Royal Society Publishing

John Couch Adams's Asperger syndrome and the British non-discovery of Neptune

William Sheehan , Steven Thurber

Abstract

We discuss the mathematical acumen of John Couch Adams together with cognitive and behavioural characteristics that suggest Asperger syndrome. We also review the historical events involved in the investigation of the unknown planet thought to be affecting the orbital motion of Uranus. Adams produced a vital computation necessary for the discovery of Neptune that was insufficient unless integrated with specialized knowledge of other members of a British ‘team’ and then presented formally to the scientific community. Reasoning from the premise that complex scientific discoveries often involve cooperative social dynamics, we conclude that Adams was precluded from sharing his contribution in a collaborative manner, in part, because of empathic and social communication deficiencies related to his disorder. However, it was a ‘team’ failure, not Adams's alone.

Introduction

The discovery of Neptune is one of the most celebrated events in the history of astronomy. The planet's existence and position in the sky had been worked out mathematically even before it was recognized in a telescope. The basic elements of the story are too well known to need repeating here.1 Two mathematical astronomers, John Couch Adams of England and Urbain Jean Joseph Le Verrier of France, investigated why the planet Uranus seemed to be straying off its predicted course after its discovery in 1781. They hypothesized that it was being pulled by an unknown planet, and worked out its position.

Adams completed his calculations first, and in the autumn of 1845 he submitted a thumbnail of his results (without any indications of the theory used to obtain them) on a small undated piece of paper to James Challis, director of the Cambridge University Observatory. He later made a similar ‘publication’ of them to George Biddell Airy, the Astronomer Royal at Greenwich. However, neither acted on what had been communicated to them until Le Verrier published a compatible position in the following June, at which point Airy drew up plans for a search to be implemented by Challis. According to the standard story, Challis proceeded, but so halfheartedly and inefficiently that in the end the optical discovery of the planet was made not in England but in Berlin, by Johann Galle and Heinrich d'Arrest, acting on Le Verrier's instructions, on 23 September 1846. There ensued an international furore after the British scientific establishment pushed Adams's name forward as a co-claimant in the discovery. His unpublished calculations were later cited as the basis for his being credited as the ‘first theoretical discoverer’ and even (in Sir David Brewster's words) as ‘first discoverer’ of Neptune.2 However, Adams's hold on that vaunted position was purchased at the expense of sacrificing the reputations of Challis and Airy; the latter, in particular, was savaged to the extent that Neptune ‘seemed unduly to overshadow him for the rest of his life.’3

Such is the standard story, culled from various accounts, chiefly Airy's to the Royal Astronomical Society on 13 November 1846 and the reactions to it; it has been repeated so often as to have become canonical.

The most confounding problem with the standard version is how to explain—without characterizing Challis as a hopelessly inept bumbler and Airy as an unimaginative bureaucratic prig—the seven or eight months' delay from Adams's unsolicited communication of the results (though not the theory) of his investigation to Challis and Airy in the autumn of 1845 and the publication of Le Verrier's paper (in the French Academy's journal Comptes Rendus) the following June, which finally triggered the surreptitious British search for the planet. Related to it is the problem of explaining why, even after the search was launched, it proved to be so draggy and unsuccessful.

With Challis and especially Airy traditionally cast in the role of villains (‘O curse their narcotic souls!’ exclaimed Adam Sedgwick, geologist at Cambridge's Trinity College, and close friend of Airy, when the word got out after the stunning announcement in Berlin), Adams has been portrayed as a wronged innocent—an incontestably brilliant mathematician in the mould of Isaac Newton, but ‘shy and retired’, lacking personal force, inexperienced in the ways of the world and unable to make more than a faint impression on his more obtuse colleagues. We argue that this is a gross oversimplification. Instead of being a victim who was merely ‘unfortunate in the two astronomers to whom he communicated his results who failed to give to a young and retiring man the kind of help or advice that he should have received’,4 Adams emerges as a rather complex and even paradoxical individual, whose intellectual astuteness was offset by equal measures of social-skills deficiencies, a tendency to procrastinate and tinker even when the situation called for action, and an almost pathological difficulty in writing prose narrative, a near-fatal combination that made him seem adrift, indecisive and mute at the very moments when conviction and clear indications of what his investigations had uncovered were needed. We suggest that the most likely explanation of this is that Adams probably had Asperger syndrome or autistic spectrum disorder (ASD), a condition common among mathematicians and physicists at the highest levels of achievement, which severely hampered his ability to navigate the social world of Victorian science.5 Core symptoms of autism include difficulties in social relationships and communication skills, strong narrow interests, and repetitive behaviours. Individuals at various levels on the autism dimension will evince these core symptoms with varying degrees of severity. In addition, at one extreme on the spectrum are persons with below-average intelligence, language delays and learning problems. In contrast, at the opposite end of the autism dimension are individuals classified with Asperger syndrome, associated with average to superior intelligence, essentially normal language development and with an absence of learning difficulties. At this upper end of the continuum, there is a propensity for the development of cognitive structures that facilitate understanding of the physical world but with a mental lacuna regarding an understanding of the world of social interactions and relationships.6,7 The search for the planet was a complicated undertaking that required not only high-level mathematical analysis such as that performed by Adams but also what might be called the other ‘super-extended phenotypes’8 of a professional observer and a strong administrator—in other words, what was needed was a multi-specialty team, by definition a social structure and a collaborative entity.

