TH 7222 .K65 Book._^il4iL_ CojpgMN?. COFVRICHT DEPOSIK VENTILATION FOR DWELLINGS, RURAL SCHOOLS AND STABLES BY F. H. KING Formerly Professor of Agricultural Physics in the University of Wis- consin. Author of ' ' The Soil; ' ' ' 'Irrigation and Drainage; ' ' ' 'Physics of Agriculture. ' ' * • • MADISON. WIS. Published by th( g Author 1908 LIBRARY cf CONGRESS Two Copies Received DEC 18 1908 Copyriifot tntr euss flu xXt^Mo, ■LZ7.5Z.0 COPY a. "Copyright, 1908 byf. h. king. All rights reserved- V>3 PHYSICS OF AGRICULTURE By F. H. KING Professor of Agricultural Physics in the University of Wisconsin, 1888-1901 ; Chief of the Division of Soil Management, U. S. Department of Agricul- ture. 1901-1904. Author of "The Soil." 1895 ; "Irrigation and Drainage," 1899 : "Tillage, Its Philosophy and Practice," "The Necessity and Practice of Drainage," in Cyclopedia of American Agriculture, 1907 ; "Drainage" and "Irrigation," in The Standard Cyclopedia of Modem Agriculture, (British), 1908. Fourth Edition, 604 pages, 7%x5% inches, 176 illustratio'ns. Published by the author, Madison, Wis. Price $1.75 CONTENTS Ihtroduction 6- 48 SOIL PHYSICS Nature, Origin and Waste of Soils 49- 68 Chemical and Mineral Nature of Soils . 69- 91 Soluble Salts in Field Soils 92-107 Physical Nature of Soils 108-128 Soil Moisture 129-141 Physics of Plant Breathing and Root Action 142-157 Movements of Soil Moisture 158-203 Relation of Air to Soil 204-211 Soil Temperature 212-222 Objects, Methods and Implements of Tillage 223-254 GROUND WATER, WELLS AND FARM DRAINAGE Movements of Ground Water 255-274 Farm Wells 275-285 Principles of Farm Drainage 286-310 Practice of Underdrainage 311-328 PRINCIPLES OF RURAL ARCHITECTURE Strength of Materials 329-342 Warmth, Light and Ventilation 34.3-365 Principles of Construction 366-393 Construction of Silos 394-427 FARM MECHANICS Principles of Draft 428-443 Construction and Maintenance of Country Roads 444-485 Farm Motors 486-537 Farm Machinery 538-553 PRINCIPLES OF WEATHER FORECASTING The Atmosphere 554-560 Movements of the Atmosphere 561-577 Weather Changes 578-592 "All in all, this is the greatest and best collection of modem agricultural scientific facts, practically applied, that we have seen. Anyone, whether he be a farmer 6v not or whether he be a student in a college or an old man in the field, can learn a great deal here. It is a mine of correct information. We shall value it highly as a work of reference." — Ohio Farmer, March 27, 1902. CONTENTS INTRODUCTION (pages 1-44) PAGES Nature's Provision for VsNTiiiATioN of Body Tissues 3- 8 Amount of Air Required for a Daily Ration 8- U Air Once Breathed has Lost Much of its Sustaining Power 11-17 A Continuous Flow of Air is Necessary 17- 19 Fresh Air Supply certain to be Inadequate at Times if Definite Provision for it is not Made 19- 24 Serious Effects Follow Insufficient Ventilation 24-31 Volume of Air Which Should Move Continuously through DWELINGS AND StABLBS 31- 45 PRINCIPLES OF VENTILATION (pages 45-75) Power Used in Ventilation 46- 64 Maintenance of Temperature with Ample Ventilation 64-75 PRACTICE OF VENTILATION (pagres 76-126) Best Room and Stable Temperature 76- 78 Light for Dwellings and Stables 78- 88 Ventilation of Dwellings 88-102 Ventilation of Houses Already Built 90- 94 Warming- and Ventilation of New and Remodeled Houses 94-102 Heating and Ventilation of Rural School-houses and Churohes102-106 Stable Ventilation 107-126 Ventilation of Dairy Stables 109-120 Ventilation for Swine and Sheep 120-123 Ventilation of Poultry Houses 123-126 PREFACE In the preparation of this brief treatise the aim has been to reach parents, teachers and school officers of rural and other elementary schools, and the owners and caretakers of all classes of live stock, and lay before them the' founda- tion facts and principles underlying the growing and im- perative demand for a more nearly adequate supply of pure air than is being continuously maintained in the vast majority of home's, offices and stables today. In presenting the subject the effort has been to make the treatment suggestive to teachers, introducing lines of simple experimentation and arithmetical calculations, so that they may more surely enlist the attention and coop- eration of their community in the immediately practical aspects of the subject. It is hoped, too, that all owners and caretake'rs of live stock will find the treatment of stable ventilation sufficiently explicit and illustrative to enable them to readily and effectively solve their own prob- lems. In applying the principles used in stable ventilation to dwellings, office's and school-houses, where mechanical ap- pliances or hot air furnaces are not used, we are convinced that there are no practical difficulties in the way and that when such a system of ventilation is combined with the warming as suggested it will be found thoroughly efficient. In the effort to be brief, and yet have the presentation sufficiently fundamental and explicit so as not to mislead, it has been necessary, in the treatment of dwellings and schools, to omit details, yet it is hoped enough has been given so that with the aid of builders and local architects installations may be readily made. F. H. King. Madison, Wisconsin. Nov. 23, 1908. "And did it occur to you that here, too, was another bellows feeding air into another forge, keeping the fire of life aglow and timing its Intensity to the work to be done?" — Page 1. INTEODUCTION Have you stood in a smithy's door and watched the cold bar of iron mount by quick steps to a white heat as the strong arm on the bellows compelled fresh air through the bed of coals on the forge ? Did you reflect that that inter- mittent air current contributed more pounds avoirdupois to the. generation of the heat than did the coal, in the ratio of about 8 to 3 ? Did you note the capacity of the huge bel- lows, the powerful lever with which it was worked, the length of the strokes and the weight which the smith threw onto the bellows to feed sufficient air to his forge ? Did you note the rythmical rise and fall of the smith's deep chest as he moved about his work? How the heaving quickened and deepened as the blows from the hammer fell more swiftly and with greater force upon the shaping piece? And did it occur to you that here, too, was another bellows, feeding air into another forge, keeping the fire of life aglow and timing its intensity to the work to be done ? Did you observe how thoroughly the smith kept drawing up over his fire a blanket of cinders and coal, that the heat should be retained where the work was being done and that as little as possible should be wasted ? And did you realize how much more this greater economy made the action of the bellows necessary to carry sufficient air to the exact place where it must be used ? And do you realize with what con- sumate economy all the forges of life, whether of man, beast, bird or bee, have been housed in from the cold and are continuously fanned, whether waking or asleep, by au- tomatic bellows, thus generating the maximum of energy with the minimum of fuel and of labor ? 2 Ventilation. Now when the best results from the forge demand a con- tinuous action of the bellows, feeding in more than 11 pounds of pure air through the fire for each pound of coal burned, and when the health and best action of the smith demand more than 20 cubic feet of pure air per hour, what would you think of setting up and operating, in an 8 by 8 room without chimney and with doors and windows closed, such a combination of forge and man during ten consecu- tive hours, depending for the renewal of air upon such leakage as may take place through walls and ceiling? And yet are not conditions more deplorable than these found in many a sleeping chamber, stable, bee-hive, factory and church? Do we not realize and generally practice in ac- cordance with the fact that closing the drafts in a stove checks the intensity of the fire or extinguishes it altogether ? Do we not understand perfectly that the proper action of a stove or of a furnace can only be secured through the ef- fective action of a good chimney? Do we not know most thoroughly that we may go for days without food, and even without water, but that to be deprived of air for only a few minutes results in the greatest distress and may even prove fatal? Have we not felt the oppression which follows the closing of ventilators and windows of a crowded coach for only a minute or two to shut out the smoke while the train passes through a tunnel, and do we not recall how everyone is looking anxiously for the windows and ventilators to be opened the moment the train emerges ? How can it be, then, that today, even in cities where homes are planned by trained architects, little or no thought is given to making special provision for ventilation in the majority of dwellings. First of all, must not the house be cheap, then if it can be warm, light, convenient, commod- ious and attractive are not these clear gains? If we can cook, wash and iron with gasolene, a blue-flame oil stove, gas or electricity, then may not the expense of one chim- ney be saved? And if we will heat the house with hot water or with steam may not every room then be as nearly an air tight box as the materials and the mode of construe- Ventilation of Body Tissues. 3 tion makes possible ? And with such arrangements may not the work and the warming of the house be done with the least possible expense for fuel? Most certainly, but how about the health and comfort of the family for whom the home was built? Which is better, a close house with but little air, to be breathed and burned over and over again, with langour and irritableness, and perhaps less of service through sickness and a large doctor's bill, or an airy home, full of buoyancy, cheer and health but perhaps a trifle larger bill for coal? Is it urged that the wind will force air enough through the house and stable even with the closest possible construc- tion ? But how about the days and the nights when there is little or no wind ? Then the windows may be opened ? But who thinks to do this at the right time? Perhaps the one in the family who suffers most from insufficient change of air is too unselfish or too sensitive lest some one else would be disturbed by opening the windows, or perhaps the herds- man has too little thought for the animals in the stable to take the necessary trouble at the proper time. Clearly, if an abundant change of air is needful, a flow should be con- tinuous and sufficient at all times, whether we are awake or asleep, and whether attention is given to it or not. That an abundant change of air in the house or in the stable is needful there can be no doubt, and that this cannot take place unless proper arrangements are provided for it is likewise evident. NATIJRE S PROVISION FOR VENTILATION OF BODY-TISSUES. So great, so imperative and so constant is the need of fresh air in the maintenance of vigorous bodily functions that the delicate lining membrane of the lungs of an ordi- nary man, in contact with which air is brought and through which all the blood of the body circulates, were it spread out in a continuous sheet, would measure no less than 236 square feet, enough to cover the sides, floor and ceiling of 4 Ventilation. a room more than 6 by 6 by 6 feet, and that of a 1000-pound cow would similarly cover a room 11 by 11 by 11 feet. Plg^. 3.— The area of this room, walls, floor and ceiling, 6 by 6 by 6 feet, represents the amount of surface in the lungs of an ordinary man through which all the blood of the body passes about twice every minute, to be brought close to the air which is changed by the act of breathing 15 to 20 times per minute. Such enormous surfaces as 236 square feet of delicate lining membrane, in the lungs of man, and of 1,500 square feet in those of the cow, may seem impossible. That this is not so may be understood when it is said that a box one foot on each side has an inside surface of six square feet. Pass a partition through the center of this box each of the three ways. The eight chambers so formed have double the ag- gregate inside surface of the original box, or twelve square feet per cubic foot of space. By passing ten planes through the box in each of the three ways we would increase the in- side surface ten-fold, giving it 60 square feet, and so 40 such partitions passing in each of the three directions would increase the inside area 40-fold, giving just about the lung surface for man, and yet each of the 64,000 small chambers so formed, three-tenths of an inch on a side, would be very much larger than the actual air-cells in the lungs. In the Extent of Lung Surface. 5 box represented in Fig. 3, subdivided by 40 planes passing^ each way, the small divisions are each one-twelfth of an inch in diameter, easily visible, and the total wall surface formed by them measures no less than 18.5 square feet and about one-twelfth the lung surface of man, thus making it clear how a very large surface may be developed in a smaD space. rr \\\\\\\\\\\\\\\\\ - \ \ ] ] ] } } 1 } ) , } f ? ? ^ ^ ^j -iV \\\\\\\\\\\\ W \,\ \ — — / / / / 1 //////// /////. \' v\\\\\\\\\ \ \ \ \ \\ \ - — // 1 If / / / / / /////M. \ \S->.\\\\\\ \\\\\\\ \ \ \ 1 - /////// /// /// ////Ay y \ s s. 4. N.NJK\ \ '^' V \\ •.■•.'f f'' ^■' ,^^ ::-"::::":ii:i -- ^ ^ '• ■ .r : ::.:.::::: j- "' -' ^ ' :_ . • ,■-■! ^ r ,- ' ^ ' . - ' ^ -Iffi , . •■ - ■ ' ' . -' ■ U ■ _ . -' .. ■■ . ■ -'' - - — . ■■ ■' _,--■■" "" " — .-J- .t ~~ ~ ' ■■■■T — . . .. i" "" y / / , , ' / / / / / 1 1 . '""■■- — . _ J 1 - - L " ■ - " ■ - -- 1_! ■ ■ 1, ■ - - . il :~:'::: ::::" :"::: ; " ■ ~ - "" ~ - - "" • - " - -. 1 " ■ ■^ " ■• ^ ' U ; : ------- ;::;;§;:; j_| . - - - _ M\\\\\\;\\\:\:\:^nS^ / ■ j' / //////,///] // / //// / / / / / f 1 I \ \ \ \ \ \\^ ^ \\\\\ \\\xl;^,\ '^///////////fll / c. ///////// fll / / / \ \ \ \ \ \ \ \ \ \ \ \w w^^'^ ^ vrf <' ' ' / t ' / 1 1 1 1 I I \ ' \ \ \ \ \ \ \ \ \ V V \ V \ \ \ \ \ \\ Fig. 3.— A box the size of this drawing, subdivided by as many parti- tions as are represented by the lines, would form 64,000 chamber* having a total wall surface of 18.5 square feet, one-twelfth that in the lungs of an ordinary man. Now imagine blood flowing steadily through a close net- work of capillaries within all the partitions in this box, and at the same time, by a bellows-like action, that the air is drawn into and forced out of it 15 to 20 times every 6 Ventilation. minute, and you have, then, a fairly truthful illustration of the principle underlying the mechanism by which the blood of the body is brought continuously into close touch with a fresh supply of air. The blood vessels, bringing all of the blood of the body to the lungs, subdivide and spread out until they expose to the air in the air-cells some 236 square feet of blood surface, flowing in the thinnest possible streams almost in touch with air on two sides, which is being renovated by 15 to 20 respirations every minute, while the powerful action of the heart drives the whole blood of the body over this large surface once every 20 to 40 seconds. There is another remarkable feature in the wonderful mechanism which nature has found necessary to make sure that oxygen shall be brought to and carbon dioxide re- moved from the body tissues as rapidly as is needful. The water of the blood, although comprising 80 per cent of its weight, does not have a sufficiently strong absorbing power to permit it to take up oxygen in the lungs, exchanging it for carbon dioxide in the tissues, as rapidly as is needful and hence more than half the volume of the blood is put into the form of circular, cracker-shaped disks called the red corpuscles, giving its characteristic color. These cor- puscles strongly absorb oxygen when in the lungs and ex- change it for carbon dioxide when in the tissues, thus act- ing like so many conveying buckets which are continuously loading and unloading with each round trip and yet with- out stopping. Moreover, to make sure that each one of these carriers shall be brought in touch with air before it can re- turn to the body, the diameters of the capillaries are made so small that these absorbing disks are compelled to pass through them almost in single file with both faces almost continuously in touch with the lining membrane of adjacent air cells, thus insuring ample opportunity for the unloading of the carbon dioxide brought from the tissues, and for the reloading with oxygen to be carried back. There is represented on the right in Fig. 4 a face view -with a cross-section of one of these oxygen and carbon diox- Carriers of Oxygen-food. 7 ide carriers magnified some 2,650 diameters, and on the left a single capillary with the corpuscles passing through it in single file. Pig. 4; — Here is seen, on the right, the shape of the oxygen and carbon- dioxide carriers in the blood of man, magnified 3,650 diameters and, on the left, a line of them passing single file through a capillary, magnified about 600 diameters. These carriers of oxygen-food to the body tissues and of carbon-dioxide-waste from them, although so extremely minute, are yet so numerous that the total surface of the corpuscles in the blood of an ordinary vigorous healthy man measures no less than 49,000 square feet, or more than a full acre. Think of the heart, with its 70-odd strokes per minute, sending more than a full acre of bucket faces through the 236 square feet of partition surface in the ventilation chamber of the body once every 20 to 40 sec-^ ends, and the air of this chamber changed 15 to 20 times every minute ! Nor is this the whole story of the structural arrangements in the mechanism of breathing by which the body tissues shall be fed oxygen and freed from carbon-di- oxide-waste, for it is at once clear that the flattened shape of the blood disks gives to them not only the largest ab- sorbing surface but at the same time it provides the short- est possible distance over which these gases must travel to enter, and leave the tissues, which must take place by the only available but peculiarly slow process of diffusion. Everything, therefore, points to the most imperative need of a thorough ventilation of the body tissues. But when we- are brought to realize how superlatively efileient this mech- -8 Ventilation. anism for breathing is we can never afford to forget that it grew into its marvelous efficiency unhampered by any of the restrictions or constrictions imposed by fashion, and when all of the breathing was done in the pure free air of field and forest. Nature has provided a very large margin of safety in this, as in other matters meaning life or death to organisms which are the present survivors of uncounted generations which have come and gone. For such as are content to bestow their affections upon pug dogs while they give their lives to the amusement of a brotherhood enter- taining if possible less lofty aims in life perhaps the world need not be concerned ; but for those who project their lives into the future may God and all the forces which conspire to better living do everything possible to make deep breath- ing easier and more certain and to maintain a standard of purity of air in the home and in the stable which ap- proaches closely that in the open field. It is along such lines of the fullest utilization of our natural resources, even more than to the husbanding of them, .that we need to look if a race shall be perpetuated capable of highest civilization and which will be lead on by higher ideals. How can we hope to combat disease, maintain and transmit bodily vigor, when the very breath of life is shut out of our bodies by thoughtless false standards of dress and from our homes and stables by lack of sufficient thought given to proper construction ? • AMOUNT OP AIR REQUIRED FOR A DAILY RATION. The complete consumption of a pound of hay or of grain, in the body of an animal, converting it into carbon dioxide and water, would require the same amount of oxygen as though it were burned in a stove or on the grate of an en- gine boiler. Speaking in approximate round numbers the burning of a pound of hard coal requires all of the oxygen carried in some 11 pounds, or 136 cubic feet, of air and the burning of one pound of hay requires all the oxygen in .some 5 pounds or 62 cubic feet. But when rapid and com- Amount of Air Required Dadly. 9 plete combustion takes place not all of the oxygen in the air can be consumed and hence much more than 136 cubic feet of air per pound of coal, and than 62 cubic feet per pound of hay, must pass through the fire box for each pound of material consumed. Moreover it is important to keep in mind that air is as much a part of the fuel which produces the fire as is the coal or the wood, indeed, even more so when considered pound for pound. And so is the air an animal breathes as much an indispensable part of the food it consumes as is the hay or the grain eaten. In the furnace neither can burn without the other and so, within the animal body, neither assimilation of food nor genera- tion of energy can take place without the consumption of a proportionate amount of air. When an engine is being crowded to its full capacity in the generation of power not only must the stoking be more rapid but the drafts also must be opened wider that more air may pass through the fire ; and so it is with an animal when doing work, no mat- ter of what kind, it must breath more deeply or more fre- quently. We realize this clearly in our own case and we see it in the horse, the ox or the dog, when they are in vio- lent exercise. Even in the case of the heavy feeding of animals for the production of milk or of flesh proportion- ately more air must be breathed, and hence when animals are closely housed under these conditions more air should pass through the stable each day. The amount of pure air which must be breathed by differ- ent animals during 24 hours, in order to supply the oxygen needed, computed from Colin ^s table, is given below: Amount of air 'breathed ly different animals. Per hour. Per 24 hours. cu. ft. lbs. cu. ft. Volume. Horse 141.7 116.8 46.0 30.2 17.7 1.2 272 224 89 58 34 2 3401 2804 1103 726 425 29 15 X 15 X 15 ft. Cow 14 X 14 X 14 ft. Pig- 10 X 10 X 10 ft. Sheep 9x .9x 9 ft. Man 8 X 8 X 8 ft. Hen 3 X 3 X 3 ft. 10 Ventilation: From this table it appears that a horse must draw into and force out of his lungs, on the average, each hour, some 142 cubic feet of air, the cow 117, the pig 46, the sheep 30 and the man 18 cubic feet. These volumes are represented in Fig. 5. \ S ""s "" V ^- ~^ " * ^^ J^ — -s V .