Page:Popular Science Monthly Volume 23.djvu/638

620 of temperature of the air when leaving the heating-chamber and when re-entering the heating-chamber.

By this system there are about fifty-five thousand cubic feet of the interior of the house heated by radiation, through about thirty-five

 A, heating-chamber; B, openings in heating-chamber communicating with flues in the interior walls leading to spaces under the floors. The arrows show the direction taken by the current of air.

hundred square feet of floor and wall surfaces, and the capacity of the heating-chamber is fourteen hundred cubic feet, so there is one cubic foot of heated air to forty cubic feet in the house.

The temperature of the air in the heating-chamber averages, in very cold weather, 170°, and after delivering its surplus heat to the floors and interior walls, its temperature registers 58° in the flue where it re-enters the heating-chamber for reheating, showing that 112° of heat had been given up and utilized for warming purposes. With ordinary care in managing the furnace, a temperature of 68° can be uniformly maintained on the first floor, and from 60° to 62°