391 1.703 1.769 1.8-38 1.9101 1.,851 2.062 2.142 For 3 I l c 0.383S 0.372 0.407 0. 441 0.476i 0.511 0.545 0.580 0.6151 0.6501 0.6S5 Correction.... 0.001 0.0021 0.002 0.002 0. 008 0.0041 000040 0.005 I0.0051 0.006 00. 0 00 TABLES. 511 Values of B and 1. -(Contiued.) r C 1.80 i For 1.001.05 1.10 1.15 1.201.25 1.0 1.5 1.40 1.,45 11.50 B e 6.00 1.43, 1..465 1.494 1.5-25 1.556 1.588 1 -.621- 1.654 1 689 1251 1.762 0.05 1.461 1.492 1.5231 1.5551 1.588' 1.6221 1.6571 1.693 1.730 1.7681 1.808 0.10 1.486 1.519 1.5521 1.586j 1.621 1.6571 1.6941 1.732 1.772! 1.812! 1.854 I 0.15 1.512 1.546 1.581 1.6201 1.6,54 1.6921 1.'821 1.72 1.814 1. S571 1.902 0.20 1.538 1.5738 1.610 1.649 1.688! 1.728S 1.770 1.813 1. 857 1 9030 1.950 0.25 1.56- 1.6011 1.640 1.681 1.722 1.765 1.809 1.80 854 1.901 1.949 1.999 O.30 0 1 5. 1.629 1.670[ 1.713 1.7157 1.802 1.848 1.896 1.945 1.9961 2.049 0.35 1.r16 1.658 1.701 1.746 1.792 1.S889 1.888 1.938 1.990 2.04 4 2.100 0.40 1.643 1.687 1.732 1.779 1.827 1.877 1.928 1.981 2.036 2.098j 2.151 0.45 1.670 1.716 1.763 1.812 1.868 1.915 1.969' 2.0251 2.088 2.1421 2.208 0.50 1. 97 1.7451 1.795 1.846 1.899 1.954 2.01 1 2.069 2.129 2.192' 2.256 0.55 1.725 1.7751 1.827 1.881. 1.936 1.993 2.0,31 2.114 2.177 2.2421 2.810 0.60 1.7.3 1.8051 1.859 1.9151 1.973 2.033 2.0951 2.159 2.225 2.2983 2.364 0 6 0.65 1 1.8361 1.S921 1.950 2.011 2.073 2.13881 2.205 2.274 2.3451 2.419 >. / 0.70) 1:.81 1.8661 1.925 1.986 2.049 2.114 2.182] 2.251 2.828! 2.8981 2.475 0.75 1.889 1.897 1.958! 2.0221 2.085 2.155 2.226i 2.298 2.373T 2.451 2.532 0.]0 1.868 1.929 1.9921 2.058! 2.127 2.197 2.2701 2.3461 2.4241 2.505 2.589 0.85 1.897 1.960 2.026 2.0951 2.166 2.239 2.3'15! 2.894 2.4751 2.560 2.648. 0.90 1.9'27 1.992 2.0611 2.132 2.206 2.2821 2.861! 2.448 2.5271 2.6161 2.707 0.95 1.957 2.025 2.0961 2.169 2.246 2.825 2.407 2.4921 2.5801 2.6721 2.766 1.00 1.987 2.057 2.1311 2.207 2.287 2.369 2.454 2.542 2.6338 2.728 2.827 1.05 2.017 2.090 2.167T 2.246 2.328 2.418 2.501 2.5938 2.6871 2.7861 2.888 1.10 2.04S 2.127 2.203 2.284 2.870 2.458 2.549i 2.644 2.742 2.8441 2.950 I 1.15 2.079 2.157 2.240 2.323 2.412 2.503 2.5971 2695 2.797 2.903 3.013 1.20 2.111 2.191 2.276 2.8681 2.454 2.548 2 6461 2.748] 2.858 2.9631 8.076 1.25 2.142 2.225 2.813 2.4083 2.497 2.594. 2.6961 2.801 2.909 8.0283 3.141 For a1 1 1 1I 0.685 0.721 0.756 0.791 0.827 0.863 0.8991 0.934 0.9701 1.006 1.043 =' For 11.950 2.00 For 1.50 1 1.55 1.60 1 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 B I e l'l l!, l l W F F1 0.00 1.7621 1.799 1.8381 1.87s 1.920 1.9621 2.006 2.051 2.0971 2.145 2.194 0.05 1.80 4 1.848 1.890 1.933 1.977 2.022! 2.069: 2.117 2.167 2.21S 2.271 0.10 1.8541 1.S97 1.942 1.9885 2.035 2.088 2.1838 2.185 2.2381 2.293! 2. 49 0.15 1.902 1.94q 1.9995 2.0441 2.094 2.145 2.199] 2.254 2.8101 2.:4691 2.429 0.20 1.950 1.999 2.049 2.101! 2.154 2.209 2.265] 2.824 2.884 2.4461 2.511 0.25 1.9991 2.051 2.104 2.158! 2.215 2.278 2.883 2.895 2.459 2.525! 2.t94 0.80 2.049! 2.103 2.159 2.2171 2.277 2.899 2.402 2.468 2.586 2..06 2.678 0.35 2.1001 2.157 2.2161 2.277 2.340 2.405 2.478 2.542 2.614 2.688& 2.75 0.4? 2.151 2.211' 2.2741 2.389] 2.405 2.473 2.544 2.617 2.693 2.771! 2.852 0.45 2.2031 2.267' 2.8s 2 2.400 2.470 2.542 2.*171 2.694 2.774 2.857! 2.942 0.50 2.2561 2.823 2.3911 2.468 2.536 2.ti6l 2.691 2.772 2.'56 2.9431 8.083 0.55 2.310! 2.30 2.452 2.526j 2.604 2.683 2.766 2.851 2.940 8.0311 3.126 0.60 2.864' 2.437! 2.5181 2.591! 2.672 2.75' 2.842 2.932 8.025 8.1211 8.220 0.65 2.419 2.4'6! 2.575' 2.6571 2.742 2-.829 2.920 3.014 3.111 R.212 3.8.16 0.70 2.475 2.555 2.e381 2.728 2.812 2.904 2.999 8.097 3.199[ 8.304i 8.413 0.75 2.532 2.615 2.702 2.791 2.8z4 2.979:4.079 8.181 8.288.8981 8.512 0.I0 2.589I 2.676 2.761 2.860 2.956' 8.056 8.160i 3.267 3.8791 3.494 8.613 0.85 2.643! 2.788 2.8821 2.929 8.080 8:.184 3.242 3.: 54,.471 8.591! 3.715 0.90 2.707! 2.801 2.S981 8.000 8.105 3.218 3.826 2.443 3.5641 8.6891 3.819 0.95 2.766 2.864 2.966 8.071 8.180 8.2.8 8.411 3.582 3.659 8.7901 3.925 1.00 2.827 2.928 3.084 8.144 8.257 3.375 8.497 38.623 8.755 8.891 4.082 1'.05 2.884 2.998,1 8.10(8 3.217 3.385 8.4.57 3.5841 3.716 8.852 3.994 4.141 1.10 2.950 8.0591 3.173 8.291 3.414 S8.541 8-.678 8.809 3.951 4.0991 4.251 1.15 38.018' 8.1261 3.244 3.867 3.494 8.125 8.762| 8.904 4.052 4.205! 4.'i63 I 1.20 38.0761 8.194! 3.8316! 8.4483 3.575 8.711 83.858 4.000 4 153 4.8121 4.477 1.25 8.1411 8.262! 8.889! 8.520 8.657 8.798 8.945 4.098 4.2571 4.4211 4.592 I1 or 5 1 1 c 1.043t 1.079. 1.1151 1.151 o.181 1.225 1.261 1.298 1.3351 1.872! 1.409 Corllection.... 0.015! 0.017! 0.018, 0.019! 0.021 0.022 0.0241 0.0251 0.02T, 0.029, 0.031 512 TABLES. TABLE 3.-Values of U for velocities and 2D for times. For | 0.00 0.10 0.20 0.80 0.40 1 0.50 0.60 0.70 0.80 0.90 1.00 000 1.000 1.051 1.1051 1.162 1:.221 1.284 1.350 1.41.9 1.492, 1.568 1.649 0.05 1.000, 1.054 1.110 1.1701 1.2338 298 1.867 1.440 1.516 1 597 1.681 0.10 1.000 1.056 1.116 1.1781 1.244 1.312 1.885 1.461 1.541 1.625 1.714 0.15 1.000 1.059 1.121 1.1861 1.255 1.K27 1.402 1.482 1.566 1.654 1.746 0.20 1.000 1.062 1.126 1.1941 1. 26 1.341 1.420 1,503 1.590 1.682 1.779 0.25 1.000 1.064 1.182 1.2021 1.277 1.355 1.437? 1 524 1.615 1.710 1.811 0.30 1.000 1.067 1.137 1.210' 1.288 1.869 1.455 1.545 1.e39 1.739 1.843 0. 35 1.000 1.069 1.142 1.219 1.299 1.388 1.472 1.566 1.664 1. 767 1.876 0.40 1.000 1.072 1.147 1.227 1.310 1.898 1.490 1.58i 1.689 1.796 1.908 0.45 1.000 1.074 1.153 1.235 1.821 1.412 1.507 1.608 1.713 1.824 1.941 0.50 1.000 177 1.158 1.243 1.332 1.426 1.525 1.629 1.738 1.853 1.973 0.55 1.000 1.080 1.163 1.251 1.843 1.440 1.542 1.650 1.762' 1.881 2.006 0.60 1.000 1.082 1.1681 1.259 1.8,54 1.44 1.560 1.671 1.787 1.909 2.088 0.65 1.000 1.085 1.1741 1.267 1.365 1.469 1.577 1.6q2 1.812 1..38 2.070 0.70 1.000 1.0O7 1.179 1.2751 1.376 1.483 1.595 1.712 1.836 1.966 2.103 0.75 1.000 1.0.0 1.184 1.2831 1.388 1.497 1.612 1.7383 1.861 1.995 2.135 0.80 1.000 1.092 1.189 1.291 1.399 1.511 1.680 1.754 1.885 2.023 2.168 0.85 1.000 1.095 1.195 1.299 1.410 1.525 1.647 1.775 1.910 2.051 2.200 0.90 1.000 1.097 1.200 1.308 1.421 1.540 1.665 1.796 1.935 2.080 2.233 0.95 1.000 1.100 1.205 1.816 1.432 1.554 1.682 1.817 1.959 2.108 2.265 1.00 1.000 1.103 1.210 1.3241 1.44 1.53 1.700 1.838 1.984 2.137 2.297 I 1.05 1.000 1.105 1.216 1.332 1.454 1.582 1.717 1.859 2.008 2.165 2.:-30 1.10 1.000 1.1081 1.221 1.340 1.465 1.597 1.735 1.880 2.033 2.1941 2.362 I 1.15 1.000 1.110 1.226 1.848 1.476 1.611 1.752 1.901 2.057 2.222 2.395 1.20 1.000 1.113 1.231 1.856 1.487 1.625 1.770 1.922 2.082 2.2501 2.427 -1.25 1.000 1.115 1.237 1.364 1.498 1.629 1.787 1.943 2.107 2.2791 2.460 F'or a| D I 0.000 0.198 0.393 0.585 0.775 0.962 1.146 1.827 1.506 1.683 1.858 For | 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00i rI 0.00 1.649 1.7331 1.822 1.916 2.014 2.1171 2.226 2.840 2.460 2.586 2.710 0.05 1.681 1.770' 1.863 1.961 2.064 2.173 2.287 2.407 2.533 2.665 2.804 0.10 1.714 1.807 1.9041 2.007 2.115. 2.229 2.848 2.474 2.6061 2.744 2.890 0.15 1.746 1.843 1.945 2.05381 2.1661 2.2851 2.409 2.541 2.679 2.8241 2.976 0.20 1.779 1.8801 1.9871 2.099 2.2171 2.8401 2.471 2.608 2.752 2.908 8.062 0.25 1.811 1.91.7 2.028 2.1441 2.2671 2.896 2.532 2.675 2.825 2.9821 3.148 0.80 1.843 1.9531 2.069 2.1901 2.83181 2.452 2.593 2.742 2.89 83.064 8.234 0.85 1.876 1.9901 2.110 2.2361 2.869j 2.508 2.655 2.809 2 971 3.141 3.820 0.40 1.908 2.0271 2.151 2.282i 2.419i 2.564 2.716 2.876 3.044 3.220 3.406 0.45 1.941 2.063 2.192 2.3281 2.4701 2.620 2.777 2.943 3.116 3.299 3.492 0.50 1.97T1 2.1001 2.2833 2.373 2.521 2.676 2.838 3.010 3.189 3.879 8.577 0.55 2.006 2.137 2.274 2.419 2.571 2.731 2.900 3.077 3.262 3.458 3.663 1 0.60 2.038, 2.173 2.315 2.465 2.6221 2.787 2.961 3.143 8.351 3.537 3.749 0.65 2.070 2.210 2.857 2.511 2.678 2.8483 8.022 8.210 3.40S 3.616 3.S35 qi 0.70 2.103 2.247 2.398 2.556 2.723 2.899 3.083 3.277 3 481 3.696 3.921 0.75 2.135 2.e883 2.4391 2.602 2.774 2.955 8.145 38.844 35541 3.775 4.007 0.80 2.168 2.320 2.480 2.648' 2.825 3.011 3.206 8.411 3.6271 3.8541 4.093 0.85 2.200 2.3571 2.521 2.6941 2.875 3'.066 3.267 8.478 3.7001 8.98833 4.179 0.90 2.233 2.8931 2.562 2.740 2.9261 3.122 3.829 3.545 3.773 4.013 4.265 0.95 2.265 2.430 2.603 2.785 2.977 3.178 3.8390.612 3.846 4.091 4.351 1.00 2.297 2.467 2.644 2.831 3.0281 8.234 3.4511 3.679 3.919 4.171 4.487 1.05 2.3880 2.5038 2.685 2.877 3.078' 3.290 8.5121 3.746 3.992 4.251 4.523 1.10 2.862 2.540 2.726 2.9238 8.129 3.3461 8.5741 3813 4.065 4.330 4.608 I 1.15 2.895 2.577 2.768 2.96S 3.180' 3.402. 3.635 38.880 4.138 4.4091 4.694 1.20 2.427 2.613 2.809 3.014 3.2301 3.4571 8.6961 3.947 4.211 4.489 4.780 L 1.25 2.460 2.6501 2.850 3.0601 8.2811 3.5181 3.758 4.014 4.284 4.5681 4.866 For x i... -.D 1.85S; 2.030 2.199 2.369 2.5351 2.7011 2.864i 3.026 8.186 3.3441 3.501 _ _ _._ _ I I TABLES. 513 TABLE 4.-Values of $B for ranges. 0.00 0.05 0.10 1 0.15 0.20 0.25 0.30 1 0.35 0.40 0.45 0.50 0.00 0.000 0.0508 0.103410.1578 0.21400.2722 0.8824 0 3947 0.4591 0.5258 0.5949 0.05 0.000 0.0509 0.1086 0.1582 0.2148 0.2734 0.3341 0.39700.4622 0.5298 0.6000 0.10 0.000 0.0509 0.1038 10.158610.2155 0.2745 0.3857 0.3993 0.46540 5839 0.6051 0.15 0.000 0.051010.1039 0.1590 0.2162 0.2757 0.337410.401710.4685 0.5379 0.6102 0.20 0.000 0.05100.104110.159410.2169 10.2768 0.88391 0.4040 0.4716 0.5420 0.6154 0.25 0.000 0.0511;0 1048!0.159810.2177 0.2780 0.340810.406410.4748 0.5461 0.6206 0.30 0.000 0.051110.104510.1602 0.2184 0.2791 0.3425,0.408810.4780 0.5503 0.6258 0.85 0.000 0.051110.1046 0.1606!0.2191 0.2808 0.344380.4112:0.4812 0.5544 0.6310 0.40 0.000 0.0512!0.104810.161010.2199 0.2815 0.3460 0.4136 0.4844 0.5586 0.6363 0.45 0.00010.0512 0.1050 0.1614:0.2206 0.282610.347710.416010.4877 0.5628 0.6416 0,50 0.000 0.05180.1052 0.1618 0.2213 0.28388 0.349410.41840.490910.5670 0.6470 0.:55 0.000 0.0513i0.105810.1622 0.2221 0.2850 0.351210.4209 0.4942 0.5712 0.6528 0.60 0.000 0.0514 0.1055 0.1626,0.2228 0.2862 0.352910.4233 0.4974 0.5755 0.6577 0.65 0.000 0.0514:0.1057 0.1630 0.2236 0.2874 0.354710.4257 0.5007 0.5797 0.6632 0.70.0000.05140.105910.16340.22430.2886 0.356410.428210,5040 0.5841 0.6686 0.75 0.0000.05150.1060!0.163810.2250 0.2897 0.358210.430710.5074 0.5884 0.6741 0.80 0.00010.0515'0.1062 0.164380.2258 0.2909 0.860010.433210.5107 0.5927 0.6796 0.85 0.000;0.0516,0.1064!0.1647i0.2265 0.2921 0.361710.4356 0.5140 0.5971,0.6852 0.90 0.000 0.0516 0.106610.165110.2273 0.2933 0.3635 0.4381 0.5174 0.6015 0.6908 0.95 0.000 0.051T;0.1067 0.1655i0.2280 0.2946 0.8658 0.4407 0.5208 0.6059 0.6964 1.00 0.000 0.0517 0.1069 0.165910.2288 0.2958 0.8671 0.4432 0.5242 0.6103 0.7020 1.05 0.000 0.051710.1071 0.166310.2295 0.297010.3689 0.44571 0.5276 0.6147 0.7076 1.10 0.000 0.0518 0.107310.166710.2803 0.29820.38707 0.4482!0.583100.6192 0.7188 1.15 0.00010.0518 0.1075 0.167110.2310 0.2994 0.3725 0.45080.58344 0.6287 0.7191 ]1.20 0.00010.0519 0.1076 0.1676 0.281810.3006 0.8743 0.453310.5879 0.6282 0.7248 1.25 0.000 1.0519.1078 0.16800. 2326 0.8019 0.8761 0.4559 0.541410.6827 0.7806 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 0.00 0.5949 0.6664.0.7404i0.8171 0.89640.9786'1.06381.1521,1.2435 1.8884 1.4865 0.05 0.6000 0.672710.7480 0.8262:0.9072 0.9912 1.0784 1.1689 1.262811.3603 1.4618 0.10 0.6051 0.6789l0.7556 0.835310.9180 1.0039 1.0931 1.186011.2823l1.3825 1.4864 0.15 0.6102 0.6852 0.763880.84450.9290 1.010711.1080 1.2031 1.8020 1.4050 1.5118 0.20 0.6154 0.6916 0.7711 0.853810.9400 1.02961.1230 1.2205 1.821911.42761.5375 0.25 0.620610.6981 0.7789 0.868210.9511 1.0427!1.1882 1.2880 1.420!1.4505 1.5634 0.30 0.625810.7045 0.7868 0.87260.9623 1.0558 1.1535 1.255811.3622 1.47836 1.5896.5 0.6810 10.7110 0.7947 0.88220.978611.0691 1.1690 1 2737 1.882811.4970 1.6162.40.6368 0.7175 0.802710.8917 0.985011.0824 1.1846 1.2917 1.4085'1.5207 1.6480 0.45 0.6416 0.7241 0.8107 0.9014 0.996411.095911.2002 1.8099 1.42481.5445 1.6701 0.50 0.6470 0.780710.8188 0.9111 1.0080!1.1095 1.2161 1.8282 1.44551.5686 1.6974 0.55 f0.6523 0.78374 0.826910.9209I1.0196j1.122 11.282111.3467 1.46671.593011.7251 0.60 0.6577 0.744110.8851 0.9807 1.0318 1.1370l1.248211.3654 1.4882 1.6176 1.7580 0.65 0.6682 0.7509 0.8 4340.9407!1.04311.1510 1.264511.38853 1.51001.6424 1.7813. 0:.70 0.668610.7577 0.85171 0.950711.0551i1.1650 1.280911.4084!1.5819 1.6674 1.8098 0.75 0.6741 0.7645 0.8600 0.9608 1.06711.1791 1.297411.4225 1.5539 1.6927 1.8386 0.80 0.679610.7714 0.868410.9709 1.079211.19388 1.314111.441911.576811.71881.8676 0.85 0.685210.7783 0.8769 0.9811 11.091411.207711.38091.461411.59881.744011.8970 0.90 0.6908 0.7852 0.8854 0.9914 1.108611.222211.847811.4811 1.6215 1.770011.9267 0.95 0.6964 0.79220.89401.0018 1.11591.2868 1.8649 1.5009 1.6444 1.7964 1.9566 1.00 0.7020 0.79983 0.90261.0122 1.128411.2515{1.882111.5210{1.6675 1.82291.9868 1.05 0.7076 0.8064 0.9118 1.0226 1.140911.266.3 1.8995 1.541111.6909 1.8495 2.01783 1.10 0.718833 0.8135 0.9200 1.03881.1535 1.28121.4170 1.5615 1.71441.876412.0481 1.15 0.7191 0.82060.9289 1.0489 1.1668 1.2968 1.4346 1.5819 1.7882 1.903712.0792 1.20 0.724810.8278 0.9377 1.0546 1.1791 1.311511.4524 1 6027 1.7621 1.981212.1105 1.25 0.7806 0.8350 0.94661.0654 1.1920 1.326811.4702 1.6286 1.7861 1.958812.1422 33 51 4 TABLES; V, TABLE 5.-Values of r for initial velocities. VB _ 0.00 0.05 0.10 0.15 0.20 00.25 0.30.85 0.40 0.45 0.50' 0l- o. o. io. I. o.. o. o. o. ).05 0.0000.04956.04913.04869.04825.04782.04788.04695.04651.04608. 04564 0.10 0.0000.09908.09816.09725.09634.09543.)9452.09362.09271.09181.,-9091 0.1 0.0000.14857.14711.14569.14426.14284.141483.1401.13860.13719.13778 I 0.0000.19800.19601.19402.192o4.19)7.18811.18614.18418.18223.18028.25 0.0000.24739.24480.24221.239631.23708.23454.23200.22945 1.22692.22440 0.30 0.0000.29675.29851.29029.28710.28392.28075.27759.274441.27130.26818 0.35 0.0000 0.3461 0.3422 0.388830.33440.33060. 267.3229 0.319110.815310.3116 0.40 0.0000 0.3953 0.390 0.8861.3815 0.38770 0.83725 0.3680 0.3635 0.8590.546 0.45 0.0000 0.4446 0.4392 0.433818.4285 0.4232 0.4180 0.4128 0.4075 0.4024 0.3973 0.50 0.0000 0.493880.487610.481510.4754 0.4693 0.4633 0'.4573,.4513 0.4454 0.4896 0.55 0. 0000 0.5429 0.5359 0.528910.5220 0.5152 0.5084 0.5016 0.4948 0.4881 [).4815 1 0.60 0.0000 0.5920 0.5841 0.5762'0.5685 0.560810.553210.5456,,.5380 0.5305.5281 0.65 0.0000 0.641110.6323 0.6235 0.6148 0.6063 0.5978 o.58941,.5810 0.5727 0.5645 0.70 0.000 0.690110.6803 0.6706 0.661010.651610.6422r.6329 0.623610.6144 0.6053 0.75 0.0000 0.73910.7288 0.7176 0.7071 0.6967 0.6864 (,6761 0.6659 0.6558 0.6459 0.80 0.00 01.7880 0.77621). 7645:0.75830 0.7416!0.7803 0.7191 0.7080 0.6971 0.6862 0.85 0.000 1 0.8370 0.8241 0.8113 0. 7987 0.786810.7741 ".7619 1..7498 0.7379 0.7261 0.90 0.000 0..885710.8710..8579j0.8443 0.8309 10.8176 0.8044 0.7918 0.77840.7657 0.95 0.0000 0.984710.9195 0.9045'0.8897 0.8752 0.8609, 1.84670.8327 0.8188 0.8051 1.00 0.0000,0.9834 0.96710.95090.9349 0.919410.9(400.8887 0.8736 0.8587 0.8439 1.05 0.0000 1.0322 1.0145 0.997110.9801 0.96340. 9469 0.9305 0.9143'.8984 0.8826 1.10 0.0000 1.08091.0620 1.01434 1.0251 1.0072 0.989510.9720 0.9547 0.9377 0.9210 1.15 0.00001.1295 1.10941.0895 1.0700 1.0508 1.083201.0134 0.9949 0.9768 0.9590 I 1.20 0.00001.1781 1.15661.13541.11461.09421.07411.054 1.03481.0156 0.9967 / 1.25 0.0000 1.2267 111.2038 1.11 1. 159211 137511.116211.0952 1.074511.0541 1.0341 0.50 0.55 10.60 0.65 0.70 0.75 0.80 1 0.85 0.90 0.95 1.00 C I lo- 1~- 0. o. o. o. o. o. o. o. I. 0.05 1.04564.04521.04478.04485.04892.04349.04806.042638.04221.04178.04136 0.10 i.09091.09001.08911.08821.087821.08644.085551.08466.08378.08289.08202 0.15 1.13778.13438.13299.13160.13,,21.12883.12746.12608.12471.12334.12198 0.20 1.18128.178351.17648.17451.172591.17069.16880.16691.16503.163151.16128 0.25:.22440.22190.21942.21694.214481.21203.20958.20715.20473.20233.19994 0.30,.26818.26507.261981.25890.255881.25285.24988.24682.243883.24087.23793 0.35 11.3116 0.3078 0.3041 0.38 04 0.2968i0.2932 0.2895 0.2859 0.2824:0.2788 0.2753 0.4,) I,).354610.8502 0.3458 1".4150.337210.333() 0.3287 0.324 50.3203 0.8162 0.8121 0.45 i.8397310.392210.8871 0.3821 1.87721]t.3728 11.3674 0.3625 0.8577 0.85290.3482 I.50 0.439610.4881 0.4280 0.4223 0.416710.4111 0.4055 0.4000 0.8945 0.3891 0.3888 0.55 0.481510.4750 0.488504621 0.462 10.45570.440.44820.437010.430810.42470.4187 0 60 0.5281 0.51580.5086 0.5014,.4948 0.4873 0.4804 0.4785 0.4666 0.459810.4581 0 65 0.5645 0.556810.5488 0.5408 0.58325 0.5247 0.5170 0.5093 0.501810.4944|0.4870 0.70 10.6053 0.5964/0.587510.5788(.57,0210.5616 0.5532 (.5448 0.536510.528410.5203 0.75 0.645910,6361 0.6264 0.6169 0.6(075 0.5981,.5889 0.5798 1'.5708 0.561910.5531 1 0.80 0.6862.0.6755 0.6650 0.6546..6443 0.6342 10.6242 0.6143 0.6045 0.594910.5854 0.85 10.7261 0.7145 0.7081 0.69190.6808 0.6698 0.6589 0.648210.637710.627310.6171 0I.0) 10.7657[0.7532,0.740910.7288 0.71680.7' -5010.698410.681910.670610.659410.6484 I 0. -. 0.8051'.7916 0.778310.7652 0.75240.7398 0.72781 (.7149 0.7028{0.6909 0.6792 1- 0 0.84891() 8295 0.8153 0.8014.78761.7741 0.7608 ".7476 1 0.7341 0.7219 0.7094 1.05 0.88261.8671 0.8520 0.8371 0. 82250. 8081 0.7939 0.7798 0.7660 0.7525 0.7393 1.ln!0.921010.904510.8888 0.8725 0.857010.8417 0.8265 ".8116 0.7970 0.7827 0.7686 1.15 10.9590/0.941510.9243 0.94!75 0.890910.8747 0.8588 0.8480 0.8275 0.812410.7975 1.2o 10.996710.9781 0.9599 0.9421 0.9246i0.907510.8906 108789 0.857610.841610.8260 1.25 ll0841i1l.0145 0.9958 0.9764100.9579 0.9898 0.9220 0.9045 0.887830.8705 0.8540 I ~ I1II.2II5 TABLE FOR BALLISTIC MACHINE. 515 TABLE of Timres, calculated for the WEST POINT BALLISTIC MACHINE. 2rl 1 Length of simple pendulum, 5.769 in.; and -0.001509". 360//2gl Time of Time of Degrees. passage for Sum of Times. Degrees. passage for Sum of Times. each degree. each degree. 1.00151. 26.00159.03987 2.00151.00302 27.00159.04146 3.00151.00453 28.00160.04306 4.00151.00604 29.00161.04467 5.00151.00755 30.00162.04629 6.00151.00906 31.00163'.04792 7.00151.01057 32.00163.04955 8.00151.01208 33.00164.05119 9.00151.01359 34.00165.05284 10.00152.01511 35.00166.05450 11.00152.01663 36.00167.05617 12.00152.01815 37.00168.05785 13.00152.01967 38.00170.05955 14.00153.02120 39.00171.06126 15.00153.02273 40.00172.06298 16.00153.02426 41.00173.06471 17.00154.02580 42.00175.06646 18.00154.02734 43.00176.06822 19.00155.02889 44.00178.07000 20.00155.03044 45.00179.07179 21.00156.03200 46.00181.07360 22.00156.03356 47.00182.07542 23.00157.03513 48.00184.07726 24.00157.03670 49.00186.07912 25.00158.03828 50.00188.08100 EXAMPLE.-What is the velocity of a projectile when the time of its passage between two targets, 100 feet apart, corresponds to 20.5 degrees of the graduated arc? Time of 20 =- 0.03044 Log. of 100 - 2.000000 Add for 0.5~ 0.00077 Log. 0.06242 - 2.795324 Time of 20~.5 = 0.03121 Log. 1602. = 3.204676 2 Double arc - 0.06242 Velocity = 1602. feet. TABLES OF FIRE. WITH the exception of those for mortars, the following tables of fire were calculated by Bvt. Brig.-Gen'l J. A. HASKIN, U. S. Artillery, by aid of the equations of the movement of projectiles in air given in Chapter VIII., and so far as they have been verified they agree remarkably we'l with those obtained in practice. The "range" is understood to be the distance in yards at which the projectile first strikes the horizontal plane drawn through the centre of the muzzle of the piece. When the object is situated below this plane the angle of elevation of the piece, if measured by the quadrant, should be corrected by the table on page 532.; In aiming at the object direct, with the breech-sight, no correction for the elevation of the piece is considered necessary, if the angle of elevation or depression of the object does not exceed 15~. The weight of each projectile, the value (c), and the initial velocity (I. V.), are given in the tables in each case. RANGES. 517 Ordnance. Charge. Projectile. Elevation. Range. Time. Remarks. o0 Yards. Seconds 6 Pdr. Field Lbs. SHOT..30 298 Gun. I.2 I. 507 Wt.-6.I5 lbs. I. 30 670 c.zz66o 2. 804 2. 30 918 3. 30 iIo6. 118i4 5 I1323 6. I442 7. 1 1546 8. 1638 9. 1721 10. I1796 -30 328.77 I.25 SPHERICAL. I. 537 1.44 CASE. I. 30 697 2.07 2. 827 2.65 Wt. =5.51bs. 2. 30 936 3.I8 e3. 1,030 3.68 C.=2379 30 1112 4.17 I. V.__I550 4- 1x86 4.62 5 1315 5.52 6. 1425 6.36 7- 121 7.I4._.5 I81 -.1 Ranges obtained I12 Pdr. Field 2.5 SHOT..3 320 at Washington Gun..45 452 Arsenal, Wt.=I 2.3 lbs. I. 562 March, 1865. 333 15 662 o / Yards I. 30 750 I.V.=I486 I. 45 832 1. 599 Z. 906 1. 30 750 2. 30 0I 40 2. 875 3 - 1158 2. 30 1050 3. 30 I26I 3. 1185 4. I355 3.30 1280 5 1521 I 4. 1860 6. 1663 5. 1520 7. 1788 8. 1899 9- I1999 I 0. 2090.30 324.77 2 5 SPHERICAL I. 554 1.45 CASE. I 30 733 2.09 2.!882 2.65 Wt 2 30 1010 3.25 C'305 3 3. 30 1I28 4.3 I. V.=I4.95 4. 1307 4.8I 5. I1462 5.73 6. 1595 6.62 I 1 1711 7.46 I. |I815 8.27 9.- 1907 9.05 IsI | Io. I992 9.82 I 5 1-8 RANGES. Kind of Ordnance. Charge. Projectile. Elevation. Range. Time. Remarkl. 0 / Yards. Seconds I2 Pdr. Field Lbs. SHELL..30 367.82 Gun. 2.5 I. 590 1.52 Wt.o:9 lbs. 1.30 765 2.I8 c.2442 2. 900 2.78 2.30 1014 3.36 3. 1112 3.88 3.30 1197 4.36 4. I 274 4.84 5. I408 5.75 6. 152I 6.57 7. I16I9 7.42 8. I706 8.19 9. I784 8.92 10. 1855 9.64 II. 1919 o0.34 I2. 1979 I.98.30 232 -.64 12 Pdr. Field I. SHELL. I. 405 I.23 Howitzer. 1.30 545 1.78 Wt.= —9 lbs. 2. 662 2.30 C.=2442 2.30 1763 3 2.77 3. 850 3.26. V=I239 330 930 3.72 4. Ioo002 4.15 5. 1127 5. 6. I235 5-79 7- I329 6.54 8. 1413 7.26 9' I488 7.95 10. I556 8.6i.30 214.6i I, SPHERICAL I. 385 1.I8 CASE. 1.30 529 1.72 2. 653 2,24 Wt.= I.25 2.-30 763 2.73 3. 859 3,2I e.=3053 33.30 947 3.67 I. V.=I I60 4- I028 4.12 5. 1171 5. 6. I295 5 79.30 233.64 24 Pdr. Field 2.5 SHELL. I. 4I5 I.23 Howitzer. I. 30 566 1.79 Wt.z-17.51bs. 2. 695 2.32 2. 30 807 2.83 3. 906 3.32 I.V.-I220 3. 30 996 3-79 4- Io078 424 5- 1222 5.11 6. 1 348 5.95 7. I457 6.75 8. 1556 7.5 9. 1646 8.24 10. I 726 8.95 RANGES. 51 9 Krdnance. Charge. Projectile. Elevation. Range, Time, Remarks. 0 / Yards. Seconds 24 Pdr. Field Lbs. SPHERICAL.30 I 5.6 I Howitzer. 2.5 CASE. I. 396 I,.I -I.30 551 174 Wt.=22.46 2. 688 2.27 C.2,30 80 2-78 Cc~.=386o 33 - 3.28 IV.=I I 50 3.30 020 3.76 4. 111 4-23.5, 1278 5-13 6. 1423 5-99 7. 1552 6.8I 8. 1669 7.61 9, 1775 8.39 Io. 187I 9.I3 _30 223.,63 32 Pdr. Fieldl 3.25 SHELL. I. 403 1.2I Howitzer, 1.30 554 1.76 Wt-, 23 *03 2. 685 2,29 2.30 801 2.8 3. 903 3.29 3.30 997 3,75 4. 1083 4.21 5 - I235 5.o8 6. I,367 5-94 7. I484 6.75 8. 1589 7.52 9. I684 8.26 IO, I 770 9,.30 205.59 3.25- SPHERICAL I. 381 I.I5 CASE. I.30 536 1.7 2. 674 2.23 Wt. —30-75 2,30 799 2,74 3 - 9I3 3.24 e.=4365 3.30 IOI6 3.71 I.V.I I IO 4- III3 4, 17 5. I288 5.07 6. 1I442 5.93 7 - I58 6.75 8. 1704 7-53!9- I8I8 8.2 9 1o0. 922 9.02 _ I 5. 2344 I2o03'30~ 4-11 24 Pdr. Siege 6. SHOT. I. 704 Gun. 1.30 934 Wt.:24.3 lbs. 2. 1124 c.=4 167 230 1283 3 I.V. —:i68So. 14"~6 6o 30 1555 4. 5672 4 1i874 6. 2046 7- 2195 8, 2329 9. 2450 I IIO. 2562 520() RANGES. Ordnance. Charge. Projectile evation. Range. Time. Remarks. / Yards. RSeconds 24 Pdr. Siege Lbs. SPHERICAL..30 418.87 Gun. 6 CASE. I. 707 I.65 1. 30 930 2.37 Wt.=22.46 2. I114 3.03 C.-=3860 2, 30 271 3.66 3. I408 4.26 I.V.=I7 —1 5 3. 30 1529 4.33 4. I 637 5.38 5.- 828 6.43 6. 1993 7.43 7- 2I34 8.36 8. ]226 I 9.26 9. 2377 10. I3 Io. 2480 10o.97 -30 419.88 6 | SHELL. I. 684 I.64 I. 30 863 2.34 Wt. —= 7.5 lbs. 2. 1043 2.98 (-=300~~7 2. 30 II76 3.58 3- I292 4.15 |V. —I782 3. 30 13 I393 4.68 4- I484 5.20 5- I 654 6. I 8 6. I777 7.09 7- I895 7-94 8. 1997 8.73.9. Io0..30 402 32 Pdr. Sea 8 SHOT. I. 699 Coast Gun. I. 30 935 Wt.=32.3 lbs. 2. 1135 2. 30 1306 [4' 1457 I.V. —I640 3 o 3. 30 I59I 4- 1712 5- 1927 6. 2112 7- 2274 8. 2419 9- 2549 ___i 10~.' 2664.30 41 3.86 8 SPHERICAL I. 709 1.64 CASE. I. 30 943 2-36 2. 1140 3.04 Wt.=I3~-75 2. 30 I308 3.68 3- I454 4.29 W.=4365 3. 30 I584 4.87 I. V.=16.75 4. 1702 5.44 5 1910i 6.52 6. 2089 7-54 7. 2246 8.5I 8. 2387 9.43 9. 2511 I0.33 IO. |566 I I.so RANGES. 521 Kind of Ordnance. Charge. Projectile. Elevation. Range. Time. Remarks. 0 / Yards. Seconds 32 Pdr. Sea Lbs. SHELL. 30 4IO.86 Coast Gun. 8. I. 693 I.65 Wt.=23.3 lbs. I. 30 901 2.35 c.-33o7 2. I o69 3. 2. 30 1i213 3.6 -V'=I754' 3V. I 337 4-I9 3. 30 1443 4,74/ 4- I 542 5.28 5. I71I 6.28 6. I857 7.24 7. 1984 8.14 8. 2096 9. 9. 2I97 9.82 IO. -30 407 42 Pdr. Sea I0.5 SHOT. I. 712 Coast Gun. I. 30 960 Wt.=42.5 lbs. 2. II70 C —=5036 32. 30 1350 3. 1510 I.V.=I638 3. 30 1653 4. 1781 6. 2208 7. 2382 8. 2537 9. 2675 10. 2805.30 187.56 8 Inch Siege 4. SHELL. I. 350 I.I Howitzer. I. 30 498 1.63 Wt.:46.6 2. 623 2.14 C.=4I 61 2. 30 740 2.62 3. V.io6o 847 3.I 3 30 944 3.56 4. 0Io36 4.02 5. 1200 4.86 6. 1 346 5.7 7- I477 6.5I 8. 1I597 7.3 9. I704 8.o5 Io. 1805 8.8 12. I986 10.3.30 2I4.6 8 In.Sea Coast 6. SHELL. I. 397.17 Howitzer. I. 30 558 1.73 Wt —49-75 2. 700 2.27 C-=4442 2. 30 829 2.79'-V — 1 3. 946 3.3. 37 3 30 1053 379 4. 1153 4.27 5- I333 5.I9 6. 1489 6.07 7- 1630 6.9I 8. 1758 7.74 9. 1874 8.55 ID. 1 9~34 9-33 522 RANGES. Kind of Ch Ordnand of Charge. Projectile. Elevation. Range. Time. Remarks. 0 / Yards. Seconds Io Inch Sea Lbs. SHELL.. 