182 WEIGHTS EAISED BY LIQUID PRESSURE. 



The construction of the hydrostatic bellows is not quite easy, hut 

 the apparatus shown in fig. 131 may he employed for the same 

 purpose. 



A pig's bladder, or, better still, that of an ox, is cut down near its 

 mouth so far that the end of a glass tube of about the thickness of a 

 finger, and 10 cm in length, may be passed through the aperture and 



FIG. 131 (an. prqj. real size). 



firmly tied (if necessary with the help of a cork, as described on 

 page 14). A longer glass tube (about 70 cm ) is connected with the 

 shorter by a piece of tight-fitting india-rubber tube, and held in a 

 vertical position by the fork of the retort-stand. The bladder is 

 moistened, placed upon the table, flattened out as much as possible, 

 and a piece of board, such as the lid of a box, or a drawing-board, 

 laid upon it, so that the bladder is not in the middle but close to the 

 edge of the board, as seen at B in the figure. At each end of the 

 bladder small blocks of wood, K 7T, about 2 or 3 cm high, are placed, in 

 order to protect the glass tube, which reaches under the board, from 

 being broken by the pressure of the board and the weights to be 

 afterwards placed upon it. By pouring water from a bottle or 

 through a funnel into the tube the bladder is filled until the board 

 begins to rise above the blocks and is in contact with the table only 

 along the edge a b. 



