i8o SCIENCE PROGRESS 



spectrum was again hit upon by Kirchhoff and by his masterly 

 memoir the foundations of the subject were now laid wide 

 and deep. His joint work with Bunsen had resulted in a 

 double triumph : Bunsen was able to utilise it in discovering 

 two new terrestrial elements — caesium and rubidium ; Kirchhoff 

 succeeded in proving that in the remote Sun there were present 

 most of the elements known to chemists on the earth. 



It was in the midst of this activity that Huggins found his 

 opportunity : in the variety of courses that appeared feasible 

 his judgment helped him again and again to the choice of 

 fruitful openings. From the outset he saw the need of minute 

 accuracy in obtaining the exact positions of the lines in the 

 spectra investigated. He saw also that it could best be obtained 

 by direct comparisons of the spectra of metals and other 

 elements with the spectra of the stars and sun. This wisdom 

 constituted him a recognised authority from the first. Be- 

 ginning work in this field early in 1862, he and Dr. W. Allen 

 Miller elaborated the necessary appliances for their research, and 

 the next five years show a record of wonderful achievement. In 

 this period Huggins had learnt enough about the brighter stars 

 to be assured, in spite of their remoteness, of the wonderful result 

 that their chemical composition does not differ essentially from 

 that of the earth and the Sun. He had also by a single glance, 

 after much careful preparation, decided a question at which 

 Sir John Herschel had laboured many years ; and Huggins's 

 solution was in direct conflict with Herschel's, for he concluded 

 that nebulae were not star clusters inordinately remote, but 

 masses of incandescent gas. His refined apparatus was in 

 complete readiness when good fortune gave him the opportunity 

 of studying the " new star " in Corona Borealis. He was also 

 able to probe into the secret of the luminosity of comets, for his 

 continued study of terrestrial spectra enabled him to identify 

 some of that luminosity with the presence in the comets of 

 compounds containing carbon. 



These five lines of research would seem enough to occupy the 

 thought and energies of a single worker. And yet we know 

 that in addition to these studies he was engaged on two others 

 which proved to be of even deeper importance. Each of these 

 was no less than an actual foundation stone, on which the vast 

 constructions of the new astronomy lie. In one of them, 

 namely the development of the method of viewing solar 



