-NRLF B REESE LIBRARY UNIVERSITY OF CALIFOR; Accession No. pOy . ChssNo. MANUALS OF HEALTH. NOTES ON THE VENTILATION AND WARMING OF HOUSES, CHURCHES, SCHOOLS, AND OTHER BUILDINGS. BY THE LATE ERNEST H. JACOB, M.A., M.D. (OxoN.), PROFESSOR OF PATHOLOGY, YORKSHIRE COLLEGE, LEEDS. PUBLISHED UNDER THE DIRECTION OF THE GENERAL LITERATURE COMMITTEE. LONDON : SOCIETY FOR PROMOTING CHRISTIAN KNOWLEDGE, NORTHUMBERLAND AVENUE, W.C. ; 43, QUEEN VICTORIA STREET, B.C. BRIGHTON : 135, NORTH STREET. NEW YORK : E. & J. B. YOUNG & CO. 1894. [While this little book was going through the press its gifted author was called away from the world. His life, full of promise, was brought to an end on March 1st, 1894.] INTRODUCTION. THE present work is an attempt to put into popular form information respecting matters of health which are very little understood by the general public. These subjects are considered in technical works on engineering, and in bulky treatises on Hygiene, written for the use of Medical Officers of Health and Sani- tary Engineers ; but these books are not generally accessible to the ordinary reader. Certain excellent chapters on the subject of ventilation may be found in somg- recent Manuals on the subject of Health, but mixed with much extraneous matter, such as directions for diet and exercise. The present notes are the result of considerable practical experience in examining and dealing with insanitary buildings, and the remedies recommended have all been practically tried and proved successful. It is hoped that the book will be found useful by the general householder no less than by those who are interested in the sanitation of schools, churches, and similar buildings. iv Introduction. The author wishes to express his thanks to Prof. Goodman, of the Yorkshire College, for assistance in the revision of the engineering formulae in the chapters on calculation methods, and to his various friends of the architectural profession, and others who have allowed him to use their drawings to illustrate the work. Acknowledgments are also due to the Clarendon Press ; Messrs. Crosby Lockwood, & Co. ; Messrs. Churchill ; Kegan Paul & Co. ; and Mr. Jackson, for the loan of engravings, or permission to use illustrations of which they possess the copyright. E. H. J. Leeds, January 1894. CONTENTS. CHAP. PAGE y i. THE NECESSITY OF VENTILATION 9 ii. THE PRESENT INSANITARY STATE OF BUILDINGS 25 in. CONDITIONS NECESSARY FOR GOOD VENTILATION 28 IV. METHODS OF WARMING 34 v. METHODS OF LIGHTING 49 1 THE MOVEMENT OF THE AIR AND LAWS OF AIR VII. J 1 CURRENTS ... ... ... ... 55 , 58 VIII. THE VENTILATION OF HOUSES 70 IX. ,, ,, CHURCHES 78 X. ,, ,, SCHOOLS 81 XI. ,, ,, ,, HOSPITALS 88 XII. ,, ,, ,, CONCERT-ROOMS, ETC. 93 XIII. ,, ,, ,, WORKSHOPS 95 XIV. SUCCESSFUL VENTILATION SCHEMES 97 XV. EXAMPLES OF METHODS BY WHICH BAD VENTIL- ATION MAY BE IMPROVED 100 XVI. METHODS OF CALCULATION, FORMULA, ETC. 113 XVII. BIBLIOGRAPHY 121 APPENDIX 123 ILLUSTRATIONS. FIG. PAGE 1. DESAGULIERS* BLOWING ENGINE 10 2. GAUGER'S HOT-AIR GRATE 37 3. TEALE FIREPLACE COMPANY'S VENTILATING GRATE 38 3. CURRENTS OF AIR IN ROOM 39 4. NASON RADIATOR 45 5. COIL CASE, WITH MIXING VALVE 46 6. ,, ,, ,, 47 7. GAS GOVERNOR BURNER 51 8. BLACKMAN FAN 58 9. CURRENTS OF AIR FROM TUBE 62 10. CURRENTS OF AIR IN BENT TUBE 63 11. CIRCULATION OF AIR IN ROOM LIGHTED BY GAS ... 75 12. SCHEME OF VENTILATION FOR CHURCH 80 13. VENTILATION OF LEEDS BOYS* MODERN SCHOOL ... 84 14. ,, ,, YORKSHIRE COLLEGE, LEEDS ... 85 15. ,, ,, SCHOOL (U.S.) 87 16. CURRENTS OF AIR IN HOSPITAL WARD ... ... 89 - 7 - OF THE UNIVERSITY NOTES ON THE VENTILATION OF BUILDINGS, CHAPTER I THE NECESSITY OF VENTILATION. HENTILATION is a term applied to the method by which a due supply of fresh air is main- tained in buildings and other confined places, such as nrines and ships. The word was invented about two hundred years ago by Dr. Desaguliers, a well-known scientific man of the time, who devoted a great deal of time, money, and inventive skill towards improving the sanitary condition of buildings, as well as of ships, the con- dition of which, even at that time, was considered very bad. In the course of his work Dr. Desaguliers in- vented a "fanning wheel" (Fig. 1), or what we now call a "fan" or "air propeller," which was worked by manual power, and the man who worked the fan was called the " ventilator." The word has since been divorced from its original meaning, and used to denote a hole in a building through which air may (or may not) pass, according to circumstances. Every one knows that a supply of air is necessary \ for all living things, a few of the lowest vegetable organisms excepted. To cover the head with a cloth for a short time produces a sense of oppression, and 10 Notes on the Ventilation of Buildings. the removal of the veil is followed by a feeling of relief. This sense of oppression is increased by the heat which is given off from the breath, and there is Fig. 1. Desaguliers' "Blowing Engine," and Hales' Ventilating Bellows (1734). Tomlinson. considerable confusion in the minds of most people as to the relative effects of the fouling and the mere heat- i ing of the air by respiration. People commonly say of a crowded building " it is too hot," whereas most of the The Necessity of Ventilation. 11 discomfort comes from the impurity of the atmosphere. I There is no sense of oppression felt in a well- ventilated I Turkish bath, although the temperature may be very* high. Air, or rather oxygen, which is the effective agent in the mixture of gases we call atmospheric air, is abso- lutely necessary for life. The maintenance of ouri bodily heat, energy, and the complex processes neces-i sary for " life," depends on a constant^supply of oxygen. / The other substances we require, viz. carbon, hydro- gen, nitrogen, &c., which we take in the form of food, can be supplied at varying intervals. Oxygen we/ must have continually. Life, to represent the complex by the simple, may be regarded chemically as similar to the burning of a lamp, a lamp which has the power of making its own oil and renewing its own wick, when supplied with necessary materials for the manu- facture. In the lamp flame the oxygen of the air combines with and converts the carbon and hydrogen of the oil into carbonic acid and water. We write the process chemically thus n*i 5 Carbon _ Carbonic acid ~ Hydrogen- -^^Water (H,0). A- __ 4 Oxygen r ~~ | Nitrogen (takes no part in the process). In a lamp this operation goes on with such rapidity as to cause heat enough to make the disengaged par- ticles of carbon incandescent, and so we get light. In the human body the process is slower, and the temper- ature remains at about 98 Fahr., but the essence of the process is the same, and the products are also mainly carbonic acid and water. A glance at the analysis of the air before and after it has passed through the lungs will show how great is the change produced by respiration, and how very I foul the expired air becomes. Pure air consists of a mixture of about 21 parts of oxygen, 79 of nitrogen r lVEBSITY 12 Notes on the Ventilation of Buildings. in 100, some watery vapour, a trace of ammonia, 1 and carbonic acid 4 parts in 10,000. Expired air con- tains not only about 5 per cent, less oxygen, but car- bonic acid in the enormous proportion of 470 parts in 10,000, and is moreover heated to the temperature of the body, about 98, and is saturated with moisture. In addition to these changes, expired air contains an organic impurity of perceptible odour, which we recognize as a " stuffy smell," and there are exhal- ations more or less odorous from the skin. There is considerable difference of opinion among physiologists as to the precise impurity which pro- duces the deleterious effect which is felt in crowded rooms. Some experiments made in Paris a few years ago, seemed to show conclusively that the principal agent was the organic impurity referred to above. Recently, however, these experiments have been re- peated, both in Germany and England, with negative results ; and it seems probable that, as was originally held, the excess of carbonic acid must be credited with the injurious effects noted. This is upheld by the fact that the effects produced in a room crowded with people are very similar to those perceived when much gas is burnt in an un ventilated room. No doubt, however, the unpleasant sensations are inten- sified by the effect on the delicate sense of smell of the disagreeable exhalations referred to above. However this may be, an estimation of the carbonic acid present in a given sample of air is, speaking generally, a fair test of its purity. The fumes of burnt gas have just been referred to, and in fact this source of impurity is an extremely important one. Besides carbonic acid and water, which are produced by the combustion of coal-gas, sulphurous acid is given off, and if the gas flame be cooled to any extent, as occurs in cooking-stoves, a very pungent gas called acetylene is formed. In addition, recent investigations seem to show the presence, in minute quantities, of carbon monoxide, The Necessity of Ventilation. 13 which is one of the most poisonous gases known, and, as an ingredient of coal-gas, is the active agent in the many deaths which have been caused by the accidental escape of gas in houses. Air may be tested for carbonic acid roughly by the following method. Six stoppered bottles are taken, containing respect- ively 450, 350, 300, 250, 200, and 100 cubic centimetres. These are filled with the air of the room which has to be tested by means of a small hand-ball syringe. A glass tube or pipette, holding exactly 15 cubic centimetres, is then filled with clear transparent lime- water and emptied into the smallest bottle, which is then shaken. If the fluid becomes turbid, the amount of carbonic acid will be at least 16 parts in 10,000. If no turbidity appears, repeat the operation with the next largest bottle. Turbidity will here indicate 12 parts. In similar fashion, turbidity in the 250 c.c. bottle indicates 10 parts CO 2 ; in the 300 c.c. bottle 8 parts ; in the 350 c.c. bottle 7 parts, and in the 450 c c. bottle less than 6 parts. To judge of the turbidity, mark a piece of paper with a lead-pencil, and gum it on to the bottle with the mark inside. If there be turbidity the mark will be invisible. The method usually adopted by chemists is to take a large jar, holding about a gallon the large " spice jars" used by confectioners answer very well. This is filled with the air to be examined by means of bel- lows. 100 c.c. of lime-water are put in, and the bottle shaken and allowed to stand. The alkalinity of the lime-water is then ascertained by measuring the amount of oxalic acid which is required to neutralize it before and after it has been shaken up with the air. The oxalic acid solution is made by dissolving 5'64 grms. of crystallized oxalic acid in a litre of water, and is of such strength that 1 c.c. will exactly cor- respond with 1 c.c. of carbon dioxide. An example will show the manner of working. 14 Notes on the Ventilation of Buildings. 50 c.c. of the lime-water required 34 c.c. oxalic acid solution for neutralization. ,, ^ (after shaking with air) required 32 c.c. ,, ,, Difference 2 = c.c. of C0 2 in the lime-water used. As the 30 c.c. was only half that used in the test, the number must be doubled, i. e. 4 c.c. The capacity of the bottle was 4100 c.c. . *. 4000 c.c. (i. e. 4100-100 c.c. taken up by the lime- water) (4 litres) of air contain 4 c.c. of carbon dioxide = 1 per cent., or 10 parts in 10,000. Solution of phenol phthalein is generally used to indicate the point of neutralization. For further accuracy it is advisable to make a cor- rection for temperature, the standard weight being given at zero Centigrade. For this, '002 per cent, should be added for every degree above 32 Fahr. Corrections for pressure are less necessary. For fur- ther details the reader is referred to special works on chemical analysis. The following figures give an average view of the insanitary state of most of our public buildings. The figures are given in parts per 10,000, 4 being the standard for the open air, and 6 the best obtainable ventilation for a building. Analyses made in Leeds by Professor Thorpe. C0 2 . Sitting-room near floor ... . ... 7*33 ,, half-way up ... . ... 9" near ceiling ... . ... 14'65 Grand Theatre, Leeds pit ... . ... 15'01 ,, ,, upper circle . ... 14 '29 balcony ... . ... 1416 Philosophical Hall after lecture ... . ... 13 '38 Analyses in Nottingham by Professor Clowes. Grounds of University College ... ... ... 4'3 Chemical Laboratory of University College ... 6*9 TJie Necessity of Ventilation. 15 C0 2 . Masonic Hall during a dance ... ... ... 31* Circus ... ... ... ... ... 32'6 Committee-room with 15 persons and 27 gas-jets ... ' 41'8 Dr. Angus Smith gives the following from Manchester. Theatre Royal pit ... ... ... ... 27 '34 gallery ... 13'58 School-room ... ... ... ... ... 9*7 Mills (400 people) (1) 28'6 (2) 29-6 (3) 30- London. Chancery Court ... ... ... ... 19'3 Olympic Theatre ... ... ... ... 10' Standard Theatre ... ... ... ... 32' We may remark, with reference to the above figures, on the very excellent ventilation of the Chemical Theatre at the Nottingham University College, con- sidering that at the time it was filled with students, each using a Bunsen burner. The fact that the upper gallery of a theatre may be purer than the pit may be explained that the pit, generally very crowded, is often largely covered over, and the ceiling low, while, the fumes being attracted to the central chandelier, the air from the lower parts penetrates the upper galleries to a very slight extent. The effects of breathing respired air have been tested by various observers, the person making them being placed in a closed chamber, or inspiring and expiring into an india-rubber bag. The susceptibility of various individuals varies greatly. The following is a brief account of the researches of Dr. Angus Smith, who had a special leaden chamber constructed for the purpose. Considering that conditions very nearly similar to those produced by Dr. Angus Smith are daily present in hundreds of assembly-rooms, churches, and other buildings, it is well that we should note his results. Speaking of bad air and its effects, Dr. Smith says 16 Notes on the Ventilation of Buildings* " Here I am describing feelings, and to some persons they may simply be fancies, but I shall describe them nevertheless, as I believe man has learnt nearly all he knows of ventilation by attention to these feelings, while chemical analysis is attempting to struggle after him, and is continually finding itself behind him in the race. " The first trial of the chamber was made by simply sitting down 1 hr. 40 min. This produced about 1 per cent, of CO 2 (carbonic acid gas). No difference was to a certainty perceptible for 25 minutes. Then when the air was drawn from the top by means of an umbrella, it seemed like a soft wind, and had to some extent a pleasant feeling, but was entirely devoid of a faculty of cheering. "After an hour the unpleasant smell of organic matter, such as is so well known in a crowded school, was perceptible on movement. It was decidedly perceived, after remaining an hour, that the air was very soft when made to move. This arose from the moisture, and shows us at once that a v soft air may be a very impure one. Soft air with a good deal of vapour is very soothing ; it calms the mind and the body, and the burning of a candle and a fire. After staying in the chamber for 100 minutes, the air had an unpleasant flavour or smell, and I came out. Three persons entered at once, and pronounced it very bad. It seemed to me, however, that we are frequently exposed to air equally bad, though I have never found any in daily life so much deprived of its oxygen (20 per cent). I was very glad of the escape from this impure air, the gladness not arising from any previous discomfort. There was unusual delight in the mere act of breathing, which feeling continued for four hours. " The second stay in the chamber was continued for 160 minutes. After 140 minutes it was observed that very long inspirations became frequent, and more agreeable than usual. The air about that time had a I UNIVERSITY 1 The Necessity of Ventilation, l^r 17 very decided feeling of closeness. Immediately on opening the door two or three persons entered, and again perceived how uncomfortable it was." Experiments were then made on the combustion 'of candles, and it was found that in one instance four miners' candles went out after five hours' burning, and again that eight candles, one paraffin lamp, and one spirit-lamp were all out in 150 minutes. The room was then entered, the persons carry ing candles and a spirit- lamp. The lights were soon extinguished, and it was found impossible to kindle them with matches. Never- theless, they could breathe, though every one was glad to go out. No very correct description of their feelings could be given. Dr. Smith adds : "All these experiments tend to diminish our faith in our feelings as guides under certain conditions. The senses are quite unable to measure degrees of closeness." The importance of this observation can hardly be over-estimated. "A young lady was anxious to be in the chamber when the candles went out. She was very fond of pure air, but was not much struck with the impurity of the air in the chamber, though the candles were threatening to go out, so that there could not have been quite 19 per cent, of oxygen, with 2'1 per cent, of CO 2 . She stood for five minutes quite well, but suddenly became white, and could not come out without help." It is impossible to read the accounts of these experi- ments without being reminded of what we may at any time feel and see in a crowded church at an evening service, or many theatres, though the latter are, as a rule, better ventilated than churches. Not many years ago a colossal suffocation experiment was made in a large town in the north of England. This, though less disastrous than the well-known catastrophe of the "Black Hole of Calcutta," was on a much larger scale, arid quite sufficiently unpleasant to those who took part in it. A great politician was