LIBRARY 
 OF THE 
 
 UNIVERSITY OF ILLINOIS 
 
 NORTH CAROLINA BOARD OF HEALTH. 
 
 SANITARY ENGINEERING, 
 
 THIRD EDITION. 
 
 BY 
 
 c_ e.. 
 
 Former Member or the North Carolina Board of Health. 
 
 THE LIBRARY OF THE 
 
 NOV 11 1938 
 
 UNIVERSITY OF ILLINOIS 
 RALEIGH : 
 
 P. M. HALE, State Printer and Binder. 
 1885. 
 
PRESSES OF 
 
 E. M. UZZELL, 
 
 RALEIGH, N. C. 
 
SANITARY ENGINEERING. 
 
 (THIRD EDITION.) 
 
 By WILLIAM CAIlSr, C. E. 
 
 CHAPTER 1. 
 
 GENERAL CONSIDERATIONS. 
 
 It is only within the last few decades that Sanitary Engineer- 
 ing, which is concerned with the proper methods for the dis- 
 posal of the refuse of our towns and cities, has claimed the con- 
 sideration of scientific men, although its importance has been 
 recognized from the earliest times — in fact so soon as men began 
 . to congregate in towns and cities or even in encampments. The 
 light which modern chemistry sheds upon chemical reactions and 
 . decompositions and the practical value of the extended researches 
 ^in the laws of the flood of liquids and gases, form the data, 
 together with recorded experience, by which the modern sanitary 
 engineer devises systems of sewerage to meet the wants of any 
 community. 
 
 ^ Death eates lowered by sanitary works. — We are told 
 ^ upon the best authority that in England there occurs annually 
 upwards of four million cases of preventable sickness; and that 
 ^ 125,000 persons are prematurely cut off every year from a neg- 
 ^ lect 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 gen- 
 ^erally made in meeting doctors^ hills, diud funeral expenses? 
 
 It is further stated that in England, since the sanitary precau- 
 tions have been instituted, that the death rate has been^ lowered 
 
4 
 
 SANITARY ENGINEERING. 
 
 by from cne-fourth to one-tliird, and is besides decreasing from 
 year to year. The following table, referring to a few localities 
 in England, taken from Latliam^s Sanitary Engineering,’^ 
 speaks more forcibly than all the other arguments that may be 
 presented, especially to those who have paid but little attention 
 to sanitary subjects, and are inclined to be skeptical as to the 
 great actual saving of life that may be attained : 
 
 Name of Place. 
 
 Population 
 
 in 
 
 1861. 
 
 1 Average mor- 
 
 1 tality per 1,000 
 
 before con’tion 
 
 1 of works. 
 
 1 Average mor- 
 
 1 tality per 1,000 
 
 I since complet’n 
 
 1 of works. 
 
 Saving of life. 
 
 Per cent. 
 
 Reduction of 
 
 typhoid fever. 
 
 Rate per cent. 
 
 Reduction in 
 
 rate of phthisis. 
 
 Per cent. 
 
 Banbury 
 
 10,238 
 
 23.4 
 
 20.5 
 
 12^ 
 
 48 
 
 41 
 
 Cardiff, 
 
 32,954 
 
 33.2 
 
 22.6 
 
 32 
 
 40 
 
 17 
 
 Corydon, 
 
 30,229 
 
 23.7 
 
 18.6 
 
 22 
 
 63 
 
 17 
 
 Dover, 
 
 23,108 
 
 22.6 
 
 20.9 
 
 7 
 
 36 
 
 20 
 
 Elv, 
 
 7,847 
 
 23.9 
 
 20.5 
 
 14 
 
 56 
 
 47 
 
 Leicester, 
 
 68,056 
 
 26.4 
 
 25.2 
 
 
 48 
 
 32 
 
 Macclesfield, 
 
 27,475 
 
 29.8 
 
 23.7 
 
 20 
 
 48 
 
 31 
 
 Merthvr, 
 
 52,778 
 
 33.2 
 
 26.2 
 
 18 
 
 60 
 
 11 
 
 Newport, 
 
 24,756 
 
 31.8 
 
 21.6 
 
 32 
 
 36 
 
 32 
 
 Kugby, 
 
 7,818 
 
 19.1 
 
 18.6 
 
 2i 
 
 10 
 
 43 
 
 Salisbury, 
 
 9,030 
 
 27.5 
 
 21.9 
 
 20 
 
 75 
 
 49 
 
 Warwick, 
 
 10,570 
 
 22.7 
 
 21 
 
 n 
 
 52 
 
 19 
 
 A previous statement would indicate that the death rate is still 
 being steadily lowered. As Latham states, the most healthy dis- 
 tricts 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 mea- 
 sures 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, ranging 
 from 17 to 30 in 1,000 generally; but St. Louis shows a death 
 
GENEKAL CONSIDERATIONS. 
 
 5 
 
 rate of only 11, which apart from its site, ‘‘must be ascribed 
 largely to its excellent water su[)ply and sewer system.’’ 
 
 Economical Aspects. — Apart from the humanitarian view 
 of tins question, it may be considered in its economical aspects: 
 thus Latham has taken Croyden, where the total cost of sewers, 
 &c., was $943,800, and estimated the saving m funerals ^ in sick- 
 ness (allowing that for every life saved 25 would escape sick- 
 ness, the saving being estimated at $5 for every sick person) 
 and in the labor, for years only, by the prevention of pre- 
 mature 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 fever 
 its origmf In the filthiest port in the world, Havana, where, 
 “the tide being almost imperceptible, all the emptyings of the 
 sewers remain in the harbor until they become a foetid and revolt- 
 ing 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. 
 
 General Butler at least has the merit of having to a great extent 
 kept New Orleans clean 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 energetic 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. Huntsville,/ 
 Ala., actually sheltered yellow fever victims with impunity ; 
 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 pecuniary gain to the 
 community, even including the cost of sanitary works. Health, 
 
6 
 
 SANITAKY ENGINEERING. 
 
 population and money values also, generally go hand in hand, 
 when other conditions are favorable. 
 
 On the contrary, if we disobey the Divine Will, by running 
 counfer to natural laws, we are punished for the sin of disobe- 
 dience. 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 cleatdiness, which, the Good Book tells us, is next to god- 
 liness. 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 sufficiently accounted for by bad wellsy 
 foul yards, privies, and cess-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 otie 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 onl^ his neigh- 
 bors 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 
 nature of the poison generated by filth we know little; but it 
 has certainly been demonstrated in numerous cases that the rav-i 
 ages of epidemics are in direct proportion to the foulness of the 
 locality. Thus in one city, diphtheria foTlowed 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 furnished 
 with un filtered Thames water with three-and-a-half times the 
 severity experienced by neighboring districts supplied with 
 Thames water filtered through sand and charcoal. 
 
 It has become, as it were, an accepted truth in sanitary science 
 that the fatal effects of epidemics may either be prevented, or 
 
GENERAL CONSIDERATIONS. 
 
 7 
 
 their spread materially hindered by a proper attention to sanitary 
 precautions. These precautions simply consist in the having, at 
 all' times, _pi6re air, wholesome food, and good water. It is only 
 the first and last of these requisites that will be considered in 
 what follows, as they pertain more especially to the scieiice of 
 “Sanitary Engineering’^; though it is to be observed that whole- 
 some food is to a certain extent dependent upon the good water 
 or milk used in the cooking. 
 
 By a disregard of these pi*erequisites to health — and they are 
 more or less disregarded by us all — we enfeeble the system, suf- 
 fer 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 atmos- 
 phere. 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 giviug mainly 
 those principles and facts that should be known by every one. 
 Any system proposed must be a simple one — the simplest is 
 generally the best — to meet the needs and comprehension of all 
 classes. 
 
 The law organizing the N. C. Board of Health requires a 
 monthly report from each county on vital statistics. It is of 
 great importance that this law be faithfully carried out, so that 
 the effect of the suggestions given below, where carried out, may 
 be ascertained. 
 
 The same act requires that the Board “shall gather informa- 
 tion, for distribution among the people, with the especial purpose 
 of informing them about preventable diseases.” 
 
8 
 
 SANITARY ENGINEERING. 
 
 Disease may be prevented, other conditions being favorable, 
 by a proper attention to drainage, ventilation, water supply, and 
 the prompt disposition of sewage matters. 
 
 We shall consider the subject in the above order. 
 
 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 ^^co!d’’ and ^‘sour’^; and that by drainage such 
 lands are often converted into the best quality of lands, owing 
 to the replacement of the excess of water and vegetable acids by 
 warm, dry air, so that the roots now find the proper amount of 
 air, moisture and temperature to satisfy the conditions of growth. 
 
 The sun’s rays now cause a healthy decomposition of organic 
 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 
 off into the air. 
 
 It is the latter that produce, indirectly or otherwise, the inter- 
 mittent and remittent fevers, so common over the whole South. 
 The best cure is drainage. 
 
 ^‘The feus of Lincolnshire, in England, and marshy districts 
 along the lower Thames were formerly greatly scourged with 
 fever and ague and with malarial neuralgia. The extensive 
 y drainage operations carried on in these districts have had the 
 effect of removing these ailments entirely.” 
 
 Where ground is water-logged, it is unfit for human habitation. 
 
 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 vvill be more fully explained 
 further on. 
 
DRAINAGE. 
 
 9 
 
 Maeariae 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 alternately 
 wet and dry, are such as originate malarial poison, and must con- 
 tinue to originate it so long as such conditions hold. The occa- 
 sional overflow of salt water aggravates the evil, as also the 
 accumulation of leaves, decaying wood, etc., especially where 
 thick vegetation causes a stagnation of the air, with dense shade. 
 It is obviously correct then to cut down such vegetation imme- 
 diately around the dajup locality, drain it and put it under culti- 
 vation. If the rise and fall of the water, 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 entirely 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 intercept the malaria 
 to a considerable extent. 
 
 It is very often the case that dwelling-houses, in city and coun- 
 try both, are surrounded with such a dense mass of .shrubbery 
 (perhaps intended to satisfy the aesthetic taste) as to cut off b<flh 
 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 ‘^lonored in the 
 breach^’) to deny earnestly and with many asseverations that 
 malaria affects the locality one lives in. Sad must be the con- 
 dition of that person, who, even if he admits an occasional 
 malarial fever, cannot point out another locality where the ma- 
 lady is infinitely more distres.sing. 
 
 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 sub- 
 ject to it to a greater or less extent, and therefore that thorough 
 
10 
 
 SANITARY ENGINEERING. 
 
 drainage is one of the first requisites to increased healthfulness. 
 Whilst thinly settled districts may not be able to institute pro- 
 per precautions, yet the larger towns can drain thp ponds, low 
 places, roads and mother earth generally in their vicinity. 
 
 In the last column of the previous table is seen the reduction 
 in the death-rate from phthisis of twelve English towns, “This 
 saving of life is ascribed to the effect of drainage works in dry- 
 ing 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 dimin- 
 ished 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 
 {)reference 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 stag- 
 nant 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 purposes 
 by stone or pipe drains of 1 to 2 inches diameter, running 
 straight down the hill-sides (when not too steep) in parallel rows,. 
 25 to 50 feet apart, and 30 to 36 intdies below the surface. 
 These small drains discharge into larger intercepting drains, run 
 down the hollows; and these, in turn, empty into larger drains 
 (that may often be open) that follow 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 (»f agriculture, but is in perfect keeping with 
 the requirements of health. Towns sliould at least keep the sub- 
 soil dry, by covered drains run along the streets and elsewhere, 
 at sufficient de[)ths to drain the cellars thoroughly and to [)revent 
 standing pools of water. 
 
 Tile drains 2 inches in diameter, under the side-ditche», or one 
 3-inch drain under the middle of the road, is sufficient generally. 
 An outlet drain should run from the depressions in the road. A 
 
DRAINAGE. 
 
 11 
 
 drain or culvert crossing the road should be large enough to pass 
 2 inches of rain-fall in one hour when the drainage area is small, 
 1 inch for a valley two to three miles long, and so on. 
 
 All streets and roads should be built higher in the middle 
 than at the sides, and should have gutters deep enough to carry 
 olf storm waters, unless there are specially constructed large 
 drains for this purpose (as to which, and also the subsoil drain- 
 age of houses, 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 absorbed by 
 the ground) are contemplated, regard must be paid, in laying 
 them, to the future sewerage of the^town, even if this is not car- 
 ried on at the same time as the drainage system {)ro[)er. 
 
