Cornell University Library 
 TD 910.C13 1880 
 
 Sanitary engineering. 
 
 3 1924 004 131 391 
 
Cornell University 
 Library 
 
 The original of tiiis book is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31 9240041 31 391 
 
North Carolina Board ofiiEAtf^ 
 
 Sanitary Engineering. 
 
 SECOND EDITION. 
 
 By WILLIAM OAIN, O. B. 
 Member of the North Carolina Board of Health. 
 
 KALEIGH : 
 P. M. HALE, AND EDWAKDS, BEOUGHTON & 00., 
 
 State Printers and Binders, 
 ISSO. 
 
/cornell\ 
 university 
 
 UBRARY^ 
 
SANITARY ENGINEERING. 
 
 SECOND EDITION. 
 
 By ■VV'ir.LI^M: CA.IN, C. E. 
 
 CHAPTER I. 
 
 GENEEAL CONSIDERATIONS. 
 
 Death rates lowered by sanitary works.— We are 
 
 told upon the best authority that in England there occurs 
 annually upwards of four million cases of preventable sick- 
 ness; and that 125,000 persons are premature cut off every 
 year from a neglect of sanitary precautions. 
 
 Now if this be true in a country which has adopted the 
 best known sanitary precautions, at great expense, how much 
 more significant will the records in this State appear, 
 where the only outlay that may be classed under the head 
 " sanitary," is generally made in meeting doctors' bills and 
 fwneral expenses. 
 
 It is further stated thait in England, since the sanitary 
 precautions have been instituted, that the death rate has 
 been lowered by from one-fourth to one-third, and is besides 
 decreasing from year to year. The following table, refer- 
 ring to a jew localities in England, taken from Latham's 
 " Sanitary Engineering," speaks more forcibly than all the 
 other arguments that may be presented, especially to those 
 who have paid but little attention io sanitary subjects, and 
 are inclined to be skeptical as to the great actual saving of 
 life that may be attained. I presume the table is made out 
 
SAKITARY ENGINEERING. 
 
 for 1873, the date of the publication, and that the " works " 
 are of the " water sewerage " kind : 
 
 Name of Place. 
 
 Banbury,.... , 
 
 Cardiff, 
 
 Corydon, , 
 
 Dover , 
 
 Ely 
 
 Leicester, 
 
 Macclesfield, 
 
 Merthyr, , 
 
 Newport, 
 
 Kugby, 
 
 Salisbury, .... 
 ■Warwick, ..., 
 
 Population 
 
 in 
 
 1861. 
 
 10.338 
 
 32,954 
 
 30,229 
 
 23.108 
 
 7,847 
 
 68,056 
 
 27,475 
 
 52,778 
 
 24,756 
 
 7,818 
 
 9.030 
 
 10,570 
 
 ^ 
 
 o n 
 oS.2 - 
 
 a> t- S o 
 tJB j; o fe 
 
 "^25 
 
 23.4 
 33.2 
 23 7 
 22.6 
 23.9 
 26.4 
 29.8 
 33.2 
 31.8 
 19.1 
 27.0 
 23.7 
 
 is- 
 
 SCO 
 
 a ft 
 
 s ° 
 
 -^^.a 
 
 a o 
 
 a 
 
 20.5 
 23.6 
 1S.6 
 20.9 
 20.5 
 35.3 
 23.7 
 26.2 
 21.6 
 18.6 
 219 
 21 
 
 
 12J 
 
 .32 
 
 22 
 
 7 
 
 14 
 
 20 
 18 
 32 
 
 ^ 
 
 20 
 
 n 
 
 a > <o 
 
 aSft 
 'O o 
 ass s 
 
 48 
 40 
 63 
 3S 
 56 
 48 
 48 
 60 
 36 
 10 
 75 
 52 
 
 OS's 
 
 t! O » 
 
 41 
 17 
 17 
 20 
 47 
 32 
 31 
 11 
 32 
 43 
 49 
 19 
 
 A previous statement would indicate that the death rate 
 is still being steadily lowered. As Latham states, the most 
 healthy districts show but a small saving compared with 
 the others ; though nearly all show a marked diminution 
 in certain diseases — typhoid fever and phthisis. 
 
 Similar results have attended the enforcement of sanitary 
 measures in some of our American cities. 
 
 A striking illustration is St. Louis, where, it is stated, 
 that from 1867 (when the Board of Health was organized,) to 
 1877, although the population had more than doubled, the 
 death rate had decreased, so that actually in 1877 there were 
 fewer deaths than in 1867. 
 
 The average mortality for this country is about 20, rang- 
 ing from 17 to 30 in 1,000 generally ; but St. Louis shows a 
 death rate of only 11, which apart from its site, " must be 
 ascribed largely to its excellent water supply and sewer 
 system." 
 
 Economical Aspects. — Apart from the humanitarian 
 view of this question, it may be considered in its economi- 
 
GENERAL CONSIDERATIONS. 5 
 
 cal aspects : thus Latham has taken Croyden, where the 
 total cost of sewers, &c., was $943,800, and estimated the 
 saving in funerals, in sickness (allowing that for every life 
 saved 25 would escape sickness, the saving being estimated 
 at $5 for every sick person,) and in the labor, for 6J years 
 only, by the prevention of premature death, at a total of 
 over $1,000,000, which thus exceeds, in the short space of 6J 
 years, the total cost of the sanitary works. 
 
 Yellow Fever caused by Filth. — How much more 
 striking would be the result, were we to take some of our 
 own plague stricken cities in America ! Where has the yellow 
 feoer Us origin.^ In the filthiest port in the world, Havana, 
 where "the tide being almost imperceptible, all the empty- 
 ings of the sewers remain in the harbor until they become 
 a foetid and revolting mass of corruption." From there 
 the seeds of the yellow fever are carried by ships to other 
 ports ; and when these are foul, the scourge begins. 
 
 Gen. Butler at least has the merit of having to a great 
 extent kept New Orleans dean and free from the epidemic 
 during his occupancy of the city. In 1878, however, in 
 consequence of the foulness of the city, she suffered the 
 most terrible visitation ; whilst in 1879, through the ener- 
 getic workings of some of her most public spirited citizens, 
 in carrying out sanitary measures, the mortality from yellow 
 fever was very much reduced. 
 
 Galveston was kept clean and escaped the plague. Hunts- 
 ville, Ala., actually sheltered yellow fever victims with im- 
 punity; whilst Memphis in 1879 again suffered from her 
 foulness. 
 
 What more instructive lesson than the facts just given? 
 
 Advantages of Keeping Clean. — If we keep clean 
 there is less chance of dying, greater enjoyment of life from 
 increased health, fewer bereavements and a positive pecu- 
 niary gain to the community, even including the cost of 
 sanitary works. Health, population, and money values 
 also, generally go hand in hand, when other conditions are 
 avorble. 
 
6 SANITARY ENGINEERING. 
 
 On the contrary, if we disobey the Divine Will, by run- 
 ning counter to natural laws, we are punished for the sin 
 of disobedience. Here we have rewards and punishments — 
 both teaching their own moral lessons. Choose between 
 them. 
 
 Is North Carolina Clean?— Let us now inquire as to 
 our own cleanliness, which, the good book tells us, is next 
 to Godliness. The result of this inquiry would be, that 
 typhoid fevers, diphtheria and certain enteric fevers that 
 are now classed as "filth diseases," are common, especially in 
 the larger towns of the State ; and that these diseases are 
 suf&ciently accounted for by bad wells, foul yards, primes, and 
 eess-pools ; the latter tainting the air with their gases and 
 the water with their dissolved impurities. 
 
 There are but few privies in the State that ought not to 
 be abolished, and some good system substituted in their 
 place. It is one object of this paper to suggest such systems. 
 
 But it is not sufficient that our own house alone be free 
 from reproach. The individual may suffer ■when it is only 
 his neighbors who are to blame. The whole community, 
 as a unit, must practice cleanliness. 
 
 The germ of disease, engendered amid the surroundings 
 of filth, if wafted to the palace, can strike as deadly a blow 
 there as in the dirty hovel, as recent examples show. 
 
 Filth and Disease go hand in hand. — Of the exact na- 
 ture of the poison generated by filth we know little ; but it 
 has certainlj' been demonstrated in numerous cases that the 
 ravages of epidemics are in direct proportion to the foulness 
 of the locality. Thus in one city, diphtheria followed the 
 line of bad sewers, in another of bad wells. Bad water 
 is one of the most efficient agents in spreading disease. 
 
 The cholera of 1853, in London, attacked districts fur- 
 nished with unfiltered Thames water with 3J times the 
 severity experienced by neighboring districts supplied with 
 Thames water filtered through sand and charcoal. 
 
GENERAL CONSIDERATIONS. 7 
 
 It has become, as it were an accepted truth in sanitary 
 science that the fatal effects of epidemics may either be pre- 
 vented, or their spread materially hindered by a proper at- 
 tention to sanitary precautions. These precautions simply 
 consist in the having, at all times, pure air, wholesome food, 
 and good water. It is only the first and last of these requi- 
 sites that will be considered in what follows, as they per- 
 tain more especially to the science of "Sanitary Engineer- 
 ing ;" though it is to be observed that wholesome food is to 
 to a certain extent dependent upon the good water or milk 
 used in the cooking. 
 
 By a disregard of these prerequisites to health — and they 
 are more or less disregarded by us all — we enfeeble the sys- 
 tem, suffer a loss of vital energy, and are thus fit subjects 
 for an attack by the first epidemic. 
 
 The " debilitating effects" of large cities are mainly due 
 to the poisonous gases, generated by the putrid matter of 
 sinks, sewers, &c., which gases find their way into chambers 
 through faulty pipes and traps, or are otherwise diffused 
 through the atmosphere. When the debilitated person 
 seeks the pure water and bracing air of the mountains, the 
 relief is almost instantaneous, thus proving the life-giving 
 qualities of pure air and pure water. 
 
 The Science of Prevention. — The Science of Medicine, 
 so long confined to the art of healing alone, now declares in 
 favor of the Science of Prevention as the higher philosophy. 
 
 Let us, then, state the principles of this latter science 
 clearly and succinctly ; not entering into many details, but 
 giving mainly those principles and facts that should be 
 known by every one. Any system proposed must be a sim- 
 ple one — the simplest is generally the best — to meet the 
 needs and comprehension of all classes. 
 
 The law organizing the N. C. Boa,rd of Health requires a 
 monthly report from each county on vital statistics. It is 
 of great importance that this law be faithfully carried out, 
 
8 SANITARY ENGINEERING. 
 
 SO that the effect of the suggestions given below, where car- 
 ried out, may be ascertained. 
 
 The same act requires that the Board " shall gather in- 
 formation, for distribution among the people, with the 
 especial purpose of informing them about preventable dis- 
 eases." 
 
 Disease may be prevented, other conditions being favor- 
 able, by a proper attention to drainage, ventilation, water sup- 
 ply, and the prompt disposition of sewage matters. 
 
 We shall consider the subject in the above order. 
 
DRAINAGE. 9 
 
 CHAPTER II. 
 
 DRAINAGE. 
 
 Wet and Dry Soils. — The farmer well knows that 
 when a wet soil is not drained, valuable plants refuse to 
 grow, due to the land being " cold" and " sour ;" and that 
 by drainage such lands are often converted into the best 
 quality of lands, owing to the replacement of the excess 6f 
 water and vegetable acids by warm, dry air, so that the 
 roots now find the proper amount of air, moisture and tem- 
 perature to satisfy the conditions of growth. 
 
 The sun's rays now cause a healthy decomposition of or- 
 ganic substances, in place of the imperfect one that seems 
 the necessary concomitant of moisture in excess ; so that 
 now neither acids are formed in the ground, nor dangerous 
 organic impurities thrown oflf into the air. 
 
 It is the latter that produce, indirectly or otherwise, the 
 intermUtent and remUtent fevers, so common over the whole 
 South. The best cure is drainage. 
 
 " The fens of Lincolnshire, in England, and marshy dis- 
 tricts along the lower Thames were formerly greatly 
 scourged with fever and ague and with malarial neuralgia. 
 The extensive drainage operations carried on in these dis- 
 tricts have had the effect of removing these ailments en- 
 tirely." 
 
 Where ground is water-logged, it is unfit for human hab- 
 itation. 
 
 Drainage is especially necessary where sewers are laid, as 
 the sewer gases readily penetrate the brick walls of the 
 sewers, and then find access to cellars, etc. A dry soil will 
 condense enough oxygen to burn these gases up, as will be 
 more fully explained further on. 
 
 Malarial Poison. — It is generally believed that all 
 damp places, as most ponds, marshes, swamps, river bottoms 
 subject to overflow, etc., portions of which, along the banks, are 
 
10 SANITARY ENGINEERING. 
 
 alternately wet and dry, are such as originate malarial poison , 
 and must continue to originate it so long as such conditions 
 hold. The occasional overflow of salt water aggravates the 
 evil, as also the accumulation of leaves, decaying wood, etc., 
 especially where thick vegetation causes a stagnaition of the 
 air, with dense shade. It is obviously correct then to cut 
 down such vegetation immediately around the damp lo- 
 cality, drain it and put it under cultivation. "If the rise and 
 fall of the wafer, in the pond or marsh, alternately covers 
 and exposes much of the banks — i. e., if the banks are not 
 vertical, or made so — then the body of water must be en- 
 tirely drained off, if possible ; otherwise the injurious de- 
 compositions due to wet soils will continue to go on and 
 breed malaria. It is found that winds can transport malaria 
 some miles. It is therefore best not to cut down open forests 
 at a little distance from the, damp localities, as they inter- 
 cept the malaria to a considerable extent. 
 
 It is very often the case that dwelling houses, in city and 
 country both, are surrounded with such a dense mass of 
 shrubbery (perhaps intended to satisfy the aesthetic taste) 
 as to cut off both fresh air and sunshine; thus rendering 
 the house and yard damp and the air impure. Such vaults 
 should be rendered habitable by the free use of the axe. It 
 is not well to have too much shade in our cities ; pure air 
 and sunshine are the best purifying agents we have. It is 
 a custom (but rarely " honored in the breach") to deny earn- 
 estly and with many asseverations that malaria affects the 
 locality one lives in. Sad must be the condition of that 
 person, who, even if he admits an occasional malarial fever, 
 cannot point out another locality where the malady is in- 
 finitely more distressing. 
 
 Acting upon this recognized principle, it is suggested that 
 
 whilst the mountains and hilly regions hardly ever originate 
 
 . fever and ague, that much of the remainder of the State is 
 
 subject to it to a greater or less extent, and therefore that 
 
 thorough drainage is one of the first requisites to increased 
 
DRAINAGE. 11 
 
 healthfulness. Whilst thinly settled districts may not be 
 able to institute proper precautions, yet the larger towns 
 can drain the ponds, low places, roads and mother earth 
 generally in their vicinity. 
 
 In the last column of the 'previous table is seen the re- 
 duction in the death-rate from phthisis of twelve English 
 towns. " This saving of life is ascribed to the effect of 
 drainage works in drying the subsoil of those places." 
 
 In this State, Salisbury may be given as an instance 
 where the drainage of a large pond near the town has very 
 largely diminished the prevalence of malarial fevers. 
 
 Subsoil Drainage. — In the subsoil drainage of streets 
 and roads, covered drains, formed of rock or tile, should be 
 used in preference to open drains. Open drains, unless the 
 soil is very tenacious, and can stand at a steep slope, take 
 up too much space. Besides they are constantly needing 
 repairs and often hold stagnant water and decayed filth ; so 
 that in some countries their courses have been marked by 
 excessive ravages of cholera over adjoining districts. 
 
 A given tract of land is best drained for agricultural pur^ 
 poses by stone or pipe drains of 1 to 2 inches diameter, run- 
 ning straight down the hillsides (when not too steep), in 
 parallel rows, 25 to 50 feet apart, and 30 to 36 inches below 
 the surface. These small drains discharge into larger in- 
 tercepting drains, run down "the hollows; and these, in turn, 
 empty into larger drains (that may often be open), that fol- 
 low the courses of the valleys and perhaps serve as the 
 water channels of small streams. Such draining necessarily 
 ensures a deep, mellow soil, that not only satisfies the needs 
 of agriculture, but is in perfect keeping with the require- 
 ments of health. Towns should at least keep the subsoil 
 dry, by covered drains run along the streets and elsewhere, 
 at sufficient depths to drain the cellars thoroughly and to 
 prevent standing pools of water. 
 
 Tile drains 2 inches in diameter, under the side-ditches, 
 or one 3-inch drain under the middle of the road, is suf- 
 
12 SANITARY ENGINEEEINQ. 
 
 ficient generally. An outlet drain should run from the de- 
 pressions in the road. A drain or culvert crossing the road 
 should be large enough to pass 2 inches of rainfall in one 
 hour when the drainage area is small, 1 inch for a valley- 
 two to three miles long, and scr on. 
 
