HYDROSTATICS. 



427 



raise the water to the top of a tube 144 inches, or 12 

 feet in height. 



N. B. The box must be open below the moveable 

 bottom, to let in the air. Otherwise, the pressure of the 

 atmosphere would be so great upon the moveable bot- 

 tom if it be three inches in diameter, as to require 108 

 pouuds in the scale, to balance that pressure, before the 

 bottom could begin to move. 



A Machine, to be substituted in place of the common 

 Hydrostatical Bellows. 



A BCD is an oblong square box, 

 which is a round groove, as 

 at a, from top to bottom, 

 for receiving the upright 

 glass tube /, which is bent 

 to a right angle at the 

 lower end, and to that part 

 is tied the end of a large 

 bladder K, which lies in 

 the bottom of the box. 

 Over this bladder is laid 

 the moveable board L, in 

 which is fixed an upright 

 wire M ; and leaden 

 weights, N N, to the 

 amount of 16 pounds, with 

 holes in their middle, are 

 put upon the wire, over 

 the board, and press upon 

 it with all their force. 



in one end of 



The cross bar p is then put on, to secure the tube 



