90 Theory of the Bellows. 



raised and depressed powerfully, it will open and shut the valves, al- 

 ternately, on each side of the ridge ofthe botlom of the box A, and con- 

 sequently alternate partial vacuums will be formed, into which the ad- 

 jacent air will rush, and from which it will be forced into the air cis- 

 tern, where it can be compressed to any degree. When the handle 

 which is attached to one extremity of this valved and balancing board 

 is raised, the valve between it and the ridge closes light and forces all 

 the air inside between the valves into the air cistern, through the 

 valve over, which likewise opens upwards ; while on the opposite 

 side of the ridge, the valve in the air cistern closes tight to hold what 

 air is in ; and the valve below it opens to let air between the valves, 

 which will be forced into the cistern, when the handle is brought 

 down. The cistern of this compression bellows, especially if very 

 large, instead of being filled full by the sole motion of this balancing 

 board, may be nearly immediately filled, by having a staple clench- 

 ed through the middle of its cover, and a rope attached to that, and 

 then run over a fixed pulley, so that as fast as the cover is raised by 

 pulling the rope, the cistern will fill, as all the valves will open up 

 merely by the pressure of the atmosphere ; and when it is thus filled, 

 the balancing board can be moved so as to give the air drawn in, 

 any pressure. Instead of having the bottom of the cistern roofed or 

 ridged for the purpose of balancing the board across, it can be flat, 

 and then the board must be bent at the balancing point, each way 

 downward, or being hung immediately by its middle to the bottom of 

 the cistern, its extremities must be gradually and sufficiently inclined 

 to allow the balancing motion required, in order to force the gathered 

 air into the cistern above. The width and even length of this bal- 

 ancing board can be varied to answer the dimensions and construc- 

 tion of any cistern. The dimensions, shape and construction of 

 bellows made on this principle of a balance are susceptible of a great 

 variety of different modifications ; those that I have given were for 

 the purpose of easier illustration, not the best operation, as this can 

 be determined only by extensive experiments. With regard to the 

 operation of bellows on this principle, it is evident from reason and 

 the extent of my experiments, that it will be easy, steady, and regu- 

 lar, and susceptible of powerful exertion. Where a constant and 

 very powerful blast is required, as in great furnaces and for casting 

 and hammering, it will probably answer better than in common shops. 

 On this principle there will be no loss of motion, and whether the 

 handle is moved upwards or downwards, it will force the same quan- 



