64 OF FLUID PRESSURE ON THE SIDES AND BASE OF CUBICAL VESSELS. 



co-efficient 187.5, the product will express the number of Ibs. to 

 which the pressure on the bottom and the four upright sides is 

 equivalent. 



76. EXAMPLE 13. Suppose the length of the side of a cubical 

 cistern to be 35 feet ; what is the pressure sustained by it, when it is 

 completely filled with water ? 



Here we have given, b zz 35 feet ; therefore, by proceeding accord- 

 ing to the composition of the foregoing equation, we shall obtain 



p' = 35 X 35 x 35 X 187.5= 8039062.5 Ibs. 

 Hence it appears, that the aggregate pressure upon the bottom 

 and the upright surface of a cubical vessel whose side is 35 feet, 

 is 8039062.5 Ibs. or 



8039062.5 -f- 2240 = 3588.867 tons, 



while the absolute weight of the contained fluid, is only one third 

 of that quantity, or 



35 X 35 x 35 X62.5 -; 2240 = 1196.289 tons. 



77. EXAMPLE 14. Let the dimensions of the vessel remain as in the 

 preceding example, and suppose it to be filled with wine, of which the 

 specific gravity is .96, instead of water, whose specific gravity is unity, 

 what pressure does it then sustain ? 



For the weight of a cubic foot of wine, we have 



1 : 62.5 : : .96 : 60 Ibs. 



and the pressure on the bottom and sides of a vessel containing a 

 cubic foot is 60 X 3 zz: 180 Ibs. ; consequently, the pressure on the 

 bottom and sides of a vessel whose side is 35 feet, is 



p' = 35 X 35 X 35 X 180 = 7717500 Ibs., 

 and this, by reducing it to tons, is 



= 3445 - 3125 tons ' ; :" 



while the absolute weight of the contained fluid, is only one-third of 

 that quantity, or 



35 X 35 X 35 x 60 4- 2240 = 1 148.4375 tons. 



