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 the greatest benefactors to astronomy. Those of Ptolemy, Ulugh Beigh, Tycho Brahe, Halley, and Hevelius, corrected with vast expenditure of time and care, and furnished each with a valuable preface, were printed in 1843 at his cost as vol. xiii. of the ‘Memoirs of the Royal Astronomical Society.’ That of Tobias Mayer he revised from the original observations, the publication of which by the Board of Longitude he had procured in 1826, the result forming part of vol. iv. of the society's ‘Memoirs,’ and appearing also separately (1830). A comparison of most of its 968 stars with their places as given by Bradley was added, besides forty-five supplementary stars.

The perusal, in 1832, of Flamsteed's autograph letters to his ex-assistant, Abraham Sharp, lent to Baily by his neighbour, Mr. E. Giles, induced him to examine the entire mass of his manuscripts, which had lain mouldering for sixty years in the library at Greenwich. He soon came to the conclusion that Flamsteed's character, both personal and scientific, had been grievously misrepresented, and wrote to the Duke of Sussex, president of the board of visitors of the Royal Observatory, suggesting the propriety of a republication of the ‘British Catalogue,’ with such selections from authentic documents as might serve to rectify prevalent errors in regard to the conduct and motives of its author. The recommendation was adopted, and a massive quarto volume, entitled ‘An Account of the Rev. John Flamsteed, the first Astronomer Royal,’ was issued under Baily's care, at the public expense, in 1835. This remarkable production threw a flood of light on Flamsteed's relations with his contemporaries. It included several autobiographical fragments, forming a tolerably complete whole, a vast mass of previously unpublished correspondence, besides the revised and annotated catalogue, reinforced with Miss Herschel's list of 564 inedited stars from Flamsteed's autograph entries (previously arranged by Baily in order of right ascension, Memoirs Roy. Astron. Soc. iv. 129). Baily's historical introduction, preface to the catalogue, and appendix (issued January 1837) exhibited, in a succinct form, the results of much patient and profound research.

The reduction of the catalogues of Lalande and Lacaille, by which these great stores of celestial information were first rendered practically available, was undertaken, at the instance of Baily, by the British Association in 1837–8. In 1842 he had accomplished the arduous task of deducing the mean from the apparent places of 47,390 stars in the ‘Histoire Céleste.’ In that of seeing both works through the press (the reduction of Lacaille's 9,766 southern stars having been executed by Henderson) he was overtaken by death. Their publication was, after many delays, completed in 1847, the cost of reduction being defrayed by the association, that of printing by the government.

Early in his astronomical career Baily became impressed with the urgent need of a remedy for the prevalent confusion regarding the corrections for aberration, nutation, &c., and had already in 1822, with the aid of Gompertz, devised a means of simplifying their application, when No. 4 of the ‘Astronomische Nachrichten,’ containing Bessel's similar but more comprehensive improvement, was put into his hands (Phil. Mag. ix. 281). Discarding without a murmur his private claims as an inventor, he immediately proceeded to publish and recommend the method by which they had been superseded. This he most effectually accomplished in the ‘Astronomical Society's Catalogue’ of 2,881 stars (epoch 1 Jan. 1830), accompanied by tables for reduction constructed on the new system, forming a boon of inestimable value to practical astronomers. It was printed as an appendix to the second volume of the society's ‘Memoirs’ in 1827. The merit of the compilation can best be estimated by a reference to Sir John Herschel's address in presenting Baily with the Astronomical Society's gold medal, 11 April 1827 (Mem. R. A. S. iii. 123).

The same principles were still further extended in the ‘Catalogue of the British Association.’ Not only the number of stars was increased to 8,377 (reduced to 1 Jan. 1850), but proper motions, when determinable, were inserted, with, in all cases, the secular variation of the annual precessions (see Baily's preface). Resolved upon at the Liverpool meeting of the British Association in 1837, the work was wholly superintended by Baily, and was left by him at his death almost complete. It was published in 1845 at the public cost, and is still in high repute. Owing to the deficiency of reliable materials, however, the places of many of the southern stars included in it were found defective, and were immediately revised by Maclear at the Cape of Good Hope (see, for his list of corrections, Mem. R. A. S. xx. 46). The value of this catalogue, as well as of the two others compiled under the same authority (those of Lalande and Lacaille), was much enhanced by the uniform system of nomenclature adopted throughout. This material improvement was the result of Baily's severe labours in revising the boundaries of the constellations, and marshalling into recog-