-:3>. /f ,,. ••--•, l< y ,c . -/'-- / A Pig. 5.— Here each small square in tlie illustration represents one foot and each pile of cubes the volume of air breathed each hour, which should be nearly pure. If it were necessary to supply air to our stock as we do water the horse would require continuously 7 full pails per minute; the cow, 6; the pig, 2.3, and the sheep, 1.5 full pails of air, and these are the amounts required when it is supplied pure and fresh with each respiration, as would oc- cur out of doors where there is a free air movement and where the air thrown off from the lungs is at once borne away by the winds. Inside a dwelling or stable the condi- tions would be very different unless some means were pro- vided to maintain a constant change of air at the proper rate. Air Breathed Loses in Sustaining Power. 11 AIR ONCE BREATHED HAS LOST MUCH OF ITS SUSTAINING POWER. Air once breathed has lost much of its food value or sus- taining power and, impossible as it may seem we have known horses to suffer from breathing Impoverished ^^^ when plowing m the open field. This may occur where three horses driven abreast have their heads close aid so directed that the middle animal is compelled to draw hk hfei; r '""V"^'' '""'^'^ °"t by the other two and ,the exhaustion or fatigue of the center horse can oftm be made noticeably less when a " spreader " or the habit of driv! mg requires the outside animals to breathe straight in front or a httle outward. Three heavy horses at ha?d laborTn mg value to such an extent that when the outer horses are permitted to travel a little in advance and at the same time mcline their heads in, the center animal is placed at a gre"t disadvantage m being compelled to breathe partly 2 hausted and otherwise viti- ated air, for the case is like feeding the firebox of one en- gine from the smokestacks of two others. So, too, when a large number of sheep are driven long distances in a closely huddled flock much discomfort results from their being compelled to breathe exhausted air. Everyone has observed that of two glowing coals in the open air the one which has a strong current forced across it burns more rapidly and with a more intense glow. Why is this? Clearly because one has a more rapid change of air, IS better ventilated, even though both may be out of doors. Immediately about the burning coal the oxygen of Fig. 6.— The air blown across one coal increases the glow. 12 Ventilation. the air is both partly exhausted and diluted, and the cur- rent drives the used air away, bringing fresh air instead. And so ventilation, even out of doors, may be helpful. The lamp without a chimney gives little light and smokes badly but the flame surrounded with a chimney, which seemingly shuts off the free access of air, burns much better and simply because it gets a more rapid change of air. The chimney compels a stream to flow rapidly close to the flame and thus is swept away the used air while a fresh supply takes its place. And so, the lamp, the stove, the engine and the forge, whether in an enclosure or out of doors, must have a mechanism securing a continuous forced change of air; and the respiratory movements of every air-breathing animal tell of the same imperative need. And yet, dwell- ings and stables are planned, adopting increasingly close •construction, allowing ventilation to be brought about inci- dentally as it may, without special provision. Only last summer in conversation with a New York City architect it appeared that he had recently completed a residence in ce- ment concrete and was much surprised to find that the fire- place would invariably smoke unless a door or window of the room was open. Here is perhaps a more striking demonstration of the need of ventilation and of the fact that air once breathed has lost in sustaining poweT. In the illustration. Fig. 7, from a photograph, a coil of magnesium ribbon is shown burning in ordinary air sup- plied by convection currents through the open mouth of a two-quart Mason jar. The intense light which fills the jar and the cloud of white smoke escaping above show how strong is the burning; while in Fig. 8 is shown Fig. 7. — Magnesium ribbon burning in ordinary air. Composition of the Atmosphere. 13 a similar piece of the same ribbon burning in the same jar, but here supplied with air from the lungs, conveyed through the rubber tube. Very markedly less intense is the burning and the light pro- duced in this case, and far less is the cloud of smoke. It is of course the' diminished volume per cent of oxygen carried by the respired air which causes the difference in the intensity of burning, for the rate of change of air is greater in this case. The composition of pure dry air and of air carrying 75 per cent of its saturated volume of moisture, deduced from data of Clarke published in 1908 from the most recent and authoritative determina- tions, are given in the next table : Pig. 8. — Magnesium ribbon burning in respired air. Composition of the Atmosphere. Dry air: Carbon dioxide Oxj^g-en Nitrog-en and otlier g-ases Air. humidity 75 per cent : Carbon dioxide Oxygen Nitrogen and otlier gases Moisture Volume per cent. .0292 20.941 79.030 .028 20.582 77.677 1.713 Cubic inches per cubic foot. .506 361.860 1365.634 .484 355.657 1342.256 29.603 14 Ventilation. On the average, in the case of man, it is found that once respired air has lost oxygen to the extent of 4.78 volume per cent. It has acquired 4.35 volume per cent of carbon dioxide and has become saturated with moisture at the tem- perature of the respired air, while its volume has been in- creased by the expansion due to the rise in temperature. Each of these changes reduces the absolute amount of oxy- gen which may enter the lungs in a given time when the air is respired again, unless the depth or frequency of breath- ing is increased. The changes in composition which come to once breathed air are indicated in the next table, where dry air and that 75 per cent saturated with moisture before breathing are the basis of computation. Composition of pure air and of that once breathed. Dry air: Oxygen Carbon dioxide Nitrog'en and other gases. Moisture Air. humidity 75 per cent : Oxyg-en Carbon dioxide Nitrogen and other gases. Moisture Pure air, cubic inches per cu. ft. 361.860 .506 1365.634 355 . 657 .484 1342.256 29.630 Airbreathed. cubic inches per cu. ft. '265.920 72.059 1300.400 89.638 264.330 73.232 1300.800 89.638 Change, cubic inches —95.94 +71.553 —65.234 +89.638 —91.327 +72.748 —41.456 +60.008 Here it is seen that air once breathed may contain, per cubic foot, from 91 to 96 cubic inches less oxygen, more than 70 cubic inches increase in carbon dioxide and, if the air is dry, some 90 cubic inches more of moisture. The oxy- gen has been decreased from a volume per cent of 20.94 to one of about 15.39, thus leaving it only three-fourths as rich in its essential food element. This reduction of the oxygen content of the air, first by the direct consumption of it and, second, by its dilution through the addition of other ingredients and by expansion due to rise in temper- ature, must be the main change which reduces its sustain- ing power. Indeed breathing becomes difficult so soon as Composition of Once Breathed Air. 15 the volume per cent of oxygen in the air has fallen as low as 13, so that breathing the air but twice would carry the volume per cent of oxygen below this limit, indeed as low as 10 per cent if no fresh air were added JHili^A^ to it. We have seen with what dimin- ished brilliancy a magnesium rib- bon burns in air once breathed. Here is perhaps a more convincing concrete demonstration of the loss of power to support combustion and to sustain bodily functions which characaterizes respired air. Fig. 10. — Caudle extinguished in air once breatlied. Using again the two-quart Mason jar, Fig. 9, let a lighted candle be lowered into it. It burns with scarcely diminished intensity, as did the ribbon, for down- going and up-going currents maintain a continuous fresh air supply. Now while the candle is yet burning let a gentle stream of air from the lungs be conveyed to the bottom of the jar, Fig. 10. Gradually, as the jar fills, the flame loses in brilliancy and finally is extin- guished. The flame in this case is certainly not blown out by the air current for the candle may be relighted and again Fig. 9. -Candle burning in pure air. 16 Ventilation. lowered into the jar after removing the tube. The respired air is heavy enough to remain and, as the candle is lowered into it, it will be extinguished, even after the lapse' of more than two minutes if the air in the room is still. Once more let the candle be lighted and lowered into the jar, Fig. 11. Gradually raise the' can- dle as the flame shows signs of go- ing out. Observe that the respired air tends to remain at the bottom, as may be proven by repeatedly lowering the candle, observing that as this is done the flame tends to Fig, 11. — The respired air tends to remain at the bottom. become extinguished. As the air is forced continually into the jar it becomes gradually filled and the lighted candle has taken the posi- tion represented in Fig. 12. But even here, if breathing into the jar is continued, the flame will be extinguished as the out-coming re- spired air surrounds the candle and shuts off a fresh supply from the flame. Clearly, then, air once Fig. is.-jhe flame is extin- *; ' ' . guished even when held breathed is not suitable for respir- above the mouth of the jar. ation unless much diluted with pure air. Continuous Flow of Air is Necessary. 17 A CONTINUOUS FLOW OF AIR IS NECESSARY. Since once-breathed air is not suitable for respiration until much diluted with that which is pure it follows that into and out of dwellings, schools, churches and stables, so long as they are occupied, must be maintained a sufficient and continuous flow of air to bear away that whose food value has been reduced and to restore an equal volume of that which is pure. Let us again use the two-quart Mason jar. Fig. 9, for another demon- stration. With the candle resting on the bottom and the mouth of the jar unobstructed the flame burns with a steady uniform bril- liancy. By holding the hand above its mouth a strong ascending cur- rent may be distinctly felt, but such a continuous up-going cur- rent of air from out the jar can only be possible when an equal counter current is maintained and it is this which sustains the flow. Now, with the candle still burn- ing in the jar let these in-going and out-going currents be com- pletely stopped by screwing in place the cover of the jar, Fig. 13. With watch in hand it will be found that in even less than 30 seconds the flame is extinguished. ^quart^s~of^air^?xtfngSishIs Thus it is demonstrated that an "^^^^ ^^ ^^ seconds. ordinary candle' spoils for its own use a full gallon of air per minute ; 60 gallons per hour ; and more than 200 cubic feet per^day. Twenty- four such candles would vitiate the air of a room for themselves and for you at the rate of 200 cubic feet per hour. The small portable kero- sene oil stove so frequently used to warm rooms demands 18 Ventilation. more air than twenty-four candles and hence the rate of change in the room for such conditions must much exceed an hourly flow of 200 cubic feet, which is more than 33 cubic feet per minute. As the candle in the Mason jar ex- tinguished itself in 30 seconds where the walls were abso- lutely air-tight it is clear that in every room and in every stable there must be either unintentional leaks for air to enter and escape or else definitely provided openings ; other- wise neither lights nor life could be long maintained. Fortunately for mankind and for his domestic animals it has not been practicable to build either dwellings or stables even approximately approaching the degree of impenetra- bility for air possessed by the Mason jar. But both poorly lighted basement dwellings and stables and the old prison walls and dungeon cells have come dangerously near this limit. Air has entered and left dwellings and stables through openings formed by loosely fitting doors and win- dows, and in varying degrees under the pressure of the wind through the walls themselves. Then too, the oldtime fireplace, the kitchen range and the heating stove have served a sanitary mission of the greatest importance in that they have always compelled a more or less continuous in- flow to dwellings of so much fresh air as equalled the out- go through the chimney. But the fireplace, for continuous service, has long since passed. Heating stoves are being re- placed by hot water and steam radiators and the air which warms these misses entirely the life-giving functions for it enters only the basement rooms, leaving by the furnace flue, no part of it having served the purpose of ventilation. Even the kitchen stove is being displaced by the oil, gas or gasolene range, deadly from the standpoint of pure air, for they tend simply to revolve large volumes of the air. of the room over and over, consuming its oxygen and adding to it all of the products of combustion, for ouly rarely are they connected with a chimney. It is of the highest sanitary importance too, in its bear- ing upon the general health and bodily vigor of the future, to recognize that in the passing of lumber as a building Definite Provision for Air Movement. 19 material and in the substitution therefor of masonry, metal and various filled and painted compositions, both for out-' side and inside finish of dwellings and stables, we are stead- ily, surely and rapidly approaching the ability of the fruit jar to exclude fresh air, compelling it to enter only through unavoidable leaks about doors and windows. We are even huilding flats with wdndows and doors limited to but one or at most two sides, at the same time piling one over another where the exhausted, fouled and heated air must rise from one to another through ceilings, floor and hallways. The increasing cost of fuel too is leading to the adoption of storm windows and doors for the few provided, to more ef- fectually shut out the wind. It is difficult to imagine more Tinsanitary conditions from the ^' fresh air" standpoint than must be associated with a poorly lighted stack of over- crowded flats piled one above another, warmed with steam or hot water, the cooking and lighting done with gas. "When everj^ adult needs hourly, as food, scarcely less than 18 cubic feet of the purest air to be found out of doors ; when we are making such strenuous efforts to shut this air out of our homes and stables ; when so little specific provision is being made to supply air to them at an adequate rate ; should we not be surprised rather that the dread ' ' Avhite plague ' ' does not take even more, vast as the number now is. And if we shall ever be successful in driving it from among us must not the battle be waged in every home where the children are yet well and strong, by applying continuously and ef- ficiently the ' ' fresh air treatment, ' ' not leaving it to be ad- ministered only at the hospital and to those already stricken ? PRESH AIR SUPPLY CERTAIN TO BE INADEQUATE AT TIMES IP DEFINITE PROVISION FOR IT IS NOT MADE. . Where numbers of individuals are sheltered in compart- ments of reasonable volume and so constructed as to permit of economic warming in severe weather there are certain to be times when the fresh air supply will be inadequate 20 Ventilation. unless definite provision for such supply is made. Let us again have recourse to positive concrete demonstration. Here is a cylindrical metal chamber, Fig. 14, 18 inches in diameter and 20 inches deep having a cover which seals the chamber air-tight by means of its rim dipping under sweet oil carried in a groove formed about the top. Around the Fig. 14.— A ventilation chamber for observing the effects of inadequate change of air. sides are arranged a series of six openings each. .71 inch in diameter, which may be closed by means of screw-caps ; and two air-tight observation windows of glass. In the cover is a ventilation opening over which may be screwed a short ventilating shaft beginning at the cover, or an- other long enough to withdraw air from near the bottom. Inside the chamber is placed a lighted kerosene lamp with a No. 1 burner carrying a five-eighths inch wick, and turned up until, in an abundant supply of air, it burns kerosene at the rate of 13.783 grams per hour or .109 gallons per day. With this apparatus the following results were ob- tained : (1) With this ventilation chamber in the still air of a room, with the cover on but not sealed with oil; with the ventilator closed and with the six windows open, each pro- Experimental Ventilation Chamber, 21 vided with a thin muslin screen possessing a pore space through which air may pass equal to 29 . 36 per cent of the total area, it was found that in two minutes the flame dropped from full height to below the top of the shield of the burner, and went out at the end of 11.5 minutes. Here we have the conditions of a steam or hot water-heated room provided with six open but screened windows, in which the lamp could burn but 11.5 minutes. (2) With the six windows open but screened; with the ventilating shaft in place, open and drawing air from the floor level, the flame dropped below the top of the shield in 6 minutes and was extinguished in 23.5 minutes. Here we have ample opportunity for air to escape from the room but inadequate entrance capacity. (3) With the six windows open but screened; with the ventilating shaft in place but drawing air from the ceiling, the flame fell below the top of the shield at the end of 9 and was extinguished at the end of 27 minutes. In this case, with the hottest air at the ceiling and able to enter the ventilating shaft at that level, a stronger draft was pro- duced, compelling a larger supply to enter through the- window screens. ^ (4) With all of the conditions the same as in (3) except that the muslin was removed from one window, in 16 min- utes tlie flame fell below the top of the shield but at the end of two hours was still burning, showing no signs of going out. In this case the hottest air is able to fill the ven- tilator and with the same difference of pressure but with one window entirely free more air may be drawn in in a unit of time, the amount being barely sufficient to maintain a small flame. (5) When an 8-inch electric fan was so placed as to throw a strong current of air directly across the top of the ventilator, but with no direct current against the windows, the small flame being maintained under the conditions of (4) was in one minute increased in size to its normal free air dimensions. Here we have flve windows screened, one window open, and a strong wind blowing across the top of 22 Ventilation. the ventilator, the wind increasing the draft until the cham- her is sufficiently ventilated to meet the needs of the lamp. ( 6 ) With the fan still run- ning and unchanged in posi- tion with but the ventilator closed the flame in 6 minutes fell below the shield on the burner and at the end of 16 minutes had extinguished it- self. With the strong wind blowing over the top of the chamber, with the six win- dows open and five of them screened, but without an ac- tive ventilating shaft, an in- adequate supply of air was provided. In Fig. 16 are shown the rslative dimensions of the flame under the five condi- tions stated by the corre- sponding legend. In these trials the wind blew directly against the windows and sides of the chamber and the air movement was meas- ured with a delicate air meter. In another demonstration a silver-laced Wyandotte roos- ter weighing 5 . 5 pounds was substituted for the lamp in the chamber of Fig. 14. The ventilator and five windows were closed, the other screened with muslin. Under these con- ditions and surrounded by an air temperature of 60° F. at the end of 5.5 hours the bird was in distress, breathing lieavily, gasping with each inspiration. At this stage the six windows were all opened but covered with the screens and 2.5 hours later the bird was still breathing even more heavily and with greater distress. The ventilator in the cover was then opened but covered with a screen. After 10 hours there had been perhaps a little improvement, if so it was very slight. The screens were then all removed from 15. — Wind across ventilator increases draft. Effects of Insufficient Ventilation. 23^ windows and ventilator and at the end of 2 hours the roos- ter was standing up apparently comfortable and breathing normally, presumably he was getting air sufficient to meet his needs. It should be observed, however, that in this case special provision is made for both incoming and outgoing^ currents. VARIATION IN THE SIZE OF FLAMES UNDER PERFECT AND IMPERFECT VENTILATION r ....1- 1. Windows all open; wind 7.39 miles per hour; ventilator at top. 2. Windows all open; air still; ventilator at top. 3. Windows all open; air still; ventilator closed. 4. Screens on all windows; wind 10.97 miles per hour; ventilator closed. 5. Screens on all windows; wind 3.26 miles per hour; ventilator closed. Fig. 16. — Here are represented five sizes of flames, natural size, as they "vrere maintained nnder the ventilation conditions named in Nos. 1, 3, 3, 4:, 5, the burner being that of the lamp and the chamber the same- as shovrn in Fig. 14. A hen "of the same breed weighing 4 . 5 pounds, placed in^ the same chamber with all openings closed, became severely distressed for want of ventilation at the end of 4 hours, 13 minutes and died from the effects 4 minutes later. In this case the cover was sealed with oil and corresponds with the trial with the candle in the two-quart Mason jar, Fig. 13, which extinguished itself in 30 seconds, the chamber having- 44 times the capacity of the two-quart jar. The candle was^ "24 Ventilation. breathing in 115.5 cu. in. of air and died in 30 sec, using -3 . 85 cu. in. per sec. ; the hen was breathing in 5,089 cu. in. and died in 15,420 sec, using but . 