xx ii BIOGRAPHICAL NOTICE. 



conclusions had been in the hands of the Astronomer Royal and Challis since 1845, 

 and that the latter had actually been engaged in searching for the planet. There 

 was naturally a disinclination to give full credit to facts thus suddenly brought to light 

 at such a time. It was startling to realise that the Astronomer Royal had had in his 

 possession the data which would have enabled the planet to have been discovered nearly 

 a year before. On the other hand, it seemed extraordinary that a competent mathema- 

 tician, who had determined the orbit of the disturbing planet, should have been content 

 to refrain for so long from making public his results. No time was now lost in bringing 

 the evidence before the world. On November 13, 1846, the Astronomer Royal com- 

 municated to the Royal Astronomical Society an "Account of some Circumstances 

 historically connected with the Discovery of the Planet exterior to Uranus"; and 

 Challis also described the observations which he had undertaken in search of the planet. 

 At the same meeting Adams communicated a memoir containing an account of his 

 mathematical investigations in connexion with the determination of the mass, orbit, 

 and position of the new planet, by which he had obtained the elements communicated 

 to the Astronomer Royal on October 21, 1845, and September 2, 1846. All of these 

 papers are published in Vol. xvi. of the Memoirs of the Society; but as it was felt 

 that the immediate publication of Adams's memoir was a matter of national interest, 

 it was at once printed separately by Lieut. Stratford, superintendent of the Nautical 

 Almanac Office, as a special appendix to the Nautical Almanac for 1851, and widely 

 circulated at the beginning of 1847. This appendix was also issued as a supplement 

 to No. 593 (March 2, 1847) of the Astronomische Nachrichten. 



Having thus given in chronological order an outline of the main facts relating 

 to the discovery of the new planet, it remains to describe in more detail some of the 

 incidents which, apart from their historical interest, are of importance in connexion 

 with the discussions which have taken place on the subject. 



At the time of Adams's first visit to the Royal Observatory, in September, 1845, 

 the Astronomer Royal was abroad. On the occasion of the second visit, on October 21, 

 1845, he was engaged, and was unable to see Adams, who therefore left at the Observatory 

 the paper containing the elements of the planet. Fifteen days afterwards, on November 5, 

 1845, the Astronomer Royal wrote to Adams, " I am very much obliged by the paper 

 of results which you left here a few days since, showing the perturbations on the place 

 of Uranus produced by a planet with certain assumed elements. The latter numbers 

 are all extremely satisfactory: I am not enough acquainted with Flamsteed's observations 

 about 1690 to say whether they bear such an error, but I think it extremely probable. 

 But I should be very glad to know whether this assumed perturbation will explain the 

 error of the radius vector of Uranus. This error is now very considerable, as you will be 

 able to ascertain by comparing the normal equations, given in the Greenwich observations 

 for each year, for the times before opposition with the times after opposition." Un- 

 fortunately Adams did not reply to this enquiry or communicate again with the 

 Astronomer Royal until September 2, 1846, when he forwarded to him the results 

 of his second investigation. 



Le Verrier's memoir of June 1, 1846, reached the Astronomer Royal about the 23rd 

 or 24th of June, and on June 26th the latter addressed to Le Verrier the following letter, 

 containing the same question with respect to the radius vector which he had previously 