John Couch Adams

An extraordinary mathematician when he arrived at St John's College, Cambridge, from Cornwall, Adams would be remembered (in his obituary in The Observatory, April 1892) as England's ‘greatest mathematical astronomer Newton alone excepted’.

In fact, Adams's career closely paralleled that of nearby Trinity's famous son, Isaac Newton, who has also been plausibly identified as having had ASD. Both shared bucolic backgrounds and the open spaces of the English countryside, Newton having grown up as an illiterate yeoman's son at Woolsthorpe, near Grantham in Lincolnshire, and Adams at Lidcot, a farm on the edge of Laneast Down, a bleak upland moor seven miles from the town of Launceston in Cornwall. (Of the two, Adams's surroundings were rather more rolling, lush and picturesque.) Both demonstrated a marked preference for books over farm work—they drove pegs or cut notches in window ledges or walls to mark the motion of the Sun—and were interested from an early age in the regularities of mathematics and natural phenomena (as a teenager, Adams calculated local times for a solar eclipse in Cornwall, a non-trivial task in those days before electronic calculators and computers; local legend has it that he ‘observed the heavens while leaning against an ancient Celtic cross near the family home’,9 just as Newton ‘lay under a hedge studying whilst the man went to town and did the business’.)

By the age of 10 years, Adams had developed such an extraordinary talent in mathematics that a family acquaintance considered him a ‘prodigy’ and told Adams's father, ‘If he was my boy, I would sell my hat off my head rather than not send him to college.’10 Even so, his family might not have been able to afford the expense of sending him to Cambridge had it not been for the timely intervention of a small inheritance his mother received from an aunt and the discovery on the family farm of a lode of manganese. Manganese was an additive used in the steel-making process to harden metal, and the profits derived from it helped him and his siblings to escape the dreary and depressing fate of most nineteenth-century rustics.

As soon as Adams arrived at St John's in 1839, his savant-like abilities stood out, and it was clear to at least one of his colleagues that he was a different order of being when it came to mathematics. ‘I was in despair,’ A. S. Campbell recalled after having a long talk with Adams on the subject, ‘for I had gone up to Cambridge with high hopes and now the first man I meet is something infinitely beyond me.’11 Campbell was right; Adams went on to take all the prizes in mathematics that the university could offer, including Senior Wrangler (in the prestigious Cambridge Mathematics Tripos, a position Airy and Challis had both held) and First Smith's Prizeman. His ability to work things out in his head is attested to by his approach to the problem papers in his Tripos Examination, where ‘when everyone was working hard, Adams spent the first hour in looking over the questions, scarcely putting pen to paper the while. After that he wrote out rapidly the problems he had already solved “in his head”.’12 He ended up earning more than twice as many points as his nearest competitor.

Like many Victorian-era students, Adams enjoyed long walks, often in company with others. On one occasion he and two companions walked all the way from Cambridge to London. He was superficially sociable, playing at bowls on the college lawns and card games in the college rooms (he was better at Vingt-et-un than whist). More exceptionally, late in life he relaxed from a stupefyingly complex analysis of the Moon's motions by calculating 31 Bernoullian numbers, in addition to the 31 previously known, which he then applied to a calculation of Euler's constant to 273 places of decimals.13

Although Adams seems to have been universally regarded as a gentle, harmless soul, his personal diaries from the late 1830s and early 1840s show little personality. These diaries are exasperatingly short on personal revelation and seldom rise above the level of providing simple listings of events. They are bland ledgers of objectivities such as meeting places or the intersection of his personal coordinates with those of other people who might just as well have been smooth round billiard-balls as persons (at no point does he demonstrate that he possessed anything of what psychologists Baron-Cohen, Leslie and Frith have described as ‘theory of mind’)14. The following excerpts from his diary of 1839 (in the St John's College Library) are typical:

