Compilation, published by Robert Boyle & Son, Ltd.

“ In order to keep down the percentage of pollution to a non-dangerous degree, under this system arises, therefore, the necessity of admitting for ventilation fresh air in quantities many times greater than that actually used for breathing, and also a correspondingly extravagant expenditure of heat if this supply be artificially warmed. Thus the only ideally perfect ventilation consists in inducing a regular upcurrent from a level below that of the human head up to the extraction outlets at the ceiling. ”

“ Wherever a building is occupied permanently with definite conditions it is far better to trust to the ventilation of Nature—natural ventilation—than to the artificial pumping in of air. During that part of the year when the windows can be opened, at least fifteen to twenty times as much fresh air would be admitted into the ward, per patient, than could be obtained if the air was pumped in, as in the Birmingham Hospital, and that was certainly much more beneficial to the patients. I visited the Victoria Hospital at Glasgow, and went through the wards. ”

“ A high authority fixes 100 cubic feet per hour per person as quite sufficient with this method of ventilation, as the average of 20 cubic feet of air which is respired by an adult per hour is expelled from the lungs at a temperature of 80° to 100°F., and ascends, along with the heated exhalations from the body, to the upper parts of the building, and is there at once drawn off, so that no part of the vitiated air can be returned to be rebreathed, as is the case when the ventilation is effected by dilution by impulsion, particularly when on the downward principle. ”

“ A scientifically arranged system of natural ventilation may be described as the application of means by which the natural laws of ventilation can be effectively brought into operation, the power which operates in producing the currents and change of air being as constant as gravity.
" Incessant movement of the air is a law of Nature ; we have only to allow the air in our cities and dwellings to take share in this constant change, and ventilation will go on uninterruptedly without our care. ”

“ The fact of your appliances being entirely self-acting and having no movable parts liable to get out of order after having been placed, is a great boon, as it renders any after cost or attention unnecessary. During the time that I have devoted to testing your appliances I have always found them entirely free from downdraught, a feature I have not found in any other system, and which I opine to be of the greatest advantage, as it not only serves to ventilate the building more thoroughly, but furthermore maintains an even temperature therein, which no sudden change of weather can affect. ”

“ If, therefore, the inlets and outlets be properly proportioned and open, the ordinary atmospheric pressure will carry on the ventilation quite efficiently, and the whole hospital will be kept fresh and comfortable by the natural forces alone. There is no fear that the speed will not be enough to keep up efficient ventilation—it is more likely to be too great ; but there need be no fear of its being too great, because it is completely under control, and can be regulated to any rate desired by the valves at the ward inlets and outlets. ”

“ My experience is that a natural system of ventilation is, in the long run, the most reliable and satisfactory, provided, of course, that properly constructed ventilators are employed, and that they are skilfully applied by a competent engineer. ”

“ For instance, if comment be made to those in charge as to the closeness of schoolroom or ward, no such confusion of ideas should exist as to cause the temperature to be quoted in proof of the satisfactory condition of the air. So long as but one person in charge of a part of any building thus ventilated, fails to recognise that the thermometer registers temperature, but does not gauge atmospheric impurities, so long will an element of possible danger to health exist for those dependent on this and kindred means of air purification. ”

“ There are many different contrivances in use for washing, screening, and purifying the air, the majority of which answer their purpose fairly well, though the evidence would seem to indicate that they are found to be most effective when employed in conjunction with a ' natural ' system of ventilation where the air is not mechanically propelled, but is drawn through by extraction, the air being more thoroughly purified moving in at a low velocity than when forced in under pressure. ”

“ It is well known to sanitarians that such a mode of changing the air (downward ventilation) is inimical to health, being not only a direct cause, but a fruitful means of dissemination of disease, as evidenced by the report issued by the Local Government Board, one town, where the schools are mechanically ventilated on the down draught principle, being specially mentioned as the 'chief focus' of the disease (influenza) in Scotland."—Local Government Journal on Report to Parliament by the Local Government Board." ”