30 3 313 [ 7 3 Coast Io I 593 I.45 Howitzer. Wt. —=Io.75 I 30 82I 2. I3 C.-=57 8 [6 2. I020 2.77 2. 30 1197 3.4 I.V.'-I420. 3. I 355 3.99 3. 30 I 500 4-57 4 I 1634 5I13 5- 1870 6.21 6. 2079 7.23 7. 2263 8.2 8. 2428 9I13 Final Angle 9. 2579 10.03 Velo- of I0. 2718 10,9 city. Fall..30 298 Feet. / 8 Inch I0. SHOT I. 549 Io65.. I 2 Rodman. I. 30 765 | Wt.=65 lbs. 2. ] 966 885- 2. 42'5893 2. 30 1127 C.=~5893 3. I283. 775. 4- 23 I.V =I350 3. 30 1428 -4 I558 695. 6. 19 5. I794 635, 8. 24 6. 2004 589. Io. 3i 7. 219I / 545. I2. 48 8. 2363 517~ 15. I0 9. 2599 490. 17. 34 Io. 2665 466. 20. 8 15. 3269 381. 20. 3746. 327. 30 3 I 8 If the gun is above Jo. SHOT, I. 582 the object, the anI. 30 807 gle offall must be. WtC6.s I' 3 ~ 8~?.increased by the Wt.=65 lbs )2. I005 angle of depres].=5893 2. 30 1182 sion correspond-3. 1342 ing to the range I. V.= 1400 3 and height of the 7- 30 1488 gun. 4. 1622 5. i865 6. 2077 7. 2267 8. 2441 9. 2599 IO0. 3 I2747 15- 3354 4 20. 3833.30 355.79 so. i SHELL. I. 628 1.52z I. 30 852 2.2I Wt.=51.5 2. 042 z.85 e.-4669 2. 30 I207 3 —7 3. 5354 4.u7 I.V.=I5I7 3. 30 J1487 4.65 4. I6o8 5.25 5. 1822 6.28 6. 2008 7.29 7- 2174 8.25 8. 2322 9.19 9. 2457 I0.I I0. 258I 10.97 I5- 3093 I5.1 I RA-NGES. 5 23 Ordnance. Charge. Projectile. Elevation. Range. Time. Remarks. 0 Yards. Seconds 8 inch Lbs. SHELL.' 669 1.58 Rodman. 10 2. Io88 2.95 Wt.=49.75 4 I1399 4.17 4. 1647 5.3 c.-=4442 5. 1855 6.36 I.V.-I-598 6. 2034 7,35 7- 2191 8.29 8. 2 2332 9.19 I 9. 2458 1o.o05 o. 2574 IO.87 Final Angle. 285 6 velo- of II 2680 11.65 it. Fall 12. 2779 12.4 city. Fall. _o Inc * SHT. ~ 30 272 Feet. 0 ro Inch I 5 SHOT. I. 51 1146. Rodman. I. 3o 724 I047. I. 8 Wt. —-I23.5 2. 9x6 968. C._702 8 2. 30 090I 905. 2. 30 3. I1251 853/ I.V-.==I75 3. 30 140I 808. 4- 3 4. I539 769. 5. 1793 735. 5. 44 6. 20I9 677. 7. 32 7. 2225 63I. 9. 23 8. 2414 593- II. 22 9. 2587 560. 13. 24 10, 2749 532. I5. 27 15. [ 3429 508. 17. 34 20. 39761 4I9..30 265.68 37210 SHELL. I. 504 I 33 I. 30 708 1.95 Wt —=IOI75 2. 886 2.56 0.-5786 2. 30 1048 3.15 I.V.:1284 33 10195 3.71 I.V.=I284 3. 30 1330 4.25/ 4. 1455 4-79 5. i680 5.83 6. I879 6.82 7 2057 7-78 8. 22I71 8.7I 9- 2363 9.6 Io. 2498 10.46 I I. 2621 I1.31 12. 2737 I2.I4 524 RANGES. Kind of' - ____________ -Final -Angle Ordnance. Charge. Projectile. Elevation. Range. Time. Velo- of city. Fall. ~ / Yards. Seconds Feet. O' IsInch Rod- Lbs. SHOT. I. 360 944' I. 7 man Gun, 40. 2. 684 877. 2. 14 Wt.=428 lbs. 3 976 822. 3. -30 C.-I0760. 4. I243 776 4. 49 5. 1490 736. 6. i4 I.V._Io28. 6. 1718 702. 7. 4 7- I93I 672. 9. 12 8. 2I29 646. I0. 49 9. 2314 622. I 2. 25 I0. 2489 603. I4- 4 1 5. 3225 525. 22. 34 20. 3787 475- 30, 51 30 253 40. SHELL. I. 482 I o48. I. 30 692 Wt. —344 lbs. 885 932. 2. 23 c.=8648,3 3. I230 845. 3 49 4. 534 778. 5- 22 I.V.-=I 2I 8. 5- I 8o6 724. 7. 6. 2053 679. 8. 44 7. /2280 641. I0. 34 8. 2488 609. I 2. 24 9. 2682 580. I4 20 I0. 2865 555' I6. I8 15. 3641 463. 26. 26 20. 4271 40o. 20. 26, 4322 4I I. 5s56.4 40. SHELL. 2. 10~9~ 2.7 3. I 3 69 3.92 Wt.-328 lbs 4. i686 5.I C.=8 I887. 5. I965 6.22 6. 2214 7.29 I. V.=I325. 7. 2439 8.35 8. 2644 9.37 9. 283I I0.3 6 I 0. 3003 II.3I 1 2. 3312 13.I3 I5. 3707 I 6. -20. 26 41I65 19.25 I. 406 I,12 40. SHELL. 2. /52 2.3 3..0o5 3 3.4 Wt.-3 I4 lbs 4. I 314 4-43 C-79I, 5- 55I 5'4 C.6= 79 1765 6.35 I.VI I Io. 7- 1963 7.29 8. 214I 8,18 9. 2309 9'~5 I o. 464 9.88 I 2. 2745 II49 5. 3105 13.69 RANGES. 5"5 Ordnand of Charge. Projectile. Elevation. Range. Time. Remarks. / Yards. Seconds 3 Inch Rifle Lbs. DYER SHELL..30 258.66 Ranges at WishGun. I. I. 489 1.29 ington Arsenal, t.=91bEGun. 489 I1. ~ 489 7I'.29 /March 8th, 1865. Wt.=g lbs. 1.30 700 1.91 C.=8 I67 2. - 892 2Y53 o Yards. 2.30 1070 3.12 3 1236. I.V.1= I232 23 3 I1234 3.7 4 1510. 33~ 1386 4,~5 ~5 1785. 3.*3 I38 4.25 10 2790. 4. 1530 4.8 5. 1794 5.87 6. 203I 6.9 7 2244 7.87 8. 2441 8.83 9. 2621 9.75 IO, 2788 10.67 12. 3II4 12.45 20. 3972 I7.88.30 259.66 3 In. Parrott I. SHELL. I. 494 -.3 Gun. 1.30 710 1.93 Wt.=Io lbs. 2. 909 2.54. —9075 2.30 1092 3.I4 3. 1262 3.72 I.V. —I232. 3.30 1422 4.29 4. I1573 4.85 5. I 85I 5.96 6. 2101 7.02 7.- 2328 8.04 8. 2536 9.04 9. 2729 I0.02 10. 2907 I1o.96 12. 32I2 12.7 __ __ 5 3558 I15.09.30~ 290.69 4~ In. Rifle 3.25 DYER SHELL. I 553 1.37 Gun. I.30 799 2.05;Wt.=z255 2. IOI7 2.69 2.30 1224 3.32' —IO491'4.I 49I 1414 3 394 I.V.=I303 3.30 I593 4.54. 4-. 1762 5.I4 5. 2071 6.3 6. 2354 7.42 7 - 2610 85 I 8. 2844 9-57 9. 306I i o.6 10. 3265 11-59 526 RANCES. Ordnance Charge. Projectile. Elevation. Range, Time. Remarks. _ / Yards. Seconds z4 Pdr. Gun Lbs. SHOT. I. 495 Rifled. 4-5 2. 929 Wt. —52z2 lbs. 3. 1317 C. —I2587 4, 1663 5. 1976'V —zsx5. 2266 7- 2530 8. 2777 9. 3007 10. 3221 12. 3611 _ _5. 4118 _. 497,.3 4.5 SHELL. 2. 925 2.5 3. 1300 3.7 Wt.=45.21bs. 4. 1629 4.9 C._=IO899 5. I927 6. 6. 2200 7. I.V.-=I224 7- 2449 8.s 8. 2682 9. I 9 2897 10.I I0. 3092 II. 52. I 3452 I2 8 _ _. 3918 I5.3 I. 5I3 32 Pdr. Gun 6. SHOT. 2. 96I Rifled. 3- I353 WVt.-6o.4 lbs. 4. I705 e.=I22z86.5 5. 2024 6. 2314 9I. 3061 50. 3276 12.'13665 __ ___ _5. 4170 I 482 1.28 6. SHELL. 2. 905 2.52 3. I274 3.7 W't. —55.5 lbs. 4. 1603 4.84 C.=_II289.7 6 I1902 5.94 6-'. 2175 I.V. —I205. 7. 2424 8~o03 8. 2657 9.03 9- 2872 IO. IO. 3067 I0.95 I 2. 3437 I z75 RANGES. 5 27 Ordnanc ge. Projecle. Elevation. Range. Time. rRemarks.._0 Yards. Seconds 30 Pdr. Par- Lbs. SHOT..30 289.09 rot Gun. 3.25 I. 557 I.37 XWt.=29.2 lbs. I. 30 808 2.03 C.z —3698. 2. 1043 2.69 2. 30 I264 3.34 I,V.=Iz293. 3- 147I 3-97 3. 30 I667 4-59 4. I854 5.2I 5- 220o 6.4I 6. 25I9 7.58 7- 28811 8-71 8. 3082 9.82 9. 3334 I 0.9 I0. 3568 I I.96.30 2-7.69 3.25 CASE. I. 554 I.37 I- 30 804 2.03 Wt.= —g.2 lbs. 2z. I39 2.69 2. 30 1259 3.33 C.-_I 3792 3. 1465 3.96 I.V.zIx289 3. 30 1662 4.58 4. 1849 5.2 5- 2I96 6.4 6. 2513 7.56 7. 2805 8.69 8. 3076 9.8 9- 3328 10.87 10. 3562 11.93.30 303.7 3.35 SHELL. I. 584 I.4 I. 30 843 2. I Wt. -z27,5 2. Io8 2.8 C.=I2z989. 30 1310 3,5 8.V —132 3. 1520 4.1 I. V.=I328 3. 30 1719 4.7 4. I1907 5.3 5 2254 6.5 6..2573 7.7 7- 2862 8.8 8. 3130 9.9 9. 3379 II. I0. 3610 I2..30 3I3 3-25 SHELL. I. 603 I. 30 867 Wt.=26.5 2. IIII C.-IZ251I7 2. 30 1338 3. 1 -551 I. V.=I353 3. 3 1752 4. I941 5. "2293 6. 2606 7- 2898 8. 3I62 9. 3408! 1J. 3636 5') RANGSES. Kind of Ordnance. Charge. Projectile. Elevation. Range. Time~' Remarks. 0 / Yards. Seconds 42 Pdr. Gun Lbs. JAMES SHOT..30 305 Rifled. 8. I. 587 Wt.=84 lbs. I30 85 I c.-1428 35 2 2,30 1330 I.V. JA 32S 3. 1549 3.30 3756 4. i953 5. 2322 6. 2660 7- 2973 8. 3266 9, 3543 Io. 3803 ~30 343 -.76 8. JAMES SHELL. I. 650 1.49 1.30 930 2.25 Wt.z-68 lbs. 2. 1187 2.91I e.-II563 2.30 1422 3,59 3- 642 4.26 ~I.V.z420 3.30 1848 4.92 4. 2041 5.56 5. 2396 6.8x 6. 2718 8.02 7. 30oi3 9.21 8 3283 o10.35 9 3535 11.46 10. 377I 12-57 RANGES. 529 Ordnance. ]k Charge.| Projectile. Elevation.| Range. Time. Remarks. / Yards, Seconds looPdr. Par- Lbs. - SHOT. I. 515 rot Gun. Io. 2. 986 Wt._-99.5 lbs. 3, 1420 c.zz20240 4. 1824] 5. 2200 I.V.~Z=1222 6. 2554 7. 2888 8. 3205 9. 3506 10. i 3792 I5' 5062 20. 6127 25. 7068 30. 7906 I. 486.27 I0. SHELL, 2. 937 2.52 3. 1356 3-74 Wt.=-iox lbs. 4. I745 4-94 C.-_-20545 5 21 6.10 II C 2454 7.26 I V.xiI88 7. 2780 8.4 8. 3089 9.52 9. 3384 Io.63 10. 3664 11.72 15. 4932 17.28 20. 5918 22. I 25. 6899 27.55 30. 7740 33,03 I, 599 10, SHOT. 2. II26 3. 1I 594 Wt.-8o lbs. 4. 201 5 e. — i6273 5, 2401 V —33 6. 275 I. V.=I335 I7. 3077 8. 3378 9 3660 10. 3924i 15. 5022 20. 5830 250 64'5 6 __30. 683.33 327.74 8. DYER SHELL. 67 I.46 I. 30 9O0 1 2.I7 Wt.=6I. 5! 2. 1153 2.86 2. 30 1388 3.53 C.=I25-IO.2 ~3. 6o6 4.19 I.V.=-I384 3- 30 I8Io 4.83 4.'2003 547 5 2359 6.71 6. 2682 7-91 7- 2976 9.07 8. 3245 10.20 9- 3494 II.33 10. 3726 1'42 530 RANGES. The following ranges are determined by practice, and lie in the plane of the platform on which the bed stands. Kind of Ordnance. Charge. Projectile. Elevation.l Range. Time. Remarks. o0 Yards, Seconds 8 Inch Siege lbs. oz. SHELL. 45. t 360 8.o Ranges obtainMortar. o. 8 Wt.=46 lbs.. 703 I2.5 ed from experi(Model1861.) o. I2 I so82 I5.o ments made near 1. 0 1' 4Ix2 17.0 Petersburgh,Va., I. 4 " I74I 18,5 by the ISt Conn. I. 8 9 I985 2o.o Artillery, in Sept. I. I2 " 2225 21.0'64. 2. 0 Old Model. Model I86I. Io Inch Siege o. 8 SHELL. 89 6.4 I23 Mortar.. Wt.=golbs. 245 10.4 276 6.9 I, 8 85 14.2 522 2. 0 " 1122 17.2 774 11.5 2, 8 " I4Io I8.4 I I44 4.6 3. 0 c 676 9.8 I466 17.5 3 5 c 1848 20.9 I81I 4. 0 c 2064 21.9 2028 8 Inch Siege o. 4 SHELL. 31I4 300 Howitzer. o. 8 Wt.=46 lbs. " 620zo 553 As a Mortar. o. 12 I 1I82 I. 0 I440 1 332 I. 14 4 I925 I695 TABLES OF FIRE. 1 RANGES WITH SEA-COAST 13 INCH MORTARS, 20~ ELEVATION. R Mean time of CHARGE:. Flight. Least Range. Greatest Range. Mean Range. Lbs. Seconds. Yards. Yards. Yards. 4 8 840 877 869 6 9.5 I209 1317 I263 8 1 Ix.66 i653 1840 1744 10 I2.50 2010 2128 2066 I2 14.25 2369 2688 2528 14 1 5.25 2664 2780 2722 RANGES WITH 13 INCH MORTARS, AT 450 ELEVATION. 13 INCH MORTAR. Powder. Shell. Elevation. Range. Lbs. Lbs. Yards. 20 200 450 4325 RANGES WITH I3 INCH MORTARS AT 450 ELEVATION. Charge. Flight. Fuze. Range. Lbs. oz. Seconds. Inches. Ioths. Yards. 7 21.4 4 32 2190 7 8 22.4 4 4 2346 8 23.2 4 6 2480 8 8 i 23.8 4 7y 2600 9 24.4 4 8~ 2734 9 8 24.9 4 9a 2853 Io 25.4 5 I 2958 Io 8 25.9 5 I 3026 II 26.3 5 25 3150 II 8 26.7 5 3L 3246 12 27.0 5 4' 3327 12 8 27.4 5 4 3404 I3 27-7 5 5~ 3470 13 8 28.0 5 6 3552 14 28.3 5 66 3617 14 8 28.5 5 7 3681 IS 29.0 5 8 3739 5 8 29.1 5 84 3797 x6 29.2 5 8~ 3849 I6 8 29.4 5 8j 3901 17 29.6 5 9 3949 17 8 29.8 5 91 3997 x8 29.8 35 9 4040 i8 8 30.0 6 0' 4085 I9- 30.2 6 o} 4123 19 8 30.3 6 01 4I60 20 30.5 6 I 4200 .58392 RANGES. Table showing the angles of depression of an object for different distances and heights of a gun above the water. HEIGHT. 1 1 I Foot. 2 Feet. 4 Feet. 8 Feet. I6 Feet. 32 Feet. 64 Feet. 96 Feet. Yards. o / o / o o / o / o / o / o / 200 5-7 1 I,5 23- 45,8 I 31.6 3 3-2 6 5-5 9 5,5 250 4.6 9,2 18.3 36.7 I 13.3 2 26.6 4 53- 7 17.6 300 3.8 7.6 15.3 30,6 I I,I 2 2.2 4 4- 6 5.4 350 3 3 6.5 I3.1 26.2 52.4 I 44.7 3 29-4 5 13.5 400 2.9 5.7 I I.4 22.9 45.8 I 3.6 3 3.2 4 34.5 450 2.5 5. 10o,2 20.4 40.7 I 21.5 2 42.8 4 4. 500 2.3 4.6 9.I I8.3 36.7 I 13-3 2 26.6 3 39.7 550 2 1 4.2 8.3 16.7 33-3 I 6.6 2 13.3 3 19.8 600 1.9 3.8 7.6 15 3 30.6 I I.1 2 2.2 3 3-3 650 1.7 3-5 7- 14.1 28.2 56.4 I 52.8 2 49.I 700 1.6 3.3 6,5 13.1 26.2 52.4 I 44-7 2 37750 1.5 3. 6.I 12.2 24.4 48.9 I 37-7 2 26.6 800 1.4 2.8 5.7 II.4 22.9 45.8 I 3 I.7 2 17-4 850 1.3 2.7 5.4 Io.8 21.6 43.5 I 26.3 2 9.4 9oo 1,3 2.5 5.1 I0.2 20.4 40.7 I 21.5 2 2.2 950 1.2 2.4 4,8 9.6 19-3 38,6 I I7-2 I 55.8 I000 1.I 2.3 4.6 9.2 I8.3 36.7 I 13.3 I 50. II00 I. 2.I 4.2 8.3 I6.7 33-3 I 6.7 I 40. 1200.9 I.9 3.8 7.6 1553 30.6 I I. II 31.7 1300.9 i.8 3.5 7 14. I 28.2 56.4 I 24.6 1400.8 1.6 3-3 6.5 13-I 26.2 52.4 I I 8,6 5oo00.8 1.5 3- 6, I 12.2 24.4 48.9 I 13.3 I600.7 1.4 2.9 5-7 11.4 22.9 45-8 I 8.7 1700.7 1.3 2'7 5-4 Io.8 21.6 43-.I 4-7 18oo.6 I,3 2,5 5-1 1o.2 20.4 40.7 I 1.1 1900.6 I.2 2,4 4.8 9.6 19-3 38.6 57.9 2000.6 x1.2 2.3 4.6 9.2 18.3 36.7 55. 2100.5 I.I 2.2 4.3 8.7 17-5 34.9 52.4 2200.5 1. 2. I 4.2 8.4 I6.7 33-3 50. 2300.5 I. 2. 4. 7-9 I5.9 3I-9 47.8 2400.5 I. 1.9 3.8 7.6 15-3 30.6 45.8 2500.4.9 I.8 3.6 7-3 I4-7 29.3 443000'4.8 1'5 3. 6. I 12.2 24-4 36.7 3500.3.7 1.3 2.6 5.2 10.4 21. 31I4 4000.3,6 1.1 2.3 4.6 9.2 18.3 27,5 4500.3 5 I. 2. 4. I 8.I 16.3 24,4 5000.2.5.9 1.8 3.7 7-3 14.7 22. When the height of the piece above the water or horizontal plane is known, the angle of depression for different distances can be found by using the foregoing table, Find the angle for any height not given in the table, as follows: divide the given height into parts, which are found in the table, using the largest number possible; and add the angles corresponding to those parts, for the required distance. Example: required the angle for distance Iooo yards and height 23 feet. 23 feet gives the parts i6, 4. 2, & I. i the sum of the angles for these heights is I8.3/+4.6/+2,.3"+I-/=.26,3/, In using the quadrant, or giving the elevation from the horizontal plane of the piece, if the picce is higher than the object fired at, the angle of depression should be deducted from the "elevation" in the table of ranges. Example: the Io inch Columbiad at 6~ gives about 2000 yards range; if the piece is 32 ft. above the object the angle of depression is I8.3' and the quadrant should be set at 5 I 4I.7/. VELOCITIES. r5,3, Remaining velocities for Sea Coast Projectiles, calculated by Capt. Stockton, Ord. Dept. by formula on page 417. Distance for Calibre. Initial Velocity. which remaining Remaining Loss of Velovelocity is cal- Velocity. city. culated. Feet. Feet, Feet. Feet. I5 inch 1200 1500 xo66 134 Shot. c 3000 961 239 6000 773 427 I5oo 1 0500 I315 I85 "c 3000 1 65 335 6oo3 929 571 13 inch 1200 o 500 1045 5 5 Shot. "c 3000 924 276 "4 600oo 695 505 1 5o0 1500 1293 207 3o000 I18 382 "cc 6000 865 635 io inch 1200 1500 1007 I93 Shot. 4( 3000 854 346 c 600oo 632 568 I 500 1500 1251 249 c" 30,00 0I32 468 "4 6000 741 753 S inch 1200 1 500 964 236 Shot. c" 3000 792 408 &4 6o00 550 650o 1500 1500 II77 323 4c 3000 948 552 c" 6ooo 643 857 I2 inch Rifle 1200 1500 1154 46. Shot. "9 3000 I 0 9o. (c.-34920.) " 6000 1 028 72. Io inch Rifle 1500 2I 25 75 Shot. 3000 Io56 I44. (.=3 I o 56.) 6000 939 26 8 inch Rifle 1500 I15 85 Shot. 3000 I048 52 (c.=I9636.) 6000 927 273 534- RANGES. RESULTS OF EXPERIMENTAL FIRING with I s-inch Columbiad, from barbette platform No. 20o of Fort Monroe, Va., made between Oct. 24th, 1865, and Nov. ioth, I865, to determine the penetration of a Solid Shot and Shell into a Sand target (well rammed) 30 feet thick, I5 feet high, and fifteen feet front, located 400 yards from the Gun. 7s 0 Lbs. o F. In. Ft. n. F. In. I SO ~ 3o 6 5 2 o Ix5 8 Solid Shot. 2 CC 5 I 2o 6 IO 6 /I" Struck ground before enterChassis and rebounded 3marks. 3 3 6 2 7 I0 4 30y8 4 S o i 5 Lbs. 0 3 Ft. In. Ft. n. Ft. In Chassis rails sanded, I 50 30 657 4 8 o 158 o Solid Shot. 2 o I0 5 o 2 6 Io 6 cc 4 Struck ground before enter of 3 010 IO 5 4 80o 200 " "L'< ing target. 4 " o05 74 8o ]6o " Chassis and rebounded 3 4'0 I75 5 0 1 3 0 Shell. inches. I ~30 5 6 6 o Shell 2 O 30 4 4 3 o 3 ~ 30 65 z 7 I0 9 " 4 " 030 8 7 6 9o 8 "7 5 o 0 30 3 0 10 Chassis rails sanded, I 45 o 23 5 6 o II0 Solid Shot. 2 0 8 6 3 o I0 1 " " Carriage struck c-heurter of 3 8 67 8 0 "4 Chassis cand rebounded I6 4 L 0 655 j 7 0 10' " inch, Carriage struck c5 0 15 6 7 6 " " heurter of Chassis a nd re6 o 8 5 6 6o " " bounded 0 inches, 30 9 3o o Shell. Chassis rails sanded Struck 2 3 030 4 7 4 3 O ~ e "e 3 030 1 5 0 906 i get. 4 " o 30 46 6 o 7 I 5 o 3 4 8 7 o 0 12 6 6 " o30 476 3 70~ 6 I 40 23 6 inches,0 Average weight of Solid Shot. Struck ground before enter2 "' o 8 63 40 120 " " ingtarget. 3 c~ 0 8 602 I0 126 " " 4 " o 8 6 I 6 o 17 " " I z 0 30 2 9 3 0 6 0 Shell. Chassis rails sanded. Struck 2 02 z 34 o3 I ground before entering tar3 " 030 30 50 96 " get. 4" o 23 36 40 8o 5 o 023 36 4 o 66 " 6 o 23 37 7o 70 Reference of base of Target-o ft. o inch. Reference of axis of trunnions of Guo -30 ft. 9 inches, Average weight of Solid Shot=434 lbs., ditto of Shell= —zo lbs. PENETRATION IN EARTH. 535 RESULTS OF EXPERIMENTS MADE AT WEST POINT, BY CAPTAIN BENET, ORDNANCE Corps, upon the Penetration and Explosive Effects of the Projectiles of the Parrot Gun, into a mixture of sand and clay, free from gravel, and compactly rammed. The sides were confined by a strong vertical boarding. The front and rear had the natural slope. Distance, 24 yards. Projectile, Powder, Penetrat'n CRATER. GUN. lbs. lbs. Feet. Diam. Ft. Depth. Ft. zo Pdr. - 3 9 -Greatest Penetrat'n 2zoPdr. - 2 8 -- - do. 2o Pdr. - 2 6 4 & 8 I & 2 Per'nShell, Av. Pen 30 Pdr. 25 - 31 to 4 44 to I34 10 to 1z2 2 to 3 Percussion Shells. 30 Pdr. 294 3 4 to 4 Io Average Penetration Ioo Pdr. 80oto 6 10 14 Hazwell'sNo.5 &7p 0oo Pdr. 8s I 2. 1,5- do. No. 7. oo00 Pdr. 8I It a - 1 -- iMammouth powder. 0oo Pdr. 32 12 o - - Hazwell's No. 7 do. 1oo Pdr. 1o O 522 to 144 124 Hazwell'sNo. 5 do. zoo Pdr. I 5 I8 I2t to 18 200 Pdr. I 46 I6 toI8 8 o t 2to 17 I x to 5 Experiments were also been made for penetration with the same guns into a but of well-rammed gravel, at a distance of I,ooo yards, with the following results, viz. For the solid projectiles of the 2o-pounder and 3o-pounder guns, tLh average penetration was three feet. For the solid projectiles of the xoo-pounder gun, weighing eighty pounds, the average penetration was seven feet. For the solid projectiles of the zoo-pounder gun, the average penetration was eight feet. 536 PENETRATION OF RIFLE BULLETS. RESULTS OF EXPERIMENTS ON THE PENETRATION OF RIFLE BULLETS INTO VARIOUS SUBSTANCES. See Professional Papers of the Corps of Royal Engineers, Vol. VII., New Series. The arms used were the Enfield Rife and the Lancaster Rifled Carbine. RANGE With Lancaster Rifle, the mean penetration into a INches. 20 Yards. parapet of light, sandy soil, rammed lightly, was.. 15. With Enfield Rifle, circumstances the sahme. IS. Lancaster Rifle, mean penetration into solid oak.... 2.8 Enfield " " " " i 2.75 Lancaster Rifle, mean penetration into two thicknesses of three inch oak........... Enfield Rifle, mean penetration into two thicknesses of three inch oak........................... 3.58 Enfield Rifle, penetration into solid pine, with the grain 9.8 3 Lancaster Rifle, penetration into sand bags, filled with light sandy earth, and formed as a parapet....... All stopped Enfield Rifle, one bullet passed through a stretcher. Lancaster Rifle, penetration into a sap roller four feet exterior diameter, 2.5 feet interior diameter, nine INCHES. inches thickness, fascine stuffing.............. Enfield Rifle, same penetration as Lancaster Rifle. Lancaster Rifle, penetration into fascines, nine inches diameter, of green wood, backed by earth. Through the fascines, and into the earth................ 7 Enfield Rifle, same circumstances.............. 8. With gabions of both brushwood and sheet iron, filled fresh with light sandy earth, the bullets of neither arm passed through. 50 Yards. It required a rope mantelet, like those used at the siege of Sebastapol, consisting of three vertical and two horizontal layers of four and a half inch rope, weighing twenty-seven and a half pounds to the square foot, to give full protection against the bullets of each arm. COST OF GUNS. 5 37 COST OF GUNS.-(HOLLEY'S ORD. AND ARMOR.) Name of Gun. Material. Bore. Weght Cost per Total'__ _ _ _ ______ pound. Cost. Inches. Lbs. Cts. $ Cts. 13.3 inch Armstrong. Wrought iron coils in hoops.............. 13-3 51351 37- 19000.00 1o0 inch do.. Do. I0.5 26880 33.6 9000.00 IIo pdr. do.. Do. 7. 9I84 23-9 2195-75 Horsfall gun........ Wrought iron forged solid 13. 53846 23.2 12000Izooo.oo00 Alfred, gun....... Wrought iron forged hollow.. I. 24094 20.7 5000.00 Krupp's 15 inch gun. Cast Steel forged solid.. 5. 33600 87.5 29400.00 Krupp's 9 inch gun.. Do. 9. 9.8000 5 65 I O 10.00 Bessemer forging..... Do. 7 to 8 11200 I3.0 1466.00 Blakely I2 inch gun.. Cast Steel hooped with steel........... I2. 40000 87.5 35000.00 Blakely I I inch gun.. Do. II. 35000 78.5 27500.00 Blakely Io inch gun.. Do. Io. 30000 53.3 17500.00 Blakely I20o pdr gun. Do. 7. 9600 6z.5 6000.00 Whitworth. I20 pdr. gun............. Do. 7- 13440 37.2 5000.00 Parrott Ioo pdr. gun. Cast Iron hooped with 97100 2.4 1300,00 wrought iron........ 4 Parrott 8.inch gun... Do. 8. I6300 14.I 2200.00 Parrottso inch gun... Do. 0. 26500 17.0 4700.00 Rodman 15 inch.... Cast Iron-Cast hollow. I4900 13.2 6500.00 Rodman Io inch.... Do. I. 5059 1.0 I665.oo00 Rodman 8 inch..... Do. 8. 8465 oI.8 Iooo.oo Ames gun.......... Wrought Iron, built up. 7 9 I19400.00 3 inch field gun.....Wrought Iron, solid.... 820 550 450.00 NOTE. —The cost of bronze field guns is about fifteen cents per pound more than the market price of copper. A PPE ND T X. APPENDIX. IT is proposed in this Appendix to give a short description of some of the most noted modern cannon and projectiles, and in doing so the author has freely consulted the valuable work of Mr. Holley, on Ordnance and Armor. 1. Armstrong gun. Armstrong guns are of two kinds,breech-loaders and muzzle-loaders. In consequence of not possessing the requisite strength and endurance, the breech-loading apparatus of the Armstrong guns is now only applied to the smaller calibres. Construction of breech-loaders. The body of the piece is made by welding together several wrought-iron tubes at their ends; each tube is fiom two to three feet long, and is form.ed by twisting a square bar of iron around a mandrel and welding the edges together. Thus far the piece resembles the barrel of a fowling-piece. To strengthen the part in rear of the trunnions, it is enveloped with two additional thicknesses, or tubes. The outer tube, like the in. ner one, consists of spiral coils; but the intermediate tube is formed of an iron slab, bent into a circular shape and welded at the edges. The reason for this distinction is, that the intermediate layer has chiefly to Sustain the pressure on the bottom of the bore, while the other layers are formed to resist the tangential strain. Fig. 155. Breech. The breech is closed with a vent-piece (b), fig. 155, which is slipped with the hand into a slot cut in the breech of the piece, and held in its place by a breech-screw (a), which supports it fiom behind. This screw is made in the form of a tube, so that its hollow forms a part of the bore prolonged, when the vent-piece is with 54'2 APPENDIX. drawn. The object of this hollow is to allow the charge to be passed into the chamber. Bore. The bore of the field-gun, which is represented in the dlawing, is three inches in diameter, and is rifled with thirty-four narrow grooves. Twist, one turn in 9 feet. The diameter of the chamber is one-eighth of an inch larger than that of the bore. Vent. The vent is formed in the breech-piece in order that when it becomes enlarged it may be easily replaced. For this purpose, spare vent-pieces are carried with each battery. The diameter of the vent is one-half an inch, and is primed by filling it with a small paper cartridge of fine powder, which is ignited by an ordinary friction-tube. Juzzle-loading. The most approved method of making the large muzzle-loading Armstrong guns, as practised at the Royal Gun Factory at Woolwich Arsenal in 1864, is shown in fig. 156.* Fig. 156. The barrel, or part surrounding the bore, is made solid of steel tempered in oil, by which its brittleness is not only diminished, but its tenacity is increased. That part of the barrel at and in rear of the trunnions is enveloped by three layers of wrought-iron tubes. These tubes are not joined at their ends by welding, as in the breech-loading guns of this system, but are hooked on to each other by a system of shoulders and recesses, as shown at a a in the accomFraser guni. This mode of manufacture has been somewhat changed at the suggestion of Mr. Fraser, Manager and Assistant Inspector of Machinery at the Woolwich Arsenal, and the guns now made at that establishment are known as Fraser guns, but in fact are nothing more than modified Armstrong guns. The modifications consist in reducing the number of coils; using a cheaper iron for the outer coils; shrinking on of the outer coils and trunnion piece together; and an improved arrangement of shoulders and recesses to prevent separation of the parts. It is understood that while these guns have nearly, if not quite, the strength of the Armstrong guns proper, their cost has been reduced from ~100 per ton to ~40 per ton for the coiled inner tube, and to ~55 per ton for the solid steel inner tube,-a cost per pound not much exceeding that of cast-iron guns in this country. Three sizes of these guns are now being made, viz.: 7-inch, or 115-pdr.; 8-inch, or 180-pdr., and 9-inch, or 250-pdr.; and to these will shortly be added a 10-inch, or 350-pdr., and a 12-inch, or 500-pdr. It is stated that guns of this system have undergone very severe tests. and that they are now being made in large numbers. ARMSTRONG GUN. 543 panying figure. When one end of a tube is expanded by heat, the shoulders are slipped over each other, and the contraction which afterwards takes place in cooling, causes them to fit into the corresponding recesses. There are also projections fitting into corresponding recesses, as at b b, which serve to prevent the tubes from slipping within each other. The tube which immediately surrounds the barrel opposite to the seat of the charge is called the breechpiece. It is not made of spiral bars as the other tubes are, but it is formed with its fibres and welds running longitudinally so as to resist the recoil of the barrel against the head of the breech-plug which is screwed into the breech-piece. The object of making the breechplug separately is to insure a better quality of iron than would usually be at the bottom of the breech-piece if made solid. Mr. Anderson recommends that the tubes next to the barrel have a tension of about 6 tons to the inch, in which state they are in a condition to bear an enlargement of.004 of their diameter without going beyond their limit of elasticity; a little more tension than this should be given to the next layer of tubes, while the outer layer should have a tension of 8 tons per inch. The Armstrong gun is formed very strong to resist tangential strains; and in consequence of the great ductility of the wroughtiron used for the tubes, this gun is not liable to burst without previously showing considerable enlargement. It is stated that of 3,000 guns built on this principle, not one has burst explosively. The number of grooves of the muzzle-loaders varies from 3 to 10, and the twist varies from one turn in 30 to one turn in 38 calibres. Dimensions and Weight of the Armstrong Guns of the. latest Elswich Patterns. Name of Gun. =0 co D o Inch. Inch. Inch. Inch. Inch. Lbs. Lbs. 12-pdr. Breech-Loader....... 