Adams, John Couch (DNB01)

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ADAMS, JOHN COUCH (1819–1892), astronomer, and discoverer of the planet 'Neptune,' born on 5 June 1819 at Lidcot, near Launceston, Cornwall, was eldest son of Thomas Adams, a tenant farmer, by his wife Tabitha Knill Grylls, the possessor of a small estate. He read at an early age some books on astronomy inherited by his mother, established a sundial on the parlour window-sill, and observed solar altitudes with an instrument constructed by himself out of pasteboard. His education, begun at the village school of Laneast, was continued under his relative, John Couch Grylls, first at Devonport, later at Saltash and Landulph. All his spare time was given to astronomy. He studied the subject in the library of the Mechanics' Institute at Devonport, read Samuel Vince's 'Fluxions,' drew maps of the constellations, and com- puted celestial phenomena. His account of the partial solar eclipse of 15 May 1835, viewed at Stoke 'with a small spyglass,' got into print in the London papers; and after three weeks' watching he caught sight of Halley's comet on 16 Oct. 1835. The development of his genius for mathematics determined his parents to afibrd him a university career, and in October 1839 he entered St. John's College, Cambridge, as a sizar. He graduated in 1843 as senior wrangler and first Smith's prizeman, and became shortly afterwards a fellow and tutor of his college.

At the age of twenty-two Adams, after a thorough study of the irregularities in the motion of the planet Uranus, perceived that they were due to the presence of an exterior planet, the existence of which was not yet recognised. He thereupon formed the design of locating in the sky the undiscovered exterior planet. A memorandum to that effect, dated 3 July 1841, is preserved among his papers, and he had no sooner taken his degree than he attacked the problem. Finding it soluble, he applied, through James Challis [q. v.], to Sir George Biddell Airy [q. V. Suppl.] for complete observational data, and with their aid obtained values for the mass, heliocentric longitude, and elliptic elements of the unseen body. These Adams communicated to Challis in September 1845. A paper embodying the same results, and containing, as Challis said, 'the earliest evidence of the complete solution of an inverse problem of perturbations,' was deposited by Adams at the Royal Observatory, Greenwich, on 21 Oct. 1845, after two fruitless attempts to obtain an interview with Airy. Seven months later, the French astronomer Leverrier announced a conclusion similar to Adams's, and in consequence a search for the missing planet was begun by Challis on 29 July 1840. The new planet, which was christened 'Neptune,' was however, discovered at Berlin by the astronomer Galle on 23 Sept. from Leverrier's indications, Adams's theory remaining undivulged. The first public mention of his name relative to the event was by Sir John Herschel in the 'Athenaeum' of 3 Oct., and a letter from Challis to that journal on 17 Oct. described in detail the transactions between Adams, Airy, and himself. But 'there was naturally a disinclination to give full credit to facts thus suddenly brought to light at such a time. It was startling to realise that the astronomer royal had in his possession the data which would have enabled the planet to be discovered nearly a year before. On the other hand, it seemed extraordinary that a competent mathematician, who had determined the orbit of the disturbing planet, should have been content to refrain for so long from making public his results' (Glaisher, Biographical Notice, p. xxii). Adams himself explained, forty years later, that his reticence was due to his wish that the English astronomers, to whom he imparted his

calculations, might 'look for the planet and find it, so that this country might have had the full credit of the discovery' (private letter). He sent Airy improved elements of the planet on 2 Sept. 1846, and drew up shortly afterwards a paper on the subject for the British Association, but reached Southampton a day too late to present it. Finally, on 13 Nov. 1846, he laid before the Royal Astronomical Society the long-suppressed investigation in which he had determined, from the irregularities of Uranus, the orbit and place of Neptune (Memoirs Royal Astronomical Soc. vol. xvi.). The importance attached to it was signified by its issue as an appendix to the 'Nautical Almanac' for 1861, and as a supplement to No. 693 of the 'Astronomische Nachrichten' (2 March 1847). A French version, with a brief appendix by Adams, appeared in 1876 in Liouville's 'Journal de Mathématiques' (ii. 83).

The publication stirred widespread excitement. A long and bitter controversy ensued. The scientific world split into 'Adamite' and 'anti-Adamite' factions. But their contentions were unshared by the personages to whom they related. Adams's conduct throughout was marked by the utmost dignity and forbearance. He uttered no complaint; he laid no claim to priority ; Leverrier had no warmer admirer. He made personal acquaintance with him at the Oxford meeting of the British Association in June 1847, and both were Sir John Herschel's guests at 'Collingwood in the ensuing month.

Adams refused knighthood in 1847, but the Adams prize, awarded bi-annually for the best essay in astronomy, mathematics, or physics, was founded in 1848, at the university of Cambridge, to commemorate his 'deductive discovery ' of Neptune. He was elected a fellow of the Royal Society on 7 June 1849. He observed the total eclipse of the sun on 28 July 1851 at Frederiksvaern in Sweden (Memoirs Royal Astron. Soc. xxi. 103). Adams was an unsuccessful candidate for the post of superintendent of the 'Nautical Almanac,' vacant by the death of William Samuel Stratford [q. v.] in 1853. His fellowship at St. John's expiring in 1852, he was elected in February 1853 to a fellowship of Pembroke College, which he held until his death. He occupied the chair of mathematics in the university of St. Andrews during the session of 1858-9, vacating it in consequence of his election, late in 1858, to succeed George Peacock [q. v.] as Lowndean professor of astronomy and geometry at Cambridge. His lectures in this capacity were generally on the lunar theory.

