HYDROSTATICS. 



121 



FIG. 71. 



strong reservoir and a piston, working water-tight, are 

 used. The substance to be pressed is placed between K, 

 the head of the piston, and an immovable plate MN. The 

 reservoir and the cylinder of the pump are connected 

 by the tube d. By the action of the pump, the water in 

 the cylinder A is subjected to pressure, and this pressure 

 is transmitted undiminished to the water in B. According 

 to the law given in 219, the power exerted upon the 

 lower surfaces of the two pistons is proportional to their 

 respective areas. But the force exerted by the water upon 

 the under surface of the piston in the pump is the same as 

 the force exerted upon the water by that piston, (equality 

 of action and reaction). The piston a is generally worked 

 by a lever of the second class, resulting in a still further 

 gain of intensity of power. If the power arm of the lever 

 be ten times as long as the weight-arm, a power of 50 Kg. 

 at the end of the lever will exert a pressure of 500 Kg. 

 upon the water in A. If the piston in A have a sectional 

 area of 1 sq, cm. and the piston in B have an area of 500 

 6 