83. 73.5 3. 9.75 5.75 918 12-pdr. Muzzle-Loader....... 76. 67.75 3. 10.9 5.6 996 60 25-pdr. Breech-Loader....... 96. 93. 3.75 12.75 6. 1,882 123 40-pdr. Breech-Loader.......121. 121 106.5 4.75 16.4 7.75 3,696 392 70-pdr. Muzzle-Loader....... 126.5 103. 6.4 25.3 12.4 9,016 548 150-pdr. Muzzle-Loader....... 129.75 102.25 8.5 31. 15.4 14,896 504 300-pdr. Muzzle-Loader...... 124. 10. 38.3 19. 26,880 600-pdr. Muzzle-Loader....... 183. 145.25 13.3 51.5 21.5 51,296 952 544 APPENDIX. Armstrong' guns are proved by firing them twice with service chaige:of powder and shot, and three times with service shot and a charge of po'wder equal to one-sixth of the weight of the service shot. The service charges do not vary much fonom one-seventh to one-eighth of the weight of the projectile. Rijling. The muzzle-loading Armstrong guns proper are rifled to "center" the projectile by what is known as the shunt system.* In this system the grooves are considerably wider than the buttons on the projectile, except near the bottom of the bore, where they taper down to the ordinary width. That part, or side, of the groove passed over by the projectile in going down the bore, is made deep enough to admit the buttons freely. The other side is so shallow as to press against the ends of the buttons as the projectile comes out, and thereby force its center towards the center of the bore. The changing, or "shunting" firom one side of the grooves to the other, takes place at the seat of the charge, and follows from the narrowing of the grooves, and from an inclined plane which leads fi-om the deep to the shallow side of the groove. Fig. 156 (a). Diagram A shows the position of the button in the deep part of the groove when entering the bore. C shows the manner of shunting it to the shallow side; a is the point at which the inclined plane commences. B shows the button on the driving or shallow side. 2. Whitworth gull. The Whitworth guns are made of a substance called "homogeneous iron," a species of low steel, which is said to be made by melting short bars of Swedish iron and adding a small quantity of carbonaceous matter, after which it is cast into round ingots. The smaller Whitworth guns are forged solid; the larger are built up with coils or hoops, after the manner shown in fig. 157. In the Armstrong guns the coils are shrunk on by the aid of heat; in the Whitworth guns the hoops are forced on by hydraulic * The Fraser, or " Woolwich guns," it is said, are rifled on the French button system as modified by Captain Palliser. The twist of the grooves is increasing with a view to diminish the strain on the breech of the gun, and to increase the accuracy of fire. WHITWORTII GUN. 545 -------------- -- - Fig. 157. pressure, and for this purpose they are made with a slight taper and with the design to secure initial tension. The ends of the hoops are joined by screw-threads. The hoops are first cast hollow and then hammered out over a steel mandrel, or rolled out in a machine like that used for forming wheel-tire. Before receiving their final finish, they are subject to an annealing process for some three or four weeks, which makes the metal very ductile, but, at the same time, slightly impairs its tenacity. The breech-pin is made with offsets in such a way as to screw into the end of the barrel and the next two surrounding hoops. The breech in the case of the large guns is hooped with a harder and higher steel than that used for the barrel. The 70-pdr. gun has one hoop; the 120-pdr. proposed by Mr. Whitworth was to have four tiers of hoops. The cross-section of the bore of the Whitworth guns is a hexagon with rounded corners. The twist is very rapid, and the projectiles are made very long. Dimensions, &c., of Whitworth Guns. Diam. of Twist. Weight Weight Bore across Length. Weight. Inches for of ote flats. e one turn. Powder. Projectile. Inches.. Inches. Lbs: Lbs. Lbs. 120-pounder........ 6.4 144 16,000 130 27. 1.51 70-pounder....... 5. 118 8,582 100 13. 81 12-pounder........ 2.75 104 1,092 55 1.75 12 The proof consists in firing once with a service charge, with the powder increased one-fourth-and once with a service charge of powder and a six-calibre projectile. 3. Blakely gul. The most approved pattern of the Blakely gun combines in its construction the principles of " initial tension" and "6 varying elasticity," the object of which is to bring the strength of all the metal of the piece into simultaneous play, to resist explosion. (See page 150.) 35 546 APPENDIX. Fig. 158 represents a 9-inch Blakely gun of this kind. Fig. 158. The inner tube, or barrel, is made of low steel, having considerable but not quite enough elasticity. The next tube is made of high steel with less elasticity, and is shrunk on to the barrel with just sufficient tension to compensate for the insufficient difference of elasticity between the two tubes. The outer cast-iron jacket, to which the trunnions are attached, is the least elastic of all, and.is put on with only the shrinkage attained by warming it over a fire. The steel tubes are cast hollow and hammered over steel mandrels, under steam hammers; by this process they are elongated about 130 per cent., at the same time the tenacity of the metal is increased. All the steel parts are annealed. Captain Blakely uses other combinations of these metals, the simplest of which is a cast-iron gun with hoops of steel surrounding the reinforce. He objects to the use of wrought-iron on account of its tenacity to stretch permanently. Blakely guns are rifled with onesided grooves, and are fired with expanding projectiles. _Dimensions, &c., of -Blakely All Steel Guns. Diam. Length Number Weight Weight Gun. Weight. of of of Twist. of of Bore. Bore. Grooves. Projectile. Powder. 1 turn in Lbs. Inches. Inches. Calibres. Lbs. Lbs. 100-pdr......... 8,000 6.4 96 8 48 100 10 120-pdr...... 9,000 7. 100 8 48 120 12 200-pdr.......... 17,000 8. 145 12 48 200 20 250-pdr.......... 24,000 9. do. 12 48 250 25 350-pdr. 30,000 10. do. 15 48 350 35 350-pdr.......... 35,000 11. do. 12 36 550 55 700-pdr... 40,000 12. do. 12 36 700 70 PALLISER GUN. 547 4. Palliser gun. Captain Palliser, of the British service, describes his manner of making a gun to consist in introducing into a cast-iron gun a barrel or hollow cylinder of coiled wrought-iron, of such thickness in proportion to its calibre, that the residual strain borne by the tube shall have a relation to the strain it transmits to the surrounding cast-iron, which shall be most suitably proportioned to their respective elasticities. The precise proportions will depend on various circumstances, viz.: the excessive expansion of wrought-iron due to heat, also the greater range between the limits of elasticity and rupture of this mnetal, and that the cast-iron will have to do nearly all the longitudinal work. By varying the thickness of the tube, the transmitted strains can be regulated with the greatest nicety. The mechanical method, says Captain Palliser, by which I propose to insert the tube, is by making it very slightly taper, and placing it in the gun, the bore of which is tapered correspondingly; as soon as the tube comes in contact with the gun throughout its length, a screw washer around the muzzle will screw it home into its place. See fig. 159. Fig. 159. Since the amount of taper, as well as the distance the tube is driven by the washer, is known, and the increment or decrement in cast or wrought-iron due to any pressure is also known, we shall in this manner be able to measure most accurately the strain placed on the cast-iron outer gun. In the larger guns Captain Palliser proposes to use two or more concentric tubes. In the very largest guns he proposes three tubes, the inner one to be of the softest and most ductile wrought-iron; the next may be of a stronger and harsher nature; the third of steel for some distance in front of the chamber. Old smooth-bored guns have been reamed out and strengthened on Captain Palliser's plan, and have shown remarkable strength. The guns tested were chiefly 68-pounders. A 9-inch gun has lately 548 APPENDIX. been tested with severe charges, some as high as 45 pounds powder and 250 pounds projectile. 5. Parsons gun. The principle upon which Mr. Parsons makes his gun would seem to be similar to that of Captain Palliser's, i. e., by varying elasticity. As applied to strengthening a 68-pounder cast-iron gun, his method consists of boring into the breech of the gun, coincident with its axis, reaming out the bore into a slightly conical shape as far as the front of the trunnions, and then inserting into this space a reinforced wrought-iron tube, which is secured in its place by a breech-plug. The exterior of this compound tube is turned to fit the conical space easily, its length being cut so that it will be compressed longitudinally by screwing up the breech-plug, thus communicating to the outer cast-iron portion the - entire longitudinal strain of the powder. Mr. Parsons bases his method on the fact, as stated by him, that wrought-iron may be stretched three times as much as cast-iron, and will offer firom three and a half to six times the resistance within the limit of its elasticity. 6. Krupp gun. Mr. Krupp, of Prussia, makes his guns out of solid cast-steel of low quality. The steel is formed in crucibles in the usual way, and is then run into a large ingot, which constitutes the mass of the gun. This ingot is worked under powerful steam hammers, to give the requisite texture to the metal. In this way 9-inch muzzle-loading rifle cannon, weighing 16,800 pounds, have been made. The success of this manufacture is said to be owing to the very heavy machinery employed, the skillful heating of the large masses to the centre without burning the outside, and the presence of manganese in certain proportions in the iron from which the steel is made. 7. Parrott gun. The Parrott rifle-gun is a cast-iron piece of about the usual dimensions, strengthened by shrinking a coiled band or barrel of wrought-iron over that portion of the reinforce which surrounds the charge. See fig. 160. Fi-. 160. PARROTT GUN. 549 The body of the larger Parrott guns are cast hollow, and cooled from the interior on the Rodman plan. The barrel is formed by bending a rectangular bar of wrought-iron spirally around a mandrel and then welding the mass together by hammering it in a strong castsiron cylinder, or tube. In bending the bar, the outer side being more elongated than the inner one, is diminished in thickness, giving the cross section of the bar a wedge shape, which possesses the advantage of allowing the cinder to escape through the opening, thereby securing a more pertfect weld. The barrel is shrunk on by the aid of heat, and for this purpose the reinforce of the gun is carefully turned to a cylindilical shape, and about one-sixteenth of an inch to the foot larger than the interior diameter of the barrel in a cold state. To prevent the castiron from expanding when the barrel is slipped on to its place, a stream of cold water is allowed to run through the bore. At the same time, and while the band hangs loosely upon it, the body of the gun is rotated around its axis to render the cooling unifoirm over the whole surface of the barrel. Diamensionzs, &c., of PcGrrott Gruns.' B w R E e = >D s eI r - a Gun. C.1, 0 ~. -~ - A n 1 turn tn ft. Inches. Incles. Inches. Lbs. Inches. at Muzzle. Lbs. Lbs. 10-pdr...... 70 3. 11.3 890 3 0.1 10 1 10 20-pdr.... 79 3.67 14.5 1,750 5 0.1 10 2 19 30-pdr... 120 4.20 18.3 4,200 7 0.1 12 3 28 100-pdr.... 130 6.4 25.9 9,700 9 0.1 18 10 86 8-inch... 136 8. 32. 16.300 11 0.1 23 16 150 10-inch.... 144 10. 40. 26,500 15 0.1 30 25 250 The proof of the Parrott guns consists in firing each piece ten rounds with service charges. *A large number of these guns were used in the late war, both on sea and land; and the amount of work done by them, especially in breaching masonry, is probably not exceeded by the rifle-guns of any other system. While a few of them have failed in the service, others have shown very great endurance. The caulse of this The number of Parrott guns procured by the War Department alone was upwards of 1,700, besides 3,000,000 of Parrott projectiles. 550 APPENDIX. failure has been attributed to the bursting of shells in the bore, the presence of sand in the bore, etc., but late investigations show that the Parrott projectiles were frequently broken at the bottom by the force of the powder in such a manner as to wedge the body against the bore. It is quite probable that this cause had much to do with the bursting of the gulls. The inventor thinks he has corrected this evil. V 8. Brooke gain. The gun made after the plan of Captain Brooke, for the Confederate service, resembles Parrott's in shape and construction, except that the reinforcing band is made up of wrought-iron rings not welded together.' In some cases two layers of rings are used. The rifling appeals to be similar to that used in the Blakely guns. 9. Ames gun. The rifle-guns of Mr. Horatio Ames, of Falls Village, Conn., are made of wrought-iron on the built-up principle. Rings of a certain size are made by bending a bar of wrought-iron around a mandrel and welding it together at the ends. Two or more of these rings are carefilly turned in a lathe, and fitted one within the other to form a disk. A number of these disks are welded together, two by two, commencing at the end of a bar of iron, which forms the breech of the gun, and is used for handling it in manufacture. The mass is then reamed out and turned to the proper shape. The trunnions are attached by being screwed into the body of the gun. It is understood that Mr. Ames now proposes to try the experiment of lining his guns with a steel tube. 10. Dahlgreu gun. The Dahlgren guns of large calibre are pmade of cast-iron, solid, and cooled from the exterior. To produce uniformity in the cooling, the piece is cast nearly cylindrical, and then turned down to the required shape, which is shown in the annexed figure. Fig. 160 (a). The thickness of metal around the seat of the charge is a little more than the diameter of the bore, which rule holds good for DAHLGREN GUN. 551 nearly-all qast-iron guns. The chase, however, tapers more rapidly than in other cas-iron guns, which gives the appearance of greater ~thickness of metal at the reinforce. The chamber is of the Gomer formn. The principal guns of this system are of 9 and 11-inch calibre. A piece of 10-inch calibre has, however, been introduced into the Navy, on Admiral Dahlgren's plan, for firing solid shot with 40 lbs. ot powder. The 15-inch and 20-inch Naval guns are shaped exteriorly after the Dahlgren pattern, but are cast hollow and have the elliptical chamber of the Rodman system. JDimensions, &c., of Daldgren guns. Length Maxi-. Maxi- Weight Weight Service of of Gun. of mum Weight. Serv of of Bore. Djain. Charge. Charge. Shot. Shell. Inch. Inch. Lbs. Lbs. Lbs. Lbs. Lbs. 20-inch........... 163 64. 100,000 100 1080 15-inch........... 130 48. 42,000 35 60 400 330 13-inch............... 130 44.7 36,000 40 280 224 11-inch c..........~~.. 132 32. 16,000 15 20 170 130 10-inch........... 1193 29.1 12,000 12J 16 125 100 9-inch.. 107 72.2 9,200 10 13 93 70 125-pdr............... 117k 33.25 16,500 40 125 100 11. Rodmain gun. The principal difficulty formerly experienced in manufacturing very large cast-iron cannon was the injurious strains produced by cooling the casting from the exterior. As far back as the year 1844, General Rodman, of the Ordnance Departmnent, sought to discover the means to overcome this difficulty. After much observation and study, he developed his theory of the strains produced by cooling a casting like that of a cannon, and as a remedy for them he proposed that cannon should be cast on a hollow core, and cooled by a stream of water, or air, passing through it; see page 136. After an elaborate series of experiments the truth of his theory was established, and his new mode of casting was adopted by the War Department. As a result of General Rodman's theory, he claimed that he could cast cannon of any practicable size, and asked that a 15-inch cast-iron gun might be made. This was done in 1860, and the gun was successfully tested shortly afterwards. General Rodman then projected a 20-inch gun, which was made at the Fort Pitt foundry in 1863, under his directions. 552 APPENDIX. Formerly it was customary to use but one kind or size of grain of powder for all cannon, whatever their size. General Rodman proposed for his large cannon that there should be a proportional increase in the size of the grain, expecting thereby to get as high a velocity for the projectile without a corresponding increase in the strain on the breech or weak part of the piece; this led to the introduction of our present Mammoth powder. He also thought that the powder which would produce the least strain on the gun, giving certain initial velocity to the projectile, would be that which should develop its gas as the space behind the projectile increased; or in other words, that the powder should burn on an increasing instead of a decreasing surface. With this object in view he proposed to compress the substance of the powder into short hexagonal prisms, which could be easily fitted together without loss of space. These prisms were perforated with longitudinal holes, from which the combustion of the powder spread. While this idea has to a certain extent been confirmed by experiment, this powder has not been officially adopted in this country; it is understood that it has been to a certain extent in Russia for service in heavy rifle-guns. The trial, or No. 1 15-inch Army gun, has been fired 509 times with charges varying from 35 to 50 lbs. of powder. The effect on the bore is hardly perceptible. The Navy 15-inch trial gun was fired 900 times with charges varying from 35 to 70 lbs., mostly Mortar or Navy cannon powder, when it burst. Within a short time another Army 15-inch gun has been fired without injury 250 times, with charges varying from 40 to 100 lbs. of Mammoth powder; one hundred of these were with 100 lbs. of powder and projectiles of 450 lbs. each. 15-inch gun No. 105 has likewise been fired as follows, viz.: No. times fired. Charge. Weight of projectile. Initial velocity. 4 60 lbs. 430 lbs. 1191 ft. 3'70 lbs. 431 lbs. 1278 ft. 3 80 lbs. 433 lbs. 1355 ft. 3 90 lbs. 453 lbs. 1433 ft. 2 100 lbs. 453 lbs. 1509 ft. The Chief of Ordnance reports that 286 15-inch Rodman guns have been purchased for the use of the Army; besides a large number have been procured for the Navy, for use on the Monitors, RODIMAN GUN. 553 where they rendered good service against the enemy's ironclads and fortifications during the late war. Only, some two or three of the Navy 15-inch guns have split at the muzzle where they had been turned down very thin to fit the port-holes originally intended for the 13-inch Dahlgren gun..A 12-inch rifle-gun, having the exterior form and dimensions of the 15-inch gun, has been made and tested by firing it 420 times without injury, with charges of powder varying from 40 to 85 lbs., and projectiles varying from 475 to 620 lbs.; an initial velocity of 1121 feet was obtained. Further experiments in large rifle-cannon are to be made at Fort Monroe, under the direction of the Chief of Ordnance. 20-inch gun. The 20-inch gun made in 1863 has been thus far fired only eight times, a delay having been occasioned by a failure to get a suitable iron target against which to test its destructive powers. Soon after it was mounted at Fort Hamilton, New York Harbor, it was fired four times with 50, 75, 100, and 125 lbs. of mammoth powder, and solid shot weighing 1080 lbs. In March of this year (1867), it was again fired as follows: 1st fire, 125 lbs. powder, 25Q elevation, 6144 yds. range. 2d " 150' " 25~ " 6860 " " 3d " 175 " " 25~ " 6828 " " 4th " 200 " " 25~ " 8001 " " The maximum pressure on the bore was 25,000 lbs. The form of the 15-inch and 20-inch Rodman gun is shown in fig. 46. Particulars and Charges of -Rodman guns. Name of Gun. [, E x Service Charge. X -i X S Smooth-Bores. In. In. In. Lbs. Lbs. Lbs. Lbs. Lbs. 20-in, gun. 243.5 210. 64. 115200 100 1080 15-in. do. 190. 165. 48. 49100 0ma oth. 17 { 330 mammoth. ~ 17 ~ 425 13-in. do. 177.6 155.94 41.6 32731 30 cannon. 7 280 224 115 for shell. lO-in. do. of 1860 136.66 105.5 32. 15059 18 for shot. 3 127 100 8-in. do. 123.5 110. 25.6 8465 10 1 68 48 554 APPENDIX. 12. Gatling gun. The Gatling gun is a machine gun composed of six barrels made to revolve around a central axis parallel to their bores, by means of a hand-crank. As each barrel comes opposite to a certain point a self-primed metal case cartridge, falling from a hopper, is pushed into the breech by a plunger, and held there until it is exploded by the firing-pin. This gun is capable of firing as many as 200 shots. a minute, with great range and precision. The machinery is simple, and little liable to get out of order. A number of these guns of 1-inch and i-inch calibre have lately been procured by the Government for use on the Plains, in flanking ditches, defending block-houses, etc. In addition to the solid g lb. bullet projected by the gun of 1-inch calibre, this piece fires a cartridge containing 16 smaller projectiles, giving a very destructive fire for short distances. As the weight of this gun-about 1000 lbs.-is very great compared to that of the charge, the aim is not disturbed by recoil. 13. Various guns. The continental nations of Europe have done but little in the manufacture of rifle-cannon throwing projectiles weighing over 100 lbs. In France and Spain the cast-iron sea-coast cannon, corresponding to our 32-pounders, have been banded with steel hoops and rifled. In Russia 9-inch rifle-guns, made of Krupp steel, have been used to a certain extent, but it is understood that one or more of them have failed in service. In the matter of field artillery, most of these nations have rifled their bronze guns, thus making use of the material on hand. The Prussian field guns, however, are made of Krupp steel, and are, breech-loaders. In Russia the Broadwell system of breech-loading has been introduced into the field service. A Tacble of Foreign Cannon, as given by Jiajor Owen, 1R. A. Charge of Nature of Gun. Weight. Powder in terms Projectile. of Projectile. Cwt. Lbs. French 4-pounder (bronze)................ 6~ 1-10 81 French 12-pounder (bronze)............... 12 1-10 25~ French 30-pounder (cast-iron).............. 56 1-9 to 1-13 60 to 100 Prussian 12-pounder (Krupp steel)......... 1-10 13 Prussian - -pounder (cast-iron)............ 53J 1-10 57 Spanish 32-pounder (cast-iron)............ 62 1-9 61 ARMSTRONG PROJECTILES. 555 PROJECTILES. 14. Armstrong projectile. But one kind of projectile is used in the Armstrong breech-loading guns for the field service, and this is so constructed as to act as a shot, shell or case-shot, at pleasure. It consists-fig. 162-of a very thin cast-iron shell (A A), enclosing forty-two segment-shaped pieces of castiron (B B), built up so as to form a cylindrical cavity in the centre (D), which contains the bursting charge and the concussion fuze. The exterior of the shell is thinly coated with lead (C C), *i21 which is applied by placing the shell in a mould and pouring it in a melted state. The lead is also allowed to percolate among the segments, so as to fill up the interstices, the central cavity being kept open by the insertion of a steel core. In this state the projectile is so compact that it may be fired without injury; while its resistance to a bursting charge is so small that less than one ounce of powder is required to burst it. When the projectile is to be fired as a shot, it requires no preparation; but the expediency of using it otherFig. 