xxv iii BIOGRAPHICAL NOTICE. 



Astronomer was at dinner; had no message, and therefore went away. But he added 

 that he did not call by appointment. He only took his chance on his way back from 

 Devonshire to Cambridge, &c. &c. I collected that he had been mortified (I am not 

 using his own words) at receiving no message on the second call in October. 'I thought' 

 (said he) 'that though he had been at dinner he would have sent me a message, or 

 perhaps spoken a word or two to me: but I am now convinced that in fact he never 

 knew of my second call that the servant had not delivered my message along with my 

 card.' These were mainly his words. I asked him whether the circumstances just 

 mentioned had any influence in preventing his reply to Professor Airy's note. He said in 

 answer, that had these not happened he possibly might have replied more readily; but 

 assuredly had he considered the question about the radius vector as of great import- 

 ance (' as an experimentum crucis ') he should have answered the note instantly. ' But,' 

 said he, 'I could not look on the corrections of the radius vector as an experimentum 

 crucis; because any hypothesis (however wrong) which gave a correction in longitude 

 must give a correction in the radius vector of the same kind as the correction deduced 

 from the perturbations of the new planet' (I think I state this correctly). 'Again,' said 

 he, 'I wanted to send my papers in good order to the Astronomer Royal. I went over all 

 my calculations thi-ee times. I added a few terms, without changing my results. I was 

 much interrupted, so it was my vacation before I could finish my last revision,' &c. &c. 

 ' I lament very much that I did not immediately answer the first note. I ought to have 

 answered it,' &c. &c. 'But,' he added, 'I did think that the Astronomer Royal would 

 have communicated my results among his correspondents. 1 took all that for granted, 

 and I thought it a publication,' &c. &c. He is anxious to have no misunderstanding 

 with Airy. He spoke very earnestly on this subject, and expressed himself grieved at 

 the ill-natured things that had been said." 



The following letter from Adams to Airy was written five days after the meeting 

 of the Royal Astronomical Society at which Airy's 'Account &c.' was read. 



" ST JOHN'S COLLEGE, 



18 November, 1846. 

 "DEAR SIR, 



"Allow me to thank you for your able, interesting, and impartial 



account of circumstances connected with the discovery of the new planet. I need scarcely 

 say how deeply I regret the neglect of which I was guilty in delaying to reply to the 

 question respecting the radius vector of Uranus, in your note of Nov. 5th, 1845. 



" In palliation, though not in excuse of this neglect, I may say that I was not aware 

 of the importance which you attached to my answer on this point, and I had not the 

 smallest notion that you felt any difficulty on it, such as you subsequently mentioned to 

 M. Le Verrier. 



" For several years past, the observed place of Uranus has been falling rapidly more 

 and more behind its tabular place. In other words, the real angular motion of Uranus is 

 considerably slower than that given by the tables. This appeared to me to show clearly 

 that the tabular radius vector would be considerably increased by any theory which 

 represented the motion in longitudes, for the variation in the second member of the 



equation r" -_.- = J/ja (1-e 2 ) is very small. 



