Hydrostatics. 39 



unless a column equal to i k press against it, and 

 keep it in its place. Since therefore the particle 

 h would be raised towards the top of the vessel, 

 unless restrained by a pressure quite equal to the 

 column i A;, it follows, that two columns of water, 

 to be in equilibrium, must be perfectly on a level 

 at their surface. 



On this principle we are enabled to account 

 for springs, which are sometimes found on the 

 tops of mountains. They, in fact, come from 

 some waters which are situated upon mountains 

 higher still, and flow through canals or natural 

 pipes, which proceed under ground, perhaps for 

 the distance of miles. 



It is upon these facts the maxim is founded, 

 which has led to the hydrostatic paradox, and 

 that is, that the pressure of fluids is not in pro- 

 portion to their quantity, but in proportion to 

 their perpendicular height; and from this the 

 supposed paradox follows, that a given quantity 

 of water may exert a force two or three hundred 

 times greater or less, according to the manner in 

 which it is employed. 



To make this plain, we will take three vessels 

 of the same height, and the same base, though 

 differing materially with respect to their forms, 

 and the quantities they contain, viz. A, B, C, D, 

 %. 13. E, F, G, H, fig. 11. L, M, N, O, P, Q, 

 fig. 12. Now it may very easily be understood, 

 that the vessel fig. 15, is pressed at the bottom 

 B, C, by the whole mass of water it contains, and 



