His most famous achievement was predicting the existence and position ofNeptune, using only mathematics. The calculations were made to explain discrepancies withUranus'sorbit and thelaws ofKepler andNewton. At the same time, but unknown to each other, the same calculations were made byUrbain Le Verrier. Le Verrier sent his co-ordinates to Berlin Observatory astronomerJohann Gottfried Galle, who confirmed the existence of theplanet on 23 September 1846, finding it within 1° of Le Verrier's predicted location. (There was, and to some extent still is, some controversy over the apportionment of credit for the discovery; seeDiscovery of Neptune.) Later, Adams explained the origin ofmeteor showers, which holds to the present day.[2]
Adams was born at Lidcot, a farm atLaneast,[1] nearLaunceston, Cornwall, the eldest of seven children. His parents were Thomas Adams (1788–1859), a poortenant farmer, and his wife, Tabitha Knill Grylls (1796–1866). The family were devoutWesleyans who enjoyed music and among John's brothers, Thomas became a missionary, George a farmer, andWilliam Grylls Adams, professor ofnatural philosophy andastronomy atKing's College London. Tabitha was a farmer's daughter but had received a rudimentary education from John Couch, her uncle, whose small library she had inherited. John was intrigued by the astronomy books from an early age.[3]
John attended the Laneast village school where he acquired someGreek andalgebra. From there, he went, at the age of twelve, toDevonport, where his mother's cousin, the Rev. John Couch Grylls, kept a private school.[1] There he learnedclassics but was largely self-taught inmathematics, studying in the Library ofDevonport Mechanics' Institute and readingRees's Cyclopædia andSamuel Vince'sFluxions. He observedHalley's Comet in 1835 fromLandulph and the following year started to make his own astronomical calculations, predictions and observations, engaging in private tutoring to finance his activities.[3]
In 1821,Alexis Bouvard had published astronomical tables of theorbit ofUranus, making predictions of future positions based onNewton's laws of motion andgravitation.[5] Subsequent observations revealed substantial deviations from the tables, leading Bouvard to hypothesise some perturbing body.[6] Adams learnt of the irregularities while still an undergraduate and became convinced of the "perturbation" theory. Adams believed, in the face of anything that had been attempted before, that he could use the observed data on Uranus, and utilising nothing more than Newton's law of gravitation, deduce themass, position and orbit of the perturbing body. On 3 July 1841, he noted his intention to work on the problem.[3]
After hisfinal examinations in 1843, Adams was electedfellow of his college and spent the summer vacation in Cornwall calculating the first of six iterations. While he worked on the problem back in Cambridge, he tutored undergraduates, sending money home to educate his brothers, and even taught his bed maker to read.[3]
Apparently, Adams communicated his work toJames Challis, director of theCambridge Observatory, in mid-September 1845, but there is some controversy as to how. On 21 October 1845, Adams, returning from a Cornwall vacation, without appointment, twice called onAstronomer RoyalGeorge Biddell Airy inGreenwich. Failing to find him at home, Adams reputedly left a manuscript of his solution, again without the detailed calculations. Airy responded with a letter to Adams asking for some clarification.[7] It appears that Adams did not regard the question as "trivial", as is often alleged, but he failed to complete a response. Various theories have been discussed as to Adams's failure to reply, such as his general nervousness, procrastination and disorganisation.[7]
Meanwhile,Urbain Le Verrier, on 10 November 1845, presented to theAcadémie des sciences in Paris a memoir on Uranus, showing that the preexisting theory failed to account for its motion.[1] On reading Le Verrier's memoir, Airy was struck by the coincidence and initiated a desperate race for English priority in discovery of the planet.[8] The search was begun by a laborious method on 29 July.[3] Only after the discovery of Neptune on 23 September 1846 had been announced in Paris did it become apparent that Neptune had been observed on 8 and 12 August but because Challis lacked an up-to-date star-map it was not recognized as a planet.[1]
A keen controversy arose in France and England as to the merits of the two astronomers. As the facts became known, there was wide recognition that the two astronomers had independently solved the problem of Uranus, and each was ascribed equal importance.[1][3] However, there have been subsequent assertions that "The Brits Stole Neptune" and that Adams's British contemporaries retrospectively ascribed him more credit than he was due.[7] But it is also notable (and not included in some of the foregoing discussion references) that Adams himself publicly acknowledged Le Verrier's priority and credit (not forgetting to mention the role of Galle) in the paper that he gave 'On the Perturbations of Uranus' to the Royal Astronomical Society in November 1846:[9]
I mention these dates merely to show that my results were arrived at independently, and previously to the publication of those of M. Le Verrier, and not with the intention of interfering with his just claims to the honours of the discovery; for there is no doubt that his researches were first published to the world, and led to the actual discovery of the planet by Dr. Galle, so that the facts stated above cannot detract, in the slightest degree, from the credit due to M. Le Verrier.
Adams held no bitterness towards Challis or Airy[3] and acknowledged his own failure to convince the astronomical world:[7]
I could not expect however that practical astronomers, who were already fully occupied with important labours, would feel as much confidence in the results of my investigations, as I myself did.