 All streets and roads should be built higher in the mid- 
 dle than at the sides, and should have gutters deep enough 
 to carry off storm waters, unless there are specially con- 
 structed large drains for this purpose (as to which see 
 "Water Sewerage," further on). 
 
 Complete Drainage. — If such drains (designed to carry 
 off all the rain water. Slops and waste water that is not ab- 
 sorbed by the ground,) are contemplated, regard must be 
 paid, in laying them, to the future sewerage of the town, 
 even if this is not carried on at the same time as the drain- 
 age system proper. 
 
 The drainage of large districts, swamp lands, low lands, 
 etc., varies so with the configuration of the ground that it 
 is impossible to give any set of rules that apply in all cases. 
 As a rule, the district is intersected by a number of dykes, 
 often parallel, that drain into larger dykes or streams. 
 
 Intercepting dykes are often dug around the whole area 
 to be drained to prevent the access of water from without. 
 
 As an illustration, the low " Landes " in France may be 
 given. Here 260,000 acres of-the richest lands in France 
 have been reclaimed, chiefly by cutting open canals 16 to 
 20 feet wide, following the natural slope of the plateau with 
 a fall of 1 to 2 per 1,000. Of these canals 1,600 miles have 
 been completed. For 75 miles along the coast, huge sand- 
 banks protect the country from the sea, the drainage along 
 them being received by a large collecting canal 40 feet wide. 
 The works cost $1,700,000, about ; and the value of the re- 
 claimed land is estimated at upwards of $56,000,000. 
 
 " The fevers which formerly ravaged the country have disap- 
 peared, and the country may now be considen-ed one of the most 
 healthy in France" 
 
DEAINAGE. 13 
 
 If the land is beneath the sea level, as in Holland, then 
 the water must be pumped out of the area, the latter being 
 protected from the encroachments of the sea by an embank- 
 ment. 
 
 Straightening the course of rivers, likewise, is efficient in 
 causing increased scour, a lowering of the bed and a lessen- 
 ed liability to overflow. 
 
 Ponds are easily drained by simply cutting a ditch of the 
 proper size through the natural or artificial embankment 
 surrounding them. The greater the extent of the water 
 shed, and the greater the rainfall, and the imperviousness 
 of the surface, the largier of course is the ditch. 
 
 The so called "wet weather" ponds, often on high ground, 
 should never be tolerated, as they present the very condi- 
 tions for fostering malaria — a large area, alternately wet and 
 dry.* 
 
 The natural division of a country for drainage purposes 
 is into districts belonging to the same water shed, bounded, 
 of course, by the ridges and streams. Considerable incon- 
 venience has been caused in some thickly settled countries 
 by a disregard of natural boundaries. 
 
 The extent to which drains exert an influence on the 
 ground, on either side depends on their depth, and the char- 
 acter of the soil, whether very retentive or porous. Their 
 action is analagous to that of wells given further on, except 
 that the bottom of the ditch does not generally reach the 
 level of complete saturation of the ground as is often the 
 case in wells. 
 
 It is best not to open new ditches from " June to Novem- 
 ber" in malarial districts, unless for house drainage. Cel- 
 lars should be drained by leading a pipe from below the 
 bottom of the cellar to some convenient exit to the open air 
 
 *See Kerr's Geology of N. C, (Introduction) for an excellent presenta,- 
 tion of the leading topographical features of the State, egpecially its 
 swamps and pocosins, as relating to the matter in hand. 
 
14 
 
 SANITARY ENGINEERING. 
 
 at a lower level; or similar drains may be laid just outside 
 of the building. 
 
 It is plain that greater attention should be paid to drain- 
 age in towns near our sea coast than in the hilly regions, as 
 decomposition is generally greater, due to increased mois- 
 ture and temperature, not forgetting however that its neg- 
 lect anywhere must cause pernicious effects. 
 
VENTILATION. 15 
 
 CHAPTER III. 
 
 VENTILATION. 
 
 The Constituents of the Air. — It has been found that 
 in certain manufactories and machine shops that the air is 
 so filled with certain impurites that 30 years is the maxi- 
 mum age attained by the operatives. Such instances (and 
 they may be multiplied), though they indicate criminal 
 neglect in the management, are fortunately exceptional, and 
 need not be considered here. 
 
 ' The impurities that we shall consider under this head, 
 as concerning ventilation, result from the breathing of men 
 and animals and the burning of gas, oil, etc., in illumination 
 and heating. 
 
 Country air, wherever analyzed, is found to contain in 
 1 volume nearly 1-5 oxygen to 4-5 nitrogen, with small variable 
 amounts of aqueous vapor, ammonia, carbonic acid and 
 certain microscopic organisms, besides dust, etc. 
 
 If phosphorus is burnt in a bell jar, placed over water, it 
 combines with nearly all of the oxygen in the confined air, 
 forming white fumes of "phosphorus pentoxide," that are 
 soon entirely absorbed by the water, leaving nearly pure 
 nitrogen in the jar. The water rises so as to fill about one- 
 fifth of the original air space in the bell jar, thus showing 
 that the substance (oxygen) abstracted is nearly one-fifth 
 by volume of the whole. The gas (nitrogen) r\ow remain- 
 ing in the jar is colorless, inodorous, and does not support 
 combustion or animal life. Pure oxygen gas, (which is 
 readily obtained separately by heating mercury oxide or 
 potassium chlorate, etc.), is likewise colorless and inodorous, 
 but it supports combustion readily — iron even burning 
 (oxidizing) in it with great brilliancy. 
 
 The oxygen is the life-giving principle of the air. An animal, 
 however, exposed to pure oxygen gas is over- stimulated to 
 such an extent that it soon dies. The nitrogen, therefore , 
 
16 SANITARY ENGINEERING. 
 
 acts as a diluent of the oxygen, and it is found that the 
 above proportion of 4 to 1 cannot be much varied from 
 without deleterious consequences ensuing. The oxygen is 
 not chemically combined with the nitrogen, it is simply 
 mixed with it as sugar is dissolved in water — the little atoms 
 of the one penetrating the spaces between the atoms of the 
 other without destroying the transparency of the medium_ 
 Dr. Angus Smith has made a large number of analyses of 
 air in various parts of Great Britain. The amount of oxy- 
 gen by volume in 10,000 parts of air are given for various 
 localities as follows : 
 
 Mountain air, 2099 parts. 
 
 Towns (average) 2096 " 
 
 Room (rather close) 2089 " 
 
 Pit of a theatre, 11.30 P. M., 2074 " 
 
 Backs of houses and closets, 2070 " 
 
 When air contains only 1850 parts of oxygen to 10,000 of 
 air, it will not support the combustion of a candle, neither 
 will it support life long. The relative densities of oxygen 
 and nitrogen are as 16 to 14, so that an average composition, 
 of air by weight in 10,000 parts is oxygen 2310, nitrogen 
 7690. 
 
 The invisible aqueous vapor exists in the air at all times 
 in various quantities, often condensed as visible clouds, deyr, 
 etc. Its amount varies greatly with the temperature. 
 Thus one cubic foot of air at 90° Fah. can hold 14.50 grains 
 of aqueous vapor as invisible gas ; whilst air at the freezing 
 point, 32° Fah., can hold only 2.37 grains of water gas. 
 The air in both cases is said to be "saturated,?' since it can- 
 not hold any more water gas, as gas ; any excess being pre- 
 cipitated as rain, or formed into the liquid particles consti- 
 tuting fog or cloud and becoming therefore visible. In fact 
 suppose air, saturated at 90°, to be cooled down to 32° sud- 
 denly: then 12.13 grains of rain will fall for every cubic 
 
VENTILATION. 17 
 
 foot of air, leaving only a little over one-seventh of the 
 original moisture in the air! It is upon this principle that 
 the phenomena of raiu, dew, etc., depend. 
 
 It will have been noticed by those who read the daily 
 reports given by the signal stations, that there is a column 
 marked "relative humidity." This gives the per centage of 
 full saturation of the air at the time of observation. Thus,, 
 "relative humidity 60," would indicative that the air con- 
 tains 60 per cent, by weight of the water gas it can hold,, 
 without fog forming. 
 
 From Kerr's Geology of North Carolina, p. 87, we find 
 the average yearly humidities of several places as follows :: 
 Wilmington 57, Charlotte 65, St. Louis 67, London 80 and 
 New Orleans 86; the first two giving only the mean from 
 a little over one years observations. Whilst in London fog 
 is common, on the coast of the Red Sea a cloud never forms,, 
 the dryest air there during a simoom containing only one- 
 fifteenth of the saturating quantity. 
 
 Now it is well known that excessive moisture is deleteri- 
 ous to weak throats, lungs, etc. As to the effect of extreme 
 dryness, I am not informed, save that these-little-red hot- 
 panting-cast iron-stoves produce a bad effect on the air, 
 which is very much ameliorated by evaporating water in 
 vessels placed over them. The bad effect must be due 
 largely to the drying of the air. Thus to take our previous 
 example, if the air near the stove is heated only from 32° to 
 90°, and we suppose it "saturated" at the lower temperature, 
 then at the higher one it has only the same amount of 
 water gas, but it can hold nearly seven times as much ; and 
 if we suppose it only half saturated at 32, then at 90 it will 
 be nearly as dry as the air of a withering simoom, and at 
 highest temperatures much dryer! Such extremes cannot 
 fail to be unwholesome, and therefore if stoves are to be 
 used, let them be large and heated as little as will give the 
 necessary warmth. 
 
18 SANITARY ENGINEERING. 
 
 Another important constituent of the air is ammonia, 
 though it exists in conaparatively minute quantities (about 
 1 in 1,000,000 of air); still it is mainly from this ammonia 
 that vegetables obtain the nitrogen necessary to form their 
 seeds and fruit. It is given off from urine and stable 
 manure, unless gypsum is added to fix it. It is not injuri- 
 ous by itself in small quantities and need not be further 
 considered, f 
 
 The most important, by far, of the inorganic air constitu- 
 ents, next to oxygen, is carbonic acid. Its amount varies 
 within wide limits; thus in Scotland, mountain air con- 
 tained 3.2 at top of mountain, to 3.4 at bottom, in 10,000 
 ■volumes. In London it varies from 3 in open parks to 3.4 
 -on the Thames, and 4 as a rough average, on the streets. 
 In Manchester, the amount of 6.8 to 10,000 was reached 
 during fogs, which is slightly over the extreme allowance 
 considered advisable, which has been fixed by some at 6 in 
 10,000 volumes. Carbonic acid is formed by the chemical 
 combination of carbon with oxygen. Thus when wood, 
 coal, oil or gas is burnt, carbonic acid is formed. It is also 
 given off by the decay of wood, in certain decornpositions, 
 and in the breathing of animals. In fact, if the air in a jar 
 is extracted and then returned from the lungs into the jar 
 again, it will not support the combustion of a candle, 
 although the amount of carbonic acid expired is only 5 per 
 cent. The lungs and body likewise exhale organic impuri- 
 ties, about in proportion to the amount of carbonic acid 
 thrown off, the nose readily detecting the vitiation due to 
 this cause. It is thought by many that these organic im- 
 purities — fatty matters thrown off from the skin, particles 
 of skin, odors, etc., from man and beast — although constitut- 
 ing only the one hundred millionth part of air in the 
 country, or about the five millionth part in crowded cars, is 
 still the most dangerous to man of the air constituents; for 
 it is in every stage of decomposition, and must furnish food 
 ■for the microscopical denizens of the air, some of which no 
 
VENTILATION. 19 
 
 doubt are scavengers, but others are thought by some to 
 cause disease. 
 
 The Atmospheric Germs.— It is well known now that 
 fermentation and certain chemical changes are brought 
 about by minute vegetable or animal growths, whose natural 
 habitat is the air. Tyndall has filtered air through cotton 
 wool to put next the most decomposable substances, and 
 found that no change occurred in them, whilst common 
 air caused decomposition or fermentation to begin. These 
 experiments pretty conclusively disprove the theory of 
 " spontaneous generation." Whether epidemic diseases 
 owe their origin to " atmospheric germs " is not certainly 
 known as yet, but tMt-4ieory is at least plausible, and 
 explains many facts more fully than any other theory 
 generally known. 
 
 We know this much, that sewer gas, even in the minutest 
 quantity, is sometimes fatal, (which is not due to the chemi- 
 cal gases formed, for the chemist breathes them every day), 
 at other times innocuous, especially when free ventilation 
 has been secured. Similarly the discharges, and even gar- 
 ments, of patients suffering with certain fevers can com- 
 municate the disease. Yellow fever, cholera, small pox, 
 etc., is transported in ships by mere clothing. These facts, 
 in connection with the fact that certain organisms in the 
 air seem to follow cholera (as was shown in Germany, and 
 the microscope may reveal the same thing in connection 
 with other epidemics), seem to point to the atmospheric 
 germ as being connected intimately with certain diseases. 
 While the truth is being worked out by scientists, let us 
 make use of known facts and proceed to "scotch the snake'' 
 wherever its presence may be reasonably suspected. 
 
 Vitiation of the Air by Breathing and Illumina- 
 tion. — It is found that a man gives off somewhat over 6-10 
 of a cubic foot of carbonic acid per hour ■ that a lamp or 
 two lighted candles produce the same amount, and that a 
 gas jet, burning 3 cubic feet of gas per hour, produces as 
 
20 SANITARY ENGINEERING. 
 
 much carbonic acid per lw>ur as two or three people. It is 
 true that the gas gives ofif no organic impurities, but if not 
 burning brightly the poisonous carbonic oxide is always 
 formed- 
 
 If we adopt 6 volumes in 10,000 as the safe limit of the 
 amount of carbonic acid to air, then it follows that for 
 every man or lamp or two candles in a room, we must sup- 
 ply at least 1,000 cubic feet of pure air in every hour to 
 dilute the A cubic foot of carbonic acid formed- A gas 
 jet will require two or three times as much pure air. 
 
 But since the admitted air contained carbonic acid, we 
 must supply more air to not exceed the maximum adopted : 
 thus if the admitted air contain three volumes in 10,000 of 
 carbonic acid, we must admit 2,000 cubic feet for every per- 
 son, since the 6-10 of carbonic acid admitted, added to the 
 6-10 expired per hour, gives the ratio of 12 to 20,000 or 6 to 
 10,000 allowed. 
 
 It is said by some, that experience in hospitals shows that 
 from 2,000 to 3,000 cubic feet of fresh air should be admit- 
 ted every hour for each individual } whilst again we are told 
 that for a healthy person in a barrack room 1,200 cubic 
 feet per hour will suffice, and that the vitiation, tested by 
 the sense of smell, for hospitals is not perceptible when 
 somewhat less than the 2,000 to 3,000 cubic feet are pro- 
 vided. 
 
 No fixed standard has thus been agreed upon. In fact, 
 it doubtless varies with the climate and the health of the 
 person. The Laplander can breathe impure air better than 
 we, probably because the organic impurities thrown off by 
 him are not so readily decomposed as in our warmer air. 
 The carbonic acid formed by combustion and respiration 
 being heavier than air at the same temperature, would sink 
 to the floor ; but in consequence of its high temperature, it 
 first rises to the ceiling ; so that as much as 60 to 70 parts 
 of it in 10,000 of air has been found at the top of an ordinary 
 sized room in which two people were sitting and three gas 
 
VENTILATION, 21 
 
 jets burning. At the same temperature, however, we should 
 expect to find the largest amount of it at low elevations, thus 
 vitiating the lower strata of the atmosphere, or room, very 
 greatly. Fortunatelj'^, however, gases have the power of 
 " diffusion," so that a heavy gas will actually rise to mix 
 with a lighter gas; further, it will pass through membranes 
 and thin plates of stucco to effect the same object, so that 
 the amount of carbonic acid is not generally a function of 
 the elevation of a localitj'. 
 
 Where a room has no flue or chimnej^ to keep up a con- 
 stant circulation, then openings should be provided near 
 the top of the room to let the warmer impure gases out, and 
 not let them cool and descend again to vitiate the air we 
 breathe. 
 
 Vitiation by Perspiration. — In addition to the carbonic 
 acid given off by the lungs and skin of a iran, there is ex- 
 haled a considerable degree of moisture, generally loaded 
 too with organic matter, which produces smell. The amount 
 has been estimated at from 1.5 pounds to 2.5 pounds per 
 day on an average. A high temperature, or exercise, causes 
 greater perspiration, thus cooling the person somewhat. 
 
 The amount of moisture given off is considered by some 
 in connection with the carbonic acid exhaled, to ascertain 
 the iheoretical amount of air to admit; but this theoretical 
 amount for most houses is larger than healthy persons seem 
 to require, according to certain experience. This is account- 
 ed for by the fact that opening doors and windows, es- 
 pecially if they are kept open for some time, the draft 
 through cracks, &c., add very much to the volume of ad- 
 mitted air, though not considered in the computation. 
 
