32 FORESHADOWING OF THE ELECTRON [CH. iv. 



they were flying with ordinary molecular speed, but 

 with a long free path much longer than would have 

 been expected from ordinary gaseous theory. The 

 extraordinary length of free path was somewhat 

 difficult to reconcile with the doctrine that they were 

 flying atoms obedient to the ordinary laws of gases ; 

 'except that, being subject to electrical propulsion all 

 in the same direction, their course was more regular, 

 and their encounters therefore fewer, or less effective 

 in causing deflection, than if they had been moving 

 at random. This same feature of regularity it is 

 which confers momentum upon them ; their motion 

 does not constitute heat, and is not to be considered 

 as corresponding to temperature ; they are moving 

 in orderly succession like an army or like a wind, 

 rather than with the irregular unorganised motion 

 appropriate, and solely appropriate, to the terms 

 " heat " and " temperature," and to the ordinary 

 kinetic theory of gases. Crookes indeed hazarded the 

 surmise by one of those flashes of intuition which 

 are sometimes vouchsafed to a discoverer but are often 

 ridiculed by representatives of orthodox science at the 

 time that he had obtained matter in "a fourth 

 state ; " and even that he had got in his tube some- 

 thing equivalent to what was contemplated in the 

 " corpuscular " theory of light. There is some cor- 

 respondence with fact even in this last mode of 

 statement, when the particles are moving quickly 

 enough, for a nuclear wave- front or ether-pulse is 

 then travelling with them ; but how true the first 

 was that the matter in the dark space was in a 

 fourth state, neither solid nor liquid nor gaseous 

 how true that was we shall presently see. 



Meanwhile let us summarise the evidence for the 

 view that the cathode rays are at any rate charged 



