THE ASTRONOMICAL VIEW OF NATURE. 



355 



very small distances to explain the refraction and in- 

 flection of light passing from empty space, or from the 



referring to attractive forces acting 

 only at small distances, he pro- 

 ceeds: "And as in algebra, when 

 the positive quantities disappear 

 and cease, negative quantities be- 

 gin ; so in mechanics, where attrac- 

 tion stops, there a repelling force 

 must come in. But that such a 

 force exists, seems to follow from 

 the reflection and inflection of the 

 rays of light. For the rays are 

 repelled by bodies in both these 

 cases, without the immediate con- 

 tact of the reflecting or inflecting 

 body. And if all this is so, then 

 the whole of nature will lie very 

 simple and similar to herself ; per- 

 forming all the great motions of 

 the heavenly bodies by the attrac- 

 tion of gravity, which exists be- 

 tween all those bodies, and almost 

 a.11 the smaller motions of their 

 particles through some other at- 

 tracting and repelling force, which 

 exists mutually between those 

 particles" (' Optice,' mdccvi., p. 

 341). The suggestions of Newton 

 regarding forces of molecular di- 

 mensions were taken up by other 

 contemporary writers and experi- 

 mentalists, and the ' Philosophical 

 Transactions' during the early 

 years of the last century contain 

 several memoirs touching on this 

 subject, notably by John Keill 

 (1708), who refers to Newton's 

 'Opticks,' and enlarges, as does 

 also John Freind (' Prelectiones 

 Chymicse '), on the usefulness of the 

 idea of molecular attraction in ex- 

 plaining chemical and physiological 

 phenomena. In the later editions 

 of the 'Opticks,' evidently in con- 

 sequence of the elaborate experi- 

 ments of Hauksbee, Newton enters 

 more fully into the question of 

 molecular, especially capillar}', ac- 

 tion ; and his last query, No. 31, is 

 quoted by Laplace in his ' Theorie 



de I'Action capillaire,' which forms 

 the supplement to the tenth book 

 of the 'Mecanique celeste.' I may 

 here mention that as some confu- 

 sion exists in the different editions 

 of the ' Optics ' regarding the num- 

 bering of the "Queries," it is best 

 to refer to Horsley's Collected Edi- 

 tion of the Works of Newton, 

 where the latest English edition is 

 reprinted, and all the variations 

 and additions noted from the first 

 (English) edition through the sub- 

 sequent ones. The first edition 

 breaks oS" with querj' 16 ; the first 

 Latin one with query 23, and this 

 was in later editions numbered 31, 

 a number of new queries being in- 

 serted, Nos. 18 to 24, referring to 

 the " j)''ob^bility of a medium more 

 subtle than air" and the "me- 

 chanical efficient of gravitj'." This 

 was added " to show " (Newton's 

 words in preface dated 16th July 

 1717) "that I do not take gravity 

 for an essential property of bodies, 

 . . . choosing to propose it by way 

 of a question, because I am not 

 yet satisfied about it by way of 

 experiments." We may note that 

 this was written a few years after 

 the second edition of the ' Principia ' 

 was published by Cotes, whose 

 preface did a good deal to occasion 

 the misunderstanding regarding 

 Newton's views on gravitation as a 

 Ijrimary quality of matter. From 

 his correspondence with Cotes, 

 edited by Eddleston (1850), we 

 know that Newton in composing 

 the "Scholium generale," which is 

 added to the second and later edi- 

 tions of the ' Principia,' had in- 

 tended to say " much more about 

 the attraction of the small par- 

 ticles of bodies," but that on second 

 thoughts he abandoned this inten- 

 tion (p. 147). 