“ With natural ventilation by diffusion and extraction the evils described cannot occur, as the air is admitted at a level, and in a manner in accordance with the laws of Nature, the hot vitiated air being drawn off at the top of the building, to where it ascends, and not permitted to return, as with downward ventilation, to spread disease and death amongst those compelled to breathe it. ”

“ The really important point to be kept in view in regard to ventilation is, that before any system depending upon mechanical contrivances can be pronounced worthy of adoption, it must be demonstrated beyond dispute that it is not only as good as ordinary methods, but appreciably better. ”

“ The reputation of natural ventilation has suffered a good deal from the abortive attempts of individuals having little or no acquaintance with either the science or the practice of ventilation, and by the employment of so-called ventilating apparatus of crude and unscientific construction. The selection of ventilators is likewise sometimes left by an architect to the contractor, who naturally supplies those upon which he gets the largest profit, without troubling himself about their efficiency. ”

“ Engine-driving columns of air through a building is not ventilating it. . . . It is wholly misleading to take the registered volumes of air forced into or out of a building at certain points as in any way indicating how often in a given time the whole of the air is changed."—Building News.
Note.—When a volume of air is forced in under pressure a certain portion is deflected and descends, as with the downward system, returning the respired air to be reinhaled, also the products of combustion.'
Air Analysis and Defective Ventilation. ”

“ With the many diverse methods of ventilation which are at present in use there can be no fixed standard for determining the volume of air necessary to secure effective ventilation ; one system ensuring with a given volume a healthy atmosphere, to secure which with another system several times that volume may be required. ”

“ Science proves that there is not a moment of time but when there is a movement of the air, and that this movement properly utilised is sufficient at all times to change the air in a building and secure ventilation."—Houghton. ”

“ Natural ventilation is certainly much to be preferred to any and every artificial system, whether on the ' Plenum ' or vacuum principle, and it is, of course, much less complicated. It is, indeed, comparative simplicity itself—merely arranging openings and warming the air, and, as shown above, it acts more than efficiently. ”

“ It is a curious fact, and one that should be carefully noted, that not one single instance is given of the mechanical system having been tested against any automatic system, the schools mechanically ventilated being tested against schools having only the windows and doors to rely upon for ventilation—that is to say, schools in which no system of ventilation existed at all. It would have been interesting to have known what the results would have been had a good automatic system been in use, applied under equally skilled advice as the mechanical. ”

“ For the ventilation of rooms exits should be provided for the spent air near the ceiling. . . The method of low ventilation (extraction near the floor) should be avoided on various grounds."—Royal Commission on Ventilation (Blue Book) .
" The down system can never supply really pure air to be breathed by the lungs. The exhalations of the human body are, as they issue, so warm that they must perforce immediately rise. ”

“ For winter, and for spring and autumn, the outer air in our climate is generally too cold to be admitted through open windows. It is, of course, impossible to warm the air as it enters, before it impinges on the patients, when it is let in through open windows and the warming is done by open fires, because the patients lie between its entrance and the means of warming.
" Letting the air in through the windows tends to drive the air of the wards into the hospital, which is always objectionable ; and is also risky when there is infectious disease in the wards. ”

“ For hospital wards open fires are risky, costly, and troublesome ; they greatly embarrass all plans of ventilation, and are in many other ways objectionable. They are of but little use as means of ventilation ; they certainly abstract air, but they take it principally from near the floor, whereas the foul air accumulates near the ceiling, being heated and so made light by the same means that foul it. Hospitals warmed only by open fires are sure to be very imperfectly warmed ”

“ It is notorious that, in spite of elaborate tables or analysis of the air of many public buildings in which the most complete forms of artificial ventilation are in use, the condition of the air in these buildings is not found by those occupying them to be in accord with the analysis, so far as their sensations are concerned. ”