 The drainage of large districts, swamp lands, low lands, etc., 
 varies so with the configuration of the ground that it is impossi- 
 ble 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, fol- 
 lowing the natural slope of the plateau with a fail of 1 to 2 per 
 1,000. Of these canals 1,600 miles have been eompleted. For 
 75 miles along the coast, huge sand-banks protect the coun- 
 try 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 reclaimed land is estimated at up- 
 wards of $56,000,000. 
 
 ^^The fevers which formerly ravaged the country have disap- 
 peared, and the country may now he considered one of .the most 
 healthy in France.” 
 
 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 embankment. 
 
12 
 
 SANITARY ENGINEERING. 
 
 Straightening the course of rivers, likewise, is efficient in 
 causing increased scour, a lowering of the bed and a lessened 
 liability to overflow. 
 
 Ponds are easily drained by simply cutting a ditch of the 
 pro{)er size through the natural or artificial embankment sur- 
 rounding them. The greater the extent of the water-shed, and 
 the greater the rain-fall, and the imperviousness of the surface, 
 the larger of course is the ditch. 
 
 The so-called ‘‘wet weather’^ ponds, often on high ground, 
 should never be tolerated, as they present the very conditions 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 inconvenience 
 ha’s been caused in some thickly settlerl 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 character of the 
 soil, whether very retentive or porous. Their action is analogous 
 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 November’^ 
 in malarial districts, unless for house drainage. Cellars should 
 be drained by leading a pipe from below the bottom of the cel- 
 lar to some convenient exit to the open air 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 drainage in 
 towns near our sea-<*oast than in the hilly regions, as decomposi- 
 tion is generally greater, due to increased moisture and tempera- 
 ture, not forgetting however that its neglect anywhere must 
 cause pernicious effects. 
 
 ^See Kerr’s Geology of N. C. (Introduction) for an excellent presentation 
 of the leading topographical features of the State, especially its swamps and 
 pocosins, as relating to the matter in hand. 
 
VENTILATION. 
 
 13 
 
 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 impurities that 30 years is the maximum age 
 attained by the operatives. Such instances (and they may be 
 multiplied), though they indicate criminal neglect in the man- 
 agement, are fortunately exceptional, and need not be considered 
 here. 
 
 The impurities that we. shall consider under this head, as con- 
 cerning 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 volume 
 nearly 1-5 oxygen to 4-5 nitrogen, with small variable amounts 
 of aqueous vapor, ammonia, carbonic acid and certain micro- 
 scopic organisms, besides dust, etc. 
 
 If phosphorus is burnt in a bell jar, placed over water, it com- 
 bines with nearly all of the oxygen in the confined air, forming 
 white fumes of 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) now remaining 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 cholorate, etc^), is likewise colorless and inodorous, 
 but it supports combustion readily — iron even burning (oxidiz- 
 ing) in it with great brilliancy. 
 
 The oxygen is the life-giving principle of the air. An animal, 
 however, exposed to pure oxygen gas is overstimulated to such 
 an extent that it soon dies. The nitrogen, therefore, 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 con- 
 
14 
 
 SANITAEY ENGINEERING. 
 
 sequences 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 oxygen 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 nitro- 
 gen 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, dew, 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 cannot hold any more water gas, 
 as gas, any excess being precipitated as rain, or formed into the 
 liquid particles constituting fog or cloud and becoming therefore 
 visible. • In fact, suppose air, saturated at 90°, to be cooled down 
 to 32° suddenly: then 12.13 grains of rain will fall for every 
 cubic 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 rain, 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 
 
VENTILATION. 
 
 Id 
 
 ^‘relative humidity.’^ This gives the percentage of full satura- 
 tion of the air at the time of observation. Thus, relative 
 humidity 60,^’ would indicate that the air contains 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 : Wilming- 
 ton 57, Charlotte 65, 8t. Louis 67, London 80 and New Orleans 
 86; the first two giving only the mean from a little over one 
 year’s 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 deleterious 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 ame- 
 liorated 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 high- 
 est 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. 
 
 Another important constituent of the air is ammonia, though 
 it exists in comparatively 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 ofi* from urine and stable manure, unless gypsum is 
 added to fix it. It is not injurious by itself in small quantities, 
 and need not be further considered. 
 
 The most important, by far, of the inorganic air constituents, 
 next to oxygen, is carbonic acid. Its amount varies within wide 
 
16 
 
 SANITARY ENGINEERING. 
 
 limits; thus in Scotland, mountain air contained 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 decompositions, 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 car- 
 bonic acid expired is only 5 per cent. The lungs and body like- 
 wise exhale impurities, about in proportion to the amount 
 
 of carbonic acid thrown off, the nose readily detecting the vitia- 
 tion due to this cause. It is thought by many that these organic 
 impurities — fatty matters thrown off from the skin, particles of 
 skin, odors, etc., from man and beast — although constituting 
 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 doubt are scavengers, but 
 others are thought by some to cause disease. 
 
 The Atmospheric Germs. — It is well known now that fer- 
 mentation 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 knowm as yet, but the theory is at least plausible, and 
 explains many facts more fully than any other theory generally 
 known. 
 
VE^’TILATION. 
 
 17 
 
 Wl' know this much, that sewer gas, even in the tninutest 
 quantity, is sometimes fatal (which is not due to the chemical 
 gases formed, lor the chemist breathes them every day), at(»ther 
 times innocuous, especially when free ventilation has been secured. 
 Similarly the discharges, and even garments, of patients suffering 
 witli certain fevers can communicate 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 us(i 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. — I t is found that a man gives off somewhat over 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 much carbonic acid per 
 hour as two or three peUple. It is true that the gas gives off 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 supply at least 
 1,000 cubic feet of pure air in every hour to dilute the ^ 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 person, since the ^ of 
 carbonic acid admitted, added to the expired per hour, gives 
 the ratio of 12 to 20,000 or 6 to 10,000 allowed. 
 
 2 
 
18 
 
 SANITARY ENGINEERING. 
 
 It is said by some, that experience in hospitals shows that 
 from 2,000 to 3,000 cubic feet of fresh air should be admitted 
 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 provided. 
 
 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 conse- 
 quence 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 jets burning. At the same temperaturSy 
 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. Fortunately, 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 eleva- 
 tion of a locality. 
 
 Where a room has no flue or chimney to keep up a constant 
 circulation, then openings should be provided near the top of the 
 room to let the warmer impure gasses out, and not let them cool 
 and descend again to vitiate the air we biTathe. 
 
 Vitiation by Perspiration. — In addition to the carbonic 
 acid given off by the lungs and skin of a man, there is exhaled 
 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 aver- 
 age. A high temperature, or exercise, causes greater perspira- 
 tion, thus cooling the person somewhat. 
 
VENTILATION. 
 
 19 
 
 The amount of moisture given off is considered by some in 
 connection with the carbonic acid exhaled, to ascertain the theo- 
 retical amount of air to admit; but this theoretical amount for 
 most houses is larger than healthy persons seem to require, ac- 
 cording to certain experience. This is accounted for by the fact 
 that opening doors and windows, especially if they are kept open 
 for some time, the draft through cracks, &c., add very much to 
 the volume of admitted air, though not considered in the com- 
 putation. 
 
 Lime as a Purifier. — If a house has been lately plastered 
 or whitewashed, 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 required 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, therefore, 
 that a plastered wall whitewashed was better than either the 
 ^^hard finish or papering. The accumulation of filth in succes- 
 sive coats of papering in old houses is probably frightful. Most 
 of us have seen the trunks of trees whitewashed. 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 carbonic acid out of doors, where it is not in ex- 
 cess? 
 
 The Leaves of Plants as Purifiers. — The carbonic acid 
 thrown ofP into the air by decomposition, lightning, 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 car- 
 bon 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 ventilation schemes, but have to 
 resort to heated currents or to fans to expel the foul air from our 
 rooms and leave it to nature to carry the foul air by the winds to 
 
20 
 
 SANITARY ENGINEERING. 
 
 her millions of laboratories and return it to us pure. If there 
 was no vegetable 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, tdth comfort, in a room, as often as the winds do, out of 
 doors ; but we can easily prevent the air in the rooms from . be- 
 coming 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 through every possible outlet, and cool 
 fresh air coming in to take its place. In very open houses, ven- 
 tilation is often secured 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 containing an 
 open fire-place. A fire must be kept brightly burning in the 
 fire-place, to heat the air in the chimney or flue, causing a differ- 
 ence 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 men- 
 tioned 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 precaution 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 ^re simple in the extreme. 
 
 Thus, if the lower sash of the window is raised a few inches 
 and the opening below it 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 grad- 
 ually diffused through the room without draft. 
 
VENTILATION. 
 
 21 
 
 A common expedient of simply lowering the top sash allows 
 the cold air to “trickle down’’ on our heads. In the latter case, 
 however, a board may be placed at an inclination against the 
 upper part of the sash, so as to give the entering current an up- 
 ward 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 part of the 
 doors or walls, and giving the entering air an upward direction 
 by means of inclined planes of some kind; or tubes of wood or 
 iron may be passed through the walls and turned directly up- 
 wards on entering. They should extend 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 openings, moreover, 
 should admit of being partially or entirely closed on very stormy 
 .and windy days. All of the above plans hav^e been tried in 
 dwellings, club-rooms, etc., with complete success. 
 
 The proper size of tube or opening to use must be determined 
 by experience. Two tubes, of two inches diameter each, may be 
 tried for an average- sized room for two persons. It is stated 
 fhat “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° F., 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 the same 
 
22 
 
 SANITARY ENGINEERING. 
 
 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 part of its volume for 
 each degree Fahrenheit above or below the freezing point, the 
 pressure remaining the same; so that 491 volumes of 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 0.2374 lbs. of water 
 through one degree, the air being subjected to constant pressure. 
 
 From such data, in connection with the heat afforded by dif- 
 ferent fuels, and the laws affecting the flow of gases, we are ena- 
 bled to compute the velocity of the air flowing out of the chim- 
 ney, 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 out-doors 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. ScuddeFs 
 church) being 150x100, of the other (Dr. Hepworth’s) 125x125; 
 the first seating 2,200 and the second 2,400. There were four- 
 teen to twenty twelve-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 is an opening in the centre of the ceiling of 
 the auditorium into an octagon-shaped shaft eleven feet in diam- 
 
VENTILATION. 
 
 23 
 
 eter iu onfe church, sixteen in the other, extending alxwe roof, 
 containing sashes and outlets to the outer air. -Gas jets are 
 placed under tubes in these shafts to increase the current. At 
 other {)arts of the ceiling are similar shafts, etc. The numerous 
 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 propelled along 
 ducts — -.over steam pipes or furnaces, if it is to be heated — to 
 openiijgs 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 New York Lunatic Asylum). 
 
 Good Effects of Ventilation. — It is evicieut how im- 
 portant a factor of healtli ventilation is in crowded school-rooms; 
 in fact, in all places where crowds may congregate and speedily 
 vitiate the air. The bad effects are everywhere admitted. The 
 ^ood effects of the systems proposed have been proved by mor- 
 tuary statistics, especially in school-houses and hospitals. In a 
 Dublin hos[)ital, in 1783, for twenty-five years when the venti- 
 lation 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 twenty-eight years, 550 died out of every 
 15,072. 
 
 The report of 1861 states that further improvements in ven- 
 tilation 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 
 
24 
 
 SANITARY ENGINEERING. 
 
 the smoke resulting from the burning of coal is charged with 
 impurities, such as “hydrocarbons, sulphide of ammonium, ‘car- 
 bonic oxide, and probably very minute quantities of arsenic.’’ 
 Even now the cry is going up from London for a purification of 
 its atmos})here from smoke. This evil 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 build- 
 ings 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 hails, which is five times 
 the admissible amount, it will be admitted that reform is needed. 
 
 Cubic Space Allowed. — The amomit of space per head 
 allowed in the roQm by various autho7'ities, 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 
 objectional)le. The amount of space actwdly given per head in 
 various school-houses varies from 70 to 100 to 200 cubic feet. 
 The effect is that 12 parts of carbonic acid in 10,000 (double 
 the admissible amount) is common, and even 20 and 50 parts are 
 not unknown.. The effect upon both teacher and pupils is of 
 course, headaches, listlessness and debility. 
 