33 cu. in. per sec. SERIOUS EFFECTS FOLLOW INSUFFICIENT VENTILATION. In the demonstrations made with the ventilation cham- ber referred to in the last section (Figs. 14 and 15) it was made clear that as the ventilation became less and less per- fect the size of the flame of the lamp was reduced until in the end it was no longer able to maintain itself. So, too, must it be with the functional activities of the body. The processes and conditions which maintained the flame of the lamp are identical in principle with those which maintain the functional activities of the various organs of the body. The rate of the carrying of oxygen to the flame and that of the bearing away of the products of combustion determined its size and the intensity of the heat and light generated by it, these decreasing from 1 through 2, 3 and 4 to 5 as the air movement through the chamber became less rapid, and so it must be with those functional activities within the animal body which constitute the sum total of its life ; these must decrease in intensity or magnitude of activity just in pro- portion as the life-giving oxygen is borne to, and the waste products are carried away from them. Blood passing through the active tissues is fully vitalized only when it is doubly charged, first, with the oxygen from the air breathed and, second, with the other nutrients eaten and drank. Neither can be efficient except as the other is present, ample and effective. The lamp, under the condi- tions of 5 had an abundance of oil, the wick was full, the temperature right but the oxygen was deficient. There could be no larger product in the form of flame except as the oxygen supply was made continuously larger. The con- ditions for activity in the body tissues are no less rigid; they are of the same type. It requires more oats and more liay to maintain day after day a team turning two 18-inch furrows than it does another turning two of 12, and pro- Serious Effects of Insufficient Ventilation, 25 portionately more air must be taken in. If you increase the daily ration of grain and hay with a view of doubling the output of milk there is no other possibility for the herd than for it to charge its blood with enough more oxygen to make the extra product. If the herd is in the free air of a pasture it will do this easily, automatically and with cer- tainty, but if it is in a stable and that stable has a wholly inadequate air movement through it ; if the quality of the air in it is to that of the pasture as is the air in the ventila- tion chamber (Fig. 16) under the conditions of 3, 4 or 5 to those of 1, then the herd will be helpless to help you and a, menace to those who use its product. The extremely serious aspect of inadequate ventilation results not so much from its effects in diminishing func- tional activities and in depressing the vital powers in their ability to do useful work as in its tendency to derange the order of chemical processes in the body leading to the for- mation and accumulation of products in the tissues which render the individual w^hose functions are so disturbed pe- culiarly liable to disease and especially to those of zymotic or contagious types, such as cholera, smallpox, diphtheria and tuberculosis. This world is marvelously full of germs of unnumbered kinds and possibilities. Let a fire sweep away any forest, no matter how dense or how many cen- turies old, with the first rain and genial sun there springs out from the ashes, upon almost every square inch of sur- face laid bare, some plant from seeds, perhaps of a hun- dred kinds, wafted thither by the winds, floated on the waters, brought by the birds or dropped by former occu- pants of the soil; seeds which have laid dormant perhaps many years or which have been resown a thousand times, waiting the moment when the forest should lose its mas- tery over the soil. Nature has neither empty places, idle moments nor neglected opportunities where the conditions for life exist. Everywhere out of the weak, out of the dy- ing and out of the dead, as well as out of the soil and out of water, life is springing. Eternally is somebody waiting for everybody's shoes, for all life is a competitive struggle, 26 Ventilation. continuous, intense, and hence inadequate ventilation or anything which interferes with the normal action of the body, causing weakness, becomes an entering wedge, open- ing out an opportunity for the attack of some disease pro- ducing germ. Plant any seed in a too cold, over- wet, insufficiently ven- tilated soil and it at once absorbs water, its stored food ma- terials dissolve and, unless the other conditions favorable for germination are present, this soluble plant food will be at once appropriated by the many micro-organisms exist- ing in the soil and which are better able to thrive under the conditions surrounding the seed. The result is the seed is robbed of its stored food, its vitality becomes thereby low- ered and either its life is destroyed or it reaches maturity giving a reduced yield. Likewise we should never forget that in the case of our own bodies and in those of our do- mestic animals there is continually a struggle for mastery between the normal living cells which constitute the various organs and many lower life forms always present in the system as the seed are in the forest soil, simply biding their opportunity. Any condition, therefore, like that of an in- sufficient supply of pure air, insufficient or improper food of other kinds, which must tend to lower the vitality or intensity of action in the cells of any organ is likely to place them at the mercy of the invading germs which, like weeds in the field, are simply biding their time to spring into overmastering supremacy, thus bringing disease and perhaps death as the result. We fully appreciate that in a highly fertile soil, well managed, crops are less liable to disease and that they much more readily keep the mastery over weeds than they do on a poor soil or on one in bad condition, poorly managed. It it equally true with the organs of the animal body ; if they are abundantly nourished, surrounded by congenial condi- tions, the possibilities for contracting tuberculosis, cholera, smallpox or other forms of contagious diseases whose germs we must remember are almost always about us, no matter how careful we may be, are very much reduced. It is the Serious Effects of Insufficient Ventilation. 27 body starving for want of oxygen or for want of any other essential food material, or which is weakened in any other way, which is most likely to be overpowered by one or an- other of these foreign organisms, and a single germ may gain the mastery over a system in weakened condition where multitudes of them would be harmless within a vig- orous constitution, well nourished and normally cared for. And since the body out of which life has gone begins immediately to pass into decay it stands to reason that one sick or weak must be more liable to suffer from attack than anotheT who is strong, and the truth of this is abundantly borne out by statistics, particularly by those expressing the rate of mortality resulting from con- tagious disease associated with condi- tions of inadequate' ventilation. As a concrete illustration of the manner in which insufficient air may alter the nature of chemical changes let this lamp, Fig. 17, be' used, which is burning with a full bright flame under the influence of a strong cur- rent of air. The moment this cur- rent is cut down by holding the hand under the draft. Fig. 18, the chimney fills with a sooty flame and smoke. There is not encfugh oxygen carried by the reduced current to unite with both the hydrogen and the carbon of the kerosene and, as the hydrogen Pig. i8.-Lamp burning ^^s a strougcr attraction than the with insufficient sup- carbon for oxygcu, it appropriates so ply of air resulting iti x-r-jr. in smoky flame. nearly the whole that a portion of thef carbon is set free in the form of smoke. There is thus formed a waste product abnormal to the lamp in healthful operation and if allowed to continue would ultimately clog the chim- 3 Fig. 17. — L— *\ m ifeUj'-. "-■■~. m ^ ■ 1. /'-/-: ■-:'.-. -"-iJt ^>0^y^ X / / / P/ / / \ i \ \ \ \ \ X ^s. ^V^V^* y^ ^ y y / y / , r \ 1 1 \ \\\ \V\\\ % ^ /-//// / \\\ / / / m I \\\ \\\\\ ^ ^ ^ y y / / / h p < / / \ \ \ \ X \ V v^^ ^ 2. ^^ ^ / / / / /*= V / A V \\\xxv^ ^ Fig. 20.— Each drawing represents the volume of air which should enter and leave the stable or room during each hour for each adult occu- pant. Each square represents a square foot and the subdivisions indicate the number of cubic feet in each room. horses, for 51 pigs and for 77 sheep. Double the number of animals named will require ventilating flues having nearly double the cross section stated while smaller num- bers would require flues relatively larger in proportion on account of the relatively greater friction in small, as com- pared with that in large flues. To emphasize, we wish again to state that it is a matter of the highest economic and sanitary importance that rigid Volume of Air Required Hourly. 43 experiments should he instituted, both for man and for do- mestic animals, which shall establish beyond all doubt what is an entirely sufficient degree of air purity for dwellings and for stables to the end that a safe basis may be had upon which to specifically provide proper and fully adequate means for ventilation. It is important to recognize that the V ^^-^ 'M ^^--::: ..■■■ ^^-^ ..-'" — "'.'V — ■---^^ "■-, ^ ~- ^ ^ t\- / >:i w^^^mn / / / X \ . A \ \ -si K 1 / / / \\) Ihn ^ \ N \ ^ / / 1 w )y|]\ \ \ sj / / / 1 f - ^^ \ \ \ \ Fig. 21.— Each drawing represents the volume of air which should enter and leave the stable during each hour for each adult occupant. The rulings indicate the number of cubic feet in each room, each square is one foot. standard of air purity here assumed is materially below that which admits a content of carbon dioxide in the air of a room of .07 volume per cent. Indeed the standard as- sumed for stables permits a content of carbon dioxide as high as . 167 volume per cent, a quantity more than double that above ; and it is important to say again here, for com- parison, that Doctor Jordan found in his stable, with the ventilation system in operation, a carbon dioxide content as high as .462 volume per cent, which is nearly three times that of the standard we have assumed for stables. In his 44 Ventilation. case the degree of air purity was 89 . 67 volume per cent in- stead of 96.7 which we have assumed as a probably safe limit. Should it be found admissible to tolerate in a stable 5 to 10 per cent of air once breathed, instead of 3.3 per cent, which is here assumed, such a degree of purity could be more readily secured under all conditions of weather. We feel that it would be unwise, however, to adopt a lower standard, in advance of definite knowledge, in stable con- struction for the reason that it is a very simple matter to reduce the air movement through a stable when the large capacity of the ventilating system causes the rate of change to be too high. If the capacity of the system is too small there is no help except that of resorting to open windows or similar devices which are undesirable in cold weather, par- ticularly if it is windy. PRINCIPLES OF VENTILATION. The installation of a satisfactory system of ventilation re- quires (1) The choice of a proper unit of air movement; (2) the application of the laws and principles governing air movement ; (3) and the adoption of proper construction with adequate motive power to insure the required supply of air. There can be no proper ventilation for dwelling or stable unless into it and out of it there is a continuous flow of air at some proper unit rate. It has been pointed out that some have adopted as this proper unit for man a cubic foot of air per second; that others have accepted one half this volume as adequate ; and that we have taken as possibly sufficient for the cow 3,542 cubic feet per hour. Without contending that either of these units is the best it must be insisted that some unit should he chosen and then adequate provision made to secure at least this amount. It should be recognized, too, that in increasing the air movement be- yond the standard chosen there is little chance that injuri- ous physiological effects will follow as the result of such choice provided a proper temperature is at the same time maintained. Unnecessary expense of installation and maintenance is about the only chance for mistake against which to guard; and in the matter of expense it should be remembered that where the forces which maintain the air movement through the ventilated space are the wind and the waste heat of oc- cupants or of heating and lighting appliances the cost of a ventilating system above the standard capacity will be only that required to incorporate a somewhat larger amount of material in its construction. It is the part of wisdom, therefore, to install a ventilating system whose capacity shall be abundantly large. 46 Ventilation. The maintenance of a flow of air through a building re- quires the continuous expenditure of energy and the amount of this energy and of work done will be in direct proportion to the weight of air moved through the venti- lated space and the resistance it is necessary to overcome in accomplishing this movement. If the air of an audience room occupied by 1,000 persons is supplied at the rate of 537 cubic feet per hour and per capita the work to be done is approximately that of moving some 21^ tons of air through the room each hour. If De Chaumont's standard of one cubic foot of air per second and per person is adopted then the amount of work to be done is that needed to move through the room 144^ tons of air. So, too, if a herd of 100 dairy cows is to be supplied with air at the rate of 3,542 cubic feet per head and per hour the necessary amount of work is that of moving through the stable each hour 14 tons,* which, if the air is forced through vertical shafts 40 feet in length, of ample' capac- ity, represents about one-half horse power. POWER USED IN VENTILATION. The motive power commonly utilized in ventilation is (1) the passing wind; (2) heat generated within the space to be ventilated by its occupants, by lights and by fires; (3) rotary fans driven by one or another source of power; (4) and steam jets or coils in ventilation flues. By whatever source of power the air movement for the purposes of ven- tilation is effected this results from a difference of pressure established between the air in the space to be ventilated and that outside, and this difference of pressure is the immedi- ^ 537X1000 ^<^ ^ 21.48 tons 2000 2 3600 X 1000 X .08 2000 3 3542 X 100 X. 08 2000 = 144 tons. - 14.168 tons. Motive Power in VentUation. 47 ate cause of air movement into and out of the ventilated space. When the wind has its progress arrested or checked by a building pressure is developed ; this pressure tends to force air through any pores, chinks or openings which may exist in the wall. But if air is forced into the building that in- side will be placed under a greater pressure and this greater pressure will force a flow outward on the leeward side or upward through any chimney or ventilating shaft which may exist. All are familiar with the existence of a much stronger current passing around the comer of a building on a windy day than is found at a distance be- yond. This higher wind velocity is proof of the increased pressure which has resulted from the check to its onward progress it has received from the building and this must assist in the ventilation of all buildings whose walls are not absolutely air tight. The pressure of the wind on a building, and therefore the ''head" which tends to force air into it, when the im- pact is at a right angle, has been found to be approximately given by the two equations Pressure or Head = .005 V^ or Pressure or Head = .00096 Y^ where V is the velocity of the wind in miles per hour, the result being in pounds per square foot of surface in the first equation, and in inches of water in the second. These equations mean that if a wind is blowing at the rate of five miles per hour against the walls of a dwelling or stable, striking them at a right angle, the pressure so developed tends to force air through any openings in the windward side with an intensity approximately equal to .125^ lb. per sq. ft. and equal to .024^ inch of water, the precise value varying with the weight of a cubic foot of air at the time, this changing with the temperature, pres- sure and composition. This amount of pressure is the- oretically capable of causing a flow through a smooth, ^ 005 X 5 X 5 = .125 lbs. per sq. ft. 2 .00096 X 5 X 5 = .024 inch water pressure, 48 Ventilation. straight cylindrical ventilating shaft or chimney one square foot in cross-section and 40 feet high, equal to some 36,000 cubic feet per hour. Then too, whenever the wind blows directly across the top of a chimney, ventilator or other opening it tends to pro- duce a suction which has the effect of reducing the pressure at the opening and of causing a flow outward increasing with the reduction of pressure. The magnitude of such wind action, in its tendency to produce a flow of air into and out of spaces needing ventilation, is given by the equa- tion, Pressure or Head = .00024Y2, where V is the velocity of the wind in feet per second and where the head or pressure is in inches of water. If the velocity of the air is taken in miles per hour this equation becomes Pressure or Head = . 000518 Y-. These equations mean that if the wind is blowing at the rate of five miles per hour across the top of a ventilating flue or chimney there would be developed a suctional effect or head equal to, using the second equation, .000518 X 5 X 5 = .01295 inch water pressure, and this is capable of producing, in a flue 40 feet high with a^cross-section of one square foot, a theoretical flow of some 26,000 cubic feet per hour. Such theoretical velocities as these cannot be realized in practice because the resistances met with by the air in entering buildings, ventilating shafts or chimneys vary between wide limits; moreover if provi- sion is made for air to enter through thin openings in walls, such openings are never fully effective because of the inter- ference of currents entering obliquely around the margins, causing a contraction of the air stream which may reduce the theoretical flow to about 65 per cent. The manner in which the wind becomes a motive power in ventilation is indicated in Fig. 22. How Wind is Effective in Ventilation. 49 The wind has its progress arrested by the building, thereby compressing the air and forcing a portion of it into the building through any openings, as at A, while other , , ■;<,!.. ■.'.•:.*•-'. .- - ...,, 3«i "IS/iSWi'*! m=/«»'i w= ►=«iwr»;»FXcgnii»i£h '^.SS Fig. 22.— Manner in which the wind becomes effective as a motive power in the draft of chimneys and in ventilation. portions are driven upward along the sides past B and over the roof across the top of the ventilator at C, and other por- tions still flow around the corners. The air entering the building at A is either forced upward through the ventilat- ing flue at D or out through any openings which may be in the leeward walls of the room. That portion forced past B along the roof, across the top of the ventilator, joins with the general wind current of that level and tends to drive the out-coming air from the flue forward, diminishing the pressure of the air downward into the flue, thus making less resistance for the air in the room below to be overcome in its ascent. The air flowing over the roof of the building in- creases the pressure on the leeward side at E, out from which air flows on both sides, that flowing toward the build- 50 Ventilation. ing rising along the sides or entering it at F, as indicated by the small arrows. Thus two sources of power are brought into operation, compelling air to enter the room at A and F and leave it at D, one being the direct wind pres- sure exerted at A and F and the other the suctional effect developed at C. The flow through the building, resulting from wind pressure and wind suction, will be most rapid Fig. 23. — Showing improper installation of ventilating flues just above the eaves. In such cases whenever the wind is from the opposite direc- tion the tendency will be to give a much reduced draft or even reverse its direction, causing it to be downward into the stable. when these two factors can be made to act in the same direc- tion and with the highest efficiency. This will be the case when the wind is permitted to reach the building at A and to pass over its roof at C, meeting with the least obstructions. The table, page 57, indicates that the flow due to direct pressure is stronger than that due to suction under like wind velocities. It will generally be true, however, that the suctional effect of the wind is the stronger of the two for the reason that the wind velocity at the top of the ventilat- ing flue will nearly always be materially stronger than near the ground. The fact of wind velocity increasing with Defective Outtake Shelter. 51 hight above the ground is expressed in Fig. 22 by the length of the arrows, these being aprpoximately propor- tional to the wind velocities at such levels. It will be clear from what has been said that the top of a chimney or a ventilating flue should rise well above the ridge of the roof, where the wind has a clear sweep, and not end just above the eaves as is the case illustrated in Fig. 23. So, too, it must be clear that anything which checks the velocity of the wind across the top of a chimney or ventilat- ing flue, or which resists the escape of air from them, must reduce the power of the wind to produce draft. Such caps, therefore, as are seen in Fig, 23 and as is represented on a larger scale in Fig. 24, designed to keep out the storm, must necessarily materially reduce the draft and should be avoided wherever possible unless forced ventilation has been adopted and the current is maintained by mechanical power. Fig. 24.