HYDRAULICS. 193 



to 'the lower F. The rod of the piston B, is 

 carried through the piston, or bucket C. This 

 pump is very simple in its principle, and may be 

 executed at little expence. 



The pump invented by M. de la Hire raises 

 water equally quick by the descent, as by the 

 nscent, of the piston in the pump-barrel. 



A A (Fig. 70' * s a well* in which the lower ends 

 of the pipes B and C are placed. D is the pump- 

 barrel, into the lowermost end of which the top of 

 the open pipe B is soldered, and in the uppermost 

 end the hollow pipe S is soldered, which opens into 

 the barrel; and the top of the pipe C is soldered 

 into that piece. Each of these pipes has a valve on 

 its top, and so have the crooked pipes E and F, 

 whose lower ends are open into the pump-barrel, 

 and their upper ends into the box G. L is the 

 piston-rod, which moves up and down through a 

 collar of leather in the neck M; K is a solid 

 plunger, fastened to the rod or spear L: the 

 plunger never goes higher than K, nor lower than 

 D; so that from K to D is the length of the 

 stroke. 



As the plunger rises from D to K, the atmo- 

 sphere (pressing on the surface of the water A A 

 in the well) forces the water up the pipe B, through 

 the valve b> and fills the pump-barrel with water 

 up to the plunger; and during this time, the valves 

 e and S lie close and air-tight on the tops of the 

 pipes E and C. 



When the plunger is up to its greatest height, 

 at K, it stops there for an instant, and in that 

 instant the valve b falls, and stops the pipe B at 

 top. Then, as the plunger goes down, it cannot 

 force the water between K and D back through 



vol. i. o 