 Lighting.— The proper lighting of school-rooms is as ut*ces- 
 sary as ventilation. The light should come from behind th^ 
 pupil on to the book or blackboard, when possible, and the win- 
 dows 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 o})f)Osite 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 too near the eyes, so that the tendency to near-sight- 
 edness may be prevented. This detect is becoming alarmingly 
 {irevalent, and tlie teacher should insist upon the pupil reading 
 
V^ENTILATION. 
 
 25 
 
 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 out-doors 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 transmit 
 gases. “Pettenkofer got 2,650 to 3,320 cubic 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 cran- 
 nies had been carefully stopped up, 1,000 cubic feet per hour still 
 came through the walls.’’ Therefore never aPow filth about any 
 room or cellar of the house, nor against the outside walls, for 
 such filth will contaminate 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 pur- 
 est 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 heating; 
 in fact the two have generally to be considered together. 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 o'f the country that 
 invigorates body and mind. 
 
 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 
 
26 
 
 SANITAKY ENGINEERING. 
 
 with a dryiijg-house. Let us understand clearly the physical 
 differences in the various methods of heating, and we can then 
 form a more intelligent judgment 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 rays, which pass through the intervening air 
 with scarcely any loss. Tyndall has shown that air, consisting 
 simply of oxygen and nitrogen, intercepts but an extremely 
 small number of heat rays passing through it. The aqueous 
 vapor, found in all air, intercepts 30 to 100 times the heat that 
 pure air does. Carbonic acid, perfumes, etc., increase the absorp- 
 tion of heat by air. The water gas in the atmosphere, although 
 constituting only, say J [)er 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 
 Tyndall says, “Aqueous vapor 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 between 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 efficient draught 
 to keep the air from being too much fouled. 
 
 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 con- 
 tact. The warming is mainly eff'ected, as in the case of stoves 
 (not overheated) 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. 
 
VENTIJ.ATION. 
 
 27 
 
 The aiv is thus warmer than the furniture in the room ; whereas 
 in heating by the open fire-place, the furniture, etc., is often 
 warmer than the air. A person in the room would thus be con- 
 tinually radiating heat, unless the air was too warm for comfort. 
 In addition to the objection to the warm air_per se, it has been 
 previously explained that heating air causes it to become tpo 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, as a 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 Northeru 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 supplement 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 Jen- 
 kin, in “Healthy Plouses” (Harper’s 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 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 diflused through the room, the cold air taking 
 its place to be in turn heated, &c. 
 
 Iron stoves, especially when overheated, emit a bad smell, 
 supposed to arise from the charring or decomposition of organic 
 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 
 
28 
 
 SANITAEY ENGINEERING. 
 
 and thus enter the room. The air is charred and dried too much 
 by iron stoves. The porcelain are far preferable. Hot-air pipes 
 are better, and moreover distribute the heat more uniformly; 
 though if the furnace becomes red-hot, poisonous carbonic oxide 
 will pass into the pipes. Some describe the ^‘hot air” as having 
 the ^Mife taken out of it.” Hot-water pipes are better than hot- 
 air pipes; the air is not overheated, and a uniform temperature 
 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 sys- 
 tem, the water-pipes or the gas-stoves are used. For comfort 
 and cheerfulness, no device can e(^ual 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 grad- 
 ually diffused through the room as it becomes heated, to give up 
 the proper amount of oxygen required for respiration and com- 
 bustion. 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? 
 
 CHAPTER IV. 
 
 WATER SUPPLY. 
 
 All of our supplies of water are derived from rain-fall, part of 
 this rain-fall 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 form- 
 ing the small subterranean streams which furnish the water of 
 our springs and wells. In running 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, giv- 
 ing the pleasant taste to our usual potable waters. 
 
WATER SUPPLY. 
 
 29 
 
 Other salts and gases, derived from decaying .organic matter — 
 dead bodies, manure, filth, etc. — are harmful in the highest 
 degree, and have bred mischief and death in innumerable cases. 
 
 The rain as it leaves the clouds is pure water generally; but 
 in falling to the ground, it not only carries with it mechanically 
 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 the pro- 
 cesses used in the particular manufacture. Water readily dis- 
 solves certain gases. On simply shaking it up with air, the lat- 
 ter is readily dissolved. This principle is made use of in aerat- 
 ing 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 ammonia 
 commonly found in waters is small, particularly the ammonia; 
 which last, it may be observed, water can dissolve in large quan- 
 tities. All of these gases are easily expelled by simply boiling 
 the water. 
 
 Rain water generally contains far less organic matter than 
 river water. River waters, though, differ greatly in the amount 
 and character of the matter, in solution and suspension, as re- 
 gards potability. Thus, if water drains over an impervious stra- 
 tum, as a granitic formation, the water is apt to be soft, and to 
 contain but little solid matter in solution. 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 otherwise of the best character. 
 
 Where the rocks consist largely of carbonates of lime or mag- 
 nesia, the waters are apt to be hard, their action on lead and iron 
 pipes is small, and they require a greater expenditure of soap in 
 washing, but are not otherwise objectionable, unless the carbon- 
 ates are greatly in excess. 
 
 It is stated that the health and physique of hard water dis- 
 tricts is better than in soft water districts; the water furnishing 
 an abundance of material needed in the formation of the bones. 
 
30 
 
 SANITARY ENGINEERING. 
 
 Each ^‘degree of hardness (i. e., each grain of chalk or sul- 
 phate of lime, dissolved in a gallon of water) will entail, how- 
 ever, 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 con- 
 tains carbonic acid in solution, when it can dissolve very much 
 more* 
 
 Boiling expels this acid ; thus reducing the amount of carbon- 
 ate 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 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 quantity of 
 quick lime in water. 
 
 Permanent hardness of water is caused by the presence of sul- 
 phates of lime and magnesia. Neither boiling nor Clarke’s pro- 
 cess can soften such water. 
 
 Wells and Sp^iings. — 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 matter, which 
 by oxidation and putrefaction readily forms soluble nitrates, am- 
 monia 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 chem- 
 ical 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 contamina- 
 tion. 
 
WATER SUPPLY. 
 
 31 
 
 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 opposite 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 fiow 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 subterranean 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, slops, manure or any kind of fecal matter 
 can drain into them. Where no stratification, exists, then, if 
 possible, place the well two or three times its depth from any 
 offending 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 estab- 
 lishment were thrown w'here 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 entering it and 
 that it may induce a flow from a considerable extent of the sur- 
 rounding earth. Chemical analysis o^n alone show if some of 
 these little streams have been polluted; in fact, whether a well 
 is the drainage receptacle of the filth on the surface or of the 
 rotten cess-pool — the disgrace 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. 
 
32 
 
 SANITARY ENGINEERING. 
 
 The water thus coutaiued in the ground is known as the “soil^^ ’ 
 or ‘Aground’’ water. Where the earth is porous, absorptive and 
 uniform in character, much more of the rain-water passes into 
 the ground to flow oflP along subterranean channels to some out- 
 let, to appear at the surface again as springs, 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 saturation generally 
 rises with the ground, so that generally as 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 uniformity in the strata or in the con- 
 figuration 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, fissured 
 or faulted. 
 
 Some special cases may be given however. Thus if a porous 
 stratum overlies an impervious one, the water descends through 
 the former until it reaches the latter. Now as the lower stratum 
 ij level, or slopes towards its outcrops, or is depressed in the 
 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 districts) a good 
 supply of water may be expected. 
 
WATER SUPPLY. 
 
 33 
 
 111 the latter case, if the porous strariiin is again underlaid 
 with an impervious one which is depressed in the middle, large 
 quantities of water will collect in this basin under consid rable 
 hydrostratatic 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 resorted to in some countries. 
 
 In this State we need have no fears of a water famine if the 
 various sources are utilized. In the Quarternary sand of 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 causing abnormal features: still, as the dip, 
 except in the sandstone 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 ob- 
 served, that even when the well is situated near a stream, that 
 “ the water is generally clear and colorless, of a nearly uniform 
 3 
 
34 
 
 SANITARY ENGINEERING. 
 
 temperature, and differs in chemical character from that of neigh- 
 boring streams or ponds, generally being somewhat harder.^’ 
 
 On lowering the level of the water in such basins by pumping 
 or otherwise, the ground-water level is lowered next the basin to 
 the same extent; but it is found that as we proceed from the 
 well or basin, that this level is lowered less and less, until we 
 reach a point which is not affected 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 constantly 8.2 feet below its normal level, that the 
 height of the ground-water was affected in every direction 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 tow^ards 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 examples 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 di 
 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 system 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 mat- 
 
WATER SUPPLY. 
 
 35 
 
 ters, and by the oxygen condensed in its pores, frees the water 
 of a small portion of its organic matter. 
 
 As the sand becomes clogged, it is scraped off at top and 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 twofold, 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. 
 
 2d. 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 w|Lter assumes an intense blue color, which 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 is slightly colored, thus showing that earth is not, so 
 powerful an agent as charcoal. Now, evidently, here the earth 
 or the charcoal have exercised a difierent influence from the filter- 
 paper alone. The filter-paper will catch suspended matter. 
 Thus muddy water passed through it may become clear, but it 
 
36 
 
 SANITARY ENGINEERING. 
 
 does not alter chemically the substance m solution. We have 
 just seen, though, that earth or charcoal does, and the usual hy- 
 pothesis to account for this fact is that ‘^porous substances con- 
 dense gases — air, oxygen, etc., in proportion to the extent of their 
 interior surface/^ and this oxygen actually destroys by slow com- 
 bustion the substance in question. The enormous amount of sur- 
 face 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 re- 
 placed when the filter is covered with water. If water is really 
 ^polluted by sewage matters, it has been shown that it may be 
 improved materially but not perfectly f)urified 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. Or- 
 ganic matter, per se, cannot always be deleterious, otherwise soup 
 would have to be ranked as poison. It is stated that the waters 
 of the Dismal Swamp, saturated with organic 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 pronounce upon the amounts that may be taken 
 into the system without injury. Chemistry can likewise deter- 
 mine 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 princij)ally, though above the 
 point where the supply is abstracted the river is contaminated 
 by the excrements of more than 200,000 human beings.’’ 
 
 Those who favor this water, claim that a polluted river puri- 
 fies itself in its ownward flow, the noxious matter being oxidized 
 as it is tossed to and fro by the current and thus rendered innoc- 
 
WATER SUPPLY. 
 
 37 
 
 nous, besides being more and more diluted. Again, fish eat 
 fresh fecal matter, and vegetation can abstract large quantities of 
 it. Still, it is doubtful if this natural 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 certain extent? 
 
 The noxious part of sewage is that which is held in mechani- 
 cal suspension, and these globules are beyond the reach of the 
 chemist, and, to a great extent, of the raicroscopist. There are 
 only two processes by which it can be etfectually 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.^’ (Humberts Water Supply, p. 19). 
 
 The organic matter is not then considered as fatal in itself, 
 but as dangerous, when of certain kinds, as atfording a refuge 
 and breeding ground for the poison germs that attend an epi- 
 demic. A person may drink even diluted sewage with but 
 slight inconvenience until this germ is once planted in it, when 
 at once 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 debilitate the sys- 
 tem, and thus render it less able to withstand epidemics. Let 
 us then follow the natural instincts and avoid polluted air and 
 water, especially 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. 
 
 Soft waters that contain oxygen oxidize the lead and then dis- 
 solve the lead oxide formed. Hard waters containing free car- 
 bonic 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, darkens softening 
 process lessens the action of water on lead. Peaty matters form 
 a sort of protecting coating on the lead pipe that is very effica- 
 
38 
 
 SANITARY ENGINEERING. 
 
 cious 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 sulphurated 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 stoneware, or galvanized 
 iron cisterns, and replace the lead pipes by wrought-iron pipes 
 with screw joints. The tin-lined lead pipe has not proved satis- 
 factory ; 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 cis- 
 terns 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 pressure of the 
 water. The cistern should be covered and ventilated. 
 
 The rain-water as it descends brings down many impurities 
 from the atmosphere, such as soot, acid fumes, oil, etc., particu- 
 larly in the manufacturing centres; besides if organic impurities 
 in the shape of dust, such as horse manure, etc., cover the roof, 
 the water is further contaminated before it reaches the cistern. 
 The character of the roof likewise, whether lead-painted, formed 
 of new shingles or decayed ones, etc., must be considered. We 
 thus see that cistern 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 sewage 
 contamination. 
 
