6 Meldrum, Developmoit of the Atomic Theory . 



then, whatever was sound in Descartes he retauied and 

 assimilated. Boyle and Hooke had studied Descartes, 

 and Newton studied all three. In a letter to Hooke, 

 dated Feb. 5th, 1675/6, on the subject of light, he 

 admits his indebtedness to others. " You defer too 

 much to my ability in searching into this subject. What 

 Descartes did was a good step. You have added much 

 several ways, and especially in considering the colours of 

 thin plates. If I have seen further, it is by standing on 

 the shoulders of giants." ^'" 



Newton, in his speculaiions on the disintegration of 

 atoms, in Query 31 of the "Optics," had no unusual 

 physical phenomenon in viev.' at the time. He was 

 simply improving on Descartes," whose theory on the 

 subject seems crude enough.'' 



In contrast to the speculative topic of disintegration, 

 another problem which interested Newton was a perfectly 

 concrete one. This was Boyle's law, made known in the 

 year 1662, that the volume of a given quantity of air is 

 inversely proportional to the pressure. Newton's theory 

 of gravitation was based on the assumption that every 

 particle of matter attracts every other particle. In ex- 

 plaining Boyle's law he made the very different assumption 

 that air is composed of particles which repel one another. 



This conception of the atmosphere, as being composed 

 of " particles mutually repulsive," was in all probability 

 derived from Descartes. Boyle, in the passage already 

 quoted, where he explains the Cartesian theory, says that 

 in the air, "each corpuscle endeavours to beat off all 

 others from coming within the little sphere requisite to its 

 motion about its own centre." 



^•'' Brew.ster's " Life of Newton," vol. I, p. 142. 

 '■' CEuvres, ed. by Cousin, vol. 4, pp. 266-268. 



^ ^ I am indebted to my friend, Mr. J. R. Partington, B.Sc, for pointing 

 out to me that Descartes was the source of Newton's ideas on disintegration. 



