Baily, Francis (DNB00)

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BAILY, FRANCIS (1774–1844), an eminent astronomer, was the third son of Mr. Richard Baily, banker, of Newbury, Berkshire, where he was born 28 April 1774. Placed in a London mercantile house at the age of fourteen, the acquaintance of Priestley developed his native taste for experimental inquiries. But though known amongst his young companions as the ‘Philosopher of Newbury,’ love of adventure was as yet stronger in him than love of science, and his seven years' apprenticeship had no sooner expired than he sailed for America 21 Oct. 1795. The narrative of his experiences as a traveller is contained in an extremely curious ‘Journal of a Tour in Unsettled Parts of North America in 1796 and 1797,’ edited by Professor De Morgan in 1856, twelve years after the death of the author. They include two narrow escapes from shipwreck, a voyage in an open boat down the Ohio and Mississippi from Pittsburg to New Orleans, and a return journey to New York across nearly 2,000 miles of ‘wilderness’ uninhabited except by Indians. A matrimonial project, vaguely indicated in connection with some steps towards naturalisation and permanent residence in the United States, proving abortive, he landed at Bristol 1 March 1798, and went home to Newbury. The roving tendency, none the less, was still strong upon him. In May 1799 he volunteered to travel in the service of the African Association, having formed a plan of exploration on the Niger, which, he informed Sir John Stepney, he would have gone through any trials’ to carry out. Funds, however, were deficient; and after some futile thoughts of a commission in the engineers or militia, he accommodated himself to the prosaic destiny of a stockbroker, entering into partnership, about the end of 1799, with Mr. Whitmore, of the London Stock Exchange.

With characteristic thoroughness, Baily now engaged in commercial pursuits. He became a consummate man of business, earning ing, besides a considerable fortune, an unsurpassed reputation for integrity and intelligence. His complete identification with his profession was shown in a pamphlet defending its rights against the encroachments of the city of London in 1806, as well as by the active part taken by him in the exposure of the Berenger fraud in 1814. To his sagacity in preparing the evidence the success of the prosecution was considered to be in great measure, if not wholly, due; and the three reports (printed 1814–15) of the committee appointed by the Stock Exchange to investigate the subject were drawn up by him. A series of remarkable publications meanwhile attested his varied powers. The first of these was entitled ‘Tables for the Purchasing and Renewing of Leases’ (1802, 2nd ed. 1807, 3rd 1812). Its success encouraged him to pursue the subject in two works of standard authority, the ‘Doctrine of Interest and Annuities analytically investigated and explained’ (1808), and the ‘Doctrine of Life-Annuities and Assurances analytically investigated and practically explained’ (1810). The fourteenth chapter of the latter, separately reprinted with the title ‘An Account of the several Life-Assurance Companies established in London, containing a View of their respective Merits and Advantages,’ was greedily bought up in two editions (1810 and 1811), and the treatise itself was translated into French under the auspices of the ‘Compagnie d'Assurances Générales sur la Vie’ (1836). In this country the demand was such that copies sold for 4l. and 5l., and the price of an appendix to the second issue (1813), containing an exposition of Barrett's mode of computing life-tables, alone rose to a guinea. This scarcity induced a fraudulent reprint, succeeded by an avowed republication in 1864 (with omission of the fourteenth chapter and appendix), under the care of Mr. Filipowski. Baily's merits as a writer on life-contingencies were undoubtedly very great. The subject was by him first presented in a symmetrical form; a uniform system of notation was introduced; and to a perspicuous and comprehensive view of the labours of his predecessors the results of much original research were added.

His divergence into a new field was marked by the publication, in 1812, of ‘A New Chart of History,’ accompanied by a ‘Description’—of which five editions were sold in three years—exhibiting the chief revolutions of empire during the historical period. The preparation of chronological tables for an ‘Epitome of Universal History’ (published 1813 in 2 vols. 8vo) led to his first essay in astronomy. A paper ‘On the Solar Eclipse which is said to have been predicted by Thales,’ read before the Royal Society 14 March 1811 (Phil. Trans. ci. 220), proved him a skilled computist; but the date assigned, 30 Sept. 610 B.C., was shown by his own appended investigation of the eclipse of Agathocles (15 Aug. 310 B.C.) to be insecure, and was corrected by Sir George Airy, with the aid of improved lunar tables, to 28 May 585 (Phil. Trans. cxliii. 193; Mem. R.A.S. xxvi. 139).

His interest in astronomical subjects henceforth grew and developed. He wrote a pamphlet in 1818 summoning attention to the annular eclipse of 7 Sept. 1820, which he himself observed at Kentish Town (Mem. R.A.S. i. 135), translated in 1819 Cagnoli's ‘Method of ascertaining the Figure of the Earth by means of Occultations of the Fixed Stars,’ and powerfully helped to quicken astronomical progress in England by his frequent notices, in the ‘Philosophical Magazine,’ of foreign improvements and publications. But the establishment of the Astronomical Society formed, in Sir John Herschel's words, ‘a chief and deciding epoch in his life.’ He was one of the fourteen who met at the Freemasons' Tavern 12 Jan. 1820, and constituted themselves a corporate body with that title. And on Baily, as its acting secretary during the first three years of its existence, devolved the chief labour of its organisation. By him its rules were framed, the routine of its business fixed, its finances set in order. He was a member of every committee, regulated every undertaking, guided every negotiation, drew up nearly every report. By his judicious action the society was, in 1834, put in possession of spacious apartments in Somerset House, and on the death of George IV raised to an equal footing with the Royal Society on the visiting board of the Royal Observatory. He was four times elected its president (for terms of two years), eleven times vice-president, and invariably sat on the council.

