2 



IVtu^Cs Patent for Improvernents 



power required for opening and shutting the valves is 

 supplied by gearing, or mechanical movements, from the 

 engine, or other source of power by which the air-pump 

 is actuated, so that the inlet valves are opened and shut 

 alternately, almost immediately after the commencement 

 of the stroke of the piston of the pump, and the outlet 

 valves are respectively closed, or pushed home, at the end 

 or conclusion of the stroke of the piston. The gearing 

 afterwards releases the valve, which is retained on its seat 

 by the pressure of the external air, until the air within 

 the cylinder of the pump becomes nearly of the same 

 density as the external air, when the valve (if the lower 

 outlet) falls by its own weight, or (if the upper outlet) is 

 raised by a counterpoise of greater weight than the valve, 

 or by a spring, thus moving rather in advance, or as 

 though in anticipation of the current of expelled air, and 

 affording a free passage for it. 



And, in order that this part of my invention may be 

 fully understood, I refer to the annexed drawing or sheet, 

 No. 1, though many different modifications of apparatus 

 and machinery may be used to effect the like purpose, in 

 which drawing, a, a, represents the cylinder of the pump, 

 B, the piston, c, the piston-rod, d, d, d, pipes communi- 

 cating between the main, or vessel to be exhausted, and 

 the upper inlet valve-box, e, and the lower inlet valve-box, 

 F. G, represents the upper inlet valve, and h, the lower 

 inlet valve, which valves, g, and h, are attached to the 

 rods, I, and i, at v, and v, by joints, allowing a slight 

 motion, so that the valves may the better close on their 

 respective seats. The rods, i, and i, move air tight, in 

 stuffing-boxes, k, and k, and are moved, or worked, in 

 suitable guides, by levers, l, l, furnished with suitable 

 joints, and connected by the rod, t, t, part of which only 

 is shown, with a suitable eccentric movement, but for 

 which I prefer one of the eccentrics hereinafter more 

 particularly described or mentioned, but which is not 

 shown on the drawing now referred to. m, represents 

 the upper outlet valve, and n, the lower outlet valve, 

 respectively attached to the rods, o, and o, moving in 

 suitable guides, and which valves, m, and n, may be 

 respectively closed by the levers, p, and p, suitably fixed 

 and acting upon the studs or tappets, q, and q, so as to 

 close the valves, m, and n, alternately, but not to open 

 them. The upper valve, m, is counterpoised, and some- 