June 12. Walked with Mr. Martin part of the way to North Brent, then returned and went by way of Chip Shop and Mill Hill to Tavistock where I took tea, at Kingston's. His two uncles are on a visit there; 15 h. Got up early, took breakfast at Kingston's and walked with him, according to previous agreement to the mouth of the Tunnel where we got into the foremast of the Iron boats, were conveyed through it. This Tunnel is about 1 3/4 miles long, cut almost all the way through solid rock: the date inscribed at either end is 1803.15

Such entries are mixed up with expressions of guilt about missing chapel or renewed determination to be more diligent in rooting out ‘evil passions and habits’. In his case, the most anxiety-producing was a tendency to indolence—he upbraids himself repeatedly for a persistent failure to make the best use of his time.

Among such unpromising fare appears the following entry of 3 July 1841. Wandering through the St John's College bookstore, he discovered Airy's 1832 ‘Report on the Progress of Astronomy’ mentioning Uranus's increasing deviation from the path predicted for it. He jotted the following memorandum:

Formed a design … of investigating, as soon as possible, after taking my degree, the irregularities of the motion of Uranus, which are not yet accounted for, in order to find whether they may be attributed to the action of an undiscovered planet beyond it.

The attraction of such a problem to someone like Adams, with his enjoyment in manipulating long lines of figures, was obvious. Literary critic George Steiner has written of the uncanny ability of savants, even child-masters (though Adams was 22 years old at the time), to achieve works of genius in mathematics and music that are in vital respects dynamic acts of location. Symbolic counters are arranged in significant rows. Solutions, be they of a discord, of an algebraic equation or of a positional impasse, are achieved by a regrouping, by a sequential reordering of individual units and unit-clusters (notes, integers, rooks or pawns). The child-master, like his adult counterpart, is able to visualize in an instantaneous yet preternaturally confident way how the thing should look several moves hence. He sees the logical, the necessary harmonic and melodic argument as it arises out of an initial key relation or the preliminary fragments of a theme.16

These were, of course, just the abilities needed by a master-mathematician in pursuit of a secretive planet. However, the individuals who excel in these areas have, as Steiner goes on to say, mental energies and capacities that are often wholly isolated, ‘as if they explode to ripeness apart from, and in no necessary relation to, normally maturing cerebral and physical traits’; abilities localized to some part of the brain—splendidly or tragically, as the case may be—isolated from other mental and physiological capabilities.

There has never been any doubt of Adams's ability as a mathematician. He had, at least when he was in the vein for it, immense powers of concentration. He had the characteristic ability of individuals with ASD, ‘to immerse themselves in subjects for long periods, a total involvement with a subject that is very difficult for many people without Asperger syndrome. The great strength of mathematical geniuses and persons with Asperger syndrome is their ability to focus and exclude unnecessary inputs.’17

Although the difficulty in switching attention easily can be of value, it does make multi-tasking a challenge, and in Adams's case this probably accounts for his tendency (discussed below) to do his original researches on the Uranus problem only during vacations, when he was (relatively) less subscribed with other responsibilities such as tutoring and conducting examinations. His need to focus single-mindedly on a problem to the exclusion of all else or not to do it at all did lead to long hiatuses in the prosecution of that work.

‘He scarcely ever destroyed anything he wrote, or performed rough calculations’, notes Glaisher; ‘the manuscripts that he has left are written so carefully and clearly that it is difficult to believe that they are not finished work that has been copied out fairly’.18 Inevitably, this finished quality of his work, regarded as a virtue among mathematicians, seems to have made it difficult for him (much less others) to retrace his thought processes. But this too is characteristic of ASD, where the tendency to present ‘finished productions’ failing to show the theories behind a solution speaks to an inability to take account of another's perspective. Adams failed to recognize that things obvious to him (even if they were obvious only after much thought) were not obvious to others; he did not acknowledge that theory contributes to the proof.

