Page:Popular Science Monthly Volume 41.djvu/853





 Section A-B, showing inlet of air into the basement passage where the air is warmed. G L, the ground level of the garden. C L, the ground level of the basement or cellar. GR. F., the parlor floor, or first floor of the house. The inlet of air as indicated by the arrows is below the smoke-flue, which is suspended in the center of the passage, so as to warm the air in this passage. Section C-D. G. R. shows the outlet of the air above the smoke-flue. The air warmed by contact with this flue passes upward in the intervening space between the inner and outer walls of the house, so as to warm the entire substance of the walls.

contraction of the iron with which it is made. The drawing C D shows how the air warmed in this passage ascends into the space between the two walls of the house. There are a number of these openings into the hollow of the wall all round the house.

The temperature in the hot-air passage varies from 114° to 122° Fahr. This suffices to bring up the temperature of the inner wall on the ground-floor from 86° to 92° Fahr. The temperature of the inner wall decreases by about one degree centigrade per metre of height. Thus, if the wall on the ground-floor level is at 35°, it will be 32° C. on the level of the first floor, which is three metres higher up. The hot air that travels up the hollow of the walls comes out in the large attic under the roof of the house. If this air is warmed to from 114° to 122° Fahr. when it enters the space between the walls it will have fallen to about 104° Fahr. as it emerges from the wall into the attic. From this attic the hot air filters into the open through the porosity of the roof and by the various openings, chinks, etc.

Much of the success of this experiment depends upon the porosity of the walls. Every precaution is taken not to interfere with this porosity. There is no plaster-work put on the walls, and there is no paint or paper. A light wooden frame is nailed on to the walls, and from this tapestry—that is, a tissue, as far as possible a woolen tissue—is suspended and replaces paper. Some hangings of this description can be obtained that are hardly any dearer than good paper, and though for artistic purposes expensive woolens are employed, the expense in the long run is not great, for the cloth lasts an indefinite time, and, unlike paper, can be taken down and cleaned. It also contributes very materially