J. Brit. Astron. Assoc., 106, 4, 1996
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by Richard Baum
With the discovery of an eighth magnitude object near Delta Capricorni on 1846 September 23, J. G. Galle and H. d'Arrest at Berlin successfully concluded the search for Neptune, then the farthest known planet from the Sun. The event was promptly acclaimed, and designated one of the greatest triumphs of celestial mechanics. News reached England on September 30. Next day J. R. Hind announced the discovery in a letter to the London Times where it was avidly read by the owner of the largest telescope in England, William Lassell (1799–1880), the wealthy Liverpool brewer.[1]
That same day Sir John Herschel scribbled a note to Lassell urging him to look for 'satellites with all possible expedition!!'[2] The letter arrived at Starfield, Lassell's Liverpool home the following day, October 2; that night he logged his first observation of Neptune. Within days he had made two extraordinary observations. On the 3rd, he thought the planet encircled by a ring, and on the 10th he had his first glimpse of its principal moon, Triton.[3] But these were trifles compared to what Edward S. Holden, director of the Lick Observatory, disclosed in 1892.[4]
In 1876 Holden spent several months in England. He travelled widely and struck up many friendships. He was particularly taken by Lassell with whom he had previously corresponded, and visited the family home at Maidenhead, a large property called Ray Lodge. As a result of this intimacy he became privy to a family secret; a circumstance first disclosed to him by Mrs Lassell, but later confirmed and explained in greater detail by Lassell himself. Lassell however, had no intention of publicly divulging it 'during the lifetime of Professor Adams' in case it revived bad memories of a painful episode in his life. As it happened John Couch Adams outlived Lassell by twelve years, dying in 1892.
Two years earlier, in anticipation of that event, Holden had resurrected the secret and had been in touch with Jane Lassell, Lassell's second eldest daughter. Writing from Mount Hamilton on 1890 May 9, he remarked, 'I remember very well, when I was once at your house, being told by Mrs Lassell & afterwards by your father, the very strange history of how Neptune was not searched for at Starfield. How Dawes had written from Greenwich to Mr.Lassell, who was then confined to a sofa by a strained ankle, & how the letter was lost, through the carelessness of a maid-servant – & how finally, the search was not made. This conversation interested me greatly, partly because of its relation to the history of Astronomy & partly because of the delicate solicitude of your father lest some notice of this should come to Professor Adams & perhaps add a regret to his feeling regarding the discovery. Its interest to Astronomy seems to me to lie in various points. It is certain for example that if your father had searched for Neptune with the splendid two-foot reflector, that he would have recognized it at once by its disc. – Again if he had found it, the whole merit of the discovery would have gone to England, for this was a year or so before Le Verrier's announcement. Thus the official life of Le Verrier (& the developement of Astronomy in France) would have been greatly influenced. This accident of a maid-servant's carelessness has then really affected the developement of the astronomy of a nation ... I thoroughly appreciate the delicate feeling of your father that this should never be known to Professor Adams.'[5] Holden then asked if Miss Lassell would prepare an account of 'the circumstances in a form that could be printed,' and if she would entrust the manuscript to him for use when appropriate. He gave assurance not to publish while Professor Adams was alive, but felt the story should sometime be 'told as a part of a strange history – one of the strangest in astronomical history.'[6]
Jane Lassell responded on June 9: 'Your letter of the 9th of May last correctly states the incident you refer to, whereby the honour of the discovery of Neptune was lost to England. I can hardly add anything to your graphic account, in fact it had escaped my memory that my Father had wished the matter to remain dormant till Professor Adams' death. ... I think such a statement as you have yourself written to me would answer every purpose in the interests of science – it is correct and can have our sanction.'[7]