— Shelter for ventilating flue, designed for high efficiency in keep- ing out rain but which materially reduces the draft in "natural ventilation." Many forms of cowls have been devised to prevent down- draft in chimneys and ventilating flues, and with a view ta utilizing the wind to better advantage in producing draft. It will seldom happen, however, that these need be resorted to in the ventilation of ordinary farm buildings or rural schoolhouses or churches. One of the mistakes most often made in installing a ventilation system in barns is illus- trated in Fig. 25, where a one-story barn is provided with 52 Ventilation. short ventilating flues which, because they are short, have a low efficiency and then this efficiency is still further reduced by covering the outlet with closely louvred shelters which materially diminish the effect of the wind in aiding venti- lation. i^ iFig. 25. — Low ventilating flues having their efficiency much reduced by closely louvred shelters, diminishing the effect of the wind in pro- ducing draft. A much better construction for the ventilating shaft is Tepresented in Fig. 26 where the flues are not only higher l)ut the outlet is shielded in such a way as not to materially impede the movement of the passing wind or the escape of the air from the ventilating flue. Any condition or cause which changes the density of the air in a dwelling or stable, rendering it lighter than 'ai;i equal volume outside, tends also to establish and maintain a current of air flowing through it. The effect of both heat and the addition of moisture to the air of a room is to ren- der it relatively lighter than the air outside and so long as a difference in density is maintained there is a difference in pressure which tends to compel a continuous flow of air into and out of the space. When air is warmed or cooled its volume changes 7-- for each degree F. rise or fall in temperature. Imagine a Good Termination of Outtake Flue. 53 room containing 491 cubic feet, one very nearly 8 by 8 by 8 feet. If the air in this room has its temperature raised one degree F. the expansion so caused will force out just one cu- bic foot of this air and so, if the temperature is raised 100 degrees, there will be forced out of such a room 100 cubic feet and the air remaining will weigh about 8 pounds less than an equal volume outside. This being the case there must result a pressure inward tending to force air into the Fig. 26. — Ventilating flues rising high above the roof and with outlet sheltered so as to permit free wind movement and easy escape of air from the flues. room, a pressure equal to about .08 pound for each degree difference in temperature, and hence 8 pounds where the difference is 100° F. Referring now to Fig. 27, which rep- resents a room of 491 cubic feet capacity, suppose there is an opening of one square foot area in the floor at A and an equal similar opening in the ceiling at B. If the air in this room is maintained at 70° when the outside air is 30° below zero its weight will be 8 pounds less than that of an equal volume outside. This being true the pressure into the-i'oom at the floor and on sides and ceiling must be 8 pounds greater than that exerted outward by the inside air ; and since the floor has an area of nearly 8 X 8 = 64 sq. ft. 54 Ventilation. the pressure tending to force air into the room at the floor opening and out at the ceiling must be one sixty-fourth of 8 Fig. 27, — Difference in temperature as a motive power in ventilation. pounds, or . 125 lb. per square foot. This too is the differ- ence in weight between a column of air one square foot in section the hight of the room and an equal column outside. So long, therefore, as such a difference in temperature is maintained air must tend to enter at the floor and flow out at the ceiling at the rate which a pressure of . 125 pound Difference of Temperature a Motive Power. 55 per square foot is capable of maintaining, which theoret- ically is more than 25,000 cubic feet per hour. The magnitude of the temperatue effect in producing draft is given by the equation. Cu. ft. per hour = 60 X 60 X 8 -. / ^ ~ ^ H V 491 ivhere 60 X 60 is number of seconds per hour; 8 is ^ 2o-, and g is the increment of gravitj^ 32.16; T is temperature of the air inside; t is temperature of the air outside; H is height of room, chimney or ventilator: ^li is the expansion of air for 1° F. Suppose a ventilation flue one square foot in section 40 feet high, and the air in it maintained at a temperature 20° above the air outside. In such a case the theoretical flow through the flue would be 18,381 cu. ft. per hour.^ This is the theoretical rate of flow, no account being taken of friction or other forms of resistance. The actual flow which would be associated with such a difference in pres- sure might be fully 50 per cent less than this. The effect of temperature differences in producing draft increases with the hight of the chimney, ventilating flue, and with that of the room or stable. It is because of the greater leakage of warm air from rooms and stables with high ceilings that it is more difficult to keep them warm. This will be readily seen from a consideration of the prob- lem presented in connection with Fig. 27, considering the room to have a hight of 16 instead of 8 feet. Such a room would contain twice the volume of air and hence, with the same increase in temperature, the expansion would cause an escape of 16 instead of 8 cubic feet of air. The air of the room would then be lighter than an equal volume of that outside by the weight of 16 instead of 8 cubic feet, and hence there would be double the pressure forcing the air to enter and leave the room. Computing the theoretical 1 60 X 60 X 8 T / — X 40 = 18381 cu. ft. per hour. 1/491^ 56 Ventilation, change of air in the two rooms we shall have for the one with the 8-foot ceiling 36,760 en. ft. per hour/ and for the room with a 16-foot ceiling the rate of air change would be 51,889 cu. ft. per hour. 2' If the two rooms under consideration were not provided with special openings for the' entrance and escape of air, as represented in Fig. 27, and the air was required to enter entirely- through leaks in the walls, approximately the same rela- tive changes of air would take place and it is clear that, it is much more economical, both in cost of construction and in that of maintaining proper temperature to place the ceil- ings of dwellings and stables only so high as is needful to secure convenience and sanitary conditions; aiming to se- cure the necessary rate of change of air through definite provisions in the way of ventilation. It is clearly much cheaper to construct a tall ventilating flue for securing the necessary increase in the rate of air change, than it is to make the walls of rooms and stables higher. In the table which follows there are given the theoretical rates of flow of air through ventilating flues of different hights and under several differences of temperature main- tained inside and outside the flues. Computed theoretical floio of air through straight ventilating jiues one square foot in cross-section, of different lengths and under 8 tempera- ture differences. The ohserred floics are likely to he near 50 per cent heloiD these values. Difference in temp. T-t. Height oe VEXTILATIXG FLITE, H. • 20 ft. 30 ft. 40 ft. 50 ft. 60 ft. 1° 5.828 18.409 26.064 31.922 36.902 41.211 45.144 48,761 Flow, 7.138 22, 572 31. 775 39.096 45.144 50.472 55. 291 59,920 cubic feet pe] 8,^42 26,064 36. 680 45.144 52. 128 58, 214 63.843 68.958 r hour. 9,215 29,114 41.211 50.472 58.214 65. 159 71,378 77,098 f 10,095 10° 31,922 20° 45,144 30° 55,291 40° 63.843 50° f 71,378 60° 70° 78. 192 84, 457 1 60 X 60 X 8 /lOO 1/ 491 X 8 = 36760 cu. ft. per hour, /lOO 2 60 X 60 X 8 -, ./ ±^ X 16 = 51889 cu. ft. per hour. Capacity of Outtake Flues. 57 The relation between wind velocities and the pressures due to impact and to suctional effect are given in the next table, together with the flow of air computed, using the formula on page 55, where the wind pressures in the third and sixth columns have their temperature difference equiva- lents computed and given in the fourth and seventh col- umns, these being used with the formula named. Computed theoretical floio of air through a flue one square foot in cross- section and 40 feet long, due to the direct impact and suction effect of wind at different velocities. Velocity of wind. Per hour, miles. Per sec, feet. 1 1.47 2.93 4.40 5.87 7.33 8.90 9.87 11.73 13.20 2 3 4 5 6 7 8 9 10..' 14.67 11 16.13 12 17.60 13 19.07 14 20.53 15 22.00 Direct impact. Suctional effect. Press- ure. Inches of water.: degrees. Flow Eciulva- ^^r^\^* per hour, ^-^- ' cu. ft. .001 .0039 .0087 .0155 .0242 .0.349 .0475 .0620 .0785 .0969 .1172 .1395 .1638 .1903 .2082 .a 3.07 6.90 12.26 19.17 27.59 37.56 49.06 62.09 76.65 92.75 110.38 129.54 150.54 172.62 7. 14. 21, 28. 36. 43. 50, 57, 64, 72. 79. 86, 93. 100. 108, 201 402 603 804 005 205 406 607 808^ 009 201 411 612 813 014 Press- ure. Inches of water. .0005 .0021 .0047 .0083 .0130 .0187 .0254 .0332 .0420 .0518 .0627 .0746 .0875 .1015 .1166 Equiva- lent as T-t. deg^rees. Flow per hour, cu. ft. .41 1.64 3.69 6.56 10.24 14.75 20.08 26.23 33.19 40.98 49.59 59.01 69.25 80.32 92.20 5.272 10. 545 15,817 21.089 26.362 31.634 36. 906 42, 178 47,451 52.723 57,995 63,268 68. 540 73,812 79. 085 If the flow of air through a ventilating flue 40 feet high and one square foot in cross-section, as given in the two tables, is compared it will be seen that differences of temper- ature inside and outside the flue ranging from one degree to sixty degrees F. are associated with computed air move- ments increasing from some 8,000 cubic feet with a differ- ence of one degree F. to 63,000 cubic feet per hour when the difference in temperature is 60° F. ; while wind velocities ranging from one mile to nine miles per hour, acting by direct impact, and of two miles to twelve miles per hour acting by suction, give approximately equal rates of flow. If the actual velocities were one-half these computed amounts the slowest rate of movement would a little more 58 Ventilation. than meet the needs of one cow while the most rapid move- ment would permit a flue one square foot in cross-section to supply nine cows at the rate designated on page 41, 3,542 cubic feet per hour. Such a rate of movement, too, through a flue one-fourth of a square foot in cross-section would, at one half the slowest rate, supply air to 2 persons, and, at one-half the fastest rate, to 15 persons. The wind velocities which are effective in producing draft in dwellings and stables probably do not have a yearly average in most parts of the United States greater than four to six miles per hour. Taking the average flow due to impact equal to that computed for the four mile wind, and that due to suction equal to the computed value for a six mile wind, and supposing further that these effects are fully additive, the mean flow due to wind action would be some 60,000 cubic feet per hour, one-half of which may be lost in overcoming unavoidable resistance, thus leaving 30,000 cu- bic feet per hour of effective flow, which is sufficient to meet the needs of more than eight cows. The temperature difference effective in ventilation, not including heated chimneys, is perhaps not higher on the average than 20° F. for stables nor than 50° for dwellings, the first difference being capable of producing a flow of 36,000, and the second 58,000, cubic feet per hour in a 40 foot flue one square foot in section. If this motive power due to difference in temperature be added to that derived from wind action the resulting flow would be some 96,000 cubic feet of air per hour for stables and 120,000 for dwell- ings, having in mind theoretical flows and a ventilating flue 40 feet high and one square foot in section. Dividing these results by two, to allow for loss of power in overcoming re- sistance, the remaining motive power should be capable of producing a flow of 48,000 cubic feet per hour for stables and 60,000 for dwellings. In his * * Air Currents and the Laws of Ventilation ' ' Shaw cites experiments wherein the observed velocity of flow through 3-inch metal flues about 25 feet long varied from 7,482 feet per hour, when the wind velocity was at the rate Observed Air Movement Through Outtdkes. 59 of 2.5 miles, to 20,064 feet when the velocity of the wind was 15 miles per hour. The observed flow associated with a wind of 4 miles per hour in these experiments was 8,448 feet, and with 6 miles, about 10,000 feet per hour. At the 4-mile rate of flow a square- foot flue would meet the needs of only 2i adult cows, and the 6-miles rate, not quite 3 cows. In these trials all resistance is taken into account, the flows being actual, but in ordinary ventilation there would be added the temperature effect which might nearly double the efficiency. In the dairy stable of the Wisconsin Experiment Station, represented in Fig. 53, page 112, with a ventilating flue ris- ing 60 feet above the floor and with the main shaft 40 in- ches in diameter, the observed flow of air during one week was as follows: 1st day 205,377 linear feet 2nd day 205,800 linear feet 3rd day .247,852 linear feet 4th day 242,854 linear feet 5th day 151,974 linear feet 6th day 132,822 linear feet 7th day " 153,720 linear feet Here is an observed average velocity of air through the main ventilating flue of 7,978 feet per hour. In this stable, however, there are but 10 fresh-air intakes, each with an area of 3 by 12 inches and each of these is covered with a register face which reduces their efficiency to some ex- tent so that the aggregate area for fresh air intakes is less than 2.5 square feet. The walls and the ceiling of the stable are covered with galvanized iron and therefore prac- tically air-tight except for leakages about doors and win- dows. If all of the air passing through the ventilating flue had entered the stable through the fresh-air intakes the velocity through them must have exceeded 27,000 feet per hour which, with a flue one square foot in cross-section, would supply nearly sufficient air for 8 cows. In the four stables of H. McK. Twombly, Fig. 26, page 53, at his Florham Park farms, New Jersey, in July, when the cows were out after milking at night, with a wind move- ment outside near the ground less than 50 feet per minute^ 60 Ventilation. the rate of air movement was found to be as recorded be- low: Doors and win- dows open, per hour. Doors and win- dows closed, per hour. stable No. 1 feet. 11,040 7,740 8,340 8,640 feet. 8.620 Stable No. 2 7,860 Stable No. 3 9.180 Stable No. 4 6,960 Averag"e 8,940 8,160 The ventilating flues in these stables were 30 feet high, of galvanized iron ; 4.5, 3.5, 3 and 5 . 5 square feet respectively in cross-section, there being two for each stable. It will be observed that in this case the velocity of discharge through the ventilating flues averaged somewhat less with the doors and windows closed although the cross-section of the fresh- air intakes aggregated 6, 4.3, 4.6 and 6 square feet for the several stables, rather more than the cross-section of the ventilating flues. These intake flues, however, were covered outside and in with register faces which reduced their effective cross-section probably below that of the ventilators themselves. Under these conditions the available motive power for ventilation was probably near its minimum for the air near the earth's surface outside was alipost calm and the cattle were out of the stable so that the only avail- able heat for ventilation was the little that may have been retained by the walls to be given out during the night. Notwithstanding the low available motive power the wind movement through the ventilation flues was sufficiently rapid so that a current a square foot in cross-section was 2 . 5 times that needed for one cow. The influence of moisture as a motive power in ventila- tion is measured by the effect the amount transpired or otherwise added to the air has in making that within the space to be ventilated lighter per cubic foot than that out- side. Take the case of air outside at 30^^ and Aveighing .08107 pound per cubic foot entering a stable, becoming charged with moisture to the extent of saturation at 45^ Moisture as a Motive Foiver. 61 and having its temperature raised so as to remain at 50° when in the ventilating flue. Air so changed will be re- duced to a weight of . 07747 pound per cubic foot, thus giv- ing rise to a motive power in a ventilating flue 40 feet high equal to .027 inch of water/ and this pressure reduced to its equivalent value in temperature becomes 21.8° F.^ This value, 21.814° F., represents the combined effect of change in temperature and 'change in moisture content of the air. As the change in temperature between 30° and 50° is 20° the moisture effect must have a temperature equivalent of 1.8° F. This temperature equivalent, acting as a motive power, or aeromotive force, as it has been called, is capable of producing a theoretical flow in a 40 foot flue of 11,073 cu. ft. per hour.^ The motive power derived from moisture added to the air of a venti- lated space is always operative in assisting ventilation and its magnitude is the greater the more completely the air is saturated, the higher is its temperature and the longer the ventilating flue. In order, therefore, to most fully utilize the effect of moisture as a motive power in ven- tilation it is necessary to construct warm stables and to so place the ventilator that its walls may remain as warm as practicable, thus avoiding condensation of moisture before leaving the flue. It not infrequently occurs that the motive force due to wind pressure and wind suction is very small or even zero. We have found, for example, that at Madison, at the labor- atory very near the shore of Lake Mendota, where the wind movement was measured at an elevation of 120 feet above the lake and 82 feet above the ground, there were 16 days 1 (.081074 — .077472) X 40 .^^^ . , ^ — — -^ = ,0277 men water pressure 5.2017 .0277 X 491 X 5.2017 _ ^-^- — 4oor:o8io74 — - ^^-^^^ ^• ■^ 60 X 60 X 8 1 /^•^44 w ^Q = 11073 cubic feet per hour. 1/ 491 -^ 62 Ventilation, m January when during the night, the time when stables are most tightly closed, the wind velocity did not average five miles per hour during any 10 consecutive hours be- tween 7 p. m. and 7. a. m. On 10 of these nights the recorded wind movement during more than an hour was either zero or less than one mile. At such times as these dependence must be placed upon the motive power derived from rise in temperature and from an increase in the moist- ure content of the air after it enters the stable. It is im- portant therefore to know what the minimum motive power from temperature and from moisture changes is likely to be as this knowledge is fundamental in determining the proper dimensions for the ventilating system. As dairy stables will seldom need to be tightly closed when the outside temperature is above 30° F. and as at this temperature that of the stable is likely to be as high as 50° F. it may be assumed that the minimum motive power avail- able for the ventilation of such stables is likely ta be not less than that given when the outside air enters, saturated with moisture, at 30° and when the air leaves the stable at a temperature of 50° and containing only 3.3 per cent of air once breathed. Under these conditions the entering air would weigh .0809 pounds per cubic foot and before enter- ing the ventilating shaft would be reduced by changes in temperature and composition to .0777 pound per cubic foot, thus giving rise to a motive power in a ventilating flue 40 feet high equal to .02461 inch water pressure, whose equivalent, expressed in difference of temperature, is 19.422° F. This difference in temperature is capable of giving a flow of 36,227 cubic feet per hour through a ven- tilating shaft one square foot in cross-section and 40 feet high. This value is the theoretical flow. Taking the effect- ive flow equal to one-half this amount we shall have an hourly supply equal to 18,113 cubic feet or 301 cubic feet per minute. A velocity of 295 feet per minute in a flue 2 by 2 feet in cross-section will supply 20 cows at the rate of 3,542 cubic feet per hour and per head, and this is the amount needed, as previously stated, that the air of the Proper Dimensions of Outtake Flues. 63 stable shall remain 96.7 per cent pure or shall contain at no time more than 3.3 per cent of air once breathed, the stand- ard we have assumed as possibly permissible for dairy cows. In the case of barns for sheep, piggeries and especially poultry houses, where lower differences of temperature are quite certain to occur, the motive power must necessarily be less when the wind movement is small. Besides, in these cases, it will seldom be practicable to construct as long ven- tilating flues hence relatively larger shafts must be in- stalled or other equivalent means adopted for securing the desired change of air. To make clear this fact let us assume a poultry house for the accommodation of 50 hens each needing 35 cubic fee\ of air per hour, as stated on page 41. The vetitilating flus must therefore provide for 50 times 35 cubic feet, or 1,750 per hour. Let it be assumed that the ventilator has a length of 16 feet; that a temperature difference of only 4P is maintained in it when the outside temperature is 30° F. ; and that the rate of air movement is to be such as to main- tain a purity of 96.7 per cent with a moisture saturation at 34° of 90 per cent. With the outside air saturated at 30° and with the composition, page 13, its weight will be .0809 pound per cubic foot, and that in the ventilating shaft, at 34°, 90 per cent saturated and containing 3.3 per cent of air once breathed, having the composition of that stated on page 14, would weigh .08024 pound. This gives a difference of pressure between the air in the 16 foot shaft and that of an equal column outside of .00066 pound per square foot. Reducing this to its temperature difference equivalent it becomes ..2504° F. Using this value to compute the theoretical flow the result becomes 2601.3 feet per hour, which, at half this value, leaves an effective flow equal to 1300.6 feet. But the 50 hens re- quire 1,750 cubic feet of air per hour. The size of the ven- tilating flue must therefore be 1750 1300.6" : 1.346 square feet. 64 Ventilation. This area is given by a rectangular flue 14 inches on a side and by a circular one 15.7 inches in diameter. MAINTENANCE OF TEMPERATURE WITH AMPLE VENTILATION. It may appear that the movement of such large volumes of air through stables and dwellings as have been consid- ered needful in ventilation is incompatible with comfort and economy as regards warmth. Let us see what are the facts : In the first place we .need to understand that nearly all the food assimilated or utilized in the body, like fuel burned in the stove, gives rise to a certain amount of heat so that every animal and person is in a sense a heat gen- erating mechanism. It is estimated that a cow produces and gives oif from her body daily, as a result of changes taking place in the food she eats and air she breathes, an amount of heat equal to 76,133 British thermal units, heat sufficient to raise from 32° F. to boiling 423^ pounds of water and it is enough to raise the temperature of 79,603^ cubic feet of dry air from 0° F. to 50° F. Thus it appears that the heat generated by one cow dur- ing 24 hours is sufficient to warm approximately 79,600 cu- bic feet of air through 50 degrees F. or at the rate of 3,316 cubic feet per hour. This amount is only 226 cubic feet of air less than has been taken as possibly sufficient to meet the needs in dairy stables. It should be understood that during the winter in the United States only occasionally is the outside air at a temperature as low as 0° F. Indeed the mean temperature for "Wisconsin for January is nearly 15° and a rise of 50 degrees above this would give a stable temperature of 65°. Taking Doctor Jordan's estimate of the heat given off by a cow daily equal to 76,133 British units, and 3,542 cubic feet of air per hour as the amount needful for each cow, and supposing that the whole of the = 422.96 pounds of water, 180 2 76133 50 X .237 X .08071 = 79603 cubic feet. Temperature Maintenance with Ventilation. 