expected, to make an impor- B 18 Notes on the Ventilation of Buildings. tant speech. As there was no room of sufficient dimensions available in the town, a large courtyard, surrounded with buildings, was temporarily roofed over, some space being left under the eaves for ventilation. Long before the appointed time several thousand people assembled, and in due course the meeting began ; but before the speaker had got well into his subject, there arose from the vast multitude a cry for air, numbers of people were fainting, and every one felt oppressed and well-nigh stifled. It was only after some active persons had climbed on the roof and forcibly torn off the boards for a space about twenty feet square, that the business of the meeting could be resumed. This occurrence so exactly illustrates the ignorance prevailing on the subject of ventilation, that it deserves wider publicity than it obtained at the time. We would point out that the question of the provision of fresh air was not forgotten, the fault lay in the builder's ignorance of the laws governing move- ments of air. And yet this method of so-called venti- lation is in use (and useless) in numbers of buildings at the present day. The general effects of exposure to air contaminated by the products of respiration or the burning of gas, may be summed up as the following Headache, sometimes felt at the time, and of long duration, but occasionally not coining on till some hours afterwards, perhaps the next morning. It then takes the "migraine" or sick headache type, with its accompanying symptoms of vertigo, intolerance of light and sound, and occasionally vomiting. Besides headache, there is generally sleepiness, lassitude, inability to fix the attention, and loss of appetite. It is not uncommon to hear clergymen complain of feeling^ " Mondayish," as they term it. On Monday morning they are accustomed to suffer from exhaustion, headache, and a feeling of malaise. This is attributed to the hard work of Sunday, but the real reason is to be found in the intolerable atmosphere breathed on The Necessity of Ventilation. ]tf Sunday night in a crowded church, and there are many cases to show that an improvement in the atmosphere of the church entirely removes the weekly headache, with no curtailment of work. The symptoms and sensations described above are frequently experienced by those who only occasionally are exposed to foul air, as in theatres, churches, &c. The effects on the health of those who habitually live and work in crowded and un ventilated buildings are un- happily only too well known. Sir John Simon wrote in 1863, in one of two series of masterly essays on public health which characterized his administration as the sanitary adviser of the Privy Council : " In proportion as the people of a district are attracted to any collective indoor occupation, in such proportions (ceteris paribus) the district death-rate from lung disease will in- crease." In that year (1863) the deaths from con- sumption in the country districts being taken as 100, the deaths in Manchester counted 263, and in Leeds 218. The greatest mortality took place among printers and tailors, classes who work largely by night, re- quiring a strong light, which necessitates the burning of much gas. On the other hand, contemporary statistics showed that the miners of Northumberland and Durham, where the pits were freely ventilated, formed an important exception to this rule. The necessity of keeping mines free from explosive gas has forced the managers to employ powerful ventilation apparatus, and a recent writer (Reports of the Labora- tory of College of Physicians, Edinburgh, 1891), after a careful investigation of the health of a large mining district in Scotland, finds that with the improved atmospheric conditions the miners' liability to pul- monary consumption has disappeared. Workshops are still far from perfect, though vastly improved by the more general use of ventilating fans. The white faces of the working girls in too many of our great towns still tell a sad story, although an army of government inspectors are commissioned to report on any insani- 20 Notes on the Ventilation of Buildings. tary conditions. But "quis custodiet custodes?" The inspectors are conscientious, well-educated gentlemen, but not skilled in sanitary knowledge. Next, as to the amount of air required. A person standing in the open air, on a calm day, is exposed to about 32,000 cubic feet of air passing by him per hour. It is out of the question that he should be supplied with this amount in a closed space, but careful experiments on barrack-rooms by the late Dr. Parkes, Professor of Hygiene at the Military Medical School at Netley, have shown that the best room ventilation which can be reasonably available will supply 3000 feet per head per hour. The air will then remain absolutely without sensible odour, and the carbonic acid impurity will not exceed 6 parts in 10,000. This is ideal ventilation for rooms inhabited the whole day, as hospitals, &c., and this amount is generally provided in good hospitals for cases of infectious diseases. In the case of rooms inhabited for shorter periods, churches, assembly-rooms, and the like, a much smaller amount of air will suffice, but the smallest amount which could be called even moderately good ventilation would be not less than 500 cubic feet per head per hour. This means that an ordinary sitting-room 16 x 16 x 12 ft., containing about 3000 cubic feet, would require for continuous use the air to be changed once an hour for one person, three times an hour for three persons, but if used for merely an hour or two at a time, it would be fairly wholesome with eight persons, if the air be changed three times an hour, and there be no gas burnt. It would be, however, a difficult matter in so small a room to effect this without causing draughts. In rooms occupied for a short time only the amount of air required per head varies according to the size of the room. The following table from Parkes shows the amount required during the first hour under these circumstances, the full amount of 3000 cubic feet being required for the second hour. 3000 The Necessity of Ventilation. ' 2 Amount of air required to dilute to standard of 6 parts of C0'2 in 10,000. Cubic space Air required for Subsequent per head. 1st hour. hour's. 100 2900 "| 200 2800 300 2700 400 2600 500 2500 600 2400 700 2300 800 2200 900 2100 1000 2000 The following table represents the generally-accepted standard of good ventilation. Cubic feet per head per hour. Hospitals (general) 3000 ,, (infectious) 5000 Theatres 2000 Assembly-rooms ... ... 2000 Prisons 1760 "Workshops (ordinary) 2000 ,, (unhealthy) ... 3500 Barracks (day) 2000 (night) 2000 Schools (adult) 2000 (infant) 1000 Stables 6000 When the proportion of carbonic acid in a room, as the result of respiration, is increased from the usual propor- tion of 4 in 10,000 to about 8, a faint musty odour can generally be detected by any one entering the room from the outside air. As a rule, it may be said that if the atmosphere of a room is quite free from unpleasant odour to a person entering from a fresh atmosphere outside, there is very little fault to be found with the ventilation of the room as far as the effective change of air is concerned. This musty smell, however, is 22 Notes on the Ventilation of Buildings. frequently masked by stronger odours, flowers, per- fumes, &c., and then an air analysis must be referred to. The amount of air required for comfort depends largely on the temperature of the external air, as well as the dimensions of the room. With regard to the latter, it is generally allowed that very lofty rooms are not desirable ; they are difficult to warm, and there is a kind of reservoir of cold air at the top. Ordinary living-rooms should not be more than 14 feet high, and a little lower is preferable. With regard to the differ- ence of temperature, Dr. Billings remarks : "It will be found that when the outside air is below the freezing- point, and the room has the usual proportion of external wall and window space, the amount of air- supply per hour shall be about Ij times the cubic contents of the room, otherwise either the room will not be kept warm, or the fresh air will have to be introduced at a much higher temperature than is desirable for health or comfort." This is more appli- cable to the conditions found in the Northern States of America, where not only is the winter temperature very low, but the average temperature preferred in a living-room is about 10 higher than that considered sufficient in England. American houses are generally kept at about 70. Dr. Billings further remarks : " The higher the external temperature, the more air is re- quired for comfort. There are some days in summer when sufficient air to secure comfort can hardly be obtained even in the open air, and the feeling of having insufficient air is often felt in a crowd, though in the open air." The amount of crowding allowable in a room is a rather important question. Practically, as there is very little efficient ventilation in most buildings, it is the practice to allow a comparatively large area per individual. If, however, there is a regulated supply of air, a point is reached at which the due supply of air would be required to move at too great a velocity for comfort, say more than five feet per second, so that we The Necessity of Ventilation. 23 must really restrict the crowding even of well- ventilated - rooms to that point at which sufficient air can be given at a velocity not exceeding five feet per second. One occasionally sees a court of law so crowded that an adequate supply of air would render it difficult for the counsel to retain their wigs. Some explanation must be given of the reason why so large an amount of air is required, considering the small amount we actually inspire. We may illustrate by the analogy of a water-supply. Engineers allow a minimum of twenty gallons a head in estimating the amount of water to be supplied to a town. The water is taken from a tap into a basin, and having been used, is discharged into a drain. The fouled water does not mix with the common supply. Now imagine a household of ten persons, with the twenty gallons per head in one central cistern, from which all water is to be taken and to which it must be returned. Something of this kind obtains in many village com- munities in India, but in civilized countries would be considered an inexpressibly foul arrangement. If there were no sinks or waste pipes, nothing short of a rapid stream of many thousand gallons a head through the house would meet the difficulty. A precisely similar condition of things exists with reference to our air- supply in a confined space. The air we breathe is taken from a common stock, and breathed back with all its gaseous impurities, laden with moisture and heat, into the common stock, which rapidly becomes foul, unless constantly removed. The prodigious amount of air we require is not for the purpose of supplying us with oxygen, but in order so to dilute the poisonous substances produced by respiration, that they become innocuous and free from odour. We have mentioned some of the evils incidental to an insufficient supply of air. It seems hardly necessary to state the converse of this as an incentive to the obtaining of proper sanitary conditions. A few may be given as instances. 24 frotes on the Ventilation of Buildings. In the early days of sanitation, the operatives in a mill in which a fan had been erected for ventilating purposes applied to the proprietors for increased wages^ on the plea that they ate so much more food ! But they also did much more work. The same remark as to work has been frequently observed by school-masters. An experienced master lately observed to the writer : " In the old school " (where the rooms were close and imventilated) " the boys used to get tired about four o'clock, but here, in our new buildings, they work on well to the end." In this school a carefully-designed system of ventilation changed the air in the rooms three times an hour. In Healthy places of worship there are no sleepers among the congregation, and the minister wakes on Monday morning none the worse for his Sunday's work. With the ventilation of mines and workshops, the mortality from consumption has steadily decreased. By the ventilation of the stables of the French cavalry the mortality among the horses was reduced from 197 per 1000 to 20. "A horse seldom takes cold ' from exposure to cold, but frequently is made ill from being too warm," says Major Fisher (Through the Stable and Saddle-room). " It is the inside, not the outside air that gives them coughs, sore throats, congestion of the lungs, and sundry other ills to which horseflesh is heir." The same applies to cows, and all animals which are kept in confinement, as the directors of the Zoological Gardens have found to their cost. Some interesting observations have been made by Carnelly and Haldane in a recent examination of school buildings in Dundee ventilated by mechanical means and otherwise. Thev found that on examining the air of the school-rooms for micro-organisms, a very much smaller proportion were found in the schools mechanically ventilated. More than ^this, when the ventilation in these schools was intermitted for a time, it was found that on resuming the working of the fan, the air still remained comparatively free from micro- 'flie Present Insanitary State of Buildings. 25 organisms. The reasonable explanation of this is, that the ventilated rooms contained little which could act as a nidus or appropriate soil for these organisms to inhabit. ( Vide Appendix.) The micro-organisms here referred to are not neces- sarily germs of disease. Many are perfectly harmless. Many produce what we call putrefaction when growing in organic matter, and may be described as Nature's scavengers. Still, where the conditions for breeding micro-organisms exist, those producing disease may be found with the rest, and there is no doubt that pure air is comparatively free from these forms of life. As a matter of fact, the air of a well-ventilated sewer contains fewer micro-organisms than many a school- room or workshop. CHAPTER II. THE PRESENT INSANITARY STATE OP BUILDINGS. WE have seen that the living body breathes, that is, takes in oxygen and expels carbonic acid, some fifteen to twenty times a minute during its whole life. It is obvious that buildings which are to hold living bodies must breathe also, although the precise mechanism by which the change of air is effected may be different. When we come to examine by this standard existing buildings, we find things by no means satisfactory. Builders know that wooden floors must be ventilated, or the "dry rot" fungus, the Merulius lacrymans, will feed on their substance and destroy them ; but the idea that breathing human beings in a confined space require any special arrangements for supplying them with air at a convenient temperature has seldom taken a practical form churches, houses, schools are being built every day in which the subject is entirely neg- lected. Concert-rooms and theatres are slightly better, 26 Notes on the Ventilation of Buildings. inasmuch as it is usual to use " Sunlights," or other ventilating gas-burners for lighting purposes ; but the buildings are seldom fitted with any properly-devised machinery for the purpose. Exception may be made in the case of certain recently-erected theatres, in which mechanical power is used, and school-boards are beginning to adopt similar measures to render healthy schools in large towns, but in most cases architects are content to introduce an occasional air-brick, or a patent contrivance called a ''ventilator," which is speedily stopped up, and people stifle in silence, apparently possessed with the idea that it is impossible to intro- duce fresh air into an inhabited room without its being felt as a draught. The worst offenders against the laws of health are those responsible for the building of churches and other places of worship. The reason of this is not far to seek . A church is built on a conventional plan, fixed in mediaeval times, when churches were less crowded, services shorter, and above all, at a time when there was no lighting by gas. As every point about the structure of a church has been settled by a fixed authority, it is very difficult to introduce changes, and the plans for a new church pass the authorities all the more easily if they are of the conventional type. The usual form of church building, copying as it does more or less closely the beautiful architecture of the thir- teenth or fourteenth centuries, is by no means an ideal form from a sanitary point of view, whatever it may be from other considerations. It is generally built in the form of a nave and side aisles, lighted by clerestory windows. This gives, including the chancel, four ceil- ings of three different heights, making it most difficult to extract the air at the level of the roof. The clere- story windows chill the warm air as it rises, and send it down in the form of a cold douche on the heads of the congregation. The roof is lofty and dark, necessi- tating a large amount of light, and as a rule about twice as much gas is burned for lighting purposes as is The Present Insanitary State of Buildings. 