 Lime as a Purifier. — If a house has been lately plastered 
 or white-washed, the lime will, at first, take up the carbonic 
 acid with avidity; so will any ordinary mortar; in fact, I 
 have seen artificial stone made by passing the products of 
 combustion of a stove (carbonic acid mainly) by a flue into 
 a room where was placed the mortar, moulded into the re- 
 
22 SANITARY ENGINEERING. 
 
 quired form. The lime of the mortar changed to carbonate 
 of lime, which cemented firmly the grains of sand into a 
 hard rock. 
 
 It destroys organisms to whitewash. It would seem, there- 
 fore, that a plastered wall whitewashed was better than either 
 the "hard tinish" or papering. The accumulation of filth 
 in successive coats of papering in old houses is probably 
 frightful. Most of us have seen the trunks of trees white- 
 washed. This seems to me a misdirected effort to promote 
 health. Why should such indignity be practiced on our 
 noblest growths, stopping up the pores of the bark and 
 probably injuring the tree, in order to remove a little car- 
 bonic acid out of doors, where it is not in excess? 
 
 The Leaves of Plants as Purifiers. — The carbonic acid 
 thrown off into the air by decomposition, lighting, heating 
 and the breathing of animals, is taken up by the leaves of 
 growing plants, where it is decomposed, by aid of the sun's 
 rays; the carbon being appropriated to help make woody 
 fibre, &c., and the oxygen being given back to the air to fit 
 it for respiration. We cannot imitate this process in venti- 
 lation schemes, but have to resort to heated currents or to 
 fans to expel the foul air from our rooms and leaye it to 
 nature to carry the foul air by the winds to her millions of 
 laboratories and return it to us pure. If there was no vege- 
 table growth, however, it has been computed that the 
 breathing of animals would not vitiate the air perceptibly, 
 over the whole globe, in some thousands of years. 
 
 Limit to Ventilation Schemes. — It is impossible to 
 change the air, iidth comfort, in a room, as often as the winds 
 do, out of doors; but we can easily prevent the air in the 
 rooms from becoming too impure to breathe. Even when 
 there is no special attention paid to ventilation, it is found 
 that the hotter inside air is going out continually, thi-ough 
 every possible outlet, and cool fresh air coming in to take 
 its place. In very open houses, ventilation is often secured 
 
VENTILATION. 23 
 
 by the poor construction, in spite of the inmates, but it is 
 often at the sacrifice of comfort. 
 
 Ventilation by the Open Fire-place. — Let us now con- 
 sider one method of supplying pure air to a room contain- 
 ing an open fire-place. A fire must be kept brightly burn- 
 ing in the fire-place, to heat the air in the chimney or flue, 
 causing a difference of pressure in the external and internal 
 air, so that the out-door air rushes in through every crack 
 and crevice, even through the solid walls, and thus forces the 
 foul air up the chimney. 
 
 It is found, however, by experience, that the openings 
 mentioned are not generally sufficient to admit a sufficient 
 volume of pure air. Hence our custom is, at intervals, 
 when headaches or debility are experienced, to open the 
 doors or windows " to let in a little fresh air." A wise pre- 
 caution certainly; but it does not meet the whole case, for 
 air should be admitted without draft — i. e., without the influx 
 of sharply defined cold currents, which, as is well known, 
 produce colds, with their attendant evils. The problem has 
 been solved, however, in several ways, the details of which 
 are simple in the extreme. 
 
 Thus, if the lower sash of the window is raised a few 
 inches and the opening belo^is4t is completely closed by a 
 strip of plank, there will still remain an opening between 
 the sashes where they overlap, through which the air will 
 pour, being necessarily directed upwards. It thus strikes 
 the ceiling, and is then gradually diffused through the 
 room without draft. 
 
 A common expedient of simply lowering the top sash al- 
 lows the cold air to " trickle down" on our heads. In the 
 latter case, however, a board may be placed at an inclina- 
 tion against the upper part of the sash, so as to give the en- 
 tering current an upward direction. 
 
 Either of these plans is liable to failure when curtains or 
 blinds are used. So that a more generally applicable 
 method would consist in boring holes through the upper 
 
24 SANITARY ENGINEERING. 
 
 part of the doors or walls, and giving the entering air an up- 
 ward direction by means of inclined planes of some kind ; 
 or tubes of wood or iron may be passed through the walls 
 and turned directly upwards on entering. They should ex- 
 tend to at least 7 feet above the floor. 
 
 The air in all cases should be drawn directly from out- 
 doors, and not from passages or other rooms. The open- 
 ings, moreover, should admit of being partially or entirely 
 closed on very stormy and windy days. Ail of the above 
 plans have been tried in dwellings, club rooms, etc., with 
 complete success. 
 
 The proper size of tube or opening to use must be deter- 
 mined by experience. Two tubes, of two inches diameter 
 each, may be tried for an average-sized room for two per- 
 sons. It is stated that "two square tubes, 5x5 inches, will 
 keep a good-sized club-room fresh." 
 
 Now, this method of ventilation is dependent upon a fire 
 being maintained at the lower level of the room to cause 
 the currents to enter with sufficient velocity. The system 
 fails in summer; when, however, we do not object to the 
 draft caused by opening the doors and windows. 
 
 Known Properties of Air. — The mathematics of this 
 branch of the subject, (which is not given, as it seems out 
 of place here,) depends upon certain known properties of 
 air which may be briefly mentioned. Thus 12.4 cubic feet 
 of air weighs 1 pound, when at a temperature of 32° P, 
 the barometric height being about 30 inches, the average 
 pressure at the sea level. 
 
 Since air is compressible, (its volume varying inversely 
 as the pressure,) it follows that as we ascend, the weight of 
 tlie same volume of air becomes less, since there is less air 
 above us than before, so that the same weight of air is not 
 compressed into so small a place. 
 
 Air likewise expands or contracts 1-491 part of its volume 
 for each degree Fahrenheit above or below the frezing point, 
 the pressure remaining the same; so that 491 volumes of 
 
VENTILATION. 25 
 
 air at 32° becomes 499 volumes at 40°, 509 at 50°, 519 at 
 60°, 529 at 70°, 539 at 80°, and 549 volumes at 90°, whilst 
 the 491 volumes at 32° F. become 479 at 20°, 469 at 10°, and 
 459 at 0° Fahrenheit. 
 
 Again, it is found that one pound of air can be raised 
 1° F. by the same amount of heat that will raise 0.2874 lbs. 
 of water through one degree, the air being subjected to con- 
 stant pressure. 
 
 From such data, in connection with the heat afforded by 
 different fuels, and the laws affecting the flow of gases, we 
 are enabled to compute the velocity of the air flowing out 
 of the chimney, which is thus a measure of the inflow of 
 the fresh air. Suffice it to say that the higher the chimney 
 or flue the stronger the draught, as thereby the difference 
 of weights of the heated air in the chimney and a similar 
 column outside the chimney is greater. 
 
 Ventilation by Gas Jets. — In theatres and closed halls, 
 a series of gas jets may be used to create a current, the 
 heated air passing outdoors through flues placed directly 
 over the gas jets. 
 
 It is stated that this plan has met with great success in 
 two churches in New York, the size of one of them (Dr. 
 Scudder's church) being 150x100, of the other (Dr. Hep- 
 worth's) 125x125 ; the first seating 2,200 and the second 
 2,400. There were 14 to 20, 12 inch round tin pipes, carried 
 up in walls from near the floor to and above the roof. In 
 each of these tubes was placed three gas burners, just above 
 the registers that admit air from the outside. On simply 
 heating some of these gas jets, the registers being opened 
 the proper amount, there is caused a quick exhaust, under 
 complete control, and an inflow of pure fresh air. There i? 
 an opening in the centre of the ceiling of the auditorium 
 into an octagon shaped shaft 11 feet in diameter in one 
 church, 16 in the other, extending above roof, containing 
 sashes and outlets to the outer air. Gas jets are placed 
 under tubes in these shafts to increase the current. At 
 other parts of the ceiling are similar shafts, etc. The nu- 
 
26 SANITARY ENGINEERING. 
 
 merous gas jets produce such a current that, in warm weather, 
 the entire air of the church can be changed every five 
 minutes. The churches are heated by hot air furnaces or 
 steam coils. (See "Plumber and Sanitary Engineer," March, 
 1879.) 
 
 Ventilation by Fans. — Still another method of ventila- 
 tion is by pumps and fans. Most generally, air is drawn 
 from without by fans located in the basement, and is pro- 
 pelled along ducts — over steam pipes or furnaces, if it is to 
 be heated — to openings into the various halls and rooms, 
 from whence it escapes by suitable openings, generally 
 placed in the roof. The air is often drawn from near the 
 ground, but it is best, especially in densely populated 
 cities, to draw the fresh air from a point 100 to 200 
 feet above the ground down vertical shafts. In Paris, the 
 air is drawn down a shaft 180 feet in height, to supply the 
 Assembly room. (See Appendix III for a description of 
 the ventilation of the N. Y. Lunatic Asylum.) 
 
 Good Effects of Ventilation. — It is evident how im- 
 portant a factor of health ventilation is in crowded school 
 rooms ; in fact in all places where crowds may congregate 
 and speedly vitiate the air. The bad effects are everywhere 
 admitted. The good effects of the systems proposed have 
 been proved by mortuary statistics, especially in school 
 houses and hospitals. In a Dublin hospital, in 1783, for 
 ■ 25 years when the ventilation was bad, 3,000 out of 18,- 
 000 children, born there, died within the first fortnight of 
 their birth. With better ventilation in the succeeding 28 
 years, 550 died out of every 15,072. 
 
 The report of 1861 states that further improvements in 
 ventilation have been made, and deaths from the " nine-day 
 fits," which carried off most of the infants, was then almost 
 unknown. 
 
 The records concerning ventilation in connection with 
 lung diseases is equally striking. Such diseases thrive in 
 cities where the smoke resulting from the burning of coal 
 
VENTILATION. 27 
 
 is charged with impurities, such as " hydrocarbons, sulphide 
 of ammonium, carbonic oxide, and probably very minute 
 quantities of arsenic." Even now the cry is going up from 
 London for a purification of its atmosphere from smoke. 
 This gvil we do not suffer much from in North Carolina, 
 the population being scattered and the cities small. But 
 we need a thorough inspection of public buildings with a 
 view to proper ventilation. 
 
 When it is known that 30 parts of carbonic acid to 10,000 
 of air is often found in theatres and public halls, which is 
 five times the admissible amount, it will be admitted that 
 reform is needed. 
 
 Cubic Space Allowed. — The amount of space per head 
 allowed in the room by various authorities, varies from 300 to 
 1,000 cubic feet, the amount being smaller when the room 
 is only occasionally filled with its maximum number. 
 
 It is true that the air can be changed in a small room 
 more frequently than in a large one to maintain the proper 
 degree of purity or rather impurity, but the increased 
 draught may be objectionable. The amount of space act- 
 ually given -per head in various school houses varies from 70 
 to 100 to 200 cubic feet. The effect is that 12 parts of car- 
 bonic acid in 10,000 (double the admissible amount) is com- 
 mon, and even 20 and 50 parts are not unknown. The 
 effect upon both teacher and pupils is of course, headaches, 
 listlessuess and debility. 
 
 Lighting. — The proper lighting of school rooms is as 
 necessary as ventilation. The light should come from 6e- 
 hind the pupil on to the book or blackboard, when possible, 
 and the windows should be high, as most of the available 
 light comes from above the level of our heads. Lighting 
 directly from the top is probably the most efficient means 
 of all where practicable. The light should come mainly 
 from one side — the side opposite the blackboards — and the 
 pupils should sit with their backs to it. The desks should 
 be at such heights that the book or paper, &c., shall not be 
 
28 SANITAKY ENGINEERING. 
 
 too near the eyes, so that the tendency to near-sightedness 
 may be prevented. This defect is becoming alarmingly 
 prevalent, and the teacher should insist upon the pupil 
 reading with the book at the proper distance to suit his 
 vision, at all times. 
 
 Useful Hints. — Finally, let it be impressed upon all 
 that the sense of smell when coming from outdoors into a 
 room should warn us when our rooms are foul, and that 
 doors and windows should be opened when convenient, and 
 articles of clothing and bedding should be aired frequently 
 to purify them. 
 
 Also let it be remembered that even brick walls can trans- 
 mit gases. "Pettenkofer got 2,650 to 3,320 cubit feet of air 
 through the brick walls and crannies of his room, when the 
 difference of temperature inside and outside was 34° F. 
 When all the crannies had been carefully stopped up, 1,000 
 cubic feet per hour still came through the walls." There- 
 fore never allow filth about any room or cellar of the house, 
 nor against the outside walls, for such filth will contami- 
 nate the air that comes into the room, and has been found 
 to cause sickness. If the house is liable to such contagion 
 from adjoining buildings, endeavor to make it as air tight 
 as possible, after providing for the admittance of the purest 
 air that can be obtained through proper openings. The 
 floors of all houses should be as tight as possible. 
 
 Heating. — Intimately connected with ventilation is heat- 
 ing; in fact the two have generally to be considered to- 
 gether. In cold weather we require more heat than our 
 bodies generate to make up for the loss by radiation ; at the 
 same time we need fresh air to breathe. 
 
 How admirably are these two conditions realized around 
 a good camp fire, on a still, cool night! The active worker 
 has just enjoyed his hearty meal, as only a worker can, and 
 with feet stretched to the fire — that heats him by direct 
 radiation — and body well clad, inspires the cool, fresh air 
 of the country thdt invigorates body and mind. 
 
VENTILATION. 29 
 
 Cool air to breathe is as refreshing as cool water to drink, 
 whilst air too warm may be compared with tepid water in 
 its effects. This fact is universally admitted, and yet it has 
 got to be the fashion, at the North especially, to heat houses 
 by puffs of hot air from furnaces that would seem more 
 properly in keeping with a drying house. Let us under- 
 stand clearly the physical differences in the various methods 
 of heating, and we can then form a more intelligent judg- 
 ment as to the merits or demerits of each particular device. 
 
 The open fire heats solid bodies in front of it, by direct 
 radiation of heat raj's, which pass through the intervening 
 air with scarcely any loss. Tyndall has shown that air, 
 consisting simply of oxygen and nitrogen, intercepls but 
 an extremely small number of heat ra3'S passing through 
 it. The aqueous vapour, found in all air, intercepts 20 to 
 100 times the heat that pure air does. Carbonic acid, per- 
 fumes, etc., increase the absorption of heat by air. The 
 water gas in the atmosphere, although constituting only, 
 say ^ per cent, of it, yet intercepts nearly all the heat rays 
 of the sun that do not reach the earth ; and again prevents 
 their too rapid radiation at night from the earth. As Tyn- 
 dall says, " Aqueous vapour is a blanket, more necessary to 
 the vegetable life of England than clothing is to man." 
 The amount of heat, however, intercepted by the air be- 
 tween the fire of a room and solid objects in front of it, 
 although small, yet does increase the temperature of the air 
 somewhat, though it is usually neglected altogether. The 
 air of the room is mainly warmed by " convection," from 
 coming in contact with the solid objects that have a higher 
 temperature ; the air next the solid body being heated first, 
 then rises, to be replaced by other air, which operation is 
 repeated indefinitely, or until the whole mass is heated to 
 the same temperature. 
 
 There is thus a continual circulation of the air in a room 
 heated by an open fire place, and generally an eflBcient 
 draught to keep the air from being too much fouled. 
 
30 SANITAEY ENGINEEEING. 
 
 If the room is heated by steam or hot-water pipes, the 
 case is different. The direct radiation is small, as any one 
 can test by trying to warm his feet at the pipes without 
 actual contact. The warming is mainly effected, as in the 
 case of STOVES (not over-heated) or hot-air furnaces, by the 
 air being warmed, by the heated pipes, stoves or furnaces, 
 by convection, and this air by its circulation heats the room 
 and its occupants. The air is thus warmer than the furni- 
 ture in the room ; whereas in heating by the open fire-place, 
 the furniture, etc., is ofteji warmer than the air. A person 
 in the room would thus be continually radiating heat, un- 
 less the air was too warm for comfort. In addition to the 
 objection to the warm air, per se, it has been previously ex- 
 plained that heating air causes it to become too dry; so that 
 whilst the " relative humidity" out of doors may be 80, in 
 doors it may be much less — a disproportion that cannot be 
 conducive to health. In fact, asa writer humorously remarks, 
 such drying houses " are drying the very flesh off the bones 
 of the Americans." 
 
 Still, in large buildings it is generally impracticable to 
 heat by direct radiation, and the inmates have to submit to 
 be dried. Again it is stated that the rigor of the Northern 
 climate. requires that the air, even in dwelling-houses, be 
 heated somewhat before being admitted, If so, then it is 
 still practicable to heat it only to 50° or 70° F., and supple- 
 ment with the open fire-place. 
 
