No. 6. Letter of M. Eugene Bouvard to Prof. Airy, Oct. 6, 1837, speaking of 

 the observed anomalies of Uranus, he remarks : 



" Cela tient-il a une perturbation inconnue apportee dans les movements de cat astre par un 

 corps situe au dela? Je ne sais, mais c'est du moins I'idee de mon oncle." 



No. 7. Answer of Prof Airy, Oct. 12: "I cannot conjecture what is the 

 cause of these errors ; but I am inchned, in the first instance, to ascribe them 

 to some error in the perturbations. There is no error in the pure elhptic theory, 

 (as I found by examination some time ago.) If it be the effect of an unseen 

 body, it will be nearly impossible ever to find out its place." 



No. 8. Report of Prof Airy to the British Association. " In 1821, Bouvard 

 published tables of Uranus, (in the same volume with those of Jupiter and 

 Saturn.) With respect to this planet, a singular difliculty occurs. Seventeen 

 observations of Uranus have been found in the observations of Bradley, Mayer, 

 ifec, (for discussions of which, see the Zeitschrift, the Con. des Temps^ &c. ;) 

 and since its discovery as a planet, in 1781, observations have not been wanting 

 in any year. Now, it appears impossible to unite all these observations in one 

 elliptic orbit, and Bouvard, to avoid attributing errors of importance to modern 

 observations, has rejected the ancient ones entii'ely. But even thus the planet's 

 path cannot be represented truly ; for these tables, made only eleven years ago, 

 are now in error nearly half a minute of space." 



No. 9. The detection of some new inequalities in the theory of Uranus, by 

 Hansen. 



No. 10. The researches of Mr. J. C. Adams, first resolved on in 1841, July 3, 

 in consequence of the remark in Prof Airy's Report to the British Association, 

 (No. 8.) They were commenced in earnest in 1843. The inverse problem of 

 perturbations was solved, using the modern places exclusively, which were well 

 represented by assuming a " circular orbit with a distance double that of 

 Uranus" for the unseen disturbing planet. 



No. 11. The proposal of the theory of Uranus as the subject of their mathe- 

 matical prize, by the Royal Academy of Sciences of Gottingen, in 1842. 



No. 12. The resumption of researches by Adams, in 1844, with the addition 

 of the normal or average places from all the observations of Uranus at the 

 Greenwich Observatory, communicated by the Astronomer Royal. The second 



Note to Nos. 3, 4, 5, and 6.— Letter of Rev. T. J. Hussey to Prof. Airy, November 17, 1834, published in the 

 Proceedings of the Royal Astronomical Society for November 13, 1846. See also Astr. Nachr., No. 585. The title of the 

 article is, " Account of some circumstances historically connected with the discovery of the planet exterior to Uranus," by 

 G. B. Airy, Astronomer Royal. 



Note to Nos. 6 and 7. — Airy's Account, &c. 



Note to No. 8. — Proceedings of the British Association for the Advancement of Science, in 1831. 



Note to Nos. 9 and 10. — See Adams' Memoir in the Appendix to the Nautical Almanac for the year 1851. See also 

 letter of Challis to Airy, dated September S2, 1845. Proc. R. A. S., November 13, 1846. 



