Double Actiny Pump. 



551 



raised one-half of the water passes into the discharge pipe, 

 while the other one-half rises into the smaller cvlinder 

 which,, with the down 

 stroke, must be forced out 

 through the discharge pipe, 

 in this way dividing the la- 

 bor between the two strokes 

 of the pump. In other 

 forms <;f pumps the same 

 result is accomplished by 

 arranging an air chamber 

 in connection with the cyl- 

 inder in such a way that, 

 when The up stroke is made, 

 a part of the w r ater rises 

 into the air chamber, com- 

 pressing the air to such an 

 extent that while the down 

 stroke of the piston is being 

 made the air expands, forc- 

 ing the water out, thus se- 

 curing double action. 



698. Proper Place for the 

 Cylinder in the Well. The 

 maximum night to which 

 the air pressure can sustain 

 a column of water at sea 

 level is' only about 34 feet. 

 13ut the imperfect action of 

 the best suction pumps, to- 

 gether with the pressure 

 exerted by the water vapor 

 and the air escaping from 

 the water when a high 

 vacuum is produced over 



it, makes it impracticable to have the pi-ton place.] 

 than 1C to 20 feet al>ve water in the well. 



I'].,. L^J).- Double acting Miction \ \rn\\) 



