On the. Hypothesis of Gaseous Repulsion. 19 



to controvert, on light grounds, the views, that illustrious phi- 

 losopher supposes he has proved. So far however is Newton 

 from conceiving he has established repulsion, that he even 

 calls in question the existence of attraction; a property as much 

 the more plausible, as it appears to be more common. " And to 

 show," says he, " that I do not take gravity to be an essential 

 property of bodies, I have added one question concerning its 

 cause," &c. — Adverfiseinryit the second to his Optics. 



After such explicit statements as these, it is somewhat ex- 

 traordinary that the authority of Newton should be advanced 

 in confirmation of gaseous repulsion. That great philosopher, 

 whatever use he may have made of ihe hypothesis of repulsion 

 for want of a better, could never, with his views of the nature 

 of heat, as might be easily shown, have believed repidsion to 

 be the cause of gaseous elasticity. Hence I apprehend arises 

 his cautious manner of proposing it ; and his wish to precede 

 confidence by further inquiry. But so unaccountably anxious 

 are men for the authority of Newton to sanction their peculiar 

 notions ; and so safe do they think their views if a passage from 

 him can be wrested to their support, that I have not only seen 

 him quoted in undisputed corroboration of what he merely 

 favoured, but he has actually been made to sanction that to 

 •which he is decidedly and notoriously hostile. Thus, it is not 

 only attraction and repulsion, on the hypothesis of which he 

 has made such brilliant discoveries, he is erroneously forced 

 to have proved, but he has been made to supj)ort caloric, 

 the opposite hypothesis to that which he admits. He has, if 

 I recollect rightly, been quoted by Dr. Young, to favour the 

 propagation of light by pressure, which it is well known he 

 has indisputably disproved ; and I am informed he has even 

 been put at the head of atheists, though one of the most pious 

 and virtuous men that ever existed ! 



I have thought it necessary to premise this nuich, lest I 

 should again be unfairly and falsely charged, as I have already 

 been, with temerarious opposition to Newton ; to whose views, 

 I repeat, I think it no do-ogation to acknowledge, if my labours 

 have been successful, 1 am chiefly indebted. 



The density being proportional to the compression, the 

 phHpnomena of i-e|ielling forces to which Newton has arrived, 

 are, ' that the centrifugal l()rces reach to and terminate in the 

 next paiticles, or at most are dilfused but a little further, and 

 that the intensity of re|)ulsi<)n is reci|)rocally as the distance.' 

 Any observations on the singular whim nature must display 

 in operating by forc«!s so limited as to terminate in the nearest 

 particles, however nuich the air may be ccmdensed, and yet 

 so indelinile'y extensive as to reach them with tlie same limita- 

 C 2 tio" 