162. wise than as a shell is doubted. To make it available as a shell, the bursting tube, the concussion and tinwu fuzes, are all to be inserted; the bursting tube entering first and the time-fuze being screwed in at the apex. If the timefuze be correctly adjusted, the shell will burst when it reaches within a few yards of the object; or, failing in this, it will burst by the concussion-fuze when it strikes the object, or grazes the ground near it. If it be required to act as a canister-shot upon an enemy close to the gun, the regulation of the time-fuze must be turned to the zero of the scale, and then the shell will burst on leaving the gun. The explosion of one of these shells in a closed chamber, where the pieces could be collected, resulted in the following number of fragments:-106 pieces of cast-iron, 90 pieces of lead, and 12 pieces of fuze, etc.-making in all 217 pieces. The Armstrong projectiles for the muzzle-loading guns have .55 6 APPENDIX. rows of brass or copper studs projecting from their sides to fit into the grooves of the gun, which are constructed on the shunt principle. Fig. 163 represents a 10-inch Armstrong shell for penetrating armor plates. It is made of wrought-iron, or low steel, with very thick sides. There is no fuze, the explosion resulting firom the heat generated by the impact, and the crushing in of the thin cap which closes the mouth of the powder chamber. The sides and bottom of the shell being thick enough to resist crushing by the impact and also to resist the explosive force of the bursting charge, its effect will, after penetration, be expended on the backing of the armor, or the decks which the armor Fig. 163. is intended to screen. Such projectiles are called " blind shells." 15. Whitwortl projectile. The clross-section of the bore of the Whitworth gun is a hexagon with the corners slightly rounded. The projectile is first formed so that its cross-section is a circle, and its sides taper towards both ends. The middle portion is then carefully planed off to fit the bore of the gun. Fig. 164 represents a Whitworth blind shell for firing against armor plates. It is made of tempered steel, and each end is closed with a screw. To prevent the heat of irmpact from acting too soon on the bursting charge, it is surrounded by one or more thicknesses of flannel. Fig. 164. A 7-inch shell of this kind has been found to have sufficient strength and stiffness to penetrate five inches of wrought-iron before bursting. 16. French projectile. The projectile used in the French field service is made of cast iron, and has twelve zinc studs on its sides, arranged in pairs, so as to fit the six grooves of the gun. See fig. 165. PROJECTILES.:557 For the larger cannon projectiles but three studs are used, and these are cast on the projectile, nearly opposite to its centre of gravity; the bearing sides of the studs are faced with white metal to diminish fiiction against the grooves of the bore. The shape of the grooves is such as to centre the projectile. The latter projectile is used with increasing, the former with grooves of unliform twist. Russian, Austrian and Spanish artillery projectiles belong to the studded, or button class, but differ from each other in the details of their conFig. 165. struction. 17. Blakely projectile. Captain Blakely's projectile has an expanding copper cup attached to its base by means of a single tap-bolt in the centre (see fig. 166). It is prevented from turning by radial grooves cast on the surface of the bottom of the projectile, into which the cup is pressed by the charge. The angle between the curved sides of the cup and the bottom of the projectile is filled with a lubricating material. On the forward part of the body are soft metal studs, more numerous than the grooves of the bore of the piece, that some of them may always form a bearing surface for the projectile against the lands. The driving sides Fig. 166. of the grooves are deeper than the other. 18. Scott projectile. The shell devised by Commander Scott, of the British Navy, for firing molten iron, is shown in fig. 167. It has three ribs cast upon it, which fit grooves so constructed as to centre it in the bore of the gun when fired. The interior of this shell is lined with loam to prevent the heat of the charge from penetrating through to the bursting charge. It is supposed to be broken and its contents diffused on striking the object. 19. Parrott projectile. Capt. Parrott's projectile is composed of a cast-iron body and a brass ring cast into a rabbet formed around Fig. 167. 55 8 APPENDIX. its base (see fig. 168). The flame presses against the bottom of the ring and underneath it so as to expand it into the grooves of the gun. To prevent the ring from turning in the rabbet, the latter is recessed at several points of its circumference. Parrott's incendiary shell has two compartments formed by a partition at right angles to its length. The lower and larger space is filled with a burning composition; the.upper one is filled with a bursting charge of powder, which is filed by a time or concussion-fuse. The burning composition is introduced through a hole in the bottom of the shell, Fig. 168. which is stopped up with a screw plug. 20. Schenkle projectile. Schenkle's projectile is shown in fig. 169. It is composed of a cast-iron body (a), the posterior portion of which is a cone. The expanding portion is a papier mache sabot or ring (b), which is expanded into the rifling of the bore by being forced on to the cone by the action of the charge. On issuing firom the bore the wad is blown to pieces, leaving the projectile unencumbered in its flight. A great difficulty has been fobund in practice in always getting a proper quality of material for the sabot, and in consequence, these projectiles Fig. 169. have not been found to be reliable. 21. Hotchkiss projectile. The Hotchkiss projectile is composed of three parts: the body (a),-fig. 170-the expanding ring of lead (b), and the cast-iron cup (c).. The action of the charge is to crowd the cup against the soft metal ring, thereby expanding it into the rifling of the gun. The time-fuse project tile has deep longitudinal grooves cut on its sides to allow the flame to pass over and ignite the fuse. The last rifle-projectile submitted by Mr. Hotchkiss has an expanding cup of brass attached to its base in a peculiar manner. The cup is divided into four parts by thin projections on the base of the projectile. This arrangement is intended to facilitate the expansion of the cup and to allow the Fig. 1 flamc to pass over to ignite the fuse. PROJECTILES. - 5 59 22. Sawyer projectile. The Sawyer projectile has upon its sides six.rectangular flanges or ribs to fit into corresponding grooves of the bore. To soften the contact with the surface of the bore, the entire surface of the projectile is covered with a coating of lead and brass foil. The soft metal at the corner of the base is made thicker than at the sides to admit of being expanded into the grooves, and thereby closing, the windage. In the latest pattern of Sawyer projectiles the flanges are omitted, and the projectiles are made to take the grooves by the expansion of the soft metal at the base, Wvhich is peculiarly shaped for this purpose. 23. James projectile. The expanding part of James's projectile consists of ahollow (c),-fig. 171-formed in the base of the projectile, and eight radial openings (b), which extend from this hollow to the surface for the passage of the flame of the charge, which presses against and expands into the grooves of the bore, an envelope or patch (e), composed of paper, canvas and lead. (a) represents the body of the projectile, which in this case is a solid shot. (d) is a partition between two of the openings. In a later pattern of this projectile, the internal cavity and radial openings are omitted, and the outside is furrowed with longitudinal grooves Fig. 171. which increase in depth towards the base of the projectile, forming inclined planes, up which the outer covering of lead and canvas is moved by the force of the charge and expanded into the rifling of the piece. 24. Dyer projectile. The Dyer projectile is composed of a cast-iron body (a),-see fig. 172-and a soft metal expanding cup (b), attached to its base. The adhesion of the cup is effected by tinning the bottom of the projectile, and then casting the cup on to it. The cup is composed of an alloy of lead, tin and copper in certain proporL tions. This projectile, as improved by Mr. Taylor at the Washington Arsenal, gives good results for even as large a calibre as 12 inches. (c) represents a corrugated cap of tinned sheet-iron, used with 3-in. projectiles to catch Fig. 172. and direct that portion of the flame of the charge which escapes over the projectile on to the fuze to ignite it. 5(60 APPENDIX. Fig. 173. Fig. 174. 25. Confederate projectiles. The rifle-projectiles used by the Confederates in the late war, belonged, with a few exceptions, to the expanding class. Fig. 173 represents a Confederate wrought-'iron solid shot, for use against iron-clads. For the larger sizes this shot is formed by welding rings around a bar of iron and then turning the mass to the proper size. It has an annular-shaped cup at the base for the purpose of expansion. Fig. 174 represents a shell with a copper ring (b) fitting into a rabbet formed around its base in casting; This projectile would seenl to resemble the Parrott projectile in its construction. The lower edge of the band, however, projects below the bottom of the base, which in Parrott's it does not. Recesses are formed in the sides of the rabbet to prevent the ring from turning. The projectile represented in fig. 175 has a thick circular plate of copper attached to its base by means of a screw-bolt at its centre. To' prevent it from turning around this bolt there are three pins, or dowels, fastened into the base of the projectile, and projecting into corresponding holes in the circular plate. This plate is slightly cupped, and the angle between it and the bottom of the projectile is filled with a greased cord for lubricating the bore of the Fig. 175. gun. EXPERIMENTS ON ARMOR PLATES. 561 Fig. 176. Fig. 177. Fig. 176 represents a projectile of the Blakely class, Kwith its expanding cup of copper (a). Instead of the soft metal studs which are placed on the forward' part of the Blakely projectile, this projectile has a raised band carefully turned to fit the bore. Fig. 177 represents a Reed projectile, in which the expanding cup is made of copper, as shown at (a). This cup is placed in mould, and the body of the projectile is cast upon it. EXPERIMENTS ON ARMOR PLATES. 26. Captain Noble's conclusions. The following conclusions are drawn by Captain Noble, R. A., fiom the results obtained in England firom various experiments carried out under the direction of the Ordnance Select Committee: 1. Where it is required to perforate the plate, the projectile should be of a hard material, such as steel or chilled.iron. 2. The form of head best suited for the perforation of iron plates, whether direct or oblique, is the pointed ogeeval. 3. The best form of steel shell at present known is that in which the powder can act in a forward direction, and which is furnished with a solid steel head in the form of a pointed ogeeval. 4. When chilled iron can be made of the best quality, it is almost, if not quite, as good as ordinary steel for solid shot; and when the projectile can perforate with ease, the chilled shot is more formidable than steel, as it enters the ship broken up, and would act as grape.* * The introduction of chilled iron is due to Major Palliser, who has devoted much time and attention to the subject. 562 APPENDIX. We have every reason to hope that chilled shells can be constructed, which will prove equal, if not superior, to steel.* 5. To attack well-built iron-clads effectively, the guns-should be, if possible, not under twelve tons weight and nine inches calibre, firing an elongated projectile of two hundred and fifty pounds, with forty pounds of powder. 6. When the projectiles are of a hard material, such as steel, the perforation t is directly proportional to the " work"' in the shot, and inversely proportional to the diameter of the projectile; and it is immaterial whether.this "work" is made up of velocity or weight, within the usual limits which occur in practice. 7. The resistance of wrought-iron plates to perforation by steel projectiles varies as the squares of their thickness. 8. Hitting a plate at an angle diminishes the effect as regards the power of perforation in the proportion of the sine of the angle of incidence to unity. 9. The resistance of wrought-iron plates to perforation by steel shot is practically not much, if' at all, increased, by backing simply of wood, within the usual limits of thickness; it is, however, much increased by a rigid backing either of iron combined with wood, or of granite, iron, brick, etc.t 10. Iron-built ships in which the backing is composed of compact oak, or teak, offer much more resistance than similarly clad wooden ships. 11. The best form of backing seems to be that in which wood is combined with horizontal plates of iron, as in the "Chalmer," "' Bellerophon," and " Hercules" targets. 12. An inner iron skin is.of the greatest possible advantage; it not only has the effect of rendering the backing more compact, but it prevents the passage of many splinters, which would otherwise find their way into the ship. No iron-clad, whether iron-built or wooden converted, should be without an inner iron skin. *It is not meant by this that chilled iron would prove superior to the very best tool steel; but that it will be as effective as the ordinary steel hitherto used in the manufacture of projectiles. t Or power of complete penetration.: That is to say, as a shot which is capable of breaking a hole through a 4k-inch plate unbacked, will be also capable of doing so if the plate be only backed by wood, to the extent that, were the plate taken off the backing, the piece of iron where the shot had struck would fall out. EXPERIMENTS ON ARMOR PLATES. 563 13. The bolts known as "Palliser's bolts" are, so far as known at present, the best for securing armor plates. In these bolts the diameter of the shank is reduced to that which it is at the screwed end. 14. Laminated armor is much inferior to solid armor. Captain Noble then proceeds to make the following remarks on the relative merits of rifled and smooth-bored guns against armored vessels, viz.: There are two methods by which an iron-clad vessel can be destroyed by the fire of artillery: 1. Racking (American system), or the impact of heavy shot of large size moving at low velocities, and intended to shatter the vessel's armor, and by repeated shakes ultimately to knock the whole structure to pieces. 2. Punching (English system), or the penetration of the vessel's side, either by elongated shot or shell, intended to kill the crew, blow up the magazine, damage the machinery, and sink the vessel by holes made through her at or near the water-line. Both these systems have their advocates, and there is undoubtedly a great deal to say on both sides. All warlike operations tend to the crippling of your enemy; and that system is evidently the best which will cripple him in the shortest time, in the easiest manner, and at the least possible expense. Now, time is an element which will largely enter into consideration in future actions with iron-clad vessels. Suppose two opposing iron-clads to meet-one armed with guns on the "racking" system, the other with guns on the "punching" system, it is probable that the vessel which could send her shot clean through the side of her adversary would have the greatest chance of reaching a vital part in a given time. Besides which, a "punching" shot is usually an elongated rifle projectile animaeed by a moderately high velocity, and has consequently a flatter trajectory than the " racking" shot, which travels at a low velocity; and as accuracy and a flat trajectory are closely allied, the i" punching" system would gain another chance, viz.: that of' making the greatest number of hits for a given number of shots. Suppose an iron-clad is desirous of running past a fort which defends an important harbor or roadstead. She would, if possible, probably pass at a rate of ten miles an hour. The fort in this case would only have time to fire a few rounds at her, and if the effect of te; 564 APPENDIX. those rounds was merely an external "racking," the vessel might receive no real injury at all-nothing, at least, which would in all likelihood stop her. On. the contrary, a happily directed " punching" shot would have the chance of destroying the machinery, blowing up the magazine, or establishing a leak at the water-line. In attacking an iron-clad by the " racking" system, the whole effect is directed against the casing or armor-plating of the vessel, which, for all offensive purposes, is harmless; the enemy which we want to cripple are the men and guns behind the armor. It appears firom these considerations that an attack on the " punching " system will probably be attended by gain in time, as the vital parts of the vessel cannot be reached so quickly by an attack on the "racking" system. Even were an enemy's ship ultimately shattered and her offensive power destroyed by the effect of heavy blows, this result might not be effected before she had accomplished her object, if not altogether. The attack on the " punching" system is carried on in an easier manner than that on the " racking" system. The former employs light rifle guns, from six to twelve tons; the latter, unwieldy heavy ordnance of from twelve to fifty tons. The "racking" projectiles are heavy cast-iron shot, fired with relatively small-charges, and the loading and working of such projectiles and guns cannot be carried out as easily or expeditiously as in the case of a system which uses a lighter shot and relatively larger charge.* The question of expense is one which, although it should come last in, an inquiry of this nature, is too often made the most important consideration. If, however, we compare the cost of the 9-inch rifled twelve-ton gun as fairly representing the punching system, and the American 15-inch twenty-ton smooth-bore gun as representing the racking system, we shall find that the total cost of gun, carriage and one hundred rounds of ammunition is very much the same for each. On the one hand, the money will have procured a gun which can a The present English system comprises a rifled gun throwing an elongated shot with a moderately high charge, with a view to penetration. If, however, it be desirable to adopt the opposite system, either altogether or in part, there will be no difficulty in employing heavy shot and low charges with our rifleguns. The Americans, however, cannot apply our system to their smooth-bore guns, which is a point in our favor. EXPERIMENTS ON ARMOR PLATES. 565 send a shot, and possibly a shell, through the strongest iron-clad yet afloat at one thousand yards' range. On the other hand, a gun will be obtained which cannot pierce the above ship at any distance whatever; whose shot, at one thousand yards, would, if cast-iron, merely indent the armor and fall back broken into the water, and if' steel, would merely lodge in the ship's side, and whose shell would be absolutely worthless against an iron-clad, and even against wooden ships or earth-works, inferior to the 9-inch rifle shell, both in accuracy and bursting power. Remarks by the Author.-It is probable that Captain Noble bases his estimate of the power of the American 15-inch smoothbored gun on the impression that it can only be filed with low charges of powder. It has been shown, however, that an initial velocity of 1200 feet can be easily obtained with this gun. A projectile, therefore, which weighs 450 lbs., fired friom it, will have a striking velocity at 1000 yds. of 961 ft. equal to a total force of 3230 foot-tons, or 69.3 ftot-tons per inch of the shot's circumference-a force, as shown by Captain Noble, more than sufficient to penetrate the Warrior target. It was with a force probably less than this, that the side of the iron-clad Atlanta was smashed in, and the ram Tennessee was disabled, each by a cored 15-inch shot made of ordinary cast-iron. The power of the 15-inch gun, however, is not limited to 1200 feet initial velocity. Several of these guns of the army pattern have lately been fired with charges as high as 100 lbs. of mammoth'powder, giving an initial velocity of 1500 feet. In one case, as many as 100 rounds have been fired with this charge with no material enlargement of the bore. Within the limit of effective iron-clad warfare, the 15-inch gun has great accuracy of fire. In the trials lately made at Fort Monroe, it was shown that the accuracy of this gun at 1500 yds., with a charge of 100 lbs. of powder, was fully equal to that of the best rifle practice, and that while the least elevation of the rifle-guns was, for this distance, 30 10', that of the 15-inch gun was only 2~ 25'. The latter, therefore, has a flatter trajectory within this distance, and the projectile being round, has greater accuracy in ricochet fire. The advantage, however, which rifle-guns have of projecting loaded shells of peculiar construction (see Armstrong and iVhitworth projectiles), so as to penetrate and explode in the sides of iron-clad vessels, is certainly an important one, and may, perhaps, outweigh, in actual service, the smashing power claimed by the ad TABLE of Results of Experiments with Armor Plates. Taken from Captain Noble's Report. Powder. Projectile.... _ lbs. inches. lbs. inches. feet. "4 Warrior>" 13.3-inch M. L. 70 Rifle Steel shell 612.5 13.24 1046 4646 111.7 Target completely penetrIted,* with much damrifle-gun of L. Go 24.9 age. Range 1000 yards. 23 tons. -: s Horsfall's M. L. 74.4 L. G. Spherical 285 12.88 1290 3288 81.3 Penetrated armor. Shot lodged in backing.. <.B smooth-bore guII cast-iron Range 800 yards. of 24 tons, calibre shot. 13.014 inches. I C)of l2 tons. "Warrior," 1.*9-inch M. L. 23 Palliser's 249 3.89 976 1645 58.9 Penetrated the target completely, buersting on o rifle-gun of chilled shell, passing through. Considerable damage in ~,sy 12 tons. ogival, 1.5 rear; the fragmlents of the shell passed riflegun ofdia L.eters. man ge 1000 y ar. Range 200 yards. 23 tons. 7-inch M. L. gn. 20 7 Steel shell, 116.2 6.92 1397 1572 72.3 Struck one foot to the right of 1296; pene130 cwt. ogival, 1.5 31Penetrated the target completely, bursting in theg. 4Z, (Woolwich.) diameters, backing; base of shell blown back to the screw base. front. Head of shell perfect. Bursting soo-17.0 charge 4.2 lbs. Range 70 yards. Palliser's of24 to s, cchilled shast-iron shells fired uner smilar o.circumstances did not always explode, but iron|~~~~~ 4.X- M.~~~ L. glwere broken up impact. Range 200 yards..5-inch 13 Flat-headed 81.0 4.98 1102 682 40.38 Penetrated armor and burst in backing. Range ~ ~ Whitworth guni. steel shot. 5.42ge 00 yards. 19.0 * The word penetrated in this table means passed through. Wowih.diameers: b ak ing; 1 bas of slRt-ellbonde back to the 12 TAB'LE-(continued). Powder. Projectile. o Target,~~~~~.On,~k * s Tage. Gun. dD aZ o 1 Observed Effects. E=$ a m ~ CH be a) ~~~A c~~~~ It 17 h c i lbs. inches. lbs. inches. feet. 8-in, plates 9-in. M. L. 43 Rifle Palliser's 252.0 8.9 1323 3059 109.4 Penetrated target completely, bursting in t on " Warri- rifle-gun, L. oG.chilled sliell, backing; head uninjured. Struck fair on:t or" backing. 12 tons. ogival, 20. rib, which it broke. Bursting charge 2.37 Direct fire. lbs. Range 200 yards. Same " 43 " Steel shot. 251.0 8.92 1340 3125.1 111.5 Struck inclined target. Scooped out a piece ~ inclined at 17.2 of plate 141 x1l inches; indent 3 inches. H an angle of Slight buckle of plate in rear nothing. 300 with Range 200 yards. horizontal. H Same. " 43 " Palliser's 250 8.9 1313 2989 106.9 Struck upper plate of inclined target 16 in. chilled shell, from 123 and 15 in. from 1241. Diameter of ogival, 20. hole lix 1i in.; depth of indent 19.5 in. to L. head of shell. In rear a rib bent and one ld "Minotaur." wood bolt broken. Bursting charge 2.12 5.5 in. plate, lbs. Range 200 yards. 9 in. of teak, 10.5 in. M. L. 50 " Spherical 150.0 10.37 1620 2730 83.8 Penetrated armor, and lodged in backing. and an inner wrought-iron cast-iron Broke two ribs and seriously bulged the t skin 5/8 in. gun of 12 tons, shot, inner skin. Range 200 yards. The second on ship's shot passed clean through, carrying with it frame. the piece of plate and many splinters, "Bellero- UI plion." 6-in. plate, 10-in. " 35 " Spherical 150.0 10.36 1547 2489 76.5 Cracked and indented plate to a depth of 5 in. of teak and a cast-iron Skin slightly bulged. A steel shot (round) 112 in. in- shot. penetrated armor, and remained in backner skin held ing. Inner skin bulged and cracked. Range by heavy 200 yards. ribs, TABLE-(conitinued). Powder. 5_ __-_ -Powder. in Projectile. e "Lord War- 10.5 in. M. L. 50 Rifle Spherical 168.25 10.43 1576 2898 88.4 Penetrated armor. Hole 11 x 11.5 inch. Shot den." 1-in. wrought-iron L. G. cast-steel broke throulh inner skiv n ad buried itself plalte, 10 inz. gunll of 12 tons. slhot. in ship's timbers. Back shaken. Range 200 teak, 4-in. yards. A shot from a 9.22 in. rifle-gun complate, and 20 dletely penetrated this target and went 500 in. of timber yrds out to sea. "Hercules." 