a machine so contrived as to expire and inspire the air by turns, by enlarging and contracting its capacity.

This machine is used in chambers and kitchens; in forges, furnaces, and founderies, to blow up the fire: It serves also for organs and other pneumatic instruments. ments, to give them a proper degree of air: All these are of various constructions, according to their different purposes; but in general they are composed of two flat boards, sometimes of an oval, sometimes of a triangular figure: Two or more hoops, bent according to the figure of the boards, are placed between them; a piece of leather, broad in the middle, and narrow at both ends, is nailed on the edges of the boards, which it thus unites together; as also on the hoops which separate the boards, that the leather may the easier open and fold again; a tube of iron, brass, or copper is fastened to the undermost board, and there is a valve within that covers the holes in the under-board to keep in the air.

Each pair of bellows imported is valued in the book of rates at three shillings and four pence, and pays duty \( \frac{7}{10} \) d., whereof \( \frac{6}{10} \) d. is drawn back on exportation. See Pneumatics.