54 



TUB APPLICATIONS OF PHYSICAL FORCES. [BOOK i. 



handle or beam is fixed to the machine, worked by two or several men, 

 or the pump is driven by a crank connected with a steam-engine. 



The kind of motive power which gives the up-and-down movement 

 to pumps may also be very various. Ordinary pumps, intended for 

 domestic purposes, and of small sizes, are fitted with levers, oscillating 

 on a fixed point, moved by the arm or by a wheel turned by the same 

 means. 



FIG. 35. Pump with crank and fly-wheel. 



Fio. 36. Bramah's oscillating pump. C, a, 

 a', suction tube and valves. A, A', spaces 

 separated by a partition. DD', piston os- 

 cillating round the axis 0'. Om, handle 

 giving movement to the piston. 



But when more considerable strength is required .for powerful 

 pumps, the motive power is sometimes a horse-power machine, some- 

 times steam, and sometimes the force developed by a fall of water. 

 The elevating machine at the bridge of Notre Dame, pulled down 

 several years ago, was a pump moved by means of hydraulic wheels 

 fixed at a point of the Seine where the rapidity of the current gave a 

 considerable disposable force. In the old machine at Marly, which 

 raised the waters of the Seine to the royal castles of Marly and 

 Versailles, by giving motion to 221 pumps, fourteen were of the same 



