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action of which his system depended, until the House had sat for some time, and the chamber had got thoroughly heated, so that we cannot wonder some of the members should have considered the design of cooling the House was frustrated, and requested the doctor to employ other means. He accordingly invented a centrifugal wheel, or blowing machine, so constructed as to force air either into or out of the House, according as either was required. This machine was put in charge of a man called the ventilator, whose duty it was to wait upon Mr. Speaker every day for orders, Dr. Desaguliers was next applied to by the Admiralty to ventilate ships, but here, as might be expected, he got inventors’ allowance, viz., more kicks than halfpence. All his troubles with Mrs. Smith were nothing compared with the treatment he and his invention received from Sir Jacob Ackworth, the Surveyor to the Navy, who seems to have been the beau ideal of an official. When the doctor attended by appointment on board the ship in which his machine was to be tried, Sir Jacob did not appear, but hearing that the company were pleased afterwards told Dr. Desaguliers that at the next experiment he (the doctor) need not attend, as the carpenter could manage the ventilation. When the second trial came off, Sir Jacob had scuttle holes cut at each end of the ship and then hoisted enormous windsails, and when, as might maturally be expected, he found that more air came through his windsails, which were about 2'. 6" diameter than through the Doctor's tubes, which were 5" x 3'; he said he could not stay longer, and that he was sorry the machine had answered no better. Sir Jacob, however, sent his “humble duty” to Dr. Desaguliers, and thought his invention might be a very pretty thing in a house. The Lords of the Admiralty never came near nor gave themselves any trouble about it, and so the Doctor found his invention would not be used in the Navy. The next person who came forward in the cause of ventilation for the Navy, was Mr. Sutton, a brewer by trade. He made use of the fire which cooked the provisions of the ship's company as the motive power, laying pipes from all parts of the ship to the ashpit under the grate. When the ashpit-door was closed, no air could get to the fire except through the pipes. The result was considered satisfactory, and the apparatus was ordered to be fitted up on board the “Norwich’’ man-ofWar. Mr. Sutton had also to contend with Sir Jacob Ackworth, but he had found powerful friends in Dr. Mead, the King's Physician, and Sir Charles Wager, so that the old knight's opposition was rather passive than active.

This, I believe, is one of the first, if not the first, instance of the scientific use of the common fire as the power for ventilating any structure. This method has been called thermo-ventilation by Mr. Bernan, to whose work, as well as to those of the inventors, whose names I havementioned, I am indebted for many of the particulars given above. However successful Mr. Sutton may have been in getting his apparatus fixed, he failed when he applied to the Admiralty for some reward for his services, they simply took no notice of him or his petition, although the “Norwich * had returned to England from the Guinea Coast, with the loss of only two men, and the Captain reported her singularly healthy. Meanwhile, a certain Dr. Hales had been pressing an invention of his own upon the notice of my Lords. This he called a ship's lungs. The machine was, in fact, a magnified bellows, differing somewhat in construction from common bellows certainly, but the same as far as action was concerned. It consisted of a large square case with valves, enclosing a hinged midrif, which rose and fell by the action of a long handle or lever, worked by some of the ship's company. The whole machine was cumbersome, requiring about four men per hour to work it, and could not, certainly, compare with the blowingwheel of Dr. Deraguliers. It soon fell into disuse, and became a thing of the past. Mr. Sutton, who had at last got £100 from the Admiralty, exulted over the failure of the ship lungs, but his triumph was short lived, for, in the course of a few years, he found that he was left out in the cold also, and the old wind-sails were again on duty. The illustrious names of Count Rumford and Sir H. Davy, as well as those of a host of other persons less celebrated, which figure in the annals of ventilation, attest the importance of the question. It is time, however, for me to take leave of this portion of my subject, of which volumes might be written, and to consider the causes which make ventilation a necessity. These may be classed under different heads, viz.: 1st in private houses. The necessity for ventilation will arise from commonly (A) the presence of fires; (B) artificial light ; (c) the presence of persons living in the house, that is from the air required by them, as well as the exhalations from their bodies, and (D) from badly constructed waterclosets, cesspools and drains. 2nd. In factories there will be, in addition to the above causes, the presence in the air of a vast quantity of minutely-divided fibre and dust, which is highly prejudicial to the health of the workers, and also the fumes from chemicals, &c., where the manufacture of such is carried on. (3rd.) In sewers. The necessity of sufficient ventilation will almost entirely arise from the generation of poisonous gases by the putrid filth carried down. (4th.) And in underground railways, the fires of the engines, and the Saturation of air by the waste steam will render ventilation, in certain cases, necessary. Considering these cases in the above order, we have 1st, in dwelling houses (A), the presence of fires. At first sight it would seem an error to include this under the head of causes which make ventilation necessary. . As fires are often, indeed mostly, the only means of ventilation in private houses. But under the term I include not only the removal of foul air, but the supply of fresh, and from this point of view it will be seen that the common fire is a very great consumer of fresh air, and requires a supply of that quite as much as of the fuel which feeds it. It may be as well to mention here some of the well-known facts connected with the combustion of fuel. The fuels commonly used are composed, principally, of carbon and hydrogen in about the following proportions:—

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Now, combustion consists in the union of oxygen gas with the elements carbon and hydrogen, and the result is a development of light and heat, and the formation of carbonic acid and water, the carbon of the fuel uniting with the oxygen of the air to form carbonic acid, and the hydrogen doing the same to form water.

