68 CORRELATION OF PHYSICAL FORCES. 



this supposition, without creation of force, the universe got out 

 of the diffuse chaotic state ; for its tendency must, ex hypothesi, 

 have always been to remain in or return to it ; and if all other 

 forces resolve themselves into heat, and heat is nowhere re- 

 concentrated, but disperses itself through the universe until 

 all acquires an uniform temperature, the theory of the Con- 

 servation of Energy is erroneous, for, as at the ultimate equal 

 distribution all will be immobile and unchangeable, every 

 year, month, hour or minute that state is being gradually 

 approached, and so every minute some amount of active force 

 is being lost ; thus force, or energy (the term preferred) is not 

 ' conserved,' but is in gradual progress of neutralisation, which 

 virtually amounts to annihilation of force. There are so 

 many circumstances of difficulty attending cosmical specula- 

 tions, that but little reliance can be placed upon the most 

 profound. We know not the original source of terrestrial 

 heat, still less that of solar heat ; we know not whether or not 

 systems of planets may be so constituted as to communicate 

 forces, inter se, so that forces which have hitherto escaped 

 detection may be in a continuous or recurring state of inter- 

 change. 



The movements produced by mutual gravitation may be 

 the means of calling into existence molecular forces within 

 the substances of the planets themselves. As neither from 

 observation, nor from deduction, can we fix or conjecture any 

 boundary to the universe of stellar orbs, as each advance in 

 telescopic power gives us a new shell, so to speak, of stars, we 

 may regard our globe, in the limit, as surrounded by a sphere 

 of matter radiating and absorbing heat, light, and possibly 

 other forces. 



Such stellar radiations would not, from the evidence we 

 have at present, appear sufficient to supply the loss of heat 

 by terrestrial radiations ; but it is quite conceivable that the 

 whole solar system may pass through portions of space 

 having different temperatures, as was suggested, I believe, by 

 Poisson ; that as we have a terrestrial summer and winter, so 

 there may be a solar or systematic summer and winter, in 

 which case the heat lost during the latter period might be 

 restored during the former, The amount of the radiations 