Other mathematicians have shown similar characteristics. E. T. Bell has written of Gauss, who recorded in simple brief statements the outcomes of elaborate researches in his scientific diary (Notizenjournal) in partial mitigation of his slowness to publication:

He declared that such an overwhelming horde of new ideas stormed his mind before he was twenty that he could hardly control them and had time to record but a small fraction. The diary contains only the final brief statements of the outcome of elaborate investigations, some of which occupied him for weeks. Contemplating as a youth the close, unbreakable chains of synthetic proofs in which Archimedes and Newton had tamed their inspirations, Gauss resolved to follow their great example and leave after him only finished works of art, severely perfect, to which nothing could be added and from which nothing could be taken away without disfiguring the whole. The work itself must stand forth, complete, simple, and convincing, with no trace remaining of the labor by which it had been achieved.19

Newton, in the Principia, also disguises his tracks. He could never have reached his results through the deductive method of Euclidean geometry in which he recasts them but only through immense powers of visualizing objects moving in space. Though Pope could write, ‘ “Let Newton be!” And all was light’, Newton's manuscripts reveal his struggles; his working papers might well be compared to the messy drafts that Beethoven produced in writing one of his symphonies. At the end of his effort, with all traces of the creative process—and all intellectual debts to others—obliterated, he emerges with a tour de force of complicated geometrical diagrams, which partake of ‘the closed perfection of that forever removed out of time’.20 According to Glaisher, Adams was like these other masters:

Based on his later performance, there can be no doubt that Adams constantly allowed himself to postpone the immediate publication of his researches, with the intention of effecting improvements in the processes and mode of representing the subject, or of attaining to an even more accurate result. … [But] no able mathematician who is engaged upon a fruitful research can continually defer publication with impunity: the subject opens before him; his views expand; the earlier results, so interesting at the moment of discovery, lose their charm in comparison with the problems still unsolved and the novel vistas of thought opened out by them; and the rearrangement and rewriting of the old work—always an irksome task—become intolerable when later and still unfinished developments on the same subject are exciting the mind.21

The ‘shy and modest genius was a “loner”, especially where mathematics was concerned; his private calculations transported him into other worlds, where he made himself entirely at home. … Some of his academic Cambridge contemporaries recognized a similar mind as had been sighted in Newton previously.’22 Again: ‘Adams had the greatest possible admiration for Newton. … His mind bore naturally a great resemblance to Newton's in many marked respects, and he was so penetrated with Newton's style of thought that he was peculiarly fitted to be his interpreter.’23 One thinks not only of the Newton of Wordsworth's fine tribute in the Prelude,

with his prism and silent face,The marble index of a mind foreverVoyaging through strange Seas of Thought, alone,but of his first biographer Stukeley's account:

On going home from Grantham, ’tis usual at the town end to lead a horse up Spittlegate hill, being very steep. Sir Isaac has been so intent in his meditations, that he never thought of remounting, at the top of the hill, and so has led his horse home all the way, being 5 miles. And once, they say, going home in this contemplative way, the horse by chance slipt his bridle and went home: but Sir Isaac walked on with the bridle in his hand, never missing the horse.24

The powers of the human brain seem, in a way, to reflect a zero-sum game. The extraordinary powers of a Newton, a Gauss or an Adams are purchased (it may even be are necessarily purchased) through monstrous inequities of structure.25 The brain has long been known to have a modular structure, and it seems that the extravagant, if sometimes highly selective, abilities of autistic savants may be accounted for by the activity of certain brain modules unrestricted and unimpeded by interference with others that, although useless to the sublime work of genius, are difficult to dispense with in the realm of the everyday. This phenomenon has been referred to as ‘paradoxical functional facilitation’.26 Although individuals with ASD may have extraordinary abilities in visual–spatial organization and mechanical arithmetic, in which the right hemisphere is thought to be superior to the left,27 in other respects, and rather paradoxically, they resemble individuals with right-hemisphere damage or nonverbal learning disability. Patients with right-hemisphere damage show behaviour that is often associated with the brilliant young mathematician or computer scientist. This highly rational individual is ever alert to an inconsistency in what is being said, always seeking to formulate ideas in the most airtight way; but in neither case does he display any humour about his own situation, nor the many subtle intuitive interpersonal facets that form so central a part of being human. One feels rather that the answers are being typed out at high speed on computer printout paper.28 They may thus combine right-hemispheric assets—the visual–spatial abilities, arithmetic skills and non-verbal hearing (music)—with right-hemisphere deficits characteristic of individuals with social–emotional learning disability.29

