510 EQUILIBRATION. 



indirectly by integration of those insensible motions commu- 

 nicated from the Sun, becomes, as we have seen, divided and 

 subdivided into motions less and less sensible ; until it is final- 

 ly reduced to insensible motions, and radiated from the 

 Earth in the shape of thermal undulations. In their 



totality, these complex movements of aerial, liquid, and solid 

 matter on the Earth's crust, constitute a dependent moving 

 equilibrium. As we before saw, there is traceable through- 

 out them an involved combination of rhythms. The unceas- 

 ing circulation of water from the ocean to the land, and from 

 the land back to the ocean, is a type of these various compen- 

 sating actions; which, in the midst of all the irregularities 

 produced by their mutual interferences, maintain an aver- 

 age. And in this, as in other equilibrations of the third 

 order, we see that the power from moment to moment in 

 course of dissipation, is from moment to moment renewed 

 from without: the rises and falls in the supply, being bal- 

 anced by rises and falls in the expenditures; as witness the 

 correspondence between the magnetic variations and the 

 cycle of the solar spots. But the fact it chiefly 



concerns us to observe, is, that this process must go on bring- 

 ing things ever nearer to complete rest. These mechanical 

 movements, meteorologic and geologic, which are continu- 

 ally being equilibrated, both temporarily by counter-move- 

 ments and permanently by the dissipation of such move- 

 ments and counter-movements, will slowly diminish as the 

 quantity of force received from the Sun diminishes. As the 

 insensible motions propagated to us from the centre of our 

 system become feebler, the sensible motions here produced 

 by them must decrease ; and at that remote period when the 

 solar heat has ceased to be appreciable, there will no longer 

 be any appreciable re-distributions of matter on the surface 

 of our planet. 



Thus from the highest point of view, all terrestrial 

 changes are incidents in the course of cosmical equilibration. 

 It was before pointed out, (§69) that of the incessant altera- 