 Summary of Modes of Heating in the Order of Merit. 
 — We shall conclude this popular exposition of the subject 
 by a condensed summary of the various modes of heating 
 in vogue, in the same order of merit as that given by Prof. 
 Fleming Jenkin, in " Healthy Houses" (Harpers Half Hour 
 Series), a book that every one should have. 
 
 The open fire-place is best, although most expensive, as it 
 heats by radiation, and secures ventilation. 
 
 Next follow, in the order of descending merit, hot water 
 pipes, porcelain stoves, hot air pipes, cast iron stoves, and 
 
VENTILATION. 31 
 
 last and worst gas-stoves with no. chimney. These pipes 
 and stoves heat largely by convection — i. e., by heating the 
 air next to them, which rises and is difFased through the 
 room, the cold air taking its place to be in turn heated, &c. 
 
 Iron stoves, especially when over-heated, emit a bad smell, 
 supposed to arise from the charring or decomposition of or- 
 ganic substances in the air by their contact with the heated 
 sides of the stove and pipe. Moreover, if the stove is red 
 hot, the poisonous carbonic oxide and other gases will pass 
 through the red hot iron and thus enter the room. The air 
 is charred and dried too much b}' iron stoves. The porce- 
 lain are far preferable. Hot air pipes are better, and more- 
 over distribute the heat more uniformly; though if the fur- 
 nace becomes red hot, poisonous carbonic oxide will pass 
 into the pipes. Some describe the "hot air" as having the 
 " life taken out of it." Hot water pipes are better than hot 
 air pipes; the air is not over-heated, and a uniform temper- 
 ature is preserved for a long time. It is much used in hot- 
 houses, baths, drying-rooms, etc. 
 
 Exits must be provided for the foul air where the hot-air 
 system, the water pipes or the gas-stoves are used. For 
 comfort and cheerfulness, no device can equal the open fire- 
 place, fed with coal, or oak and hickory wood, not ignoring 
 either the historic pine. 
 
 The fresh air then comes in through the, walls, tubes, etc., 
 cold, with plenty of oxygen and perhaps ozone in it, and is 
 gradually diffused through the room as it becomes heated, 
 to give up the proper amount of oxygen required for respi- 
 ration and combustion. What excuse can there be for close 
 rooms, that breed debility of various kinds, when pure, fresh 
 air can be obtained by us at such a small cost ? 
 
32 SANITARY ENGINEERING. 
 
 CHAPTER IV. 
 WATER SUPPLY. 
 
 All of our supplies of water are derived from rainfall, 
 part of this rainfall evaporating again, part running off into 
 the streams and thence into the ocean to be again distilled 
 and sent back to us as clouds and rain, and part sinking 
 into the earth and forming the small subterranean streams 
 virhich furnish the water of our springs and wells. In run- 
 ning over or through the ground, this water takes up such 
 salts as it meets that are soluble. Some of these, together 
 with the air and carbonic acid dissolved, giving the pleasant 
 taste to our usual potable waters. 
 
 Other salts and gases, derived from decaying organic mat- 
 ter — dead bodies, manure, filth, etc. — are harmful in the 
 highest degree, and have bred mischief and death in innu- 
 merable cases. 
 
 The rain as it leaves the clouds is pure water generally ; 
 but in falling to the ground, it not only carries with it me- 
 chanically much organic matter and dust that is floating in 
 the air, but it dissolves various gases, as oxygen, nitrogen, 
 carbonic acid and ammonia (the usual constituents of the 
 atmosphere) besides nitric acid (often formed in the air by 
 the lightning's flash), and in the vicinity of manufacturing 
 towns, the gases evolved in tlie processes used in the partic- 
 ular manufacture. Water readily dissolves certain gases. 
 On simply shaking it up with air, the latter is readily dis- 
 solved. This principle is made use of in aerating the pure 
 water, that has been distilled from the salt water of the ocean, 
 on board ships, thus making it drinkable. 
 
 The amount of oxygen, nitrogen, carbonic acid and am- 
 monia commonly found in waters is small, particularly the 
 ammonia; which last, it may be observed, water can dis- 
 
WATER SUPPLY. 33 
 
 solve in large quantities. All of these gases are easily ex- 
 pelled by simply boiling the water. 
 
 Rain water generally contains far less organic metter than 
 river water. River waters, though, differ greatly in the 
 amount and character of the matter, in solution and sus- 
 pension, as regards potability. Thus, if water drains over 
 an impervious stratum, as a granitic formation, the water is 
 apt to be soft, and to contain but little solid matter in solu- 
 tion. Some waters of this character contain only from three 
 to five grains of solid matter to the gallon ; they possess a 
 high solvent power on lead and iron pipes, but are other- 
 wise of the best character. 
 
 Where the rocks consist largely of carbonates of lime or 
 magnesia, the waters are apt to be hard, their action on leadi 
 and iron pipes is small, and they require a greater expendi, 
 ture of soap in washing, but are not otherwise objectiona- 
 ble, unless the carbonates are greatly in excess. 
 
 It is stated that the health and physique of hard water 
 districts is better than in soft water districts ; the water fur- 
 nishing an abundance of material needed in the formation 
 of the bones. 
 
 Each " degree of hardness " {i. e., each grain of chalk or 
 sulphate of lime, dissolved in a gallon of water) will entail, 
 however, the additional use of two-and-a-half ounces of 
 soap for every 100 gallons of water ; so that it is well to get 
 rid of the carbonates in solution, if possible. This may be 
 partially effected in two ways ; either by boiling the water, 
 or by adding milk of lime. Both methods depend on the 
 fact that water can dissolve only two grains per gallon of. 
 carbonate of lime, unless it contains carbonic acid in solu- 
 tion, when it can dissolve very much more. 
 
 Boiling expels this acid; thus reducing the amount of 
 carbonate of lime in the water in solution to, at most, two 
 grains per gallon. By the second, called " Clarke's process," 
 the added lime-water combines chemically with all the free 
 carbonic acid, forming carbonate of lime, which thus settles- 
 8 
 
34 SANITARY ENGINEERING. 
 
 to the bottom, together with much of the original carbonate 
 of lime, leaving only about two grains per gallon still in 
 solution of carbonate of lime. 
 
 The milk of lime is made by shaking up a small quan- 
 tity of quick lime in water. 
 
 Permanent hardness of water is caused hj the presence 
 ■of sulphates of lime and magnesia. Neither boiling nor 
 ■Clarke's process can soften such water. 
 
 Wells and Springs. — Where wells or springs are used as 
 the source of water supply, great care should be taken that 
 the surface in their vicinity be kept free from organic mat- 
 ier, which by oxidation and putrefaction readily forms solu- 
 ble nitrates, ammonia and chlorides. 
 
 Such waters are often clear, pleasant to the taste, sparkling from 
 the excess of carbonic acid and cool from the effects of the nitrates. 
 Hence the senses cannot be relied on, without the aid of a 
 .chemical and microscopical analysis to decide whether our 
 well water is fit to drink. Even when all filth, slops, etc., 
 are removed to a distance, we can only infer that there is 
 no probable contamination. 
 
 The geological structure — stratification, faults, character 
 of the earth, etc. — should be studied in this connection. 
 Thus it was found in a certain locality that wells very near 
 a grave yard gave good water, whereas wells on the oppo- 
 site side, several hundred yards off, in the direction of the 
 ;dip of the strata, were polluted to a dangerous extent. The 
 explanation is simply that water has a tendency to flow 
 along the planes of stratification, where the strata are well 
 defined. 
 
 Numerous cases of fever, cholera, &c., have been traced 
 to bad water; localities with wells situated on the subter- 
 ranean current that flowed past the diseased refuse, cess 
 pool, etc., being attacked, whilst neighboring localities were 
 free from the epidemic. It is needless to specify particular 
 instances. Let no wells be placed where kitchen refuse, 
 jslops, manure or any kind of fecal matter can drain into 
 
WATER SUPPLY. 35 
 
 them. Where no stratification exists, tiien, if possible, 
 place the well two or three times its depth from any offend- 
 ing matter. A well can just as properly be dug next to the 
 house as elsewhere, provided slops and kitchen refuse are 
 emptied some distance from it. In one instance soapy water 
 was found by analysis in one well, whose sparkling waters 
 would never have suggested it. The whole of the slops of 
 the establishment were thrown where they drained .directly 
 into the well. 
 
 It must be carefully borne in mind that the well is the 
 point of least resistance to the numerous little streams en- 
 tering it and that it may induce a flow from a considerable 
 extent of the surrounding earth. Chemical analysis can 
 alone show if some of these little streams have been pol- 
 luted ; in fact, whether a well is the drainage receptacle of 
 the filth on the surface or of the rotten cess pool — the dis- 
 grace of any land where it is found. 
 
 It is not intended to convey the idea that, before wells 
 are dug, the underground water is necessarily flowing in 
 little streams. On the contrary it is generally otherwise, 
 particularly in very absorptive strata. Very hard rocks, of 
 course, hold but little water, except in the crevices, whilst 
 very porous and absorptive strata, as the London chalk, are 
 fully saturated with water from near the surface downwards 
 and only need tapping to afford it in large quantities. 
 
 The water thus contained in the ground is known as the 
 " soil " or " ground " water. Where the earth is porous, 
 absorptive and uniform in character, much more of the 
 rain water passes into the ground to flow off along subter- 
 ranean channels to some outlet, to appear at the surface 
 again as ^rings, or to be pumped out of wells — than where 
 the surface is more impervious. 
 
 The imaginary line connecting the water level of springs 
 and wells (when not used) is called "the line of saturation." 
 It has been found that in uniform earth this line of satura- 
 tion generally rises with the ground, so that generally as 
 
36 SANITARY ElNGlNEERING. 
 
 we recede from the sea-coast, or a stream, the water level of 
 the well rises, whilst its depth beneath the surface increases. 
 This rule is often true even when there is a want of uni- 
 formity in the strata or in the configuration of the ground> 
 though so much depends upon the inclination the beds 
 have, and their relative permeability, that it is impossible 
 to lay down any precise rules as to where water may be 
 struck in any but the simplest cases. 
 
 This is still more evident if the rocks are contorted, fis- 
 stired or faulted. 
 
 Some special eases may be given however. Thus if a 
 porous stratum overlies an impervious one, the water de- 
 scends through the former until it reaches the latter. Now 
 as the lower stratum is level, or slopes towards its outcrops, 
 or is depressed in tlie middle, the water which soaks through 
 the porous stratum will eventually appear in the form of 
 springs near the upper line of the outcrop of the lower 
 stratum, or be mostly stored in the depression mentioned of 
 this stratum. Unless the porous stratum is very shallow, 
 wells may be dug in it, especially in the last case mentioned, 
 with the expectation of getting a good supply of water. 
 
 Where the porous stratum is covered ^by an impervious 
 one, it holds less water than in the previous case, for it now 
 receives no water except along its outcrop. 
 
 Where such porous strata, however, are of great extent 
 and have a considerable outcrop (it may be in remote dis- 
 tricts) a good supply of water may he expected. 
 
 In the latter case, if the porous stratum is again underlaid 
 with an im>pervious one which is depressed in the middle, 
 large quantities of water will collect in this basin under 
 considerable hydrostatatic pressure. If this pressure is 
 sufficient to send water to the surface through a well hole, 
 the result is an artesian well, which wells are much re- 
 sorted to in some couatries. 
 
 In this State we need have no fearsof a water famine if th& 
 various sources are utilized. In the Quartersary sand Of 
 
WATER SUPPLY. 37 
 
 the eastern portion of the State, wells only 15 feet deep are 
 common, though the underlying Tertiary marls and older 
 rocks may cause exceptional features. In the middle and 
 western portion of the State, the rocks are sandstones, slates 
 and various crystalline rocks, which are often fissured, 
 faulted, contorted or intersected by trap dykes ; thus caus- 
 ing abnormal features : still, as the dip except in the sand- 
 stone formation is often considerable, there is not generally 
 much difficulty in finding water on digging for it; so that 
 the " diviner " with his witch hazel twig generally finds his 
 predictions verified. Perhaps it would be the same if he 
 did not invoke its mysterious powers to assist him ! In the 
 older rocks, the water often collects in fissures. Instances 
 are known where pumping from one well affects a remote 
 one ; whilst, on the other hand, owing to faults, dykes, 
 change of dip, etc., wells very near together seem to have 
 no connection. 
 
 As a rule, the wells are deeper in the older rocks ; for, as 
 the latter are more impervious than the sands of the later 
 formations, less water is absorbed by them — more running 
 off into the streams — therefore we should naturally expect 
 to go deeper for a constant supply. Other things being 
 equal, the deeper the well the purer the water, as it has 
 filtered through a greater extent of earth. 
 
 The earth is thus a vast sponge, ready to afford water 
 when tapped, that is generally of a better quality too than 
 lake or river water in the vicinity. 
 
 Prof. Nichols (see " Filtration of Potable Waters,") has 
 observed, that even when the well is situated near a stream, 
 that " the water is generally clear and colorless, of a nearly 
 uniform temperature, and differs in chemical character from 
 that of neighboring streams or ponds, generally being some- 
 what harder." 
 
 On lowering the level of the water in such basing by 
 pumping or otherwise, the ground water level is lowered 
 next the basin to the same extent ; but it is found that as 
 
38 SANITARY ENGINEERING. 
 
 we proceed from the well or basin, that this level is lowered 
 less and less, until we reach a point which is not aflfected 
 when the level of the water in the basin is kept at a certain 
 minimum height, the friction and capillarity balancing 
 gravity here ; supposing always the rain fall not subject 
 to much variation. In case of drought, of course the whole 
 ground water level would be lowered. 
 
 As an illustration of the above principle, it was found on 
 the Elbe, that when the water in a well, dug in an alluvial 
 deposit, was kept constanly 8.2 feet below its normal level, 
 that the height of the ground-water was affected in every 
 directinn for 200 feet only. 
 
 Large basins, near streams, are often used as the source 
 of water supply of whole towns. Now it is evident that if 
 the water level is lowered in such a basin that since the 
 water level in the intervening bank is lowered, that the 
 river water will have a tendency to flow towards the well 
 to make up the deficiency, unless the bottom and sides of 
 the river have become coated with clay to such an extent as 
 to be impervious, which is very apt to be the case unless the 
 stream is very clear, or has a rapid current. Known ex- 
 amples seem to show little or no contamination from the 
 river water when the basins are built 100 to 200 feet from 
 the river. The basin is constructed next a stream, as there 
 is apt to be a greater flow of ground water there ; besides 
 the water in the stream can make up any deficiency by use 
 of proper constructions. 
 
 Filtration. — This natural filtration of water through the 
 soil, when the latter is good, is more efficient than any sys- 
 tem of ARTIFICIAL FILTRATION, which, when practiced on a 
 large scale, generally consists in passing water through 
 layers of sand and gravel about six feet deep. The finest 
 sand is put at the top, the upper portion of which catches 
 most of the suspended matters, and by the oxygen con- 
 densed in its pores, frees the water of a small portion of its 
 organic matter. 
 
WATEK SUPPLY. 39 
 
 As the sand becomes clogged, it is scraped off at top ai{d 
 fresh sand added. 
 
 It is well not to cause the water to flow through the filter 
 at a rate greater than fifty gallons per square foot of surface 
 per day. The water is usually several feet deep on the filter 
 bed. The beds are scraped about a dozen times a year, 
 oftener in summer than in winter. 
 
 When possible, it is best to construct settling-basins where 
 the water can deposit much of its sediment before passing 
 on to the filter beds. 
 
 In some rivers, the particles of clay in suspension are so 
 fine as to readily pass through sand and even filter paper. 
 In such cases, charcoal pounded fine is the only resource. 
 The action of a sand filter is two fold, mechanical and 
 chemical: 
 
 1st. Mechanical, in that suspended matters too large to 
 pass through the pores of the filter are caught, as in a net ; 
 likewise much sediment that would otherwise pass through 
 sticks to the grains of sand, due to the property of adhesion. 
 
 2nd. Chemical, for although sand filters have practically 
 no action on dissolved mineral matter, yet an appreciable 
 quantity of organic matter in solution, particularly certain 
 kinds, are removed by filtration through them. 
 
 An experiment that any one can perform will illustrate 
 this : Add a few drops of sulphate of indigo solution to some 
 clear water ; the water assumes an intense blue color, Mhich 
 color it retains on filtering through an ordinary filtering 
 paper. But if we strew over the filter paper some powdered 
 charcoal (animal charcoal is best) the water comes through 
 perfectly colorless. If we use earth in place of the charcoal, 
 the water that passes through it ife slightly colored, thus 
 showing that earth is not so powerful an agent as charcoal. 
 Now, evidently, here the earth or the charcoal have exer- 
 cised a different influence from the filter paper alone. The 
 filter paper will catch suspended matter. Thus mudd}' water 
 passed through it may become clear, but it does not alter 
 
40 SANITARY ENGINEERING. 
 
 chemically the substance in solution. We have just seen, 
 though, that earth or charcoal does, and the usual hypothe- 
 sis to account for this fact is that " porous substances con- 
 dense gases — air, osygen, etc., in proportion to the extent of 
 their interior surface," and this oxygen actually destroys by 
 slow combustion the substance in question. The enormous 
 amount of surface to volume of porous charcoal or piles of 
 earth permits the condensation of a large amount of gas 
 which stands ready to attack any chemical body that can be 
 decomposed or altered by it. 
 