“ Louvre Board ventilators were originally designed for the purpose of preventing the weather from passing into a shaft. The large body of air which it admits at the top of the shaft, and which is supposed to pass across from one side to the other and thence out, simply acts as a damper upon the ascending current, and, in cold weather particularly passes down the shaft precipitating the vitiated air and causing a disagreeable downdraught."—Ventilation. ”

“ When a window is open at the top in cool weather, a stream of cold air passes into the room, spreads, and descends in a cold shower, cooling and pressing down the warm ascending vitiated air to be rebreathed, along with the poisonous products of combustion, and the dust and dirt with which the incoming air may be charged.
It is in cold weather that special ventilating arrangements, that will change the air without draught and at the same time purify it, are absolutely necessary. In warm weather, windows can safely be kept open, there being then not the same danger from draughts. ”

“ It is almost impossible in an ordinary room to make the smoke go down to the floor without a very violent effort. In all ordinary expulsion it would be noticed that the smoke ascends, and quickly becomes disseminated through the air of the room. The scientific fact is that air exhaled from the lungs is, at the moment of exhalation, equal in weight to pure air at a temperature of 90 deg. Fahr. And until the exhaled air has parted with so much of its heat as to become heavier than pure air at this temperature, it will rise in a normally pure atmosphere."—Builder (April 30th, 1898) . ”

“ The higher temperature in an occupied building—particularly in cold weather, when doors and windows are kept closed to exclude draughts—combined with the ascensional movement of the heated air arising from the lungs and body, are also utilised as powerful and never-failing auxiliaries in changing the air and inducing an inward and upward current, even when there is absolutely no perceptible movement of the air outside. ”

“ Where the initial outlay on hospital construction is so compulsorily a matter of supreme importance, it would seem advisable to secure very convincing proofs of the advantages derived from the mechanical ventilation in force at Glasgow and Birmingham, before incurring the cost of installing the ' Plenum ' system in other hospitals. It must be borne in mind that with an allowance of 1,000 cubic feet of air space per bed, adequate ventilation by natural means is practically always possible. ”

“ The latest evidence submitted at the Royal Institute of British Architects and at the International Congress of Hygiene, Budapest, has conclusively demonstrated that heated air employed for the double purpose of ventilation and warming is not only unhealthy, but fails as an efficient heating medium. ”

“ I am aware that some medical practitioners do recommend hospitals to be ventilated only by open windows on both sides of large wards, even in winter in this climate, and maintain that there is neither risk nor discomfort in doing so. They do not themselves, however, submit to such ventilation, that is, they do not themselves sit in their study, or have their families to sit in the morning room or sleep in bedrooms with windows to the east open all the winter through ! ”

“ When a building is ventilated with hot air, which also constitutes the means of heating, to satisfactorily effect the latter it is necessary to raise the air to such a high temperature that the oxygen is partially destroyed and its life-giving qualities considerably reduced. ”

“ In buildings, such as hospitals and asylums, an analysis of the air might be made periodically, as the medical superintendent would, in most cases, be qualified to judge if the tests were correctly made ; if he did not make them himself. In other buildings, such as churches, halls, schools, workrooms, &c., there would be some difficulty in securing reliable analysis, there being so many conditions under which tests may be made that might render them misleading, and valueless as indicating the general purity of the air. ”

“ Experience, and a more enlightened knowledge of the subject, have, however, taught us that with the more perfect forms of ventilation by extraction from the upper parts of a building, to where the warm expired air naturally ascends, considerably less than the least of these estimates is sufficient for all ordinary requirements. ”

“ Perfect ventilation would not be obtained, for this would only provide for the dilution of the impure air, while in perfect ventilation the impurities are not so diluted, but completely removed as fast as formed, so that no man can inspire any air which has shortly before been in his own lungs or in those of his neighbour. ”

“ At a time when the science of ventilation, and the natural laws which govern it, were but imperfectly understood, it was held by many, and still is by some, that a very large volume of air was necessary to dilute the vitiated air in a building to a healthy standard, from 2,000 to 6,000 cubic feet per hour per person being recommended. ”