27 necessary. The pillars obstruct the view of the preacher and the altar from at least ten per cent, of the congregation. The building is too frequently used but once a week, and is therefore hurriedly warmed -at the end of the week, an operation often very imperfectly performed ; and last but not least a degree of economy is generally exercised both in the erection and manage- ment which is fatal to the obtaining of perfect sanitary conditions. Bad as churches .generally are found to be when examined from a sanitary point of view, Nonconformist chapels are generally worse, on account of the frequency of galleries and the consequent crowding. Worst of all are probably the numerous mission-rooms which, through the energy of the clergy, are found in so large numbers in the poorer districts of our large towns. These are frequently extemporized out of a couple of cottages. No architect 'is consulted on the subject, the alterations are made by some local builder, and sanitary conditions are absolutely unthought of. The strictest economy is observed, especially in the heating apparatus, which is generally a small stove, and every Sunday a large class of more or less unwashed children is succeeded by a , crowd of totally unwashed adults, till the atmosphere of the rooms can only be described as sickening. It is proposed in the following pages to lay down the general principles by which buildings are rendered healthy, with some practical hints on the treatment of such rooms as the above, on which, owing to their tem- porary nature, it is not desirable to expend much money. Iron churches are as bad as mission-rooms, and have besides the disadvantage of being intolerably hot in summer. Sunday-schools vary, but are usually very bad, except when they consist of small class- rooms heated by an open fire. 28 Notes on the Ventilation of Buildings, CHAPTER III. CONDITIONS NECESSARY FOR GOOD VENTILATION. WHAT now do we mean by speaking of a room as " ventilated " 1 Real ventilation is so uncommon that there is no general popular consensus on the subject. The architect usually thinks this object has been attained if some of the windows can be opened. Some think that the presence of " ventilators, especially if they have long names, and are secured by "Her Majesty's letters patent," ensures the required end. We may as well attempt to supply a house with water by making a trap-door in the roor to admit the rain. The answer given by sanitarians to the question of " What is a ventilated room, suitable for human beings to inhabit in comfort and health 1 " is very definite as regards general principles. Three conditions must be fulfilled 1. The building must have its walls warmed to the temperature at which it is required the air should be kept, otherwise a person near the wall will feel cold. 2. A supply of air, in quantity depending on the number of people (speaking generally for rooms not,, continuously occupied, about 1000 feet per head per hour), must be caused to pass uniformly through the room, at a velocity not exceeding five feet per second. 3. This air must have its temperature so modified by heating or cooling apparatus that, while it gives rise to neither cold nor hot draughts, the temperature of the room remains constant. Other refinements may be added, such as arrangements for filtering and moistening the air, which will greatly add to the comfort of the occupants. Although this is easily stated, the problem of carry- ing out these points, especially the third, in rooms of varying size, under circumstances of varying degrees of crowding and great differences of temperature, is by no means easy. Conditions Necessary for Good Ventilation. 29 It is very necessary to observe the great importance in this scheme of the heating apparatus. In the climate of England the cooling of the air will be a luxury only occasionally required, and reserved for theatres and places of public resort, where expense is not so care- fully considered. Warming, however, is necessary during more than half the year, during nearly three- quarters of the year in the northern parts of the British Isles ; and the fact that heating apparatus is not, as a rule, designed to assist ventilation, either as regards its size or its position, is the principal reason why so few buildings are either healthy or comfortable. The general public, led by advertisements, invests largely in ventilators ; these are found to cause draughts and are immediately closed, the fact being that it is impossible to introduce sufficient fresh air into a crowded room in cold weather, unless the air be heated. When any attempt is made toirnprove the air-supply to any completed building, it will be invariably found that the principal difficulty lies in connection with the heating arrangements. As a matter of fact it is im- possible to carry out a perfect system of ventilation for a house or other building, unless the heating and ventilation arrangements are designed by the same person ; in fact, the heating must be completely sub- ordinate to the ventilation. Unless this is so it is impossible to obtain good results, and the reason why the ventilation of most buildings is a failure, consists entirely of the fact of t*he heating apparatus not hav- ing been designed for this purpose. The amount of radiating surface is calculated on a basis which may fulfil the first condition referred to above, i. e. the warming of the walls of the room, but cannot possibly fulfil the last and most important, i. e. the warming of the incoming air. A glance at the ordinary method of procedure' will show how very unlikely it is that satisfactory sanitary results can be obtained. 30 Notes on the Ventilation of Buildings. An architect is instructed to prepare plans for a church, school, or similar building. These are pre- sented to the building committee, and are criticized entirely from the point of view of the architectural appearance and the general convenience of the arrange- ments. Occasionally some too active member of the committee ventures to 'ask the architect if he has made any arrangements for ventilation. He always receives the reply, " that the subject has received the most care- ful attention, and that when the building is finished it will be found perfect in that respect." The inquisi- tive member of the committee subsides, suppressed. The plans are then, in the case of an ecclesiastical building, submitted to the Bishop, and through him to the diocesan architect. The latter considers carefully the structural arrangements, in order that the building may be well built and durable ; he may make inquiry as to the probable nature and situation of the heating apparatus, with a view to considering any risk from fire which may be possible, but the sanitary condition of the building, as a receptacle for a number of living, breathing, air-consuming human creatures, is entirely neglected. The plans are now passed, and the build- ing is commenced. In the course of its erection the architect selects certain makers of heating apparatus to tender for the warming of the building, and the relative merits of hot air and hot water are discussed. If economy is a principal object, a cheap hot-air appa- ratus is ordered, and this is the most unwholesome machine which can possibly be put in a church. If wiser counsels prevail, hot-water pipes are fixed ; but as these are generally placed beneath the floor in channels, where they become speedily covered by a coating of non-conducting dust, a much larger amount of piping is required than if they were placed above- ground, and there is generally an unpleasant smell from the burnt dust. Finally the church is finished and consecrated, and mutual congratulations are ex- changed. Unhappily, it soon becomes apparent that, Conditions Necessary for Good Ventilation. 31 except in the summer, when the windows can be kept open, the building is, especially at an evening service, much too hot and very " stuffy." There is an offensive smell from the gas, in spite of the fact that it is lowered during the sermon, to allow the audience to slumber more peacefully under the influence of the increasing quantity of carbonic acid. Eventually, the congrega- tion is divided between those who prefer rheumatism and bronchitis with open windows, and those who prefer asphyxia with the windows shut. The next stage is the calling in of some maker of patent ventilators, who disfigures the church inside and out with metal tubes and other unsightly con- trivances. But although in mild weather these make a slight improvement, on the first cold day such a cataract of draught is felt, that the new ventilators are soon all closed, and once closed they remain so. The congregation mournfully resign themselves to the conviction that ventilation is an impossible thing. Under the circumstances it must be feared they are not far wrong. This is no fancy sketch. Cases of this kind may be found in plenty. Although something can be done to improve a build- ing in which these mistakes have been made, as will be seen on reference to the examples given further on, it is impossible to render such a church or other building sanitarily satisfactory without a complete reconstruction of the heating, and probably of the lighting arrangements. The contractor for the warm- ing apparatus undertook only to maintain the building at a certain temperature in the absence of ventilation, and he carries out his contract strictly. He has nothing to do with ventilation unless he receives due instruc- tions on that point and a " ventilating engineer " can do nothing without the heating engineer. As an illustration of the great difference between mere heating arid what is necessary for ventilation purposes, the case of a large school recently built may OF THE UNIVERSITY 32 Notes on the Ventilation of Buildings. be quoted. A ventilation scheme was carefully devised by a special committee of the managers who were familiar with the subject, and a tender obtained from an experienced heating engineer. This gentleman said, as he handed in his contract, " If you wish me to heat the building in the usual style, I will do so for rather less than half the sum named in the tender." Good ventilation cannot be carried out without the expenditure of money, and is unfortunately rather costly, the principal item of expense being the in- creased amount of heat required. The cheapest way of_heating a room is to fill it with people, close every opening, and let them "stew in their own juice," and this is what is frequently done, with the effect on health mentioned in the first chapter. It is found that when people are crowded together in a large town, it is necessary to have elaborate engineering arrangements to supply them with water, and communities cheerfully and confidently expend millions in bringing pure water from distant reservoirs, the cost being distributed by means of a rate. It is equally true that when people are crowded together in a room, they require a supply of pure air artificially supplied to them, and the cost of this should be as cheerfully paid as that of water or gas. We have attempted in the precediig pages to point out why the method generally adopted in the erection of a church or school fails to give satisfactory results. Let us give, on the other side, a sketch of a different method, drawn from recent experience. The building to be erected was a large school, to be used for various technical purposes, containing labora- tories, lecture-rooms, museums, &c. As soon as the plans and elevations had been approved of, a small com- mittee was appointed to consider with the architect the general principles of the ventilation and heating. They decided on steam as the means of heating, and a fan, actuated by a gas engine, as the means of venti- lation. The architect was now commissioned to consult Conditions Necessary for Good Ventilation. 33 an engineer of special experience in this subject, and by him, in consultation with the architect, a complete scheme was drawn up, the position of every flue was determined, the amount of heating surface for every room calculated on the basis of the amount of venti- lation necessary for that room, and every detail arranged before the building was commenced. More- over, during the erection of the building a represent- ative of the engineer consulted was frequently present to ensure that the projected constructive arrangements were properly carried out. The architect here wisely shared his responsibility witli the sanitary expert. This is the method which gives the best, and indeed the only good results. Through the rapid increase of knowledge on sanitary subjects, the architectural pro- fession has burdens laid on it heavier than it can bear, and it is only by the co-operation of architectural and sanitary experts that we can hope to erect buildings on a level, not only with the artistic taste, but also with the sanitary knowledge of the day. Though we boast of our advance on other nations in sanitary matters, the ventilation of public buildings is much more carefully considered on the Continent than in England. Mr. Bacon (Robin's Technical School and College Building) remarks that in this respect the Belgian architects do not neglect the matter even if their clients do so, and it is not long since M. Bacckel- mans of Antwerp actually refused to carry out the erection of the town hospital a building of consider- able importance because the Hospital Commission would not appoint an engineer to consider the plans with him, with regard to the heating and ventilation, before the foundations were laid. Is it too much to ask that in the case of ecclesiastical buildings, in the matter of which there is so much skilled supervision of plans, that the Bishop should number among his advisers a sanitary as well as an architectural expert, and that no plans for a church should be passed unless there were good reason to o 34 Notes on the Ventilation of Buildings. believe that the building when erected would be a healthy one in use ? On expressing this opinion recently to two members of the Episcopal Bench, the author received the reply that it would be impossible for the Bishop to reject the plans unless he was prepared to instruct the builders of the church by what method it was to be ventilated. The Bishop might as well refrain from recommending an oak door because lie was unfamiliar with the details of joiners' work, or a bell, because he did not know the precise composition of the alloy used. If there be a demand for professional knowledge on this point, there will be no lack of a supply. It is in the first erection that the necessary provision can be easily and economically made. It has been well said, "It is easy to make a building breathe if it is caught young." The provision of proper channels and openings is then a simple matter, and the increase of cost is mainly in consequence of the larger amount of heating surface necessary. CHAPTER IV, METHODS OF WARMING. CONSIDERING the important part taken by the heating apparatus in any scheme of ventilation, it will be well to discuss a little more fully the methods in use for warming buildings. Heat, as will be seen on reference to the general principles laid down in the first chapter, is required for two purposes : (1) For warming the walls of the building, and (2) for heating the incoming air. We must not' forget, however, the very large amount of heat which is contributed by the bodies of the living occupants of the building, an amount so as to render it necessary for the air which is supplied for ventilation purposes to be frequently cooler than Methods of Warming. 35 the air in the building by a few degrees, or the tem- perature inside rises unpleasantly if the building be crowded. Inasmuch as the same apparatus may be used for both purposes (viz. heating the building and the freshly-supplied air), the general question of venti- lating resolves itself into two factors, viz. the heating and the air propulsion. It is true that for a few months in the year heating is not required, but assem- bly-rooms, schools, and the like are used so much more frequently in the winter, for entertainments, &c., that heat will be required on the majority of occasions on which the building is in use. Heat, as usually available, is of two kinds, Radiant and Convected. Radiant heat is that which streams like light in straight lines from heated objects. You can hide the light of a candle from your face by a screen. In the same way you can screen the radiant heat of a fire. Like light also, radiant heat decreases with the square of the distance, so that a source of radiant heat, like a fire, is of very little use in warming a large space. We have here to use convected heat, which is commu- nicated from the lower parts of a room to the upper by means of the air. In a small room with a fire the fioor and walls are warmed by the radiant heat, and they in turn warm by convection the air in the room. The pleasantness of a fire- warmed room consists in the fact that the walls and objects in the room are warm, while the air is comparatively cool, and the air, being warmed by surfaces not highly heated, does not become dry. When hot- water pipes are used for heating pur- poses, the amount of radiant heat is very small, but the air surrounding the pipes becomes warm, the colder and heavier air around then forces it upwards, till by the circulation of currents of air the whole space becomes warm. There is more radiation from steam pipes, and more still from a highly-heated stove, but the higher the temperature of the heating surfaces the more dry does the air become, while the organic matter contained in the air becomes charred, and gives out 36 Notes on tJie Ventilation of Buildings. a disagreeable smell. It is the fashion to call hot- water and steam coils " radiators." This is a misnomer, as the amount of radiant heat they give out is small. They are really air heaters, but there is no other convenient term to apply to them. The usual methods of heating a building are 1. Open fires. 2. Stoves, or "hot-air apparatus." 3. Hot-water pipes : high and low pressure. 