WATER SUPPLY. 
 
 39 
 
 Nevertheless, it should be filtered before being used. This is 
 effected in various ways. One plan, when the brick cistern is 
 used, is to divide the cistern by a porous wall into two unequal 
 parts. The foul water, let into the larger divisions, filters 
 through the porous wall into the smaller division, from whence 
 it is pumped over the house. The porous 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 efficient at first, becomes clog- 
 ged up in a few mouths by solid matter, consisting, amongst 
 other things, of insects, worms, etc.; so that the filtration then is 
 rather an injury than a benefit, as chemical analysis has demon- 
 strated. The solid matters that settle at the bottom of cisterns 
 should, of course, be removed whenever 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, are nearly 
 useless after the lapse of four months, and positively 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 organic matter from 
 water.” 
 
 “The removal of mineral constituents, and the consequent 
 softening of the water, ceases in about a fortnight, but the with- 
 drawal of organic matter still continues, though, to a greatly 
 diminished extent, when the filter is much used, even after the 
 lapse of six mouths.” 
 
 “ We found that myriads of minute worms were developed in 
 the animal charcoal, and passed out with the water when the fil- 
 
40 
 
 SANITARY ENGINEERING. 
 
 ters 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 ‘^Bischop’s 
 Spongy Iron Filter is best, though the animal charcoal 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 means 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 preference 
 to blocks, though the latter gives good results. An admirable 
 filter, that may be used in any cistern, consists of a metallic ves- 
 sel with a perforated bottom, filled with animal charcoal and 
 having a pipe leading from the to[), wliich must be below the 
 level of the water in the cistern. The water of the cistern passes 
 up through the perforated bottom, then filters through the char- 
 coal and is drawn off by the pipe when it is needed. The advan- 
 tage of this arrangement is this: the suspended articles are caught 
 mostly 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 re- 
 
AVATER SUPri.Y. 
 
 41 
 
 quires frequent renevvinp^, 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 })orous 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 })urer water than can be 
 supplied by the wells and springs now used; many of them be- 
 ing, without doubt, polluted by the many impurities thrown on 
 the surface. This involves a public system of Avater supply, with 
 its attendant system of reservoirs, filter-beds, pipes, hydrants, etc. 
 In view of such contingency, it may not be out of place to men- 
 tion some of the requirements that such a system should fulfill. 
 . 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 (Rawlinson’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 capi- 
 tal. The annual working expenses of a pumping scheme may, 
 however, be greatest. Reservoirs for service distribution should 
 be covered. 
 
 If filters are used, the water should not be exposed in open 
 reservoirs and tanks after filtration. 
 
 ^Covered, to prevent the growth of vegetable organisms. 
 
42 
 
 SANITARY ENGINEERING. 
 
 Cast-iron pipes, properly varnished, should be used for street 
 mains. Lead should not be used with soft water, either in ser- 
 vice 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 Engineering 
 Inspector to the local government board, London), are valuable,.. 
 especially as they represent the best modern thought on this sub- 
 ject, 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 pressure, over the 
 entire area of a town, and into every house, cottage and tenement,, 
 and should be secured where practicable.’^ 
 
 The ‘^constant supply at high pressure” permits consumers to 
 draw water from the pipes at any time, and can be made so effi- 
 cacious in the extinction of fires as to diminish their destructive 
 effects most materially. Fire-engines are not needed with such 
 a system. It is said that in Paris, owing to the excellent organ- 
 ization of the fire department, that a destructive fire is almost 
 unknown. The intermittent supply does not offer these advan- 
 tages. 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 elevation 
 of the reservoir above the town, the Holly System^^ of main- 
 taining this high pressure in the pipes by steam power. The 
 pumping machinery is placed near the water, which is pumped 
 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 op Supply. Available Rain-fall. — In any one 
 of these systems, it is a first requisite that the source of supply 
 shall be constant and unfailing. Where a large stream is used 
 
WATER SUPPLY. 
 
 43 
 
 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 rain-falls 
 for the different seasons, in conjunction with the measured flow 
 of the streams, if any to form, at best, only an approximate esti- 
 mate 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 valley, 
 to form a reservoir, into which shall be stored all the water that 
 drains into the valley from its catchment grounds,^’ whose area 
 can be readily computed, as it is bounded generally by well defined 
 ridge lines and the embankment in question. Now the yearly rain- 
 fall in different 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 secur- 
 ing 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 impermeable 
 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 temperature lower and the drain- 
 age area smaller. 
 
 If, however, the surface of the ground is pervious^ 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. 
 
44 
 
 SANITARY ENGINEERING. 
 
 Id 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 
 evaporates 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 rela- 
 tive humidity of the atmosphere. 
 
 In England, where observations have been conducted for years 
 over many distinct catchment basins, the loss due to evaporation 
 and absorption has been found to range from nine to nineteen 
 inches per annum, and it is the practice to consider as available 
 no more than the mean fall for three consecutive dry years (which 
 is found to be, as a rule, I less than the average rain-fall), after 
 subtracting 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 1875, gave a yearly rain-fall varying 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 available 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 A 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 
 
WATER SUPPLY. 
 
 45 
 
 16 days, or ^ inch per day. The thermometer reached 115° to 
 125° in the sun every day. It is evident from the foregoing the 
 importance of early making observations in each locality for as 
 long a period as possible, in order to ascertain the ratio of the 
 ‘^available’’ to the “totaP^ rain-fall. Rankine says that this 
 ratio is about 1 for hard rocks, roof surfaces, paved streets, &c., 
 
 to for pastures, to ^ for flat cultivated country, and 0 
 for chalk. It follows that a catchment basin is best located in 
 the older formations, consisting of hard rocks, whilst wells suit 
 best the more previous and recent deposits. London is even now 
 preparing to give up the Thames water altogether and draw her 
 supply from her underlying chalk beds. 
 
 It is important to note that the most reliable method of ascer- 
 taining the available rain -fall is to measure the actual discharge 
 of streams that drain a given water-shed. Then, by comparison 
 with the total rain-fall 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 England 
 the daily amount of water used in the towns and cities varies from 
 15 ^0 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 recommended 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 waste 
 occurs in our cities, and special attention is now being directed 
 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 gal- 
 lons is a liberal allowance. Even if we assume double this, it 
 still behooves us to take every precaution to avoid waste by the 
 use of meters or otherwise; else the large yearly cost of the water 
 supply may be needlessly doubled or trebled. 
 
46 
 
 SANITARY ENGINEERING. 
 
 Reservoir Capacity. — Well, assuming, say 45 gallons, the 
 daily demand on a reservoir is made up of the 45 gallons X 
 number of population, plus the daily evaporation from the sur- 
 face 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 reservoir 
 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 rain-fall in inches for three consecutiv’^e dry 
 years. Thus, if this rain-fall is 36 inches, the reservoir should 
 contain l,000-f-6=166.7 days storage; that is, 166.7 times the 
 excess of the demand over the dry weather su[)ply. 
 
 The following table (see ^^Engineering News,’’ August 23, 
 1879) will show the great disparity between the least and great- 
 est flow of streams: 
 
 / 
 
 Name of River. 
 
 Drainage Area 
 in 
 
 FLOW IN CUB. FT. PER SQ. MILE. 
 
 
 Square miles. 
 
 Greatest Flow. 
 
 Least Flow. 
 
 Connecticut, 
 
 10,234 
 
 20.27 
 
 0.51 
 
 Merrimack, 
 
 4,136 
 
 23.40 
 
 0.53 
 
 Schuylkill, 
 
 Tyne, England, 
 
 1,800 
 
 1,100 
 
 80.23 
 
 0.21 
 
 Passaic, 
 
 981 
 
 20.33 
 
 0.23 
 
 Croton, 
 
 339 
 
 74.87 
 
 0.15 
 
 Concord, 
 
 352 
 
 12.64 
 
 0.17 
 
 Hackensack, 
 
 Sudbury, 
 
 84 
 
 76 
 
 41.60 
 
 0.33 
 
 0.05 
 
 Croton, W. Branch,. 
 
 20 
 
 54.43 
 
 0.02 
 
 These flgures show that on large drainage areas the propor- 
 tional flow is less in freshets and greater in dry seasons than on 
 small areas.” 
 
WATER SUPPLY. 
 
 47 
 
 The ^Meast flow” given above is probably the least flow on 
 any day of the dry season. If, however, our reservoir is to con- 
 tain, say 6 months^ supply, then we desire to know the least aver- 
 age flow for any six 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 J 
 inch daily, or about 5,000 cubic feet. The total daily demand 
 is thus 65,000 cubic feet, which is about 48,000 cubic feet in 
 excess of the supply from the stream ; 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 aver- 
 age 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 rain-fall 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 sufficient capacity the 
 whole of the rain-fall, minus the loss by absorption, evaporation 
 and leakage, can be utilized ; but it has not been found desirable 
 to build such huge reservoirs in actual practice, so that much of 
 the rain-fall is purposely allowed to run off. 
 
 Sources of Water Supply m N. C. — Maintei^ance of 
 Purity. — This State is abundantly supplied with unfailing 
 sources of water supply in her many rivers nnd 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 — many of them 
 fouled to inky blackness by the refuse of thousands of manufac- 
 tories — present to our own waters, teeming with fish and drink- 
 able almost everywhere. It is to be hoped that the enacting of 
 
48 
 
 SANITAEY ENGINEERING. 
 
 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. 
 England now is making a brave effort to regain the pristine 
 purity 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. 
 
 CHAPTER IV. 
 
 SEWERAGE SYSTEMS. 
 
 WATER SEWERAGE. 
 
 Then will likely follow the complex system of water sewerage, 
 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 sufficient 
 literature exists on the subject to answer the needs of practice ; 
 so that it is needless to enter into any very technical discussion 
 of it here. 
 
 Conditions that the system should fulfill. — The ob- 
 ject to be accomplished by the 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. Let it be borne in mind by any town 
 contemplating 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, 
 
WATER SEWERAGE. 
 
 49 
 
 or less, when prncticable. This is effected l)y a correct adjust- 
 ment 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 kpown formulae for the flow of water in channels. 
 
 Example. — As an illustration, take the following, from 
 “Rawlinsoifls Suggestions’^: ^‘The sewage of a town or village 
 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 the sewers must provide for not less 
 than three times this volume, if even every drop of roof and 
 surface-water can be excluded. It is more usual to assume that 
 one-half the daily quantity is discharged in from 6 to 8 hours. ^ 
 As this cannot in 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 delivering 
 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, containing 
 
 persons, corresponds to from 18.2 to 45.5 gallons per day for 
 each person, wdiich figures represent about the extremes in Eng- 
 lish 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 velocity 
 in order that so small a sewer may be self -cleansing. 
 
 As the velocity is less for the real population of 5,500, espe- 
 cially if they use less water than 1,000,000 gallons, the inclina- 
 tion 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 
 4 
 
50 
 
 SANITARY ENGINEERING. 
 
 the sewer self-cleansing, and to prevent the formation of the 
 poisonous sewer gases, whicih are always formed when the pro- 
 gress of the sewage out of the town is slow, in spite of all the 
 ventilation schemes that may be tried. 
 
 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 dis- 
 charge of 167,000 gallons (in round numbers) in 8 hours. This 
 is slightly over the discharge of 5,500 persons, allowing 30 gal- 
 lons 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 feet in 24 hours; or at the rate of 1,613 cubic feet in one 
 minute. By use of proper formulae, it is found that an egg- 
 shaped sewer, 3J by 5 feet, ruFlning full, will discharge the water 
 at a velocity of 3f 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 intercepting sewers were constructed to carry ^ 
 inch rain-fall in 24 hours, at the time of maximum flow of sew- 
 age, larger amounts being provided for by storm-water overflows. 
 
 It. is found that different 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 
 
WATER SEWERAGE. 
 
 51 
 
 .72 inch in 12 hours, did not yield more than one-tenth of it to 
 the sewers.’’ More impervious districts required the full allow- 
 ance of 1 inch in 24 hours, together with the sewage. In Dant- 
 zic, 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. 
 
