XXI.] THE SIMPLEST ELEMENTS APPEAR FIRST. 167 



perturbations of spectral lines. Mr. Preston, in discussing the bear- 

 ings of his results, thus writes : * 



" We have, I think, reasonable hope that the time is fast approach- 

 ing when intimate relations, if not identity, will be seen to exist 

 between forms of matter which have heretofore been considered as 

 quite distinct. Important spectroscopic information pointing in this 

 same direction has been gleaned through a long series of observations 

 by Sir Norman Lockyer, on the spectra of the fixed stars, and on the 

 different spectra yielded by the same substance at different tempera- 

 tures. These observations lend some support to the idea, so long 

 entertained merely as a speculation, that all the various kinds of 

 matter, all the various so-called chemical elements, may be built up in 

 some way of the same fundamental substance." 



In the same way Professor J. J. Thomson, in his important investi- 

 gations of the cathode rays, after describing a new series of facts, 

 writes : f 



" The explanation which seems to me to account in the most simple 

 and straightforward manner for the facts is founded on a view of the 

 constitution of the chemical elements which has been favourably enter- 

 tained by many chemists : this view is that the atoms of the different 

 chemical elements are different aggregations of atoms of the same 

 kind. In the form in which this hypothesis was enunciated by Prout, 

 the atoms of the different elements were hydrogen atoms ; in this 

 precise form the hypothesis is not tenable, but if we substitute for 

 hydrogen some unknown primordial substance X, there is nothing 

 known which is inconsistent with this hypothesis, which is one which 

 has been recently supported by Sir Norman Lockyer, for reasons 

 derived from the study of the stellar spectra." 



On these points we must now go more into details. 



* Nature, vol. Ix, p. 180. 

 f Phil, Mag., 1897, p. 311. 



