SOME THOUGHTS ON PERPETUAL MOTION. 393 



appearance in the form of motion, it reappears in the form 

 of heat. This heat seeks an equilibrium by transferring 

 itself to the colder air, in which motion reappears in the 

 heated ascending column. But this motion, in turn, disap- 

 pears when the heated column, by transference of its heat, 

 has ceased to be warmer than the contiguous air. All 

 force is seeking some affinity with which it may be at rest, 

 or it is striving to effect a motion which will bring its ac- 

 tivities to rest. In obedience to the force of gravity, rain 

 falls from the clouds, gathers itself into little rills, which, 

 uniting their forces, join arms with the brooklet, and thence 

 glide in company with the rivulet to the outlet of the val- 

 ley, and wend their way to the sea. In the deep bed of 

 the ocean the waters rest. The demand of gravity is sat- 

 isfied. The friction of ascending vapors upon the atmos- 

 phere disturbs the equilibrium of the electricities ; they 

 Hash in anger from cloud to cloud, and between the clouds 

 and the earth, ever striving to restore the equilibrium. 

 When that is effected, all the phenomena resulting from 

 electrical action cease, and would forever cease were not a 

 fresh disturbance introduced. If the electricities are again 

 disturbed, it is because some other force is seeking its equi- 

 librium. This other force is out of equilibrium because 

 some third force has created disturbance in the search for 

 its own equilibrium, and thus link hangs upon link in 

 this chain of causation. We know not how far back the 

 remotest disturbing force may lie, but of this we may be 

 certain ; there is somewhere, or will be somewhere in the 

 future, a last disturbing force. Behind this, all is rest. 

 When this has attained its equilibrium, all the phenomena 

 resulting from the struggle of the forces will cease. 



This is a mere abstract statement of the case. It pos- 

 sesses a higher significance than we may suspect. The ar 

 gument concerns the stability of the very earth on which 



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