

THE HYDROSTATIC BELLOWS. 



181 



tube, 1 or 2 cm wide, which is bent into a right angle at 

 the lower end. If water be poured into the tube, it will 

 fill the cavity of the vessel and separate the boards, and 

 by adding more water the instrument may be made 

 to support a very considerable weight. Thus, suppose 

 the upper board to have a diameter of 20 cm , that is, a 



FIG. 129 (an. proj. \ real size). 



FIG. 130 



ize}. 



radius of 10 cm , and hence a superficial area of 10 x 

 10 x 3 '14 = 314 square centimetres, and the surface of 

 the water in the tube to be 50 cm higher than the lower 

 side of the board, then the pressure upon this side which 

 tends to raise the board is equal to a weight of 314 x 

 50 = 15,700 CC of water, that is, of 15,700 grammes, or 

 15 kgr -7. 