 Of course this chemical action must diminish the more 
 the longer the filter is in action, as the oxygen is not so 
 readily replaced when the filter is covered with water. If 
 water is really poUuted by sewage matters, it has been shown 
 that it may be improved materially but not perfectly puri- 
 fied by filtration. It is, therefore, pertinent to ask, what 
 amount and kinds of organic matter found in water render 
 it unfit for drinking? 
 
 Evidently, we must consider the two questions together. 
 Organic matter, per se, cannot always be deleterious, other- 
 wise soup would have to be ranked as poison. It is stated 
 that the waters of the Dismal Swamp, saturated with or- 
 ganic matter, is actually preferred by sea-going vessels to 
 purer waters. Chemistry is perfectly able to determine the 
 mineral salts dissolved in water, and medicine can pro- 
 nounce upon the amounts that may be taken into the sys- 
 tem without injury. Chemistry can likewise determine the 
 amounts and kinds of organic matter in any water, and if 
 the source is known to be bad, or the organic matter (espe- 
 cially the albuminoids) in excess over good potable waters 
 in the vicinity, the chemist is able to form an intelligent 
 opinion, at least as to the " possible amount of germ " or 
 disease producing power of the water. 
 
 London drinks Thames water principally, though "above 
 the point where the supply is abstracted the river is contami- 
 nated by the excrements of more than 200,000 human beings." 
 
WATER SUPPLY. 41 
 
 Those who favor this water, claim that a polluted river 
 purifies itself in its onward flow, the noxious matter being 
 oxidized as it is tossed to and fro by the current and thus 
 rendered innocuous, besides being more and more diluted. 
 Again, fish eat fresh fecal matter, and vegetation can ab- 
 stract large quantities of it. Still, it is doubtful if this nat- 
 ural process is continued long enough to thoroughly destroy 
 the hurtful part of the sewage. 
 
 Now can this Thames water be regarded as a fit source 
 for water supply, having once been contaminated to a cer- 
 tain extent ? " The noxious part of sewage is that which is 
 held in mechanical suspension, and these globules are be- 
 yond the reach of the chemist, and, to a great extent, of the 
 microscopist. There are only two processes by which it can 
 be effectually removed ; the one is boiling for a long time, 
 and the other is by distillation, both impracticable on a 
 large scale." " No process of filtration that has yet been 
 devised will remove choleraic dejections from water." (Hum- 
 ber's Water Supply, p. 19.) 
 
 The organic matter is not then considered as fatal in 
 itself, but as dangerous, when of certain kinds, as affording 
 a refuge and breeding ground for the poison germs that 
 attend an epidemic. A person may drink even diluted 
 sewage with but slight inconvenience until this germ is 
 once planted in it, when at ohce his beverage changes to a 
 rank poison. 
 
 Whether we accept the germ theory or not, it is admitted 
 that drinking foul water and breathing impure air debili- 
 tate the system and thus render it less able to withstand 
 epidemics. Let us then follow the natural instincts and 
 avoid polluted air and water, especidly as North Carolina 
 can afford the pure articles in such abundance. 
 
 Lead Poisoning. — There is one source of poisoning that 
 may be considered by itself — lead poisoning, due to the use 
 of lead cisterns and lead pipes. 
 
42 SANITARY ENGINEERING. 
 
 Soft waters that contain oxygen oxidize the lead and then 
 dissolve the lead oxide formed. Hard waters, containing 
 free carbonic acid, form, on the contrary, carbonate of lead, 
 which is only soluble to the extent of one part in seven 
 thousand, unless there is much free carbonic acid present. 
 Clarke's softening process lessens the action of water on lead. 
 Peaty matters form a sort of protecting coating on the lead 
 pipe that is very eflScacious in preventing further action on 
 the lead. One-tenth of a grain of lead per gallon of water 
 may produce lead poisoning in time. 
 
 The presence of lead in water is easily detected by passing 
 a current of sulphuretted hydrogen through a deep column 
 of the acidified water. If the liquid becomes tinged of a 
 brown color, it is due to the formation of lead sulphide. 
 What is the remedy if the water is found to act continuously 
 on the lead ? Simply abolish the lead cisterns for slate, or 
 stone ware, or galvanized iron cisterns, and replace the lead 
 pipes by wrought iron pipes with screw joints. The tin 
 lined lead pipe has not proved satisfactory ; a small flaw 
 exposes the lead, a galvanic action between the two metals 
 is commenced and the water is speedily poisoned. 
 
 It is of the greatest importance to observe that no cistern 
 or water pipes should be placed where sewer gases may pass 
 either through or over them, in contact with the water, since 
 water is very absorbent of such gases. 
 
 Cistern Water. — Where rain water is used as the source 
 of supply, it is collected from the house roofs and stored in 
 cisterns of wood or brick in cement. The cistern, if of wood, 
 should have a circular form ; if of brick, any convenient 
 form can be used, provided the earth is well rammed behind 
 the walls, to enable the latter to withstand the outward pres- 
 sure of the water. The cistern should be covered and ven- 
 tilated. 
 
 The rain water as it descends brings down many impu- 
 rities from the atmosphere, such as soot, acid fumes, oil, etc., 
 particularly in the manufacturing centres; besides if or- 
 
WATER SUPPLY. 43 
 
 ganic impurities in the shape of dust, such As horse ma- 
 nure, etc., cover the roof, the watter is further contaminated 
 before it reaches the cistern. The character of the roof like- 
 wise, whether lead painted, formed of new shingles or de- 
 cayed ones, etc., must be considered. We thois see that cis- 
 tern water is not necessarily perfect, though it is probably 
 better than well waters, for while it has not had the benefit 
 of the natural filtration of the latter, still it has taken up no 
 new salts from the ground, and has certainly escaped sew- 
 age contamination. 
 
 Nevertheless, it should be filtered before being used. This 
 is effected in various ways. One plan, when the brick cis- 
 tern is used, is to divide the cistern by a porous wall into 
 two unequal parts. The foul water, let into the larger divi- 
 sion, filters through the porous wall into the smaller divi- 
 sion, from whence it is pumped over the house. The po- 
 rous wall may be made of soft bricks, or of some filtering 
 material, as porous tiles or blocks of animal (bone) charcoal, 
 that may be placed in a frame which can slide in groves 
 and be readily replaced when the filter has become clogged 
 up. 
 
 The brick wall, although very efiicient at first, becomes 
 clogged up in a few months by solid matter, consisting, 
 amongst other things, of insects, worms, etc.; so that the fil- 
 tration then is rather an injury than a benefit, as chemical 
 analysis has demonstrated. The solid matters that settle at 
 the bottom of cisterns should, of course, be removed when- 
 ever practicable. 
 
 Domestic Filters. — With regard to domestic filters of 
 any kind whatsoever, it may be observed that the filtering 
 material requires renewal every few months. 
 
 The following is an extract from the "Sixth Report of the 
 River Pollution Commissioners of England :" 
 
 " It cannot be too widely known that, as a rule, domestic 
 filters constructed with sand, or sand and wood charcoal. 
 
44 SANITARY ENGINEERING. 
 
 are nearly useless after the lapse of four months, and posi- 
 tively deleterious after the lapse of a year." 
 
 " Of all material for domestic filtration, with which we 
 have experimented, we find animal (bone) charcoal and 
 spongy iron to be the most effective in the removal of or- 
 ganic matter from water." 
 
 " The removal of mineral constituents, and the consequent 
 softening of the water, ceases in about a fortnight, but the 
 withdrawal of organic matter still continues, though to a 
 greatly diminished extent, when the filter is much used, 
 even after the lapse of six months." 
 
 " We found that myriads of minute worms were develop- 
 ed in the animal charcoal, and passed out with the water 
 when the filters were used for Thames water, and when the 
 charcoal was not renewed at sufficiently short intervals, a 
 serious drawback to its use." 
 
 The spongy iron is free from this trouble, but the filtered 
 water, especially the first portions filtered, contain iron ; and 
 the softer the water the more iron dissolved. 
 
 On the whole, it would seem that for hard waters "Bis- 
 chop's Spongy Iron Filter" is best, though the animal char- 
 coal is an admirable material, when renewed every few 
 months. Chemical analysis can alone tell when the filter 
 has ceased action. 
 
 Both materials (spongy iron and animal charcoal,) remove 
 about the same quantity of "albuminoid ammonia," say one 
 fourth, as a mean of some very careful experiments, (Nichols 
 on Filtration of Potable Water), this substance being taken 
 as the measure of the suspicious organic matter in solution 
 
 From an analysis by Bischof (Humber's Water Supply) 
 it would seem that the spongy iron (a metallic iron reduced 
 from an oxide without fusion, and hence in a loose spongy 
 state) was a more efficient agent than "magnetic carbide" 
 and "silicated carbon," two other materials that have been 
 used with success. 
 
 If animal charcoal is used, it should be in lumps in pref- 
 
WATER SUPPLY. 46 
 
 erence to blocks, though the latter gives good results. An 
 admirable filter, that may be used in any cistern, consists 
 of a metallic vessel with a perforated bottom, filled with an- 
 imal charcoal and having a pipe leading from the top, which 
 must be below the level of the water in the cistern. The 
 water of the cistern passes up through the perforated bot- 
 tom, then filters through the charcoal and is drawn off 
 by the pipe when it is needed. The advantage of this ar- 
 rangement is this: the suspended particles are caught most- 
 ly at the bottom of the filter and may become detached from 
 the filter, especially if water is forced through it from the 
 top in a downward direction at intervals. The filter can of 
 course be taken out at any time and the material aerated or 
 renewed. Many other materials have been used for filters 
 of small size — sponge, sand, cotton, flannel, earthenware, 
 common charcoal, etc. The small size filter acts simply as 
 a strainer in a short time, and requires frequent renewing, 
 otherwise it is worse than useless. Makers of all kinds of 
 filters, however, do not hesitate to aver that they are self- 
 cleansing, perfect, etc., etc., which, we have seen, is opposed 
 to the best and latest scientific research on the subject. Let 
 the householder be guided by the facts. 
 
 Where nothing better is at hand, water may be filtered 
 through a box perforated at the bottom, containing clean 
 quartz sand, resting on a plate of porous earthenware or on 
 bricks placed on top of the charcoal. Expose the filter to 
 the air from time to time. 
 
 Public Systems of Water Supply.— It will probably 
 not be long before our cities will demand purer water than 
 can be supplied by the wells and springs now used; many 
 of them being, without doubt, polluted by the many impu- 
 rities thrown on the surface. This involves a public system 
 of water supply, with its attendant system of reservoirs, fil- 
 ter beds, pipes, hydrants, etc. In view of such contingency, 
 it may not be out of place to mention some of the require- 
 ments that fluch a system should fulfill. 
 
46 SANITARY ENGINEERIXCi. 
 
 The water may be obtained from lakes, rivers and streams, 
 springs and wells, impounding reservoirs often being used 
 to collect that which falls on the hill-sides into one place. 
 
 This water may be conveyed for distribution (Rawlin- 
 son's Suggestions to Local Sanitary Boards, England, p 20,) — 
 
 " By means of open conduits (before filtration) ; 
 " " " covered* " (always after filtration) ; 
 " " " cast iron pipes under pressure. 
 
 A water supply may be gravitating, or the water may be 
 pumped by steam power. The relative economy of one or 
 the other form of works will depend on details of cost and 
 quality of water; as a rule, gravitating works require the 
 largest capital. The annual working expenses of a pump- 
 ing scheme may, however, be greatest. Reservoirs for ser- 
 vice distribution should be covered. 
 
 If filters are used, the water should not be exposed in 
 open reservoirs and tanks after filtration. 
 
 Cast iron pipes, properly varnished, should be used for 
 street mains. Lead should not be used with soft water, 
 either in service pipes or in cisterns. Wrought iron tubes 
 with screw joints may be used for home service. 
 
 Water at and below six degrees of hardness is considered 
 soft water ; above this range, water is termed " hard." 
 
 These " suggestions " of Mr. Rawlinson, (Chief Engineer- 
 ing Inspector to the local government board, London,) are 
 valuable, especially as they represent the best modern thought 
 on this subject, and may tend to prevent fatal mistakes in 
 designing water supply systems. 
 
 As he says, " The great modern improvement in water 
 supply is the delivery by constant service, and at high presswe, 
 over the entire area of a town, and into every bouse, cot- 
 tage and tenement, and should be secured where practi- 
 cable." 
 
 The "constant supply at high pressure" permits con- 
 
 ♦Covered, to prevent the growth of vegetable organisms. 
 
WATER SUPPLY. 47 
 
 sumers to draw water from the pipes at any time, and can 
 be made so efficacious in the extinction of fires as to dimin- 
 ish their destructive effects most materially. Fire engines 
 are not needed with such a system. It is said that in Paris, 
 owing to the excellent organization of the fire department, 
 that a destructive fire is almost unknown. The "intermit- 
 tent supply" does not offer these advantages. House cisterns 
 are required to stow the daily allowance of water, which is 
 only supplied at certain hours. The cisterns, if neglected, 
 may not be supplied with water, or they may leak, or absorb 
 foul gases, and finally suffer from want of cleanliness. 
 
 There is, besides the high pressure due to a sufficient ele- 
 vation of the reservoir above the town, the "Holly System" 
 of maintaining this high pressure in the pipes by steam 
 power. The pumping machinery is placed near the water, 
 which ispumped directly into the mains, the pressure being 
 kept constant, or increased or diminished at will. 
 
 This system is highly spoken of wherever it has been 
 tried. 
 
 Source of Supply. Available Rainfall. — In any one 
 of these systems, it is a first requisite that the source of sup- 
 ply shall be constant and unfailing. Where a large stream 
 is used as the source, the amount that can be depended on 
 in the dryest seasons may be estimated with some degree of 
 certainty. Where small lakes, springs, wells and small 
 streams are used as the source, we have to depend, more or 
 less, on the observed rainfalls for the different seasons, in 
 conjunction with the measured flow of the streams if any 
 to form, at best, only an approximate estimate of the yield. 
 
 Such observations should be conducted over a period of 
 twenty years if possible, to include all fluctuations ; but as 
 a rule, in this State, we have only a few years observations 
 of rain fall, and only one or two of the flow of streams to found 
 an estimate upon of the probable yield of water over a given 
 drainage area. 
 
 Let us suppose that an embankment is thrown across a 
 
48 SANITARY ENGINEERING. 
 
 Valley, to form a reservoir, into which shall be stored al 
 the water that drains into the valley from its "catchment 
 ground," whose area can be readily computed, as it is 
 bounded generally by well defined ridge lines and the em- 
 bankment in question. Now the yearly rain fall in diflFer- 
 ent portions of the State varies from 20 to 60 odd inches, 
 the average being high, over 45 inches certainly. If all 
 of this could be collected into reservoirs, the amount would 
 be given by simply multiplying the catchment area by the 
 depth of the rain fall ; thus, if the catchment area was one 
 square mile, 27,878,400 square feet, and the depth of rain 
 fall one foot, we should have 27,878,400 cubic feet in a year 
 or 76,379 cubic feet in one day for the supply. But in 
 practice we are very far from securing the whole rain fall, 
 the reason for which can be made plain by the following 
 considerations. 
 
 Let us first suppose the catchment ground to be imper- 
 meable and free from vegetation; then any rain that falls 
 all flows into the reservoir, except that lost by evaporation; 
 the latter being less as the surface is steeper, the tempera- 
 ture lower and the drainage area smaller. 
 
 If, however, the surface of the ground is 'perdous, as is 
 usual, then a portion of the rain fall sinks into the ground, 
 to appear again as springs, and thus drain ultimately into 
 the reservoir, or else to pass off by some subterranean 
 stratum to other outlets. In this case the amount lost by 
 evaporation is less as the ground is more absorbent and 
 better drained, the slopes steeper, and the temperature and 
 area smaller. If now we suppose the earth more or less 
 clothed with vegetation, the latter absorbs and partly evap- 
 orates still more water. The conditions of the problems are 
 thus seen to vary greatly for different localities, with the 
 season of the year, and it may be added, also with the winds 
 and relative humidity of the atmosphere. 
 
 In England, where observations have been conducted for 
 years over many distinct catchment basins, the loss due to 
 
WATER SUPPLY. 49 
 
 evaporation and absorption, has been found to range from 
 nine to nineteen inches per annum, and it is the prac- 
 tice to consider as available no more than the mean 
 fall for three consecutive dry years, (which is found to 
 be, as a rule, ^ less than the average rain fall,) after sub- 
 tracting the loss by evaporation. Thus, if the mean fall 
 for three consecutive dry years is about forty inches, 
 and if the loss by evaporation and absorption is put at 20 
 inches, this would leave 20 inches of rain fall that could be 
 utilized if it was all stored. 
 
