120 



ELEMENTS OF GENERAL SCIENCE 



inches in diameter, and possibly eight or ten inches in length. 

 At the bottom it is connected with the pipe, sometimes called 

 the suction pipe, which extends down into the water in the 

 well, and at the top with a pipe leading to the spout, or 

 the spout may be connected directly with the cylinder. At 



A 



B 



FIG. 64. The lift pump 



Three stages of the stroke of the pump are shown: A, down stroke; B, up 



stroke ; C, completion of the stroke. By noting the position in each case of v 



(the valve), p (the piston, or plunger), and cyl. (the cylinder), the action of the 



pump may be understood 



the bottom of the cylinder, over the opening leading to the 

 pipe, there is a valve which is so constructed as to allow the 

 water to pass upward but not downward. In the cylinder 

 there is a tightly fitting piston. This may slide up and down, 

 and in it there is another valve which allows the passage of 

 the water upward through the piston. Other parts, such as 



