The Self-Regulating Ventilator.

Explanation:—This is a cheap and simple but scientific apparatus for regulating the air-vent of a common, cheap stove, according to the temperature of the atmosphere in the room in which it is located. The draught door is a plain iron door, hung by a common hinge joint at the upper end; and to the front of the hinge is attached a piece of brass wire, which extends vertically nearly to the top of the room, and is connected at B to a horizontal brass wire C D. This is the only apparatus required, but must be so adjusted as to allow the door to be closed, or nearly so, when the temperature is about right. If the temperature rises above that point, the horizontal wire will immediately expand so as to allow the door to close. But as soon as the temperature begins to fail, the wire contracts and opens the vent. On this principle the apparatus will readily find a medium, and there remain, varying only occasionally to accommodate itself to the variations of the quantity of fuel in the stove. The entire expense of this apparatus, exclusive of the stove, will not exceed 50 cents. It is generally conceded that a large portion of cases of colds, coughs, &c. are occasioned by irregularities of the temperature of sitting-rooms but with this plan of regulation this evil may be avoided without any material expense.