264 HISTORY OF SCIENCE. 



being nearly in the same line of sight ; that is, stars physically double 

 were to be by this term distinguished from those which were merely 

 optically double. After observations extending over twenty-five years, 

 Herschel was able to enumerate fifty instances of binary stars ; but 

 more than ten times that number have since been recognized. 



The name of " fixed stars " has been found to well express the diffe- 

 rence between these bodies on the one hand, and planets and comets 

 on the other; but, besides those movements of binary stars just named, 

 it was found by Halley, in 1717, by comparing the anciently recorded 

 positions of the three conspicuous stars, Sirius, Arcturus, and Alde- 

 baran, with his own observations, that after all corrections, there re- 

 mained certain discrepancies, the apparent changes in latitude amount- 

 ing to 37', 42', and 33' respectively. W. Herschel's observations placed 

 the existence of proper motions of the fixed stars beyond a doubt, and 

 from a comparison of the various cases, he was led to infer that the 

 solar system was moving towards a point in the constellation Hercules, 

 and his conclusion has been since confirmed from results obtained by 

 other observers. 



The foregoing paragraphs can give but a feeble idea of the extent of 

 Herschel's labours, and of the striking originality of his speculations. 

 Of the life of this great astronomer we have but few particulars to add. 

 He received the honour of knighthood from the Prince Regent in 1816, 

 and the University of Oxford, by no means hasty in recognizing the 

 merits of the greatest astronomical observer of his age, conferred upon 

 him an honorary degree a few years before his death. Sir W. Herschel 

 lived till 1822, and died full of years and honours on the 23rd of August, 

 when he had nearly completed his eighty-fourth year, leaving a son, 

 Sir John Herschel, whose career, as will be seen, worthily maintained 

 the name of Herschel in the annals of science. 



The priority of invention of the differential calculus was, as we have 

 indicated, disputed between Newton and Leibnitz, and the claims of 

 each were hotly maintained by their respective partizans. The bitterness 

 with which this controversy was carried on ultimately caused an almost 

 complete cessation of scientific intercourse between the British and the 

 Continental mathematicians. Each party followed the steps of its own 

 great leader, regardless of the development of the rival system. The 

 British mathematicians, in particular, were completely ignorant of the 

 improvements which their Continental brethren rapidly effected in the 

 differential calculus, and adhered rigidly to the very letter of the me- 

 thods of fluxions. They seemed to have been so dazzled by the splen- 

 dour of Newton's discoveries, that they could not imagine that his 

 methods might be capable of extension and improvement. Adhering 

 to the idea and notation of fluxions exactly as Newton had delivered 

 them, they were able to apply the new calculus to very few problems 

 beyond those which obviously admitted of such application. The Con- 

 tinental mathematicians, on the other hand, found the fundamental 