Carbon exists in its pure and crystallized form as the diamond, and this beautiful gem is combustible in oxygen gas, burning entirely to carbonic acid. This experiment has been tried, however, only in the laboratory. o

One pound of carbon requires for its combustion 158 cubic feet of air, while the same weight of hydrogen requires 473 cubic feet. From these facts it will be seen that the different fuels mentioned above will take for their proper combustion the following minimum quantities of air, viz.:

Coal .............................. 148 cubic o
Coke ......... 134 2x

Wood ... ... 65 , per pound.
Charcoal 147 xx

Peat ...... - 81 11

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There is a certain quantity of oxygen in coal, wood, and peat, which somewhat reduces the amount of atmospheric air required by these fuels. From the above tables—for which I am indebted to the researches of Péclet, Playfair, Regnault, and others, and which, assume the temperature of the air to be 62°F.—it will be seen that the ordinary fire plays no unimportant part in the consumption of air; for, if we assume one pound of coal per hour as the quantity required, then 148 cubic feet of air will be consumed in that period, or 2.46 feet per minute, or 2,072 cubic feet per day of 14 hours. These, as I have said, are minimum quantities. In practice, at least double must be allowed, as a large per centage will escape unconsumed. In the case of the common fire, the products of combustion do not certainly escape into the room, but the air to supply the fire is required all the same, and I feel sure that not in one house in a hundred is this supply ever thought of, but is left to chance, and the cracks in the doors and windows from which drafts whistle across the room in every direction. The second cause (B)—artificial light—requires far more serious consideration than the fire, for, commonly, the products of combustion are passed directly into the room, and are breathed in a diluted form by the persons in it. The introduction of coal gas has been most permicious in this respect, for few houses are built with any regard to the method of lighting, nor are the ways in which the gas is generally burnt calculated for anything but to do the greatest amount of injury to the persons using it. Some forms of gas-light, such as the sun burners and the ventilating globe light, are comparatively free from defect in these respects, but I have never seen the latter used save in one or two private houses, and the former are almost entirely confined to offices and public buildings. I have experienced some difficulty in obtaining the quantity of air consumed by the ordinary bat's-wing or fish-tail burner when lighted. But taking the Argand burner using 5 feet of gas per hour, and 45 feet of common air in the same time, as a standard, and knowing that the common burners burn from 2 to 6 feet per hour, according to size and pressure, I think I shall be safe in calculating the average consumption of gas by the common burners at 4 cubic feet per hour, and the amount of air at 36 cubic feet per hour. Now a room 25 feet long by 16 feet broad, and 10' 6" high will contain 4,200 cubic feet of air, but a deduction must be made for furniture, &c., of at least 10 per cent, leaving 3,780 cubic feet, or say 3,800, as the met quantity of air in the room.

Such a room will require at least three gas burners to light it, and these, as we have seen, will consume 108 cubic feet of air per hour, rendering it absolutely unfit for breathing by depriving it of its necessary proportion of oxygen. Ordinary candles do not vitiate more than 11 cubic feet of air per hour, per candle. As the chief constituents of coal gas are carbon and hydrogen, so the principal results of its combustion are carbonic acid and water. This water, in the form of vapour saturates the air of the room, which has a greater capacity for moisture when warm than when cold. This may be readily seen if in a close warm room, we examine the windows where the moisture will be found condensed, and perhaps running down the glass in streams. The same effect will be produced by placing a glass bottle filled with cold water on the table, the moisture will settle thickly upon it like dew upon the grass on a clear night, The reason is this. The air cooled by contact with the cold glass is no longer able to sustain the moisture, and the latter is therefore precipitated in the form of dew. (c.) The third cause I have mentioned is the presence of living beings in the room. Let us now consider the effect of this. Man's body is a furnace, a slow combustion furnace if you will, but still a furnace, and the waste from this human furnace is precisely the same as that from any other furnace, viz.: carbonic acid and water. To quote the words of Professor Tyndall. “In the animal body the carbon and hydrogen of the vegetable are again brought into contact with the oxygen from which they had been divorced, and which is now supplied by the lungs. Re-union takes place, and animal heat is the result. Save as regards intensity, there is no difference between the combustion that goes on within us, and that of an ordinary fire.” We see then of what vital consequence is the presence of oxygen in the atmosphere. Without it fires and lights will not burn, our food will not digest, and the blood remains unpurified, as is shewn by the pale faces and purple lips of people living in close warm rooms. These are the forerunners of certain death to persons deprived of the life-sustaining oxygen. Atmospheric air consists of a mixture of several gases, for though it is commonly said to be formed of oxygen and nitrogen in proportion of 21 volumes of the former to 79 of the latter, in each 100, yet several other gases are mixed with these. The composition of air varies with its situation. Thus, inland air is not of precisely the same composition as that near the sea coast, where there is said to be a greater proportion of ozone.

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