248
[Book III.
“ A, B, C, D, is a box divided into two chambers at the line 0 H. Inthe upper one is tbe piston E, which is moved backwards and forwardsby means of tbe handles attached to it; and is made to fit closely by
means of leatber or paper.Tbe lid of the box slidesupon tbe top, and is suffi-ciently thick to allow the
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At F J are two smallholes eaoh covered with avalve ; and just belowtbem, at O H in the divi-sion of the two chambers, are larger holes, for the entrance of thewind into the lower chamber. This part of the bellows is made of athick plank, hollowed into an ovoid form, and is about an inch thick.The clapper G is fastened to the back side of the box, and plays hori-zontally against the two stops placed near the mouth I. It is made ashigh as the chamber, and when forced against the stop, it entirely closesthe passage of air beyond. When the piston is forced inwards, as repre-sented in the cut, the valve at F is closed, and that at J is opened; andthus the upper chamber is constantly filled with air. The wind driveninto the lower chamber by the piston urges the clapper G against thestop, and is consequently forced out at the mouth. The stream of air is unin-terrupted, but not equable, though in the large ones the inequality ishardlyperceived. An iron tube is sometimes attached to the mouth which leadsto the furnace, and in other cases the mouth itself is made of iron.” TheChinese generally use them in an inclined or horizontal position, frequentlymaking use of the upper side as a work bench. In the figure (and theone given by Chambers) two rods are connected to the piston to preventit from springing when used : this appears to be the practice with regardto those of large dimensions. In small ones a single rod is sometimes used,and the chamber is cylindrical. In the Collection of M. Bertin, (a French minister and secretary of state in the former part of the last Century,)which contained “ about 400 original drawings, made at Pekin, of thearts and manufactures of China ” a portable and single-acting bellows isrepresented as in the next figure. a
No. 113. Chinese Single Bellows, and Tinker.the airis forced out by the opposite extremity.”
“ This instrument ismade like a box inwhich is a piston, soconstructed that whenit is drawn out behind,the vacuum which it oc-casions in the box makesthe air rush in with greatimpetuosity through alateral opening, to whicha sucker [a valve] is af-fixed: and when the pis-ton returns in an inversedirection, the sucker[valve] closes itself, andNavarette preferred the