In 1825 Baily retired from business, purchased a house and sycamore-shaded garden at 37 Tavistock Place, and devoted himself wholly to astronomy. He was then fifty-one; but in the nineteen years remaining to him he executed labours the extent and value of which it is difficult, in a brief summary, adequately to describe. Although not himself an habitual observer, the scope of his efforts was directed to imparting a higher value to the observations of others, both by connecting them with the past and by assuring them for the future. His revision of star-catalogues alone entitled him, in Sir John Herschel's opinion, to rank amongst 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- nisable order the stars composing them. A paper on the subject, read by him before the Royal Astronomical Society 12 May 1843, was appended to the report of a committee (consisting of Herschel, Whewell, and Baily) appointed by the British Association in 1840 to consider the subject (Report, 1844, p. 34), and was also reprinted in his introduction to the ‘Catalogue.’

The reform of the ‘Nautical Almanac’ was another of the benefits derived by science from his zeal. It was rendered inevitable by his strictures on its deficiencies in 1819, 1822, and 1829, and the admiralty having, on the death of the superintendent, Dr. Thomas Young, 10 May 1829, submitted the matter to the Astronomical Society, Baily formed one of the deliberating committee, and drew up the report upon which the present National Ephemeris was modelled (Mem. R. A. S. iv. 449).

In view of Captain Foster's proposed expedition, Baily devised, in 1828, a simplified kind of convertible pendulum (described in Phil. Mag. iv. 137), of which two specimens, of iron and copper respectively, formed part of the scientific equipment of the Chanticleer. The accidental death of her commander (5 Feb. 1831) threw upon him the onerous duty of digesting and completing (by swinging the pendulums in London) the numerous observations made in both hemispheres; and his elaborate and admirable report, presented to the admiralty and ordered to be printed at the government expense, filled the entire seventh volume of the ‘Royal Astronomical Society's Memoirs.’ The general result of 20,000 experiments gave 1/289.48 for the ellipticity of the earth, showing a most satisfactory agreement with Sabine's of 1/288.40.

Meanwhile Baily had prosecuted independently a research entitling him to a distinguished share of merit in the determination of the length of the seconds' pendulum. Bessel pointed out in 1828 (Abhandlungen Kön. Ak. der Wiss. Berlin, 1826, p. 32) that, in the received ‘correction for buoyancy,’ no allowance was made for the expenditure of force in setting the particles of surrounding air in motion. In order to estimate with precision this neglected element of reduction, Baily had a vacuum-apparatus erected in his house, and there carried out, in 1831–2, a series of most delicate experiments on eighty-six pendulums of every variety of form and material, of which the details were communicated to the Royal Society 31 May 1832 (Phil. Trans. cxxii. 399). It appeared thence that the value of the new correction, while varying very sensibly with the shape and size of the pendulum, was in many cases more than double the old. The subject of the length of the seconds pendulum led naturally to that of the national unit of length, defined by act 5 George IV in terms of that (as it had now proved) uncertain quantity. Baily accordingly obtained in 1833 from the Royal Astronomical Society authority to construct for them a tubular scale of five feet (see his admirable report, Mem. R. A. S. ix. 35), the accuracy of which had been ascertained by repeated comparisons with the standard yard, when the latter was irreparably injured in the conflagration of the houses of parliament 16 Oct. 1834. A commission of seven, appointed 11 May 1838 to consider the best means of replacing it, included him amongst its members; and to him was entrusted in 1843, by the unanimous desire of his colleagues, the actual reconstruction of the standards of length, in the preparatory experiments for which laborious task he was arrested by fatal illness.

The most arduous and conspicuous labour of his life has still to be adverted to. This was the repetition of the ‘Cavendish experiment’ for measuring the density of the earth. The principle of this research depends upon the comparison between the observed attractive effects of masses of ascertained weight and density with the known force of gravity at the earth's surface; but its adequate execution is attended by difficulties of the most baffling description. A remark made by Professor De Morgan at the council-table of the Royal Astronomical Society occasioned the appointment, in 1835, of a committee to consider the matter; but no progress was made until Baily offered his services in 1837, and the treasury granted 500l. towards expenses. The operation, conducted in an upper room of his house, twelve feet square, lasted from October 1838 to May 1842, and resulted in establishing, within narrow limits of error, that our globe is composed of materials, on an average, 5.66 times as heavy as water (Mem. R. A. S. xiv. table vii.) Nevertheless, in spite of precautions incredibly minute, the experiments were vitiated during eighteen months by an unknown cause of error. Ultimate success seemed scarcely to be hoped for, yet Baily resolved to persevere; and to this determination, Lord Wrottesley remarked (Mem. R. A. S. xv. 280), it is due that his memoir (occupying the entire fourteenth volume of Mem. R. A. S.) ‘is hardly less valuable as a lesson upon the nature and use of the torsion pendulum in measuring small forces than as a determination of the mean density of the earth.’ It was at length suggested by Professor Forbes that the anoma- lies in question might be due to the radiation of heat from the leaden masses employed to deflect the pendulum, and proposed gilding both them and the torsion-box. The remedy was completely successful; and the process begun de novo in January 1841 was conducted to a successful issue. The printed observations numbered 2,153 (besides upwards of a thousand rejected as untrustworthy), varying in duration from ten to thirty minutes. This memorable labour was rewarded with the Royal Astronomical Society's gold medal (of which Baily thus for the second time became the recipient) 10 Feb. 1843.