65 heat so generated is lost through the air passing into and out of the stable, this heat is capable of warming the unit volume of air through 47.55 degrees F. and, on this as a basis, the following table is computed, showing approxi- mately the temperature of stable air when it enters at dif- ferent temperatures at the rate of 3,542 cubic feet per hour and per cow. Approximate temperature of stable- air resulting from animal heat, when entering at different temperatures at the rate of 3542 cubic feet per hour and per cow. Temperature of Temperature of outside air. inside air. — 32°F. 15.55°F. -10 37.55 47.55 10 57.55 15 62.55 20 67.55 25 72.55 30 75.55 Of course some heat is lost in other ways than through the air entering and leaving the stable so that lower tem- peratures than those in the table must be expected under the conditions stated but, as the average winter temperature in the United States is materially above 10° it is clear that good ventilation for dairy stables is possible and yet permit reasonable temperatures to be maintained. As a specific example of temperatures actually maintained the table which follows is cited, wherein are given the mean daily temperature of the dairy stable at the Wisconsin Agricul- tural Experiment Station, during two weeks, together with the outside temperature, the total air movement through the stable and the cubic feet of air per cow and per hour, as observed by E. L. Jordan in a thesis study relating to the influence of temperature on milk production. 66 Ventilation. Mean daily temperatures and air movement through a dairy stable containing 31 cows. Average Temperature. Flow of air. Date. Stable. Outside. Total per hour. Per cow per hour. January 13 56° F. 49 50 50 47 47 54 51 50 48 47 43 44 44 13'' F. 13 20 14 13 18 28 27 25 21 — 2 —18 —16 —11 Cu. ft. 83.621 86.965 80.591 83.522 85. 596 89.768 88, 435 81.578 105. 107 .92.317 83.479 77.632 81,882 100.964 Cu. ft. 2 697 Janu ary 14 2.805 January 15 2.600 January 16 2.694 January 17 2,761 January 18 2.896 January 19 2.853 January 20 2.632 January 21 3. .391 January 22 2.978 January 23 2.693 January 24 2.508 January 25 2.641 January 26 3. 257 This table shows that with the outside temperature rang- ing from 28° to -18°, a range of 46 degrees, the stable tem- perature varied between 43° and 56°, a range of but 13 de- grees, the temperature maintained entirely by the heat of the animals and this with a measured flow through the ven- tilating shaft at no time less than 2,500 cubic feet per cow per hour. In addition to this flow of air through the stable by way of the ventilator there was undoubtedly a material leakage through the windows and other openings which would carry the air supply well toward, if not above, 3,542 cubic feet, the standard assumed as possibly adequate. The amount of heat required for warming the needed amount of air for good ventilation is not as great as might be expected from its large volume for the reason that it is very light and because its specific heat is very low, only .237 as compared with 1 for water, pound for pound. That is, it takes as much heat to raise a pound of water one degree as it does to raise 52 cubic feet of air through the same range of temperature. With hard coal at $10.00 per ton and of the usual fuel value ; with the outside air at zero, to be raised to 72° inside, and supplying 10 persons during 24 hours at the rate of 537 cubic feet each per hour, only Little Extra Heat Needed with Good Ventilation. 67 11.26 pounds of coal would be required to furnish the needed heat, making the fuel cost but 5.63 cents per day for thus warming the necessary amount of air for 10 people. This statement must be understood as meaning that the ex- tra amount of heat in house warming required for proper ventilation is but very little above that required where only poor ventilation exists. Stated in another way, to main- tain the proper temperature in the house when the tempera- ture outside is zero, without any ventilation whatever, re- quires a certain amount of fuel, this varying with the type of construction. To warm the necessary amount of air re- quired for good ventilation during 24 hours would in real- ity cost less than 5 . 63 cents extra for 10 persons where coal is $10.00 per ton, because a part of this heat would also be available for maintaining the proper temperature. There is therefore little ground for providing insufficient ventila- tion because of extra expense needed for fuel. But in or- der that the maximum air movement through stables may be secured without the aid of artificial heat or mechanical appliances and that good ventilation for dwellings, schools and offices may be had without unnecessary cost it is im- portant that, so far as possible, the exhaust should be from the coldest part of the room which will be usually the floor level. There is a general impression that because respired air, before leaving the lungs at the temperature of 93° to 97° F. is lighter than pure air at room and stable temperatures it must rise at once to the ceiling and that for this reason ventilating flues should exhaust from that level rather than from the floor. The facts are that respired air so soon as it leaves the lungs and becomes cooled below 81° is heavier than pure air at the same temperature because of its increased content of carbon dioxide, the moisture it is capable of holding below 81° not being sufficient to com- pensate for the increased weight due to the carbon dioxide added. The fact will be made clear by an inspection of the next table. 68 Ventilation. Weight of a cubic foot of pure air and of air once respired iy man at different temperatures. Temperature. Pure air composition. O 20.61% CO 2 .03% HgO .55% N 78.81 Respired air composition. O 15.725 COg 4.350 HgO 2.000 N 77.925 70° .074316 .075223 64 Saturated 60 .075961 .077605 .079249 .080894 Saturated .076884 50 .078544 40 .080205 30 .081865 29.8 Here it is seen that air changed in composition by being respired and cooled to temperatures between 70° and 30° is heavier than pure air at the same temperature. As soon as respired air cools be- low the temperature at which it becomes saturated by its contained moisture a portion of this must be condensed, leaving it heavier because of this loss of moisture. Thus, in the colume of respired air, it is seen that it becomes sat- urated at 64° and' when it is cooled to 50°, instead of really having the weight there stated, on the basis that it could contain 2 volume per cent of moisture at that tem- perature, its actual weight when saturated is .078765 pound per cubic foot, which Fig. 28.— Inverted jar being is 1.49 per cent heavier than filled with respired air. ^^^^ ^.^ ^^ ^^^ ^^^^ temper- ature. Density of Respired Air. 69' That respired air, when surrounded by pure air, either rises very slowly or tends actually to fall may be clearly demonstrated. Let the Mason jar earlier used be inverted,. Fig. 28, while air from the lungs is made to displace that which it contains. With the candle already lighted let the jar be at once lowered over it, Fig. 29. The flame is ex- tinguished as it was in an earlier experiment when the candle' was lowered into the jar filled with respired air. But if the trials are now re- peated with the jar both in- verted and placed with mouth up it will be found, Pig-. 30. — Respired air soon drops from the inverted jar and the flame is not extinguished. Fig. 29. — Respired air in in- verted jar extinguishes flame if lowered over it quickly. Fig. 30, that with the in- verted jar materially less time is required ' for the respired air to become so changed as to permit the candle to burn in it than is the case when the jar stands mouth up. This could not be the case did not the rspired air, cooled by the walls of the jar, become quickly heavier than that outside. 70 Ventilation. These experiments and statements are in apparent con- tradiction to the results of some analyses of stable air, as in the case in the dairy stable at the New York Agricul- tural Experiment Station, represented in Pig. 31, where Dr. Jordan found, as an average of analyses made on two different dates, results given in the following table : Composition and temperature of air at the floor and ceiling of the dairy stable at the New York Agricultural Experiment Station. Ventilator working. Ventilator closed. Temperatvire of air. At ceiling' 56.3°F. 50.0 64.4°F. At floor 56.3 Difference 6.3 .4815 .7198 8.1 Composition, volume per cent. HgO at ceiling" .525 HgO at floor .5465 Difference .2383 .5335 .351 .0215 CO ^ at ceiling 1.4 CO, at floor , .... 1.0335 Difference .1825 .3665 These analyses of Doctor Jordan and those of similar im- port niade by other analysts appear to the writer not in necessary contradiction with the statements made, and that they should not be thought to indicate that it would be better for ventiltors to exhaust from the ceiling rather than from the floor level. In the case of the New York stable it appears probable that the circulation of the' in- terior air, as indicated by the arrows in Fig. 31, tends to •carry the respired air directly to the ceiling mechanically,- notwithstanding its greater weight, thus giving the ob- sei-ved distribution of products. It should be stated, to make the situation more clear, that the samples of air ana- lysed were taken at the center of the stable between the two mangers and where there must necessarily be a ma- terial mechanical effect tending to maintain an upward •current. Principles of Ventilation Construction. 71 But whatever may be the truth relative to the distribu- tion of products of respiration in dwellings and stables this we think, should hold in all good practice : Maintain a sufficient air movement through dwellings and stables to insure the entire air content in every case being sufficiently pure for thoroughly healthful conditions. It is hardly pos- sible to make the air movement for ventilation too large so long as the temperatures are right and there can be no doubt that the largest air movement with proper tempera- tures is possible only when ventilating flues exhaust from near the floor level. It is important to remember, too/ in this connection, that whether waking or asleep, whether standing, sitting or lying, the supply of air breathed must be drawn from near the floor level and that removing all air from this level compels the return of an equal volume to it. To fully utilize the heat of dwellings and stables in economic warming and in securing adequate ventilation it is imperative that certain principles of construction arid of admitting and of removing air should be adopted. Speak- ing here from the standpoint of stables, without artificial heat or forced ventilation, each animal must be regarded as a heater which is warming the air of the compartment in three ways: (1) by direct contact of the air with the body; (2) by rapidly breathing large volumes of it and raising its temperature at once to between 93° and 97° F. ; (3) and by direct radiation of heat to_ walls, ceiling and floor which in turn warm the air by contact. Because the warmed air is thus rendered lighter it is forced at once to the ceiling where it tends to collect, while the coldest air, settling toward the floor, gives rise to an internal system of circulation represented by the arrows in Fig. 31. It will be seen from this illustration that the circulation of the stable air is maintained by the continuous action of three motive forces; (1) the waste heat of the occupants which becomes effective through its expansion of the air; (2) the mechan- ical or bellows-like action of the chests of the cattle and (3) the loss of heat by conduction through the outer walls. 72 Ventilation. Referring to the figure the arrows show that from the bodies -of the cows convection currents rise directly toward the ^'-- ^ > ^u^ / :iv&^::?.>M^¥'>:' "'^^''iL' 1 ^ 1 ^ 1 1 in 1 ^ 1 ^ 4 ^ E=t 1 ^ 1 m m 1 ^ 1 1 ^ i "^ % m Dl 1 ^ 1 1 '^ 3 S ■ 1 - ^ 1 ^ Fig. 31. — Section of cattle barn at New York Agricultural B'xperiment Station. I, illustrating convectional system of air currents main- tained by the animals and the cooling of the outer walls. II, side elevation of stable viewed from inside, showing AA, floor entrance to ventilating flues; BB, ceiling openings to ventilating flues; GGG, ceiling openings to fresh air ducts; WWWWWW, windows, and DD, doors^ III, side elevation of stable viewed from outside showing GGG, openings to fresh air duots. ceiling; that with the cows facing each other the bellows- like action of each row forces the air currents so formed to meet in the center and the air must rise and then flow out- ward along the ceiling in both directions, finally descend- ing along the outer walls, at the same time mixing with the incoming fresh air entering at the several intakes GGG shown in the side elevations II and III. During cold weather and especially at the windows, unless they are double, and all along the walls if not of wood or hollow masonry, so as to be poor conductors of heat, the air will be cooled, thus rendering it heavier, causing descending currents which must flow along the floor, maintaining a more or less strongly marked system of air circulation within the stable, which tends continuously to mix the re- spired air with that entering from without. Principles of Ventilation Construction. 73 From this tendency to the formation of a continuous cir- culation of air within the room to be ventilated it is clear that it must be extremely important that both ceiling and walls should be air-tight and warm in construction. With ceiling and walls tight and poor conductors of heat and with no opportunity for air to enter except where special provision is made, near the ceiling at GGG inside, II, Fig. 31, or for it to escape except at the' floor level, only the coldest air is permitted to leave the stable, while at the same time the fresh air must be mingled with the warmest air of the stable, thus having its temperature raised before reaching the animals. Where such conditions of construc- tion are secured the whole ceiling and upper walls become a continuous radiator of heat, sending back to the animals and to the floor, where it is most needed, the heat which has escaped from them. By admitting the fresh air from low do\^Ti outside and at the ceiling inside, as represented in Fig. 32, this air entering from all sides as shown by the large arrows in Fig. 33, the cold incoming air is thus widely and generally mixed with the warmest air of the stable, thus having its temperature raised before being brought to the animals ; while with the ventilating flues opening at A, Figs. 31 and 32, near the floor level, this arrangement not only compels the coldest air to be removed but it forces a return of the warmest air in the stable, mixed with the fresh air from outside, and thus partly warmed, to the floor level where it is needed both for warmth and for respira- tion. So, too, in the ventilation of dwellings, offices and' school- houses, as represented in Figs. 44 and 48, by admitting the fresh supply of air at the ceiling, where the highest temperature exists, not only is the heat being lost by up- drafts through leaks utilized to warm the incoming air, but all drafts are avoided near the floor level, thus making it possible to have maintained the maximum air movement through the rooms without danger or discomfort. 74 Ventilation. Eeferring further to the method of admitting fresh air to stables, illustrated in Fig. 31 and 32, it should be un- derstood that the position of the outside openings for the entrance of air to the fresh air ducts, placed at some dis- tance below that admitting the air to the stable, is funda- mentally important for the reason that only in this way can the escape of the warmest air of the stable through '■if^T^Tf Fig. 32. — Section of dairy stable showing tlie action of the wind at DD, forcing air into the stable by direct pressure at BB and out of it by suction at the top of the ventilating shaft AA, At C is a ceiling register in the ventilating shaft to be opened only when the stable is too warm or when the draft is too feeble. such openings on the leeward side be prevented. Without some such provision as this the case would be like lowering the windows at the top on opposite sides of stable or room, which always results in fresh air entering on the windward side and warm air escaping on the other. With the ar- rangement adopted, as shown in the illustrations, only a strong wind pressure can result in forcing the warm air to descend and escape through intakes on the leeward side. Principles of Ventilation Construction. 75 The ventilation of offices which is so often attempted by raising a window at the bottom and inserting under it a screen carrying a pair of short Tobin tubes, like up-turned pipe elbows, while better than no attempt, can seldom give adequate ventilation where steam or hot water is used for warming for the reason that here provision only is made for air to enter and this can take place no faster than Fig. 33. — Floor plan of dairy stable, Fig. 32, showing fresh air intakes on all sides at the large arrows crossing the walls; two ventilating flues are AA and the air approaching them along the floor level indi- cated by the small arrows. opportunity for escape exists. The opening of the door into a hallway or of the transom above it usually has only the effect of making the box to be ventilated larger; and the result usually is, with such makeshifts, that, on windy days during cold weather, such window openings are closed to save heat and during still weather there is little motive power to force an air movement if they are opened and hence much of the time very inadequate ventilation must obtain. PEACTICE OF VENTILATION. In coming to the practice of ventilation in cold -climates the problem is reduced to its lowest terms when it is stated that the desired results can be ideally secured only when the construction of the building to be ventilated is such that no air can enter or leave it except at appointed places, and when all heat is lost through the outgoing air and none, or as little as possible, through the walls. While it is not practicable to construct enclosures whose walls are either air-tight or perfect non-conductors of heat it is ;nevertheless of the highest importance, as leading to correct practice, that right ideals be held and that they effectively direct construction. When nearly all air enters and leaves the space to be ventilated at the appointed places and when most of the heat is borne away during cold weather by the air leaving the room or stable there is secured the largest practicable rate of change and the most thorough ventila- tion, which is the object sought. Life under these condi- tions may live to its fullest capacity, rather than survive by the narrowest margin. BEST ROOM AND STABLE TEMPERATURE. The fires of life, kept alight through all the organs of the body by the incessant fanning of the lungs and the tireless pumping of the heart, can only be maintained between very narrow ranges of temperature. With ourselves and with all our domestic animals the temperature within the body lies close to 100° F. If the general active tissue tempera- lure falls but a few degrees below this life activities must Best Boom and Stable Temperature. 