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 at- 

 traction 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 re- 

 pelled 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 be 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 

 all the smaller motions of their 

 particles through some other at- 

 tracting and repelling force, which 

 exists mutually between those 

 particles" (' Optiee,' 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 Friend (' Lectiones Chy- 

 micse'), 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 capillary, ac- 

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

 quoted by Laplace in his ' The"orie 



de FAction capillaire,' which forms 

 the supplement to the tenth book of 

 the ' Me"canique 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 off with query 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 " probability of a medium more 

 subtle than air " and the " me- 

 chanical efficient of gravity." 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 ex- 

 periments." 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 

 primary quality of matter. From 

 his correspondence with Cotes, 

 edited by Eddleston (1850), we 

 know that Newton in composing 

 the " Scholium generate," 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). 