4. Steam pipes. Bearing in mind the double function of the heating apparatus, it is obvious that open fires are of very little use in connection with large rooms. They do not warm the air required for ventilation, although when fitted with a hot-air arrangement, as will be explained, they can be of some use in that matter. On the other hand, they are the best possible agents for heating a small room, where the air is not required to be changed more than once an hour. Much depends, however, on the kind of open fireplace in use. The open fire is a com- promise between heating and ventilation. It is possible to greatly increase the heating power by increasing the convecting surfaces and slowing the combustion and draught, as in the "Nautilus" grate and the "Front Hob" grate of the Teale Fireplace Co. On the other hand, by using none but radiant heat and quickening the draught, as in too many of our modern grates, in which the sides of the grate are of iron, the ashpit is open, and the chimney is at the back, we may reduce the heating effect to a minimum, and obtain only a large flow of air through the chimney. The kind of grate therefore which is adapted for a certain room must depend on the amount of ventilation required, remembering always that if a rapid com- bustion arrangement is used, there must be some auxiliary source of heat, whereby the entering air may be heated. The tendency in some quarters seems to be of late to reduce rapidity of consumption by check- ing the draught. This may be carried too far, and the age of draughts be succeeded by a period of stufiiness. When fitted with a chamber which communicates Methods of Warming, 37 with the external air, the open fireplace enlarges its sphere of usefulness considerably. The "hot-air," or "ventilating grate" as it is called, was invented by Gauger in France some two hundred years ago (Fig. 2). The best known form of it in England is the Fig. 2. The first Ventilating Grate by Gauger. model designed by Gal ton, but many good patterns are made by Boyd, Shorland, the Teale Fireplace Co. (Fig. 3), and others. Here air is taken from the outside, warmed by the waste heat in a chamber behind the grate, and poured warm into the room. The great increase of heating power obtained in this way, without in any way increasing the consumption of coal or reducing the value of the grate as a radiator, shows how waste- ful is the ordinary fireplace. The " ventilating grate " is used in all military hospitals and many other places, especially schools and small hospital wards, but is not nearly so much known as it deserves. Speaking generally, an open fireplace should have a form differing very little from that laid down by Eumford nearly a hundred years ago, and lately advocated anew by Mr. T. P. Teale of Leeds. The sides and back should be of firebrick, the back inclined forwards, so that the smoke leaves the fire in front rather than at the back. The rapidity of combustion is regulated by the size of the chimney, and the 38 Notes on the Ventilation of Buildings. supply^of air to the ashpit. With our present know- ledge it seems impossible to lay down fixed rules Fig. 3. Hot-air Grate, with concealed exit. Teale Fireplace Co. A, elevation showing perforated overmantel panel to admit warmed air. -Z?, section showing warming-chamber behind grate. as to what this rapidity should be. It must depend on the amount of ventilation required. Fig. 3a indi- Methods of Warming. 39 cates the direction of the air currents in a room heated by a fire, and shows that over the fireplace is a convenient position at which to introduce fresh air. Fig. 3. Sketch of Experiment made by Mr. Campbell iu 1857, showing the movement of currents of air in a room with an open fireplace. GALTON'S Health Dwellings. II. Stoves. This term includes every form of closed apparatus in which the air passes over surfaces directly heated by a fire, from the old-fashioned " cockle " to the latest form of American " furnace." They are extremely economical, if well constructed, and where economy is desired at the expense of comfort or health a stove will generally be adopted. A stove may be used to heat in four different ways 1. Standing in the building, surrounded freely by air. In this position it gives off a great deal of heat, by which the air in the room and eventually the walls are warmed. It is thus well adapted for heating a ware- house or storeroom, where no special ventilation is required. 40 Notes on the Ventilation of Buildings. 2. If the stove stand against an opening in an ex- ternal wall, or be furnished with a tube conducting air from the outside, its heat is expended partly on the air in the room, and partly on the incoming fresh air. In this way it acts partly as a simple heater, partly as a ventilator. 3. The stove may stand in a chamber communicating with the external air and with the building. This is the general way in which it is arranged for heating large buildings, and efficient ventilation may be obtained with this manner of heating, if the following conditions are strictly adhered to. (a) The stove must be very Jarge much larger than the makers' catalogues recommend, so as to allow of its giving adequate heat without the surfaces being over- heated. This will involve greater first cost, but great economy in working, as it will burn much less fuel and require very little attention. (b) A suitable exhaust must be arranged for the building, or otherwise a due amount of air will not be admitted. If the force which draws in the air be the excess of temperature in the apparatus chamber over that of the exterior air, no considerable amount will be introduced unless the temperature in the chamber be very high, and this means that the heated air will be dry, and tend to cause great discomfort. 4. Another way of fixing a furnace is to place it underground, but to arrange channels so that the air is drawn from one part of the building into the heating chamber and discharged, heated, into the building again. This practically comes to the same thing as when the stove is placed in the building itself. There is no possibility of ventilation, since to make an apparatus of this kind work well there should be no external openings, and it is in every respect a most unwholesome arrangement for churches and buildings occupied by people. Yet it is only too com- mon. Methods 3 and 4 are, however, by some heat- ing engineers combined, and there is no objection to Methods of Warming. 41 the latter plan being adopted merely for heating the building before it is occupied, if fresh air only be admitted to the heating chamber as soon as the building is sufficiently warmed. Still, taking them at their best, stoves, by whatever fancy name they may be -called, are very unsatisfactory things, for two reasons : (1st) . the surfaces are too highly heated for comfort, and the air is dried unpleasantly; (2nd) It is impossible to make a cast-iron furnace gas-tight. Experiments by Putnam (Open Fireplaces in all Ages) have shown that in the best form of American iron hot-air apparatus there is a constant outward pressure of one to eight milli- metres of water under ordinary circumstances, and that there is never an inward pressure, except when the draught up the smoke flue is too powerful to be left with safety. The same author gives a most amusing account of a furnace, guaranteed so confidently by its maker to be absolutely gas-tight, that he was allowed to test the matter by experiment. The simple pro- cedure of filling the apparatus with water showed the presence of innumerable apertures. "To the complete astonishment of the proprietor, and of the careful workmen standing around, the water which was poured in poured out again through nearly every one of the score of careful joints, until the furnace seemed to dis- solve and float away in its own tears" (Op. cit., p. 109). Practically, it is found that very few buildings heated by " hot air," i. e. a stove apparatus, are free at times from a most oppressive atmosphere, and were it possible to take a census of the number of persons who yearly faint in public buildings, it would be found that in nearly all of these the heating was by some form of hot air. The only place where these are indispensable is in a Turkish bath, where as a rule the ventilation is tolerably good, and a high temperature is required, very difficult to obtain by any other method. Mr. Putnam's experiments show that soapstone is imper- vious to gas at ordinary pressures, and it is much to be regretted that furnaces of that material which 42 Notes on the Ventilation of Buildings. are procurable in America should not be obtainable in England. The gas which escapes more or less from every cast-iron furnace, consists largely of the very poisonous carbon monoxide referred to above. III. Hot- water pipes heated by a boiler are the most generally available agents for heating churches and large buildings. Tlvere are great advantages in a good hot-water system. The heat is steady, it is impossible to over-heat the pipes, and the warmth is available exactly where it is wanted. It is under perfect control, and the circulation goes on till the pipes are cold. The method is readily adaptable to ventilation schemes. There are two methods in use, viz. the High and Low- Pressure systems. In the former, large pipes (three and four inches in diameter) are used, and the boiler is generally of the type of that used for steam. The temperature of the pipes seldom exceeds 150 Fahr. In the high-pressure system the pipes are very small, and calculated to resist a high pressure. The boiler is a coil of iron pipe placed in a furnace. The circulating water is very small in amount, and the heat is at its maximum very soon after the fire is lighted. The pipes become very hot, considerably above the tem- perature of boiling water. This renders a very small amount of piping sufficient, and the cost is accordingly much lower than that of a low-pressure system. Certain precautions are necessary to guard against fire, but if the apparatus is properly erected, and the furnace sufficiently large, it acts fairly satisfactorily. There is also a modification of this called the system of " limited high pressure," which has some advantages. All systems of hot-water heating are readily adaptable for ventilation purposes, as the pipes may be either collected in a large heating chamber, or distributed in a number of small ones, and are available for simple heating where no ventilation is required. IV. Until recently steam was very little used for warming houses or large institutions, its use being mostly confined to workshops, where the waste steam Methods of Warming. 43 from the engines was available. Methods, however, have been so improved by the practice of American engineers, that the system works with very little trouble, and there is now no reason why this plan should not be widely used for general heating purposes. It is especially convenient when power is required for some purpose connected with the building, as, for instance, to actuate a ventilating fan, to produce electric light, or work laundry machinery, for the same boiler then suffices as for the engine. Steam coils can be put in any position, and the temperature being high, they need not be large. They are easily shut off by a simple tap, but they are difficult to control, the coil, if it work silently, being either hot or cold. Methods for regulating the heat, however, are in use, and will be referred to later. The cost is slightly under that of a low-pressure hot-water system, but above that of a high-pressure arrangement. A steam boiler, however, requires rather more skilled stoking than a hot- water boiler, and careful inspection after it has been in use some years. Considering generally the various methods of heating large buildings, it may be said that if a steam boiler be required for any purpose, it will probably be the most economical and convenient to use steam also for heating purposes. Otherwise a low-pressure hot-water system, if erected with due care, leaves little to be desired. The arrangement, however, of the heating surfaces is of great importance. The methods of arrangement are usually classed as (1) direct, where the heating surface is placed in the rooms to be heated, and (2) indirect^ where the radiators are placed so that air passes over them into the rooms. It is obvious that the first method excludes the possibility of venti- lation according to the principles laid down above, while the second, or indirect method, lends itself to most methods of good ventilation. It is possible, however, in some cases to combine the two with advantage, as in most large establishments there are some rooms which 44 Notes on the Ventilation of Buildings. require very little ventilation, and here the placing of the heating surface inside the rooms has little to be set against it. This is termed the " Direct-indirect " method. Of late- there has been great improvement in the forms of radiators. Unsightly coils of pipe, which require hiding by ornamental gratings, are giving way to decorative forms of radiator, which can be daily cleansed. Cased coils are receptacles for dust, which becomes baked, and gives off an offensive smell. This is especially the case when pipes are put in channels under the floor, covered with gratings, an arrangement very common in churches. It is objectionable from many points of view. (1st) The pipes give off but comparatively little heat, and therefore an increased amount of piping is required. (2nd) They are soon covered with a layer of dust, which, besides giving off offensive odours, forms a non-conducting coating to the pipe, hindering the due discharge of heat. It is very important that the boiler should be of large size, so that the maximum heat may be obtained with moderate firing, at conveniently long intervals. The tendency is for the contractor to cut down the expense to the lowest point by tendering for the smallest size boiler which can keep the pipes hot. This means constant labour in firing, and great waste in fuel. The same applies to the estimation of heating surface. It is far better to have a large surface of low tempera- ture, if space can be given, rather than to have to keep the water at the highest temperature possible. The heating surface, as described above, should be placed in chambers through which the air passes on its way into the rooms. These chambers should be accessible for the purpose of cleaning, as well as of repair to the pipes. In America, " indirect" heaters are usually placed between the floors, horizontally, and are accessible from the ceiling of the room below. In England shallow coils placed in recesses in the wall of the room to be heated are more common, and the casing in front Methods of Warming. 45 open with hinges like an ordinary cupboard. In the case of a room requiring a good deal of heat and very little ventilation, e. g. a room with north aspect, occupied by only a small number of people, there is no objection to an open coil, furnished with an air-supply from behind or underneath. Many radiators are now made with this arrangement. It is most important that there should be complete control of the heat. This may be obtained in two ways. (1) By arrangement of the coils or radiators in Fig. 4. American Nason Kadiator, arranged in sections. three or more sections (vide Fig. 4), such a number being used as affords the necessary amount of heat. This is the best way when a large amount of heating surface is concentrated in a special chamber. (2) Where a coil fixed against an inlet in the wall is used for heating and ventilation, the apparatus shown in Figs. 5 and 6 will be found useful. The coil is enclosed 46 Notes on the Ventilation of Buildings. in a box furnished with a diaphragm running vertically throughout. By rotating the valve (D) at the upper part the stream of air is allowed to pass through the outer I Fig. 5. Author's Mixing- valve Box for wall radiators. channel unheated, or over the coil so as .to become warm, or by placing the valve in an intermediate position the air may be admitted of any required Methods of Warming. 47 temperature. By closing the inlet valve (B) at the base, the coil may be used entirely for heating purposes, the air circulating through the front opening (C), -Inlet Fig. 6. Author's Mixing-valve Coil-box for wall radiators. ventilation being set up the moment the valve is opened. This " mixing-valve " arrangement has been thoroughly tested, and is found to work well under 48 Notes on the Ventilation of Buildings. appropriate conditions ; the method is equally avail- able for hot- water and steam apparatus. Without a control arrangement of some kind, steam-heated buildings are generally, in this country, intolerably hot, except in the coldest weather. To sum up : when a room is filled with people, heat is only required for ventilation purposes (''indirect radiation"). When empty, "direct radiation," or an uncased radiator, is best. When partially filled, a radiator partly^open and partly ventilating ("direct indirect") is suitable. The estimation of the relative amount of "direct" and "indirect" heating surface is a matter requiring much judgment and experience. The following table, from the Records of the Smith- sonian Institute, shows the comparative advantages of the various systems described above. Form of Apparatus. Percentage of Thermal effect. Remarks. 1. Open fireplaces 2. Ventilating fireplaces 8. Metal stoves without air-supply 4. Stoves with air-supply 5. Hot- water pipes 6. Steam pipes 1012 3335 8790 6893 6575 5863 Carry off fresh air, and so bring in fresh but cold air, causing draughts. Carry off foul air and intro- duce warmed fresh air. Produce no change of air unhealthy. Admit as a rule insufficient air and too highly heated. Bad if cast iron, better if wrought iron. \ Easily adaptable for ven- j tilation purposes. Methods of Lighting, 49 CHAPTER V. METHODS OP LIGHTING. IT was stated in the first chapter that the air in inhabited rooms was greatly fouled by the burning of gas. Unless the lighting be by electricity by far the best method the manner by which a building is lighted is of great importance from a sanitary point of view. If a small number of good oil lamps be used, there will be very little in the way of excessive heat or objec- tionable smell, and it will only be necessary to allow fresh air to each lamp equal to that required for about three persons. Candles are so seldom used on a large scale that we may omit their consideration. On the other hand, lighting by gas, which is the most common method, involves considerable modification of the ventilation scheme. According to the way the burners are arranged, they may enormously increase the amount of fresh air required, and accordingly the cost ; or the lighting may be made to assist most usefully the necessary change of air. Considering the extensive use of gas for lighting purposes, and the frequent exhibitions of gas appara- tus held by municipal authorities, there are few subjects on which the public are more utterly ignorant. The ordinary gas-fitter knows nothing about the question of lighting. The knowledge of how to burn gas to the greatest advantage is in the hands of a few, mostly managers of gas-works and makers of gas-burners, who are riot as a rule consulted by the public. The compe- tition of the electric light lias recently greatly improved the methods of gas lighting, as well as drawn attention to the comparative cost of gas and electricity; but it is impossible to compare these without stating the par- ticular kind of gas lighting with which the comparison is made. 50 Notes on the Ventilation of Buildings. Lighting by gas may be done on three different scales of expenditure, with very different results. 