77 cease; within the healthful but narrow range chemical changes go forward along normal lines and at the normal rate ; at but a few degrees above this temperature reactions occur which seriously interfere with body functions, mak- ing them abnormal or causing them tO cease. Since most of the activities within the normal body re- sult in the generation of more or less heat, and since the in- ternal temperatures must be kept near 100° F., it is clear that surrounding temperatures must be at some lower de- gree than that of the body in order that a rate of loss of heat equal to that of production may take place. In our own case we become uncomfortable when the surrounding temperature rises much above 68° to 70° and the same is true of our domestic animals. Stables and dwellings then, as a rule, should have a temperature lower rather than higher than 70°, but how much lower than this is best must depend upon various conditions. Persons engaged in bodily exercise, and animals being heavily fed, like fatten- ing swine, steers or sheep, are likely to do better in some- what cooler quarters, (1) because the greater activity as- sociated with increased assimilation must develop more heat and this must be removed at a more rapid rate, and, (2) because the aim in feeding such animals is to induce them to eat as much food as can be economically converted into the products sought, too warm quarters tending to make the need and desire for food less. It has been found that when fasting and at rest, under a temperature of 90°, a man consumed some 1,465 cubic inches of oxygen per hour, but under the same conditions except that the surrounding temperature was 59°, 13 per cent more oxygen was consumed and a like' increased volume of carbon dioxide thrown off, thus showing that more food must be eaten to compensate for the increased waste. But in eating more to maintain animal heat under lower tem- perature surroundings it is probable that more than enough to do this may be taken and hence that an increase in the formation of useful products will likewise result. When animals are simply on a maintenance ration and the aim is 78 Ventilation. to carry them with the least amount of food their quarters should then be as warm as the demands of health will per- mit. It seems likely that the best temperature surround- ings for animals being fed high will be found to lie. between 45° and 50°, while with animals on- a maintenance ration these will be found to do better and to be maintained at a lower cost under temperatures between 55° and 65°. ^Mth dairy cows, having large udders only scantily clothed with hair, and through which so much blood must flow, it may be expected that a temperature perhaps as high as 50° to 60° will be found best, even with high feeding, although the few studies known to the writer, which have been made to determine this matter, have resulted in inconclusive data. Because full comfort and complete satisfaction; ample and appropriate food and drink properly supplied; and sufficient unimpoverished and unpolluted air all of the time are the indispensable requirements for the highest ani- mal production, and because we have never known an ani- mal, however well fed, to voluntarily take to the open field in cold weather for rest, we are not yet convinced that a conveniently arranged and sufficiently warm shelter ade- quately ventilated is not indispensable to the highest results from winter feeding and winter maintenance. LIGHT FOR DWELLINGS AND STABLES. In the construction of every dwelling much care should be taken to secure an ample amount of light, in the kitchen, in the dining room and above all in the main living rooms. An abundance of light is needed not only to facilitate work but to make the best of intentions more certain in at- taining results. Besides, it requires an effort to be gloomy and feel ugly in the face of a hearty laugh and a bright sunny, cheerful room has much the same effect upon those who occupy it. Many disease germs are enfeebled by di- rect sunshine or are destroyed by it. Who has not ob- served the cat deliberately seek out the sunny spot on the Light for Dwellings and Stahles. 79 carpet for the good feeling that comes with it and lasts after it. A sunny window is equally needed and enjoyed by the members of the family whose duties confine them so exclusively to the house. The number, size and exposure of windows best suited to the requirements of dwellings and stables is not well established either in philosophy or in practice. It should go mthout saying, however, that sufficient window space must be provided to admit ample light for doing all necessary work with dispatch and efficiency and with- out an undue strain upon the eyes. How far beyond supplying such an amount of light it is best to go there is yet much room for difference of opinion, owing to the present state of knowledge, as to the efficiency of light of different intensities, as to the best manner of ad- mitting light to dwellings and as to its importance in dwell- ings and stables as an agent in sanitation. So much is being urged upon the public at the present time, especially in the matter of lighting dairy stables, as a necessary measure of sanitation that it becomes a matter of practical moment to have the problem clearly and correctly stated, and the more so because efforts to secure unsual lighting are very likely to lead to deficient ventilation in dwellings and stables in all cold climates. It has ever been and it must always remain true that the life resultants of every type are necessarily attained through compromises. Nature has never been an extremist along any line and all of her biologic assets have accrued through admitting in partial potency the multitude of fac- tors always operative in securing the result, whether that be maa, stamped with the highest attainments, or the dead- liest microbe pitted against him. And so we are here con- fronted with the problem how much of light is most whole- some in the dwelling, and how much light may be admitted without unduly curtailing other essential requirements. In the effort to put into practice the deductions of re- search and the recommendations of zealous but not always sufficiently informed teachers of stable sanitation many ser- 80 Ventilation. ious mistakes in construction are being made, one of which is illustrated in Fig. 34. This stable is far from the best type for use in cold climates. Thus constructed, the short, low closely-capped ventilators tend in themselves to provide but a small air movement. Then with the row of hiq-h deck Fig. 34.— Showing faulty arrangement of windows for stables in cold climates, the effect being to render them cold and damp, windows there is provided an elevated ceiling space into which the warmest air of the stable immediately rises, car- rying with it the heat of the stable beyond where it can be utilized in warming the incoming fresh air, and where, be- cause of great hight and unavoidable leaks, much of this warmest air must escape through the roof, tending further- more to even carry fresh air direct from the intakes along the ceiling and out through the ridge, thus diminishing the lower ventilation. Such a stable, unless artificially heated, must either be very cold or have a small air movement through it. In either case the air must be damp and for this reason unsanitary. The side windows in this stable are excellent, both in dimensions and exposure, but, in our judgment six or seven, instead of ten, on a side, would have been ample. If it shall be proven imperative to admit more direct and sky light into stables for the purpose of disinfection then some type of construction embodying the principle Lighting of Stables, 81 represented in Fig. 35 must be adopted. In a type of con- struction like this, with double windows arranged along the slope of the roof, and with similar windows in the side both direct sunshine and reflected light from the sky may be ad- mitted to the stable from all zones to the greatest practi- cable extent and at the same time utilize the animal heat in keeping the stable warm, thus permitting a maximum flow of air through the stable without unduly lowering its temperature or rendering.it damp. p^ Fig. 35.— Cross-section of a concrete one-story dairy stable de-igaed to admit tlie maximum amount of direct sunshine and of diffused liglit from the whole sky, leaving it at the same time warm in construction so as to permit the maximum air movement thus combining sunlight and desicca- tion to the greatest practicable extent as disinfecting agents. It does not appear likely, however, that such extremes of illumination for either dwellings or for stables will be found materially better than moderate window space con- fined to the walls. It will not be maintained that, even out of doors where direct sunshine is at a maximum both in intensity and in duration and where the full hemisphere of reflected light from the sky is added, bringing illumination from every side, all disease germs which may there be present are destroyed by the light. Faced by this general truth relative to light as a destroyer of disease germs it be- comes clear that even glass houses and stables cannot be ex- pected to eradicate germ diseases. In dwellings and stables, far more than out of doors, shadows cast by litter and fix- tures must effectually baffle all efforts to secure anything more than partial disinfection through the action of light whether coniing direct from the sun or reflected from the 82 Ventilation. sky. The greatest safeguard against germ and all other diseases is found in a well nourished and well eared fot body and as more than the half of such indispensable nour- ishment must be pure air, lighting beyond a fair amount cannot be permitted to seriously interfere with the air sup- ply of stables or dwellings. Dr. Weinzirl, of Washington University, whose has made recent critical studies along the line of light as a destroyer of disease germs and particularly those of tuber- culosis, wrote, under date of Feb. 17, 1908, as follows: **In reply to your question as to the value of sunlight in stable disinfection and the feasibility of this method I will say that in my opinion sunlight is of little value and prac- tically of no value under prevailing conditions, nor do I believe that it can be made valuable by merely increasing the amount of diffused light through side windows. I ex- posed tubercle cultures on the window sill on north window for a week and yet about one-half of them grew. As to the other half I am inclined to think that desiccation, and per- haps other factors, entered to kill the culture. At any rate non-spore bearing bacteria are more readily killed by dry- ing than is generally believed. A day or two will suffice to kill many of them. ' ' In another letter Dr. Weinzirl qualifies the views as above expressed, writing under date of Oct. 19, after the other was in type. He says: "I have made a good beginning on the problem of im- portance of diffuse light and as a result of this work I have to revise my views quite materially. The shortest time in which diffuse light in a room killed the bacillus of tuberculosis was less than a day and the long- est time was less than a week; generally, three or four days of exposure killed the organism. Some pus-producing bacteria required a week's time to kill them, while some intestinal bacteria were killed in a few hours. It was also found that bacteria are killed more quickly in a moist air than in a dry one, contrary to general belief. Sanitary Effect of Light. 83 The diffuse light as found in our dwellings is, therefore, a hygienic factor of great importance, and where direct sunlight is not available, it should be carefully provided for.'' It may be added as supplementary to Dr. Weinzirl's let- ter just quoted that he also made at the same time control exposures in the dark which showed, for the six groups of trials made between March 3 and July 2, and on as many dates, that no growth took place after intervals varying from 2 to 10 days, the exact times after which all germs were dead, or after no growth was observed, being 10, 7, 8, 9, 2, and 5 days respectively while the corresponding times for the diffuse light were 5, 3, 5, 6, 1, and 4 days. The averages of these two groups of intervals stand in about the ratio of 7 to 4, which means that under the conditions of exposure adopted and the method of testing viability the life of tuberculosis germs was rather less than 4 days in diffuse room light and that in the dark their life was less than 7 days. But it would be very misleading to leave light as an agent of disinfection with the reader thus stated. It should be understood that direct sunshine is far more potent in destroying disease germs than is reflected light and that that from the noon sun is stronger than the light coming from it earlier or later in the day. Most im- portant of all to remember, for the direction it should give to practice, is the fact that even in the brightest sunshine the slightest shadows materially cut down its power to de- stroy germ life, so that under the hay and bedding of the stable and especially in the dung, where germs may abound, effectual darkness may obtain where the direct sunlight of noon is falling. Here is the kernel: Utilize to the fullest practicable extent every available agent of destruction, but remember that in every infected stable and home although millions of germs may be destroyed multitudes will escape and the losses will be made good from the springs of life. Remember, too, it is within the body, where effective dark- ness always prevails, that injury is done if it is powerless to resist, hence no amount of sunshine can compensate for the 84 Ventilation. diminished bodily vigor which results from insufficient ven- tilation, or other food supply. It is important to understand something of relative in- tensities of the light received from the sky from different quarters and of that direct from the sun compared with that from the sky. Dr. C. G. Abbot of the Smithsonian In- stitution and Director of the Astro-physical Observatory, has determined the relative intensities of sky light coming from different elevations above the horizon from Mount Wilson at the time of clear sky in August and September with results given in the table below : Average brightness of the sky at different distances above the horizon. Altitude. Eelative intensity. 0° to 10° 460 4.00 10 to 20 210 1.82 20 to 30 185 1.61 30 to 40 150 1.31 40 to 55 128 1.11 55 to 75 122 1.06 75 to 90 115 1.00 This table makes it appear that windows taking light from near the horizon may receive nearly four times the amount of that coming from directly overhead supposing the windows vertical in the first case and horizontal in the second and no obstructions whatever in either instance. As to the relative intensities of sky light coming from the south, east, north or west Dr. Abbot writes as follows under date of Oct. 28, 1908 : ' ' I regret that our observations on the sky have not been conducted excepting on Mount Wilson, and that they are scanty even there, so that my replies to your questions can- not, I fear, be very satisfactory to you. I feel sure that most light will be received from the sky if the stable windows face south (obstructions of course be- ing absent). East and west will be nearly alike in this re- spect, but in most sections west will receive more than east. North is least favorable. Less sky light will be received at high altitudes above sea level and at very clear localities than at low and hazy sta- tions. The horizon is much brighter than the zenith so that Intensity of Sky Light. 85- where trees and hills do not obstruct the view the windows would receive most light I suppose if they w^ere horizontal rather than* vertical in their longer dimensions. I incline to think that horizontal windows adapted to receive light from the horizon to 30° altitude with unobstructed south- ern exposure would receive as much as four times the light equally large vertical windows with north exposure and adapted to receive light from 30° to 90° altitude would admit. But this is not a computation and is not applicable to all latitudes and altitudes above sea level, but is only intended as a probable estimate to suit average conditions in the United States. In winter the advantage of horizon- tal southern windows is greater than in summer. As to the disinfecting qualities of the sky light at dif- ferent zenith distances I know nothing. It seems prob- able to me, however, that if any such qualities exist in zenith sky light they would be found in at least equal and probably in greater total amount (not percentage), in the horizon sky light. I do not know whether the disinfecting properties of light are cumulative as the photographic action is, or far greater if the light is very intense like the rise of temper- ature of a body in the focus of a lens. If the former is the case I should have little question that the continued action of sky light would be preferable to the brief action of sun- light. The whole sky at sea level is apt to contribute nearly as much light as the sun, and by far the larger proportion in middle northern latitudes comes from the southern half of the sky. The above opinions are presupposing a generally clear sky. If the sky is most of the "time cloudy, southern ex- posure would still be preferable but the horizon would, I think, cease to be the best part of the sky." If Dr. Abbot's views thus tentatively expressed shall be found correct stables and dwellings should be lighted as far as practicable from the south for the reason that both direct sunshine, in the middle north latitudes and the max- imum amount of sky light may thus be obtained. In the- eastern part of the United States, east of Kansas, the aver- 86 Ventilation, age per cent of sunshine, computed on the total possible, is near 56. Taking this in connection with the fact that generally a considerable portion of the horizon to an alti- tude of 10° is obstructed we are inclined to favor windows with their long dimension up and down. The diiference will be made clear from a study of Fig. 36, where it is seen that the point A on the floor receives sky light through the window E from between 20° and 50° above the horizon while from the window W, having half the vertical height, light comes in between 20° and 35°. If the lower light is most intense the last window will admit the most sky light, but if the higher light is best then the former window is to be preferred, from the standpoint of sky light. With the high window, as seen at C and B, direct sunshine must sweep a materially broader floor area than if it- is short. Fig. 36. — Influence of higlit of windows on the admission and distribu- tion of liglit in a building; B, C, area of direct sunstiine; heavy arc of circle subtends angle of diffused light falling at A. In low stables with wide overhanging eaves, and where windows are under porches, the same area of glass admits very materially less light, as is evident from an inspection of Fig. 37. The overhanging eaves at A, it will be seen, cut out half the direct sunshine and at the same time ma- terially prevent the entrance of diffused light from the sky. From the other side of the building, where the eave does not overhang so far, both the quantity of direct and of re- Efficiency of Windows. 87 fleeted light are seen to be materially increased over that entering the opposite window, as shown by the length of Fig. 37. — Effect of overhanging eaves and porches in reducing the effi- ciency of windows. the direct sunshine areas D and E and by the size of the angles of diffused light falling at the point C. It should be remembered too that where the walls of a building are thick relatively larger windows are required to secure the entrance of the same amount of light, the fact being made clear by a study of Fig. 38. The window at F, Fig. 38.— Showing the effect of thickness of wall in reducing the effi- ciency of windows. four feet high in a wall one and a half feet thick, has its direct sunshine efficiency reduced nearly one-fifth by the thickness of the wall, as shown by the area marked H,. SS Ventilation. ** sunshine cut out/' with a width for this window of three feet, as shown at A, and with a thickness of wall of 18 in- ches, the angle at which sky light may enter is reduced from 180-^^ to 128^,- while a wall of half this thickness re- duces the angle for dithised li^ht only to 150^. AYith larger windows for the same thickness of wall the percent- age loss of efficiency is less. In the case of direct sunshine the drawing represents the smallest possible reduction with the sunlight entering at the angle represented, the building l)eing supposed to face the south with the sun at noon. At any time before or after noon, with the same altitude of the sun, a still greater reduction than that represented must take place. VENTILATION OF DWELLINGS. It is safe to say that before the close of another hundred years a very large proportion of the dwellings now in use will have been entirely rebuilt or extensively remodeled and that it is now none too early to begin a campaign of education which shall lead to the rebuilding or remodelling of those dwellings along lines which will make them thor- oughly sanitary, convenient, pleasant and capable of being economically maintained in all of the ways which can con- tribute to substantial home comfort and character building. It is also safe to say that at least two more generations will be compelled to grow up in the dwellings now in use but which are far less sanitary, from the standpoint of ade- quate ventilation than were those of the grandparents of the children now sixty. Then, in whatever other ways those homes may have been deficient, there was continually moving through them an abundance of undiluted and un- polluted air. The wide-open throat of the great fireplace of those days, which never could be closed, Avas everlast- ingly sucking out of the few rooms and in through the chinks in the wall, great volumes of air such as few people living in modern dwellings can realize. Today, with win- dows double; with walls sheated inside and out, sided, plastered and papered, on retiring we close everything Ventilation of Dwellings. 