13-in. M. L. 100.0 Ri Cylindherical 573.0 12.94 1268 6388 157 0 Struck 8-i. plate on ribo sle ot stuck in theot 8-in. plate, rifle-gun of steel shot. plte, forcing the pieces into the buried itself 12 ipl. timber 23 tons. 17.0 indent about 13 in. Inner skien. sligtly between bulged; two ribs cracked. Range 700 yds. t tribsak, 4-i. ards. A sot from a 9.22 in. rife-un complate, 18-in. of timber, and inner skin 3/4 inch on iron ribs. Same. 100.0 Cyhilled shot 577.5 12.95 1310 6872 169.0 Struck 8-in. plate juont arib;ove a former shot, ogi-in. pl rifle-ea and patssed throlh te target. This hit 1.25 dihar's. was hardly a fair one, as the rib was weak21.2 enbulged. Shot broke up. Rage 700 yards. Same. 10.5-inch. M. L. 45 " Cylindrical 299.8 10.42 1277 339C 103.6 Penetrated the plate, driving it into the backrifle-guin of steel shot. ilugy, tand slightly bulginig the 3/4 in. inner pl12 tons. e,14.1 iron late. Shot ebounded. Ident 13 i Randnge 200 yards. Same with a 6100.0 Chilled shot 299.8 10.42 142 4221 128.9 Struck fair on 9-in. plate, partly on rib. In9 instead of dent 6.1 irnches. Shot set up 2 inches and an 8-1inch cracked. Diameter of indent 12.75 ind ches. plate. j Range 200 yards. IMPROVEMENTS IN GUN CARRIAGES. 569 vocates of large smooth-bored guns. It shows the importance of not depending entirely on any one system, unless it combines the advantages of both. It is understood to be the present intention of the Government to arm the sea-coast defences with equal proportions of smoothbored and rifle-guns of the heaviest calibres. The only extended experiments with armor plates in this country have been made by the Naval Ordnance Bureau, the most important details of which have not been published. A general summary of these results, as given in a report of the Chief of this Bureau, will be found on page 473. 27. Improvements in Gun Carriages.-The Ordnance Department has lately made and tested certain wrought-iron field and siege carriages. The principal improvements aimed at in one of the patterns of field-carriages on the wooden carriages now in use, are: 1. Lightness and cheapness. 2. Placing the pintle about two feet in rear of the limber axletree, so that the trail of the gun-carriage shall counterpoise the weight of the pole, and thereby relieve the shoulders of the wheel-horses which have now to support it. 3. Bringing the trunnion beds nearer to the axletree, thereby diminishing the liability of overturning the carriage in travelling. 4. Allowing no part of the carriage to project below the plane of the axletrees. This is found necessary to prevent the breaking of the implement fastenings in passing over stumps, stones, &c. 5. More convenient modes of carrying the rammers and trail handspike. 6. As the 12-pdr. carriage can be made of wrought-iron, so as to be little if any heavier than the wooden carriage used for mounting the 3-inch rifle-gun, but one carriage will be required for the field-service. In this case thimbles or washers will be required to fit the trunnions of the 3-inch gun into the trunnion beds of the 12-pdr. carriage. The very large stock of wooden carriages now on hand may delay, on the score of economy, the introduction of wrought-iron carriages for some time 40to come; but that such carriages can be made superior to wooden ones scarcely admits of doubt. INDE X. Absolute force of gunpowder, 55. Arquebuse, history and description of Accidents, from the spontaneous com- the, 273. bustion of charcoal, 17; with per- Arsenals, how classified, 268. cussion locks, 297. Artillery, material of, 108; system of, Aiming a fire-arm, 299. 108; first system of, in the 16th cenAir, effect of the resistance of, on a rifle tury, 109; second system of, in the projectile, 177; resistance of the, reign of Louis XIV., 110; Valiere's 402; fall of a projectile in the, 404; system of, 110; Gribeauval's system trajectory in the, 412-424. of, 111; Louis Napoleon's system of Alcohol in pyrotechny, 347. 112; stock trail system of, 112; imAmes gun, 550. portant recent improvements in, Ammunition for small-arms, 348; for 113; General Paixhan's system of, field and mountain cannon, 351; for 166; implements and machines for, siege and sea-coast cannon, 353; 248. preparations for the service of, Artillery carriages, classification of, 358. 212; preservation and repairs of, Analysis of gunpowder, 30. 259; how to destroy, 259; materials Ancient arms, 270. for, 261-266; construction of, 267; Ancient guns, 106. painting of, 268. Ancient howitzers, 107. Artillery harness, 215, 218. Ancient mortars, 106. Artillery wheel, 220. Ancient theory respecting length of Astragal of field-guns, 115. cannon, 1427. Attachment of artillery harness, 216, Angle of arrival, in ricochet fire, 453. 217. Angle of fire, definition of, 437; in ri- Austrian army bullet, 313. cochet firing, 455. Axle-tree of the artillery carriage, 226; Angle of sight, definition of, 437. of the field-limber, 231. Antimony in pyrotechny, 345. Appendix, 541. Back-action lock, 297. Armament of sea-coast batteries, 503. Bags of powder, explosive force of, 376. Armor, ancient, 272. Ballistic machine at West Point, 390, Armor, defensive, 286. 395; table of times calculated for, Armor plates, 471, 561. 525. Armorer, dismounting of fire-arms by Ballistic machine of Captain Navez, an, 335. 389. Armories of the United States, where Ballistic pendulum, 383, 388. situated, 320. Ballistics, history of, 382. Arms, package and storage of, 330; Balloting in the bore a cause of rotapreservation and care of, when in tion, 425. service, 332. Bands of portable fire-arms, 300. Arms in service, inspection of, 336. Barbette sea-coast carriages, 247. Armstrong's rifle-gun, 541; projectiles, Barrel of portable fire-arms, 290; 555. length of, 316-319; inspection of;, 328. 572 INDEX. Barrel of the rifle-musket, how cleaned, 206; liable to injury from lodge. 333. ment, 210. Bar-shot, description of, 83. Brooke gun, 550. Base of the breech of cannon, 115. Browning musket-barrels, 327. Base-ring of cannon, 115. Buckshot cartridge, 349. Battery-wagon, how employed, 236; Budge-barrel, for carrying cartridges, description of, 237. 252. Battle-axe, ancient, 270. Buildings for pyrotechny, how arBayonet, origin and history of the, ranged, 342. 276; description of, 280; inspection Bullets for small-arms, 76; present of, 329; when unserviceable, 337. form of expanding, 312; in use in Beeswax and tallow, a lubricant for the United States and Europe, 312, fire-arms, 316; in pyrotechny, 347. 314; elongated, proper charge of Bill-hook, 259. powder for, 315; how made, 348; Bill of timber, 266. effects of, 486. Blakeley gun, 545; projectile, 557. Butt of a musket, length and shape of, Blistered steel, how made, 140. 298. Blue color, how produced on the sur- Butt-plate of portable fire-arms, 300. face of iron and steel, 326. Blue-light, ingredients for, 369. Cadet-musket, description of, 317. Bombard, early cannon, 104; how con- Caisson, description of the, 235; how structed, 105. to destroy, 259. Bomford, Colonel, plan of, for deter- Cake powder made by compression of mining pressure of the charge in grain powder, 52; compared with cannon, 152; columbiad invented grain powder, 154. by, 190. Calibre of cannon, 107; of siege-guns, Borda,.experiments of, in relation to 184; of portable fire-arms, 293. the forms of projectiles, 410. Calibres in the American service (note), Bore, influence of length of, on velocity 107. of.projectile, 127; effect of length of Canister fire, 468; of field artillery, on maximum charge, 131; length of, 492. in field cannon, 180; use of projec- Canister-shot, description of, 81. tiles not suited to, 435. Cannon, shape of the first, 104: early, Bore of cannon, 116; inspection of, construction of, 105; calibre of, 107; 201; enlargement of, 208, 210. devices on, 108; construction of, Bore of fire-arms, length of, 127. 114; interior form of, 116; influence Bore of rockets, 96. of length of bore of, on velocity of Boring cannon, 199; vent of cannon, projectile, 127; materialsbest adapt200; musket-barrels, 323. ed for the construction of, 131, 132; Bormann fuze, description, 362. strength of, how affected by cooling, Bow, the ancient, 271. 134; course of the fracture of, in Breach, firing-in, 496. bursting, 136; materials principally Breaching walls of'fortifications, 481; used in the fabrication of, 138; with rifle-cAnnon, 485. thickness of the metal of. 151.; exBreech of cannon, 115; best form of, terior form of, 151; nature of force for strength, 120; thickness of, 157. to be restrained by, 153; various Breeching of artillery horses, 219. kinds of strain upon, 154; nomenBreech-loading arms, 301; advantages clature of the exterior of, 157; pecuof, 307. liar form of, made in Sweden, 159; Breech-loading cannon, early, 105; position of the centre of gravity of, projectiles for, 170. 163; weight of, how determined, Breech-sight,.lhow used, 255. 165; different kinds of, 166; rifled, Breech-screw of portable fire-arms, 167; uses to which applied, 180; 291. mountain and prairie, 183; for seaBritish service bullet, 313. coast batteries, 188; where made, Bronze as a material for cannon, 138; 194; proof of, 205; bronze, how density and tenacity of, 139. proved, 206; inspection marks on, Bronze cannon, copper vent-pieces 207; how marked when rejected, made for, 117; injured by the melt- 207; injuries to, caused by service, ing of the tin, 139; inspection of, 207; how disabled, 260; cost of, 204; defects in, 205; how proved, 547. INDEX. 5 73 Cannon-balls, preservation and piling tion on the combustibility of, 19; of, 93. quantity of, in gunpowder, 31; pulCarbine, description of, 317. verized, used in the process of castCarcass, description of,- 84; composi- ing cannon, 196; in pyrotechny, tion and preparation of, 371. 345. Carriage of Armstrong gun, 540. Charge, force of, influenced bythe form Carriages, artillery, 212; materials of its seat, 120; influence of windage for, 261-266. on the force of, 125; maximum, Cartridge-bags, how made, 352, 353. 130; the most suitable for smoothCartridge of the rifle-musket, 349. bored cannon, 131; proportion of, to Cartridge with buckshot, 359. weight of projectile, 131; effect of Cartridge, metallic, 302. length of bore on maximum, 131; to Cartridges, materials for preparing, determine the pressure of, by calcu348; for small-arms, how packed, lation, 151; to determine the pres349; number expended in European sure of, by experiment, 152; for fieldwars, 469. guns and howitzers, 181; for siegeCascable of cannon, parts of the, 114; guns, 185; for proving cannon, 206; knob of the, 163. in ricochet fire, to find, 455. Case-hardening, the process of, 325. Charge of rupture of shells, 84. Casemate carriages, 247. Chase of cannon, 115; thickness of, Casemate howitzer, 193. 158. Casemate truck, for moving cannon, Chassis for sea-coast gun-carriages, 250. 245. Case of a signal rocket, 366. Chassis-rails, props of, 247, Cases for fireworks, how made, 357. Cheeks of artillery carriages, 226. Case-shot, description of;, 80; fabrica- Chlorate of potassa, used in the manution of spherical, 88; when to be facture of gunpowder, 14; in pyrofired in defence or attack of a work, techny, 344. 496. Classification of cannon, 114; of artilCast-iron, projectiles of, 72; effect of lery carriages, 212; of arms in sercooling on the strength of cannon vice, 339; of fires, 450. made of, 134; better adapted for Closing the breech of breech-loading large than small cannon, 136; ad- arms, 302. vantages and disadvantages of, as a Coehorn mortar, description of, 188. material for cannon, 145; causes Coke-wash, use of, in the process of which affect the quality of, 145; how casting cannon, 198. tested for cannon metal, J45; gen- Coloring materials in pyrotechny, 346.:eral properties of, 147; tenacity of, Colt's pistol, description of, 318. injured by the presence of sulphur, Columbiads, history and description 4149; endurance of, 211; injuries to of, 190; improved model of, adopted cannon made of, 211; effect of pro- in 1860, 191; dimensions of the imnjectiles on, 471. proved, 192; large, and -iron-plated Cast-steel, how made, and characteris- vessels (note), 47'3: ranges of, 532; tics of, 141. the 16-inch, description of, 551. Cavalry, effect of field artillery against, Columbiad-shell, bursting charge of, 490. 355. Cavalry sabre, description of, 284. Combined metals, as materials for can* Cavities in cannon, how produced, 208. non, 149. Centre of gravity of projectiles, 74; Combustibility of various kinds of effect of the position of, 178. charcoal, 18, 19. Centre of gravity of cannon, position Combustion of gunpowder, velocity of, of, 163. 39; nature of the products of, 52; Chain-ball, proposed to be attached to gaseous products resulting from, projectiles, 75. 53. Chain-shot, 83. Compositions for military fireworks, Chambers of fire-arms, 121-123. 356; for signal rockets, 366. Charcoal, 15; properties of, 16; quality Compound projectiles, 73. of, affected by temperature in manu- Compressible fluid, resistance of, 403. -facture, 16; spontaneous combustion Compression, strain by, upon cannon, of, 17; combustibility of various 154. kinds of, 18, 19; influence of tritura- Concave cutting-edge, action of, 283. 574 INDEX. Concentric projectiles, effect of rotation! Defensive weapons, ancient, 272. on, 427. Definition of velocities of projectiles, Concussion fuze, description of, 364. 384. Cone of' portable fire-arms, 292; defects Deflection of the Armstrong gun, 540. in, 337. Delvigne's improvements in loading Confederate projectiles, 560, 561. rifles, 309. Congreve rocket, how guided, 99. Density of a charge of gunpowder of Congreve, Sir William, improvements cylindrical form, 62. made by, in the construction of Density of gases developed in the comrockets, 102. bustion of gunpowder, 58. Conical chambers of fire-arms, 122. Density of gunpowder, influence of, on Construction of artillery carriages, the velocity of combustion, 43; in 267. relation to force, 56. Construction of early cannon, 105. Dgrivation, or drift, causes of, 432. Construction of cannon, 114. Destruction of artillery, 259. Construction of rockets, 94. Determination of equations of motion, Continuous effort exerted by draught- 395-400. horses, 214. Deviation, 294, 424; conclusion respectConvex cutting-edge, action of, 283. ing the causes of, 429; of oblong Cooling, effect of, on the strength of projectiles, 431; effect of wind in cannon, 134; unequal, effects of in producing, 433; summary of the cannon modified by time, 137; influ- causes of, 433; measure of, 460.; verence of, on the color and texture of tical and horizontal, 461; with the cast-iron, 149. 15-inch columbiad, 565. Cooling cannon, 136, 198. Devices on old cannon, 108. Corrosion, cannon metal should be able Didion, Captain, on trajectory in the. to resist, 138. air, 412. Counter and enfilading fires with siege Different kinds of cannon, 166; smallcannon, 494. arms, 316; fires, 450. Cracks in cannon, how produced, 208; Dimensions of siege mortars, 186; of on the exterior, 211. the siege howitzer, 186. Crossbow, the ancient, 272. Direct fire, when used, 450. Cuirass and helmet, description of, Direct fire of field artillery, 490. 286. Disabling cannon, 260. Curving plates for musket-barrels, 321. Discharging fire-arms, 435. Cuts in cannon, 210. Dish of the artillery-carriage wheel, Cutting-arms, 282. 221. Cutting and filing in the manufacture Dismounting arms by a soldier, 332; of small-arms, 325. by an armorer, 335. Culverins, 106; very long one cast Dispart of cannon, 116. during the reign of Charles V., 127. Distance of objects, how estimated, Cylinder and cap in ammunition, 352. 446. Cylinder-gauge, 201. Distillation, charcoal made by, 16. Cylinder-staff, 200. Drag-rope, 258.. Cylindrical chambers, for fire-arms, Draught-harness of the artillery horse, 122; injurious effect of, on heavy 218. cannon, 123. Draught-horses, force exerted by, 213; table relating to the force of, 214; Dahlgren, Captain, two -vents placed ordinary load per day for, 215. by in his naval guns, 209; experi- Drift, or derivation, causes of, 432. ments of, in relation to deviation, Drifts, for use in making fireworks, 430; guns, 550. 358. Damascus steel, how made, 287. Drilling and tapping of lmusketsbarDamask steel, appearance of, how pro- rels, 323. duced, 142. Driving.-the composition of rockets, Dardanelles, defence of, by means of 367. stone projectiles, 72. Dry compositions for fireworks, 356. Decorations of signal rockets, 367. Drying gunpowder, 25. Defects in parts, of fire-arms, 337-339. Ductility, a desirable quality in cannon Defects of timber trees, 265. metal, 133. Defensive armor, 286. Ductility of wrought-iron, 144. INDEX. 575 Dupont's gunpowder compared with Face of cannon, 115. Hazard's, 544. Fascines, pitched, for incendiary purDurability of the musket-barrel, 339. poses, 374. Dyer projectiles, 559. Fall of a projectile in the air, 404, 422. Felling timber for artillery purposes, Early cannon, shape of, 104; construc- 264. tion of, 105. Field ammunition, 351. Earth, effect of projectiles on, 485; Field artillery, range of;, 462; employ.penetrations of projectiles into, 489. ment of, 488. Eccentric handspike for sea-coast car- Field cannon, how classified, 180; riages, 257. weight of, 180; length of bore of, Eccentric projectiles, effect of rotation 180; charges of, 181; material for, on, 427. 181; the Napoleon, 182; rapidity of Eccentric turning, 324. fire of, 449. Eccentricity in projectiles a cause of Field carriages, turning of, 232; charrotation, 425. acteristics of, 234; varieties of, 234. Eccentrometer, uses of the, 426. Field-guns, ranges of, 527. Effective range of field artillery, 488. Field howitzers, range of shells fired Effect of fire in general, 459. from, 492; ranges of, 527, 528. Effects of gunpowder, 35; projectiles, Field-limber, construction of the, 230. 471. Field rifle-gun, Rodman's, 182. Elasticity of material for cannon, 132. Field-shells, uses and range of, 463; unElasticity, absence of, in cast-iron can- der what circumstances to be used, non, 145. 493. Electro-ballistic machines, 389. Fillets of field-guns, 115. Electro-ballistic machine at West Filling-shells, 355. Point, 390-395. Fire-arms, important recent improveElevating arc of the sea-coast carriage, ments in, 113; shape of the cham245. bers of, 121; length of bore of, 127; Elevating screw of the sea-coast car- maximum charge of, 130; recoil of, riage, 244. 130; strongest near the bottom of Elongated bullets, proper charge of the bore. 157; various modes of powder for, 315. rifling, 168; portable, 273, 290; Elongated projectile, advantages of loading, pointing, and discharging,. pointed out by Robins, 309. 435. Employmentoffield artillery,488; siege Fire-ball, for lighting up enemy's cannon, 493; sea-coast cannon, 512. works, 373; use of, in attack or deEndurance of cast-iron cannon, 211; of fence, 498. the 15-inch columbiad, 552. Fire, preparations for communicating, Enfilading and counter fires with siege 380. cannon, 494. Fire, tables of, 447; rapidity of, 448. Enlargement of bore, how produced, Fire in general, effect of, 459. 208. Fire of case-shot, in attack or defence, Equations of motion, 406-409; deter- 496; of the siege howitzer, 497; of mination of, 395-400. mortars, 499. Equipments and implements for artil- Fire-stone, description, preparation, lery, 251. and use of, 370-371. Escape of gas from breech-loading Fireworks, proportions of nitre, chararms, 302. coal, and sulphur for, 42; military, Etching on a sword-blade, 289. 356; for signals, 366; incendiary, Expanding bullets, present form of, 370; for light, 372-375; ornamental, 312. 376; offensive and defensive, 376. Expanding projectiles, 169. Firing at night, 444. Explosion of gunpowder, phenomenon:Firing in breach, 496. of, 38. Firing to effect a breach, rules for, 484. Explosive force of gun-cotton, 70. First reinforce, thickness of, 157. Exterior of cannon, 151; nomenclature Fixed ammunition, 353, of, 157. Flame in ornamental fireworks, 378. Flats of portable fire-arms, 292. Fabrication- of projectiles, 88; of Flight of projectiles, to determine time sword-blades, 287. of, 422. 5706 INDEX. Flint-lock, when introduced and dis- Gomer chamber of fire-arms, advancarded, 276. tages of, 123. Foot artillery sword, 285. Graduation of rear-sights, 445. Foot-boards of the field-limber, 232. Grain of various kinds of gunpowder, Force, loss of, fromwindage,124; nature 27; results of experiments on six of, to be restrained by cannon, 153. sizes of, 67. Force of draught-horses, table relating Grained powder and caked powder, 154. to, 214. Granulating gunpowder, 24. Force of gunpowder, 55; relation be- Grape and canister, inspection of, 91. tween, and density, 56; when in- Grape and canister firing, 468. flammation is instantaneous, 58; Grape-shot, how composed, 80. when inflammation is not instanta- Gray iron, characteristics of, 147. neous, 60; when inflammation is in- Greener's rifle projectile, 311. stantaneous or progressive, 66. Grenades, 79. Forces acting on a gun-carriage, 228. Gribeauval's system of artillery, 111; " Forcing " projectiles into rifle-barrels, his method of attaching artillery 307. horses, 217. Forge, -travelling, description of, 236. Grinding a sword-blade, 288; smallForging a sword-blade, 287. arms, 325. Fork of the field-limber, 231. Grommets or ring-wads, 355. Form of a table of fire, 448. Grooved balls, 75. Form of cannon, 151. Grooves, form of, in rifled fire-arms, 171, Form of projectile, theory in relation comparative advantages of variable to, 409; results of experiments in re- and uniform, in rifled fire-arms, 173; lation to, 411. method of cutting, in cannon, 173; Form of siege-guns, 185. number, width, and shape of, in canFormula for initial velocity, 385. non, 174; inclination of, in rifled fireFraser gun, 542. arms, 175-179; objects to be attained. French army bullets, 313. by, in rifles, 294; kind adopted by the French musket-barrel, durability of, United States Government, 295; ro339; guns, 554; projectiles, 556. tation produced by, in gun-barrels, Friction, the object of a carriage-wheel 294. to diminish, 221. Guard-bow of portable fire-arms, 300. ~Friction-powder, composition of, 360. Guard-plate of portable fire-arms, 300. Friction-tube for firing cannon, 359. Gum-arabic in pyrotechny, 347. Front sight of portable fire-arms, 299. Gun-carriages, classification of, 225; Funnel, for loading shells, 254. important requisites of, 225; forces Furnaces in laboratories, 343. acting on, 228; construction of, 234; Furrows in cannon, how produced, 208. sea-coast, 243; improvements, 569. Fuze instruments, 253. Gun-cotton, how prepared, 68; projecFuzes, percussion, concussion, and time, tile force of, 69; explosive force of, 70. 360-366. Gun-metal, character of, 146; density and tenacity of, 147. Galileo on the path of projectiles, 382. Gun-pendulum, for determining velociGarrison and siege cannon, 184. ties, 388. Gas, law of formation of, in the combus- Gun-platform, how constructed, 242. tion of gunpowder, 44-46; table of Gunner, implements carried by, 254. quantities of, developed from various Gunnery, science of, 382. grains of gunpowder, 48; loss of, by Gunpowder, general theory of, 7; comthe fuze-hole of a shell, 87; escape position of, 8; manufacture of, 21-23; of, from breech-loading arms, 302. pressing and granulating, 24; simple Gases developed in the combustion of method of manufacturing, 25; glazgunpowder, density of, 58. ing, drying, and dusting, 25; general Gatling gun, 554. qualities of good, 27; inspection and Gauges for inspecting fire-arms, 336. proof of, 27; size of grain of various Gerbe, in ornamental fireworks, 377. kinds of, 27; specific gravity of, 28; Gin, an instrument for raising cannon, mercury densimeter for, 28; initial 248. velocity of, 29; how packed, 30; inGlazing gunpowder, 25. spection report as to the qualities Globe and telescopic sights of fire-arms, of, 30; quantity of charcoal in, 31; 299. quantity of saltpetre in, 31; hygro INDEX..577 metric qualities of, 32; quantity of Haversack, gunner's, for carrying carsulphur in, 32; quickness of burn- tridges, 252. ing of, 33; unserviceable, how re- Head-gear of artillery horses, 218. stored, 33; storage and preservation Heavy charges for cannon, 120. of, 34; history of, 35; transportation Helmet and cuirass, description of, of, 35; effects of, 35; phenomenon 286. of explosion of, 38; ignition of, 38; History of gunpowder, 35; of rockets, combustion of, progressive, 40; in- 102:; of cannon, 104; of small-arms, fluence of purity and proportions of 270; of ballistics, 382. ingredients on combustion, 41; in- Hollow projectiles, cavities of, how fluence of density of, on velocity of made, 89; inspection of, 91, 92. combustion, 43; effects oftrituration Hollow-shot, various denominations, of ingredients, 43; velocity of com- 77. bustion 6f, increased by moistening Hotchkiss' rifle-projectile, 558. and subsequent drying, 44; law of Hot-shot, hay wads used for, 355; how formation of gaseous products from, prepared and used, 372. 