 Observations on Lake Cochituate, Mass., water shed of 
 12,077 acres, from 1852 to 1 875, gave a yearly rain fall vary- 
 ing from 35 to 69 inches — average 50, and the percentage of 
 this received into the lake 25 to 74 — average about 45. It 
 is nevertheless recommended by some good engineers that 
 not over 12 to 15 inches of rain fall be counted on as avail- 
 ble in the United States, which is less than Humber allows. 
 
 The evaporation from the surface of the water in the 
 reservoir, in dry seasons, averages about ^ inch daily in 
 England, whilst it is as much as J inch in some localities 
 in India. The annual loss in England is put at 20 to 25 
 inches. It is, of course, much more in small and shallow 
 ponds, which can be more readily heated, than in extensive 
 reservoirs or lakes. Trautwine says that the daily loss from 
 evaporation in the three warmest months of the year will 
 rarely exceed ^ inch in any part of the United States. This 
 is probably too high, for the same authority found in the 
 tropics over a pond 8 feet deep, a loss of only 2 inches in 
 16 days, or | inch per day. The thermometer reached 115° 
 to 125° in the sun every day. It is evident from the fore- 
 going the importance of early making observations in each 
 locality for as long a period as possible, in order to ascer- 
 tain the ratio of the " available " to the " total " rainfall. 
 Raukine says that this ratio is about 1 for hard rocks, roof 
 surfaces, paved streets, &c., ^ to ^ for pastures, A to ^ for 
 fiat cultivated country, and for chalk. It follows that a 
 3 
 
50 SANITARY ENGINEEEIKG. 
 
 catchment basin is best located in the older formations, con- 
 sisting of hard rocks, whilst wells suit best the more previous 
 and recent deposits. London is even now preparing to give 
 up the Thames water altogetiier and to draw her supply 
 from her underlying chalk beds. 
 
 It is important to note that the most reliable method of 
 .ascertaining the available rainfall is to measure the actual 
 ■discharge of streams that drain a given water shed. Then 
 by comparison with the total rainfall on the water shed, we 
 find the actual amount lost by evaporation and absorption 
 ■of the ground. 
 
 No town which contemplates a public water supply 
 should neglect to have such observations made, covering a 
 period as long as possible, to take proper account of 
 droughts, &c. 
 
 Consumption per Head. — Statistics show that in Eng- 
 land the daily amount of water used in the towns and cities 
 varies from 15 to 50 gallons per head — 30 being regarded as a 
 full allowance. In the United States the daily consumption 
 per head varies from 25 to 120 U. S. liquid gallons of 231 
 ■cubic inches (1 cubic foot — 7.48052 gallons) ; and it is rec- 
 ■ommended by some to allow 40 to 50 gallons per head for 
 smaller cities, and an increasing amount as the population 
 increases. 
 
 It is very plain, from the records, that an enormous w.aste 
 occurs in our cities, and special attention is now being -di- 
 rected to it. Where inspections, or water meters have been 
 tried, the amount consumed has often been reduced to half 
 and even one-third the original amount. Humber estimates 
 that 20 to 25 gallons is a liberal allowance. Even if we 
 assume double this, it still behooves us to take every pre- 
 caution to avoid waste by the use of meters or otherwise ; 
 else the large yearly cost of the water supply may be need- 
 lessly doubled or trebled. 
 
 Reservoir Capacity. — Well, assuming, say 45 gallons 
 .the daily demand on & reservoir is made up of the 45 gallons 
 
WATER SUPPLY. 
 
 51 
 
 X number of population, plus the daily evaporation from 
 the surface of the water, plus any compensation water to 
 mill owners or others. Subtracting from this the dry 
 weather flow of the streams discharging into the reservoir, 
 we get " the excess of the demand over the supply " in dry 
 months; and this multiplied by the number of days storage 
 of the reservoir, gives its available capacity^ or the volume it 
 must contain between its highest and lowest working levels. 
 Some advise that every storage reserVbir should, if possible, 
 contain six months of the excess of the daily demand above 
 the daily supply for the dryest consecutive six months. 
 Some English engineers formulate the following rule, as the 
 result of considerable experience; "The number of days 
 storage of reservoir" equals the number 1,000 divided by 
 the square root of the rainfall in inches for three consecutive 
 dry years. Thus, if this rainfall is 36 inches, the reservoir 
 should contain 1,000 ^ 6 = 166.7 days storage ; that is, 166.7 
 times the excess of the demand over the dry weather supply. 
 The following table (see " Engineering News," Aug. 23, 
 1879,) will show the great disparity between the l^ast and 
 greatest flow of streams : 
 
 
 Drainage Area 
 Square miles. 
 
 FLOW IN CUB FT. PER SQ. MILE. 
 
 Name of River. 
 
 Greatest Flow. 
 
 Least Flow. 
 
 
 10,234 
 
 4,136 
 
 1,800 
 
 1,100 
 
 981 
 
 339 
 
 352 
 
 84 
 
 76 
 
 20 
 
 20.27 
 23.40 
 
 30.23 
 20.33 
 
 74.87 
 12.64 
 
 41.60 
 54.43 
 
 51 
 
 
 53 
 
 Schuvlkill 
 
 0.21 
 23 
 
 Tyne, England, 
 
 Pi<ssaic, 
 
 Croton, 
 
 15 
 
 Concord, 
 
 0.17 
 
 H^'CkensEck, . .., 
 
 33 
 
 Sudbury, 
 
 05 
 
 Croton, W Branch,.. 
 
 o!o2 
 
 " These figures show that on large drainage areas the pro- 
 portional flow is less in freshets and greater in dry seasons 
 than on small areas." 
 
52 SANITARY ENGINEERING. 
 
 The " least flow " given above is probably the least How 
 on any day of the dry season. If, however, our reservoir is 
 to contain, say 6 months supply, then we desire to know the 
 least average flow for any 6 months during 20 or more years. 
 Suppose this to be 0.2 cubic feet per second per square mile 
 of drainage area, or 17,280 cubic feet per day per square mile. 
 
 Suppose a population of 10,000 consuming daily 6 cubic 
 feet (45 gallons, say) per head, or 60,000 cubic feet in all ; 
 and that the loss by evaporation from the reservoir of 10 
 acres say, is ^ inch daily, or about 5,000 cubic feet. The 
 total daily demand is thus 65,000 cubic feet, which is about 
 48,000 cubic in excess of the supply from the stream j so 
 that if the reservoir is to contain 6 months=180 days of this 
 excess, its available capacity must be 48,000x180=8,640,000 
 cubic feet, or an average available depth over the 10 acres of 
 20 feet, 
 
 It is evident that if the daily demand, as above, is 65,000 
 cubic feet, the yearly demand thus being 23,725,000 cubic 
 feet, that but little over 10 inches of rainfall over the 1 
 square mile of drainage area has been secured, since 10 
 inches on a square mile gives only 23,232,000 cubic feet. 
 This is certainly within reasonable bounds. 
 
 No allowance is made above for compensation to mill- 
 owners. 
 
 Of course, by building the reservoir of sufiBcient capacity 
 the whole of the rainfall, minus the loss bj' absorption, evap- 
 oration and leakage, can be utilized ; but it has not been 
 found desirable to build such huge reservoirs in actual prac- 
 tice, so that much of the rainfall is purposely allowed to run 
 off. 
 
 Sources of Water Supply in TS.C.', Maintenance of 
 Purity. — This State is abundantly supplied with unfailing 
 sources of water supply in her many rivers and lakes, not 
 to speak of the underground water, which hitherto has been 
 the only source used in the supply of her largest towns. 
 What a contrast do the rivers and streams of England — 
 
WATER SUPPLY. 58 
 
 many of them fouled to inky blackness by the refuse of 
 thousands of manufactories — present to our own waters, 
 teeming with fish and drinkable almost everywhere. It is 
 to be hoped that the enacting of wise laws will maintain 
 their purity, by forbidding any injurious waste or crude 
 sewage from entering them. If this system is inaugurated 
 from the beginning, much trouble may be avoided. Eng- 
 land now is making a brave effort to regain the pristine pu- 
 rity of her streams ; let us be careful not to lose this thing of 
 beauty in our own waters. 
 
 The foregoing notes are very brief, but they may contain 
 some useful hints to our larger towns and cities, who will 
 sooner or later abolish the polluted well and adopt a public 
 system of water supply. 
 
54 SANITARY ENGINEERING. 
 
 V 
 
 CHAPTER IV. 
 
 WATER SEWERAGE- 
 
 Then will likely follow the complex system of water sewer- 
 age, which is now regarded as the best for the largest cities ; 
 though it is admitted that it is a delicate machinery and 
 requires the greatest care in its manipulation. 
 
 This system has been so thoroughly studied that a suffi- 
 cient literature exists on the subject to answer the needs of 
 practice ; so that it is needless to enter into any very tech- 
 nical discussion of it here. 
 
 Conditions that the system. should fulfill. — The object 
 to be accomplished by tiie system is to carry all offensive 
 matters underground, and as rapidly as possible, out of the 
 city, by the aid of the water used in the houses and the rain 
 water that falls. The proper carrying out of a system of 
 this kind requires the aid of enlightened sanitary engineers 
 of experience ; above all, in the general design. Jenkin's 
 " Healthy Houses," already referred to, is suflScient to show 
 the general reader, not only the cause of many failures, but 
 the remedy ; in fact some of the conditions that the system 
 should fulfill. Let it be borne in mind by any town con- 
 templating the water system, that an error in design, like 
 the bad foundation to a structure, is often very difficult to 
 remedy. 
 
 Special emphasis is laid on the principle, that the sewage 
 should be carried out of the town limits quickly — say in 24 
 hours, or less, when practicable. This is effected by a cor- 
 rect adjustment of the size and shape of the sewer to its fall, 
 having assumed the total amount of sewage that is to be 
 provided for daily. The question is one of hydraulics, and 
 may be solved by the use of well known formulae for the 
 flow of water in channels. 
 
"WATBR SEWERAGE. 55 
 
 Example. — As an illustratioti, take the following, from 
 " Rawlinsou's Suggestions ": " The sewage of a town or vil- 
 lage will consist of waste water and excreta from the houses, 
 and the volume, in round figures, may range from 100 to 
 250 gallons per day from each house. This volume will 
 probably flow off in about eight hours, so that tiie sewers 
 must provide fur not less than three times this volume, if 
 even every drop of roof and surface water can be excluded. 
 As this cannotin all cases be accomplished, the sewers should 
 provide for not less than 1,000 gallons from each house ; or 
 for a town of 1,000 houses (5,500 population) have a deliver- 
 ing capacity of about 1,000,000 gallons (daily). An outlet 
 sewer of 2 feet diameter, laid with a fall of 5 feet per mile, 
 will deliver upwards of 2,000,000 gallons, flowing a little 
 more than half full. Lesser diameters will .answer where 
 there are greater falls." 
 
 A 2 feet sewer thus provides for doubling the population 
 in a few years. 
 
 Now 100 to 250 gallons per day, from each house, con- 
 taining 5J persons, corresponds to from 18.2 to 45.5 gallons 
 per day for each person, which figures represent about the 
 extremes in English practice ; 30 gallons being the usual 
 allowance, excluding rain water. 
 
 In the case above, the velocity of the sewage of 11,000 per- 
 sons is about 2 feet per second, which is the minimum vel- 
 ocity in order thai so small a sewer may be self -cleansing. 
 
 As the velocity is less for the real population of 5,500, 
 especially if they use less water than 1,000,000 gallons, the 
 inclination of the sewer should be increased if possible, or 
 "flushing" will have to be resorted to, or the sewer must be 
 made smaller than the 2 feet diameter, to secure the proper 
 velocity to make the sewer self cleansing, and to prevent the 
 formation of the poisonous sewer gases, which are always 
 formed when the progress of the sewage out of the town is 
 slow, in spite of all the ventilation schemes that may be 
 tried- 
 
56 SANITARY ENGINEERING. 
 
 A circular sewer, one foot in diameter, running half full, 
 at an inclination of 1 to 600 will discharge 46.3 cubic feet 
 per minute, at a velocity of 118 feet per minute, equivalent 
 to a discharge of 167,000 gallons (in round numbers) in 8 
 hours. This is slightly over the discharge of 5,500 persons, 
 allowing 30 gallons to each person, so that this one foot 
 sewer would suffice if rain water is to be disregarded. 
 
 Amount of Rain Fall to Pass into Sewers. — ^Let us 
 next ascertain the size of a sewer on the supposition that 
 the town is one square mile in area, and that a rain fall of 
 one inch in 24 hours actually drains into it. The rain fall 
 is 2,323,200 cubic feel in 24 hours ; or at the rate 
 of 1,613 cubic feet in one minute. By use of proper formu- 
 lae, it is found that an egg shaped sewer, 3J by 5 feet, run- 
 ning full, will discharge the water at a velocity of 3| feet 
 per second, the inclination being taken, as at first, at only 
 5 feet to the mile. 
 
 We can now readily see, by this particular example, how 
 much the size, and hence the cost, of sewers is increased by 
 making provision to receive the rain fall. It is, of course, 
 far more expensive to provide for the exceptionally heavy 
 rain falls (as " 6 inches in 2 hours," etc.,) which sometimes 
 occur. Sewerage systems in this country do not provide for 
 such exceptional rain falls. 
 
 The London sewers were constructed to carry J inch rain 
 fall in 24 hours, at the time of maximum flow of sewage, 
 larger amounts being provided forby storm water overflows. 
 
 It is found that diflferent soils, or surfaces, have not the 
 same absorptive power; thus in London the sewers in some 
 sections deliver one-half the rain fall, whilst in entirely 
 paved streets, nearly the whole of the water is drained into 
 them. 
 
 Latham says that in Croyden, the soil being porous, 
 gravel overlying chalk, "the amount of rain contributed by 
 a storm of .72 inch in 12 hours, did not yield more than 
 one-tenth of it to the sewers." More impervious districts 
 required the full allowance of 1 inch in 24 hours, together 
 
WATER SEWERAGE, 57 
 
 with the sewage. In Dantzic, which is sandy and flat, J* 
 inch in 24 hours, together with 2 cubic feet of sewage in 8 
 hours was assumed as the basis for computations. 
 
 It is plain from what precedes, that any town contempla- 
 ting a sewerage system, should be able to form some judg- 
 ment as to the amount of rain water to be admitted to the 
 sewers, if any at all. 
 
 Argument for and against excluding rain water 
 from sewers. — The reasons for and against separation of 
 the rain water may be stated as follows : 
 
 For Sqtaration. — It is urged that even if a distinct set of 
 sewers is used to convey away the rain water, that it is 
 cheaper; since the rain water sewers can discharge into the 
 nearest stream (thus giving it its natural volume) and can 
 thus be made shorter than the sewage conduit, which is 
 often carried a considerable distance ; besides the sewage 
 conduit is very much smaller and therefore cheaper in this 
 case. Again, on account of the small size of the conduit, 
 the sewage is carried out of town much more quickly ; thus 
 preventing that stagnation which sometimes occurs in large 
 sewers, having only a thin film of sewage flowing slowly 
 over the bottom, much of the solid material being deposited 
 to decompose and generate the most hurtful gases. 
 
 Likewise, the manurial value of the sewage is increased 
 and any expense of pumping very much diminished. 
 
 Against Separation. — It is urged on the other side, that 
 chemical analysis shows that, in large cities, the storm wa- 
 ters wash away so much filth as to render the water as im- 
 pure as the sewage; so that, at least, the first portions of 
 the rain fall should be admitted into the sewage conduits, 
 though the balance may be passed into the streams. Also 
 there are objections to the use of so many pipes in the streets; 
 two sets of sewage pipes, with smaller drains often crossing, 
 besides gas and water pipes ; the drainage pipes too having 
 to be laid evertwhere with a fall. It is plain, however, that 
 if the surplus of the rain water is to be allowed to go where 
 
58 SANITARY ENGINEERING. 
 
 it can, that the old channels should at least be so much im- 
 proved as to prevent flooding of cellars and formation of 
 any stagnant pools anywhere. So much separate drainage 
 should at least be insisted on. 
 
 It is certainly in the line of simplicity to adopt but one 
 set of sewers; and experience shows that in most towns it 
 rarely causes any inconvenience from flooding. 
 
 If drainage pipes have already been laid, they should not 
 be abolished, even if sewers are afterwards projected. 
 
 Subsoil Drainage. — If there is but one sewer system, 
 then the subsoil must be drained by small pipes, simply 
 butted together at the ends, so that the subsoil water can 
 enter. The pipes must be placed on top of the sewer pipe to 
 prevent any infiltration from the sewer, which often hap- 
 pens if they are placed below the sewer. This subsoil drain- 
 age is especially necessary in a retentive soil, to render the 
 soil porous, so that it can more effectually do its work of 
 oxidation on any gases that may pass through the sewer. 
 
