PUMP. 



the pipe remains. Un again raising 

 the piston, the same eflect is repeat- 

 ed, and an additional ijiiantity of wa- 

 ter enters the pipe, 'i'hii.s, by the al- 

 ternating motion of the piston, a col- 

 umn of water is raised in the pipe 

 until it reaches the piston when at 

 the bottom of ttie barrel, and the 

 whole of the air below it has been 

 excluded. On raising the piston 

 when the water has reached it, the 

 fluid will be compelled to follow by 

 the pressure of the atmosphere on its 

 surface in the well. Wlien the pis- 

 ton is again depressed, Uie water 

 flows through the valve in it, and as- 

 cends into the barrel, and by the suc- 

 ceeding strokes of the piston is lifted 

 up until it reaches and flows out of 

 the spout, F. 



" Although in theory the limit of 

 the height to which water may be 

 raised by the sucking pump, from the 

 surface of the fluid in the well to the 

 highest position of the moveable pis- 

 ton, is about thirty-four feet (the 

 height of a column of water which 

 balances the pressure of the atmo- 

 sphere), it is not found practicable, 

 with pumpo of the ordinary construc- 

 tion, to raise it more than about twen- 

 ty-eight feet. The difference arises 

 from the difficulty of making the ap- 

 paratus absolutely air-tight. 



" The forcing pump is represented 

 in Fig. a. The piston-rod, E D, is 



Fig. 3. 



Fig. 2. 



attached to a solid 

 plunger, D, adjusted to 

 the cavity of the bar- 

 rel. A pipe, G H, fur- 

 nished with a valve, 

 F, opening outward, 

 communicates with 

 the barrel at G. On el- 

 evating the plunger, D, 

 the water will ascend 

 through the valve, C, 

 in the same manner as 

 in the sucking pump, 

 till the barrel is filled to D. Now when 

 the plunger is depressed, the valve, 

 C, will shut, and the water between 

 D and C be forced through the valve 

 F into the pipe G H. When the 

 plunger is raised, the valve at F shuts, 

 the pressure on its under side being 

 646 



removed, so that the water which 

 was forced into the pipe l)y the pre- 

 vious stroke cannot return into the 

 barrel. At the next stroke of the 

 piston more water is again forced 

 into the pipe, and so on till it is rais- 

 ed to the height reijuired. 



" In this pump the pipe, A A, may 

 be dispensed with, and the barrel, B, 

 immersed in the reservoir ; in which 

 case the action of the pump is inde- 

 pendent of the atmospheric pressure, 

 and could be maintained equally well 

 in a vacuum. 



" In order to produce a continued 

 stream through the pipe, G H, an air 

 vessel, 7)1 7), may be 

 attached to the lateral 

 branch above the valve 

 F, Fig. 3. The pipe, 

 G H, reaches to i>ear 

 the bottom of the air- 

 vessel ; and when the 

 water has been forced 

 into the vessel by the 

 action of the pump, un- 

 til it reaches above the 

 lower end of the pipe at G. it is evi- 

 dent that, as all communication is 

 then cut ofTwilh the external atmo- 

 sphere, every additional quantity of 

 water thrown into the vessel will tend 

 more and more to compress the air 

 within it, which, acting by its press- 

 ure on the surface of the water, for- 

 ces it through the pipe, G H, in a con- 

 tinued stream. 



" The lifting pvmp is represented 

 by Fig. 4. The barrel of the pump 

 is immersed in the water 

 and fixed to an immovea- 

 ble frame. The piston, 

 with its bucket and valve, 

 C, opening upward, is at- 

 tached at E to another 

 frame, G H I K L, consist- 

 ingof twostrongiron rods, 

 H I and L K, wliich move 

 through holes in frame- 

 work to which the pump 

 is fixed. An inclined 

 branch, M N, either fixed to the top 

 of the barrel, or moveable by means 

 of a ball and socket, is fitted exactly 

 to the barrel, and furnished with a 

 valve at M. Suppose the barrel im- 



