. 





WEIGHTS RAISED BY LIQUID PRESSURE. 183 



The weights must not be placed over the middle of the bladder, 

 bat nearer to the edge ah, as otherwise they might fall over and 

 break the glass tube, especially if they are heavy and are raised to a 

 considerable height. When the weights are placed upon the board 

 it is pressed down until it touches the small blocks ; the water in 

 the tube E will in consequence rise somewhat, and if more water be 

 poured in, the board with the weights upon it will be again 

 gradually raised. If a pig's bladder is used, several kilogrammes 

 may be raised in this manner ; with an ox-bladder from 40 to 50 k r , 

 and if the water in the tube R is about l m high a man may be 

 raised. A large stone or any other heavy object may be used in- 

 stead of weights. It is obvious, without weighing, that the raised 

 weight is much larger than the weight of the water used. When 

 the experiment is finished, the upright tube is undamped, bent 

 downwards at one side, and the water is allowed to run into a vessel 

 placed underneath. 



The raising of a large weight by means of a small 

 quantity of water is another illustration of the previous 

 statements concerning mechanical work. The water 

 which is poured into the cavity of the bellows raises a 

 considerable weight through a small space, but the work 

 (force multiplied into space) thus performed is not 

 greater than that which is performed by the small 

 quantity of water which descends and traverses the 

 much larger space represented by the height of the 

 vertical tube. 



Instead of weights, as in the hydrostatic bellows, we 

 tay employ the downward pressure of one liquid to 

 mnteract the upward pressure of another, and thus 

 >roduce equilibrium. Fig. 132, J., represents two vessels 

 communicating at their bases. The wider vessel has a 

 sectional area of 300 square centimetres ; the narrower 

 vessel, on the left side, and the lower part of the wider, 

 as far as a 6, is filled with water, while the upper part 

 of the wider vessel contains paraffin-oil, the specific 

 gravity of which is O'S. The perpendicular distance 



