132 MEMOIR OF AUGUSTUS DE MORGAN. 



1846. the want of confidence in their science among Mathema- 

 ticians, received confirmation from the report, by Mr. 

 Challis, of observations at the Cambridge Observatory, 

 founded on Mr. Adams's calculations. The statement was 

 laid before the Senate in December, and in it was men- 

 tioned a memorandum made in 1841, and shown by Mr. 

 Adams to Mr. Challis, recording the writer's intention to 

 solve the problem as soon as he had taken his degree 

 of B.A. 



The unusual character of the question is adverted to 

 in this first statement of Mr. Challis : 



Mr. The usual character of perturbations is to find the disturbing 



observa- 8 action of one body on another by knowing the positions of both, 

 tions. In the case of Uranus, Mr. Adams's problem was the inverse one ; 



from known disturbances of a planet in a known position, to find 

 the place of the disturbing body at a given time. ... It will 

 appear by the above account that my success might have been 

 more complete if I had trusted more implicitly to the indications 

 of the theory. It must, however, be remembered that I was 

 quite in a novel position; the history of Astronomy does not 

 afford a parallel instance of observation undertaken entirely in 

 reliance upon deductions from theoretical calculations, and those, 

 too, of a kind before untried. . . . We may certainly assert to 

 be fact for which there is documentary evidence, that the problem 

 of determining from perturbations the place of the disturbing 

 body was first solved here ; that the planet was here first sought 

 for; that places of it were here first recorded, and that approxi- 

 mate elements of its orbit were here first deduced from observa- 

 tion. And that all this, it may be said, is entirely due to the talents 

 and labours of one individual among us, who has at once done 

 honour to the University and maintained the scientific reputa- 

 tion of the country. 



Both discoverers in due course received every possible 

 distinction at home and abroad. M. Leverrier, besides 

 other honours given to him, was elected an Associate of 

 the Eoyal Astronomical Society, and, immediately after the 

 discovery, proposed for the medal. And here a difficulty 

 arose. It was usual to give only one gold medal at any 



