Francis Baily, the eminent astronomer, was the third of eight children of Mr. Richard Baily, a banker of Newbury in Berkshire, and Sarah Head, his wife. 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, on 21st October 1796. 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 1850, 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 Native Americans. A matrimonial project was vaguely indicated, in connection with some steps towards naturalization and permanent residence in the United States, but proved abortive and he landed back in Bristol on 1st 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, 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). 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 & 1811) and the treatise itself was translated into French under the auspices of the 'Compognie d'Assurances Generales sur la Vie' (1836). In this country, the demand was such that copies sold for £4 or £5 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.

Baily’s 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' (1813) 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 on 14th March 1811, proved him a skilled computist; but the date assigned, 30th September 610 bc, was shown, by his own appended investigation of the eclipse of Agathocles (15th August 310 bc), to be insecure and was corrected by Sir George Airy, with the aid of improved lunar tables, to 28th May AD 585.

Baily’s interest in astronomical subjects henceforth grew and developed. He wrote a pamphlet, in 1818, summoning attention to the annular eclipse of 7th September 1820, which he himself observed at Kentish Town. In 1819, he translated 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 the words of Sir John Herschel, son of the famous Sir William, "a chief and deciding epoch in his life." He was one of the fourteen who met at the Freemasons' Tavern, on 12th January 1820, and constituted themselves a corporate body with that title. And upon 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 and 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, upon 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 (St. Pancras), 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, he corrected with vast expenditure of time and care; and furnished each with a valuable preface, which were printed in 1843, at his own cost, as volume 13 of the 'Memoirs of the Royal Astronomical Society.' The star catalogue of Tobias Mayer - the publication of which he had procured by the Board of Longitude in 1826 - he revised from the original observations, the result forming part of volume 4 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 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 in Memoirs RAS 4). Baily's historical introduction, preface to the catalogue and appendix (issued in 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 insistence of Baily, by the British Association in 1837-8. In 1842, he had accomplished the arduous task of deducing the mean average from the apparent places of 47,390 stars in the 'Histoire Celeste.' Having seen 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 and so on, 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. 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 1st January 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 on 11th April 1827.

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 1st January 1850) but proper motions, when determinable, were inserted with, in all cases, the secular variation of the annual precessions. 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. 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 a recognisable order the stars composing them. A paper on the subject, read by him before the Royal Astronomical Society on 12th 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, 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 Baily’s zeal. It was rendered inevitable by his strictures on its deficiencies in 1819, 1822 and 1829; and, the admiralty having - upon the death of the superintendent, Dr. Thomas Young, on 10th May 1829 - submitted the matter to the Astronomical Society, Baily formed one of the deliberating committee and drew up the report upon which the National Ephemeris was modelled.

In view of Captain Foster's proposed expedition, Baily devised, in 1828, a simplified kind of convertible pendulum of which two specimens, of iron and copper respectively, formed part of the scientific equipment of the Chanticleer. The accidental death of her commander, on 5th February 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 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 on 31st May 1832. 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, from the Royal Astronomical Society in 1833, authority to construct for them a tubular scale of five feet, 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 on 16th October 1834. A commission of seven, appointed on 11th 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 £500 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. 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, it is due that his memoir (occupying the entire 14th volume of Mem. RAS) "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 anomalies 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 - on 10th February 1843.

The few noteworthy observations of the heavens made by Baily referred, singularly enough, to the subject of his first astronomical investigation. On 15th 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 of 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 excited strong interest and effectively roused astronomers to the importance of eclipses under their physical aspect, that of 8th 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 some instrument (a 3½ foot Dollond's achromatic) used at Inch Hominy. 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". But towards the solution of the magnificent problem, thus presented to science, he did not live to see any advance made.

In June 1841, Francis Baily 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 DCL - 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 on 30th August 1844, aged 70. He was, at the time, President of the Royal Astronomical Society and was buried in his family’s vault in Thatcham Church, near Newbury.

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 Isles 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 a fellow on 22nd February 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.