89 tight, even to the heater and kitchen range, and wake the next morning from troubled slumber hoping that, whatever else may not have been for the best, we have at least saved a little of the $9.50 per ton coal. Clearly if the two gener- ations which must dwell in the old homes can be led and helped to better conditions of living in them great present and future gain will result. The vast throng of victims annually and prematurely wilting and fading away before the dreaded white plague meet disaster, not so much be- cause of the great numbers and wide-spread distribution of the disease germs, as because of the terrible prevalence of such living conditions for cattle and people alike as convert the weak among them into hotbeds for the breeding of tuberculosis germs. Disease-germ-bearing milk is only one of a thousand vehicles by which these germs are spread and helped to gain a new foothold. If we shall ever succeed in greatly reducing the numbers of its victims it must be through fortifying the individual, rendering him capable of resisting the development of the disease germs even if they are introduced into the system, and this must come through more wholesome conditions and habits of living. It cannot be too forcibly impressed upon the manage- ment of households that when one's duties are such th^>t much of the time is spent in the open air, or that one is out and in frequently, the consequences that follow inadequate ventilation are likely to be far less serious than upon those confined more exclusively to the house. It should be re- membered too that the person whose system has just been thoroughly renovated by breathing an abundance of fresh air is less sensitive to, except for the moment, and can safely endure, degrees of air pollution which may be oppressive and dangerous to those continually confined to inadequately ventilated rooms. And so it often happens that the menfolk of the farm are living fairly well, while the women in the same home may be suffering severely, -especially during the winter, for lack of proper ventilation. Thought and judgment, therefore, exercised in the house as well as in the barn, is necessary. 90 , Ventilation, Ventilation of Houses Already Built. When the heating of the house is by means of stoves placed in the living rooms a certain amount of ventilation is secured through the direct action of the stove, for all of the air which enters the stove and leaves the room through the chimney is drawn into the house, through chinks in the walls where no special provision for entrance is made, and so long as the draft of the stove is open there may be suffi- cient ventilation for the time but so soon as the draft is closed and air ceases to escape through the stove, inade- quate ventilation is likely to result. Suppose it is in the evening and five of the family are gathered about the table in a room 15 by 15, with a 9-foot. ceiling and that they are using a lamp whose power to vitiate the air is equal to that of 10 candles such as used in Fig. 13. There would then be a consumption of air in the room equal in amount to that demanded by nine or ten people. We have found the ordinary student-lamp to burn kerosene at the rate of 38.4 grams per hour and this demands oxygen equivalent to more than six people, so that it is safe to say that, with five people and such a lamp, air is needed for the equivalent of ten people, and this demands an air movement, to maintain the standard of purity which we have assumed as possibly permissible for dairy stables, equal to 5,370 cubic feet per hour, which requires the room to be emptied of all its air and refilled once about every 22.6 minutes. It will be readily seen from this statement of fact that whenever the room becomes a little too warm, so that the drafts in the stove are all closed, such a room, not otherwise ventilated, would very soon become unsanitary from the standpoint of pure air. Indeed, with no interchange of air, in one hour nearly one-tenth of the whole air of the room would have been used once, and in once-breathed air we have seen the candle extinguished. Let us see now what the stove can do for us in the way of ventilation when the drafts are open. Suppose the Combined Heater and Ventilator. 91 chimney is 30 feet high and the air in the chimney is main- tained at a temperature 50 degrees above that of the air outside'. From the table, page 56, the theoretical flow through a one-foot square chimney 30 feet high is 50,472 cubic feet per hour. With half this efficiency, to allow for resistances to be overcome, and taking the cross-section of the 6-inch stovepipe through which the air must all go, at . 2 of a square foot, the air movement which could be main- tained is at the rate of 5,047 cubic feet per hour, which is a little less than 5,370 cubic feet, the movement we have as- sumed as possibly permissible. This reasoning and calcu- lation makes it clear that whenever a room thus ventilated has the drafts in the heater closed the necessary air move- ment must at once fall below good living conditions and hence that some provision ought to be made for keeping up the air supply whenever the heater is not running with open drafts. There is often a check-damper in the stove- pipe or stove which may be opened when the drafts are closed and so partly, at least, keep up the air movement. Such openings, however, as usually placed, are wasteful of heat because they throw out of the room only the warmest air. To economically use the room heater as a ventilating device there ought to be attached to the stovepipe, as rep- resented at C in Fig. 39, a section extending down to near the floor level, provided with a close-fitting damper, so that whenever the drafts are closed in the stove the damper in the ventilating section may be opened, and thus keep up the air circulation, drawing out of the room only the cold- est air it contains. Here, then, is a simple arrangement by which many a poorly ventilated home may have its sani- tary conditions very materially improved, at a trifling ex- pense when compared with the advantages gained. If the room to be ventilated is tightly constructed and if air can- not be borrowed from another unoccupied room by leaving the door ajar, there is no reason why fresh air intakes may not be provided on the same plan as has been illustrated for dairy stables in Figs. 31-32, pp. 72-74, and which is rep- resented at AAAA, BB, in Fig. 39. In providing such in- 92 Ventilation. takes it is only necessary to make openings through the sid- ing, as represented at A, between pairs of studding, cover- ing them with one-eighth inch mesh galvanized wire net- ting, and make corresponding openings just under the ceiling at the same pair of studding, covering these with white enameled 4 by 12-inch register faces. Pig. 39.— Improvised ventilation system for an ordinary dwelling already built. The proper course to take in installing such a ventilation system is to modify the heater so that air may be removed from the floor level as already described. If it is then found that an air change of sufficient rapidity takes place, this being made possible through unintentional openings in the wall, the desired result has been attained and the in- takes need not be provided. It may be that a sleeping room :' situated as represented in the illustration, through which the stovepipe passes. If so it is a simple matter to attach .a radiator to the pipe and thus without extra expense ma- Heating ivith Warm Air and Ventilation 93 terially warm the room and improve its ventilation if only a ventilating fine is installed as indicated at D. In this case we have assumed that there is a partition and that the space between a pair of studding may be opened just above the baseboard and covered with a white enameled register face, or better still, a register which may be opened and closed, and then open this space into the attic or, what would be much better, extend up through the roof a six- inch galvanized iron pipe, connecting this with, or extend- ing it down into, the space between the studding leading to the ventilating register. With such an arrangement, with the fresh air intakes indicated in the figure and with the radiator as shown, we have an ideal sleeping room or, if the heater below is large and the room above small and warmly built, it may be a comfortable sitting room with- out the expense of additional heat. Dwellings that are heated with hot air furnaces, if they are thus sufficiently warmed, are usually amply ventilated so long as the warm air is being forced in, unless the faulty arrangement has been adopted of returning the air from the heated rooms to the furnace to be revolved over and over again. Such a system is very bad and should never be used unless it be in faultily constructed houses where there is excessive air leakage through the walls or in windy weather when the temperature is excessively low. In steam-heated houses and in those heated with hot water by means of radiators distributed in the rooms to be heated the ventilation may be, and usually is, extremely deficient, much more so than with stove-heated rooms, for the reason that with these systems of heating there may be provision neither for air to enter nor leave the room, dependence be- ing wholly upon leakage through the walls or upon the opening of windows and doors. In houses thus heated some means should be adopted for drawing the air out of the rooms at the floor IcA^el, even if nothing better than the plan suggested for the second floor in Fig. 39 at D. Fresh air intakes should also be provided and if possible these should be so placed that the air may be admitted at the 94 Ventilation. ceiling directly above the radiators, of course admitting the air from low down outside, as at A B, Fig. 39. "When the fresh air intakes are thus located the currents of warm air rising from the radiators at once mingle with the fresh air entering, so that this is immediately and directly tem- pered. Of course very many variations will occur in mak- ing the necessary provisions for the ventilation of houses already built but enough has been said to permit such adaptations as may be called for. Warming and Ventilation for New and Remodeled Houses. As has been earlier said the real problem with which we have here to deal is, how nearly can we maintain the air of dwellings at the normal out of door fresh air purity with practicable economy. Accepting this statement as correct it follows that if pure air itself can be economically warmed and used as the medium for distributing heat through the house it by all means should be used, rather than water, as such, or in the form of steam. All but two of the twenty- eight years of our home-making have been spent in two eight-room houses, each with two stories with a cellar and a floored attic, full size. Both were of wood with walls of 2 by 4 studding covered with tongued and grooved fencing inside and out; papered and sided outside and lathed and plastered inside. The space between every pair of studding was ceiled at each of the three floors to prevent the circula- tion of air currents between rooms and attic due to leakage through walls and ceiling. The windows were all made with single sash but double glazed, except three in the sec- ond house, which were of plate glass. Each house has a single chimney beginning in the cellar, with three flues, the central one 12 by 12 inches, for the furnace and kitchen range, and two, one on each side, 8 by 12 inches for ventila- tion. Both houses are warmed with hot air, the whole lower floor except the front hall being maintained at 64° to 68° eighteen hours per day. Plants have been grown continu- ously in bay windows and on window brackets in both Heating with Warm Air and Ventilation. 95 houses and these have never been frosted, they have never been moved from the brackets to prevent freezing, the only precaution taken being to draw the curtains, and the fur- nace has never received attention nights after retiring, usually about 11 p. m. The first house was warmed more than fifteen years with a single cast-iron box stove, using four-foot wood, which was provided with a drum of sheet- iron and bricked in like a furnace. The second house is warmed with a No. 10 Economy furnace having a metal shield and using coal. The fuel bill for furnace and kitchen range in the first house ranged from $55 to $75 per annum, In the second house it has ranged from $64 in the earliei years, increasing with the price of coal, to $95.50 in 1908, using hard coal with some wood in the range, and gas coke at $6.75 per ton, and ''buckwheat" coal at $6.50 per ton, burned together, in the furnace ; ' ' chestnut " at $9 per ton for the kitchen range. From this practical experience, cov- ering a continuous quarter century of Wisconsin climate we feel justified in saying that in a warm, well-constructed house it is entirely practicable to economically warm an eight-room dwelling by distributing the heat with warm air, which at the same time serves the purpose of thorough ventilation. We think we are also justified in saying that if there is ever an investment that pays it is the little extra required to build a house for a cold climate" Avarm, well and thoroughly ventilated, if your own family is to live in it. The saving in fuel alone is high interest on the extra money invested and you get the healthful conditions and comfort free. But we would not advise hot air warming for a house poorly constructed. Rooms provided with fire-places may be well ventilated but seldom economically warmed. Steam and hot water are well adapted to heating all types of dwellings but the cost of installation and that of maintenance, excepting for fuel, is relatively high. Good ventilation may be provided with both hot water and steam but it is seldom that anything specific is done along this line and when proper ventilation is added the difference in cost of installation over warm- 96 Ventilation. ing with air becomes still greater. The perfect heating of a house with warm air is only made possible by first pro viding adequate ventilation because, before the warm air can enter a room the cold air must first escape. With both hot water and steam the house is most easily and cheaply warmed when there is the least ventilation. We shall consider first the warm air method of heating and ventilation because, for homes of moderate cost, and especially in the country, distant from plumbing facilities, this method is more readily managed as well as more cheaply installed; and because such a dwelling must then be thoroughly ventilated if it is warmed. The first require- ment is a warm, close construction and, everything consid- ered, the cheapest thoroughly warm construction is a frame house sheated inside and out with low-grade hemlock, hav- ing the outer layer of sheating covered with the cheapest grade of roofing tin or a very light weight of galvanized iron carefully and closely nailed with edges slightly over- lapping to thoroughly exclude the air. Walls so built may then be treated outside and in with any desired finish to suit the taste. The two thicknesses of %-inch dry lumber forming air spaces between the studding, even if the boards are not matched or tongued and grooved, so long as the metal is used to thoroughly stop air circulation, will give a far warmer wall than building papers for the reason that the soft wood is, both because of its texture and its greater thickness, superior as an insulator to the building papers. All spaces between studding should be thoroughly closed at the level of the three floors, which may be readily and best done by fitting in between the studding rough boards and then filling in with about six inches of a lean mortar, or concrete, which will thoroughly close the spaces and make the walls vermin-proof. Storm sash, fitting closely, on all but plate glass windows, should be provided. Farm houses should all have a cellar and floored attic the full size of the house. Both spaces are needed for both service and warmth and the extra cost, considering what is gained, should not lead to their omission. A good furnace of am Heating with Warm Air and Ventilation. 97 In at ceiling From/\ furnace f loor Fig. 40. — Method of introducing warmed air from furnace at the ceiling and of removing the fouled, exhausted and cooled air from the floor, both through the same space in the partition. 98 Ventilation. ' [ill ^ pie size, with conveniences for storing fuel, should occupy the basement, the location being chosen with special refer- ence to the most direct connection between the furnace and the rooms to be heated. Both the warmed, fresh air and Attic the fouled, depleted and cooled air may be most advantageously con- veyed through the partitions in the manner represented in Fig. 40, the warm air, as represented by the long arrow, passing from the furnace through the flue and entering the room at the level of the ceiling while a corresponding volume is forced out from the floor level as shown by the other two arrows. "Seconal floor ^^ most houses constructed in the =^=- manner described it will only be nec- essary for the ventilating flues to ex- tend into the attic ventilating all rooms into this space which then makes an excellent clothes drying room for blustering and stormy weather. The air may pass either directly into the attic from each room, or it may be passed into the room above, thus warming it indi- rectly in the manner represented in Fig. 41. In this case the warmed air flue extends to the level of the ceiling of the' room on the second floor where it is closed, the air leav- ing by an opening at the ceiling of the first floor. With this arrange- Fig. 41.— Method of ventii- ment forccd ventilation for the first into an upper one. floor is provided. The flue' being all the time filled with warm air heats the surrounding air in the same space thus giving a column 18 or 20 feet long to aid in producing a draft out of the lower room. The ^^ Warned f—* Oft I « Coo/ed Firss-section of Ventilating Flues. 119 On the left side of the figure is illustrated another way of providing intakes. The space between a pair of stud- ding is closed at the proper hight and all but the upper portion is divided hy sl partition in the manner shown. This partition is most simply formed out of a piece of light galvanized iron of proper width and hight having the bot- tom and the two sides turned at a right angle for the pur- pose of nailing it in place. Where the siding of the barn is nailed in place vertically intakes may be formed by using two strips of galvanized iron formed up as just described, nailing them on opposite sides, each with the open end down, thus forming two arms, one outside and the other in- side extending through the stable ceiling with the two con- necting at the top through an opening cut in the siding. Where masonry walls are being constructed for stables the intakes are readily formed in the building of them by placing in the wall a proper form. The forms may be hol- low building tile, drain tile or shapes in wood providing the desired capacity, simply set in the place desired and the wall built about them. From the statements made relating to the principles of ventilation, in the preceding section, it follows that the area of cross-section of both the outtakes and the intakes must de- pend in an important degree upon the hight of the out- take. If the ventilating shaft is low then it must have a sufficiently larger cross-section to compensate for the less velocity of air current in the flue which is always associated with short shafts. In my earlier writing it was stated that a ventilating flue 2x2 feet through which the air moved at the rate of 295 feet per minute, or a little more than 3 miles per hour, gave sufficient air for 20 dairy cows. This state- ment does not mean that any flue 2x2 feet will carry out of the stable sufficient air for 20 cows. Such a flue can do so only when the velocity of the air current is rather more than 3 miles per hour. Let us refer back to the table on page 56. Take the column for the 20 foot outtake. These cubic feet of flow per hour for the one-foot flue also mean velocity in feet per- 120 Ventilation. hour, and hence if we divide these numbers by 60 the result will be the velocity in feet per* minute. Doing this we get the round numbers 97, 307, 434, 532, and 615 feet respect- ively for stables which are warm enough so that the air in the flue is 1°, 10°, 20°, 30°, and 40° warmer than the air outside. But these are theoretical velocities, no allowance having been made for friction and other resistance to flow. It is quite likely that the actual velocities might not be more than one-half those computed. If so then only the last three differences in temperature between the air in the outtake and that out doors, namely 20°, 30°, and 40° will permit a 20-foot flue to supply air enough for 20 cows when its size is 2x2 feet. As the cows must breathe all of the time and as there are times when there is little or no effective wind, dif- ference in temperature must chiefly determine the dimen- sions of the outtake and intakes and the two should be ap- proximately equal in area of cross-section. The difference between the stable temperature and that of the outside air as given on page 66 ranges from 24° to 61° and averages 39°. The temperature in the ventilating flue will certainly average materially below that in the stable and as it is the temperature in the ventilating flue, compared with that out- side, which determines the draft, the mean effective differ- ence of temperature will be found to average materially less than 39° and probably nearer 20° than 30°. With a tem- perature difference of 25° a 30-foot shaft will give just about the required flow. The conclusion which should gov- ern practice, therefore, is : Outtakes and intakes for horses and cows should provide not less than 30 square inches per head when the outtake has a hight of 30 feet; if the outtake is shorter the area should he greater, if higher it may he less. A 20-foot outtake would require about 36 square inches per head instead of 30. Ventilation for Swine and Sheep. In the construction of quarters for both swine and sheep it has been the practice to build lower ceilings and quite Ventilation of Piggery. 