1. The ordinary method employed in lighting domes- tic dwellings and churches is by a number of small burners of common type, e. bs Longitudinal/ Section. Fig. 12. General arrangement of heating apparatus and exit- flue for small church. municating with the church by a number of apertures. This should be led into the main exhaust shaft, and it will be convenient, if ventilating gas-burners are used, that the exit-pipes from the latter be led into the horizontal shaft. The consumption of gas should be carefully checked by the rules laid down in the chapter on gas-lighting. It is not generally known how much an organ is affected by difference of temperature. Ten degrees of tempera- The Ventilation of Schools. 81 ture above that at which the organ is tuned will serve to introduce the most horrible discord in a perfectly- tuned instrument. This may be often noticed at an evening service. In a properly-ventilated church the temperature should not rise. Revolutionary as these proposals may seem to one accustomed to the conventional (and insanitary) methods of church construction, they involve very little alteration in the usual structural arrangements, and if projected when the church is planned, do not neces- sarily entail a very large expense. The principal out- lay is on the increased amount of heating apparatus. Suggestions are given in a subsequent chapter as to the improvement of existing churches where ventilation is desired, with regard to other methods of heating. We would refer to the remarks made in Chapter IV. on the use of "hot-air " methods of heating. A stove may be used to heat the air, if there be an efficient exhaust. It is difficult, however, to properly control the heat of a stove, and the air becomes dried by the high temperature of the heating surfaces. Moreover, there is not the same facility in distributing the heat as obtains with a hot- water apparatus. It is not to be recommended on any score but that of economy. If the whole of the heating surfaces are in vaults below the church, there seems to be no objection to the use of stearn, except for the more constant tiring required. But if the radiators are in the church, it is difficult to make the system at all times silent. CHAPTER X. THE VENTILATION OF SCHOOLS. THE difficulty of ventilating schools increases directly with their size and complexity. A large collegiate build- ing, such as one of the University Colleges which have 82 Notes on the Ventilation of Buildings. arisen in our largest towns, consists of a number of rooms of various sizes, some being sitting- or common-rooms, others class-rooms, generally crowded, while there are besides chemical laboratories, in which special arrange- ments are required. School buildings of the more complex type present the most difficult problems to the ventilating engineer, and it is impossible in a work like the present to do more than point out some of the more important points which have to be considered. The principal failures in the ventilation of large buildings of this type have been through attempting to ventilate too large an area by means of one fan or other exhaust. This results in the rooms near the fan becoming efficiently ventilated, but the far ones re- ceive but little benefit. It will generally be found convenient to have a special fan or chimney exhaust for the chemical laboratories. It is no less important that the air-passages should receive careful attention, not only as to their design, but in the course of their construction. The allowance for friction, for length and angles, is generally under- estimated. In Mr. Robins' valuable work on technical school and college building, a careful survey is given of the venti- lation arrangements in a number of recently-erected colleges and technical schools of large size. There are three methods by which air may be supplied, viz. 1. Supply from one large heating chamber. 2. separate heating chambers. 3. cased coils in the rooms. For colleges, and similar buildings containing many rooms, in which various temperatures are required, the first method is inadmissible. A room with a southern aspect and many students receives air the same temperature as a north room with few occupants. Under these circumstances, the first will be too hot or the second too cold. Reducing the heat can only be done by reducing the air-supply. The difficulty can, jP/ie Ventilation of Schools. 83 however, be got over by having a number of auxiliary heaters attached to each room, which can either be used or not, and the propulsion system is then avail- able. Whatever system is used, it is necessary to have a separate heating surface to each room. Mr. Robins' review establishes the great advantage of extraction by fan, and though an exhaust chimney, heated by the flue of the boiler passing through it, is sometimes the only practicable arrangement, the amount of heat communicated to the shaft is not as great as calculation would lead one to imagine. In several instances it has proved insufficient, and a mechanical arrangement has had to be adopted for special rooms. In Chapter X. a description is given of a moderate-sized school, heated and ventilated by means of steam pipes. The question of who shall be responsible for the condition of the various rooms in a large school is one which frequently arises. The plan is adopted in some establishments of giving the masters or lecturers a key with which the heat can be controlled. This acts badly where the same room is used by various lecturers, whose tastes on the subject of temperature may be various ; but when one master remains in the same room for several hours, it is open to less objection. On the whole, it is better to have a caretaker, who will adjust the apparatus, if one of sufficient intelligence can be found. He should visit the rooms periodically, and be responsible, (1st) for the rooms being sufficiently heated in the morning before the school opens ; (2nd) for starting the ventilation apparatus, and adjusting the mixing valves or other mechanism provided, so that the incoming air should be of the right tempera- ture. What this temperature should be must be de- termined by experience. In a room scantily filled it may require to be many degrees warmer than the desired temperature of the room ; if the room be well tilled, considerably lower. Of course thermometers should be placed in every room, and the place for these 84 Notes on the Ventilation of Buildings. should be carefully chosen. They should, if possible, not be hung against the wall, which will probably be colder than the air in the room, nor anywhere near the heating apparatus. Any lecture-room which is but seldom used should Fig. 13. Extract and heating by steam (Leeds Boys' Modern School). have its outlet opening almost closed, except when it is used. By this means the ventilation arrangements of the other rooms will be more effective. With regard to chemical laboratories, an ample supply of draught chambers, and the enforcement of strict rules as to The Ventilation of Schools. 85 their use, will greatly relieve the ventilation require- ments. In the Finsbury Technical College, the Bunsen burners at the working-benches are fixed under an exhaust hood, and they cannot be used in other positions. Fig. 13 shows the method of ventilation and heating of a block of buildings at the Leeds Boys' Modern School. The upcast exhaust-shaft is heated by steam Fig. 14. Heating by steam, extract by fan (Yorkshire College, Medical Department). pipes in a chamber at the base, and the air is drawn down from the upper parts of the rooms. The air is admitted over steam coils placed against the walls, provided with the casing and mixing valve shown at Fig. 5. By this means the air can be admitted at any desired temperature. Fig. 14 shows a section of 86 Notes on the Ventilation of Buildings. the newly-erected Medical Department of the Yorkshire College, Leeds. The air is admitted over steam coils as in- the last example, but the exhaust is by a gas- engine, which actuates a " pressure " fan. The air is removed from the rooms at the lower part in the winter, and at the upper part in summer. The building was designed by Mr. W. H. Thorp, of Leeds, and Messrs. Ashwell and Nesbit of London undertook the ventilation and heating. Elementary schools in Targe towns are generally extensive enough to make it worth while to supply a proper scheme of mechanical ventilation. Consisting as these buildings generally do of a limited number of large class-rooms, the propulsion system here works well, and is strongly recommended by Dr. Carnelley in his report to the Dundee School Board. Dr. Carnelley's recommendations at the conclusion of his report are worth quoting in abstract, being as they are the result of a very complete examination of the question by a scientific man well qualified to judge. Recommendations. I. For new schools, mechanical ventilation should be employed. a. Because it is more comfortable, the temperature even, and draughts avoided. /3. It is healthier, and prevents the spread of in- fectious diseases. y. It increases the working and therefore the grant- earning power of the children, and the teaching power of the staff. The extra annual cost of mechanical ventilation is about 39 a year for a school of 1000 children, or 9Jd. per head. JI. A gas-engine (about 2 h.p. as a rule) should be used to drive the fan. III. A 48-inch fan should be used to propel and not exhaust the air. The Ventilation of Schools. 87 IV. High-pressure hot-water pipes should be used for heating, the pipes being placed in the air-chamber, and not in the flues. V. Arrangements should be made for mixing cold air with the hot, before the latter enters the room. Fig. 15. Ventilation of school. Steam extract and heating. (Billings.) (The same end may be obtained by arranging the hot- water pipes in sections.) VI. The air should be filtered through coarse jute cloth, placed diagonally across the large inlet flue, or across the air-chamber. 88 Notes on the Ventilation of Buildings. A special form of brick furnace is also described, applicable to high-pressure hot water. For small village schools or class-rooms the simplest method is by one or more hot-air grates, the air- passages being made of ample size, and arranged to deliver about six feet from the floor. An exhaust-shaft should be provided, in the form of a turret on the roof, with an exhaust-cowl, or a shaft running up parallel with the chimney. Sometimes a village school has a cottage for the mistress or caretaker attached. In this case the shaft may be made to adjoin the kitchen chimney of the dwelling-house, and will be warmed by the constantly burning fire in the latter. The windows should open with hoppers. CHAPTER XL THE VENTILATION OF HOSPITALS. THE provision of an equable flow of warmed air through the wards of a hospital is by no. means an easy problem. The rooms are occupied continuously day and night, and there are frequently more or less offensive odours to be carried off. It is generally agreed that not less than 3000 feet of air per head per hour should be given. Moreover, the usual shape of a hospital ward, a long oblong, has been fixed on mainly for the convenience of cross ventilation by windows on opposite sides, and does not lend itself readily to systems of mechanical ventilation. There are probably few buildings for which so many special systems of ventilation have been devised, or in which there have been so many failures. Hospital wards in England are generally sweet and free from offensive smells, but this purity of atmosphere is gained at the cost of numerous and unpleasant cold draughts during the The Ventilation of Hospitals. 89 colder part of the year, which patients greatly resent. " We have a regular fight with the patients about the windows," said a nurse in one of our large hospitals re- cently to the writer, and indeed the sufferers can hardly Fig. 16. Currents of air in hospital ward. Galton. be blamed. It should be possible to keep every hospital ward of whatever size perfectly sweet without the necessity of opening a single window, but it is very seldom that this can be done. No doubt the problem 90 Notes on the Ventilation of Buildings. is a difficult one with a long ward, though compara- tively easy in the case of the circular wards which seem to be coming into use. The diagram (Fig. 16) shows that even in a mechanically- ventilated ward there may be a stagnant area in the centre, though this could be considerably improved by making the ward lower, and fitting a more perfect diffusing arrange- ment to the inlets. Among the methods in use for hospitals may be mentioned that adopted at Victoria Park Hospital for Diseases of the Chest. Here a central exhaust tower, heated by hot-water pipes, draws air down a shaft some distance from the building into a double culvert in the basement, which runs the whole length of the building. One of these channels contains hot-water pipes, and the two are made to communicate by means of swing- doors, so that the hot and cold air may be mixed. The air rises through vertical pipes into the wards, and is delivered through gratings about three feet from the floor, and exhausted from openings just below the ceiling in a line above the inlet. On the whole the system works well, except in rather warm and close weather, when the difference of temperature within and without is not sufficient to cause an adequate draught in the exhaust-shaft. The inlets opening horizontally into the room cause a very perceptible draught to those near, and patients accordingly are prone to stop the openings with pillows or anything that is available. It would be better if the incoming stream of air were better diffused on entering, and in a part of the ward more remote from the exhaust. A very complete and successful system of mechanical ventilation is in use at the recently-constructed Victoria Hospital at Glasgow, where the propulsion system is used. The air is screened through a specially -constructed filter, designed by the engineers (Messrs. Key & Tindall) who carried out the work. The screen is kept constantly wet, and the air washed, not only the solid particles being removed, but also fog. The Ventilation of Hospitals. 91 The air is driven over heating coils, and admitted into the wards at the ceiling level, being removed at the floor level. There is some difficulty, however, in forcing air by propulsion to the end of a long ward. The exhaust system again is open to the objection that if a window near the outlet be open, most of the air will be drawn from the window, instead of from the end of the ward. Again, the ventilation being required equally day and night, the fan mast be constantly working, involving constant attention to the engine. This can easily be effected in a large establishment, but is difficult in a small one. The alternative is to furnish each ward with a separate exhaust, heated by gas or steam, or to take all the flues to a central chimney. Steam is often used to heat hospital wards, and then the coils should be furnished with the mixing- valve arrangement described in the chapter on warming. The heating of the ward is preferably done by open fireplaces, the steam being used only to warm the incoming air. Wards heated entirely by steam are apt to be oppres- sively hot and stuffy. The modern practice of building hospitals for infectious diseases in the form of isolated one-storeyed pavilions makes a central system impos- sible. There should be no difficulty in contriving an exhaust-shaft, heated by the fire of the kitchen range, which always forms part of the fittings of the pavilion. Small wards should have hot-air grates, with air- passages of ample size, large chimneys, and a chimney- breast ventilator. The windows should open inwards, on the hopper principle, but arrangement should be made to admit sufficient warmed air to render it unnecessary to open the windows. In connection with hospitals, the waiting-hall for out-patients requires very complete ventilation, and among the examples in a subsequent chapter will be found a method applicable to such cases. But the ventilation may be carried out on the general principles laid down with reference to assembly-rooms. 92 Notes on the Ventilation of Buildings. In the very extensive out-patient department re- cently erected at the General Infirmary at Leeds, the large waiting-hall is supplied with warm air by apertures beneath open steam coils, the smaller (examination) rooms are furnished with hot-air grates, and the larger (consulting) rooms are heated by open fireplaces, but there is a large inlet aperture, guarded by a steam coil with case and mixing- valve. The large hall has three roof turrets, which can be heated by gas, and the system on the whole is found to work well. The dispensary at a hospital is often the source of strange odours. The dispenser should be furnished with draught cupboards, like those in a chemical laboratory. The room should have an ample supply of warmed air, and a special exit. The following is the method of ventilation in use in military hospitals, as arranged by the Barrack Im- provement Commissioners, and the same plan is adopted also for the ordinary barrack-rooms. The size of the openings given are those in use in barrack- rooms ; those in the hospitals are nearly double the size. 1. A smooth, straight, wooden outlet-shaft is carried from the ceiling to six feet above the roof. This is not larger than one square foot in area. If a larger is required, two or more are put up. Ten to twelve square inches are allowed for each man, according to the floor on which the room may be situated. 