 In the records of ‘^British Rain-fall” for 1880, 1881 and 
 1882, there are reported fifty -seven falls at a rate of over 1 inch 
 per hour, forty-two over IJ inch, thirty over IJ inch, eighteen 
 over 2 inches, six over 3 inches, and two over 5 inches per hour. 
 The heaviest fall reported was at the rate of 5.8 inches per hour, 
 and it continued for 30 minutes. 
 
 Very few records of the intensity of heavy falls have been 
 kept in this country, but the observations taken for a number of 
 years at Brooklyn and Providence do not indicate such heavy 
 falls as are recorded above, and it is recommended by Julius W. 
 Adams, C. E. (“ Sewers and Drains,” p. 30), to provide for car- 
 rying oflP one inch of rain falling in an hour, for greater storms 
 occur at such long intervals that the damage done would be com- 
 paratively insignificant; further, it is recommended, for large 
 areas, to consider only one-half of this, i. e., J inch, as running 
 off through the main sewers in one hour, which is equivalent to J 
 cubic foot per second discharge for every acre very nearly. 
 
 None of the very few observations made of the proportion of 
 the rain-fall reaching the outlet of the sewers in a given time 
 indicate as much as one-half the actual rain-fall, and generally 
 it is very much less, varying, of course, with the character and 
 slope of the surface on which it falls,- as well as on the fall of 
 the branch sewers, the evaporation from the surface and, the ab- 
 sorption by the soil. Of course, on a very limited paved area, 
 the whole of the rain-fall may be taken as flowing through the 
 sewers in the time of its fall, and on very large areas much less 
 than one-half can be estimated with safety. It is plain, though, 
 that storm-overflows must be provided to carry off any excess of 
 an exceptional heavy rain-fall to prevent gorging of the main 
 sewers — in fact, branch sewers may be designed to carry much 
 
52 
 
 SANITARY ENGINEERING. 
 
 more of the rain-fall than the main or intercepting sewers into 
 which they debouch, the excess (which is extremely diluted 
 sewage), flowing off through the storm-overflows to the natural 
 outlet. Often intercepting sewers, as in London, run for miles 
 out of the city, and the expense of carrying all the storm-waters 
 through a closed conduit for such distances would be something 
 enormous, so that the greater part had best be discharged into 
 the nearest water-course at certain convenient points. 
 
 Mr. Adams proposes a formula to drain the rain-fall of one 
 inch an hour, supposed to run off in two hours, which gives the 
 following diameters of circular sewers in inches (Adams’ “ Sewers 
 and Drains,” p. 62): 
 
 Acres Drained 
 
 43 
 
 75 
 
 135 
 
 308 
 
 630 
 
 1,117 
 
 A, iC 
 
 1,925 
 
 Fall 1-480 
 
 
 
 
 
 
 
 Diameter, inches 
 
 27.6 
 
 33.1 
 
 40.2 
 
 52.9 
 
 67.2 
 
 81.3 
 
 97.4 
 
 Acres Drained 
 
 50 
 
 87 
 
 155 
 
 355 
 
 735 
 
 1,318 
 
 2,225 
 
 Fall 1-240 
 
 
 
 
 
 
 Diameter, inches 
 
 25.7 
 
 31 
 
 37.5 
 
 49.5 
 
 63. 
 
 76.5 
 
 91.1 
 
 Acres Drained 
 
 63 
 
 113 
 
 203 
 
 460 
 
 950 
 
 1,692 
 
 2,875 
 
 Fall 1-160 
 
 
 
 
 
 
 
 Diameter, inches 
 
 26. 
 
 '31.5 
 
 38.3 
 
 50.4 
 
 64.2 
 
 77.8 
 
 92.8 
 
 Acres Drained 
 
 78 
 
 143 
 
 257 
 
 590 
 
 1,200 
 
 2,180 
 
 3,700 
 
 Fall 1-120 
 
 
 
 
 
 
 Diameter, inches 
 
 26.6 
 
 32.5 
 
 39.6 
 
 52.2 
 
 66.1 
 
 80.7 
 
 96.2 
 
 Acres Drained 
 
 90 
 
 165 
 
 295 
 
 670 
 
 1,385 
 
 2,486 
 
 4,225 
 
 Fall 1-80 
 
 
 
 
 
 
 Diameter, inches 
 
 26. 
 
 31.9 
 
 38.7 
 
 50.9 
 
 64.3 
 
 78.8 
 
 94. 
 
 Acres Drained 
 
 115 
 
 182 
 
 318 
 
 730 
 
 1,500 
 
 2,675 
 
 4,550 
 
 Fall 1-60 
 
 
 
 
 
 
 Diameter, inches 
 
 27. 
 
 31.4 
 
 37.8 
 
 49.9 
 
 63.5 
 
 77. 
 
 91.3 
 
 Mr. Rudolph Heriug, C. E., proposes a modification of a 
 German formula, in which the effect of the inclination of the 
 surface and total area drained is included as well as the nature 
 of the surface, but it is not necessary to give it here, as its con- 
 sideration belongs more properly to the professional. 
 
 Relative Amounts of Rain-fall and House Sewage 
 Proper. — W e have seen that a rain-fall of 1 inch per hour, to 
 
WATER SEWERAGE. 
 
 53 
 
 ran off in two hours, gives J cubic foot or 3.74 gallons per sec- 
 ond for every acre. To show its ratio to the sewage proper, take 
 50 persons to the acre, using 75 gallons of water per day — a 
 large estimate — or 3,750 gallons per 24 hours. Let us take one- 
 half of this as flowing off in 8 hours, i. e., 1,875 gallons in 8 
 hours, or 0.65 gallons per acre per second of sewage to 3.74 gal- 
 lons of storm- water, or in the ratio of 1 to 58, say. With 100 
 persons to the acre, this ratio will be as 1 to 29. When it is 
 remembered that scarcely of the water supply is human sew- 
 age, we see the very small proportion of the human sewage to 
 the total water to be carried off in times of heavy rain-falls, 
 where all of the latter is admitted to the sewers. We can like- 
 wise gain some idea of the very great decrease in the size, and 
 hence of the cost of main sewers where all storm-water is ex- 
 cluded over sewers of ^The combined system that admit storm- 
 waters. 
 
 The house drainage system is, of course, nearly the same as to 
 cost in either case, so that the difference in cost is by no means 
 in direct proportion to the size of the main sewers. 
 
 From what has been said, it is now apparent that towns or 
 cities contemplating water-sewerage have first to decide how 
 much storm-water must be admitted to the sewers, and it is ad- 
 visable for the tax-payers to form an intelligent opinion as to the 
 relative merits of the combined and the separate systems, for 
 engineers will be found in many instances to disagree as to the 
 proper system to introduce. 
 
 Combined versus Separate Systems. — By the combined 
 system is meant a net-work of sewers sufficient for the removal 
 of alf or part of the storm-waters, in addition to the sewage, 
 with inlets for its reception along the streets as well as in the 
 yards and houses. In the separate system the storm -waters are 
 either allowed to run over the surface, along natural or artificial 
 channels to the natural outlets, or a separate system of sewers is 
 designed to carry off the storm-waters alone, the sewage proper, 
 with possibly some rain-water from roofs and yards, being carried 
 in a line of pipes to any desirable outlet. 
 
54 
 
 SANITARY ENGINEERING. 
 
 The small amount of rain-water admitted from roofs and yards 
 sometimes is for the purpose of scouring out the sewers, and is 
 generally necessary to flush the sewers in time of rain-fall, unless 
 a special flush-tank is put at the head of each branch sewer, which 
 receives a small, steady stream of water from the water supply, 
 and, when full, is automatically emptied, thus driving a large 
 quantity of water suddenly through the pipes and carrying away 
 any deposits that may have occurred from too small a flow or too 
 gentle an inclination in the pipes. 
 
 A system of small pipe sewers, admitting not a (hop of rain- 
 water, and flushed automatically daily with Field’s flush-tanks, 
 and ventilated through the house soil-pipes, which are extended 
 without a trap above the roof, has been introduced with success 
 at Memphis by Mr. Geo. E. Waring; Jr., and the system is known 
 as the “ Waring system.” It is stated that “the estimated cost 
 of this system there, was only about one-tenth of that of a com- 
 plete storm- water system, as ordinarily constructed.” 
 
 It is necessarily, in first cost, the very cheapest system that 
 can be devised, besides being in the line of simplicity and further 
 placing the main details of the house drainage, from the start, 
 in the hands of the town authorities. Again, where the sewage 
 has to be carried to some distant point to be treated by filtration 
 or otherwise, before the purified effluent is allowed to go into the 
 streams, it is evident how much cheaper the comparatively small 
 sewer needed is, and how much less the cost of pumping the rel- 
 atively small amount of sewage into the settling tanks, and the 
 cost of subsequent treatment over that pertaining to the combined 
 system. 
 
 In towns, and some cities, the discharge of storm- waters oyer 
 the surface may do but little or no damage, and, in fact, is very 
 efficient as a cleansing agent; but certain localities, especially in 
 the larger cities, require storm-sewers, for the flow in the gutters 
 may become a torrent where the grades are long and steep, and 
 thus travel may be impeded very seriously, and damage done to 
 streets and cellars. 
 
WATER SEWERAGE. 
 
 65 
 
 It is urged for the separate system, in this case, that a distinct 
 set of sewers to convey away the rain-water may be put in, where 
 necessary, at a much less depth than is required for the sewers 
 proper, and that they can discharge into the nearest stream (thus 
 giving it its natural how), and can thus be made shorter than the 
 sewage conduit, which is often carried a considerable distance to 
 the outlet', Where the city is well cleaned by carting away the 
 refuse from streets and yards daily, the storm-waters will not 
 become too impure, in their course towards the stream, to seri- 
 ously contaminate it. Again, where grades are very flat, storm- 
 sewers may be needed in localities where stagnant pools of water 
 may collect, and thus prove a nuisance. In so large a place as 
 Mem[)his (60,000 inhabitants, about), there are no storm-sewers, 
 and no inconvenience has been experienced. Even in Baltimore 
 the small pipe system has been proposed, supplemented by storm- 
 sewers where the locality demands them. There is probably no 
 town in North Carolina that suffers serious inconvenience from 
 storm-waters passing over the surface — at least, over the greater 
 part of its area; so that, from this consideration alone, the com- 
 bined system could not' be insisted on for this State, with the 
 present size of the cities. And yet this one question, of the 
 proper disposal of storm-waters, is the chief argument used for 
 the use of the large sewers of the combined system. Nearly 
 every other argument i^ in favor of the small sewers of the sep- 
 arate system. 
 
 The combined sewer, even when egg-shaped, entails deposits 
 in time of droughts. The walls are covered with slime and 
 fungous growths and the thin film of sewage cannot carry for- 
 ward the filth as readily as the small pipe sewers do with the 
 same flow, especially when thoroughly flushed daily by the 
 automatic flush-tanks at the head of each branch sewer. 
 
 Therein lies the chief merit of the small pipe sewer — no stag- 
 nation and consequently no “sewer gas” of the poisonous type 
 generated from decaying filth, that often in the large sewers 
 sticks to the sides until a copious rain falls and flushes out the 
 entire sewer. 
 
56 
 
 SANITARY ENGINEERING. 
 
 Without the fiiish-tauk to clear away all obstructions, at least 
 once in 24 hours, the small pipes might be found more harmful 
 than larger ones because of the greater dilution of the contained 
 gases in the latter. 
 
 The large sewers are generally ventilated through openings 
 (man-holes) in the streets every few hundred feet, and it is 
 advisable to have them for the small sewers likewise to assist 
 in cleaning out any accidental obstruction or matter that the 
 ordinary daily flushing fails to remove. 
 
 It is, of course, an open question whether the separate sewers 
 should be mainly ventilated through the house-drains as Colonel 
 Waring proposes. With clean pipes, truly laid and daily flushed 
 full, there should be no deposit, the sewage is rapidly carried 
 out and the sewer air can be safely passed out through the house- 
 drains above the houses to be borne away by winds, provided the 
 connections to the house-drain from the closets, baths, &c., in 
 the rooms are always efficiently trapped, so that the sewer air 
 does not pass into the rooms. The system thus requires careful 
 attention. 
 
 The system recommended by the great majority of engineers 
 requires a disconnecting trap outside the house, which cuts off the 
 air from the sewers, which thus have to be entirely ventilated 
 through expensive man-holes opening at the level of the street. 
 In fact the combined sewers are probably too large to be pro- 
 perly ventilated through the house-drains. 
 
