An instrument for directing a current of air against burning fuel, to increase the combustion. The ordinary bellows, for domestic use, are so well known, as scarcely to require description, consisting merely of two flat boards, united by a sort of hinge joint, and having a piece of leather, (broad in the middle, and narrow at the two ends,) nailed round the sides of the boards, to allow them to separate or move through a small angle. In the lower board is a hole, through which the air enters, upon raising the upper board; but being prevented from escaping on pressing down the upper, by a leather flap valve, which covers the hole, it is forced through a pipe or nozzle fitted at the junction of the boards, and having a small valve behind it, opening outwards. For bellows for manufacturing purposes, see Blowing Machines.