2. Sherringham valves are fixed about nine feet from the floor, an inlet space of rather more than a square inch being allowed for every sixty feet of space in the room. The room is warmed by a "Galton" hot-air grate, which affords both an ingress of warm air and an outlet by the chimney. This system is said by Dr. Parkes to " work extremely well," but the author's experience is that the Sherring- ham valves are always closed in cold weather, and the inlet space is then not sufficient, The Ventilation of Theatres and Concert-rooms. 93 CHAPTER XII. THE VENTILATION OF THEATRES AND CONCERT-BOOMS. THE adequate supply of fresh air to so large* and elaborate a building as a theatre is a matter of such magnitude that an expert is likely to be consulted on the matter. There are few more perfect schemes of ventilation than have been devised and are now satis- factorily working at certain theatres. Notably, the Opera Houses at Vienna and Frankfort are instances of the kind. The Madison Square Theatre in New York is one in which the cooling of the air is very effectively done. There are also several theatres recently erected in London where mechanical ventila- tion is effectively performed. The Criterion Theatre in London is entirely below the level of the street, and lias therefore to be ventilated on the same principles as a mine. The arrangements for the heating and ventilation of the Vienna Opera House are singularly complete. They were designed by Dr. Bohm, the medical director of the Hospital Rudolfsstiftung. There are two fans, one for propulsion and the other for exhaust. The air is heated by steam coils, and is admitted by the floor and through the risers of the seats. Each gallery and compartment, including the stage, has its own inde- pendent supply and means of heating. The velocity of the entrance of the air is between one and two feet per second. The air is admitted to a basement chamber, into which, in summer, sprays of water are introduced ; it is then driven over the steam piping, and on into a mixing-chamber. The whole of the heating and the air-supply can be controlled from one central office, and by means of electric thermometers the officer on duty can ascertain the temperature of every part of the house. Very similar arrangements are found at the Metro- politan Opera House, New York ; but there is but one 94 tfotee on the Ventilation of Buildings. fan, and that is used on the u plenum " or propulsiori principle, which aims at producing a higher pressure inside the house than outside. This is designed to avoid draughts from the doors, which are so usual in theatres ventilated on the exhaust principle. The heating arrangements are excellently managed. The temperature of the house is kept at a high point during the day, with slow movement of the air, in order to warm the walls ; but when the house is about to be occupied, the temperature is dropped to that at which it is desirable the building should be maintained. As the performance goes on, and the warming action of the occupants becomes felt, the temperature of the incoming air is gradually lowered. There is found to be remarkably little difference between the temperature in various parts of the house, and there are special arrangements for regulating the hygrometric condition of the air. In former times there was great difficulty experi- enced in preventing the fumes from the foot-lights contaminating the air of the house, and few of the various kinds of exhaust-hoods which were placed over them worked satisfactorily. Now the use of the electric light renders gas foot-lights unnecessary, and greatly decreases the amount of air required for ventilation. Concert-rooms may be treated on the same plan as theatres, but owing to their being as a rule rather less crowded, there is less difficulty in supplying the air. Electric light being generally used, the heat from sun- burners which were generally used for lighting purposes is not now available for ventilation. Pro- pulsion by a fan seems the best method for this class of room, the air being passed over hot- water or steam pipes, screened, cooled, or moistened as required, and caused to enter the room at a height of seven or eight feet from the floor, by a number of openings. Outlets should be made near the ceiling, in such positions as will allow of the air being generally diffused. It is fhe Ventilation of Workshops. 95 convenient, even if the electric light be used, to have one or two gas-lights in the roof, of the ventilating type, in case of accidents to the electric supply, as well as in the corridors. The shafts belonging to these are available as exits for the main ventilation, and the exhaust from these would be sufficient to draw a small quantity of hot air through the building for mere pur- poses of heating, before the room was wanted for a concert. One of the g reat advantages of the propulsion method for rooms of this kind is that the current of cold air from the various doors, which is so unpleasantly felt in most concert-rooms, is reduced to a minimum. CHAPTER XIII. THE VENTILATION OF WORKSHOPS. THE legislature takes the sanitary condition of workshops under its supervision, and the inspectors of factories have directions with regard to gross faults in ventilation. By the Factory Acts "adequate ventilation " is prescribed. This is generally taken to signify 250 cubic feet of air per head in ordinary working hours, and 400 feet during overtime, a very insufficient amount. Three gas-burners are considered to be equivalent to one man. (This is an inadequate allowance, one gas-burner, as a rule, fouling more air than three men.) The Factory Inspectors are not trained sanitarians, . but they have the power of taking a Medical Officer of Health with them if they suspect matters to be amiss. They also have the power of ordering that a fan should be used, if there fce much dust arising from the nature of the work. In wet cotton cloth factories 600 cubic feet per head are to be admitted, and the " arrange- ments for ventilation shall be kept in operation, subject so far as possible to the control of the persons employed 96 Notes on the Ventilation of Buildings. therein." Inspectors are directed to examine into the temperature, humidity, and ventilation of such places. The temperature must not rise above 70 Fahr., and the difference between the wet and dry bulb thermometer shall not be less than 2. No specific instructions, however, are given to the inspector as to how he is to " examine into the state of the ventilation," no standard of purity of air being given, or directions for measur- ing quantity or velocity, or for performing chemical analysis. One weak point about ^these legislative regulations consists in the fact that none of the above provisions are applicable to private houses, where no power is used, and members of the family only are engaged ; and there is great reason to believe that a large number of such places exist, especially in the ready-made clothing trade, where a large family, with perhaps several apprentices, work in rooms not suited for the purpose, amid the most grossly insanitary conditions. Ventila- tion in workshops is a comparatively easy matter. There is always power available to work a fan, and steam for heating purposes. It is only necessary to make openings behind the steam-pipes to warm the incoming air. In some places an exhaust is readily made by means of a steam jet working in a properly- made tube, though this is very noisy. An attempt to ventilate by means of " ventilators " is always followed by the closing of the openings in cold weather. Printers are the most sensitive in this matter. They have to work largely at night, with a very strong gas- light. As a result the room becomes very hot, the men work with very scanty clothing, and the least breath of cold air is naturally resented. Any air which is admitted must be warmed, and hoods arranged to take away the fumes of the gas. The substitution of elec- tricity for gas will be an enormous improvement, from a sanitary point of view, in printing establishments. Successful Ventilation Schemes. 97 CHAPTER XIV. SUCCESSFUL VENTILATION SCHEMES. BEFORE giving a series of examples showing the application of the above rules to actual buildings, it may be well to refer to a few buildings in which a carefully-designed ventilation system is found to give good results. The Houses of Parliament have been referred fco before. When the House of Commons is not filled with more people than it was designed to hold, the ventilation is quite satisfactory. The motive power is here a shaft in the Clock Tower heated by a furnace, and this suffices for the greater part of the year, but in the summer months it is necessary to supplement this by an exhaust fan. The air is admitted over steam radiators, and the lighting is by gas placed above a glass roof, the fumes of the burners being led into the general exhaust-shaft. Arrangements are projected for substituting electricity for gas, but as the gas fumes do not enter the rooms, it will make no difference to the ventilation. Mention has already been made in the preceding chapter of the Opera Houses at Vienna and Frankfort- on-Main, where the air is heated by steam and propelled by a fan. In both these establishments a very perfect control is maintained, and the officer who superintends the sanitary arrangements can tell in his office the temperature of every part of the house, and lower or raise it as is required. In warmer climates the cost of cooling the air forms a considerable part of the expense. At the Madison Square Theatre in New York the arrangements are so perfect that with a temperature outride of 80 Fahr. the air discharged after passing through the house has a temperature of only 82. This is effected at an expenditure of six tons of ice per night. Very little attempt has been made to mechanically 98 Notes on the Ventilation of Buildings. ventilate churches, but the Fifth Avenue Presbyterian Church in New York has been much commended by authorities for its excellent arrangements. Sir Douglas Galton speaks of it as the best- ventilated church he has ever seen. In this building the air is drawn by a fan from the top of a tower and propelled through a heating chamber containing four sets of heating coils. There exists besides a system of steam-pipes which serve to warm the floor. The latter are used for twenty-four hours before a service is held, and on the assembling of the congregation the floor-pipes are turned oft' and the fan set in motion. Ventilation in most churches in England is entirely ignored. The new Church of St. Mary at Port sea, however, is an exception. A very perfect system of ventilation was projected for this church by an eminent engineer, including a fan, worked by a gas-engine, and a hot-water system for warming the air. Circum- stances arose, however, in the course of the erection, which rendered it impossible to carry out this scheme, and a far inferior plan was substituted. The air is admitted through apertures in the floor, and is warmed by means of furnaces. The latter are especially large, so as to prevent the heating surf aces being over-heated, and arrangements are made for an air-supply greatly in excess of that allowed for heating purposes only. In the lofty tower a large shaft has been made, which opens at the base into the church near the roof, and numerous gas-burners are placed here to heat the shaft. The system works, as a rule, fairly satisfactorily. Exception may be taken, however, to the plan by which the air is admitted through openings in the floor. In this case, unless the air is warmer than is necessary, 'unpleasant draughts are felt by those who sit near the openings : and when the whole of the furnaces are not employed, no air can be admitted from those which are not in use. Though the tower- shaft, as a rule, works efficiently, there occasionally Successful Ventilation Schemes. 99 occur conditions of wind under which the current is reversed, and there is actually a down draught from the tower. In a properly-designed mechanical system the force of the wind is combated by increasing the velocity of the propelling or exhausting fan. The last few years have seen a great activity in the building of large colleges, mostly for the purposes of technical education. As these institutions frequently include an engineering workshop, it has been easy to arrange a system of mechanical ventilation combined with heating by steam, and an interesting account of the practical working of a number of schemes of this kind is given by Mr. Kobins in the work above- mentioned. Among schools recently built may be named a suite of class-rooms, accommodating about 300 boys, erected in connection with the Leeds Mechanics' Institute. 1 Steam is used for warming, but there is no mechanical ventilation. The outlet-shafts from the rooms are collected and taken down to the base of a chimney- shaft in which is placed a quantity of steam-piping. Air is admitted to each room from the outside over steam coils, the heat of which is controlled by the mixing-valve arrangement described above. The upper floor (third storey), containing a chemical laboratory, is not included in this system, the rooms being ven- tilated by shafts carried well above the roof, many of which are heated by gas. On the whole, the system works well. The temperature of the rooms is easily controlled, and the atmosphere is changed about three times an hour. The chemical laboratory would no doubt be better ventilated by a fan, but there was reat difficulty in arranging for power to actuate it. n summer the exhaust is not in action, as the steam is not required for heating purposes, and ventilation has to be carried out by means of open windows. This is the weakest point of the scheme. For this reason, 1 Vide Fig. 13, p. 84. 100 Notes on the Ventilation of Buildings. even when steam is used for heating, it is better to actuate the fan by a gas-engine, or to heat the chimney by a special coke furnace. It is found also that, in rare instances, a strong wind will exercise such exhaust power on the lee side of the building as to reverse for a time the current in the exhaust-shaft. CHAPTER XV. EXAMPLES OF METHODS BY WHICH BAD VENTILATION MAY BE IMPROVED. IN the following pages a number of examples will be given illustrative of various kinds of buildings erected without any provision for ventilation, in which methods are proposed for the improvement of the sanitary condition. Most of these are from the actual experience of the author, and illustrate failures as well as successes. It must be clearly understood that in few of these could really perfect ventilation be secured, but so great an improvement was produced that the trouble and expense of the alterations were amply justified. It may be premised that nothing can be done without the expenditure of money, although an opinion to the contrary is very prevalent. "Venti- lators " can be bought cheaply, but not ventilation. Example 1. A church seating 400 persons, with nave and aisles, clerestory windows, some of which open ; lighted by gas-pendants ; warmed by hot-water pipes in channels on the floor ; no openings for admission or egress of air ; a western tower of moderate height. Suggestions. (1) Make inlet apertures at the ground level on each side (two at least say 2 ft. by 18 in.) at the eastern portion of the nave, and place in front of these hot-water coils. As this will certainly overtax the boiler, arrangements should be made by which the flow to the floor-pipes can be cut off as soon as the Methods for Improving Bad Ventilation. 