THE WATER-RAM. 201 



running ; therefore the valve, D, drops open again, and 

 permits it to escape. It recommences running, until 

 its force again closes the waste valve, D, and a second 

 portion of water is driven into the reservoir as before, 

 and so it repeatedly continues. The great force of the 

 compressed air in the reservoir drives the water up the 

 discharge-pipe, C, to any required height or distance. 



The mere weight of the water will only cause it to 

 rise as high as the fountain-head ; hut like the mo- 

 mentum of a hammer, which drives a »ail into a solid 

 team, which a hundred pounds would not do by press- 

 ure, the striking force of the stream exerts great 

 power. 



The discharge-pipe, C, is usually half an inch in di- 

 ameter, and the supply -pipe should not be less than an 

 inch. A fall of two or three feet in the stream, with 

 not less than half a gallon of water per minute, with 

 a supply-pipe forty feet long, will elevate water to a 

 height as great as the strength of common half-inch 

 lead pipe will bear.* The greater the height in pro- 

 portion to the fall of the stream, the less will be the 

 quantity of water elevated as compared with the quan- 

 tity flowing in the stream. 



Unlike a pump, there is no friction or rubbing of 

 parts in the water-ram, and it will act for years with- 

 out repairs, continuing thi'ough day and night its 



* When water is raised to a considerable elevation by means of the 

 water-ram, the reservoir must possess great strength. If the height 

 be one hundred feet, the pressure, as shown on a former page, is about 

 forty-four pounds to the square inch. With an internal surface, there- 

 fore, of only two square feet, the force exerted by the column of water, 

 tending to burst the reservoir, would be equal to more than twelve 

 thousand pounds. 



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