44; combustion of a spherical grain Hounds of the field-limber, 231. of, 45; combustion of a polyhedral Howitzers, ancient. 107; characterisgrain of, 46; combustion of a grain tics and use's of the, 166; for mounof ordinary, 47; inflammation of, tain service, 183; for siege purposes, 49; influence of the size of the grain 186; weight of, 180; for sea-coast of, on combustion, 49; velocity of service, 193; how proved, 206; how inflammation of, diminished by com- pointed, 439; trajectory of projecpression (note), 52; products of the tiles of, 414-418; mountain, range combustion of, 52; gaseous products of, 463. resulting from the combustion of, Howitzer carriages, construction of, 53; for war purposes, proportions of, 234. 53; temperature of the gaseous Hutton on the paths of projectiles. products of, 54; determination of the 383; experiments of, in relation to force of, 55; relation between the the forms of projectiles, 410. density and force of, 56; density of Hygrometric qualities of gunpowder, the gases developed in the combus- 32. tion of, 58; force of. when inflammation is instantaneous, 58; force of, Ignition of gunpowder, 38. when inflammation is not instanta- Implements and equipments for artilneous, 60; density of a cylindrical lery, 2.51. charge of, 62; expansive force of in- Incendiary fireworks, 370. stantaneous or progressive inflam- Incendiary match, how made, 372. mation of, 66; results on velocity, Inclination of grooves in rifled fireof various densities of, 67; for prov- arms, 175; limit of, 17 9. ing cannon, 205; injuries to cannon Inclination most suitable for grooves from, 208; in pyrotechny, 345. in rifled fire-arms, 179. Guns, ancient, 106; distinguishing Incompressible fluid, resistance of, characteristics of, 166; how proved, 402. 206; how pointed, 439; for sea-coast Incorporating ingredients of gunpowservice, 190; trajectory of projectiles der, 23. of, 414-418. Infantry, effect of field artillery against, 489. Halberd, 271. Inflammation of gunpowder, 49; cirHale's rocket, 98. cumstances influencing the velocity Hand-arms, ancient, 270; classification of, 50; force developed by instantaof, 277; general principles of, 277. neous, 58; force developed by, when Hand-grenade, 79; description of not instantaneous, 60. Ketchum's (note), 80. Ingredients of gunpowder, 21. Handles of bronze field-piecss, 163. Initial velocity, of gunpowder, 29; of Handling the sabre, 283. projectile fromn rifled fire-arms, 174; Hardening and tempering steel, 326. with American small-arms, 316-319; Hardness a necessary quality in can- of projectiles, 384; causes affecting, non metal, 137. 387; formula for, 385; practical Hardness of wrought-iron, 144. rule for, 387; determination of, by Harness for artillery horses, 215. experiment, 388; of a mortar-shell Vt- O57 8 INDEX. to find, 421; causes which affect, of, on velocity of projectile, 127; ef. 424. fect of, on maximum charge, 181; Initial velocities, table of, with service experiments to determine the influ. charges, 387; tables of values for, ence of, 128; of field cannon, 180; 508, 514. of siege-guns, 185. Injuries to cannon, caused by service, Length of projectiles, effect of, 175. 207; from the projectile, 209. Length of stock of field carriages, 233. Inspection of gunpowder, 27; of pro- Level, gunner's, description of, 254. jectiles, 90; of cannon, 200, 201; of Lever-jack, 250. bronze cannon. 204; of sword-blades, Lifting-jack, 250. 289; of small-arms, 327; of arms in Light-artillery sabre, description of, service, 336. 284. Inspection marks on cannon, 207. Light-balls, 374. Inspection report as to the qualities of Light-barrel, how constructed, 376. gunpowder, 30. Light charges for cannon, 121. Instruments for the inspection of hol- Limber, object of the, 230; for siege low projectiles, 91; for the inspec- carriages, 240. tion of cannon, 200. Limbering, difficulty of the old system Interchange of parts in similar arms, of, 232. 320, 339. Line of fire, definition of, 437. Interior form of cannon, 116. Line of sight, definition of, 436. Iron cannon, how proved, 206. Liquid compositions for fireworks, 356. Iron ores used by the United States Load of pack-horses, 213; of artillery Government for the manufacture of horses, 215; of field carriages, 233. cannon, 146. Loading cannon, implements for, 251. Iron parts of a gun-carriage, 227. Loading fire-arms, 435; improvements Iron-plated ships, the smaller sea-coast in, 276. guns useless against, 189; effects of Loading rifles, various modesof, 307. projectiles on, 472. Lock of a portable fire-arm, 295; conIron sling-cart, for moving cannon, 249. ditions to be fulfilled in the conIrreparable arms, 339. struction of, 296; inspection of, 330; defects in, 338. James' rifle, dimensions of, 319; pro- Lock of a rifle-musket, how cleaned, jectile for, 559. 334; how taken apart, 335. Javelin, Roman, 271. Locking wheels of artillery carriages, Jets, in movable fireworks, 379. 233. Lodgement, injury to cannon caused Knob of the cascable, 163. by, 209; means used to prevent, 210. Krupp gun, 548. Longitudinal strain upon cannon, 154. Long ranges of siege cannon, 493..Laboratory, military, how it should be Loss of velocity by resistance of the situated, 342; precautions to be used air, 406. in, 343. Louis Napoleon's system of artillery, Lackering projectiles, 93. 112. Ladle, for withdrawing projectiles, Lubricant for fire-arms, 315. 252. Lampblack in pyrotechny, 346. Macedonian lance, 270. Lance, description of the, 279; advan- Machines and implements for artillery, tages of the use of the, 280; mode 248. of carrying on horseback, 280. Magnus, Prof., apparatus devised by, Lance, Macedonian, 270. 428. Lance, in ornamental fireworks, 377. Manoeuvre of artillery carriages, imLand-batteries, advantages of; 502. plements for, 256. Large cannon for sea-coast batteries, Manceuvring handspike for sea-coast 189. carriages, 257. Law of resistance, 402. Manufacture of cannon, 194; of smallLead, projectiles of, 72. arms, 320; of sword-blades, 287. Length of barrel, of portable fire-arms, Marks, inspection, on cannon, 207. 294; influence of, on velocity of pro- Marrons in signal rockets, 369. jectile, 294. Martello tower, rapid destruction of Length of bore, of fire-arms, influence one with rifle projectiles, 485. INDEX. 579 Masonry, effect of projectiles on, 480. Motion of rockets, 95, 96; of a projecMatchlock, description of the, 274. tile in vacuo, 395. Materials for the fabrication of cannon, Mottled iron, characteristics of, 148. 138; for field cannon, 181; for sea- Mould for casting cannon, how formed, coast carriages, 243; for artillery 196. carriages, 261-266; for pyrotechny, Moulding cannon, process of, 195. 344-348. Mountain ammunition, 351. JMateriel of artillery, 108. Mountain cannon, 183. Maximum charge of fire-arms, 130. Mountain howitzer, 183. Maynard's primer, how made, 350. Mountain howitzer carriage, requisites Maynard's self-priming percussion of, 237; description of, 238. lock, 297. Mountain shells, ranige of, 463. "Mealed powder," 37; in pyrotechny, Mountings of portable fire-arms, 300; 345. inspection of, 330. Measure of deviation, 460. Mountings of rifle-musket, how cleaned, Measures, for charges of powder, 254. 334. Mechanical principles determining ini- Movable pieces of fireworks, 378. tial velocities, 384. Mules as pack-animals, 213. Men's harness, 258. Multipliers, tables of, 505. Mercury densimeter for gunpowder, 28. Musket, introduced by Charles V., 274; Metal for cannon, qualities desirable boxes for packing, 330. in, 132; the various kinds used, Musket-barrels, how made, 321; how 138. browned, 327; defects in, 337; du Military fireworks, 356. rability of, 339; strength of, 340. Mill-cake, pressing, 24. Mutzig, trials made at, as to the Milling, in the manufacture of small- strength of musket-barrels, 340. arms, 324. Muzzle of cannon, 116; enlargement Minie, form of projectile proposed by, of, 210. 309; his rifle projectile, 311. Model, wooden, for moulding cannon, Nail-ball, 75. 195. Napoleon field-gun, description of, 182, Models for ordnance materiel, 268. advantages and disadvantages of, Molten iron used for incendiary pur- 183. poses (note), 372. Natural angle of sight, 116, 181; of Momentary effort exerted by draught- siege-mortars, 187. horses, 214. Natural line of sight on cannon, how Mordecai, Major, results of experi- marked, 207. ments of, with gun cotton, 69; ex- Natural point-blank, definition of, 438. periments of, on the influence of Natural steel, 140. length of bore, 129. Nave-box of the artillery carriage, 227. Mortar,Lnitre obtained from, 12. Navez, Captain, ballistic machine of, Mortar, a term applied to early cannon, 389. 104; ancient, 106; characteristics Neck of cannon, 115. and uses of, 167; for siege purposes, Newton on the path of projectiles, 186; form of, adopted in 1861; 187; 382. spherical case-shot, for, 188; how Night-firing, 444. proved, 206; inspection of. 204; how Nitrate of soda, 15. pointed, 442; fire of, in attack or de- Nitre, preservation of, 12; refining of, fence, 499; case-shot, fire of, in at- 12; for laboratory use, 344. tack or defence, 501; uncertainty of Nitre-beds, how made, 11. the fire of, from shipboard, 504. Nomenclature of artillery carriages, Mortar-fuze, description of the, 361. 225; of cannon of old pattern, 114; Mortar-platform, how constructed, 242. of artillery carriage-wheels, 220; of Mortar-scraper, 254. portable fire-arms, 291; of a percusMortar-shells, 79; bursting charge of, sion lock, 296. 355; table of times of flight of, 401; table of ranges of, 401; to find the Oak, effect of projectiles on, 474, 481. initialvelocity of, 421; how fired, 436; Objects, distance of, how estimated, fire of, 464; tables of fire, 522, 528. 446. Mortar-wagon for siege purposes, 240. Oblong bullet, description of, used in Motion, equations of, 406, 409. the United States service, 77. 580 INDEX. Oblong projectiles, superiority of, 74; Polishing a sword-blade, 289; smalltrajectory of, 423; deviation of;, 431. arms, 325. Offensive and defensive fireworks, 376. Poplar, charcoal for gunpowder made Ordnance and ordnance stores, what from, 15. constitute, 108. Portable fire-arms, 290; early history Ores of iron, used for the manufacture of, 273; calibre of, 293. of cannon, 146. Port-fires, composition of, 359. Ornamental fireworks, 376. Position of the centre of gravity of projectiles, 178. Pack-horse, work of, to be regulated, Pot of signal-rokets, 367. 212. Potassa, chlorate of, used in the manuPacking gunpowder, 30; arms, 330; facture of gunpowder, 14; in pyrosmall-arm cartridges, 349. techny, 344. "Packing the joint " of breech-loading Powder, proper charge of, for elongated arms, 302. bullets, 314; see Gaunpowder. Painting artillery carriages, 268. Powder, round, 25. Palliser guai, 547; projectiles, 473-561. Powder-proof of cannon, 205. Paper, laboratory, classes of, 347. Practical rule for initial velocity, 387. Paper shells, how made, 380. Prairie artillery carriage, description Parrott rifle-gun, how constructed, 548; of, 238. ranges of, 527, 529. Prairie-cannon, 183. Parrott's rifle projectile, 557. Precaution in using fire-arms, 336; Parsons gun, 548. against accidents in pyrotechny, 343; Pass-box, for carrying cartridges, 252. in loading cannon, 435. Patch, mode of using with rifles, 308. Preponderance of cannon, 161; mortars Pattern for moulding cannon, 195. and columbiads now made without Pendulum hausse, how used, 255. (note), 162; of the siege-howitzer, 186. Penetration of projectiles, 476,544, 545; Preservation of gunpowder, 34; of of the rifle-musket bullet, 486, 546. cannon-balls, 93; of artillery harPercussion bullets, how made, 83. ness, 219; of artillery carriages, 259; Percussion-caps, description of, 350. of timber, 265; of arms in service, Percussion-fuze, description of, 365. 332. Percussion-lock, nomenclature of, 296. Pressure in the bore of the 15-inch Perriere, an early form of cannon, 105. columbiad, 542. Petard, explosive, thrown aside, 376. Priming-wire, for pricking cartridges, Petard, in ornamental fireworks, 377. 253. Petronel, description of the, 274. Pritchett bullet, how made, 313. Pig-iron, character of, 146; density and Projectile arms, ancient, 271. tenacity of, 147. Projectile force of gun-cotton, 69. Pike, the ancient, 270. Projectiles, materials of, 71; advan-,Piling of cannon-balls, 93. tages of spherical, 73; centre of Pintle, the centre of the chassis of sea gravity of, 74; oblong, superiority of coast gun-carriages, 246. the form of, 74; solid, for what purPintle-hook of the field-limber, 232. poses adapted, 75; fabrication of, Pistol, when and where invented, 274. 88; hollow, cavities of, how made, Pistol-carbine, description of, 318. 89; inspection of, 90; maximum vePistol cartridge, how made, 350. locity of, on what dependent, 129; prQPitch in pyrotecliny, 347. portion of, to weight of charge, 131; Pitched fascines, for incendiary pur- with flanges, for rifles, 168; conposes, 374. structed on an expanding principle, Plane of fire, definition of, 437. 169; effect of length of, 175, infiuPlane of rupture of shells, 84. ence of the resistance of the air upon, Plane of sight, definition of, 437. 177; effect of the position of -the Platforms of siege pieces, how con- centre of gravity of, 178; shells and structed, 24.1. hot-shot the best for sea-coast batPlunging-fire, 459. teries, 189; injuries to cannon from, Point-blank, definition of, 437. 209; for small-arms, 307; of the Pointing fire-arms, 435. Whitworth rifle, 311; initial vePointing guns, implements for, 254. locity of, 383; fall of, in the air, 404; Pointing small-arms, 445. theory in relation to the form of, Pole of the field-limber, 231. 409; oblong, trajectory of, 423; de INDEX. 581 viation of, 424; concentric, effect of practical rules for, 453; of field arrotation on, 427; eccentric, effect of tillery, 492; of sea-coast batteries, rotation on, 427; oblong, deviation 504. of, 43 t1; smaller than the bore, how Ricochet firing, cartridge-bag for, 354. used, 435; effects of, 471; of the Rifle-cannon, hardness of metal necesArmstrong gun, 528. sary to, 137; definition of, 167; Projections, omitted on the surface of breaching with, 485. cannon of late construction, 160. Rifled fire-arms, form of groove of, 171; Prolonge, a stout hempen rope. 258. variable groove of, 172; limit of inProof of gunpowder, 27; of cannon, clination of grooves in, 179. 205; of sword-blades, 289; of scab- Rifle-grooves, points to be observed in bard, 290. constructing, 294. Properties of bronze, 139; of steel, 142. Rifle-guns, ranges of, 522. Props of chassis rails, 247. Rifle-musket, description of the, 316; Puddled steel, how obtained, 142. how dismounted, 332; trials of Pulverizing charcoal, 23. strength of, 340: cartridge, 349; Pyrotechny, definition of, 342; build- bullet, penetrations of, 486. ings for, 342; precautions against Rifle-projectiles, different systems of, accidents in, 343; materials for 344- 545. 348. Rifle siege-gun, description of (note), Pyroxile, or gun-cotton, 68. 184. Rifles, how classified, 168; invention Quadrant, gunner's, 256. and history of the, 275; original Queen Anne's pocket-piece, 100. mode of loading, 308; as distinQuick-match, description of, 359. guished from the rifle-musket, 317; American sporting, 319. Rail platform, how constructed, 242. Rimbases of cannon, 116; description Rammer-head used in the inspection of, 162. of cannon, 201. Robins, elongated projectiles proposed Rammer-head for loading cannon, by, 309; on the path of. projectiles, 251. 383; deviation by rotation discovRampart grenade, 79. ered by, 431. Ramrods of portable fire-arms, 301; Rockets, theory and construction of, inspection of, 329. 94; motion of, 95; origin of moveRange, to determine, 422; definition ment in, 96; guiding principle of, of, 439. 97; Hale's system for guiding, 98; Range of field artillery, 462, 463, 488; Congreve's system for guiding, 99; of siege cannon, 493; of the Arm- how fired, 99; signal and war, 99; strong projectile, 530; of artillery, form of trajectory of, 100; effect of 516-523. wind on the trajectory of, 101; hisRanges,table of values for calculation tory of, 102; advantages claimed for, of, 507, 513. over cannon, 102; kinds used in the Ranges of mortar-shells, table of, 401. United States service, 103; signal, Ranges obtained with Captain Rod- principal parts of, 366. man's 15-inch columbiad, 524. Rodman, General, experiments of, with Rapidity of fire, 448. cake-powder (note), 49; experiments Rear-sight of portable fire-arms, 299; of, in relation to the density of gases aiming without, 300. (note), 58; plan of, for cooling canRear-sights, graduation of, 445. non from the interior, 136; plan of, Recoil, increase of, greater than in- for determining the force of the crease of charge, 130; diminished charge in fire-arms, 152; experiby application of weights, 137. inents of, on the force of cake and Reinforce of cannon, 115. grained powder (note), 153; his forRejected cannon, how marked, 207. mula for calculating the exterior Repairs of artillery carriages, 259. form of large cannon (note), 157; Remaining velocities, table of, 543. great improvements of, in casting Resistance of the air, 402; effect of, on large guns, 552. a rifle-projectile, 177; loss of velocity Roller handspike, for new sea-coast by, 406. carriages, 257. RItempering a sword-blade, 288. Rolling fire, 458. Ricochet fire, 450; when used, 452; Rolling friction, 223. 582 INDEX. Rolling musket-barrels, 321. Sea-coast howitzers, description of, Roman candles, how made, 380. 193; ranges of, 519. Rope matting impenetrable to small- Sea-coast howitzer shell. 79. arm projectiles, 487. Sea-coast mortars, description of, 193; Rosin in pyrotechny, 347. the new, 194; ranges with the 13Rotation, initial velocity of, in rifle- inch, 541. projectiles, 174; a principal cause of Sea-coast shells, range and force of, deviation of projectiles, 42,5: effect 464. of, in producing deviation, 427; of Searcher, 201. the earth, influence of; in producing Seasoning and preserving timber, 265. deviation, 434. Seat of the charge of cannon, 120. Round bullets, denomination of, 76. Second reinforce, thickness of, 158. Round powder, how made, 25. Self-priming percussion-lock, MayRules for firing to effect a breach, 484. nard's, 297. Rules for ricochet fire, 453. Serpents in fireworks, how composed, Rumford, Count, experiments of, on 368. the combustion of gunpowder, 54; Sharp's system of " packing the joint" eprouvette used by, for determining of breech-loading arms, 303. the force of gunpowder, 55. Shear-steel, various kinds of, 141. Rupture of cannon, tendency to, great- Shell-hooks, 254. est from tangential force, 156. Shell-plug screw, 253. Rupture of shells, 84. Shells, material and denomination of, 77; spherical, description of, 78; Sabot, description of the, 351. charge of rupture of, 84; loss of gas Sabre, the ancient,.271; best construc- by the fuze-holes of, 87; strapped to tion of for handling, 283; descrip- sabots, 354; service bursting-charges tion of, 284. of, 355; loaded as carcasses, 372; Saddle of the artillery horse, 218. paper, how made, 380; French morSaltpetre, description of, 9; whence tar, table of times of flight of, 401; obtained, 10; test of rough, 133; test force and range of, 463. of pure, 14; quantity of, in gunpow- Shod handspike, for mortars, 257. der, 31. Shot, inspection of, 90; for proving Sand, the best kind for moulding can- cannon, 206; wedged in cannon, how non, 196. drawn out, 261. Sarissa, or Macedonian lance, 270. Shrapnel, Colonel, spherical case-shot Sawyer's rifle-projectile, 559. perfected by, 82. Saxon, in movable fireworks, 379. Shrapnel firing, 465. Scabbard, uses and material of the,. Siege and sea-coast ammunition, 353. 285; proof of, 290. Siege-cannon, 184; rapidity of fire of, Schenkle's rifle-projectile, 558. 449; employment of; 493. SchOnbein, Prof., gun-cotton discover- Siege-carriages, various kinds of, 239. ed by, 68. Siege gun-carriage, construction of, Schwartz, Berthold, explosive proper- 239. ties of gunpowder discovered by, Siege-guns, characteristics of, 184; 36. ranges of, 518. Science of gunnery, 382. Siege-howitzer, description of, 186; fire Scratches in cannon, 210. of, in attack or defence, 497; ranges Screw-jack, used in greasing carriage- of, 519. wheels, 259. Siege-mortars, description of, 186; bed, Scott projectile, 557. how constructed, 241; ranges of, Sea-coast ammunition, 353. 520. Sea-coast cannon, 188; various kinds Siege-shells, uses of, 464. of, 190; rapidity of fire of, 449; em- Sights of portable fire-arms, 298. ployment of, 502. Signal-rockets, 99; principal parts of, Sea-coast carriages, classification of, 366. 243; various kinds of, 247. Signals, fireworks for, 366. Sea-coast defence, fires advantageous Sinope, destruction of the Turkish fleet in: 503. at, by Russian shells, 189. Sea-coast fuze, description of, 363. Skelp of a sword-blade, 287. Sea-coast gun-carriages, 243. Sky-rockets, 378. Sea-coast guns, ranges of, 519. Sleeves, gunner's, 254. INDEX. 5853 Sling, the ancient, 271. Storehouse for artillery harness, 219. Sling-carts, wooden and iron, 249. Straightening plates of musket-barrels, Slow-match, description of, 358. 821. Small-arm firing, 469. Straight sword, parts of, 278. Small-arm projectiles, 307. Strain upon cannon, various kinds of, Small-arms, classification of, 268; 154. charge of powder for, 314; different Strapped ammunition, 353. kinds of, 316; manufacture of, 320; Strapping shells described, 354. inspection of, 327; ammunition for, Straps of a stand of ammunition, 352. 348; trajectory of projectiles of, 414, Strength of cannon, effect of form of 418; rapidity of fire of, 449; how chamber on, 124. pointed, 445. Strength of material of cannon, 132, Soda, nitrate of, 15. 134. Solid-shot, classification of, 75; pene- Strength of musket-barrels, 340. trations of, 478; when broken, 478, Strength of wrought-iron, 143. 481. Structure of rockets, 94. Solid-shot firing, 462. Sulphur, purification of, 20; properties Solubility of nitre, 9. of, 20; quantity of, in gunpowder, Sparks in fireworks, how produced, 32; the tenacity of cast-iron destroy346. ed by, 149; in pyrotechny, 345. Spherical case-shot, description of, 82; Sulphuret of antimony in pyrotechny, fabrication of, 88; for mortars, 188; 345. late improvements in, 466; effect of, System of artillery, 108. from rifle-cannon, 467. Swaging, in the process of making Spherical chamber of fire-arms, 123. musket-barrels, 323. Spherical projectiles, advantages of, Sweden, peculiar form of cast-iron can73. non cast in, 159. Spherical shells, description of, 78. Swell of the muzzle of cannon, 115; Spiking cannon, process of, 260. thickness of, 159. Spirits of turpentine in pyrotechny, Swiss service bullet, 314. 347. Sword, the ancient, 271. Splinter-bar of the field-limber, 231. Sword, the straight, parts of, 278. Sponge, for cleaning out cannon, 251. Sword-bayonet, description and uses Sponge-bucket, for washing bore of of the, 281. cannon, 258. Sword-blades, manufacture of, 287. Spontoon, or half-pike, 271. Sporting rifle, American, 319. Table of initial velocities with serviceSpringfield, Mass., United States Ar- ~ charges, 387. mory at, 320. Tables of fir6, 516; purpose of, 447. Sprue, used in casting cannon, 196. Tables of multipliers, 505. Stand of ammunition, how composed, Tangential strain upon cannon, 154. 331. Tangent-scale, how used in pointing Star-gauge, 200. guns, 255. Stars of signal rockets, 367. Tar in pyrotechny, 347. Steamer Princeton, why the large Tar-bucket, for carrying grease, 258. wrought-iron gun burst on, 144. Targets, construction of, 461. Steel as a material for cannon, 139; Tarred-links, how made and used, 374. characteristics of, 140; properties of, Tartaglia on the path of projectiles, 142; Damascus, how made, 287; 382. how: hardened and tempered, 326. Telescopic sights of fire-arms, 299. Steel plates and iron, comparative re- Temperature, importance of, in the sistance of, to projectiles, 474. manufacture of charcoal, 17. Stick of signal rockets, 369. Temperature of the gaseous products Stock of an artillery carriage, 225. of gunpowder, 54. Stock of portable fire-arms, 298; de- Tempering steel, 326. fects in, 338; inspection of, 329. Tempering sword-blades, 287. Stock trail system of artillery, 112. Tenacity of bronze, 139. Stone mortar, uses and dimensions of, Tenacity of puddled steel, 142. 187; charge of, 465. Theory and construction of rockets, Stone projectiles, 71. 