Theory of the Bellows. 89 



A represents a strong and firm box, Covipressi o7i BeUows. 



four feet square, two of whose sides, 

 a, b, are a foot deep each ; and its 

 other two sides c, d, two feet deep at 

 their center, and from thence taper- 

 ing down, even with the sides a, b. 

 L, M represent the bottom of this 

 box, which is fastened air tight to the 

 tapering sides c, d, and the others a, b. This box, when construct- 

 ed, will resemble an inverted roof with a small portion of the sides of 

 the building attached thereto, and its bottom the ridge. In the two 

 sides of the bottom L, M, are to be inserted two valves n, r, one in 

 each, four inches by eight, which are to open upwards into this box, 

 from ten to twenty degrees. These valves n, r, must be hung as 

 near to the sides a, b, as they conveniently can. o, o, represent the 

 sides of the valves n, r, hung to the bottom. A strong cover is now to 

 be made that will exactly cover over the top of this box, or even more ; 

 and we must provide a strong strip of leather or some other very 

 strong and flexible substance impervious to the air, four feet wide and 

 nearly seventeen long, with its ends tightly sewed together, which is 

 to be fastened air tight, first around the tops of the sides a,b, c, d of 

 the box A, and then around the sides of the cover. This will form 

 the cistern into which the air is to be compressed or condensed, 

 and from which it can be let out in any direction required, or with 

 any velocity. Immediately under this cistern and directly under the 

 valves n, r in its bottom, a strong board, one foot wide and four long, 

 is to be exactly balanced across its ridge and hung by means of sta- 

 ples, hinges, or otherwise, so as to move easily upwards and down- 

 wards, and without wavering. On one end of this board, a handle 

 to move it is to be attached, which can be of any length required. 

 Holes are to be cut for valves, through each end of this board, of 

 nearly the same size of those in the box A, and so as to be directly 

 under them. Valves are to be hung over these holes so as to open 

 and move just the same as those in the bottom of the box A. This 

 being done, the sides of this board and the box A, are to be connect- 

 ed by some impervious and strong substance, such as leather, fitted on 

 air tight, and so as to allow the balancing motion of the board. The 

 box A or air cistern being now, in some way or other, made fast, so as 

 to allow the free balancing of this board, all is ready for operation. 

 The handle attached to the balancing board, being now moved or 



Vol. XXVII.— No. 1. 12 