 In the separate system, as proposed by Mr. Waring, a 4-inch 
 house-drain connects with a 6-inch branch sewer, and this in turn 
 with other sewers leading towards the main outlet sewer, the 
 sizes being increased gradually to allow for running half full at 
 the time of greatest flow. The main outlet sewer at Menifdiis 
 is only 20 inches in diameter, and of course diminishes in size 
 towards its upper end. 
 
 In very large cities, combined sewers have almost invariably 
 been built, carrying ofl‘a certain part of the storm-waters, which 
 are found to cause too serious a nuisance to be left to take care 
 of ihemselves. The storm-waters flow into trapped openings at 
 
WATER SEWERAGE. 
 
 57 
 
 the corners of streets, which traps thus accumulate filth washed 
 from the streets, and have to be cleaned by hand. This mass is 
 often of an olFensive character, particularly after decom[)osition 
 sets in. 
 
 Indeed, chemical analysis shows, in large cities, that the storm- 
 waters wash away so much filth as to render the water as impure 
 as the sewage, particularly that which first enters the sewers. 
 
 There is an objection, too, against the “separate system,^’ in 
 the two sets of sewer pipes (where needed), as against one set in 
 the combined system, and this may become serious in a densely 
 populated part of a city where innumerable pipes of all kinds 
 are laid, particularly as the drainage pipes must be laid with a 
 fall. 
 
 Cost of Water Sewerage by the two methods. — To 
 give some idea of the relative cost of the two systems, we shall 
 quote some figures from a well-known engineer, Mr. O. Chanute, 
 taken from an address delivered before the St. Louis Engineers’ 
 Club and reprinted in “Engineering News” for May 3d, 1884: 
 
 “The cost of the combined system in St. Louis has been 
 |30,416 a mile. In Brooklyn, N. Y., it has been |25,600 a 
 mile, and the cleaning costs $133 a mile yearly. In Providence, 
 R. I., the first cost has been $34,550 a mile, and the cleaning 
 cost $282 per mile annually, while in Memphis the cost has been 
 $6,875 a mile, and the sewers are cleaned and repaired at a cost 
 of about $70 a mile a year.” 
 
 “ When Memphis, fever-stricken and ruined, turned to sanitary 
 engineers for advice, the sewer-builders of the combined school 
 proposed several plans, varying in cost from $800,000 to over 
 $2,225,000, depending upon the amount of storm-water to be 
 accommodated. 
 
 Mr. Waring, however, put in about 18 miles on the separate 
 system in 1880 at a cost of $137,000, and the city authorities 
 have since added about 22 miles more, at an additional cost of 
 about $138,000, thus making a total cost of $275,000 for some 
 40 miles of sewers at the close of 1883, which are said to drain 
 even more territory than was contemplated in the estimate for 
 combined sewers.” 
 
58 
 
 SANITARY ENGINEERING. 
 
 It is not pretended that the storm-waters, running over the 
 surface, have proved a nuisance at Memphis, Mr. Chanute con- 
 tinues : 
 
 ■^‘The se'parate system of Leavenworth, Kansas, now (1884) 
 approaching completion, has cost less than $10^000 a mile, or, to 
 give it in the way in which we pay our sewer assessments, it has 
 cost 44J cents a square (of 100 square feet) for the house-drain- 
 age proper, and, including the outlets, only 65J cents a square; 
 while the combined system cif Kansas City has cost to December 
 31st, 1883, some $2.10 a square.’^ 
 
 ^^Mr. Latrobe’s estimate for a separate system for Baltimore 
 also shows a cost of about $10,000 a mile.’^ 
 
 In conclusion, on this subject of the combined versus the sepa- 
 rate system, we can only say that each town must receive a spe- 
 cial study, as to its topography, damage to be feared from storm- 
 waters and final disposal of sewage before the proper system can 
 be arrived at; but it can probably be safely said that it will be 
 many years before any town in North Carolina need think of 
 incurring the extra cost of the combined system of sewers, and 
 that the separate system, with perhaps a few storm-sewers, will 
 answer all present requirements. 
 
 Sewerage of Low-lying Localities. — Mr. Waring signi- 
 ficantly remarks (Paper on ^‘The Sewering and Draining of 
 Cities), there is one point connected with the drainage of towns 
 which is not sufficiently appreciated, especially in this country — 
 that is, that it is easy and cheap to secure a deep outlet in low 
 land, and to deliver sewage at a considerable elevation for agri- 
 cultural treatment, by artificial pumping. 
 
 ^‘The average cost of pumping for water-works is about nine 
 cents per foot of elevation for each million gallons raised. On 
 this basis t\ys cost of raising the sewage of a town of 10,000 
 inhabitants, supposing every three persons of the population to 
 contribute one hundred gallons per day to the flow, would be 
 about three cents per day for each foot? of elevation.’^ 
 
 Similarly the rain-fall can be provided for in connection with 
 deep subsoil drainage in all damp or naturally overflowed local- 
 
WATER SEWERAGE. 
 
 59 
 
 ities, as New Orleans. In fact, wherever delivering the sewage 
 into the stream or body of water near at hand means contamina- 
 tion of the town, pumping will have to be resorted to. Boston 
 has secured deep drainage by such means and in addition re- 
 moves her sewage to such a distance that the return tide does not 
 bring it back to the city. 
 
 Subsoil Drainage. — If there is but one sewer system, then 
 the subsoil must be drained by small pipes, simply butted to- 
 gether at the ends, so that the subsoil water can enter. The pipes 
 must be placed on top of the sewer pipe to prevent any infiltra- 
 tion from the sewer, which often happens if they are placed 
 below the sewer. This subsoil drainage 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 saturates it 
 with the vilest poison, that invariably produces harm as soon as 
 it can find an outlet to the 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 af 
 greater inclinations than cause a velocity of six feet per second, 
 if possible, to avoid the cutting out of the bottom of the sewer 
 by grit and other solids. The location of the main outlet sewer 
 determines, to a great extent, the positions of the other sewers, 
 and should receive special study. House-drains are generally 
 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 decomposition which occurs in close places having 
 a limited amount of air. 
 
 ‘Hn fully ventilated sewers, the sewer air is generally purer 
 than that of some stables, or even in a crowded public room.^^ 
 
60 
 
 SANITARY ENGINEERING. 
 
 It is always advisable to place the man-holes at each curve or 
 change of grade of the sewers, so that one can see down the sew- 
 ers from man-hole to man-hole, especially for small sewers, where 
 scrapers have to be pulled through to clear away any deposits. 
 
 House-drainage. — The proper* treatment of this subject, 
 like some others that have only been briefly touched upon, would 
 require a volume in itself, at least to consider all the various 
 designs and fixtures that have been proposed ; but the essential 
 elements of house-drainage can be gained from a consideration 
 of the subjoined diagram, taken by permission of the publisher 
 (D. Van Nostrand, N. Y.), from the excellent little manual by 
 Wm. Paul Gerhard, civil sanitary engineer, entitled ^‘House- 
 drainage and Sanitary Plumbing,’’ to which the reader is 
 referred for further information. 
 
 The figure represents a section through a dwelling-house, in 
 which C is the 4-inch house-drain connecting with the sewer (not 
 shown) that carries ofi‘ all wastes and liquids from the house. 
 
 D is the running-trap on the main drain to' disconnect the 
 house from the sewer. 
 
 In the ^‘Waring system ” this trap is left out, so that the house- 
 drain extended as shown, full fore, above the roof, serves to ven- 
 tilate the sewers, reliance being placed entirely in the traps to 
 room fixtures to exclude the sewer air from the rooms. In Eng- 
 lish practice it is recommended to have two such traps as that 
 shown at D outside the house with an open gulley between them, 
 to permit the discharge of sewer air if the first trap is forced 
 from too great back pressure in the sewer, as well as for pur- 
 poses of cleaning. 
 
 Such open traps are liable to freezing in Northern latitude, but 
 are advisable in our Southern States, as being an additional secu- 
 rity against the admission of sewer air. Their use necessarily 
 entails the ventilation of the sewers through man-holes. The 
 Waring plan is simpler and cheaper, and it would seem that if 
 experience shows that the sewer air, from the daily flushing, 
 remains purer than that of the house-drains, and that obstruc- 
 tions are quickly got rid of, that the plan is to be recommended 
 for the small pipe sewers*. 
 
WATER SEWERAGE. 
 
 61 
 
 p] is a V branch closed with a screw for cleaning. F is the 
 fresh air pipe, to permit of a constant circulation of air in the 
 house-drain inside of the house, to oxidize the foul organic mat- 
 ter clinging to the pipes. The current is generally from the 
 fresh air inlet up, through the roof, as the house-pipe is warmer 
 as a rule, except perhaps some days in summer. 
 
 Another reason in favor of this fresh air inlet, when the drain 
 has been trapped outside ^the house, is that without it, water dis- 
 charged through any fixture into the house-drain, forces a certain 
 amount of air before it which may, in turn, force some trap and 
 thus send a puff of sewer air into the living-rooms. 
 
 In the Waring system this fresh air inlet is left out. 
 
 It is evident that if the house-drain discharges into a cess-pool 
 or flush-tank, that the trap D and inlet F should not be omitted. 
 
 G is the 4-inch house-drain, laid with a fall and supported 
 from the ground to prevent settling and opening of the joints. 
 H H are the 4-inch soil pipes, protected at top by wire-baskets. 
 Both G and H should be of cast-iron with well caulked lead 
 joints. The other pipes are often of lead, though in the system 
 carried out by the Durham House-drainage Company, all pipes 
 are of wrought-iron, with special screw joints that are perfectly 
 light. Such a system is supported from the ground, so that it is 
 not liable to open joints from settlement of walls or floors, the 
 pipes being of sufficient strength to withstand the strain. As a 
 fact, cast-iron pipe is not of uniform thickness or strength, whilst 
 lap-welded wrought-iron pipe can be so obtained, so that this 
 Durham system is to be regarded as superior to the ordinary 
 method of plumbing, particularly where much lead pipe is used; 
 for lead is liable to sag and split open, to be corroded by sewer 
 gas on the upper side, to have nails driven into it ; and, to be 
 eaten into by rats. Still lead is almost universally used for con- 
 nections and is generally satisfactory. 
 
 J is a refrigerator; K, a water-tank supplied from the street 
 pressure. Its overflow-pipe L is trapped by an S trap with deep 
 seal, and emptying into the gutter of the roof. The blow-off 
 from tank delivers over the kitchen sink. 
 
62 
 
 SANITARY ENGINEERING. 
 
 M M are small cisterns for flushing the water-closets and slop- 
 hopper only. Where fixtures are flushed by pipes from the street 
 pressure, it sometimes happens that if a lower cock is opened,, 
 that the upper cock (which we suppose open too) will, for the 
 time, cease to flow and in fact suck ^n the air of the fixture into 
 the water-supply, thus poisoning all the drinking water. 
 
 O O are wash-bowls with IJ-inch waste-pipes and overflow- 
 pipes of lead, trapped by anti-siphoning or mechanical traps, and 
 delivering into 4x 2 Y branches of the soil-pipes. 
 
 P is a pantry sink, trapped as above. 
 
 Q are slate, cement stone, soapstone, or ceramic wash-tubs, 
 with IJ-inch waste-pipe, trapped as before. 
 
 T is a bath-tub, of enameled iron or heavy planished copper, 
 or of porcelain. It is provided with a standing-waste and trap- 
 ped by a mechanical trap. 
 
 T' is a hip-bath, trapped by a vented S trap. 
 
 V is a 2-inch air-pipe to prevent the siphonage of the water- 
 closet traps. 
 
 It is seen, from the figure, that vent-pipes from the top-bend 
 of traps enter this pipe V, thus tending to prevent any siphon- 
 age action in such bends. 
 
 It is enlarged to 4 inches through the roof. The water-closet 
 trap at the right of the bath-tub is not shown with a vent, be- 
 cause the water-closet is of the improved short hopper type^ hold- 
 ing water to the depth of six inches in the bowl, which seal 
 could never be broken by siphonage or capillary attraction.’’ 
 
