Memoir of the late Francis Baily, Esq., F.R.S., ^r. 49 



dons, which lie at the root of all astronomy, and without which 

 no result can be arrived at, and no practical observer can ad- 

 vance a single step, should have remained up to so late a period 

 as the twentieth year of the nineteenth century, in the loose, 

 irregular, and troublesome state which was actually the case, 

 and t/iat not from their theory being ill understood, but from 

 their practice not having been systematized. Each of the 

 uranographical corrections had to be separately computed by 

 its own peculiar tables, and with coefficients on whose magni- 

 tude no two astronomers agreed. The latter evil, indeed, 

 might be tolerated at a time when the tenth of a second of 

 space was not considered of so much consequence as at pre- 

 sent; but the calculations were formidable and onerous in the 

 extreme to private astronomers, whatever they might be ren- 

 dered in public establishments by habit and the use of auxi- 

 liary tables. So far as the fundamental stars were concerned, 

 the subject had for some time attracted attention, and had begun 

 to receive its proper remedy by the publication, by Professor 

 Schumacher in Denmark, of their apparent places for every 

 tenth day; and by the laudable exertions of Sir James South 

 in our own country, who, for some years, prepared and circu- 

 lated similar tables for every day, not without urgent repre- 

 sentations of the necessity of taking it upas a public concern, 

 which was at length done. But for stars out of this list, 

 except about 500 somewhat facilitated by Zach, there was no 

 provision of any kind, nor any auxiliary tables to have re- 

 course to ; so that sidereal astronomy, beyond the bounds of 

 this favoured list, might be almost said to be interdicted to 

 the private astronomer, owing to the excessive irksomeness of 

 these calculations. This was precisely the sort of case for 

 Mr. Baily to take pity on. He perceived a desert where, 

 with a moderate expenditure of capital, a plentiful harvest 

 might be made to grow, and forthwith proceeded to remedy 

 the evil. Accordingly, with the aid of Mr. Gompertz, he in- 

 vestigated the subject generally, and succeeded in devising a 

 method of arranffinff the terms of the corrections for aberra- 

 tion, solar and lunar precession, adapted to the purpose, and 

 identical in principle with that adopted by M. Bessel, who, on 

 his part, was at the same time, and, actuated by the same mo- 

 tives, engaged on the subject unknown to Mr. Baily. The 

 latter had actually proceeded to the computation of his tables, 

 when the labours of Bessel reached his knowledge, who had, 

 moi-eover, included the precession under the same general 

 mode of expression. Mr. Baily, with characteristic frankness 

 and candour, immediately acknowledged this as an improve- 

 ment in advance of his own idea, and at once adopted and 

 P/iil. Mac;. S. 3. Vol. 26. No. 170. Jan. 1815. E 



