PHYSICAL SCIENCES 53 



' The meeting was memorable for the galaxy of 

 mathematicians which assembled under the presi- 

 dency of Professor Henry J. S. Smith. In the 

 small meeting-room were gathered together Clerk 

 Maxwell, Cayley, Sylvester, W. K. Clifford, Spottis- 

 woode, and J. W. L. Glaisher, the last being chief 

 Secretary of the Section ; also Robert S. Ball, then 

 speaking on his theory of screws, Osborne Reynolds, 

 Balfour Stewart, J. D. Everett, Arthur Schuster, 

 Alexander Herschel, and George Forbes : M. Janssen 

 was also present, William Huggins, and Lord Rayleigh. 

 Several other pure mathematicians were present, 

 including the Rev. Robert Harley. The result of 

 the meeting was to awaken a keen enthusiasm for 

 the intricacies of pure mathematics. One of the 

 evening lectures was that memorable discourse by 

 Clerk Maxwell on molecules, now accessible in his 

 reprinted papers, given in a manner which riveted 

 the attention of the audience. It was a serious 

 contribution to molecular physics at that period, and 

 incidentally it serves to show how absolutely remote 

 was the notion of atomic constitution and variability. ' 

 In this connexion reference is due to a much earlier 

 noteworthy event in the annals of the Association. 

 At the Sheffield meeting in 1879, Crookes delivered 

 a discourse on radiant matter, in the course of which 

 he demonstrated for the first time many of the 

 mechanical thermal and phosphorescent properties 

 of the stream of electrons in a vacuum tube, now 

 known as cathode rays. On this foundation the 

 science of radio-activity was subsequently built. 



In the volume by Schuster and Shipley already 

 cited, it is shown how, as far as concerns physical 

 science, ' in the seventies of last century, it was 