His lay fellowship at St John's College came to an end in 1852, and the existing statutes did not permit his re-election. However,Pembroke College, which possessed greater freedom, elected him in the following year to a lay fellowship which he held for the rest of his life.Despite the fame of his work on Neptune, Adams also did much important work on gravitational astronomy and terrestrial magnetism.[1] He was particularly adept at fine numerical calculations, often making substantial revisions to the contributions of his predecessors. However, he was "extraordinarily uncompetitive, reluctant to publish imperfect work to stimulate debate or claim priority, averse to correspondence about it, and forgetful in practical matters".[3] It has been suggested that these aresymptoms ofAsperger syndrome which would also be consistent with the "repetitive behaviours and restricted interests" necessary to perform the Neptune calculations, in addition to his difficulties in personal interaction with Challis and Airy.[10]
He had hoped that this work would leverage him into the vacant post as superintendent ofHM Nautical Almanac Office butJohn Russell Hind was preferred, Adams lacking the necessary ability as an organiser and administrator.[3]
Since ancient times, theMoon's mean rate of motion relative to the stars had been treated as being constant, but in 1695,Edmond Halley had suggested that this mean rate was gradually increasing.[11] Later, during the eighteenth century,Richard Dunthorne estimated the rate as +10" (arcseconds/century2) in terms of the resulting difference in lunar longitude,[12] an effect that became known as thesecular acceleration of the Moon.Pierre-Simon Laplace had given anexplanation in 1787 in terms of changes in theeccentricity of the Earth's orbit. He considered only the radial gravitational force on the Moon from theSun and Earth but obtained close agreement with the historical record of observations.[13]
In 1820, at the insistence of theAcadémie des sciences, Damoiseau, Plana andFrancesco Carlini revisited Laplace's work, investigatingquadratic and higher-order perturbing terms, and obtained similar results, again addressing only a radial, and neglecting tangential, gravitational force on the Moon. Hansen obtained similar results in 1842 and 1847.[14]
In 1853, Adams published a paper[15] showing that, while tangential terms vanish in the first-order theory of Laplace, they become substantial when quadratic terms are admitted. Small termsintegrated in time come to have large effects and Adams concluded that Plana had overestimated the secular acceleration by approximately 1.66" per century.[14]
At first, Le Verrier rejected Adams's results.[16] In 1856, Plana admitted Adams's conclusions, claiming to have revised his own analysis and arrived at the same results. However, he soon recanted, publishing a third result different both from Adams's and Plana's own earlier work. Delaunay in 1859 calculated the fourth-order term and duplicated Adams's result leading Adams to publish his own calculations for the fifth, sixth and seventh-order terms. Adams now calculated that only 5.7" of the observed 11" was accounted for by gravitational effects.[14] Later that year, Philippe Gustave Doulcet, Comte de Pontécoulant published a claim that the tangential force could have no effect thoughPeter Andreas Hansen, who seems to have cast himself in the role ofarbitrator, declared that theburden of proof rested on Pontécoulant, while lamenting the need to discover a further effect to account for the balance. Much of the controversy centred around theconvergence of thepower series expansion used and, in 1860, Adams duplicated his results without using a power series. SirJohn Lubbock also duplicated Adams's results and Plana finally concurred. Adams's view was ultimately accepted and further developed, winning him theGold Medal of the Royal Astronomical Society in 1866.[1][14][16] The unexplained drift is now known to be due totidal acceleration.[3]
In 1858 Adams became professor of mathematics in theUniversity of St Andrews, but lectured only for a session, before returning to Cambridge to take up the Lowndean professorship of astronomy and geometry. Two years later he succeeded Challis as director of theCambridge Observatory, a post Adams held until his death.[1]
The greatmeteor shower of November 1866 turned his attention to theLeonids, whose probable path and period had already been discussed and predicted byHubert Anson Newton in 1864.[1] Newton had asserted that thelongitude of the ascending node, that marked where the shower would occur, was increasing and the problem of explaining this variation attracted some of Europe's leading astronomers.[3]
Using a powerful and elaborate analysis, Adams ascertained that this cluster of meteors, which belongs to theSolar System, traverses an elongated ellipse in 33.25 years, and is subject to definite perturbations from the larger planets, Jupiter, Saturn, and Uranus. These results were published in 1867.[1] Some experts consider this Adams's most substantial achievement.[17] His "definitive orbit" for the Leonids coincided with that of thecomet55P/Tempel-Tuttle and thereby suggested the, later widely accepted, close relationship between comets and meteors.[3]
Ten years later,George William Hill described a novel and elegant method for attacking the problem of lunar motion. Adams briefly announced his own unpublished work in the same field, which, following a parallel course had confirmed and supplemented Hill's.[1]
