68 Dr J. C. GREGORY'S Notice concerning 



adduced by M. DUTENS to prove that the general principles of 

 motion and gravitation were known to the ancients, are precisely 

 the same as those contained in NEWTON'S manuscript, a consi- 

 derable part of which, I find, had been long before published, 

 nearly verbatim, in the preface to the " Astronomiae Physicas et 

 Geometric^ Elementa" of DAVID GREGORY *. The passage 

 from LUCRETIUS, brought forward by M. DUTENS as a proof 

 that the resistance of the medium through which they pass, was 

 known to the ancients to be the cause of the difference in the ve- 

 locity with which bodies fall, is quoted at full length by NEWTON 

 after the following remarks : " Et quamvis res leviores qua? 

 ae'ris vel aquae resistentiam difficilius vincunt in his fluidis de- 

 scendant tardius, tamen in spatio vacuo ubi nulla est resistentia, 

 atomos omnes tarn graviores quam minus graves propter gravi- 

 tatem sibi proportion alem aequali celeritate descendere, sic docet 

 LUCRETIUS :" And the two remarkable lines, 



" Omnia quapropter debent per inane quietum, 

 jEque ponderibus non aequis concita ferri, 11 



are written in large characters, with a view, evidently, to shew the 

 importance which he attached to them. 



This account of the opinions of the ancients occupies the 

 greater part of the manuscript; but attached to it there are three 

 very curious paragraphs. Two of these appear to have been the 



II est cependant aise de faire voir qiTils n'ont fait que suivre les traces des ces an- 

 ciens philosophes, en partant du meme principe, et guides par les memes raisonne- 

 mens :" p. 145. 



* It is worthy of remark, that M. DELAMBUE, in his " Histoire de 1'Astrono- 

 mie au Dixhuitieme Siecle," objects to these statements of DAVID GREGORY, as at- 

 tributing more precise ideas on the subject of gravitation to the ancients than they 

 possessed, not being aware that in so doing he was opposing not only the opinion of 

 DAVID GREGORY, but that of NEWTON himself. 