101 building is warm, and the force of the fire directed to heating the " ventilating coils." (2) Make an opening, say 3 ft. by 4 ft., from the church into the tower at the level of the roof, and enclose by means of lath and plaster a shaft running to the highest point of the tower. This may open into tlie belfry, or be carried to the top of the tower and capped by a cowl. Place a number of gas-jets at the base of this shaft. A door must be fitted to the opening into the church, to be kept shut when no ventilation is required. (3) Reduce as far as is possible the consumption of gas by the following methods (i.) Fix a regulator on the main pipe, and remove the weights until the gas-flame is just steady. (ii.) Substitute so far as is possible a few large burn- ers for several small ones. This can be done with greatest advantage when the pendants or brackets are fitted with triple lights, one vertical and two horizontal. Remove entirely the two horizontal ones, and substitute for the central burner one burning half as much gas as the three together ; e. g. remove three burners (Bray's "Regulator/' No. 3, is the most usually employed burner), each of which at one inch pressure will give the light of about seven candles, with a consumption of five feet of gas, and substitute one No. 5 " Special," which at the same pressure will burn about seven feet with the light of twenty candles, a saving of about half. For summer ventilation, at least half the clerestory windows on each side should be made to open. The lower windows should be fitted with hoppers, so that the incoming air has an upward tendency, and advan- tage should be taken of any window comparatively remote from the sittings to admit as much air as possible. All windows and doors should be open for half-an-hour at least after every service ; then (in winter) closed in order to allow the building to become warm ; but the pipes which are only used for heating 102 Notes on the Ventilation of Buildings. should be put out of the circuit before service is com- menced. Air may also be conveniently admitted by making the inner porch or screen which generally protects the door open at the top, the outer door being left open, so that air is admitted about eight feet from the floor. Rules will be found in Chapter XVI. for calculating the size of the inlet openings, the shaft, and the amount of gas required to heat it. It is most desirable that the heating apparatus in a church should be kept con- stantly alight. It is very difficult to properly heat a large stone building in a short time. The difference of cost between warming a building for Sunday use and keeping the fire going the whole week is only an excess of one-third in the amount of fuel consumed. This excess will to a large extent be covered by the dimin- ished cost of keeping the organ in repair, and avoiding other damage by damp. To make a building of this kind really satisfactory, a new heating apparatus of larger capacity will be required. Example 2. A substantially-built brick mission-room, with windows at the sides and one end ; open roof ; heated by a stove and lighted by gas-pendants of " star " form. This is a much more difficult room to render healthy, inasmuch as there is no tower. The stove is probably utterly insufficient to warm, if there be any adequate change of air. For inlets, cut a large hole in the wall behind the stove, and place screens of sheet iron on each side of it, in order that the air may impinge on the heated sur- face. The question of having a larger stove will be considered, or additional heat may be obtained by means of gas-stoves. The "drying-room stove," by Fletcher & Go. of Warrington, is a good one for this purpose, and should be placed in front of a large opening in the wall, or the opening may be made to deliver underneath the stove. The chimney, which is small, may be run up the wall and through the roof without being unsightly. One large ventilating cowl Methods for Improving of the usual "exhaust" type should be placed on the ridge of the roof, in such a position that a high- power gas-burner, furnished with ventilating-tube, can be placed underneath it, the tube to run up into the cowl. Two high-power burners would be sufficient to light a room of this kind, and it would be ^better if both could be connected with the roof ventilator. The windows should open with hoppers, as in the previous case, and there will be no need of any special inlet ventilators. An iron church or school of the same type may be ventilated on similar principles. Appearance here is, as a rule, little considered, and as the building is generally a temporary one, probably the best way of heating it would be by gas-stoves of the tubular pattern, such as those made by Fletcher & Co. These should be placed against the sides of the building, near the entrance, with large apertures behind or under- neath them ; the flue-pipes should be carried up inside the roof, to open at the top. At the other end of the building place an outlet cowl, connected if possible to a ventilating-pipe from one of the pendants. The inlet apertures should be closed while the building is being heated, but the convenience of gas is that it may be kept low and the building prevented from getting very cold, without the attention required by a fire. It is, however, for continuous heating, about six times more costly than coke. Under rip consideration are gas-stoves to be used to heat any inhabited building unless provided with a flue. Many stoves are sold for the purpose, as " requir- ing no flue." This is a fraud. So-called "condensing stoves " simply condense a little water. The foul fumes from gas cannot be condensed, and no room is healthy in which gas is burnt (for any purposes) for lengthened periods without a chimney. As heat is nearly as keenly felt in an iron building as cold, a perforated iron pipe may be run along the ridge of the roof, and a gentle stream of water allowed 104 Notes on tJie Ventilation of Buildings. to run down. The cost of the water is insignificant, and the relief great. Example 3. An extemporized mission-room, con- structed out of two cottages. A low room, with two windows, two doors, a fireplace, lighted by two or three gas-pendants or brackets, or by paraffin lamps hung against the walls. It is very difficult to make a room of this kind healthy or comfortable if crowded. The heat from the occupants is so great that no stove is tolerated, except in the coldest weather. Something can be done by making an aperture into the chimney at the level of the roof, or into both chimneys, if, as frequently happens from two rooms having been knocked together, there be two. One of the gas-brackets or lamps used to light the room should be fixed on the wall a little below this opening. The windows should be made to open inwards, or, if they are sashes, a hopper can easily be extemporized, by placing a piece of wood resting on the sill, hung with chains so as to incline inwards. If there be means of placing a stove (burning either coke or gas) against an outside wall, a hole should be cut in the wall behind the stove, as in the preceding example. Such rooms should never be used for more than an hour without being vacated, and all the windows opened. As a matter of fact, it is impossible to render them healthy, and from a sanitary point of view they are not to be tolerated. Example 4. A Sunday-school class-room. Of good height, heated by an open fire. A good deal here depends on the kind of fireplace. With an open fire the room never becomes as offensive as when a stove or hot water is used to heat ; and an open fire is infinitely the best way of heating and ventilating a small room. But with a quick combus- tion fireplace of the ordinary type there will be, in cold weather, draughts from all the windows. With a slow combustion grate there will be insufficient ventilation. Probably the best fireplace is one of the " ventilating " Methods for Improving Bad Ventilation. 105 or "hot-air" type, such as the Galton, Boyd, or one recently made by the Teale Fireplace Company, of moderately quick combustion. This introduces a brisk stream of warmed air, and acts as an inlet venti- lator even when the fire is not lighted. The windows should be arranged to open inwards on the hopper principle, and a chimney- breast ventilator be placed at the level of the ceiling. For a room 18 ft. by 16 ft. a three-light " Stott Thorp" or "Harrison " light will be sufficient as a pendant in the centre of the room, it being understood that there is a governor on the main gas-pipe. For these lights the governor should be adjusted to give a pressure at the burner of 7 8 -Q inch (water gauge). Example 5. A long, lofty room, with glass roof, riginally built for a picture-gallery. Windows in the roof will open. Heated by hot-water pipes round three sides. Now used as a class-room for mechanical drawing. Lighted by a double row of small gas-jets, besides which there are about thirty shaded table gas- lights for the use of the students. This room was perfectly intolerable in winter. The roof ventilators could not be opened without causing icy down draughts. The room became oppressively hot and very stuffy, and the condensed moisture fell from the glass roof in large drops on the students' drawings. The following changes were made 1. The rows of gas-jets above were taken away and the room lighted by two high-power (100 candle) burn- ers, furnished with reflectors and ventilating-tubes, which passed through the roof. 2. The table lights, which were of the common type, and too large (Bray's " Regulator," No. 5), were replaced by better (Bray's " Special," No. 1), which gave a sufficient light, with a consumption of three feet less gas apiece. This saved about ninety feet of gas per hour, with its attendant impurities. Two inlet venti- lators were placed on the outside wall of the room, at points most remote from the students' desks. 106 Notes on the Ventilation of Buildings. Result. The room is by no means perfectly ventilated, but the atmosphere is quite tolerable even when it is well filled. There is no condensation of moisture, and the only gas-fumes which are not carried away are those inseparable from the table lights. Great relief has been expressed both by teachers and students. But to make it really comfortable, there is required a larger inlet for warmed air. Example 6. A room 30 ft. by 50 ft. Used as a design- ing room in a school of art. Lighted by three windows at one end, and small circular lights along one side. The room is rather dark except at the end nearest the windows, but is used mostly at night. It was lighted at night by two small high-power burners at the inner end, and a number of table lights with shades over the rest of the room. The atmosphere of the room was very oppressive from the strong smell of burnt gas. It was heated by hot-water pipes. Two hit-and-miss ventilators at the window end near the floor were found (as usual) to be stopped up. It was impossible here to dispense with the table lights, but the two high -power burners were replaced by one larger one. It was found possible to run a fourteen-inch zinc tube through the inner wall of the room close to the ceiling vertically up into the open air above the roof, one storey above, where it was capped by a cowl. Into this tube the ventilating-pipe of the larger burner was conducted, in order to cause a draught. The windows of the outer end of the room were arranged to admit air between the sashes, on the "Hinkes Bird" principle, described in an earlier chapter. The hit-and-miss ventilators on the floor were led into vertical tubes about five-and-a-half feet high. Result. In moderate weather, especially when the windows can be kept a little open, the room is com- fortable. In very cold weather there is a draught felt from the windows and inlet tubes, but not so great as might have been expected ; the descending current of cold air being partly heated by the ascending hot Methods for Improving Bad Ventilation. 10? air from the table burners below. The room would be improved by the fixing of a hot-water coil under the windows, with a large inlet behind it. The exit-tube acts very well, and the general improvement in the room is very great. The following example (7) illustrates well not only faults in construction, but faulty methods of improv- ing the same, due to ignorance of the laws affecting air currents. A lecture theatre measuring 32 ft. by 22 ft., with a high staging for students, accommodated classes of about 50. The architect had made a shaft running along the ceiling 12 in. by 8 in. in area, communicating with the room by a few small holes, and open to the air at each end. There were two outside walls, and the space below the seats, in which was a large hot- water coil, opened by a door into a passage running along one side. It is almost needless to say that there was no ventilation at all. The shaft on the roof was utterly useless. There was no inlet. Subsequently a Slierringham valve was placed near one corner of the room, but this made very little difference. A maker of ventilators was now consulted, who placed two inlet valves on the outer wall, behind the lecturer, and a third on the wall adjoining the passage. From this latter a tube about 8 in. by 7 in. was carried, with a right angle bend, through the roof into the air. Fu rther, the shaft in the roof was connected with a long hori- zontal tube, which, after a bend at right angles, was taken a considerable distance vertically upwards through the roof, where it terminated in a "patent exhaust ventilator." Examination of the room after these alterations were made, showed that the ventila- tion was still very defective. A certain amount of air was admitted by the two valves on the outer wall of the room, but the other valve, with its tube attached, and the tube in the roof, were practically inert and useless. This is precisely what might have been expected, the length of the tube and the right-angle 108 Notes on the Ventilation of Buildings. bends causing such friction that practically no air passed. Eventually the room was improved by further measures. The door leading to the space beneath the staging had its lower panels replaced by perforated zinc, and one of the skylights was made to open. The latter could not be kept open in winter on account of the cold down draught, but served admirably to clear the room of foul air after a lecture, before the next began ; but the result of making an opening in the door at the panel near the ground level was that a steady stream of air entered by this inlet, and becoming warmed by the hot-water coil, was not felt as a draught. The exit on this system was by one or more of the inlet- valves in the upper part of the theatre. Example, 8. The following instance of the difficul- ties experienced in ventilating a large reading-room and library in a public institution affords a good example of what may be done under very unpromising conditions. The room, long and lofty, formed one corner of the building, thus consisting of two parts at right angles to each other. It was lighted by a number of three-light gas-pendants, and a few table lights, and warmed (insufficiently) by hot- water coils. There were small apertures above the gas-pendants leading to tubes which passed horizontally into the air. There was a circular window near the ceiling communicating with a vestibule. When the gas was lighted and the room moderately full the atmosphere was very bad, and caused great complaint. An agent for Tobin's ventilators was then commissioned to insert some of these tubes. About twelve of these were fixed, aper- tures being cut through the window-frames. The windows were large casements, and caused such draughts when open that they were invariably closed. These ventilators, however, were only 9 in. by 3 in., and the tube contained two right angles, so that they were practically useless, and made no real impression on the atmosphere of the room. The following measures were now taken : Methods for Improving Bad Ventilation. 109 1. The hot-water piping in the room was greatly increased, and a special coil erected at the end of the room adjoining the vestibule. Behind this three aper- tures were made, one foot square each, and a wooden screen was erected in the room in front of the coil. 2. Two metal tubes, 12 in. by 6 in., were led from the ceiling level through the wall into a staircase, and vertically up to the roof, and capped by cowls. At the lower end of the tubes gas-burners were placed. 3. At opposite sides of the room, i. e. on the outer wall of each portion, a hopper window was constructed. 4. Gas-burners of improved construction were fitted to the pendants, and the gas supply carefully regulated. None of these alterations except the increase of the heating surface involved much outlay, and it is in- structive to note the result. The atmosphere of the room is very greatly improved. The exit-shafts heated by gas take away a very con- siderable amount of foul air, but it is to be regretted that they were not thrice the size. There is a good supply of fresh warm air from the large opening at the end of the room. The principal improvement, however, is due to the large amount of hot-water piping, which so warms the room as to allow of the doors being kept open, except in very cold weather. The doors are some distance from any of the seats, and there is an inner screen. On the other hand, the hopper windows give rise to such draughts that they are hardly ever opened. In point of fact, the places were badly selected for their insertion, and there are no doubt positions in the room in which they would do good service. Were the gas replaced by electric light, there would be very little to complain of in the con- dition of the room, as it is not, as a rule, largely filled by occupants. As usually happens, the draught does not always set in the same direction. A strong wind against the side of the building opposite the principal inlet will drive the air out through the latter, entering by the Tobin tubes, but this does not often occur. 110 Notes on the Ventilation of Buildings. Example 9. A large square room capable of seating about 100 people, and used principally for meetings of a scientific society, about sixty in number. It was warmed by an open lire, and lighted by a large gas chandelier of about twenty lights. The room became very hot and the atmosphere extremely offensive in a short time, even when only a small number of persons occupied it. The first step was, as usual, to introduce some patent ventilators. Two inlet valves were inserted, the in- ventor and patentee stating that they would give sufficient air for 100 people. As these openings were about 64 square inches each in area, the previous esti- mate of fresh air actually required must have been de- cidedly economical. A mica flap ventilator was placed in the chimney. These measures could hardly be said to make any marked difference in the state of the room. Eventually the matter was more seriously taken in hand. The chandelier was removed and a sun-burn dr, with proper ventilating-tube, substituted. An opening 2 ft. by 1 ft. was cut in an outside wall, at a point the most remote from the fire, and a steam-coil placed in front, and enclosed in a wooden casing lined with zinc and felt, and open at the top. There are now two exits, viz. the chimney, and the ventilator of the sun- burner. The large inlet (two square feet) can be kept open in the coldest weather, and provided there are not more than about sixty persons in the room, the atmosphere is fairly good. Example 10. The waiting-room for out-patients of a large public dispensary, accommodating about 200 persons. Twice a day this room was filled by an un- washed crowd of sick. The room was badly warmed by two open fireplaces, one at each end. There were two large Tobiii tubes, and two shafts in the ceiling running up to the top of the roof into a suitable cap. There were plenty of ventilators, but 110 ventilation. The Tobin tubes were invariably closed, as they caused Methods for Improving Bad Ventilation. Ill cold draughts, and the exhaust shafts were of no use without them. By way of improvement the fireplaces were disused, and a large Musgrave stove placed near the centre of the room, the flue being led into one of the chimneys. An air-duct 2 ft. by 1 ft. was run under the floor from an outside wall, opening underneath the stove. The stove was purposely a very large one, in order that the fire might not require urging, and the stove never get very hot. This alteration was followed by very great im- provement, large quantities of air entering by this duct, and the exhaust-tubes in the roof acted satisfactorily. Appearance in this case was not considered. Had it been necessary to avoid anything of an unsightly nature, the same effect could have been secured at greater cost, by placing hot-water coils against inlets on the outside wall. The stove, however, was by far the cheaper method. Example 11. A dining-room in a private house, 20 ft. by 18 ft. It was lighted by a central four-light gas pendant, and there were gas-brackets on each side of the chimney-piece. There was an ordinary fireplace. The room became inconveniently warm and oppressive very soon after the gas was ignited, and there were draughts from the windows. The first method adopted was to substitute a slow combustion grate for the one in use. This did indeed mitigate the draughts, but made the room more oppressively stuffy than before. Next an inlet ventilator was inserted, but in cold weather this merely renewed the draught nuisance. The matter was then taken in hand in more scientific fashion. The four-light pendant, consuming about twenty-four feet of gas per hour, was replaced by one Regenerative burner, which consumed six feet only, and the brackets were fitted with regulator burners, consuming four feet each instead of seven. The gas consumption was thus reduced to fourteen feet from thirty-eight, with an equal amount of light. An open- ing was made in the ceiling and a ventilating-pipe run 112 Notes on the Ventilation of Buildings. into the chimney ; the ventilating-tube from the central burner being connected with this. An opening was made above the inlet of the door whereby air was admitted from the hall, which was heated by a stove. This involved some structural alteration and some expense, but the saving in the consumption of gas amounted to about two shillings a week. Example 12. A lecture hall, holding about 400 people, had and still has an evil reputation for its in- sufficient ventilation. It was lighted by gas chande- liers of the usual type, with nearly horizontal burners, and warmed by hot- water pipes beneath the staging. The following measures were taken to improve matters, but with very little effect. 