 Siphonage may occur in traps with small depth of seal, by the 
 momentum of the flushing water suddenly discharged into the 
 trap, filling the upper bend and thus starting a siphon action, 
 which nearly empties the trap and allows sewer air to enter. The 
 seal may be broken by siphonage likewise, by the discharge of a 
 large quantity of water into some other fixture connecting with 
 the same soil-pipe, from the tendency to create a partial vacuum ; 
 particularly if the second fixture discharges through the same 
 pipe, into the soil-pipe, as the first, a method to be avoided if 
 possible. 
 

 WATER SEWERAGE. 
 
 63 
 
64 
 
 SANITARY ENGINEERING. 
 
 The vent-pipes mentioned are generally as afegnard against 
 siphonage from the causes enumerated, though they cause in- 
 creased evaporation from water-seals, and thus prove a draw- 
 back when fixtures are unused for some time. 
 
 In fact, it is absolutely necessary to run water into fixtures 
 periodically to prevent sewer air from entering rooms, particu- 
 larly when unused and unventilated. 
 
 The soil-pi {)es H H extended through the roof and open at 
 top effectually prevent traps being forced by back pressure from 
 the sewers. 
 
 In addition to the loss of water-seal through siphonage, eva- 
 poration and back pressure, capillary attraction may be added; 
 for if threads or hairs extend from the water in the trap over 
 the bend, the water may be drawm off* along the filaments by 
 capillary attraction. 
 
 A deep seal is a protection against all the causes named, though 
 nothing can take the place of continual supervision. Eternal 
 vigilance alone is the price of health. It must be borne in mind 
 too, that the water in traps absorbs sewer-gas and passes some of 
 its constituents into the room. It is true that the amount is very 
 small and considered harmless, for experiment seems to indicate 
 that germs, even if contained in the water of traps, are not libe- 
 rated from it, as was hitherto supposed, unless the water is vio- 
 lently agitated’’; still it is in every way desirable and on the side 
 of safety to change the water of traps every few days, and keep 
 down any slight odor that might arise, so that the air of rooms 
 is always sweet and pure. 
 
 The water-closets, in the figure, W W W, are of the long and 
 short hopper and washout kinels, without any mechanical device 
 (as in the pan, valve and plunger closets) to get out of order and 
 become foul. It is true that these closets become foul at times, 
 but then they can be readily cleaned, which cannot be said of the 
 mechanical closets, whose foul [)arts are not so easily got at. The 
 above closets are flushed from the special cisterns M M M. 
 
 X X is the rain-leader delivering the water into the running- 
 trap of the house-drain. 
 
WATER SEWERAGE. 
 
 65 
 
 Y is the blow-off' from the boiler, which wastes into a Y 
 branch of the iron drain in the cellar. 
 
 Drainage of the Foundation. — The subsoil- water below 
 the house is kept at a certain depth by laying small IJ-'ach tiles 
 inside of the foundation walls to a little more than tiie required 
 depth, say 2 or 3 feet, d'hese pipes connect with the joain drain, 
 B in the figure, which discharges into a gravel-trap A, with a 
 water-seal to prevent sewer-gas from entering the drain tiles and 
 thus poisoning the ground under the house, in case a connection is 
 made with the sewer. For the same reason the outlet pipe from 
 the trap A should bend downwards into the water. Often this 
 trap is made of large pipe which extends vertically up to the 
 surface, and is protected by a grading, in order that the water-seal 
 may be periodically inspected and cleaned. 
 
 The best practice is to lay subsoil (trains along side the sewers 
 into which drains like B discharge directly without the interven- 
 tion of a trap, as no sewer-gas need then be feared. 
 
 The tile drains are laid with open joints, around which tarred 
 paper or cloth may be WTapped to prevent the entrance of dirt. 
 
 In a country house fhe trap A is not needed, as the drain can 
 generally be made to discharge at the surface at some lower level 
 than the house is situated on. 
 
 In such case the mouth of the drain should be protected from 
 wash by a foundation of stones properly laid and a grating of 
 iron or earthenware should be placed in the mouth to prevent 
 vermin from entering and obstructing the drain by building 
 nests within -it. 
 
 The roots of trees often enter drains through open joints and 
 choke them up. Cementing the joints near the trees with 
 asphalt must then be resorted to or the tree must be cut down. 
 
 In place of the tile drains mentioned, broken stone thrown to 
 the bottom of the trench to a certain depth and covered up with 
 earth, also box drains of wood, and pole drains, may be more 
 cheaply constructed, but they cannot be regarded as at all per- 
 manent, as the broken stone drains finally fill up with earth and 
 the wooden drains decay after a number of years. 
 
 5 
 
66 
 
 SANITARY ENGINEERINa. 
 
 Dampness of wares and cellars. — To prevent daaipness 
 of walls and cellars below the ground-level an imj)ervious or 
 ^^damp course must be used. 
 
 For cellars a layer of asphalt J inch thick on top of the con- 
 crete floor, covered by a layer of cement, is found to be very effi- 
 cacious. This layer of asphalt should be continued through the 
 walls and extended upwards on the outside to the ground-level 
 to completely shut off dampness in the foundation walls. 
 
 A horizontal layer of slate in concrete is often laid in the walls 
 at the ground-level and effectually cuts off dampness from below. 
 
 The space immediately around the walls should be filled with 
 broken stone and the footing course of the walls may rest upon 
 broken stone, if the foundation is good, otherwise upon concrete, 
 especially in the case of large buildings. 
 
 Double walls, with an air-space between, are likewise used to 
 prevent dampness whether from the soil or the atmosphere. 
 
 By the proper drainage of the subsoil and the use of damp 
 courses all through the foundations, we not only ensure dryness 
 — a very important thing to health — but also prevent the en- 
 trance of sewer-air or poisonous gases thrown off by decompos- 
 ing animal or vegetable matter in the subsoil, often carelessly 
 placed against the walls. Prof. Renk finds ‘Hhat the draught 
 or current is from the ground into the house for the greater part 
 of' the year and that it brings with it particles of whatever 
 injurious matter the soil may contain.^’ ^^This ground-air is 
 kept in continual movement by the state of the winds and the 
 atmosphere.’’ 
 
 For further information on this subject of foundations, see a 
 recent publication, ‘‘Healthy Foundations for Houses,” by 
 Glenn Brown, D. Van Nostrand, N. Y., publisher. 
 
 Cess-pools. — rin cities where water sewerage has not yet been 
 introduced, the abomination called the cess-pool is used to receive 
 the filth of the houses. These cess-pools are of two kinds, the 
 leaching and the tight cess-pools. Both are receptacles built of 
 brick, say of 5 to 10 feet diameter and 5 or 6 feet high and 
 dome-shaped, surrounded with earth, with the soil-pipe entering 
 
WATER SEWERAGE. 
 
 67 
 
 OD the side, and preferably, with two ventilating pipesextending 
 from the top of the dome and near the sewer entrance respect- 
 ively, some 10 feet above ground to carry off impure gases by 
 the current induced and to prevent undue pressure in the cess- 
 pool from the gases formed. In the leaching cess-pool the brick- 
 walls are {)orous, so that the sewage can soak through them into 
 the ground, where it remains to poison the ground-water or to 
 decompose and gradually find its way to the surface as gas, where 
 a healthier decomposition may render it harmless. 
 
 Nothing can he worse than this poisoning of the ground if 
 water is taken from wells in the vicinity, for sooner or later, the 
 sewage must reach them; besides, the ground-air around and 
 under a house should be as pure as possible, for it is the air we 
 breathe; lasily, the leaching cess-pool permanently pollutes the 
 soil, no matter if a better system is ultimately introduced, and 
 thus digging new trenches or foundations in such a soil must be 
 attended with deleterious consequences. 
 
 The absolutely tight cess-pool, with cemented walls, is a great 
 improvement over the leaching cess-pool, and it must be regarded 
 as only a temporary receptacle for filth, which is to be pumped 
 out and removed outside the city limits periodically. 
 
 The suction-pipe can be let down through a hole in the dome, 
 left for that purpose, and which is ordinarily covered with a slab. 
 
 The tight cess-pool is too often so badly made as to prove a 
 leaching cess-pool ; besides, its ventilation is generally neglected, 
 so that sickening gases issue from it on opening, and sometimes 
 storm-waters may cause it to overflow back into the house, unless 
 it is carefully attended to. 
 
 These cess-pools, when they have to be used, should be located 
 at least 50 or 60 feet from the house, in fact as far away as prac- 
 ticable. They should only be tolerated as a necessary, though 
 temporary nuisance, for use in towns where water sewerage can- 
 not be afforded, a system whose main purpose is to remove, as 
 rapidly as possible, all filth outside the city limits, as opposed to 
 the system of storing up this filth in cess-pools or in the ground 
 for indefinite periods, thus vitiating both the soil and the atmos- 
 phere. 
 
68 
 
 SANITAEY ENGINEERING. 
 
 Disposition of Sewage. — Having briefly considered some 
 points of general interest in connection with the design of sewer- 
 age works, let us next enquire what is to be done with the sew- 
 age. 
 
 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 any- 
 thing but an air of cleanliness to the eye, or of satisfaction 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 dis- 
 posed of by precipitation, treatment with chemicals, and partial 
 land -filtration. There are 24 towns, &c., whose sewage is dis- 
 posed 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 carried by the outlet sewer to the “sewer- 
 farm,^^ where, if necessary, 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 filtration through a porous soil. 
 
 This j)lan might be carried out for small towns 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 surrounding soil, which 
 purifies it by absorption and oxidation. A chea[)er method for 
 cities consists in simply passing the fluid sewage on to ground 
 deeply drained. The purified water runs ofi* in the drains, and 
 thence into the streams. 
 
watp:r sp:wp:rage. 
 
 69 
 
 By distributing' the sewage over a suflficieni extent of surface, 
 it is found that the soil does its work perfectly; being aided, 
 moreover, by the growing vegetation, taking up much of the sew- 
 age through its roots. The purification, though, is principally 
 due to the earth, which has the property of absorbing and con- 
 densing gases, such as air, &c.; so that each little [)article 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 olf some of it into the air — not as 
 poisonous effluvia, 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 re- 
 placed as rapidly as it enters into combination, and thus to fur- 
 nish 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 sub- 
 stances are not simply absorbed (as usually stated) by the earth or 
 charcoal, or other porous material ; but are chemically changed 
 — oxidized or burnt up — so that their objectionable features are 
 no longer perceived; the nitrogen, etc., is thrown off into 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 analy- 
 zed 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. War- 
 ing, Jr. (see ^‘The Sanitary Condition of Dwelling 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 
 from a flush-tank through loosely-jointed pipes, laid about one 
 
70 
 
 SANITARY ENGINEERING. 
 
 foot below the surface in the back yard. He states that the sys- 
 tem 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 pro- 
 fitable, unless in .the way of irrigation. Fine crops have been 
 raised on such sewage farms; so that where intermittent filtra- 
 tion 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 
 C) 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 diffi- 
 culty .of manipulating the accumulations of sewage sludge both 
 make against it; still much of this sludge must be removed in 
 some way before filtration 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 distance 
 as not to be brought back to the town by wind, tides 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 in his designs. 
 
 THE LIEURNUR 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 disagree- 
 able odors, and carrying off the matter in short periods, are 
 almost entirely fulfilled in Lieurnur’s Pneumatic Sewerage sys- 
 tem, 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 
 
THE KOCllPH)ALE SYSTEM. 
 
 71 
 
 central station, where the air-piiinp is placed which pumps all 
 the matter into a reservoir. The collection and sale of this mat- 
 ter does not usually cover the cost of the labor. The reports on 
 this system are conflicting, and yet the majority of them speak 
 in its favor.^’ 
 
 Mr. C. Norman Bazalgette, in a late |>aper 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 car- 
 riage system, extremely costly, and its mechanism w^as extremely 
 complicated and liable to get out of order. The accumulation of 
 sewage residium in the central reservoir, and its subsequent 
 decanting into barrels, W'ere operations which could not fail to 
 be objectionable and offensive. In conclusion, the system — 
 though it might have a partial j)rovince in the tide-locked cities 
 of the Hague, where no system of sew^erage was available — 
 should never be imported 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 ROCHEDALE PAIL SYSTEM.* 
 
 This consists simply in half-barrels or pails being placed under 
 the seats of the closed privy to receive the fecal discharges; the 
 pails being removed about once a week, after putting on a her- 
 metically-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 covering of dry earth being used to 
 keep down the smell, or the matter may be 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. 
 
 *See Appendix II, page 79. 
 
