﻿Principles of Molecular Physics. 439 



Thus far there is no harm. But is it true that the nuclei and 

 envelope of each specific molecule are " assumed " by me to have 

 a regular geometric form ? The question is one of fact : every 

 one may easily satisfy himself that I in my c Molecular Mecha- 

 nics ' have not simply assumed, but proved the regularity of mo- 

 lecules in general, and clinched the demonstration by those 

 symbols Q. E. D., which Professor Norton has so well discerned 

 on a previous occasion (see Molecular Mechanics, pp. 150- 

 152). The critic may discuss my proofs if he likes; but I deny 

 that he has the right of dissembling their existence. 



Again, have I assumed, as the learned Professor says, that 

 the geometric forms of molecules are " different for each differ- 

 ent substance ? " This is another question of fact ; and the fact 

 is quite the reverse of the statement. Not only I never affirmed 

 what Professor Norton imagines, but on the contrary I went so 

 far as to maintain that the molecules of oxygen, nitrogen, chlo- 

 rine, sulphur, iodine, are all of the same geometric form, though 

 they belong to different substances (see Molecular Mechanics, 

 pp. 236-243) . Moreover, as there are from sixty to seventy differ- 

 ent primitive substances, it was as impossible for me to admit that 

 each different substance had a different regular geometric form, 

 as it would, have been to discover from sixty to seventy different 

 regular polyhedric forms. 



Transmission of force. — I hasten to say a word about the last 

 " failure M pointed out by Professor Norton in my ' Elements 

 of Molecular Mechanics/ He says : 



" We have already seen that the principle that one material point 

 acts upon another instantaneously, without the intervention of any 

 medium, is opposed to the fundamental idea that the force exerted 

 is inversely proportional to the square of the distance. This law, 

 to say the least, is an arbitrary assumption in the premisses." 



I look in vain for the page in which " we have already seen n 

 what my able critic here advances. What we have seen is only 

 his assertion that " the law of inverse squares is a consequence 

 of wave-propagation ; " but he gave no proof of it for the case 

 of elementary action, and I defy him to give one. Wave-pro- 

 pagation is propagation of motion, and regards only the pro- 

 gressive development of a series of effects and of their condi- 

 tions, not of their causality. Physicists indeed often say that 

 actions are conveyed through a material medium ; but this ex- 

 pression means only that a material medium is indispensable 

 for the progressive development of the aforesaid series of effects, 

 as I have shown in my work (p. 64) . As for the " arbitrary 

 assumption in the premisses" 1 need only remark that Pro- 

 fessor Norton neither brought forward my premisses, nor said 

 in what they consist. The reader will find them in my book 



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