59 



the water is contained ; D and E are two forcing 

 pumps, wrought by the lever FG, moving on the 

 centre h. The easiest mode of supplying the en- 

 gine with water, is that which is usually employed 

 in London in cases of fire, when a leather pipe 

 communicates with the orifice of one of the pipes 

 which supplies the city with water. When this 

 cannot be done, the water is poured by .-buckets 

 into the vessel AB, and being strained through 

 the wire grating N, is, by the pressure of the 

 atmosphere, raised (as before described in treat- 

 ing of the forcing pump) through the valves at 

 the lower end of the barrels D and E, when 

 either of the forcers ascend, and at their descent 

 it will be forced through the other valves alter- 

 nately, into the air vessel C : the air, therefore, 

 in this vessel being very strongly compressed, by 

 its spring it will force the water up through the 

 metal pipe within the air vessel; the part Q of 

 which being flexible, its end may be directed to 

 any part of the building where the flames predo- 

 minate. 



By the means of forcing pumps water may be 

 raised to any height above the level of a stream 

 or spring, provided the machinery is sufficiently 

 powerful to work them. The London Bridge 

 water-works, which supply the city of London 

 with water, consist of a certain number of forcing 

 pumps, which are worked by large wheels turned 

 by the tide. There is also a beautiful engine of 

 this kind at the duke of Marlborough's at Blen- 

 heim. 



