Manchester Memoirs, Vol. Hi. (1908), No. 10. 



THE WILDE LECTURE. 

 X. On the Physical Aspect of the Atomic Theory. 



By Professor J. Larmor, Sec.R.S. 



Ddive7-ed March 3rd, igo8. 



When Descartes proceeded methodically to shake 

 himself free from the trammels of the scholastic philosophy, 

 and to reconstruct the content of his knowledge on what 

 is essentially the modern basis, he found among other 

 things — some of them now fantastic — that it was unin- 

 telligible to suppose that matter could act where it was 

 not, i.e., could produce an influence in regions with which 

 it was not in continuous structural connexion. So 

 powerfully did this feeling dominate his thought, that he 

 appears to have been unable to form any conception of 

 mere empty space as distinct from some mode of 

 occupation of it : to him, space was 3. plemim, the seat of 

 the processes of communication between the sensible 

 objects which it contains. Direct interaction of these 

 objects across distances, with mere nothingness between, 

 was not a satisfying account of the relations between the 

 apparently discrete masses which constitute our sensible 

 universe. 



The modern idea of an aethereal medium, as a means 

 of transmission of physical influences from mass to mass, 

 receives its first systematic exposition in his physical 

 writings. The Sun is for him the centre of a great 

 aethereal vortex, by which the planets are swept round in 

 their orbits ; light consists of impulsion or pressure 

 propagated through the fluid plenum. An attempt is 



March 2Sth, igo8. 