121 generally lower stables for them than for horses and cattle. Both kinds of animals being small and given the freedom of the stable in common, over-crowding has been more frequent and this practice, coupled with the lower ceilings, has re- sulted in their suffering from the effects of insufficient ven- tilation oftener than horses and than cattle, except in later years when the number of individuals in a herd has been greatly increased. Sheep are extremely well protected from cold by their heavy fleece of wool ; so too, are swine of cold climates, when in good condition, by the thick layer of fat interposed between the skin and the more vital parts, serv- ing the double purpose of nourishment stored against need and a weather garment. We doubt very much, however, that these protections mean these animals are, necessarily, best maintained in severe climates with little or no shelter. In- deed, in the admitted absence of exact knowledge to the con- trary, there are good reasons for the belief that if both sheep and swine could be wintered under temperature conditions varying but little from 35° F., except when they are given freedom for needed exercise, better results would follow than with simple protection from winter storms, provided ample ventilation always went with the warmer housing. The thorough insulation nature has provided for the bodies of these animals makes it necessary that a larger percent of the heat produced in the body must be wasted through breathing and, for this reason, it may be expected that they will thrive better in a somewhat colder air than will cattle, but only enough colder to remove the animal heat through the relatively smaller surface. For the reasons stated, if sheep and swine are housed, relatively larger air movement should be continuously maintained through the stable, and for the additional one that they breathe more air per hour in proportion to their weight. Then because the stables are lower, the outtakes shorter, and the difference in temperature less and the wind velocities as well, it is necessary to provide relatively larger outtakes and intakes. If the minimum movement of air through a 1-foot outtake 20 feet high is taken at one-half the 122 Ventilation. value in the table, page 56, where the temperature difference between the air in the flue and that outside is 10°, it will be 9,204 cubic feet per hour ; with this rate of flow and on the basis of 1,392 cu. ft. and 917 cu. ft. of fresh air per hour and per head for swine and sheep respectively there should be provided an area of 22 sq. in. per head for swine and 15 sq. in. for sheep for both outtake and intake flues. If the outtake flue has a hight of only 15 feet then the number of square inches should be not less than 26 for swine and 17 square inches for sheep per head for outtake and intake flues. For 16 swine provided for, as represented in the floor plan, htahe i North side t IntaKe Feed alley Bedroom Feed floor D Bedroom \ feed floor D I OuffaKe \ Feed floor Bedroom [ Feed floor Bedroom D '' Ir}tahe w ^InlaKe w ■ Intake w Hntake Fig. 61.— Showing floor-plan and ventilation of a piggery. The outtake extends to within 12 inches of the floor and admits air on four sides. Fig. 61, the outtake would need to be not less than 18x18 inches inside with a hight of 20 feet ; and 20x20 inches if the hight is 15 feet. With the outtake located centrally and consisting of a single flue it has the maximum efficiency and a minimum cost. In the next illustration. Fig. 62, is represented both floor plan and elevation of a sheep stable with a ventilation sys- tem installed which is both incomplete and inadequate. Ob- serve that the outtakes all terminate below the level of the ridge of the roof, which both lessens their efficiency and ren- ders them liable to reverse draft when the wind is in one - direction. In the 80 feet covered by the 10 pens there are Ventilation of Sheep Stables. 123 provided as many outtakes, each ^x^^ inches and less than 15 feet high. The space ventilated should accommodate at least 50 sheep ; each of the 10 outtakes should then have had a cross-section of 85 instead of 36 sq. in. as they do possess. A single central outtake 28x28 inches, rising directly i_ ~— i Fig. 62. — Showing floor-plan and elevation of sheep stable in which the outtakes are too short, too small and more numerous than needed; and where no intakes have been provided, as should have been. through the ridge of the roof 20 feet above the stable floor, would give much more efficient ventilation. Two main flues 18x21 inches placed one-third the distance from either end would be rather better than a single central flue. Intakes discharging air in at the ceiling and drawing it from near the ground level outside should be distributed along each side with openings 3x12 inches, 20 of them, 10 on a side. Yentilation of Poultry Houses. So soon as an attempt is made to house any considerable number of hens in warm winter quarters, not made so with 124 Ventilation. the aid of artificial heat, provision for ventilation becomes imperative if healthful conditions are desired. It has been stated that a hen breathes about 1 . 2 cubic feet of air per hour. In one hour 50 hens would respire 60 cubic feet, highly charge it with moisture and raise its temperature to near 97 ^ This is 2.68 per cent of the volume of air con- tained in a room 20x16x7 feet, the space commonly allotted to this number of birds. There is heat enough in 60 cubic feet of air at 97° to represent 97X60=5,820 cu. ft. raised 1°. The total air in the room in question is 2,240 cu. ft. Sup- pose this has a temperature of 20° ; this is heat enough to represent, taking out the 60 cu. ft. the hens have breathed, 2,180X20=43,600 cu. ft. raised 1°. If we now add these products we have 43,600+5,820=49,420 cu. ft. raised 1°. Dividing this total by the total amount of air in the room we get 49,420-^^2,240=22°. That is to say the 50 hens, by breathing 60 cubic feet of air out of the 2,240 and warming it to 97°, letting it again mix with the balance in the room, have raised the general temperature from 20° to 22°. It is clear, from these fig- ures that 50 hens are unable to warm through many degrees any large volume of air. Prof. Gowell, of the Maine Agricultural Experiment Sta- tion, recognizing this fact in a practical way, has designed for poultry houses a sleeping chamber, by enclosing the roosts in a floored space just under the ceiling and provid- ing the entire front side of this chamber with doors of rather light canvass, hinged at the ceiling so that on cold nights these may be closed down for warmth. The size of the sleeping chamber recommended by Gowell is less than 4x4x20 feet and the only ventilation provided is through the ■canvass doors. It is clear that the smaller volume of air enclosed in the sleeping chamber would be maintained at a higher temperature unless the air was changed in it at a Ventilation of Poultry Houses. 125 more rapid rate. Taking the capacity of the chamber at 320 cubic feet and supposing that its air is changed once per hour and replaced with that at 20°, breathing alone, not al- lowing for loss, should maintain a temperature 14° higher or 34°, the air of the chamber having one-seventh the vol- ume of the room considered above. But if the air in the chamber is changed but once per hour it would contain 18.75 per cent of air once breathed, instead' of 3.3 per cent, the standard we have assumed as possibly permissible for Cellar to warm Poultry house Fig. 63. — Showing method of ventilating a poultry house. A is sleeping chamber without floor; B is flue to admit warmed air to sleeping chamber from cellar if one is provided; C is duct to admit air from floor of house to cellar to be warmed. If no warming cellar is pro- vided the floor should be cemented. COWS. We doubt if under the conditions recommended by Gowell the air Avill be changed oftener than once or twice per hour and such a rate does not appear to be sufficient. In view of the considerations here presented we have de- signed the poultry house represented in Fig. 63. As shown, it is 16x20x7 feet and intended for 50 hens. To guard against low temperature a cellar is suggested under the whole floor with provision for air to circulate as shown in the drawing, thus utilizing the ground heat for warming. If a location can be chosen which permits all but the south 126 Ventilation. front to be largely in the bank and a cement floor is pro- vided to conduct the heat of the subsoil into the house through the general floor, this will do much for warmth. Indeed, with four long windows on the south, we do not hesitate to recommend, for severe climates, placing the chicken house in a bank with the floor cemented and 18 to 24 inches below the ground level in front. Such a house, because it can be more thoroughly ventilated, will be less damp and more wholesome. For houses wholly above ground, the walls must be closely and warmly constructed. A very warm wall may be made with 2x8 's set 3 feet apart, covered with drop sid- ing outside and matched fencing inside or, what would be best, a light weight of galvanized iron nailed closely and vertically to the studding, filling the spaces between the studding compactly with dry fibrous peat. The ceiling likewise should be similarly built so that no air may escape through it. A very warm ceiling could be made by tightly packing the space above very closely with marsh hay, rep- resented in Fig. 63. A very warm poultry house can be made by using 2x8 studding, covered with drop sid- ing outside and only with a light weight of galvanized iron inside, with the space between the studding closely packed with fine marsh hay and treating the ceiling as already described. The closely packed hay makes one of the best of nonconductors, while the metal makes the walls and ceiling both air-tight and sanitary in every way. It will be clear from statements made on page 63 that where the ventilating flue for poultry houses may rise 16 feet above the floor the cross-section of both outtakes and intakes should provide some 4 square inches per bird, or at the rate of 200 square inches for each 50 hens or their equivalent. INDEX. Abbot, Dr. C. G., letter, 84: relative intensity of sky lig-ht, 84; best window exposure, 85: form of window for max- imum liffhting-, 85: comparative amount of lig-ht from sky and sun. 85. Air. amount breathed b.v different an- imals. 9: amount inadeauate without definite provision, 19: amount used in combustion. 8: composition, of pure, 13, — of once breathed. 14. 68.— of stable, 70: continuous flow necessar.v. 17: cost of warming, 66: density, of pure at dif- ferent temperatures,68, — of respired at different temperatures. 68, — difference of, demonstrated. 69: experimental de- monstration of chang-es in respired, 13, 15, 16. 69: formulas for computing- flow of, 47, 48, 55: graphic representa- tion of amount breathed, 10; once breathed loses in food value. 11: rate of flow in outtakes, 56, 57, 59, 60, 66,— due to wind pressure. 47, 57.— due to wind suction. 48, 57,— due to difference in temperature. 53. 55, 56, — due to hu- midity, 61; specific heat of, 66: volume of. required for dwelling-s, 36, 41, 90,— for stables, 41,42.43. 62,— for cows and horses, 42, 43, 120,— for sheep and swine. 43, 121,— for poultry, 41, 42, 63, 126,— breathed per hour, 10. Armsby, Dr. H. P.. amount of moisture transpired by steer, 34. Blood, aeration of, 6: corpuscles, 6.— ex- tent of surface, 7,— function of, 6: movement of, 7, ■Carbon dioxide, amount in air, 13. 14, — in stable air. 37, 40, 70: as index of air purity, 36: how removed from system, 6. Carnelly, standard of air purity, 36. Clarke, composition of air, 13. Cow. air breathed per hour, 9. 10: cross- section of ventilating- flue for, 42, 120: heat produced by, 64: moisture trans- pired by, 34: ventilation experiment with. 28, 37, 38, 70: ventilation of stables for, 109-120. Colin, amount of air respired b.v differ- ent animals, 9. De Chaumont. standard of air purity for man, 36: volume of air movement for man, 36. Diseases, susceptibility to contagious, 24, 89. I Dwelling-s, ventilation of, 88, — by fire- places. 88, 95— by stoves, 91, — when warmed with hot air, 93,— when warm- ed witli steam or hot water. 73. 100. Fireplace, ventilation by. 88. 95. Florham Park stables, 53, 59. 60. Flues, flow of air in, theoretical, 56, 57. — methods of computmg-. 52. 55.— ob- served. .59. 60. 66: for houses. 92. 97. 98. 101: for school-houses. 103. 106; for stables. 107. 109. 111-118. 123. 126: hig-ht, 60: size, 60, 63. 120, 121, 126; capacity of. 56. 57, 63, 122. Gowell, G. M., ventilation of poultry houses. 124. Haldane, standard of air purity, 36. Heat, amount g-iven off by cow. 64: mo- tive power in ventilation. 52. 56. 67: utilized in ventilation. 71: specific. 66. Heating-, poultry houses with sub-cel- lar. 125: rural school-houses. 103, 106; with fireplaces, 88. 95: witli hot-air furnaces, 96: with steam and hot water, 100; with stoves. 91, 106. Hen, air breathed per hour. 9. — required in ventilation. 41. 42.— warmed by breathing-. 124: moisture thrown off by, 28; outtakes and intakes for, 126. Horse, air breathed per hour. 9, 10.— vol- ume of, for g-ood ventilation, 41, 42; area of outtakes and intalces for. 120, House, warming- and ventilation, 88-102; type of, readily warmed and ven- tilated, 102: ventilated, with fire- place. 88-95,— with hot-air furnaces, 96.— when heated with steam or hot water, 100.— witli stoves. 91. Humidity, as motive power in ventila- tion. 60-63: of air in U. S., 34; of re- spired air, 14, 32. Intakes, 49, 72. 74. 75: for dairy stables, 59. 72. 75. 111-114. 117. 118: for base- ment stables. 118: for dwelling-s, 92,101: for pig-g-eries. 122: for poultry houses, 125; for schoolhouses. 103, 105, 106: size, 120. 122. 123. 126: types of, 109; velocity of flow throug-h, 59. Jordan, Dr, W. H., composition of stable air. 37, 73; heat g-iven off by cow, 64. Jordan. E. L., air movement throug-h stable. 65; temperature of stable, 65. Lamp, oil burned by, 20. 90; ventilation experiments with, 20-23, 27. 128 Index. Light. Abbot, views and observations on, 84; amount admitted by windows, 85, 86. 87; cannot be depended upon for complete destruction of germs, 83; destroyer of disease germs, 81; for dwellings and stables, 78; from whole sky compared with sun. 85; most in- tense from south sky, 85; Weinzirl. on destruction of disease germs by, 82. Magnesium ribbon, combustion in pure and breathed air, 12. 13. Man, air breathed per hour, 9. 10,— re- ■ Quired in ventilation, 41, 42,— standard of purity for, 36; amount of moisture transpired by. 33. Moisture, amount transpired by man, 32,— by cow, 33,— amount of air re- quired to remove, 33. 34: as motive power in ventilation, 60; effect on air density, 68; in respired air, 14. Nitrogen, amount in air, 13, 14. Offices, ventilating. 73, 75. Outtake, cross-section for. 120. 121, 126; defective shelter for. 50. 51. 52: dimen- sions, for cows and horses, 62. 120, — for swine and sheep. 63, 121. — for poultry, 63, 126; for horses, 92, 97. 100; for school-houses. 102. 106: for stables. 74, 107, 109. 111-117.122. 123. 125; hight of , 53, 56, 63, 126; location of, 74; essential characteristics of. 107: proper termi- nation for. 53; table of rate of flow through, 56. 57. 59, 60. 'o^. Oxygen, amount consumed by man. at different temperatures. 77 : amount in air. 13. 14; effects of deficiency of , 24: required in combustion, 1, 8. Pigs, airbreathedperhour, 9, 10, — move- ment for ventilation, 41, 43; venti- lation for. 63. 121, 123. Poultry, ventilation for, 63. 125. Pressure, due to difference in temper- ature. 52. 55: due to humidity. 60: due to wind impact. 47; due to wind suc- tion, 48. School-house, warming and ventilation of, 73. 103, 106. Seguin. moisture transpired by man. 33. Shaw, W. N., velocity of air in flues due to different wind velocities, measured by, 58. Sheep, air breathed per hour. 9, 10.— re- quired for ventilation, 41, 43: ventila- tion for. 121, 124. Shelters for outtakes, 50 — 53. Stables, air movement to prevent mois- ture condensation, 33, 34; composition, of air in. 37. 39. 70; lighting for. 79: ■ maximum lighting effect for. 86; per- meability of walls to ail". 37. 38: ven- tilation of, 107; windows for, 80, 81,. 86, 87. Stoves, as ventilators, 91, 106. Temperature, best for room and stable-- 76; computed maintenance for sta- bles. 65: observed in stables. 66, 70;: difference of, in ventilation, 56. 58. Tobin tubes, 75. Twombly, H. McK., stables of, 53, 59. Ventilation, and maintenance of tem- perature 64: demonstration chamber for, 20: experiments, with cows. 28. 38, 66, 70,— with hens, 22, 23.— with lamp, 20, 23: extra heat needed for not great, 67; flues, improper installation of,. 50.— shelter for, 51-53; for sheep and swine, 120: for poultry. 123: full utili- zation of waste heat in .securing. 67; maintenance of temperature to in- crease, 71 ; mean effective difference in temperature for. in houses. 58, — in stables. 58; motive power in, wind im- pact. 47. — wind suction. 48.— differ- ence in temperature, 52, 55. — humidity of air, 60; mean effective wind veloc- ity for, 58; mean effective difference in temperature for, in houses. 58. — in stables, 58: need of increasing, 18. 88: of body tissues. 3: of dairy stables, 109: of houses already built, 90; of new and remodeled houses, 94; of school-houses, 102; of stables. 107: power required in, 46; practice of, 76: principles of. 45; principles of construction for. 73; problem of. stated, 41: serious effect* follow insufficient, 24; through flre- place. 88: through stoves, 91, 106. Weinzirl. Dr. John, efficiency of light as a germicide. 82. Wind, action in producing ventilation, 49: flow, due to impact of, 47. 57. — due to suctional effect of. 48, 57: mean ef- fective velocity of. 58.— may be very small or nil. 62; pi'essure of, 47; suc- tional effect of. 48. Windows, efficiency of. 86-88: faulty arrangement of . 80: forni and expos- ure of for maximm lighting. 81; num- ber, size and exposure, 79: south ex- posure best. THE SOIL By F. H. KING Professor of Agricultural Physics in the University of Wisconsin. 1888-1901 ; Chief of the Division of Soil Management, U. S. Department of Agricul- ture, 1901-1904. Author of "Irrigation and Drainage," 1899; "Physics of Agricultiire," 1901 ; "Tillage, Its Philosophy and Practice," "The Necessity and Practice of Drainage", in Cyclopedia of American Agriculture, 1907 ; "Drainage ^ and "Irrigation," in The Standard Cyclopedia of Modem Agriculture, (British) 1908. 303 pages, 7x5 inches, 45 illustrations.— $1.68 prepaid. CONTENTS Introduction ^~ 2" The Nature, Functions, Origin and Wasting of Soils 27-69 Texture, Composition and Kinds of Soils 70-106 Nitrogen of the Soil 107-134 Capillarity, Solution, Diffusion and Osmosis 135-153 Soil Water 154-183 Conservation of Soil Moisture 184-206 The Distribution of Roots in the Soil 207-217 Soil Temperature 218-238 The Relation of Air to Soil 239-252 Farm Drainage 253-267 Irrigation 268-275 Physical Effects of Tillage and Fertilizers 276-294 "I consider it a most desirable addition to our agricultural literature, and a distinct advance over previous treatises on the same subject, not only for popular use, but also for students and specialists." * * * ' Dr. E. W. Hilgard, Director Calif. State Agr. Exp. Station. "For practicability and entertaining power combined this work is at the head of its class." — The Boston Traveller. "The manual is brief, accurate, comprehensive and hits the practical point every time." — Independent. "It is a book which progressive farmers will come to' regard as one of the essential implements of farm life." — Boston Daily Advertiser. "The great point about the book, in our opinion, is its thorough practical nature. Personally the writer is acquainted with probably all modem works on this vitally important question * * * ; but we certainly never derived so real benefit from the perusal of any two, nay, even three or four works of this character, as from the one now under consideration." — E. Kemp Toogood, F. R. H. S. in Royal Cornwall Gazette. IRRIGATION AND DRAINAGE By F. H. KING Professor of Agricultural Physics in the University of Wisconsin, 1888-1901 : Chief of the Division of Soil Management, U. S. Department of Agriculture 1901-1904. ' Author of "The Soil," 1895 ; "Physics of Agriculture," 1901 ; "Tillage, Its Philosophy and Practice", "The Necessity, and Practice of Drainage", in Cyclopedia of American Agriculture, 1907 ; "Drainage" and "Irrigation In The Standard Cyclopedia of Modern Agriculture, (British), 1908. 502 pages, 7x5 inches, 163 illustrations. — $1.66 prepaid. CONTENTS Introduction 1_ qq PART I. IRRIGATION CULTURE The Extent and Geographic Range of Irrigation 66- 90 The Conditions which make Irrigation Imperative, Desirable, or Neces- sary 91-116 The Extent to which Tillage may take the Place of Irrigation 117-170 The Increase of Yield Due to Irrigation in Humid Climates 171-195 Amount and Measurement of Water for Irrigation 196-221 Frequency, Amount and Measurement of Water for Single Irrigations.. 222-247 Characier of Water for Irrigation 248-268 Alkali Lands 269-289 Supplying Water for Irrigation '. . 290-328 Methods of Applying Water in Irrigation 329-402 Sewage Irrigation 403-414 PART II. FARM DRAINAGE Principles of Drainage .' 415-466 Practical Details of Underdrainage 467-492 "To the ordinary farmer the title of this book is somewhat misleading. If he is not In an irrigating district, and has no wet lands, he will at once con- clude, on seeing the title, that the subjects treated in the book do not concern him to the extent of $1.50. If, however, by chance he has the opportunity of reading the book he will change his opinion. The proper amount of water available at the right time is essential to successful or profitable farming In any country, and, therefore, Professor King opens his books with some general re- marks on the importance of water ; on the texture of the soil necessary to con- serve the moisture ; and follows it up with the report of some experiments show- big the amount of water used by plants, which will be a surprise to the farmers who have not investigated the subject. The method by which the water is ob- tained by plants and exhaled ; the remarkable way in which the plants them- selves control the demand, economize water, so to speak ; the mechanism by which the roots get hold of the moisture ; the extent of the root surface ; all these are treated in a wonderfully interesting way in this book, and are of all- absorbing interest to the man who is farming for dear life, and, if he Is properly awake to the Importance of the subject, will prove as interesting as a novel We regard it as one of the most valuable contributions made to the science of agriculture in recent years." — Wallaces' Farmer. "But althouffh the author travels far and wide in search of examples and re- sults in Illustration of the principles which he advances, and so far Introduces matter which Is of great importance in the discussion of, irrigation proper, yet the bulk of what he has written is full of instruction of the most practical character for the rent-paying farmer." — Manchester (England) Guardian. orr> 1