NEW MECHANICS AND ASTRONOMY. 247 



repel instead of attracting us. For all these reasons, 

 the light that would enable us to explain attraction 

 would require to be much more akin to Rontgen's 

 X rays than to ordinary light. 



Furthermore, the X rays will not do. However 

 penetrating they may appear to us, they cannot pass 

 through the whole Earth, and we must accordingly 

 imagine X' rays much more penetrating than the 

 ordinary X rays. Then a portion of the energy of 

 these X' rays must be destroyed, as otherwise there 

 would be no attraction. If w^e do not wish it to be 

 transformed into heat, which would lead to the pro- 

 duction of an enormous heat, we must admit that it 

 is radiated in all directions in the form of secondary 

 rays, which we may call X" rays, which must be much 

 more penetrating even than the X' rays, failing which 

 they would in their turn disturb the phenomena of 

 attraction. 



Such are the complicated hypotheses to which we 

 are led when we seek to make Lesage's theory tenable. 



But all that has been said assumes the ordinary 

 laws of Mechanics. Will the case be stronger if we 

 admit the new Dynamics ? And in the first place, can 

 we preserve the Principle of Relativity ? First let us 

 give Lesage's theory its original form, and imagine 

 space furrowed by material corpuscles. If these 

 corpuscles were perfectly elastic, the laws of their 

 collision would be in conformity with this Principle 

 of Relativity, but we know that in that case their effect 

 would be nil. We must therefore suppose that these 

 corpuscles are not elastic ; and then it is difficult to 

 imagine a law of collision compatible with the Prin- 

 ciple of Relativity. Besides, we should still get a 