The few noteworthy observations of the heavens made by Baily referred, singularly enough, to the subject of his first astronomical investigation. On 15 May 1836, while watching an annular eclipse of the sun at Inch Bonney, near Jedburgh, he witnessed a phenomenon to which he first directed explicit attention, and which, from his vivid description, received the name of ‘Baily's Beads.’ It consists in the breaking up of the fine solar crescent visible at the beginning and end of central eclipses into a row of lucid points, the intervals separating which at times appear to be drawn out, as the moon advances, into dark lines or belts; the whole being a combined effect of irradiation and the inequalities of the moon's edge. Baily's narrative (Mem. R. A. S. x. 1) excited strong interest, and effectively roused astronomers to the importance of eclipses under their physical aspect, that of 8 July 1842 being at his suggestion prepared for with this view. Baily observed it from an empty room in the university of Pavia, with the same instrument (a 3½-foot Dollond's achromatic) used at Inch Bonney. The ‘beads’ were less conspicuous than before; but he was (in his own words) ‘electrified’ by the unexpected and ‘appalling’ splendour of the corona, through which rose three vast prominences resembling the ‘snowy tops of Alpine mountains when coloured by the rising or the setting sun’ (Mem. R. A. S. xv. 6). But towards the solution of the magnificent problem thus presented to science he did not live to see any advance made.

In June 1841 he was knocked down by a furious rider while crossing Wellington Street, and lay for a week senseless. Nevertheless, he completely recovered, and was able to resume his experiments in weighing the earth by the end of September. It was not until the spring of 1844 that his health, until then remarkably stable, finally gave way, although he rallied sufficiently to attend commemoration at Oxford, when an honorary degree of D.C.L. (previously, in 1835, received from the university of Dublin) was conferred upon him, in company with Airy and Struve. Soon after his return to London, however, an internal complaint became manifest, and he sank gradually and without pain, expiring 30 Aug. 1844, aged 70. He was at the time president of the Royal Astronomical Society.

The abilities of Francis Baily were not of the highest order. As a mathematician his range was a limited one. He never mastered the refinements of modern analysis, and was frequently indebted to the aid of Professors Airy and De Morgan in working out his investigations. Nor was his mind visited by any of the luminous inspirations of genius. Yet his life presents an almost unique example of laborious usefulness to science. More than to any single individual, the rapid general advance of practical astronomy in the British islands was due to him. To clear discernment of the precise wants of his time he joined untiring activity in supplying them. His organising energy was guided by a tact which rendered it irresistible. Add a rare faculty of order and concentration, with a perfect knowledge of and complete mastery over his powers, and the sources of his almost unparalleled effectiveness as a worker become in some degree apparent. Besides the special tasks executed by him with astonishing thoroughness, precision, and rapidity, he took a leading part in the general conduct of scientific affairs. He was unfailing at the annual visitation of the Royal Observatory during twenty-seven years. He succeeded Babbage in 1839 as permanent trustee of the British Association, and had belonged to its council for two years previously. He aided in the foundation (in 1830) and became vice-president of the Geographical Society, acted, during considerable periods, as vice-president and treasurer of the Royal Society, generally held a seat on the council, and rarely missed one of its meetings from the date of his election as fellow, 22 Feb. 1821. Scientific distinctions were showered upon him. He was a fellow of the Linnean and Geological societies, a corresponding member of the Institute of France, of the Academies of Berlin, Naples, and Palermo, and was enrolled on the lists of the American and Royal Irish Academies. Few men have left behind them so enviable a reputation. He was gentle as well as just; he loved and sought truth; he inspired in an equal degree respect and affection. He was never married; and his sister, Miss Elizabeth Baily (who survived him fifteen years), superintended his hospitable establishment.

[Sir J. Herschel, in Memoirs R. Astr. Soc. xv. 311, published separately under the title Memoir of F. Baily, Esq. (1845), also prefixed to the Journal of a Tour, with a list of Baily's writings, ninety-one in number; Month. Not. R. Astr. Soc. xiv. 112; Abstracts Phil. Trans. v. 524; Peacock's Address Brit. Ass. 1844, xxxix.; Dublin Review, xviii. 75 (De Morgan on Repetition of Cavendish Experiments).]

A. M. C.