DISCOVERY OF NEPTUNE. 127 



my husband on the reception of the news by Astronomers 1846. 

 may be understood. 



This discovery was an instance of that law of progress 

 by which we find that a truth, when the time has come 

 for its reception, is seldom the prize of one mind only : it 

 may be that some far-seeing solitary minds have early 

 anticipated the knowledge for which the world is not pre- 

 pared, but in its full advent a new truth has more than 

 one recipient. It was so in the case of Neptune. In 

 observing the place of Uranus early in this century, Aberra- 

 Astronomers had found that the observable course of the Uranus, 

 newly discovered planet did not coincide with that given 

 by mathematical calculation. This appeared from M. 

 Bouvard's tables of Uranus from 1781 to 1821. Other 

 irregularities were found, but the idea of a large dis- 

 turbing body wa,s not generally entertained ; and M. 

 Poinsot, who had called the attention of the French 

 Institute to the observation of a star, supposed to be 

 a new planet, by Messrs. Wartmann and Cacciatore, 

 was laughed at. It is true that in 1834 Dr. Hussey 

 wrote to Mr. Airy that he had conjectured the possibility 

 of some disturbing body near Uranus, and that he had 

 found that MM. Bouvard and Haussen had corresponded 

 on the subject. Mr. Airy, however, was doubtful of the 

 possibility of determining the place of the planet until 

 the nature of the irregularity should be better known. 

 Eight years before the actual discovery Bessel gave it as 

 his opinion to Sir John Herschel that the disturbances in 

 question could be due only to the action of a large body 

 beyond the orbit of Uranus. The direction of investi- 

 gation was thus to a certain extent pointed out ; it was no 

 less, when attained, ' the greatest triumph of inductive 

 Science which Astronomy has yet to record.' This great- 

 ness consisted in the fact that the exact place of the planet 

 was obtained not by actual observation, but by mathema- 

 tical calculation, founded upon the elements furnished by 

 the action of the disturbing forces. ' Two Mathematicians 



