24 PHILOSOPHICAL TRANSACTIONS. [aNNO 1665. 



proportions between these two, for burning bodies of other colours. Whence he 

 has drawn some consequences, touching the distance at which we may hope 

 to burn bodies here by the means of great glasses and great looking glasses. 

 So that we must yet be seven times nearer the sun than we are to be in danger 

 of being burned by it. Where he mentions, that having given instructions to 

 certain persons gone to travel in hot countries, he has, among other particu- 

 lars, recommended to them to try, by means of large burning glasses, with how 

 much less aperture they will burn there than here, to know from thence whe- 

 ther there be more light there than here; and how much; since this perhaps 

 may be the only means of trying it, supposing the same matters be used: 

 although the difference of the air already heated, both in hot countries and in 

 the planets that are nearer than we, may alter, if not the quantity of light, at 

 least that of the heat found there. 



Afu7^ther Account, touching Signior Campani's Booh and Performances 

 about Optic Glasses. By M. Auzout. N" 4., p. 69. 



In the above-mentioned French tract there is also contained M. Auzout's 

 opinion of what he had found new in the Treatise of Signior Campani, which 

 was spoken of in the first papers of these Transactions, concerning both the ef- 

 fect of the telescopes, contrived after a peculiar way by the said Campani at 

 Rome, and his new observations of Saturn and Jupiter, made with them. 



First, therefore, after M. Auzout had raised some scruple against the contri- 

 .vance of Signior Campani for making great optic glasses without moulds, by the 

 means of a turn-lath, he examines the observations made with such glasses : 

 where, having commended Campani's sincerity in relating what he thought he 

 saw in Saturn, without accommodating it to M. Huygens's hypothesis, he affirms, 

 that supposing there be a ring about Saturn, Signior Campani could not see, in 

 all those different times in which he observed it, the same appearances which 

 he notes to have actually seen. For, having seen it sometimes in trine aspect 

 with the sun, and oriental; sometimes in the same aspect, but occidental; some- 

 times in sextile aspect, and occidental ; at another time again in trine, and ori- 

 ental ; this author cannot conceive how Saturn could in all these different times 

 have a difference in its phasis, or keep always the same shadow; seeing that, 

 according to the hypothesis of the ring, when it was oriental, it must cast the 

 shadow upon the left side of the ring beneath, without casting any on the right 

 side ; and when it was occidental, it could not but cast it on the right side be- 

 neath, and nothing of it on the other. 



M. Auzout believes, that he was one of the first that well observed this sha- 

 dow of Saturn's body upon his ring ; which he affirms happened two years since. 