 The latter should be rendered as impervious as possible, 
 for leakage through bad sewers into the ground soon satu- 
 rates it with the vilest poison, that invariably produces harm 
 as soon as it can find an outlet to tlie outer air. 
 
 Form, Inclination and Ventilation of Sewers. — Small 
 circular sewers can be made of earthenware pipe, larger ones 
 of brick in cement or of concrete, and egg shaped, to give a 
 greater velocity to a small flow. Main sewers should not be 
 laid at greater inclinations than cause a velocity of six feet 
 per second, if possible, to avoid the cutting out of the bot- 
 tom of the sewer by grit and other solids. The location of 
 the main outlet sewer determines, to a great extent, the po- 
 sitions of the other sewers, and should receive special study. 
 House drains should be trapped and ventilated between the 
 house and sewer. The main sewers should be ventilated by 
 direct communication with the external air, at least every 
 100 yards. This prevents that partial and noxious decom- 
 position which occurs in close places having a limited 
 
WATER SEWERAGE. 59 
 
 amount of air. " In fully ventilated sewers the sewer air is 
 purer than that of some stables, or even in a crowded public 
 room." 
 
 Nothing is so much insisted on in the best modern prac- 
 tice as thorough and complete ventilation of all sewers and 
 house drains and pipes. 
 
 House Pipes. — Above all, in this water system, the house 
 connections require the greatest care in their construction 
 and design to keep the lurking poison out of the house ; and 
 it is regretted that want of proper diagrams necessitates the 
 ignoring of this branch of the water system in this paper. 
 
 Disposition of Sewage. — Having briefly considered some 
 points of general interest in connection with the design of 
 sewerage works, let us next enquire what is to be done with 
 the sewage. 
 
 The plan most in vogue in this country is to discharge 
 the sewage matter into some stream, which may thus be 
 regarded, in one sense, as the continuation of the sewer. 
 
 In the case of tidal waters, however, if the refuse is emptied 
 near the city it floats up and down the city past it, giving 
 anything but an air of cleanliness to the eye, or of satisfac- 
 tion to the nose. 
 
 In England, the law now "requires that rivers and 
 streams are not to be polluted by the admission of crude 
 sewage, even from existing sewers." 
 
 Rawlinson states that up to October, 1878, " there are 
 about 87 towns, districts,- parishes, and places whose sewage 
 is disposed of by irrigation. There are 23 towns, &c., whose 
 sewage is disposed of by precipitation, treatment with chemi- 
 cals, and partial land-filtration. There are 24 towns, &c., 
 whose sewage is disposed of by ruder and more imperfect 
 modes of filtration, as through charcoal, wicker work and 
 straw. There are 16 towns, &c., whose sewage is disposed 
 of by mechanical subsidence only." The sewage is first car- 
 ried by the outlet sewer to the " sewer farm," where, if nee- 
 
60 SANITARY ENGINEERING. 
 
 essary, it is pumped into large tanks, to be then treated 
 according to some of the methods given above. 
 
 Irrigation and Filtration.— The best method probably 
 is irrigation, or fMration through a porous soil. 
 
 This plan might be carried out by passing the sewage at 
 intervals from large tanks, where it is collected, through 
 hundreds of earthenware pipes, loosely jointed, placed about 
 one foot below the surface of the ground and in parallel 
 rows. The sewage leaks through the joints into the sur- 
 rounding soil, which purifies it by absorption and oxidation- 
 A better known method consists in-simply passing the fluid 
 sewage on to ground, deeply drained. The purified water 
 runs off in the drains. 
 
 By distributing the sewage over a sufficient extent of sur- 
 face, it is found that the soil does its work perfectly; being 
 aided, moreover, by the growing vegetation, taking up much 
 of the sewage through its roots. The purification, though, 
 is principally due to the earth, which has the property of 
 absorbing and condensing gases, such as air, &o.; so that 
 each little particle of earth is surrounded with condensed 
 oxygen, which acts upon the sewage matter the instant it 
 comes in contact with it, and oxidizes the organic part,— ^ 
 throwing off some of it into the air — not as poisonous efflu- 
 via, which is the result of decomposition with a limited 
 amount of oxygen, as in close drains, but as harmless 
 aqueous vapor, carbonic acid and ammonia. The amount 
 of oxygen absorbed by the soil is not large, but it seems to 
 be replaced as rapidly as it enters into combination, and 
 thus to furnish an indefinite supply to the matter with which 
 it combines. (See Johnson's "How Crops Feed," pp. 218 
 168, etc.) 
 
 It must then be distinctly understood that the putrescent 
 substances are not simply absorbed (as usually stated) by the 
 earth or charcoal, or other porous material ; but are chemi- 
 cally changed — oxidized or burnt up — so that their objec- 
 tionable features are no longer perceived ; the nitrogen, etc., 
 
WATER 8EWEEAGE. 61 
 
 is thrown ofFiuto the air, or passes off in the water as nitrates, 
 or nitrites, so that the earth ultimately has about the same 
 constitution after its use in the manner indicated as before. 
 
 At Merthyr the effluent water from the filter beds was 
 analyzed by Dr. Frankland, showing that when 230, 500 
 and 1,200 people were draining on to them per acre, the 
 effluent water was respectively 30, 16 and 3 or 4 times purer 
 than the standard of fair potable water, so far as chemical 
 analysis is taken as the criterion. 
 
 It is thus seen how effectually surface soil, where there is 
 plenty of air, does its work. It is warmly advocated by 
 Geo. E. Waring, Jr., (see "The Sanitary Condition of Dwell- 
 ing Houses," Van Nostrand,) to get rid of all liquid refuse, 
 about the country or town house, where there is no system 
 of sewers, by passing it through loosely jointed pipes, laid 
 about one foot below the surface in the back yard. He 
 states that the system has been found to work admirably, 
 winter and summer wherever tried. 
 
 It may be stated that the efforts that have hitherto been 
 made to utilize the fertilizing properties of sewage have not 
 been profitable, unless in the way of irrigation. Fine crops 
 have been raised on such sewage farms; so that where in- 
 termittent filtration is adopted, it is advisable to combine 
 sewage farming with it to lessen the expense. 
 
 The Chemical Processes used so far have not been 
 found to purify the sewage thoroughly by themselves, so 
 that natural or artificial filtration must supplement any 
 chemical treatment. Besides this objection to the chemical 
 method, its cost and difficulty of manipulating the accumu- 
 lations of sewage sludge both make against it; still much 
 of this sludge must be removed in some way before filtra- 
 tion can be employed. 
 
 In seaboard towns, the natural outfall for the sewage is the 
 sea. If possible the sewage should be carried to such a dis- 
 tance as not to be brought back to the town by wind, tides 
 
62 SANITARY ENGINEERING. 
 
 or current. The same remarks apply to towns situated on 
 tidal streams and estuaries. 
 
 Caution to our Cities. — Most of our large towns have a 
 clean slate for sewerage systems. Let not a single sewer be 
 built until a competent engineer plans the entire system, 
 otherwise the sewers may have to be torn up eventually, or 
 the engineer may be considerably embarrassed inhis designs. 
 The Secretary of the Board of Health, Dr. Wood, writes of 
 Wilmington, that " there is an incipient sewer system here 
 which promises to be a great nuisance, from the beginning 
 they have made with it." It seems a pity for Wilmington 
 to make a botch of it the very first move. 
 
 THE LIEENUR SYSTEM. 
 
 In a paper read before the Austrian Society of Engineers, 
 Vienna, (see Baldwin Latham's "Sanitary Engineering," 
 Am. ed.) Mr. J. Chailly says : 
 
 "The two conditions of removal without producing disa- 
 greeable odors, and carrying off the matter in short periods, 
 are almost entirely fulfilled in Lieurnur's Pneumatic Sewer- 
 age system, in which the iron waste-pipes, which are water- 
 tight and air-tight, are united to a system of iron pipes 
 which run into a central station, where the air-pump is 
 placed which pumps all the matter into a reservoir. The 
 collection and sale of this matter does not usually cover the 
 cost of the labor. The reports on this system are conflict- 
 ing, and yet the majority of them speak in its favor." 
 
 Mr. C. Norman Bazalgette, in a late paper to the London 
 Institution of Civil Engineer, says of this system from the 
 experience gained at Leyden, Amsterdam and Dodrecht, 
 that " it was supplementary to, and not substitutive of, a 
 water carriage system, extremely costly, and its mechanism 
 was extremely complicated and liable to get out of order. 
 The accumulation of sewage residium in the central reser- 
 voir, and its subsequent decanting into barrels, were opera- 
 
WATER SEWERAGE. 63 
 
 tions which could not fail to be objectionable and offensive. 
 In conclusion, the system — though it might have a partial 
 province in the tide-locked cities of the Hague, where no 
 system of sewerage was available — should never be import- 
 ed into an English town." 
 
 It would seem that there would be considerable difficulty 
 experienced in the case of repairs to the pipes being needed. 
 
 THE ROCHEDA'LE PAIL SYSTEM.* 
 
 This consists simply in half-barrels or pails being placed 
 under the seats of the closed privy to receive the fecal dis- 
 charges ; the pails being removed about once a week, after 
 putting on a hermetically tight cover, empty disinfected 
 pails taking their place. The matter is carried out of the 
 town at night, and may be spread on old fields, a slight cov- 
 ering of drj' earth being used to keep down the smell, or 
 the matter may fee sold for manure. It is well to add dry 
 earth, ashes or charcoal every day, to the pails in use, and 
 moreover to ventilate the privy. 
 
 This system is an excellent one for most of our towns and 
 small cities. Having to carry the pails through the house 
 or yard to the street is an objection. It is now being tried 
 on a large scale in New Orleans, where the water system 
 cannot be readily used. 
 
 All of our cities and towns can introduce this system with 
 such a small outlaj'- of capital, that it would seem to be the 
 one just now to be most highly recommended. 
 
 The corporation should bear the expenses of the transpor- 
 tation of the excrementitious matter, as well as of other re- 
 fuse and filth found in all towns, due to various causes. 
 
 *See Appendix 11, page 79. 
 
64 SANITARY ENGINEERING. 
 
 THE DRY EARTH SYSTEM. 
 
 The great advantages offered by the "dry earth closet" is 
 well known, and its admirable adaptability to the sick room. 
 
 The system proposed is founded on this, and consists in 
 the same pails used in the preceding system, placed in closed 
 privies, on firm and dry plank or concrete foundation* The 
 only difference is, that in this system greater care is used in 
 spreading charcoal or dry earth over the night soil, so as to 
 burn it up as quickly as possible, and that the pails are 
 emptied in a tight vault on the premises, a little earth being 
 thrown on top of the emptied mass, to keep down odor and 
 continue the work of exodation to completion. 
 
 There appeared an excellent article on " Village Sanitary 
 Work " in Scribner's for June, 1877, by George E. Waring, 
 Jr. The writer says : " In the autumn of 1876, I had 
 brought to my house, where only earth closets are used, two 
 small cart loads of garden earth, dried and sifted. This was 
 used repeatedly in the closets, and when an increased quan- 
 tity was required, additions were made of sifted anthracite 
 ashes. The amount of material now on hand is about two 
 tons, which is ample to furnish a supply of dry and decom- 
 posed material whenever it becomes necessary to fill the 
 reservoirs of the closets. The accumulation under the seats 
 is discharged through valves into brick vaults in the cellar. 
 When these vaults become filled — about three times in a 
 year^ — their contents, which are all thoroughly decomposed, 
 are piled up in a dry and ventilated place, with a slight 
 covering of fresh earth to keep down any odor that might 
 arise. After a sufficient interval these heaps are ready for 
 further use, there being no trace in any portion of foreign 
 matter or any appearance or odor differing from that of an 
 unused mixture of earth and ashes. In this way the material 
 
 See Appendix n, pages 77, and 78. 
 
WATER SEWERAGE. 65 
 
 has been used over and over again, at least ten times, and 
 there is no indication to the sense of any change in its con- 
 dition." 
 
 The same earth can be used over and over again, thu& 
 doing away with what was once urged as the principle ob- 
 jection to the earth closet system — the continual removal of 
 large bodies of earth. 
 
 A chemical analysis showed that there was no more or- 
 ganic matter in the used earth than in fresh earth, thus 
 proving that in this case 800 pounds of nitrogen, etc., had 
 gone back to the air in a harmless state, the solid organic 
 matter being estimated at 800 pounds, of which some 230 
 was nitrogen. 
 
 The powerful disinfecting properties of charcoal are welL 
 known. When there is odor about a dead body, there is 
 nothing better than carbon in some of its forms to destroy it. 
 The smoke from burning tar, coffee, dried apples, etc., hav& 
 all been successfully tried. 
 
 A covering of charcoal will preserve tainted flesh of any 
 kind ; the dog instinctively acts upon this principle when 
 he buries a bone in the earth to make a repast upon some 
 days or weeks afterwards. In all these cases it is not the- 
 charcoal or earth, but the oxygen contained in its pores that 
 destroys the odors and burns up the substance. 
 
 As Mr. Waring says, " earth is not to be regarded as a 
 vehicle for the inoffensive removal beyond the limits of the 
 town of what has hitherto been its most troublesome pro- 
 duct, but as a medium for bringing together the offensive 
 ingredients of this product and the world's great scavenger,, 
 oxygen. This oxygen does its work of liberating the or- 
 ganic elements so well that, according to Professor Voelcker,. 
 "the use of the same earth four or five times over, although 
 perfectly successful in accomplishing the chief purpose of 
 deodorization, fails to add to it a sufiicient amount of fer- 
 tilizing matter to make it an available commercial manure," 
 
66 SANITARY ENGINEERING. 
 
 This agrees with the analysis previously mentioned. If 
 the earth does its work thoroughly, the manure is lost, for, 
 in truth, this is the object to be accomplished; to drive the or- 
 ,ganie elements back again, uncombined, or at least in harm- 
 less combinations, to the air ; and this the condensed oxygen 
 accomplishes. 
 
 One advantage of the system is that the privy or " com- 
 mode," may be attached to the house ; in fact the best earth 
 ■closets may be kept in the chamber, without any other odor 
 ibeing perceived than that of the eartli used, which should 
 be_^ne, dry and sifted. 
 
 This dry earth system is familiar to soldiers of the laie 
 ■war, the sinks used by them receiving daij}'^ a slight cover- 
 ing of the very earth thrown out in their construction. 
 This effectually prevented deleterious effects ; and in exact 
 accordance with the theory and facts previously adduced, 
 the organic matter was so soon dissipated — when the sys- 
 tem was carried out faithfully — that the earth was not worth 
 removal as manure. This fact I know from experience; 
 and it agrees with all other experiments and analyses refer- 
 ring to this point.. When the earth covering is too slight, 
 ■or it is neglected at times, the result will be more manure 
 but diminished healthfulness. There can be no hesitation 
 in the choice. 
 
 Where the dwelling place contains a garden., the used earth 
 ■may be put on it, for it is quite probable that even when 
 most, or all of the organic matter, has been driven off, that 
 the chemical changes effected may have libsra'ed potash or 
 ^soda, etc., in the original soil, thus renilering it more valua- 
 ble than before to plants. 
 
 It may be interesting to know that there is biblical sanc- 
 tion for this method; the Israelites being required to carry 
 out the system whenever they went outside of the camp to 
 ease themselves. (Deut., xxiii : 13.) 
 
 It is admitted that this system d(.es not admit of the same 
 public control as the preceding ; but it may be made emi- 
 
WATER SEWERAGE. 67 
 
 nently serviceable by those who desire it. It is especially 
 applicable to country houses and the smaller villages. 
 
 I know of this system being carried out and satisfying 
 the daily wants of from 70 to 100 persons — the room being 
 almost entirely free from odor at all times. If sulphate 
 of lime is added, it fixes the ammonia that would otherwise 
 be driven off, and thus renders the product of sonie use as 
 a fertilizer. 
 
 When epidemics prevail, then in addition to usual meth- 
 ods of sewage disposal, disinfectants should be used, as to 
 which see another paper issued by the Board of Health on 
 the subject. 
 
 CONCLUSIONS. 
 
 In taking a retrospective glance at what has preceded, we 
 cannot but be impressed with the beneficence of those law^s 
 that tend, in one eternal roun<J, to the purification of what 
 man has made unclean. Foul sewage is thrown into a crys- 
 tal stream, whose hitherto transparent waters now blush at 
 the pollution. She invokes the aid of the ever constant 
 winds and of tlie animal and vegetable life she bears in her 
 bosom. They respond, and, in time, she is once more pure 
 and undefiled. The pure water falls from clouds, cleanses 
 our soil and passes into the earth, Joul, to again issue in 
 wells or springs, generally free from the taint of man^s 
 works. 
 
