In arranging for pure air in dwellings, it is needful to proportion the air admitted and discharged to the number of persons. As a guide to this, we have the following calculation: On an average, every adult vitiates about half a pint of air at each inspiration, and inspires twenty times a minute. This would amount to one hogshead of air vitiated every hour by every grown person. To keep the air pure, this amount should enter and be carried out every hour for each person. If, then, ten persons assemble in a dining-room, ten hogsheads of air should enter and ten be discharged each hour. By the same rule, a gathering of five hundred persons demands the entrance and discharge of five hundred hogsheads of air every hour, and a thousand persons require a thousand hogsheads of air every hour.
In calculating the size of registers and conductors, then, we must have reference to the number of persons who are to abide in a dwelling; while for rooms or halls intended for large gatherings, a far greater allowance must be made.
The most successful mode before the public, both for warming and ventilation, is that of Lewis Leeds, who was employed by government to ventilate the military hospitals and also the treasury building at Washington. This method has been adopted in various school-houses, and also by A. T. Stewart in his hotel for women in New-York City. The Leeds plan embraces the mode of heating both by radiation and convection, very much resembling the open fireplace in operation, and yet securing great economy. It is modeled strictly after the mode adopted by the Creator in warming and ventilating the earth, the home of his great earthly family. It aims to have a passage of pure air through, every room, as the breezes pass over the hills, and to have a method of warming chiefly by radiation, as the earth is warmed by the sun. In addition to this, the air is to be provided with moisture, as it is supplied out-doors by exhalations from the earth, and its trees and plants.
The mode of accomplishing this is by placing coils of steam, or hot water pipes, under windows, which warm the parlor walls and furniture, partly by radiation, and partly by the air warmed on the heated surfaces of the coils. At the same time, by regulating registers, or by simply opening the lower part of the window, the pure air, guarded from immediate entrance into the room, is admitted directly upon the coils, so that it is partially warmed before it reaches the person: and thus cold drafts are prevented. Then the vitiated air is drawn off through registers both at the top and bottom of the room, opening into a heated exhausting flue, through which the constantly ascending current of warm air carries it off. These heated coils are often used for warming houses without any arrangement for carrying off the vitiated air, when, of course, their peculiar usefulness is gone.
The moisture may be supplied by a broad vessel placed on or close to the heated coils, giving a large surface for evaporation. When rooms are warmed chiefly by radiated heat, the air can be borne much cooler than in rooms warmed by hot-air furnaces, just as a person in the radiating sun can bear much cooler air than in the shade. A time will come when walls and floors will be contrived to radiate heat instead of absorbing it from the occupants of houses, as is generally the case at the present time, and then all can breathe pure and cool air.
We are now prepared to examine more in detail the modes of warming and ventilation employed in the dwellings planned for this work.
In doing this, it should be remembered that the aim is not to give plans of houses to suit the architectural taste or the domestic convenience of persons who intend to keep several servants, and care little whether they breathe pure or bad air, nor of persons who do not wish to educate their children to manual industry or to habits of close economy.
On the contrary, the aim is, first, to secure a house in which every room shall be perfectly ventilated both day and night, and that too without the watchful care and constant attention and intelligence needful in houses not provided with a proper and successful mode of ventilation.
The next aim is, to arrange the conveniences of domestic labor so as to save time, and also to render such work less repulsive than it is made by common methods, so that children can be trained to love house-work. And lastly, economy of expense in house-building is sought. These things should be borne in mind in examining the plans of this work.
In the Cottage plan, (Chap II. Fig. 1,) the pure air for rooms on the ground floor is to be introduced by a wooden conductor one foot square, running under the floor from the front door to the stove-room; with cross branches to the two large rooms. The pure air passes through this, protected outside by wire netting, and delivered inside through registers in each room, as indicated in Fig. 1.