BIOGRAPHICAL NOTICE. xxiii 



put to Adams: "I have read with very great interest the account of your investigation 

 on the probable place of a planet disturbing the motions of Uranus, which is contained 

 in the Compte Rendu de I'Academie of June 1 ; and I now beg leave to trouble you with 

 the following question. It appears, from all the later observations of Uranus made at 

 Greenwich (which are most completely reduced in the Greenwich observations of each 

 year so as to exhibit the effect of an error either in the tabular heliocentric longitude, 

 or the tabular radius vector), that the tabular radius vector is considerably too small. 

 And I wish to inquire of you whether this would be a consequence of the disturbance 

 produced by an exterior planet, now in the position which you have indicated ? I 

 imagine that it would not be so, because the principal term of the inequality would 

 probably be analogous to the moon's variation, or would depend on sin 2 (v v') ; and in 

 that case the perturbation in radius vector would have the sign - for the present relative 

 position of the planet and Uranus. But this analogy is worth little until it is supported 

 by proper symbolical computations." 



Le Verrier replied to the Astronomer Royal's enquiry on June 28. In this letter he 

 says, "Je compte avoir termini la rectification des e'le'ments de la planete troublante avant 

 1'opposition qui va arriver ; et parvenir a connaitre ainsi les positions du nouvel astre 

 avec une grande precision. Si je pouvais esperer que vous aurez assez de confiance dans 

 mon travail pour chercher cette planete dans le ciel je m'empresserais, Monsieur, de vous 

 envoyer sa position exacte, des que je 1'aurai obtenue." He then explains that the errors 

 in radius vector are well accounted for by the disturbing planet. 



On June 29, before Le Verrier's reply had been received, a meeting of the Board 

 of Visitors of the Royal Observatory took place, at which Sir J. Herschel and Challis, 

 among others, were present. In the course of a discussion the Astronomer Royal referred 

 to the probability of shortly discovering a new planet, giving as his reason the very close 

 coincidence between the results of Adams's and Le Verrier's positions of the supposed 

 disturbing planet. It was in consequence of this opinion that Herschel felt justified in 

 speaking so confidently of the approaching discovery in his address at Southampton on 

 September 10. 



When the planet was discovered at Berlin, the Astronomer Royal was on the con- 

 tinent, and on his return to Greenwich he wrote to Le Verrier, on October 14, 1846 : 

 "I was in Germany at the latter part of the month of September, when I received the 

 intelligence of the actual discovery of the new planet whose place had been so clearly 

 pointed out by you. And I beg you to accept my sincere congratulations on this suc- 

 cessful termination to your vast and skilfully directed labours. Not many days past, I 

 was in company with Professor Schumacher of Altona, and there I had the pleasure of 

 reading the manuscript paper which you have transmitted to him. I was exceedingly 

 struck with the completeness of your investigations. May you enjoy the honours which 

 await you ! and may you undertake other work with the same skill and the same success, 

 and receive from all the enjoyment which you merit ! I do not know whether you are 

 aware that collateral researches had been going on in England, and that they had led to 

 precisely the same result as yours. I think it probable that I shall be called on to give 

 an account of these. If in this I shall give praise to others, I beg that you will not 

 consider it as at all interfering with my acknowledgment of your claims. You are to be 

 recognised beyond doubt as the real predicter of the planet's place. I may add that the 

 A. d 