94. Storage of gunpowder, 34; arms, 331. Thickness of the metal of cannon, 151. '584 INDEX. Thouvenin, form of projectile proposed Uniform groove in rifled fire-arms by, 309. 171. Thrusting arms, 277, 284. United States service bullet, 312. Thumbstall, for closing vent, 253. Unspiking cannon, process of, 261. Tige, or spindle, of Colonel Thouvenin, Uses to which cannon are applied, 310. 180. Tilted steel, 141. Timber, for artillery carriages, 261- Valiere's sytem of artillery, 110. 266; seasoning and preserving, 265. Values, tables of, 510-514. Time-fuze, description of, 360. Variable groove in rifled fire-arms. Times, table of, for West Point ballis- 172. tic machine, 515. Vauban's method of breaching walls, Tin, bronze cannon injured by the 482. melting of the, 139. Velocities and times, tables of values Torches, preparation and use of, 375. of, 129, 512. Tourbillion, description of the, 379. Velocity, initial, of projectiles, 383; Track of field carriages 233. maximum of,. dependent on what, Trail handspike for field carriages, 256. 129; loss of, by resistance of the Trajectory of rockets, 100; of projec- air, 406; causes affecting, 424. tiles, ancient theory respecting, 382; Velocity of combustion of gunpowder, in the air, 412-424; under high an- 39. gles of projection, 420; of oblong Venice turpentine in pyrotecllny, 347. projectiles, 423; true and calculated, Vent, small loss of force by the escape 423. of gas through, 119; table illustratTransportation of gunpowder, 35. ing influence of position of, 119. Transverse strain upon cannon, 155. Vent of Armstrong gun, 528. Travelling-forge, description of, 236. Vent of cannon, position of, 117; size Treadwell, Prof., plan of, for combin- of, 117; how bored, 200; inspection ing wrought-iron and cast-iron in of, 204; wear of, how obviated, 208 cannon, 150. Vent of fireworks, 358. Trees, selection of, for timber for artil- Vent of rockets, 95. lery purposes, 263; defects of tim- Vent-gauges, 201. ber, 265. Vent-piece, copper, adopted for rifle Trench-cart, for use in trenches. 251. guns (note), 117. Trigger of portable fire-arms, 300. Vent-searcher, 201. Trituration, influence of, on the com- Vertical field of fire of field-guns, 181; bustibility of charcoal, 19; effect of, of siege-guns, 185; of siege-mortars, on the ingredients of gunpowder, 187; of the new columbiad, 192. 43. Trunnion-gauge, 201. Wade, Major, experiments of, with.Trunnion-rule, 201. eccentric shells, 430. Trunnion-square, 201. Wads (junk, hay, and ring), how used, Trunnions of cannon, 115; description 355. of, 160; influence of position of, on Wagon, battery, 236. recoil, 160; size of, dependent on War-club, ancient, 270. recoil, 160; importance of position War-powder, proportions ofingredients of, on siege and sea-coast cannon, of, in the United States service, 53. 162; verification of the axis of, 203. War-rockets, 99. Trunnions of the siege-howitzer, 186. Water, penetration of projectiles into, Truck for moving cannon in case- 480. mates, 250. Watering bucket, artillery, 258. Truck handspike, for sea-coast car- Weapons, ancient defensive, 272. riages, 257. Weight, recoil diminished by, 137. Tube-pouch, worn by a cannonier, 252. Weight of American small-arms, 316Turning cannon, 199; musket-barrels, 319. 324. Weight of barrel of portable fire-arms, Turning of field-carriages, 232. 291. Turpentine in pyrotechny, 346. Weight of cannon, how determined, Twist, the inclination of a rifle-groove, 165. 171. Weight of field-guns and howitzers, 180. INDEX. 5S5 Weight of projectile and powder of Willow, charcoal for gunpowder made American small-arms, 316-319. froml, 15. Weight of siege-guns, 185. Wind, deviation caused by, 433; effect Welding, description of the process of, of, on the trajectory of rockets, 101. 321. Windage, loss of force from, 124. Welding plates for musket-barrels, Wood, effect of projectiles on, 474; 321. penetrations of projectiles into, 479. West Point ballistic machine, 390- Wootz, a natural steel from India, 140. 395; table of times calculated for, Worm, for withdrawing cartridges, 515. 252. Wheels of artillery carriages, names Wounds made by thrusting-swords, of parts of, 220; objects of, 221; in- 279. fluence of size of, 224; greased and Wrought-iron, projectiles of, 72; as a ungreased, 227; should be of the material for cannon, 143; for artilsame height, 233. lery carriages, 266; effect of projecWheels ot gun-carriages, weight of, tiles on, 472. 224; should be few kinds of, Wrought-iron cannon made by the 224. Phoenix Iron Co., 181. White iron, characteristics of, 148. White pine, effect of projectiles on, Yataghan of the Arabs, 283. 475. Whitworth rifle-gun, 544; projectiles, Zorndorf, effect of a field-cannon ball 556. at the battle of, 487. D. Van Nostrand's Publications. Barre Dupareq's Military Art and History. Elements of Military Art and Historyv comprising the History and Tactics of the separate Arms; the Combination of the Arms; and the minor operations of War. By EDWARD DE LA BARRE DUPARCQ, Chef de Bataillon of Engineers in the Army of France; and Professor of the Military Art in the Imperial School of St. Cyr. Translated by Brig.-Gen. GEO. W. OULLUM, U. S. A., Chief of the Staff of Major-Gen. H. W. HALLECK, GenDralin-Chief U. S. Army. 1 vol. 8vo, cloth. $5.00.'I read the original a few years since, and considered it the very best work I had seen upon the subject. Gen. Cullum's ability, and familiarity with the technical language of French military writers, are a sufficient guarantee of the correctness of his translation." H. W. HALLECK, Major-Gen. U. S. A. Benet's Military Law. A Treatise on Military Law and the Practice of Courts-Martial. By Capt. S. V. BENET, Ordnance Department, U. S. A., late Assistant Professor of Ethics, Law, &c., Military Academy, West Point. Fifth edition, revised. 1 vol. 8vo, law sheep. $4.50. "This book is manifestly well timed just at this particular period, and it is, without doubt, quite as happily adapted to the purpose for which it was written. It is arranged with admirable method, and written with such perspicuity, and in a style so easy and graceful, as to engage the attention of every reader who inay be so fortunate as to open its pages. This treatise will make a valuable addition to the library of the lawyer or the civilian; while to the military man it seems to be indispensable."-Philtadelphia Evening Journal. Halleck's International Law. International Law; or, Rules Regulating the Intercourse of States in Peace and War. By Major-Gen. i H. W. HALLECK, Commanding the Army. 1 vol. 8vo, law sheep. $6.00. "The work will be found to be of great use to army and navy officers, to professional lawyers, and to all interested in the topics of which it treats-topics to which present events give a greatly enhanced importance-such as'Declaration of War and its Effects;'' Sieges and Blockades;'' Visitation and Search;'' Right of Search;'' Prize Courts;'' Military Occupation;''Treaties of Peace;''Sovereignty of States,' &c., and valuable information for consuls and ambassadors."-N. Y. Evening Post. History of West Point. And its Military Importance during the American Revolution; and the Origin and Progress of the United States Military Academy. By Capt. EDWARD C. BOYNTON, A. M., Adjutant of the Military Academy. With numerous Maps and Engravings. 1 v l. 8vo, blue cloth, $6.00; half mor., $7.50; full mor., $10.00. "It records the earliest attempt at instituting a Military School by the Continental Congress, in 17T6. It conducts us through the life of the institution, arguing with terseness its constitutionality, defending its educational principles,kand explaining the necessity for its preservation." — Uited Service Acsagazin. i.. i D. Van 2Nrostrand's Publications. History of the United States Naval Academy. With Biographical Sketches, and the Names of all the Superintendents, Professors, and Graduates; to which is added a Record of some of the earliest votes by Congress, of Thanks, Medals, and Swords to Naval Officers. By EDWARD CHAUNCEY MARSHALL, A. M. 1 vol. 12mo, cloth, plates. $1.00. "Every naval man will find it not only a pleasant companion, but an invaluable book of reference. It is seldom that so much information is made accessible in so agreeable a manner in so small a space."-New York Times. Scott's Military Dictionary. Comprising Technical Definitions; Information on Raising and Keeping Troops; Actual Service, including Makeshifts and improved Materiel and Law, Government, Regulation, and Administration relating to Land Forces. By Colonel H. L. Scott, Inspector-General U. S. A. 1 vol. large octavo, fully illustrated, half morocco, $6; half russia, $8; full morocco, $10. "This book is really an EncylopTedia, both elementary and technical, and as such occupies a gap in military literature which has long been most inconveniently vacant. This book meets a present popular want, and will be secured not only by those embarking in the profession but by a great number of civilians, who are determined to follow the descriptions and to understand the philosophy of the various movements of the Campaign. Indeed, no tolerably good library would be complete without the work." —New York Times. Benton's Ordnance and Gunnery. A Course of Instruction in Ordnance and Gunnery; compiled for the use of the Cadets of the United States Military Academy. By Capt. J. G. Benton, Ordnance Department, late Instructor of Ordnance and Gunnery, Military Academy, West Point; Principal Assistant to Chief of Ordnance, U. S. A. Third Edition, revised and enlarged. 1 vol. 8vo, cloth, cuts. $5.00. "There is no one book within the range of our military reading and study, that contains more to recommend it upon the subject of which it treats. It is as full and complete as the narrow compass of a single volume would admit, and the reputation of the author as a scientific and practical artillerist is a sufficient guarantee for the correctness of his statements and deductions, and the thoroughness of his labors." —V. Y. Observer. Gibbon's Artillerist's Manual. Compiled from various Sources, and adapted to the Service of the United States. Profusely illustrated with woodcuts and engravings on stone. Second edition, revised and corrected, with valuable additions. By Gen. John Gibbon, U. S. A. 1 vol. 8vo, half roan. $6.00. This book is now considered the standard authority for that particular branch of the Service in the United States Army. The War Department, at Washington, has exhibited its thorough appreciation of the merits of this volume, the want of which has been hitherto much felt in the service, by subscribing for 700 copies. 2 D. Van Niostrand's Publications. Jomini's Life of the Emperor Napoleom 1. Life of Napoleon. By Baron Jomini, General-in-Chief and Aide-de-Camp to the Emperor of Russia. Translated from the French. with Notes, by H. WV. Halleck, LL. D., Major-General United States Army; author of "Elements of Military Art and Science," " International Law, and the Laws of War,' etc., etc. In four volumes octavo, with an Atlas of Sixty Maps and Plans. Price, in red cloth, $25.00; half calf, or half moro'xio, $35.00; half russia, $37.50.' It is needless to say any thing in praise of Jomini as a writer on the science of war. "General Halleck has laid the professional soldier and the student of military history under equal obligations by the service he has done to the cause of military literature in the preparation of this work for the press. His rare qualifications for the task thus undertaken will be acknowledged by all. "The Notes with which the text is illustrated by General Halleck are not among the least uif the merits of the publication, which, in this respect, has a value not possessed by the original work. * * *' — National Intelligeacer. "The Atlas attached to this version of Jolnini's Napoleon adds very materially to its value. It contains sixty Maps, illustrative of Napoleon's extraordinary military career, beginning with the immortal Italian Campaigns of 1796, and closing with the decisive Camlpaign of Flanders, in 1815, the last Map showing the Battle of Wavre. These Maps take the reader to Italy, Egypt, Palestine, Germany Moravia, Russia, Spain, Portugal, and Flanders; and their number and variety, and the;ast and various theatres of action which they indicate,:testify to the immense extent of Nai;oleon's operations, and to the gigantic character of his power. * * *" -Boston Traveller ~ Jomini's Grand M[ilitary Operations. Treatise on Grand Military Operations; or, a Critical and Military History of the Wars of Frederick the Great, as contrasted with the Modern System, together with a few of the most important Principles of the Art of War. By Baron Jomini, General-in-Chief and Aide-de-Camp to the Emperor of Russia. Translated from the French by Col. S. B. Hiolabird, A. D. C. U. S. A. 2 vols. 8vo, cloth, with an Atlas of 40 Maps and Plans. $15.00. Jomnini's Campaign of Waterloo. The Political and Military History of the Campaign of Waterloo. Translated from the French of General Baron de Jomini, by Capt. S. V. Bendt, Ordnance Department, U. S. Army. Third edition. 1 vol. 12mo, cloth, $1.25. "Baron Jomnini has the reputation of being one of the greatest military historians and critics of the century. His merits have been recognized by the highest military authorities in Europe, and were rewarded in a conspicuous Inanner by the greatest military power in Christendom. He learned the art of war in the school of experience, the best and only finishing school of the soldier. He served with distinction in nearly all the campaigns of Napoleon. and it was mainly from the gigantic military operations of this matchless matster of the art that he was enabled to discover its true principles, and to ascertain the best means of their application to the infinlty of combinations which actual war presents. Jomnini criticises the details of Waterloo with great science, and yet in a manner that interests the general reader as well as the professional."-New York World. 3 D. Van Nostrand's Publications. Roeiner's Cavalry; its History, Malanagemenut, and Uses in War. By J. Roemer, LL. D., late an Officer of' Cavalry in the Service of the Netherlands. Elegantly illustrated, with one hundred and twenty-seven fine wood engravings. In one large octavo volume, beautifully printed on tinted paper. Cloth, $6; half calf, $7.5(0. "By far the best treatise upon Cavalry and its uses in the field, which has yet been published in this country, for the general use of officers of all ranks, is this elaborate'and interesting work. Eschewing the elementary principles and tactics of cavalry, which may be learned from any hand-book, the author treats of the uses of cavalry in the field of strategy and tactics, and of its general discipline and management. The range of the work includes an admirable treatise upon rifled fire-arms, an historical sketch of cavalry, emnbodying many interesting facts, an account of the cavalry service in Europe and this country, and a treatise on horses, their equipment, management, &c. The work is copiously illustrated and elegantly printed. It is interesting not alone to military men but to the general reader, who will gain from its pages valuable historical facts and very clear ideas of some branches of the art of war, such as the employment of spies, gaining information in an enemy's country, advance movements, and other strategical mateuvres." — Boston Journal. Nolan's System for Training Cavalry Horses.. By Kenner Garfard, Captain Fifth Cavalry, U. S. A. 1 vol. 12mo, cloth. 24 lithographed plates. $2.00. "This work is clearly written, is eminently practical, is fully illustrated, and contains numerous hints as applicable to the discipline and management of the draught-horse as that ofNis more showy and fiery brother of the cavalry."-Boston Journzal. Barnard and Barry's Peninsular Campaign. Report of the Engineer and Artillery Operations of the Army of the Potomac, from its organizatiQn to the close of the Peninsular Campaign. By Brig.-Gen. J. G. Barnard, and other Engineer Officers, and Brig.-Gen. W. F. Barry, Chief of Artillery. Illustrated by numerous Maps, Plans, etc. 1 vol. 8vo, cloth, $4.00. "The title of this work sufficiently indicates its importance and value as a contribution to the history of the great rebellion. General Barnard's IReport is a narrative of the Engineer operations of the Army of the Potomac from the time of its organization to the date it was withdrawn from the Janmes River. Thus a record is given of an inlportant part in the great work which the nation found before it when it was first confronted with the necessity of war; and- perhaps on no other point in the annals of the rebellion will future generations look with a deeper or more admiring interest."-Bueffalo Coserier. The "C. S. A.," and the Battle of Bull Run. (A Let. ter to an English friend), by J. G. Barnard, Lieut.-Colonel of Engineers, U. S. A., Brigadier-General and Chief Engineer, Army of the Potomac. With five Maps. 1 vol. 8vo, cloth. $2.00. "The work is clearly written, and can but leave the impression upon every reader's niund that it is truth. We commend it to the perusal of every one who wants an intelligent, truthful, and graphic description of the'C. S. A.,' and the Battle of Bull Run."cNAw York Observer. ~.~__ 4 D). Van Nostrand's Publications. Simpson's Ordnance and Naval Gunnery. A Treatise on Ordnance and Naval Gunnery, compiled and arranged as a Text-Book for the U. S. Naval Academy. By Lieut. Edward Simpson, U. S. N. Third edition, revised and enlarged. i vol. 8vo, plates and cuts, cloth. $5.00. ".'; a scarcely necessary for us to say, that a work prepared by a writer so practically cJ-,fersant with all the subjects of which he, treats, and who has such a reputation for scientific ability, cannot fail to take at once a high place among the text-books ot our naval service. It has been approved by the Secretary of the Navy, and will henceforth be one of the standard authorities on all matters connected with Naval Gunnery."-N-ew York Herald. Holley's Ordnance and Armor. Embracing Descriptions, Discussions, and Professional Opinions concerning the Material, Fabrication, Requirements, Capabilities, and Endurance of European and American Guns for Naval, Sea-Coast, and Iron-Clad Warfare, and their Rifling, Projectiles, and Breech-Loading; also, Results of Experiments against Armor, from Official Records. With an Appendix, referring to GunCotton, Hooped Guns, etc., etc. By A. L. Holley, B. P. With 493 illustrations. 1 vol. 8vo, 948 pages. Half roan, $10.00. Luce's Naval Light Artillery. Instructions for Naval Light Artillery, afloat and ashore, prepared and arranged for the U. S. Naval Academy, by Lieutenant W. H. Parker, U. S. N. Second edition, revised by Lieutenant S. B. Luce, U. S. N., Assistant Instructor of Gunnery and Tactics at the U. S. Naval Academy. 1 vol. 8vo, cloth, with twenty-two Plates. $3.00. "The service for which this is the text-book of instruction is of special importance in the present war. The use of light boat-pieces is constant and important, and young officers are frequently obliged to leave their boats, take their pieces ashore, and inlanceuvre them Ms field artillery. Not unfrequently, also, they are incorporated, when ashore, with troops, and must handle their guns like the artillery soldiers of a battery.' The Exercise of the Howitzer Afloat' was prepared and arranged by Captain Dahlgren, whose name gives additional sanction and value to the book. A Manual for the Sword and Pistol is also given. The Plates are numerous and exceedingly clear, and the whole typography is excellent."-Philadelphia Inquirer. Ward's Naval Ordnance and Gunnery. Elementary Instruction in Naval Ordnance and Gunnery. By James H. AWard, Commander U. S. Navy; author of "Naval Tactics," and "Steam for the Million." New edition, revised and enlarged. 8vo. cloth. $2.00. "It conveys an amount of information in, the same space to be found nowhere else, and given with a clearness which renders it useful as well to the general as the professional lnqnirer."-N. Y. Evening Post. "The whole detail of Ordnance, in ts history, philosophy, and appllication. s given by Comrmander Wnard in such a manner (with occasional diagrams)j as to convey to the student accurate notions for practical use." —New Yorker. 5 _ A......................................-. D. Van Nostrand's Publications. LuIce's Seamanship. Compiled from various authorities, and Illustrated with numerous original and selected Designs. For the use of the United States Naval Academy. By S. B. Luce, Lieut.-Commander U. S. N. In two parts. Second Edition. One royal octavo volume, cloth. $10.00. Squadron Tactics Under Steam. By Foxhall A. Parker, Commander U. S. Navy. Published by authority of the Navy Department. 1 vol. 8vo, with numerous Plates. $5.00. "In this useful work to Navy officers, the author demonstrates-by the aid of profuse diagrams and explanatory text-a new principle for maneuvring naval vessels in action. The author contends that the win(ls, waves, and currents of the ocean oppose no more serious obstacles to the movements of a steam fleet, than do the inequalities on the surface of the earth to the raneuvlres of an army. It is in this light, therefore, that he views a vast fleet-simply as an army; the regiments, brigades, and divisions of which are represented by a certain ship or ships."-Scienzt/fic American. Nautical Routine and Stowage. With Short Rules in Navigation. By John McLeod Murphy and Wm. N. Jeffers, Jr., U. S. Navy. 1 vol. 8vo, blue cloth. $2.50. Osbon's Hand-Book of the United States Navy. Being a Compilation of all of the Principal IEvents in the History of every Vessel of the United States Navy, from April, 1861, to May, 1864. Compiled and arranged by B. S. Osbon. 1 vol. 12mo, blue cloth. $2.50. "As a condensed and compact history, as well as a work containing a vast amount of information, this work cannot be surpassed."-Boston Traveller. Brandt's Gunnery Catechism. Gunnery Catechism, as applied to the Service of Naval Ordnance. Adapted to the Latest Official Regulations, and approved by the Bureau of Ordnance, Navy Department. By J. D. Brandt, formerly of the U. S. Navy. 1 vol. 18mo, illustrated, blue cloth. $1.50. "This manual is very full of information and instruction, and shows the' chief end' of Gunnery, and the aim of those who follow that profession. It is indispensable to all those who are suddenly introduced to a gun-deck, and will be found a valuable aid also to experienced officers." —Commercial Advertiser. Barrett's Gunnery Instructions. Gunnery Instructions, simplified for the Volunteer Officers of the United States Navy, with Hints to Executive and other Officers. By Lieut. Edward Barrett, U. S. N., Instructor of Gunnery, Navy Yard, Brooklyn. 1 vol. 12mo, cloth. $1.25. "It is a thorough work, treating plainly on its subject, and contains also some valuable hints to executive officers. No officer in the volunteer navy should be without a co} y'"-Boston Evening Traveller. 6 D. Van Nostrand's Publications. Totten's Naval Text-Book. Naval Text-Book and Dictionary, compiled for the use of the Midshipmen of the U. S. Navy. By Com mander B. J. Totten, U. S. N. Second and revised edition. 1 vol. 12mo. $3.00. Calculated Tables of Ranges for Navy land Army Guns. With a Method of Finding the Distance of an Object at Sea. By Lieut. W. P Buckner, U. S N. 1 vol. 8vo, cloth. $1.50. Manual of Internal Rules and Regulations for Menof-War. By Commodore U. P. Levy, U. S. N., late Flag Officer cornmanding U. S. Naval Force in the Mediterranean, &c. Flexible blue cloth. Third Edition, revised and enlarged. 50 cents. "Among the professional publications for which we are indebted to the war, we willingly give a prominent place to this useful little Manual of Rules and Regulations to be observed on board of ships of war. Its authorship is a sufficient guarantee for its accuracy and practical value; and as a guide to young officers in providing for the discipline, police, and sanitary government of the vessels under their command, we know of nothing superior."-.'. Y. IIerald. King's Lessons and Practical Notes on Steam, The Steam Engine, Propellers, &c., &c., for Young Marine Engineers, Students, and others. By the late W. H. King, U. S. Navy. Revised by Chief Engineer J. W. King, U. S. Navy. Ninth Edition, enlarged. 8vo, cloth. $2.00. "This'is the ninth edition of a valuable work of the late W. H. King, U. S. Navy. It contains lessons and practical notes on Steain and the Steaml-Engine. Propellers, &c. It is calculated to be of great use to young marine engineers, students, and others. The text is illustrated and explained by numerous diagrams and representations of machinery. This new edition has been revised and enlarged by Chief Engineer T. W. King, U. S. Navy, brother to the deceased author of the work."