7 8o POPULAR SCIENCE MONTHLY. 



between any two bodies would at once disturb the equilibrium 

 existing between them and other bodies, and so tend to produce 

 an unending series of readjustments. Furthermore, equalization 

 with respect to any one quality or tendency does not mean equal- 

 ization with respect to all. We have thus a twofold source of 

 variation, and the conception of eternal change becomes at once 

 less impossible than the conception of eternal rest. In addition, 

 the doctrine of the dissipation of energy involves a fatal contra- 

 diction. If the world be running down by the conversion of all 

 available energy into heat, how comes it about that the universe 

 is at the same time cooling off by the loss of heat ? The answer 

 that the heat energy is being transferred to the ether is not satis- 

 fying, and it is particularly unsatisfying if one does not believe 

 in the ether. An examination of the phenomena would lead one 

 to the very contrary conclusion that the world machine is not 

 running down and that the universe is not cooling off. 



The third book, on phenomenology, starts out with the denial 

 of " force " and " energy " as separate physical entities, and seeks 

 to find an explanation of acceleration and retardation, heat and 

 molecular reaction, electricity and magnetism, conduction and in- 

 duction, in terms of persistence, resistance, reciprocity, and equal- 

 ization. Energy is regarded not as a cause of phenomena, but as 

 a result, while "force" is dismissed as a metaphysical pitfall 

 which has already claimed too many victims. The attempt is 

 necessarily somewhat lengthy (it occupies two hundred pages), 

 and the more so since the milk of human kindness in these two 

 writers has not yet been condensed, but in the main it is a very 

 successful attempt. It proceeds upon the true scientific principle 

 the search for similarities rather than for differences. 



The same book also takes up the much- discussed question of 

 action at a distance. We all remember Newton's words : " That 

 gravitation should be innate, inherent, and essential to matter, so 

 that one body may act on another at a distance through a vacuum 

 without the mediation of anything else, by and through which 

 their action and force may be conveyed from one to another, is to 

 me so great an absurdity that I believe no man who in philosoph- 

 ical matters has a competent faculty of thinking can ever fall 

 into it." But experience shows that equalization between two 

 bodies in different states of excitation takes place the more readily 

 in proportion as the intervening resistance is less. It is a natural 

 inference, therefore, that the very most favorable condition for 

 such equalization would be the absence of all resistance that is, 

 the absence of any intervening medium. Experiments with 

 vacuum tubes confirm this inference. The more perfect the ex- 

 haustion the more perfect the transmission ; and this is true not 

 only of heat, light, and electricity, but as well of gravity itself, 