1. The gas-pendants were disused, and the room lighted by electricity. 2. A number of shafts (seven or eight) about 2 ft. by 1 ft. were taken from various parts of the room up to the roof, and gas-burners placed at the entrance. 3. A number of Tobin tubes were placed on the outside wall. The result is interesting to observe as a warning. There is no arrangement for admitting warmed air from beneath, consequently the numerous exit-shafts are almost entirely useless. Some do carry off a little foul air, others act downwards and admit a small amount. The Tobin tubes are as usual always closed. The case illustrates what has been said before as to the evil of several outlets, and the uselessness of exit-shafts unless proper arrangements are made for admitting a due supply of warmed air from beneath. The most efficient way of ventilating such a room as the above would be by a small fan which should take air from the outside and propel it over the heating apparatus into the room. This could easily be actuated by an electric or hydrau- lic motor. The above examples give a general idea as to the kind of measures which are likely to improve insanitary rooms, as well as those which have been found useless. Methods of Calculation, Formulce, etc. 113 There is no royal road, and no invariably successful system. There are often three or four ways of securing ventilation, any of which may be successful. Which of them should be adopted is generally a question settled partly by pecuniary considerations, partly by v local circumstances, which vary in every case. The greatest caution should be exercised in receiving the statements of persons, either unskilled or interested, on the merits of any ventilation arrangements in actual use. The only evidence which is of any value is the measurement by experts of the amount of air actually being passed through a building, and an analysis of the air, when the building has been occupied for at least an hour. Speaking generally, as a test for un- skilled persons, the complete absence of any abnormal odour or excessive heat when the room is entered by a person fresh from the outside air is the only evidence which should be trusted. We live in an age of venti- lators, it is to be hoped that this is the precursor of an age of actual ventilation. Sir Douglas Galton has well said " If the opinion was only equally spread through the community that bad air was detrimental to health ; if the fact of a room being close or stuffy was regarded as disgraceful ; if people refused to attend dinner- parties where the rooms were filled with bad air : the architects, the builders, and the occupiers would soon find means that every room should be pure and of a comfortable temperature." CHAPTER XVI. METHODS OP CALCULATION, FORMULA, ETC. VENTILATION is an exact science, admitting of exact results, under varying but still quite well-known con- ditions. Except, however, in schemes worked out by practical engineers, where a definite steam-power is H 114 Notes on the Ventilation of Buildings. used, it is very unusual to find that any sort of calcu- lation has been made. Sizes of openings, flues, &c. are guessed at in the roughest possible way, and builders and designers seem to have very little idea of the real capabilities of the apparatus they make or purchase. Easy as calculations of this kind are to the skilled engineer, they appal, by the very appearance of the mathematical formulae, those who are not accustomed to deal with figures in this way. For a fuller treat- ment of this subject the reader is referred to the engineering manuals referred to in the Appendix ; the following examples, adapted mostly from those given by Box (Practical Treatise on Heat) and Bacon (Tech- nical School Building: Eobins), are merely given to show the general way in which the recognized factors for good ventilation work are obtained. It is most important in considering the size of flues, inlet openings, 238 = 59. The amount of heated surface required to raise the air to the necessary height would be according to standard authorities a Steam-pipes at 240 ...... 46 square feet. /3 Hot-water pipes at 150 ... 112 7 High -pressure hot- water pipes at 237 ...... m ... ... 61 The heating surface might be placed in a chamber below the floor, or against the walls of the room, covered in front and at the sides, open at the top, and the air admitted about 5 to 6 feet above the floor. Extraction. The size of the extract shaft would depend on the available height, and the temperature to which it was raised. Let us suppose it is desired to adopt a simple shaft, open to the top of the building, say 40 feet in height, not artificially heated. Taking the temperature of the shaft as 60 and the outside air at a mean of 50, we may calculate the size from the following formula =V 0'5 J-rhT Where D = Diameter of flue necessary. N = Number of persons. d = Difference between internal and external temperatures. Methods of Calculation, Formulce, etc. 117 If the calculation be on the basis of allowing 1000 feet per head, the formula stands D = V "W,^ Putting in the values here we have D = 41 - . ee ' or on tlie " ^ ' 6 v /4o"x~lo basis T55 feet. This will perhaps be an inconveniently large shaft. If however we can arrange to heat the exit-shaft, we shall exercise considerable economy in its size. As an example of this and of another method of calcu- lation, we may take a case where we have a large central exhaust heated by the chimney of the boiler passing through it, taking the room as one of 6, witli a total required exhaust of 172,200 cubic feet per hour, assum- ing the mean temperature of the smoke-flue as 300, and the height of the shaft as before, 40 feet ; the external diameter of the smoke-flue as 12 inches ; the mean temperature of the air entering the shaft as 54 ; we may calculate the mean temperature (T) of the up-cast shaft by the formula *- 1 = * + w Where s = Surface of heating flues (square feet). (Here 125'66 sq. feet.) t' Temperature of ditto. to = Weight of air in Ibs. passing up shaft per- il our. T' = Temperature of external air. We have therefore T - KA J. 3 X 125 "66 (300 -54) _ 6 X 2191 V = 0'18 x/TF = 018 fj 40 X 6'9 ~~ = 2 '99 feet per second. 118 Notes on the Ventilation of Buildings. The area of the main shaft would be 172200 0'785 + 2 7 97 ' 18 J or a diameter of 47 ft., the flue occupying 785 square feet. If we take the mean of winter temperature 39*6, a much greater advantage would be gained, while in many cases a greater height than 40 feet would be obtainable. Example 2. A chapel with 400 occupants on floor and gallery. An allowance of 500 feet of air per head per hour, with an external temperature of 30, and an internal temperature of 60. Heat will be required (1) To warm the walls. (2) To heat the air required for ventilation. 1. Area of walls about 3313 square feet, with about 41,081 units per hour. Windows, say 20 (6 ft. by 4 ft.), will lose 5904 units, together 46,985, or say roughly 47,000 units. When the building, however, has been raised to its standard temperature, a smaller amount of heat will be required to maintain it. The walls lose only 4'96 units per foot instead of 12, and the total loss by the walls will be 16,432 units, and by the window's 5904 ; making for both sources 22,336 units instead of 47,000. 2. Heat required for ventilation. Allowing 500 feet per head per hour, we require 200,000 cubic feet or 15,220 Ibs. of air. To raise this from 30 to 60 we require (15,220 x '238 (60-30)) = 708,670 units, making with that required to keep the room warm (22,336 units) 131,006 units. From the 400 occupants 76,400 units are available, leaving 54,606 units to be supplied by the heating aparatus. This would require 356 square feet of surface heated by hot water at 150. In this example the chapel is supposed to have galleries, and the occu- pants are packed rather more closely than is usual in modern churches. This state of things resembles that which prevails in a theatre, for the ventilation of which Mr. Bacon (Robins, op. cit.) gives the following formula Methods of Calculation, Formulae, etc. 119 \j _ 191 a-** Where a = Number of persons DIBIT Cf-fl present. d = Loss of heat at fixed difference of temper- ature per hour. T = Temperature of air at entry. t = Normal temperature of building. V = Volume of fresh air in cubic feet per hour. Mr. Bacon points out that such buildings require a considerable amount of cooling, and recommends that the air be introduced 15 below the temperature of the room. This, however, seems very low, and would hardly be tolerated. The case must be considered of a building of this kind only half filled. Then there would be only half as much air required, and the amount of heat needed for this purpose would be only half that calculated for the full room. On the other hand, there would be only half the heat supplied by the audience, so that practi- cally we should find that nearly as much heat was required from the apparatus as when the room was filled. The draught-chimney in this case would require to be partially closed, or the heat by which it was actuated moderated, or in the case of a fan, the velocity diminished. The draught-chimney, if 30 feet high, with an exter- nal summer temperature of 72, may have the air heated 30, or to 102. This balances 30 x ' = 28'4 feet of external air at 72, that is to say, 1*6 feet of unbalanced pressure, which will generate theoretically a velocity of tj T6 x 8 = 10 feet a second. This may be taken practically at about half, or 5 feet per second. 200,000 cubic feet of air at 72 is dilated at 102 to 200,000 x i.Qg.2 = 211,300. Hence by the preceding formula the 120 Notes on the Ventilation of Buildings. area of the chimney must be 58 in. by 5 in. = 11 '6 square feet, or 3 ft. 5 in. square. If it is proposed to heat this chimney by gas, 200,000 cubic feet or 14,940 Ibs. of air require (14,940 x 30 x '238) = 101,672 units, to raise it 30. The audience, however, will supply 76,400 (see above), leaving 25,272 units to be supplied by the gas. This, taking gas at 580 units per foot, requires 44 feet of gas per hour, costing, with gas at 3.s., about 2d. The area of the inlet openings may be calculated by a similar method to that by which the area of the out- let is obtained. We shall not be far wrong, however, if we allow an inlet space equal to the calculated outlet. The late Dr. De Chaumont, as the result of his experiments, gave an estimate of 125 cubic feet per inch of area, as the maximum likely to be passed under ordinary circumstances. In an example worked out by Box (Treatise on Heat), 93 feet per inch is calculated in the case of a school ventilated by a heated air-shaft. It will be seen that to work satisfactorily a scheme of this kind considerable skill in management will be required. The draught-chimney is working at its greatest disadvantage in the hottest weather, and will extract a much larger amount in winter. The draught in the colder weather must then be checked, preferably and most economically by restricting the amount of gas burned ; the heating surface having been calcu- lated for the coldest weather. During the warmer part of the winter season, arrangements must be made to control the heat by one of the methods described in the chapter on warming apparatus, not more than two-thirds being required as a rule. It is quite possible to make automatic self-regulating heating and venti- lation machinery, and the ingenuity of American engineers has contrived very perfect ways of effecting this. The master of the house can move a dial in his hall, and the temperature of the house will be kept at the point indicated by the dial. This is done at no Works on Ventilation. 121 very great cost, and the arrangement would save a great deal of trouble. 1 But, speaking generally, a certain amount of intelligence will be required to work the apparatus which is constructed, and the provision of such intelligence is often more difficult than the planning and carrying out of the whole scheme. Still a great deal can be done if the conditions required are really understood and explained to the attendant who has to work the apparatus. There is one point, however, connected with comfort of rooms, on which it is feared there must always be some difference of opinion, viz. the temperature. Older people like high temperatures ; younger people prefer rooms cool. It is seldom that the same temperature will suit every one : and so a school-room with an elderly teacher is often kept too hot for the efficient activity of the scholars. This difficulty must be boldly faced, and a consensus arrived at, in case of difference of opinion, as to the temperature which suits the majority. CHAPTER XVII. WORKS ON THE SUBJECT OF VENTILATION. THE following works may be consulted by those who wish for further information on the subject of ventila- tion. The most exhaustive treatises on the subject are those by (1) Gen. Morin, Etudes stir la Ventilation, Paris. (2) Peclet, Traite de la Chaleur, Paris. An interesting historical account of ventilation experiments of former years is given by (3) Tomlinson, Warming and Ventilation, London, 1886. 1 The " Powers Thermostat," made by the Toronto Radiator Co (Toronto), seems well adapted for this purpose, and can be fitted to any form of heating apparatus. 122 Notes on the Ventilation of Buildings. (4) Most important practical information is contained in the Practical Treatise on Heat, by Thos. Box, London, 1885, which is a manual for engineers of great value ; but, from a physiological point of view, the estimate of ventilation requirements contained therein is very low, and entirely inadequate. (5) Excellent also are the articles by Bacon in Robins' Technical School and College Building, London, 1887. (6) Galton, Healthy Dwellings, Oxford, 1880, and articles by the same authority in the Health Exhibition Reports, may be consulted. (7) Putnam (The Open Fireplace in all Ages, Boston, 1886) gives an interesting account of open fireplaces, ancient and modern, and American methods of heating by hot air, with reference to ventilation. (8) The Principles of Warming and Ventilation, by Dr. J. S. Billings, London, 1884, and New York, 1893, is one of the most valuable works on the subject ; but the examples and general methods recommended are adapted to the climate of the northern States of America rather than that of the British Isles. (9) Carnelty. Report on the cost and efficiency of the heating and ventilation of schools. (323 schools examined.) Winter, Duncan & Co., Dundee. 1889. (10) Ritchie. Treatise on Ventilation. 1862. (11) Dictionary of Engineering (Spon.). Art. Ven- tilation. (12) Shaw. Warming and Ventilation. A very able article, from the engineer's point of view, in Treatise on Hygiene and Public Health, by Stevenson & Murphy. 1892. Vol. I. (13) Drysdale and Hay ward. Health and Comfort in House-building. 1872. (14) Phipson. Proceedings of Institute of Civil Engi- neers. Vol. IV., 1879, p. 124. On the heating and ventilation of Glasgow University. (15) Constantine. Warming and Ventilation. This is practically a trade advertisement of a particular kind Appendix* 123 of heating apparatus, but incidentally some interesting information is given respecting the ventilation of public buildings in Manchester. (16) Engineering Record (American). 1892. For schemes of automatic temperature regulation in con- nection with mechanical ventilation. APPENDIX. Conspectus of the state of the air in 85 schools mechanically and " naturally " ventilated, by the late Prof. Camelly (Journal of Pathology, Nov. 1893). TABLE I. Rooms examined. Percentage of windows open. CO2 in vols. per 10,000. Micro- organisms per litre. Natural ventilation : Country Suburbs and country towns 45 46 24 32 161 167 76 103 Town (Aberdeen) ... Town (Dundee) 42 39 28 22 18-8 18-6 136 152 Mechanical -ventila- tion : Town (Aberdeen) ... Town (Dundee) 12 25 3 12-3 12-3 20 17 124 Notes on the Ventilation of Buildings. TABLE II. Kesults classified according to method of heating. Rooms ex- amined. Windows open, per cent. Excess of organic matter. CO'-* i n vols. per 10,000. M icro- organisms per litre. 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