Holden did not have long to wait. John Couch Adams died on 1892 January 21. Nine days later the following story was released. 'It is known that in October 1845, Professor Adams, then an undergraduate of Cambridge submitted to Sir George Airy, Astronomer Royal, the results of his computations on the perturbations of Uranus and the elements of a new planet – Neptune – which would account for the observed disturbances in the orbit of the former.' About this time the Rev. W. R. Dawes, the well known double star observer, chanced to visit Greenwich 'and the letters and computations of Adams were shown to him by Airy.' Unlike the latter, Dawes was very impressed and 'at once wrote to Lassell to beg him to search for Neptune, in the region designated by Adams, with his powerful two-foot reflecting telescope (which was then mounted at Starfield, near Liverpool).' When the letter arrived 'Lassell was confined to his sofa by a sprained ankle' and unable to observe. He thus had it placed on his writing table, but once he was improved 'the letter could not be found as it, together with some other papers, had been removed and destroyed by a too zealous maid-servant.' I think, Holden continued, 'though I am not sure, that renewed inquiry was made by Lassell of Dawes as to the data in question. However this may have been, they were never recovered, and the mistaken zeal of the maid-servant had its full effect.' Holden concluded his recollection by emphasizing 'the delicate consideration of Mr. Lassell,' who kept all this secret 'in order that no possible shade of regret should be inspired during the lifetime of Professor Adams.'[8]
The story, which is basically an oral tradition, a tribal incident perpetuated by hearsay and memory, has been cited by many writers, including Morton Grosser, author of the standard work on the discovery,[9] and is now an integral part of the mythology that has grown up around the dramatic events of 1846. As told it has the ring of authenticity. Adams did call at Greenwich in October 1845. We also know Lassell was indisposed, which makes the 'mislaid letter' aspect all the more plausible. Or does it? That Lassell could have discovered Neptune is beyond doubt. Whether in fact he had the opportunity to do so before September 23 as he claimed, is quite another matter.
Lassell was a compulsive observer who relished every opportunity to demonstrate the excellence of his telescopes. By late 1845 he was the proud owner of a 24-inch Newtonian built with the assistance of James Nasmyth, inventor of the steam hammer, and owner of the Bridgewater foundry at Patricroft, near Manchester. One only has to skim through Lassell's observing diaries for 1845 and 1846 to sense the pride he felt in his achievement. What better chance then of showing off its capabilities than a search for, and possible discovery of, the long rumoured exterior planet? What a triumph all round if it should be found! Yet Lassell's records are strangely mute of such excitement. His correspondence offers no contradiction – not even the merest trace of regret or grievance. After investigating the incident in 1982 Robert W. Smith, Hubble Space historian, came to the conclusion that the story as told to Holden is unreliable and misleading,[10] and in a subsequent paper he adduced further evidence in support of his contention.[11]
Of course there may be some truth in Lassell's recall of Dawes' visit to Greenwich in October 1845. It is well known Adams left a brief summary of his findings for Airy at Greenwich on the 21st, giving the orbital elements and mean longitude of Neptune for 1845 October 1. Yet Dawes' extant papers give no indication he knew of these results prior to October 1846. Curiously in 1890 Jane Lassell recollected 'that the calculation had been wholly made by Mr Dawes – but possibly he got some data from Professor Adams.' She did admit however, 'we were very young at the time and the matter has been considerably one of hearsay to us.'[12]
Perhaps the most telling piece of evidence is in Smith, 'The Cambridge Network in Action: The Discovery of Neptune'.[13] During 1846 Lassell corresponded about his Saturn observations with Sir John Herschel. Herschel knew of the search at Cambridge, yet neglected to mention it, nor did he so much as hint at the probable existence of an exterior planet. In August though he could not contain himself, as William Rowan Hamilton, Astronomer Royal of Ireland at Dunsink Observatory, and professor of astronomy at Trinity College, Dublin, reported to a correspondent some two months later: 'I may mention that, when I was lately [in August 1846] a guest of Sir John Herschel at Collingwood, we took a drive together to visit Mr. Dawes, an amateur of astronomy, who has erected a private observatory, with some excellent instruments, in that neighborhood, during which visit the conversation turned on the theoretical announcement of the new planet by Le Verrier. It was not generally supposed that the stranger would show himself till about Christmas; but Sir John Herschel recommended Mr. Dawes to begin looking for him at once.'[14] Dawes apparently did not react to the suggestion, but Smith queries if this incident might be the source of Lassell's discomfiture. Obviously without documentary evidence this can only be speculation. So doubts remain. However with the discovery of an overlooked statement by Albert Marth, one time assistant to Lassell, it is possible even they can now be finally laid to rest.
