"An economical method of heating two rooms by one ...[fireplace] is described by Savot. A plate of iron is made to separate the fire-places of the two adjacent rooms. A fire made on the hearth, a, (Fig. 20), heats the plate, n, and this, in its turn, by its radiation, warms the air in the adjacent room, e, as effectually as a stove would do, provided its flue, i, is properly closed. Or if the second room have no chimney, it may... be warmed by making an opening in the wall... and closing it with an iron plate. When Dr. Franklin was in Paris, he saw an example of this contrivance, and estimated it highly."