 Mother earth condenses gases that oxidize and liberate 
 noxious, waste elements in harmless combinations. We 
 breathe into the air a hurtful gas; but the winds and the 
 rains bear it from us, or the vegetation reaches out its leaves, 
 with their million little mouths, to absorb it and give us in 
 exchange the life giving oxygen. 
 
 Is it asking too much, should Nature call sometimes for 
 man's assistance to expedite results, in order that he may 
 add to his days and happiness ? If not, then ponder well 
 
68 SANITARY ENGINEEKING. 
 
 on the means that have been proposed to assist nature in 
 her work of purification, and act on them. 
 
 It is not intended that the foregoing brief summary of 
 "means" is complete. It was not intended to be, though 
 fundamental general principles, proper to be known at 
 present, it is hoped have been stated clearly and fairly. 
 
 Burton says that most men make books like apothecaries 
 make medicine, by pouring from one bottle into another. 
 This one belongs to that class — successful experience has 
 been inculcated rather than novel theories. The solutions 
 used have been standard ones — often huge bottles have been 
 poured from, even the crude materials of the still have been 
 obtained and digested before using. Most of the elixirs 
 mixed beautifully, forming clear solutions ; others did not, 
 and had to be specially treated to remove the antagonistic 
 elements, whilst others as my " germ " bottle would not 
 pour at all scarcely, the fluid being dark and viscid. 
 
 The object of such papers as this is to advise the public, 
 who cannot be thinking all the time about sanitary matters, 
 with regard to efficient means of protection against sickness, 
 and especially against epidemics. The county boards of 
 health are looked to as the authorized agents in introducing 
 more effective sanitary measures. But it is well known that 
 such organizations cannot go far ahead of public opinion. 
 We need the aid of the press, the great educators of public 
 opinion, to assist in the good fight for health. 
 
 Let srme of the systems for the disposal of sewage matters 
 be faithfully carried out simultaneously with a proper at- 
 tention to ventilation, drainage, water supply, and the gene- 
 ral cleanliness of streets and yards, and it is believed that 
 the death rate will be lowered and that epidemics will be 
 almost unknown. 
 
 Let every open privy and cess-pool be abolished with their 
 pestilential odors ; it follows that the source of contamina- 
 tion of the wells will be gone, and that zymotic diseases will 
 have their usual channels of attack effectually cut ofL 
 
WATER SEWERAGE. 
 
 69 
 
 Let us, then, advance towards that higher civilization 
 which demands pure air and wholesome water, not simply 
 as a luxury to be enjoyed only on the cool mountain's sides, 
 but as a necessity, to be enforced in city and village by strin- 
 gent laws and requirements. 
 
APPENDIX I. 
 
 The following table may prove a convenience to those 
 who use cisterns. It gives the capacity of a cylindrical cis' 
 tern, for one foot in height, and the diameters given, in U, 
 S. liquid gallons (of 231 cubic inches each), the nearest 
 whole number being taken: 
 
 Diameter. 
 
 Capacity. 
 
 Diameter. 
 
 Capacity. 
 
 Feet. 
 
 Grallons. 
 
 Feet. 
 
 Gallons. 
 
 5 
 
 147 
 
 15 
 
 1322 
 
 6 
 
 211 
 
 16 
 
 1504 
 
 7 
 
 288 
 
 17 
 
 1698 
 
 8 
 
 376 
 
 18 
 
 1903 
 
 9 
 
 476 
 
 19 
 
 2121 
 
 10 
 
 587 
 
 20 
 
 2350 
 
 H 
 
 711 
 
 21 
 
 2591 
 
 12 
 
 846 
 
 22 
 
 2843 
 
 13 
 
 993 
 
 23 
 
 3108 
 
 14 
 
 1151 
 
 24 
 
 3384 
 
 Multiply these tabular numbers by the height of the cis- 
 tern in feet to get the capacity of a cistern corresponding to 
 that height. 
 
APPENDIX 11. 
 
 Through the courtesy of Dr. Charles F. Folsom, of the 
 Massachusetts Board of Health, the accompanying wood 
 cuts are presented — they having first appeared in the Mas- 
 sachusetts Report of the Board of Health for 1876. 
 
 The cuts represent in order the natural drainage from 
 open privies and sinks, into wells that are placed too near 
 them ; sections of common privies and sink hole, both pol- 
 luting'the soil around them ; and lastly, three plans for pri- 
 vies based upon the dry earth system. 
 
 It is to be observed with respect to the latter, that the 
 conditions are simply that the pails used be completely un- 
 der cover and placed upon a dry foundation, so that no 
 matter from the pails shall ever reach the ground below 
 them, thereby poisoning the air with its efHuvia and the 
 wells with its drainage. 
 
 It is necessary that.the earth, charcoal or ashes be kept in 
 a dry place and under cover, the most convenient place be- 
 ing an apartment just to the rear of the pails, from which 
 it can be readily shovelled into the pails under and not 
 through the seats as when the ashes etc., are kept in the privy 
 room proper. 
 
 An ordinary open privy can generally be transformed into 
 one closed from the access of rain, by cutting out a space in 
 the weather-boarding of the back, njarlyas high as the top 
 of the seats, and replacing this boarding by a door working 
 on vertical or horizontal hinges, as shown in one of the fig- 
 ures. On opening this door, the half barrels or pails can be 
 set under the seats, and every morning charcoal, etc., can 
 be thrown over the contents so as to keep down all odor. 
 The pails should be set upon a plank or stone foundation — 
 at least upon a few blocks or bricks — to elevate them a few 
 
74 APPENDIX II. 
 
 inches above the ground, so that water may not reach therri. 
 As the pails are filled they should be emptied under a shed 
 and dry earth, etc., strewn over the contents, the action of 
 which in destroying the organic matter has been already 
 explained. 
 
 Where wells are at a distance, the contents of the pails 
 might be emptied on cultivated ground for their manure, 
 a slight covering of earth being again used to keep down 
 any odor that might arise 
 
APPENDIX II. 
 
 75 
 
 Qfcd'rti 
 
 ^Fi 
 
76 
 
 APPENDIX II. 
 
 \asnoi{f3 apiff 
 
 '.a 
 
 -.0 
 
 
APPENDIX II. 
 
 77 
 
 Jifanchesier Corpotcdion.. 
 Jh'yaah closet. Seciionm. 
 
 ScveetLsioseparctkcmdas 
 ii:om cah av^dixeci ihejaitei, 
 onia.-ihe excremettf. 
 
78 
 
 APPENDIX II- 
 
APPENDIX II. 
 
 79 
 
 Rochdale CorporatioTi 
 PaHem Pai/ closet. 
 
 iA. excremeTLt pail. 
 
 O. sea^ coyer (raised) 
 
 D iron collax ielcfw seat .reachmst HisflHiyinio 
 
 pail yrAen corer is donm.. 
 T.Mn^eduprigMotaecct, 
 Ql. door admMingAoiaov.t^h.%'eKatateni pail , 
 
APPENDIX III. 
 
 The following lucid description of the ventilation pf the 
 State Lunatic Asylum of New York, located at Utica, N. Y., 
 is taken, by permission of it? author, Dr. Jqhn P. Gray, from 
 the " Thirty-sixth Annual Report of the Managers of the 
 State Lunatic Asylum." 
 
 It is prefaced by a short extract from the report : 
 
 " The managers consider the method of heating and ven- 
 tilation of the institution to be the safest, most economical, 
 and best. Information is frequently sought as to the sys- 
 tem adopted. Recently an application made through the 
 State Department by the British government for a detailed 
 statement concerning the appliances and method, was re- 
 ferred to Dr. Gray, the superintendent of this institvitipri, 
 who made a report which was submitted to this board be- 
 fore transmission. The managers deem it such a clear and 
 succinct statement of the method adopted, that they ernbpdy 
 it as a document worthy of permanent record for use and 
 referejice. 
 
 Mode of Ventilating and Heating. 
 
 1. The mode of yeijtilatioij adopted is tl}|tt of forcing air 
 into the building by the use of two centrifugal fans, a draw- 
 ing. ^ndi description of which accompany this commuriica- 
 tioq. 
 
 2. Thg air is delivered fro^a the fans tp all parts of the 
 building. 
 
 3. Fir^t : Into |h^ I^fg^ plietupel or |}asemeut air du^t, 
 or air plenuiiq, which is continuous under the wh61e build- 
 ing. 
 
 6 
 
82 APPENDIX III. 
 
 4. Second : From this air duct or air plenum, the air 
 passes by flues into the various wards and rooms to be sup- 
 olied. Each flue is independent ; that is, it has an exit at but 
 pne point. These flues open into the wards or rooms to be 
 supplied at a point above the level of the top of the windows 
 and doors, so that no air movement caused by opening a 
 window or door will disturb the current of the incoming air. 
 The air is thus distributed uniformly through every part of 
 the building. 
 
 5. From the corridors and rooms flues are constructed, 
 starting just above the base-board, each flue passing inde- 
 pendently into the attic air chamber. Over part of the 
 building theie is ridge ventilation. Over other parts Of the 
 building the exit is through ventilators fixed at regular 
 distances. 
 
 6. Each fan delivers at each revolution 1 ,000 cubic feet 
 of air. They can be driven to supply almost any desired 
 quantity. They are here driven night and day, and supply 
 5,000,000 cubic feet of air per hour, which is a little over 
 100 cubic feet per minute to each occupant of the house 
 night and day. 
 
 7. The main air duct or plenum is large enough to con- 
 tain any quantity of air desired, without the need of a rapid 
 current. The area of the flues leading from this duct to the 
 wards and rooms is equal to forty-two inches for each occu- 
 pant. The exit flues from the wards and rooms to the attic 
 chamber is equal to sixty-four inches for each occupant. 
 The exit area through the ridge ventilation and ventilators 
 equals seventy inches for. each occupant. 
 
 8. In every single sleeping room there is a flue for the 
 exit of air of sixty-four inches area. In associate sleeping 
 rooms ihe area of the several fliies is equal to sixty-four inches 
 for each occupant. The flues for the supply of air open on 
 the corridors at the height already stated. The sleeping 
 rooms receive the air from the corridors at or near the floor. 
 
APPENDIX III. 83 
 
 In some of the wards there is no threshold under the door, 
 and the doors are shortened at the bottom to allow a space 
 between them and the floor of sixty-four inches area. In some 
 the air enters the sleeping rooms through a register in the 
 bottom rail of the door. In the associate sleeping rooms, 
 where sufficient air could not thus be obtained for several 
 patients, openings are made through the walls at points near 
 the floor. In a few of the rooms for the feeble the flues for 
 the supply of air open into the rooms. 
 
 9. This mode secures the most abundant supply of fresh 
 air. It secures what ventilation means practically : that is, 
 such constant dilution of the body of the air contained in the 
 building by fresh air sent in as to make it for all practical 
 purposes pure. 
 
 10. I do not use the words " fresh and foul air flues." In 
 reality, this method secures a constant flow of pure air 
 through the building from its entrance to its exit, and the 
 gradual enlargement of the areas facilitates the passage and 
 exit of the air, and compensates for the frictional resistance 
 in passing through the building. 
 
 11. It is stated in paragraph four that the air is intrO' 
 duced at a hei:^ht above the doors and windows. While 
 this is undoubtedly best, it is not absolutely necessary to 
 success in ventilation. It is proper to say that in a hospital 
 for the insane, it is advisable to have the air enter above a 
 point where patients would be likely to throw articles into 
 the flues, and also to avoid the evil of patients crowding 
 about the flues and impeding the thorough distributions of 
 the air. In the offices of the institution, in the residence of 
 the officers, and some of the rooms not constantly used in 
 the hospital proper, the air is introduced just above the base- 
 board, and in some instances through the floor ; but in all 
 cases, no matter where the air is introduced, the exit flues 
 should start from near the floor as already described. Where 
 the air is thus introduced, it is important to locate the flues 
 so as not to have them opposite windows. 
 
84 APPENDIX III. 
 
 12. Where the rooms are large, as in case of parlbts and 
 sitting rooms, and require two or more flues for the intro- 
 duction and exit of air, it is important to distribute them so 
 ttiat all parts of the rooms shall be supplied uniformly. 
 
 13. Heating is combined with ventilation. The aib is 
 warmed to the degree required by being compelled to pass 
 over cast iron radiators, through which steam is circulated, 
 on its way from the fan to the occupied parts of the build- 
 ing. These radiators are placed in the main air duct or 
 plenum, and are in separate blocks directly underneath the 
 flues leading from this duct to the occupied parts of thfe 
 building. There is a box of radiators for each set of three 
 flues, one flue leading to each story. Each block has an iti- 
 dependent connection with the main steam pipe, so that 
 each bldck can be used separately. Each block is cased in 
 on the sides leaving the bottom open for the free passage of 
 aii" over the radiators. By this arrangement the air is 
 warmed at the nearest point of its delivery for use, and the 
 heat is not wasted by absorption into the walls of a large 
 general air chamber, and the temperature of the air sent 
 ihtb dny specidl part of the building can be regulated as 
 may be desired, simply by introducing more or less steam 
 into the individual blocks. 
 
 14. Thesfe radiators are so constructed and connected as 
 to liiak'e Vhat is called a " steam coil," and the blocks are 
 So a,ri:aliged and connected that steam can be turned upon 
 ah'e-third, two-thirds, or the whole, as the atmospheric tem- 
 peiratUre inay require. Of cburse, there is no impediment 
 to the passage of the air through these blocks for summer 
 ventilation when heat is not needed, as the space between 
 them is sufficient for the passage of the Idrgest volume bf 
 air requited. 
 
 15. This large body of air entering and distributed in the 
 manner described produces no appreciable current. It is 
 not found necessary to raise the temperature of the air in- 
 troduced higher than 100 degrees at the point 6f ""entt-adce 
 
APPENDIX III. 85 
 
 to the wards and rooms, in order to secure a general tempe- 
 rature of seventy degrees throughout. Thus the air is not 
 rarified, expanded, or dried, to a degree that interferes with 
 healthfulness and comfort. 
 
 16. This system does not require registers ta control the 
 temperature of the room by closing and unclosing them. 
 The amount of air delivered over each radiating block is 
 Warmed to the temperature there required, and as the vol- 
 ume of the air delivered is uniform and constant, thorough 
 ventilation is obtained. Registers in the wards of a hos- 
 pital would be likely to be used to close off the flow of air if 
 it was too warm, that being easier done than to give infor- 
 mation to the engineer having control of the heating blocks. 
 Registers are used in the offices and residences of the officers. 
 
 17. It is possible to determine the exact amount of coal 
 necessary to raise a given amount of atmosphere one degree, 
 and this gives the key to the necessary amount of coal to be 
 burned in the steam boilers to raise the whole quantity of 
 air introduced to any* desired temperature. The engineer 
 by observing the temperature of the external atmosphere, 
 and knowing the volume of air delivered, can, with suffi- 
 cient accuracy, supply the necessary amount of heat. 
 
 18. To illustrate : The cubic capacity of the wards and 
 rooms of this asylum is, in round numbers, about 5,000,000 
 feet. Five million cubic feet of air sent in by the fans per 
 hour night and day. Twelve pounds of coal will raise this 
 atmosphere one degree per hour. At this writing the aver- 
 age outside temperature for the past twenty-four hours has 
 been ten degrees below zero. The temperature of the wards 
 has been maintained at from seventy to seventy-two, and we 
 have burned 8 tons and 1,280 pounds of coal, an average of 
 720 pounds per hour; the actual number of occupants 722. 
 
 DESCRIPTION OF FAN. 
 
 The fan and its support are of iron, the casing of wood • 
 
86 APPENDIX in. 
 
 the rotary or operating part of the fan consists of a 
 shaft with eight radial arms set back on a curve at the 
 extremities of which are fastened iron wind boards, 
 three feet wide and five feet long, in the direction of 
 the axis ; the extremities of the wind boards are six feet 
 from the center and consequently describe a circle of twelve 
 feet diamter. The sliafc extends beyond the casing and 
 rests on pulley blocks, and on the driving side it is length- 
 ened six feet to receive the driving pulley and remove all 
 obstruction to the easy entrance of air to the fans ; the mo- 
 tion is imparted by a belt passing over the pulley, four feet 
 in diameter, with ten-inch face, on the end of the shaft, the 
 arms and boards revolve within the wooden casing, the cir- 
 cumference of which instead of being concentric with the 
 shaft, describes a curve of increasing diameter and forms 
 outside the wind boards a channel of constantly enlarging 
 capacity towards the point of delivery. The casing is there- 
 fore scroll-shaped, this space being six inches in front and 
 enlarging to three feet at the bottom. The height of the 
 casing from the floor is eighteen feet. The cross-sectional 
 area is equal at the point of delivery to forty-two square 
 feet. The opening in each side of the fan-casing, for the 
 inlet of air, is six feet in area. This whole machinery is 
 placed in a room, the floor of which is on a level with the 
 floor of the main air duct, and the air is admitted through 
 a large open space, double the area of both inlets, and 
 properly guarded.