ACTION AT A DISTANCE. 



in science, and this step Newton asserted that he had made. To explain the 

 prooew by which this action is effected was a quite distinct step, and this 

 step Newton, in his Principia, does not attempt to make. 



Bat BO far was Newton from asserting that bodies really do act on oue 

 another at a distance, independently of anything between them, that in a 

 letter to Bentley, which has been quoted by Faraday in this place, he says : 



"It is inconceivable that inanimate brute matter should, without the media- 

 tion of something else, which is not material, operate upon and affect other 

 matter without mutual contact, as it must do if gravitation, in the sense of 



Epicurus, be essential and inherent in it That gravity should be innate, 



inherent, and essential to matter, so that one body can act upon anotht : 

 a distance, through a vacuum, without the mediation of anything else, by and 

 through which their action and force may be conveyed from one to another, is 

 to me so great an absurdity, that I believe no man who has in philosophical 

 matters a competent faculty of thinking can ever fall into it." 



Accordingly, we find in his Optical Queries, and in his letters to P> 

 that Newton had very early made the attempt to account for gravitation by 

 means of the pressure of a medium, and that the reason he did not publish 

 these investigations "proceeded from hence only, that he found he was 

 able, from experiment and observation, to give a satisfactory account of this 

 medium, and the manner of its operation in producing the chief phenomena of 

 nature*." 



The doctrine of direct action at a distance cannot claim for its author tin- 

 discoverer of universal gravitation. It was first asserted by Roger Cotes, in 

 his preface to the Principia, which he edited during Newton's life. According 

 to Cotes, it is by experience that we learn that all bodies gravitate. We do 

 not learn in any other way that they are extended, movable, or solid. Gravi- 

 tation, therefore, lias as much right to be considered an essential property of 

 matter as extension, mobility, or impenetrability. 



And when the Newtonian philosophy gained ground in Europe, it was the 

 opinion of Cotes rather than that of Newton that became most prevalent, till 

 at last Boscovich propounded his theory, that matter is a congeries of mathe- 

 matical points, each endowed with the power of attracting or repelling the 

 others according to fixed laws. In his world, matter is unextended, and contact 



* Maclaurin's Account of XtwtatCs Discoveriei. 



