HYDROSTATIC BELLOWS. 



183 



much greater, or equal to many pounds, the water be- 

 ing the same in quantity, but with a much higher 

 head than before. Suppose the narrow part of the ves- 

 sel is twenty times smaller than the larger part, then, 

 m pushing the bottom up one inch, the water is driven 

 twenty inches upward in the tube. So then, accord- 

 ing to the rule of virtual velocities, it will require 

 twenty times the force, because it moves upward twen- 

 ty times faster.* This, then, is precisely similar to the 

 instance where a pound on the longer end of a steel- 

 yard balances twenty pounds on the shorter end. In 

 this instance, the upper parts, D D, of the vessel oper- 

 ate as the fulcrum of a lever, and offer resistance to the 

 sliding part as soon as the water begins to ascend the 

 tube. 



HYDROSTATIC BELLOWS. 



This principle is shown in the Hydrostatic Bellows 

 Fig. 155. {Fig. 155), which consists of two round 

 •^^ pieces of board, connected by a narrow 

 strip of strong leather ; into it is inserted 

 a long narrow tube, B, with a small fun- 

 nel, e, at the top. When water is poured 

 into this tube, it will raise a weight as 

 much greater than the weight of the 

 water in the tube as the surface of the 

 upper board exceeds the cross-section of 

 the tube. Thus, if a pound of water fills 

 Hydrostatic Bellows. ^ tubc half QXi iuch in diamctcr, and the 

 bellows is two feet in diameter, then this pound will 



* The pressure will be as great upon the bottom as if the vessel 

 continued a uniform size all the way up, as shown by the dotted lines. 



