MATTER, SPACE, AND TIME 213 



simple to complex structures containing different 

 numbers of some common sub-atom. The atomic 

 weights of many elements are nearly simple mul- 

 tiples of that of hydrogen, and Prout suggested 

 that hydrogen was the ultimate basis of other 

 elements. More accurate chemical experiments 

 did not eliminate the divergence of some atomic 

 weights from whole numbers, and Prout's hypo- 

 thesis for many years was discarded ; but the 

 idea of some common constituent in the different 

 elements has a deep scientific instinct and even 

 then some experimental evidence in its favour, 

 and only waited for definite confirmation to be 

 received as the natural conclusion of many 

 promising speculations. 



For the first time, in 1897, such definite 

 experimental confirmation was given by Professor 

 J. J. Thomson, who, in the remarkable series of 

 researches described on pages 142 to 147, clearly 

 showed that, in the cathode rays of a vacuum 

 tube, we can detect corpuscles with about the one 

 thousand eight-hundredth part of the mass of the 

 lightest atom known, that of hydrogen. These 

 corpuscles were shown to be identical, whatever 

 the nature of the residual gas in the tube, and 

 whatever the metal employed as electrode. The 

 corpuscles are common to all kinds of matter, 

 and the mind at once sees in them a common 

 constituent of all the chemical atoms. 



To explain the phenomena of radiation, that 

 is the emission of electro-magnetic waves, we must 

 suppose with Lorentz and Larmor that the parts 

 of atoms which vibrate are electrical in nature. 

 As explained above, we thus reach the idea of 

 electric units on electrons as components of 