Apart from his ability to juggle figures in his head, Adams seems to have been a notoriously faint and forgettable personality. He suffered from a speech impediment.30 As a member of a musical family, he did ‘inherit a correct ear and a love of music’.31 He had difficulty in multi-tasking (as noted, a key symptom of ASD), which prevented him from pushing forward on more than one front simultaneously and probably accounts for why, with the exception of a few calculations at the end of 1845, he seems to have completely abandoned the Uranus project until the mid-summer of 1846. He had an extreme difficulty in expressing himself in clear and ordinary—narrative—prose. If, as Samuel Johnson once said, ‘a man is accustomed to compose slowly and with difficulty upon all occasions, there is danger that he may not compose at all, as we do not like to do that which is not done easily.’ Challis later explained to Airy (19 December 1846) that Adams was ‘extremely tardy about writing. … He experiences also a difficulty, which all young writers feel more or less, in putting into shape and order, what he has done, and well done, so as to convey an adequate idea of it to others by writing.’ All young writers may experience some such difficulty, ‘more or less’; however, for Adams it may reflect something more: the tendency to think in visual images rather than words, thus making ordinary language a second language into which his own thoughts had to be laboriously translated. Something similar is attested to by Einstein, who wrote to the psychologist Jacques Hadamard of his own thought process:

The words or the language, as they are written or spoken, do not seem to play any role in my mechanism of thought. The physical entities which seem to serve as elements in thought are certain signs and more or less clear images which can be voluntarily reproduced and combined. Conventional words or other signs have to be sought for laboriously only in a secondary stage.32

This difficulty with prose—especially narrative, which is almost entirely lacking in Adams's writings—may also reflect his inability to imagine things from another's perspective.33

Adams was an inveterate tinkerer, a perfectionist, who would spare no pains when it came to his calculations and who strove for completeness but could ‘publish’ the most momentous of his results to senior colleagues on small scraps of paper without date, leaving them to guess at the theory behind them (which in the event they failed to do until after the fact). As noted, the combination of outstanding mathematical abilities and a failure to grasp the way in which the world wagged socially is typical of individuals with ASD.

Adams's calculations

Adams did not get around to the problem of Uranus until after his graduation in 1843. In this case his delay may have been, but was not necessarily, a manifestation of the usual tendency to procrastination for which he often castigated himself; it could well have been a simple consequence of his other undergraduate preoccupations and perhaps a need to develop his mathematical skills further. It may also, of course, attest to his difficulty in multi-tasking.

When he did get around to his Uranus calculations, he was a fellow still in residence at St John's. By then the problem of Uranus's straying motion had been tackled—and dropped—by the German astronomer Friedrich Wilhelm Bessel, who had already achieved astronomical immortality for his achievement in measuring the first distance to a ‘fixed’ star, 61 Cygni. In fact, Adams was completely unaware of this, and in splendid isolation he believed he had the field to himself for the next two years.

When at last he began to unfold his strategy, he sought through an intermediary—the Rev. James Challis, director of the Cambridge University Observatory about a mile's walk (uphill) from St John's—further observational data on Uranus's positions as observed at the Royal Greenwich Observatory. Challis (on 13 February 1844) requested the data from Airy on behalf of his ‘young friend’, and Airy graciously supplied it by return of post (on 15 February 1844).

Adams's plan was to test whether the hypothesis of an unknown planet would correct the straying values of Uranus's motion. As a first approximation, he assumed that the planet's distance would accord with Bode's law, a curious empirical relationship that had worked well for all the known major planets and for the four known minor planets (the fifth, Astraea, would be added just at the end of 1845). Bode's law put the planet at a mean distance of about 38 astronomical units, twice Uranus's distance. Busy with tutoring and performing his other ‘important duties’ at the college, Adams concentrated his energies on the Uranus problems mainly during his vacations in Cornwall. His brother George later recalled:

On those occasions dear Mother, who would be exhausted with her heavy work, before going to bed would prepare the milk and bread for us for supper before retiring. This I should warm when required and we take together. … Often have I been tired, and said, ‘It's time to go to bed, John.’ His reply would be, ‘In a minute,’ and go on almost unconscious of anything but his calculations. In his walks on those occasions on Laneast Down, often with me, his mind would be fully occupied in his work. I might call his attention to some object, and get a reply, but he would again relapse into his calculations.34

George Adams certainly paints a vivid picture of John Couch Adams, self-absorbed in his calculations, walking across the bleak Laneast Down. He is the very image of the abstracted and disengaged mathematician, like Isaac Newton who, as noted earlier, became absorbed in thought and dreamily walked his horse on the road home from Grantham. The tendency to become so absorbed in work that nothing else disturbs him (even such basic needs as hunger) is a feature of ASD. An additional document attesting to Adams's ASD characteristics consists of a series of reminiscences of an anonymous student signing himself ‘Peregrine’, published in the year after Adams's death. ‘Peregrine’ did not know Adams well himself; he remembered him only as ‘a rather small man, who walked quickly, and wore a faded coat of green’. But he made inquiries from which he produced a convincing portrait:

