PROFESSOR CHALLIS'S REPORT TO THE OBSERVATORY SYNDICATE, xlix 



PROFESSOR CHALLIS'S FIRST REPORT TO THE CAMBRIDGE 

 OBSERVATORY SYNDICATE UPON THE NEW PLANET 1 . 



AT a meeting of the Observatory Syndicate, held at the Observatory on December 4, 

 for the despatch of ordinary business, a strong desire having been expressed by the 

 Vice-Chancellor and the members of the Syndicate generally, to receive from me a 

 Special Report of Observatory proceedings relating to the newly-discovered Planet, drawn 

 up in such a manner, and in such detail, as would enable them to lay complete information 

 on the subject before the members of the Senate, I considered it to be my duty at once 

 to comply with this request. A new body of the solar system has been discovered, by 

 means depending on the farthest advances hitherto made in theoretical and practical 

 astronomy, and confirming, in a most remarkable manner, the theory of universal 

 gravitation. It is, therefore, on every account desirable that the members of the Senate 

 should be made fully acquainted with the part which has been taken by the Cambridge 

 Observatory, relatively to this important extension of astronomical science. The obser- 

 vations I shall have to speak of, and the reasons for undertaking them, are so closely 

 connected with theoretical calculations performed by a member of this University, to 

 account for anomalies in the motion of the planet Uranus, that the history of the former 

 necessarily involves that of the latter. I hope that for this reason, and because of the 

 peculiar nature of the circumstances, I may be allowed to make a communication less 

 formal and restricted in its character, than a mere Report of Observatory proceedings. 



The tables with which the observations of the planet Uranus have been uniformly 

 compared, were published by A. Bouvard in 1821. They are founded on a continued 

 series of observations extending from 1781, the year of its discovery, to 1821. Previous 

 to 1781, it had been accidentally observed seventeen times as a fixed star, the earliest 

 observation of this kind being one by Flamsteed in 1690. Bouvard met with a difficulty 

 in forming his Tables. On an attempt to found them upon the ancient, as well as 

 the modern, observations, it appeared that the theoretical did not agree with the observed 

 course of the planet. He thought this might be attributed to the imperfection of the 

 ancient observations, and consequently rejected all previous to 1781, in the formation of 

 the Tables finally published. These Tables represent well enough the observations in 

 the forty years from 1781 to 1821 ; but very soon after the latter year, new errors 

 began to show themselves, which have gone on increasing to the present time. It 



1 This report, which is headed 'Special Report of view to the discovery of the new planet." This preamble 



Proceedings in the Observatory relative to the new Planet,' is signed by the syndics, H. Philpott (Vice-Chancellor), 



is signed by Challis and dated December 12, 1846. It is John Graham, B. Chapman, W. Whewell, Joshua King, 



preceded by the following introductory remarks. "The Geo. Peacock, James Cartmell, Chas. W. Goodwin, 



syndicate appointed to visit the Observatory, conceiving W. C. Mathison, G. G. Stokes. Professor Challis issued 



the subject at the present time to possess peculiar interest, a second report to the Syndicate, dated March 22, 1847, 



beg leave to submit to the Senate the following statement relating to the subsequent observations of the new 



of Professor Challis, describing the course of observations, planet. This second report was reprinted in the At- 



founded on the theoretical calculations of Mr Adams, of tronomiache Nachrichten (Vol. xxv. col. 309). 

 St John's College, and made at the Observatory with a 



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