Page:Popular Science Monthly Volume 29.djvu/253

Rh be found—such as an angle of 60°—but commencing a few inches above the fire so as not to lower the angle B where the lean-over returns to the chimney.



"The shape of the grate should be based upon a square described within an equilateral triangle, the size to vary in constant proportion to the side of the square" (Fig. 2).—The shape of the grate, or grid, is arrived at in the following way: Describe a square, D, of which the sides shall be eight, nine, or ten inches, according to the size of the room, within an equilateral triangle, E, the two sides of which