Oddly enough, I had lodgings in my last term which Adams, somewhat my senior, had inhabited long before; I think in his last term but one. [The landlady] said that she sometimes found him lying on the sofa, with neither books nor papers near him; but not infrequently he was standing at a desk he had fixed against the wall, and that when she wanted to speak to him the only way to attract his attention, was to go up to him and tap him on the shoulder; calling to him was of no use. I found out afterward that the great man was in the habit, after he had accomplished a certain piece of work at the desk, of thinking the whole matter out on the sofa, and it was there, probably, that his brain-work was at the greatest.35

By mid-September of 1845, Adams communicated that he had arrived at ‘results’ to Challis. There is some uncertainty as to the nature of this communication, although it has been plausibly identified with a small piece of paper without date identified among Adams's papers by Ralph Sampson only in 1901 (‘rec'd in Sept. 1845’ has been added in another's, presumably Challis's, handwriting). If this was indeed the critical communication, it contains a predicted mean longitude of the planet at 321° 30′ ‘nearly’ (for a date given only as ‘at end of Sept.’). This position would have been accurate to within 3°, less than the width of Ursa Major's bowl, of where the actual planet was lurking at the time; given the planet's prominence as an eighth-magnitude object, this position might have been good enough to have turned up the planet even if Adams himself had chased it with the St John's College Observatory's rather primitive instruments, as he later told Airy he considered doing (to Airy, 18 November 1846):

Of the accuracy of my calculations I was quite sure, from the care with which they were made, and the number of times I had examined them. The only point which appeared to admit of any doubt was the assumption as to the mean distance, and this I soon proceeded to correct. 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 investigation as I myself did; and therefore I had our instruments put in order, with the express purpose, if no one else took up the subject, of undertaking the search for the planet myself, with the small means afforded by our observatory at St. John's.36

Although this was Adams's later account, he surmised correctly that no practical astronomer would have been interested in the problem at this stage, especially since he had made no effort to acquaint any of them with the theory behind his calculations. Challis himself, who was always busy and much-harassed, later explained his own indifference at the time:

No one could have anticipated that the place of the unknown body was indicated with any degree of exactness by a theory of this kind. It might reasonably be supposed, without at all mistrusting the evidence which the theory gave of the existence of the planet, that its position was determined but roughly, and that a search for it must necessarily be long and laborious. This was the view I took, and consequently I had no thought of commencing the search in 1845.37

At least Challis was not dismissive. He dutifully wrote to Airy, the acknowledged British expert on the Uranus problem, informing him that Adams, his ‘friend’, had ‘arrived at results, which he would be glad to communicate to you personally’. Adams's next move again attests to the ignorance of social custom of someone with ASD. At a time when Cambridge was, as it would be long afterward, stiff and formal with protocol—as a later student at St John's from one of the colonies said, ‘men call on one another and leave cards, instead of just running in whenever you want to see a fellow’38—Adams decided to drop by, unannounced, at the Astronomer Royal's residence during his next vacation, on his way home to Cornwall. Airy was the busiest civil servant in the land. The first time that Adams called, Airy was away in France; his wife, Richarda, who was home alone, later had no recollection of Adams's visit. Adams again called at Airy's residence, twice, on 21 October 1845, when he was on the way back from Cornwall to Cambridge; during the second try of the day Airy was at dinner and was not informed of Adams's call. What Adams could not have known was that he called at a time when Airy was dealing not only with his usual enormous workload but tending to Richarda in the latter stages of pregnancy and dealing with the scandalous murder-case involving a former assistant. Moreover, Airy's routine, which he kept zealously, required him to dine at half past 3 every afternoon (astronomers’ hours are often unusual!). Although there is no evidence that Airy was ever informed of the unannounced visit, Adams left feeling discouraged. A rumour would later circulate around St John's in the aftermath of the discovery of Neptune that Airy had failed to give the ‘young and retiring man’ advice and help at a critical moment (he had ‘snubbed him’). Adams himself does not seem to have encouraged such views. He did, however, tell Sedgwick (Sedgwick to Mrs Airy, 6 December 1846):

He did not call by appointment. He only took his chance I thought (said he) that though he had been at dinner he would have sent me a message on the second call in October. ‘I thought,’ (said he) ‘though he had been at dinner he would have sent me a message, or perhaps spoken a word or two to me.’

