FRICTION. 247 



And that this is the case will not now be con- 

 tested. Is it not then somewhat remarkable that 

 the same laws which produce a state of permanent 

 motion in the heavens, should, on the earth, give 

 rise to a condition in which rest is the rule and 

 motion the exception ? The air, the waters, and 

 the lighter portions of matter are, no doubt, in a 

 state of perpetual movement ; over these friction 

 has no empire : yet even their motions are in- 

 terrupted, alternate, variable, and on the whole 

 slight deviations from the condition of equilibrium. 

 But in the solid parts of the globe, rest pre- 

 dominates incomparably over motion : and this, 

 not only with regard to the portions which cohere 

 as parts of the same solid ; for the whole surface 

 of the earth is covered with loose masses, which, 

 if the power of friction were abolished, would 

 rush from their places and begin one universal 

 and interminable dance, which would make the 

 earth absolutely uninhabitable. 



If, on the other hand, the dominion of friction 

 were extended in any considerable degree into 

 the planetary spaces, there would soon be an end 

 of the system. If the planet had moved in a 

 fluid, such as the Cartesians supposed, and if this 

 fluid had been subject to the rules of friction 

 which prevail in terrestrial fluids, their motions 

 could not have been of long duration. The solar 

 system must soon have ceased to be a system of 

 revolving bodies. 



But friction is neither abolished on the earth, 