72 
 
 SANITARY ENGINEERING. 
 
 All of our cities and towns can introduce this system with 
 such a small outlay of capital, that it would seem to be the one 
 just now to be most highly recommended for many towns. 
 
 The corporation should bear the expenses of the transporta- 
 tion of the excrementitious matter, as well as of other refuse and 
 filth found in all towns, due to various causes. 
 
 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 fiy^m and dry plank or concrete foundation.'^ The only dif- 
 ference 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^ 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 clbsets are used, two small cart loads 
 of garden earth, dried and sifted. This was used repeatedly in 
 the closets, and when an increased quantity was required, addi- 
 tions were made of sifted anthracite ashes. The amount of 
 material m)w on hand is about two tons, which is ample to fur- 
 nish a supply of dry and decomposed material whenever it be- 
 comes necessary to fill the reservoirs of the closets. The accumu- 
 lation 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 keej) down any odor that might 
 arise. After a sufficient interval these heaps are ready lor further 
 
 *See Appendix II, pages 78 and 79. 
 
THE DEV EARTH SYSTEM. 
 
 73 
 
 use, there l)eii)g 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 has been used over 
 and over again, at least ten times, and there is no indication to 
 the sense* of any change in its condition.’’ 
 
 The same earth can be used over and over again, thus doing 
 away with what was once urged as the principle objection to the 
 earth-closet system — the continual removal of large bodies of 
 earth. 
 
 A chemical analysis showed that there was no more organic 
 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 [iroperties 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., have all been success- 
 fully 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 toAvn of what 
 has hitherto been its n)ost troublesome product, 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 organic 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 sufficient 
 amount of fertilizing matter to make it an available commercial 
 
 manure.' 
 
74 
 
 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 organic elements 
 back again, uncombined, or at least in harmless combinations, to 
 the air; and this the condensed oxygen accomplishes. 
 
 One advantage of the system is that the privy or commode,’^ 
 may be attached to the house; in fact the best earth-closets may 
 be kept in the chamber, without any other odor being perceived 
 than that of the earth used, which should be fine, dry and sifted. 
 
 This dry-earth system is familiar to soldiers of the late war, 
 the sinks used by them receiving daily a slight covering 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 system was carried out faithfully — 
 that the earth was uot worth removal as manure. This fact I 
 know from experience; and it agrees with all other experiments 
 and analyses referring 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 hesita- 
 tion in the choice. • ' 
 
 Where the dwelling {)l;ice 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 chem- 
 ical changes effected may have liberated potash or soda, etc., in 
 the original soil, thus rendering it more valuable than before to 
 plants. 
 
 It may be interesting to know that there is biblical sanction 
 for this method; the Israelites being required to carry out the 
 system whenever they went outside of the camp to ease them- 
 selves. (Deut., xxiii: 13). 
 
 It is admitted that this system does uot admit of the same 
 public control as the preceding, but it may be made eminently 
 serviceable by those who desire it. It is especially applicable to 
 country houses and the smaller villages. 
 
CONCLUSIONS. 
 
 75 
 
 I know of this .system being carried out and satisfying tlie 
 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 some use as a fertilizer. 
 
 When epidemics prevail, then in addition to usual methods 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 can- 
 not but be impressed with the beneficence of those laws that tend, 
 in one eternal round, to the purification of what man has made 
 unclean. Foul sewage is thrown into a crystal stream, whose 
 hitherto transparent waters now blush at the pollution. She 
 invokes the aid of the ever-constant winds and of the animal and 
 vegetable life she bears in her bosom. They respond, and, in 
 time, she is once more pure and undefiled. The pure Avater falls 
 from clouds, cleanses our soil and passes into the earth, foul, 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 on the means 
 that have been proposed to assist nature in her work of purifica- 
 tion and act on them. 
 
 It is not intended that the foregoing brief summary of 
 ‘‘means” is complete. It was not intended to be, though funda- 
 mental general principles, proper to be known at present, it is 
 hoped have been stated clearly and fairly. 
 
76 
 
 SANITARY ENGINEERING. 
 
 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 espe- 
 cially 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 some of the systems for the disposal of sewage matters be 
 faithfully carried out simultaneously with a proper attention to 
 ventilation, drainage, water supply, and the general 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 contamination of 
 the wells will be gone, and that zymotic diseases will have their 
 usual channels of attack effectually cut off. 
 
 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 neces- 
 sity, to be enforced in city and village by stringent laws and 
 requirements. 
 
APPENDIX I. 
 
 \ The following table may prove a convenience to those who use 
 cisterns. It gives the capacity of a cylindrical cistern, 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. 
 
 Feet. 
 
 Capacity. 
 
 Gallons. 
 
 Diameter. 
 
 Feet. 
 
 Capacity. 
 
 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 
 
 11 
 
 711 
 
 21 
 
 2591 
 
 12 
 
 846 
 
 22 
 
 2843 
 
 13 
 
 993 
 
 23 
 
 3108 
 
 14 
 
 1151 
 
 24 
 
 3384 
 
 Multiply these tabular numbers by the height of the cistern in 
 feet to get the capacity of a cistern corresponding to that height. 
 
APPENDIX II. 
 
 Through the courtesy of Dr. Charles F. Folsom, of the Mas- 
 sachusetts Board of Health, the accompanying wood-cuts are pre- 
 sented — they having first appeared in the Massachusetts 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; sec- 
 tions of common privies and sink-hole, both polluting the soil 
 around them; and lastly, three plans for privies based upon the 
 dry-earth system. 
 
 It is to be observed with respect to the latter, that the con- 
 ditions are simply that the pails used be completely under 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 effluvia 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 being an 
 apartment just to the rear of the pails, from which it can be 
 readily shovelled into the pails under and not th7'ough 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, nearly as 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 figures. On open- 
 ing this door, the half-barrels or pails can be set under the seats, 
 and every morning charcoal, etc., can be thrown over the con- 
 tents 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 inches' above the ground, so that water 
 may not reach them. As the pails are filled they should be 
 
APPENDIX II. 
 
 79 
 
 emptied under a shed and dry earth, etc., strewn over the con- 
 tents, 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 cov- 
 ering of earth being again used to keep down any odor that 
 might arise. 
 
 It must be borne in mind, however, that although soil is an 
 excellent filter for impure or infected air, that may pass through 
 it, it is a very poor filter for infected water from privies, cess- 
 pools and sewers, so that danger of contamination of wells from 
 these sources, particularly when deep down in the earth, away 
 from its oxidizing tendencies, needs always to be carefully 
 guarded against. Such filth-soaked soils may take ages to 
 purify and afford good drinking water. 
 
80 
 
 APPENDIX II. 
 
• jio^ crpTL ^njj. J.0 Snpi. 
 
 APPENDIX II. 
 
 81 
 
82 , 
 
 APPENDIX II. 
 
 Manchester CorporcdiotL, 
 
APPENDIX II. 
 
 83 
 
84 
 
 APPENDIX II. 
 
 Rochdale Corporation 
 Paitera Fail closet. 
 
 td. excremerLt pail, 
 
 Fash iuJb. 
 
 G. scaicoym {raised) 
 
 D iron collar helorir seat .reackinsr sh^ly into 
 pail rdie2i corer is doryn. 
 
 F, hinyed upright of seat 
 
 CdDOvadmiiim^ftom-Ovisidc toexcrcmcht pail 
 
APPENDIX III. 
 
 The following lucid description of the ventilation of the State 
 Lunatic Asylum of New York, located at Utica, New York, is 
 taken, by permission of its author. Dr. John 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 ventila- 
 tion of the institution to be the safest, most economical, and best. 
 Information is frequently sought as to the system adopted. Re- 
 cently an application made through the State Department by the 
 British government for a detailed statement concerning the appli- 
 ances and method, was referred to Dr. Gray, the superintendent 
 of this institution, who made a report which was submitted to 
 this board before transmission. The managers deem it such a 
 clear and succinct statement of the method adopted, that they 
 embody it as a document worthy of permanent record for use 
 and reference. 
 
 MODE OF VENTILATING AND HEATING. 
 
 1. The mode of ventilation adopted is that of forcing air into 
 the building by the use of two centrifugal fans, a drawing and 
 description of which accompany this communication. 
 
 2. The air is delivered from the fans to all parts of the build- 
 ing. 
 
 3. First: Into the large channel or basement air duct, or air 
 plenum, which is continuous under the whole building. 
 
 4. Second : From this air duct or air plenum, the air passes 
 by flues into the various wards and rooms to be supplied. Each 
 flue is independent; that is, it has an exit at but one point. 
 
86 
 
 APPENDIX III. 
 
 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 windovs^ or door will 
 disturb the current of the incoming air. The air is thus dis- 
 tributed uniformly through every part of the building. 
 
 5. From the corridors and rooms flues are constructed, start- 
 ing just above the base-board, each flue passing independently 
 into the attic air-chamber. Over part of the building there 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 contain 
 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 occupant. 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 the 
 area of the several flues 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 
 frotn the corridors at or near the floor. 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- HTur inches area. In some the air enters the sleeping- rooms 
 through a register in the bottom rail of the door. In the asso- 
 ciate sleeping-rooms, where sufficient air could not thus be ob- 
 tained 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. 
 
APPENDIX III. 
 
 87 
 
 9. This mode secures the most abundant supply of fresh air. 
 It secures what ventilation means practically: that is, such con- 
 stant 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 ‘Afresh 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 enlarge- 
 ment of the areas facilities 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 introduced at 
 a height above the doors and windows. While this is undoubt- 
 edly best, it is not absolutely necessary to success in ventilation. 
 It is proper to say that in a hospital for the insane, it is advisa- 
 ble 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. 
 
 12. Where the rooms are large, as in case of parlors and sit- 
 ting-rooms, and require two or more flues for the introduction 
 and exit of air, it is important to distribute them so that all 
 parts of the rooms shall be supplied uniformly. 
 
 13. Heating is combined with ventilation. The air is warmed 
 to the degree required by being compelled to pass over cast-iron 
 raditors, through which steam is circulated, on its way from the 
 fan to the occupied parts of the building. 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 occu- 
 pied parts of the building. There is a box of radiators for each 
 
88 
 
 APPENDIX III. 
 
 set of three flues, one flue leading to each story. Each block 
 has an independent connection with the main steam-pipe, so that 
 each block can be used separately. Each block is cased in on 
 the sides, leaving the bottom open for the free passage of air 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 into any special part of the build- 
 ing can be regulated as may be desired, simply by introducing 
 more or less steam into the individual blocks. 
 
 14. These radiators are so constructed and connected as to 
 make what is called a steam coil,^^ and the blocks are so 
 arranged and connected that steam can be turned upon one-third, 
 two- thirds, or the whole, as the atmospheric temperature may 
 require. Of course, 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 pas- 
 sage of the largest volume of air required. 
 
 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 introduced 
 higher than 100 degrees at the point of entrance to the wards 
 and rooms, in order to secure a general temperature 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 to control the tempe- 
 rature of the room by closing and unclosing them. The amount 
 of air delivered over each radiating block is warmed to the tem- 
 perature there required, and as the volume of the air delivered 
 is uniform and constant, thorough ventilation is obtained. Reg- 
 isters in the wards of a hospital 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 information to the engineer having control of 
 the heating blocks. Registers are used in the offices and resi- 
 dences of the officers. 
 
APPENDIX III. 
 
 89 
 
 17. It is possible to determine the exact amount of coal neces- 
 sary 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 tempera- 
 ture of the external atmosphere, and knowing the volume of air 
 delivered, can, with sufficient 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 average outside tempera- 
 ture 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 ; 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 diameter. The shaft extends beyond the casing and 
 rests on pulley-blocks, and on the driving side it is lengthened 
 six feet to receive the driving-pulley and remove all obstruc- 
 tion to the easy entrance of air to the fans; the motion 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 circumference of which 
 instead of being concentric with the shaft, describes a curve of 
 increasing diameter and forms outside the wind-boards a chan- 
 nel of constantly enlarging capacity towards the point of delivery. 
 
90 
 
 APPENDIX III. 
 
 The casing is therefore 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 oh 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. 
 
 THE LIBRARY OF THE 
 
 NOV 11 1938 
 
 UNIVERSITY OF ILLINOIS- 
 
UNIVERSITY OF ILUNOI8-URBANA 
 
 3 0112 049890053