As Adams left he dropped through Airy's letter-box a brief summary of his results including, among other orbital elements, a predicted mean longitude of 323° 34′ for the hypothetical disturbing planet on 1 October 1845. It is notable that the documents Adams is supposed to have deposited with Challis and Airy, which ought to be the ‘crown jewels’ of the whole controversy and to form the basis of the later British claims for Adams's priority, hardly seem worthy of the name. As uncertain even to its identity as the Challis document is, the Airy document is equally unimposing. The date ‘October 1845’ has been inscribed at the top in a different hand, presumably Airy's. The exact date of Adams's visit, 21 October, has had to be determined from remarks that Adams made in a letter to his parents. Adams's set of elements can be regarded neither as self-contained nor as self-explanatory. Their significance would not possibly have been apparent without knowing details of the theory upon which they were based, except to someone clairvoyant. No details are given of the theory used to produce its set of ‘error-values’ between observations and positions predicted by perturbation equations based on assumed elements of the planet.

Although Adams's summary was hardly a ‘publication’ in any orthodox sense of the word, Airy, to his credit, did try to follow up. He wrote a letter (5 November 1845) that would become one of several key documents that would come to haunt the whole affair. Airy says in part:

I am very much obliged by the paper of results which you left here a few days since, shewing the perturbations on the place of Uranus produced by a planet with certain assumed elements. … I should be very glad to know whether this assumed perturbation will [also] explain the radius vector of Uranus.

Airy was alluding to the fact, which he himself had determined through an extensive series of observations in the 1830s, that Uranus, in addition to being adrift in longitude, was slightly farther from the Sun than it ought to be. Had Adams responded to Airy's query, Airy might have launched a search then and there and the British might have had the discovery of Neptune to themselves. But Adams did not send a reply. For Airy, the non-response was decisive. ‘I did not even urge Challis to observe, because (in consequence of Adams not having answered to my critical question) I regarded the whole matter as doubtful.’39 There it was: game, set, and match.

The reason for Adams's non-response has always seemed a bit of a mystery. Challis was the first to furnish the diagnosis of writer's block to account for Adams's inaction:

I believe that nothing but procrastination was the reason of his not sending an answer at all. I have always found him more ready to communicate orally than by writing. It will hardly be believed that before I began my observations I had seen nothing of his in writing respecting the New Planet, except the elements which he gave me in September written on a small piece of paper without date. … The public would hardly take such a reason as that I have mentioned to be the true reason for his not answering your question, and I fear, a hiatus must remain in the History.40

Adams himself later told Airy (18 November 1846):

I need scarcely say how deeply I regret the neglect of which I was guilty in delaying to reply to the question respecting the radius vector of Uranus. In palliation, though not in excuse of this neglect, I may say that I was not aware of the importance which you attached to my answer on this point, and I had not the smallest notion that you felt any difficulty on it.

Adams's explanation is revealing; for why, if Airy attached no importance to the matter, would he have written to Adams about it at all? On various occasions, Adams stated that he considered Airy's inquiry ‘trivial’—the correction of the radius vector seemed obvious to him. He thought that ‘the whole matter might be better explained by half an hour's conversation than by several letters, in writing which I have always experienced a strange difficulty.’41 He is speaking through his ASD. He told Sedgwick, as reported by the latter to Richarda Airy:

had he considered the question about the radius vector as of great importance (‘as an experimentum crucis’) he should have answered instantly. But, said he, I could not look on the corrections of the radius vector as an experimentum crucis; because any hypothesis (however wrong) which gave a correction in Longitude must give a correction in the radius vector of the same kind as the correction deduced from the perturbations of the New Planet.42

The lack of reciprocation reflected in Adams's failure to respond to Airy's letter shows a failure to navigate the social world—after all, he had so far communicated to Airy only in monologue form, and Airy was seeking to establish a dialogue; Adams failed to enter into it. From Airy's perspective, this made further communication impossible:

I waited with much anxiety for Mr. Adams's answer. Had it been in the affirmative, I should at once have exerted all the influence which I might possess, either directly or indirectly through my friend Professor Challis, to procure the publication of Mr. Adams's theory.

Drawing on the clinical literature on ASD, we argue that Adams had been posed a version of what has been described as the ‘false-belief test’. This test, developed by Wimmer and Permer,43 has been applied by Baron-Cohen and others to demonstrate the ‘mind-blindness’ associated with individuals with Asperger syndrome, their inability to represent others’ mental representations or what Baron-Cohen refers to as ‘meta-representation of mental states’.44 In this test, a puppet puts a marble in Box A, then exits. The second puppet comes onstage, finds the marble in Box A, puts it in Box B and leaves. Now the first puppet returns. The question is: Where will he look for the marble? Children more than four years old will usually say ‘in Box A, because that is where the puppet thinks it is.’ Asperger children, on the other hand, expect the puppet to look in Box B, because that's where it actually is. Adams believed that he knew the answer to the radius vector problem—what it actually was—but failed to grasp that communicating his ideas to Airy required him to take account of what Airy might think it to be. (In fact, Airy regarded it as the experimentum crucis; this was, in fact, Airy's own phrase.) Adams was unable to construct a meta-representation of Airy's mental state. Although Adams began an abortive letter to Airy soon afterwards, he never finished it,45 and did not again attempt to communicate with Airy until 2 September 1846—and by then it was far too late.