Over a period of forty years, he periodically addressed the determination of the constants inCarl Friedrich Gauss's theory ofterrestrial magnetism. Again, the calculations involved great labour, and were not published during his lifetime. They were edited by his brother,William Grylls Adams, and appear in the second volume of the collectedScientific Papers. Numerical computation of this kind might almost be described as his pastime.[1] He calculated theEuler–Mascheroni constant, perhaps somewhat eccentrically, to 236decimal places[3] and evaluated theBernoulli numbers up to the 62nd.[1]
Adams had boundless admiration for Newton and his writings and many of his papers bear the cast of Newton's thought.[1] In 1872,Isaac Newton Wallop, 5th Earl of Portsmouth, donated his private collection of Newton's papers toCambridge University. Adams andG. G. Stokes took on the task of arranging the material, publishing a catalogue in 1888.[18][19]
The post ofAstronomer Royal was offered him in 1881, but he preferred to pursue his teaching and research in Cambridge. He was British delegate to theInternational Meridian Conference atWashington in 1884, when he also attended the meetings of the British Association atMontreal and of the American Association atPhiladelphia.[1]
1847 He is reputed to have been offered a knighthood onQueen Victoria's 1847 Cambridge visit but to have declined, either out of modesty, or fear of the financial consequences of such social distinction;[3]
After a long illness, Adams died at Cambridge on 21 January 1892 and was buried near his home in St Giles Cemetery, now theParish of the Ascension Burial Ground in Cambridge.[21] In 1863 he married Miss Eliza Bruce (1827–1919), ofDublin, who survived him and is buried with him.[1] His wealth at death was £32,434 (£2.6 million at 2003 prices).[3][22]
Airy, G. B. (1847). "Account of some circumstances historically connected with the discovery of the planet exterior to Uranus".Memoirs of the Royal Astronomical Society.16:385–414.Bibcode:1847MmRAS..16..385A.
Moore, P. (1996).The Planet Neptune: An Historical Survey before Voyager. Praxis.
Sampson, R.A. (1904). "A description of Adams's manuscripts on the perturbations of Uranus".Memoirs of the Royal Astronomical Society.54:143–161.Bibcode:1904MmRAS..54..143S.
Adams, J.C., ed. W.G. Adams &R. A. Sampson (1896–1900)The Scientific Papers of John Couch Adams, 2 vols, London: Cambridge University Press, with a memoir byJ.W.L. Glaisher:
A collection, virtually complete, of Adams's papers regarding the discovery of Neptune was presented by Mrs Adams to the library of St John's College, see: Sampson (1904), and also:
"The collected papers of Prof. Adams",Journal of the British Astronomical Association,7 (1896–97)
Monthly Notices of the Royal Astronomical Society,53 184;
The papers were ultimately lodged with the Royal Greenwich Observatory and evacuated toHerstmonceux Castle during World War II. After the war, they were stolen byOlin J. Eggen and only recovered in 1998, hampering much historical research in the subject.[27]
^abcdSheehan, W.; Kollerstrom, Nicholas; Waff, Craig B. (December 2004). "The Case of the Pilfered Planet – Did the British steal Neptune?".Scientific American.291 (6):92–99.doi:10.1038/scientificamerican1204-92.PMID15597985.
^Adams, J.C. (1846)."On the Perturbations of Uranus".Appendices to various nautical almanacs between the years 1834 and 1854 (reprints published 1851) (note that this is a 50Mb download of the pdf scan of the nineteenth-century printed book). UK Nautical Almanac Office. p. 265. Retrieved23 January 2008.
^Sheehan, W.; Thurber, S. (2007). "John Couch Adams's Asperger syndrome and the British non-discovery of Neptune".Notes and Records of the Royal Society.61 (3):285–299.doi:10.1098/rsnr.2007.0187.S2CID146702903.
^Halley, Edmond (1695)."Some Account of the Ancient State of the City of Palmyra, with remarks on the Inscriptions found there".Philos. Trans. R. Soc.218:160–175.doi:10.1098/rstl.1695.0023.JSTOR102291.S2CID186214936. Also Philos. Trans. R. Soc. (Abridgements) vol. 4 (1694–1702) pp. 60 at 65: Halley concluded his 1695 article on middle-eastern antiquities by writing: "And if any curious traveller ... would please to observe, with due care, the phases of the moon's eclipses at Bagdat, Aleppo and Alexandria, thereby to determine their longitudes, they could not do the science of astronomy a greater service: for in and near these places were made all the observations by which the mean motions of the sun and moon are limited: and I could then pronounce in what proportion the moon's motion does accelerate; which that it does, I think I can demonstrate." But it was left toRichard Dunthorne actually to make the first quantitative assessment of the Moon's apparent acceleration.
^Adams, J.C. (1853). "On the secular variation of the Moon's mean motion".Philosophical Transactions of the Royal Society of London.143:397–406.doi:10.1098/rstl.1853.0017.S2CID186213591.
^A Catalogue of the Portsmouth Collection of Books and Papers written by or belonging toSir Isaac Newton, the Scientific Part of which has been Presented by the Earl of Portsmouth to the University of Cambridge, drawn up by the Syndicate appointed 6 November 1982, Cambridge: Cambridge University Press, 1888
^Kollerstrom, N. (2001)."Eggen takes the papers".The British Case for Co-prediction. University College London. Archived fromthe original on 6 February 2005. Retrieved23 August 2007.
