Meanwhile, in 1886, _Arthur Auwers_, permanent Secretary of the Berlin Academy of Sciences, completed the re-reduction of Bradley’s observations at Greenwich, and brought out 300 reliable proper motions, which were utilised by Ludwig Struve, whose investigation removed the solar apex from Hercules to the neighbouring constellation Lyra: this slight change was confirmed by _Oscar Stumpe_, of Bonn, and _Lewis_ _Boss_ (born 1847), director of the Observatory at Albany, New York. An investigation by Newcomb fully confirmed the previous results. In 1900, 1901, and 1902 Kapteyn made three distinct investigations on the solar motion, and still further confirmed the previous investigations. These investigations are fully confirmed by the application to the question of Doppler’s principle of measuring radial motion. The spectroscopic researches of Campbell at the Lick Observatory place the solar apex very near the position assigned to it by Newcomb and Kapteyn. Campbell finds the solar velocity to be about 12 miles a second, and Kapteyn thinks a velocity of about 11 miles a second is “the most probable value that can at present be adopted.” CHAPTER X. THE LIGHT OF THE STARS. “That a science of stellar chemistry should not only have become possible, but should already have made material advances, is assuredly one of the most amazing features in the swift progress of knowledge our age has witnessed.” So writes Miss Agnes Mary Clerke, the historian of modern astronomy. As long ago as 1823 Fraunhofer observed the spectra of the brighter stars, and gathered the first hint of the grouping of the stars into three classes. Then, after Fraunhofer’s death, the subject lay in abeyance for thirty-seven years. At length, in 1860, on Kirchhoff’s explanation of the Fraunhofer lines, the study of stellar spectra was inaugurated at Florence by Donati, who carefully fixed the positions of the more important lines. His instrumental means, however, were very limited, and his observations were not successful. In 1862 Rutherfurd, in New York, commenced the study of stellar spectra, but shortly afterwards turned his attention to astronomical photography. The actual founders of stellar spectroscopy were the eminent Italian observer, Angelo Secchi, and the illustrious Englishman, William Huggins.