[Copied from How To Do Things, published in 1919 by the Wilmer Atkinson Company, Philadelphia, PA.]
The cut shows an arrangement that exactly reverses the operation of a refrigerator. The pan of dough is placed at the top of the space instead of the ice, and the hot water jug is put at the bottom where the food would be placed in a refrigerator. The heat rises all night long from the jug and surrounds the pan of dough. The box should be perfectly tight, woolen strips being used for the door to shut against [with a hook and eye or other latch securing the door]. In very cold weather a blanket can be thrown over the box at night.