"'I send all the results of the observations of _Uranus_ made with both instruments (that is, the heliocentric errors of _Uranus_ in longitude and latitude from 1754 to 1830, for all those days on which there were observations, both of right ascension and of polar distance). No alteration is made in Bouvard's _Tables of Uranus_ except in increasing the two equations which depend on _Jupiter_ by 1/50 part. As constants have been added (in the printed tables) to make the equations positive, and as 1/50 part of the numbers in the tables has been added, 1/50 part of the constants has been subtracted from the final results.' "Professor Challis in acknowledging the receipt of these, used the following expressions:-- No. 8.--PROFESSOR CHALLIS _to_ G. B. AIRY. [_Extract._] "'CAMBRIDGE OBSERVATORY, _Feb. 16, 1844_. "'I am exceedingly obliged by your sending so complete a series of tabular errors of _Uranus_.... The list you have sent will give Mr. Adams the means of carrying on in the most effective manner the inquiry in which he is engaged.' "The next letter shows that Mr. Adams has derived results from these errors. No. 9.--PROFESSOR CHALLIS _to_ G. B. AIRY. "'CAMBRIDGE OBSERVATORY, _Sept. 22, 1845_. "'My friend Mr. Adams (who will probably deliver this note to you) has completed his calculations respecting the perturbation of the orbit of _Uranus_ by a supposed ulterior planet, and has arrived at results which he would be glad to communicate to you personally, if you could spare him a few moments of your valuable time. His calculations are founded on the observations you were so good as to furnish him with some time ago; and from his character as a mathematician, and his practice in calculation, I should consider the deductions from his premises to be made in a trustworthy manner. If he should not have the good fortune to see you at Greenwich, he hopes to be allowed to write to you on this subject.' "On the day on which this letter was dated, I was present at a meeting of the French Institute. I acknowledged it by the following letter:-- NO. 10.--G. B. AIRY _to_ PROFESSOR CHALLIS. "'ROYAL OBSERVATORY, GREENWICH, _1845, Sept. 29_. "'I was, I suppose, on my way from France, when Mr. Adams called here; at all events, I had not reached home, and therefore, to my regret, I have not seen him. Would you mention to Mr. Adams that I am very much interested with the subject of his investigations, and that I should be delighted to hear of them by letter from him?' "On one of the last days of October 1845, Mr. Adams called at the Royal Observatory, Greenwich, in my absence and left the following important paper:-- No. 11.--J. C. ADAMS, Esq., _to_ G. B. AIRY.