136 ESSAYS ann OBSERVATIONS 
repulfion, is agreeable to perpetual experience ; 
and is no lefs certain, than that thefe powers 
themfelves are eftablifhed in nature. We 
find the load{tone attracts iron, and that iron 
attracts the loadftone, with equal force; and, 
becaufe they attract each other equally, they 
remain at reft when they come into contact. 
Ifa mountain, by its gravity, preffed upon 
the earth, and the earth did not reac equal- 
ly on the mountain; then the mountain 
would neceffarily carry the earth before it, by 
its preflure, with a motion accelerated 77 27- 
finritum. The fame is to be faid of a ftone, 
or the leaft part of the earth, as well as of 
a mountain. A mutual attraction too is ob- 
ferved amongft the diftant bodies of the fo- 
lar fyftem. 
Wuen a heavy body lies upon a table, and 
confequently acts upon it with its whole 
weight; there muft be an equal reaction from 
the power of cohefion of the parts of the 
table, in order to fupport the burden. In 
the fame manner, if the bottom of any vef- 
fel fuftains the weight of a certain quantity of 
fand, it muft react with a force equal to that 
weight; otherways it muft break or give way. 
The power of cohefion may indeed greatly 
exceed 