-Boston Dlily Advertiser. Ward's Steam for the Million. A popular Treatise on Steam and its Application to the Useful Arts, especially to Navigation. By J. H. Ward, Commander U. S Navy. New and revised Edition. I vol. 8vo, cloth. $1.00. The Naval Howitzer Ashore. By Foxhall A. Parker, COrn. mander U. S. Navy. 1 vol. 8vo, with Plates. Cloth. $4.00. 7 D. Van NVostrand' s Publications. Gillmore's Fort Sumter. Official Report of Operations against the Defences of Charleston Harbor, 1863. Comprising the Descent upon Morris Island, the Demolition of Fort Sumter, and the Siege and Reduction of Forts Wagner and Gregg. By Major-Gen. Q. A. GILLEORE. U. S. Volunteers, and Major U. S. Corps of Engineers. With Maps and Lithographic Plates, Views, &c. 1 vol. 8vo. cloth. $10. Gillmore's Siege and Reduction of Fort Pulaski, Georgia. Papers on Practical Engineering. No. 8. Official Report to the U. S. Engineer Department of the Siege and Reduction of Fort Pulaski, Ga., February, March, and April, 1862. By Brig.-Gen. Q. A. GILMORE, U. S. A. Illustrated by Maps and Views. 1 vol. 8vo, cloth. $2.50. "This is an official history of the siege of Fort Pulaski, from the commencement, with all the details in full, made up from a daily record, forming a most valuable paper for future reference. The situation and construction of the Fort, the position of the guns, both of the rebels and the Federals,' and their operation, are made plain by maps and engraved views of different sections. Additional reports from other officers are furnished in the appendix, and every thing has been done to render the work full and reliable."-Bostose Jowrieal. Gillmore's Treatise on Limes, Hydraulic Cements, and Mortars. Papers on Practical Engineering, U. S. Engineer Department, No. 9, containing Reports of numerous Experiments conducted in New York City, during the years 1858 to 1861, inclusive. By Q. A. GILLMORE, Brig.-Gen. U. S. Volunteers, and Major U. S. Corps of Engineers. With numerous Illustrations. One vol. 8vo. $4.00. " This work contains a record of certain experiments and researches made under the authority of the Engineer Bureau of the War Department from 1858 to 1861, upon the various hydraulic cements of the United States, and the materials for their manufacture. The experiments were carefully made, and are well reported and compiled."-Journzal.Fiankliet Institute. The Volunteer Quartermaster. Containing a Collection and Codification of the Laws, Regulations, Rules, and Practices governing the Quartermaster's Department of the United States Army, and in force March 4, 1865. By Captain ROELIFF BRINKERHOFF, Assistant Quarter. master U. S. Volunteers, and Post Quartermaster at Washington. 1 vol. 12mo, cloth'. *2.50. This work embraces all the laws of Congress, and all the orders and circulars of the War Office and its bureaus, bearing upon the subject. It also embodies the decisions of the Second Comptroller of the Treasury, so far as they affect the Quartermaster's Departrnent. These decisions have the force of law in the adjustment of accounts, and are therefore invaluable to all disbursing officers. D. Van Nostrand's Publications. Cullum's Military Bridges. Systems of' Military Bridges in Use by the United States Army; those adopted by the Great European Powers; and such as are employed in British India. With Directions for the Preservation, Destruction, and Re-establishment of Bridges. By Brig.-Gen. GEORGE W. CULLUM, Lieut.-Col. Corps of Engineers, U. S. A. 1 vol. 8vo. With numerous Illustrations. cloth. $3.50. "We have no man more competent to prepare such a work than Brig.-Gen. Cullum, who had the almost exclusive supervision, devising building, and preparing for service of the various bridge-trains sent to our armies in Mexico during our war with that country. The treatise before us is very complete, and has evidently been prepared with scrupulous care. The descriptions of the various systems of military bridges adopted by nearly all civilized nations are very interesting even to the non-professional reader, and to those specially interested in such subjects must be very instructive, for they are evidently the work of a master of the art of military bridge-building."- Iashington Chronicle. Haupt's MI[litary Bridges. For the Passage of Infantry, Artillery, and Baggage-Trains; with Suggestions of many new Expedients and Constructions for Crossing Streams and Chasms; designed to utilize the Resources ordinarily at command, and reduce the amount and cost of Army Transportation. Including also Designs for Trestle and Truss Bridges for Military Railroads, adapted especially to the wants of the Service of the United States. By HERMAN HAUPT, Brig.-Gen. in charge of the Construction and Operation of the U. S. Military Railways, Author of " General Theory of Bridge Construction," &c. Illustrated by sixtynine Lithographic Engravings. 8vo, cloth.,t6.50. "This elaborate and carefully prepared, though thoroughly practical and simple work, is peculiarly adapted to the military service of the United States. Mr. Haupt has added very much to the ordinary facilities for crossing streams and chasms, by the instructions afforded in this work."-Boston Cou/ er,. Holley's Railway Practiee. American and European Railway Practice, in the Economical Generation of Steam, including the Materials and Construction of Coal-burning Boilers, Combustion, the Variable Blast, Vaporization, Circulation, Superheating, Supplying and Heating Feed-water, &c., and the Adaptation of Wood and Coke-burning Engines to Coal-burning; and in permanent Way, including Road-bed, Sleepers, Rails, Joint Fastenings, Street Railways, &c., &c. By Alexander L. Holley, B. P. With 77 lithographed plates. 1 vol. folio, cloth. $12.00. * * *'"All these subjects are treated by the author in both an intelligent and intelligible manner. The facts and ideas are well arranged, and presented in a clear and simple style, accompanied by beautiful engravings, and we presume the work will be regarded as indispensable by all who are interested in a knowledge of the construction of railroads, and rolling stock, or the working of locomotives." —Sienti/ic American...~9 D). Van Nostrand's Publications. Authorized U. S. Infantry Tactics. For the Instruction, Exercise, and Manceuvres of the Soldier, a Company, Line of Skirmish ers, Battalion. Brigade, or Corps d'Armee. By Brig.-Gen. SILAS CASR:, U S. A. 3 vols 24mo. Cloth, lithographed plates. $2.50. Vol. I.-School of the Soldier; School of the Company; Instruction for Skirmishers. Vol. II.-School of the Battalion. Vol. III.-Evolutions of a Brigade; Evolutions of a Corps d'Armee. "WAR DEPARTMENT, WASHINGTON, August 11, 1862. "The System of Infantry Tactics prepared by Brig.-Gen. Silas Casey, U. S. A., having been approved by the President, is adopted for the instruction of the Infantry of the Armies of the United States, whether Regular, Volunteer, or Militia "EDWIN M. STANTON, Secretary of War.' U. S. Tactics for Colored Troops. U. S. Infantry Tactics, for the Instruction, Exercise, and Manceuvres of the Soldier, a Company, Line of Skirmishers, and Battalion, for the use of the Colored Troops of the United States Infantry. Prepared under the direction of the War Department. I vol., plates. $1.50. "WAR DEPARTMENT, WASILINGTON, JlCtrch 9, 1S63. "This system of United States Infantry Tactics, prepared under the direction of the War Department, for the use of the Colored Troops of the United States Infantry, having been approved by the President, is adopted for the instruction of such troops. "EDWIN M. STANTON, Secretary of uWar." Kelton's Bayonet Exercise. A New Manual of the Bayonet, for the Army and Militia of the United States. By Colonel J. C. KELTON, U. S. A. With forty beautifully engraved plates. Red cloth. $2.00. "This Manual was prepared for the use of the Corps of Cadets, and has been introduced at the Military Academy with satisfactory results. It is simply the theory of the attack and defence of the sword applied to the bayonet, on the authority of men skilled in the use of arms."-hNew York Times. Berriman's Sword-Play. The Militiaman's Manual and SwordPlay without a Master.-Rapier and Broad-Sword Exercises copiously Explained and Illustrated; Small-Arm Light Infantry Drill of the United States Army; Infantry Manual of Percussion Muskets; Company Drill of the United States Cavalry. By Major M. W. BERRIMAN, engaged for the last thirty years in the practical instruction of Military Students. Fourth edition. 1 vol. 12mo, red cloth. $1.00. "This work will be found very valuable to all persons seeking military instruction; but it recommends itself most especially to officers, and those who have to ase the sword or sabre. We believe it is the only work on the use of the sword published in nis country."-New York Tablet. 10 D. Van Nostrand's Publications. Heavy Artillery Tactics. —1863. Instruction for Heavy Artillery; prepared by a Board of Officers, for the use of the Army of the United States. With service of a gun mounted on an iron carriage. In one volume, 12mo, with numerous illustrations. cloth. $2.50. "WV AR DEPARTMENT, "WASHIN;TON, D. C., Oct. 20. 1862. "This system of Heavy Artillery Tactics, prepared under direction of the War Department, having been approved by the President, is adopted for the instruction of troops when acting as heavy artillery. EDWIN M. STANTON, Secretary of War." "The First Part consists of sixteen lessons relating to the service of the single piece, incldling the gun, howsitzer, mortar, and coluInl)iad; also, the formnnation of batteries, the art f ailring pieces and firing hot-shot. Part Second relates entirely to mechanical mancenvres, and appliances for handling. mounting, dismounting, and transporting heavy pieces. Part Third is of a miscellaneous chnaracter, containing directions ffor embarking and disembarking artillery and ordnance stores; also, tables of dimensions and weights of guns, carriages, shot, shell, machines, and implements, with, charges for, and ranges of heavy artillery. These instructions are not only copious in detail, but aptly illustrated with thirty-nine elegant steel-plate engravings."-Bulletin. Roberts's Hand-Book of Artillery. For the Service of the United States Army and Militia. New revised and greatly enlarged edition. By Major JOSEPH ROBERTS, U. S. A. 1 vol. 18mo, cloth. $1.25. "A complete catechism of gun practice, covering the whole ground of this branch of military science, and adapted to militia and volunteer drill, as wvell as to the regullar army. It has the merit of precise detail, even to the technical ilaulies of all parts of a gun, and how the smallest operations connected with its use can be best performed. It has evidently been prepared with great care, and with strict scientific accuracy."..Vew York Ceteatury. Duane's Manual for Engineer Troops. Consisting of Part I., Pontoon Drill; II., Practical Operations of a Siege; III, School of the Sap; IV., Military Mining; V., Construction of Batteries. By Major J. C. DUANE, Corps of Engineers, U. S. Army. 1'vol. 12mo, cloth. $2.50. "I have carefully examined Capt. J. C. Duane's'Manual for Engineer Troops,' and do not hesitate to pronounce it the very best wiork on the subject of which it treats. "II. W. IIALLECK, l3fajor-Geageroal, U. S. A." Dufour's Principles of Strategy and Grand Tactics. Translated from the French of General G. t. Dufour. By rWILLIAM P. CRAIGHILL, Capt. of Engineers, U. S. Army, and Assistant Professor of Engineering, U. S. Military Academy, West Point. From the last French Edition. Illustrated. In one volume 12mo. cloth. $3.00. "In all military matters General Dufour is recognized as one of the first authorities in Europe, and consequently the translation of this very valuable work is a most acceptable iaddition to our military libraries."-Loondo Noavall and Mlilitary Gazette. D. Van Nostrand's Publications. Instructions for Field Artillery. Prepared by a Board of Artillery Officers. 1 vol. 12mo, illustrated by 122 pages of Engravings. Cloth. $3.00. "WARP DEPARTaMENT, WASHINGTON, Mllarch 1, 1863. "This system of Instruction for Field Artillery, prepare(l under direction of the War Department, having been approved by the President, is adopted for the instruction qf troops when acting as field artillery. "Accordingly, instruction in the same will be given after the method pointed out therein; and all additions to or departures from the exercise and llanceuvres laid down in the system, are positively forbidden. "EDWIN M. STANTON, Secretary of War." Anderson's Evolutions of Field Batteries of Artillery. Translated from the French, and arranged for the Army and Militia of the United States. By Gen. ROBERT ANDERSON, U. S. A. Published by order of the War Department. I vol., cloth, 32 plates. $1. " WAR DEPARTMENT, Nov. 2d, 1S59. "The system of'Evolutions of Field Batteries,' translated firom the French, and arranged for the service of the United States, by Major Robert Anderson, of the 1st Regiment of Artillery, having been approved by the President, is published for the information and government of the army. "All Evolutions of Field Batteries not embraced in this system are prohibited, and those herein prescribed will be strictly observed. J. B. FLOYD, "Secretary of War." Mendell's Treatise on Military Surveying. Theoretical and Practical, including a Description of Surveying Instruments. By G. H. MENDELL, Captain of Engineers. 1 vol. 8vo, with numerous illustrations. cloth. $2.50. " The author is a Captain of Engineers, and has for his chief authorities Salneuve, Lalobre, and Sirnms. He has presented the subject in a simple form, and has liberally illustrated it with diagrams, that it may be readily comprehended by every one who is liable to be called upon to furnish a military sketch of a portion of country." —New York Evening Post. Viele's Haud-book. Hand-Book for Active Service, containing Practical Instructions in Campaign Duties. For the use of Volunteers. By Brigadier-General Egbert L. Viele, U. S. A. 12mo, cloth. $1. "It is a thorough treatise, copiously illustrated, and embraces a complete drill by conlpany, regiment, &c. It also embraces instructions in regard to the camp, fortifications, rations, an(l mode of cooking them, and has a manual for light and heavy artillery."Ne~ Rlavent Palladium. A Treatise on the Camp and March. With which is connected the Construction of Field-Works and Military Bridges; with an Appendix of Artillery Ranges, &c. For the use of Volunteers and Militia in the United States. By Captain Henry D. Grafton, U. S. A. 1 vol 12mo, cloth. 75 cents. 12 c-..-. D. Van N2ostrand's Publications. The Automaton. Regiment; or, Inlfantry Soldier's Practical Instructor.-For all Regimental Movements in the Field. By G. Douglas Brewerton, U. S. Army. Neatly put up in boxes, price $1; when sent by mail, $1.40. The "Automaton Regiment" is a simple combination of blocks and counters, so arranged and designated, by a carefully considered contrast of colors, that it supplies the student with a perfect miniature regiment, in which the position in the battalion of each company, and of every officer and man in each division, conmpany, platoon, and section, is clearly indicated. It supplies the studious soldier with the means whereby he can consult his "tactics," and. at the same time join practice to theory by manceuvring a mimic regiment. I hereby certify that I have examined the "Automaton Regiment," invented by G. Douglas Brewerton, late of the United States Regular Army, and now serving as a Volunteer Aide upon my military staff, and believe that his invention will prove a useful and valuable assistant to every student of military tactics. I take pleasure in recommending it accordingly. B. SAXTON, Brigadier-General Volunteers. The Automaton Company; or, Infantry Soldier's Practical Instructor.-For all Company Movements in the Field. By G. Douglas Brewerton, U. S. A. Price in boxes, $1.25; when sent by mail, $1.95. The Automaton Battery; or, Artillerist's Practical nl structor.-For all Mounted Artillery Manceuvres in the Field. By G. Douglas Browerton, U. S. A. Price in boxes, $1; when sent by mail, $1.40. These productions are of a similar character, and cannot fail to be of great value to the military student. They are object lessons, that will teach more in an hour than mere verbal instruction could in a month. They cannot be too highly comlmended to both officers and men.-GCommercial Advertiser.. Monroe's Company and Skirmish Drill.-The Company Drill of the Infantry of the Line, together with the Skirmish Drill of the Company and Battalion, after the method of General Le Louterel. Bayonet Fencing; with a Supplement on the Handling and Service of Light Infantry. By J. Monroe, Colonel 22d Regiment, N. G., N. Y. S. M., formerly Captain U. S. Infantry. 1 vol., 32mo, cloth. 75 cents. This is a most valuable and timely little man tal. It should be in the hands of every new recruit.-Chicago Tribule. School of the Guides. —Designed for the use of the Militia of the United States. By Colonel Eugene Le Gal, 55th Regiment, N. Y. S. Af. cloth, 60 cents. "This excellent compilation condenses into a compass of less than sixty pages all the instruction necessary for the guides, and the information being disconnected with other matters, is more readily referred to and more easily acquired."-Louisville Journcal. L 13 D. Van Nostrand's Publicatlions. Craighill's Armlny Oflcer's Pocket Companion. Principally designed for Staff Officers in the Field. Partly translated from the French of M. DE ROUVRE, Lieutenant-Colonel of the French Staff Corps, with Additions from standard American, French, and English Authorities. By WM. P. CRAIGHIIL, First Lieutenant U. S. Corps of Engineers, Assist. Prof. of Engineering at the U. S. Military Academy, West Point. 1.vol. 18mo, full roan. $2.00.l " I have carefully examined Capt. Craighill's Pocket Companion. I find it one of the very best works of the kind I have ever seen. Any Army or Volunteer officer who will make himself acquainted with the contents of this little book, will seldom \be ignorant of his duties in camp or field. II. W. HALLECK, Ifcajor- General l. S. A." H1unter's Manual for Quartermasters and Commissaries. Containing Instructions in the Preparation of Vouchers, Abstracts, Returns, etc., embracing all the recent changes in the Army Regulations, together with instructions respecting Taxation of Salaries, etc. By Captain R. F. HUNTER, late of the U. S. Army. 12mo, cloth, $1.25. Flexible morocco, $1.50. "This is the only work of the kind extant. It is based on the latest regulations of the War Department, and will be regarded as authority by those officers for whose use it is designed."-SaturdULy Evening Gazette. Ordronaux's Manual of Instructions for Military Surgeons, in the Examination of Recruits and Discharge of Soldiers. With an Appendix, containing the Official Regulations of the Provost-Marshal General's Bureau, and those for the formation of the Invalid Corps, etc., etc. Prepared at the request of the United States Sanitary Commission. By JoIN ORDRONAUX, M. D., Professor of Medical Jurisprudence in Columbia College, New York. 12mo. Half morocco. $1.50. " In a condensed fornt, it is an admirable treatise on the important subjects of which it treats. The author has aimned to be brief without being obscure, to omit nothing of real importance, and to draw his mnaterials from the best sources. He treats of the physical disabilities which have relation to the military service, and of these alone. Medical Examiners are instructed in their dluties, and the method of discovering feigned, artificially produced, anl concealed diseases is pointed out. The book will Wxove valuable to all who are concerned in the manipulation of recruits or conscripts. An Appendix contains official regulations and instructions relative to the Provost-Marshal's office, the Invalid Corps, etc."-Conzumercial Advesltiser. Ordronaux's firnts on the Preservation of Health in Armlies. For the use of Volunteer Officers and Soldiers. By JOHN ORDRONAUX, M. D. New edition, 18mo, cloth. 75 cents. 14 D. Van Nlostrand's Publicctlions. Thomas's Rifled Ordnance. A Practical Treatise on the Application of the Principle of the Rifle to Guns and Mortars of every Calibre. To which is added, a new theory of the initial action and force -of Fired Gunpowder. By LYNALL THOMAS, F. R. S. L. Fifth edition, revised. One volume. octavo, illustrated. cloth- $2.00. "At a time when the manufacture of guns engrosses the attention of thousands on thousands, any practical treatise which may suggest desirable alterations or innovations is of importance, and deserves that attention we doubt not will be extended to the present volutne."-Boston Evening Gazette. Wilcox's Rifles and Rifle Practice. An Elementary Treatise on the Theory of Rifle Firing; explaining the causes of InaccurEcy of Fire and the manner of correcting it; with descriptions of the Infantry Rifles of Europe and the United States, their Balls and Cartridges. By Captain C. M. WILCOX, U. S. A. New edition, with engravings and cuts. Green cloth. $2.00. "The book will be found intensely interesting to all who are watching the changes in the art of war arising fromrthe introduction of the new rifled arms. We recommend to our readers to buy the book."-lJfilitary Gazette. Lendy's Maxims and Instructions on the Art of War. Maxims, Advice, and Instructions on the Art of War; or, A Practical Military Guide for the use of Soldiers of all Arms and of all Countries. Translated from the French by Captain LENDY, Director of the Practical Military College, late of the French Staff, etc., etc. 1 vol. 18mo, cloth. 15 cents. " This book treats generally of the art of war and the conduct of campaigns, and without going into all the details of a soldier's business, aims to explain the principles on which an army may be well established in canip, or successfully led and manceuvred on the field."-Providence Journatl. Andrews's Hints to Company Officers oni their Military Duties. By Captain C. C. ANDREWS, Third Regiment Minnesota Volunteers. 1 vol. 18mo, cloth. 60 cents. "This is a hand-book of good practical advice, which officers of all ranks may study with advantage."-Philadelphicc Press. lIeth's System of Target Practice.-For the use of Troops when armed with the Musket, Rifle-Musket, Rifle, or Carbine. Prepared principally from the French, by Captain Henry Heth. 10th Infantryv, U S. A. 18mo, cloth. 75 cents. 15 D. Van N2ostrand's Publications. Miinifie's Meehanical Drawing. A Text-Book of Geometrical Drawing, for the Use of Mechanics and Schools, in which the Definitions and Rules of Geometry are familiarly explained; the Practical Problems are arranged from the most simple to the more complex, and in their description technicalities are avoided as much as possible. With Illustrations for Drawing Plans, Sections, and Elevations of Buildings and Machinery; an introduction to Isometrical Drawing, and an Essay on Linear Perspective and Shadows. Illustrated with over 200 Diagrams engraved on Steel. By WILLIAM MINIFIE, Architect. Seventh edition. With an Appendix on the Theory and Application of Colors. 1 vol. 8vo, cloth. $4.00. " It is the best work on Drawing that we have ever seen, and is especially a text-book of Geometrical Drawing for the use of Mechanics and Schools. No young Mechanic, such as a Machinist, Engineer, Cabinet-Maker, Millwright, or Carpenter,. should be without it.' —,ientific Avierican. "One of the most comprehensive works of the kind ever published, and cannot but possess great value to builders. The style is at once elegant and substantial."-Pennsylvania Iqnirer. "We think this the best work on this subject, which is saying very much; as much attention has been given to the science of Drawing. There is nothing in the range of drawing that cannot be found in this book, and which is not well explained."-Ohio Teacher. "Whatever is said is rendered perfectly intelligible by remarkably well executed diagrams on steel, leaving nothing for mere vague supposition; and the addition of an introduction to isometrical drawing, linear perspective, and the projection of shadows, winding up with a useful index to technical terms."l-Glcsgow lfechanic's Journal. Mlinilie's Geometrical Drawing. Abridged from the Octavo,edlition, for the use of Schools. Illustrated with 48 Steel Plates. Fifth edition. 1 vol. 12mo, half roan. $1.50. Peirce's System of Analytic Mechanics. Physical and Celestial Mechanics, by BENJAMIN PEIRCE, Perkins Professor of Astronomy and Mathematics in Harvard University, and Consulting Astronomer of the American Ephemeris and Nautical Almanac. Developed in four systems of Analytic Mechanics, Celestial Mechanics, Potential Physics, and Analytic Morphology. 1 vol. 4to, cloth. $10.00. Dietionary of Weights and Measures. Universal Dictionary of Weights and Measures, Ancient and Modern, reduced to tie standards of the United States of America. By J. H. ALEXANDER. New edition, enlarged. 1 vol. 8vo, cloth. $2.50 16