252 Double acting Bellows of Madagascar . [Book III.
row on furnaces, having a separate opening under each of them for re-ceiving the fuel, which consisted of a few small sticks and straw. Onhis pulling a thong, he blew a pair of bellows which made all his kettlesboil in a very short time.” c Like other Asiatics, the Chinese have proba-bly a variety of these instruments. The van, or winnowing machine,which we have received from them, is a rotary bellows. See page 70of this volume.
Various rotary bellows are described by Agricola, as employed in theVentilation of mines, and worked by men with cranks, and in one instanceby a horse treading on the periphery of a wheel. d Rotary blowingmachines have been represented as of more recent origin, but they are inall probability of great antiquity. The Spaniards introduced them intoPeru as early as 1545, to reduce the silver ores, but they were soon aban-doned." For rotary pumps, see a subsequent chapter of this book.
We are indebted for some interesting Information respecting the arts ofvarious islanders of the Indian ocean to Mr. William Clark of Philadel-phia , who, besides spending several years in whaling voyages, residedtwo years in Southern Africa . The vessel to which he was attached hav-ing on one occasion touched on the coast of Madagascar , some nativesmiths were found using bellows that excited particular attention; somewere cylindrical, being formed of bored logs, others were square trunks,five or six inches in diameter, and about five feet long; but the internalconstruction of both was the same. The ship’s carpenter was permittedto open one. It was composed of four planks that had been split fromtrees, the insides shaved smooth and straight, and the whole put togetherwith wooden pins instead of nails or screws. It was divided into twoparts by a partition or disk, which was permanentiy secured in its place,(shown at A in the annexed cut,) where, like a piston, it occupied theentire space across. On one side of the trunk, andopposite the edge of A, an opening was made forthe insertion of the tube C that conveyed the windto the fire, the edge of A at this place being feather-ed, and a small projecting piece added to it, inOrder to direct the current of air from either sideof the partition into C. An opening was made inthe centre of A, through which a smooth pistonrod B, played ; two pistons or boards, P P, accu-rately fitted to work in the trunk, were attachedon opposite sides of the partition to B; these pis-tons were perforated, and the openings covered byflaps or valves like those of a common pump box,but the upper one was secured to the under sideof the piston as shown in the figure. The trunkrested on four short pieces of wood pegged to it.In some, holes were made at the lower part forthe admission of air. These bellows were there-fore double acting, and consequently one of themwas equal in its effects to two of those representedatNo. 111, which drive the air out only on the de-scent of the piston, whereas these forced it into thefire both on ascending and descending. Thus,when the blower raised the rod B, the flap on thelower piston closed, and the air in that division of
c Beils Travels, i. 312. d De Re Metallica, pp. 162, 163, 164, 169. e Garcilasso’sCommentanes, p. 347.
No. 114. Double Acting Bel-lows of Madagascar.