72 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK i. 



the manner in which the water acted in three vertical tubes furnished 



FIG. 46. Hydraulic ram for compressing air. Theoretical diayran 



i 



Fici. 47. Double-action compression pump, Fryer's system (New York). 



with valves for forcing the air into the receiver, were used. The water 