At the monthly meeting of the British Astronomical Association held in Barnard's Inn Hall, Holborn, 1892 June 29, Captain William Noble presiding, visual study of Mars and the Milky Way was high on the programme. In the course of the discussion Marth made some interesting remarks about Lassell and his observations of Mars. Before resuming his seat, he requested time to correct a story 'which had grown out of a partly misunderstood statement. Prof. Holden, of the Lick Observatory, had recently given ... of Lassell's failure to discover the planet Neptune, derived from what he had been told in 1876 by Mrs. Lassell, but which he had refrained from making known till after Prof. Adams's death.'
According to Marth: 'There had been ... no need for it to have been hushed up till then. Prof. Adams was perfectly well acquainted with the story, as the speaker [Marth] had learnt in the course of a confidential consultation three years ago [1889], before the last council meeting of the Royal Astronomical Society which Adams attended, Dawes having told it to him some 40 years before.' Marth himself first heard the story in 1876 from Mrs Lassell, several weeks before Holden's visit. Though he could not learn the full date, he understood it was in September 1846, only a couple of weeks before the actual discovery of Neptune, when Dawes wrote to Lassell 'urging him to point the 24-inch reflector to a certain part of the heavens and look for a star with a disk.'[15]
A reconciliation of fact and hearsay now seems possible, especially if Dawes did inform Lassell of John Herschel's imperative. For on 1846 September 7, Lassell wrote to Herschel, regretting his indisposition and temporary absence from home, but hoped to be back at Starfield in three or four days. In the event he was, and observing with the 24-inch on September 11, 12, 14, 15 and 16.16 Neptune was discovered on the 23rd, but this was not known to Lassell until October 1. Lassell and Dawes were very close friends, and in regular correspondence; it is known, for instance, that in February 1846 Lassell stayed at Cranbrook, Kent, about 40 miles southeast of London, where Dawes had settled in a country house not far from Sir John Herschel. So if Lassell had lost the positional data, presuming it had been sent, he had only to ask for it to be replaced.
As already mentioned Lassell observed Neptune for the first time on 1846 October 2. His entry is surprisingly stark; but it appears the planet was found quickly and easily by its disk. Did he perhaps then realise a lost opportunity with regret, a feeling that in memory influenced his recollections and converted them into the tale he subsequently told Holden? After all at the age of 77, relying solely on memory, he was recalling events that took place thirty years earlier when he was 47.
Although the truth may never be known, by his intimations of Adams and Dawes, Marth does at least edge the story away from family oral tradition, coincidentally to invest it with a little more credibility. Now the emphasis is on Dawes who by implication is cited as having full knowledge of the incident. This places him more centrally, and focuses our attention on his meeting with Herschel in August 1846, and the indisposition of Lassell early in September – two key elements in the original story. Importantly, according to Marth Dawes informed Adams sometime around 1852 when the incident was still comparatively fresh in mind. Hence if there is any truth in it we are left with an uncomfortable thought – how is it no search was mounted for Neptune from Starfield in September 1846? There are of course many valid reasons, enough to keep the door open on a fascinating mystery in the life of one of the big names in the history of astronomy.
I should like to thank Dorothy Schaumberg, Mary Lea Shane Archives of the Lick Observatory for all her help in the preparation of this notice, and for permission to quote from the letters of Edward Holden and Jane Lassell. Dr Robert W. Smith is thanked for early stimulating discussions on this and closely associated matters.
Richard Baum
25 Whitchurch Road, Great Boughton, Chester CH3 5QA
To be published in the Journal of the British Astronomical Association, August 1996.
Copyright 1996, Richard M. Baum and the British Astronomical Association