358 Edwin B. Frost 



in the spectrum of the sodium flame. Stokes, Balfour, Stewart, 

 Foucault, had all groped near to the truth. It was Kirchhoff, 

 whose researches were made in connection with the eminent 

 chemist, Robert Bunsen, who announced in a communication to 

 the Berlin Academy of Sciences, in 1859, the correct interpretation 

 of the dark lines in the spectrum of sun or star: they show the 

 presence of an envelope of glowing vapors around the star. 



Here, again, a tremendous expansion was instantly given to 

 the horizon of thinking people. But to astronomers it was un- 

 doubtedly a far more impressive discovery, for it was the key to 

 open the door to indefinite new realms of knowledge. Hereafter 

 the position of a heavenly body and its motions were not to be the 

 sole objects of inquiry, but their physical and chemical nature 

 were to be investigated. And one of the special features of the 

 discovery was that the spectroscope suffered no limitations from 

 distance: provided the light was bright enough for analysis, the 

 most distant star could be as well investigated as the nearest. 

 This is of immense advantage, for in practically all investigations 

 which depend upon angular motion (across the face of the sky) 

 the errors of a determination increase proportionately with the 

 distance from the earth. 



A wide field for research was opened up b}"" this discovery, and 

 the branch of astronomy known as astrophysics began its remark- 

 able development. The spectroscopic study of all celestial 

 objects was promptly undertaken: in 1864 Dr. William Huggins 

 examined the spectra of a nebula, the bright planetary nebula in 

 Draco. To his surprise, he saw no band of color, the radiation was 

 chiefly monochromatic; the nebula was gaseous. The statement 

 sounds so simple that we lose its immense significance : Here was 

 the first verification of the visions of Herschel and of La Place: 

 they could have had no thought that it would ever be possible to 

 determine the physical state and chemical constitution of the nebu- 

 lae: even the discoverer. Dr. Huggins, was at the time surprised — 

 he had not suspected the simple result. This was one of the many 

 pioneer discoveries of this fine modern example of a genuine old 

 master of his science, the grand old man of astrophysics, whose 

 death last month, at the age of eighty-six, in the fullness of his 

 mental powers, is lamented by all astronomers. By this particu- 

 lar discovery he showed not only that the nebula was gaseous, 

 but also that it contained the omnipresent hydrogen, in addition 