Adams's new tables of the lunar parallax, communicated to the Royal Astronomical Society in 1852, were appended to the 'Nautical Almanac' for 1856. In 1853 he presented to the Royal Society a memoir on the secular acceleration of the moon's mean motion, demonstrating the incompleteness of Laplace's explanation of the phenomenon (Phil. Trans, cxliii. 397). This was highly displeasing to French geometers; but the attacks of Plana, Hansen, and Pontecoulant left unshaken conclusions which were independently verified by Delaunay, Cayley, and Sir John William Lubbock [q.v.] Adams replied to objections in the 'Monthly Notices' for April 1860 ; Plana attempted a rejoinder in a series of letters to Sir John Lubbock in June ; and Pont6coulant continued for some time longer to urge threadbare arguments in the 'Comptes Rendus.' An admirable account of the discussion was inserted by Delaunay in the 'Connaissance des Temps' for 1864. Adams refined his methods and improved his results in papers published in the 'Comptes Rendus' for January 1859 and in ' Monthly Notices,' June 1880. The final upshot was to reduce the value for lunar acceleration from 10" to about 6" a century. Other points connected with the lunar theory were treated of by him in separate memoirs presented at intervals to the Royal Astronomical Society.

The Leonid shower of 1866 directed his attention to the movements of those meteors. Laboriously calculating the effects upon them of planetary perturbations, he applied them as a criterion for the determination of their orbit and period (Monthly Notices, xxvii. 247). This, like most of his work, was definitively done. His published writings in pure mathematics were more elegant than extensive, but he enjoyed manipulating long lines of figures, and, having calculated thirty-one 'Bernouillian numbers,' he employed them to obtain the values of 'Euler's constant' to 263 places of decimals. His aid was frequently asked and granted in computations of ancient eclipses and of other astronomical phenomena. He was an assiduous student of Sir Isaac Newton's works, and catalogued with elaborate care the voluminous collection of his manuscripts presented by Lord Portsmouth to the university. He succeeded Challis as director of the Cambridge observatory in 1861, and the acquisition in 1870 of a fine transit-circle by Simms decided him to undertake one of the star-zones assigned for observation to various co-operators by the German Astronomische Gesellschaft. The practical part of the work was done by Mr. Graham, Adams's assistant, and the primary results were published in 1897.

Adams presided over the Royal Astronomical Society for the terms 1851–3 and 1874–6. A testimonial was bestowed upon him by the society in 1848 for his researches into the perturbations of Uranus, and their gold medal in 1866 for his contributions to lunar theory. The Royal Society adjudged him the Copley medal in 1848. Honorary degrees were conferred upon him by the universities of Oxford and Cambridge, of Edinburgh, Dublin, and Bologna. He was a corresponding member of many foreign societies, including the Academies of Paris and St. Petersburg. He declined the office of astronomer royal on Airy's resignation of it in 1881. In 1884 he acted as one of the delegates for Great Britain at the International Meridian Conference of Washington.

He died after a long illness on 21 Jan. 1892, and was buried in St. Giles's cemetery, Cambridge. A portrait medallion of him by Mr. Bruce Joy was in 1895 placed in Westminster Abbey, close to the grave of Newton, and a bust by the same artist was presented by Mrs. Adams to St. John's College. Portraits of him, painted respectively by Mogford in 1851 and by Herkomer in 1888, are in the combination rooms of St. John's and of Pembroke Colleges. A memorial tablet to him was erected in Truro Cathedral on 27 May 1893 (Observatory, xvi. 378), and a bust, executed when he was a young man, stands on the staircase of the Royal Astronomical Society's rooms in Burlington House. A photograph of him, taken by Mrs. Myers four months before his death, was engraved in the 'Observatory' for April 1892.

'Adams was a man of learning as well as a man of science. He was an omnivorous reader, and, his memory being exact and retentive, there were few subjects upon which he was not possessed of accurate information. Botany, geology, history, and divinity, all had their share of his eager attention' (Glaisher). He enjoyed novels, and collected eight hundred volumes of early printed books, which he bequeathed to the University library of Cambridge. Great political questions affected him deeply, and 'in times of public excitement his interest was so intense that he could scarcely work or sleep.' 'His nature was sympathetic and generous, and in few men have the moral and intellectual qualities been more perfectly balanced.' The honours showered upon him. Dr. Donald MacAlister wrote, 'left him as they found him — modest, gentle, and sincere.' He married in 1863 Eliza, daughter of Haliday Bruce of Dublin, who survives him.

The first volume of his 'Scientific Papers' was published in 1896 at the University Press, Cambridge, under the editorship of his youngest brother, Professor William Grylls Adams, F.R.S. A biographical notice by Dr. J. W. L. Glaisher, and a steel engraving by Stodart from a photograph of Adams by Mayall, are prefixed. This volume includes all his published writings. A second volume containing those left in manuscript, so far as they could be made available for publication, appeared in 1901, edited by Prof. W. Grylls Adams and Mr. R. A. Sampson, M.A.

[Memoir by Dr. Glaisher prefixed to Adams's Scientific Papers; Monthly Notices, liii. 184; Observatory, xv. 174; Nature, xxxiv. 565, xlv. 301; Astronomical Journal, No. 254; Grant's History of Physical Astronomy, p. 168; Edinburgh Review, No. 381, p. 72.]

A. M. C.