A retrospective view of the British non-discovery of Neptune

We note that, in contrast with most heroic achievements in science before the discovery of Neptune, the mathematical and optical investigations that led to the discovery were simply too complicated, required too diverse and too specialized skills, to be accomplished altogether by any one individual. What was required was something kindred to the complex multi-modal processing of a brain in which the computations of each lobe had somehow to be organized into resolution, action-plan and execution. There was the solution of the inverse problem of perturbations itself, which required someone possessed, like Adams, of a magnificent parietal lobe; the optical survey, which needed the participation of a skilful (and motivated) practical astronomer (in the event, the reluctant Challis was thrust into that role); and a strong executive able to organize these efforts into a concerted, timely, and forceful action (that would be Airy). (One might, of course, apply this model to the Franco-German team that actually succeeded in discovering the planet as well.)

Thus, rather than being the singular endeavour of any one person, no matter how gifted, the search for the unseen but felt disturber of Uranus required what we are now quite used to seeing in science but which was somewhat unfamiliar in early Victorian times—a team effort. Unfortunately, most historians who have written about the discovery of Neptune have continued to apply inappropriate categories that emphasize Adams's contribution or Le Verrier's alone.

A more useful way of viewing these events would be to apply the now familiar paradigm of rival research teams competing to be first past the post in achieving an important result, in which case we can see that the Franco-German team, consisting of LeVerrier, Arago, Encke, Galle and d'Arrest, beat the British (Cambridge) team of Adams, Airy and Challis.

This would put some perspective on the bitter priority disputes that generated more heat than light because they pursued the answer to the wrong question.

If the search for Neptune was indeed a project requiring the collaboration of multiple specialists in a coordinated team effort, then it becomes obvious that a prerequisite for its success included at least minimal social skills—the ability of the participants to engage in a socially organized activity, to communicate with one another (which implies some ability to take another's point of view) so as to coordinate their activities in an efficient and effective way. Robert W. Smith has discussed, pertinently, the importance of the ‘Cambridge network’ to the British search for the planet.46 To the extent that the Cambridge network—the affiliation of scientists who pledged allegiance to the ‘old school tie’—was invoked shows not a secretive conspiracy as sometimes suggested but the acknowledgement of the potential utility of a pre-existent social structure as opposed to the invention of a new one. In terms of our analogy to the brain, this was to use white-matter connections already formed between different grey-matter nuclei or lobes rather than to attempt to lay down fresh tracts for myelination. The problem with the British strategy was not its reliance on a Cambridge network (as later alleged by outsiders such as the would-be planet seeker, the capable but non-Cantabrigiensian astronomer John Russell Hind). In that it existed, the Cambridge network was an advantage. The problem was, we believe, that the key participant, John Couch Adams—in part because of the very specialization of his own brain for complex mathematical computations—suffered from ASD, and had marked limitations in areas of ‘theory of mind’ and an inability to navigate the social world successfully.

Thus, instead of parietal (visuo-spatial computational), occipital (visual) and prefrontal (executive) functions yoked together to a common purpose, the ‘collective brain’ of the Cambridge network remained disconnected and inefficient. No individual should, however, be singled out for blame; the failure was the failure of the team. (Traditional accounts have, of course, sacrificed Airy and Challis on the altar of Adams, who is thereby exalted to the status of an unappreciated Cambridge mathematical hero, an early Victorian equivalent of Newton.) But in fact it was Adams who was the critical if blameless failure—the faulty O-ring47 to the whole structure—as a result of his being possessed of a remarkably specialized and savant-like ability whose very possession, we have argued, effectively precluded him from the equally indispensable share of the social-navigational and executive skills that would have made it possible for him to communicate his results in an effective, forceful and timely fashion to his would-be collaborators.

The post-discovery disarray that engulfed Airy and Challis was largely the result of their suddenly if retrospectively acquiring a panoramic view of a situation of which they had previously been allowed only fugitive and tantalizing glimpses through the keyhole of Adams's own narrowly focused ASD perceptions.

    Notes

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