Adams, Airy and the Discovery of Neptune in 1846
by Allan Chapman
Soon after Neptune was discovered in Berlin, in September 1846, using Le
Verrier's Computed position, a furore broke out in Britain about the
priority of John Couch Adams. Though Adams's claim had not been advanced
until October 1846, when even the English astronomers were still speaking of "Le
Verrier's Planet", it came to be realised that Adams had already
arrived at a computed position for the Uranus-disturbing planet by
the autumn of 1845. Adams, via a letter of introduction from Professor
Challis in Cambridge, had applied to Professor George Biddell Airy, the
Astronomer Royal for some kind of assistance, though he failed to
secure an interview with Airy, and nothing further happened - until
the New Planet was discovered in Berlin, nearly a year later.
Popular interpretations of this incident place a great deal of
responsibility upon Airy, for not having taken the initiative to
secure a British discovery. Yet this is unjust, and several key factors
must be born in mind:
John Couch Adams, while a brilliant mathematician, was rather naive
socially, and was said by a senior Cambridge colleague to have
behaved, regarding Neptune, not "like a man who made a great
discovery, but like a bashful boy." In 1846, however, the "bashful
boy" was 27 years old.
- It was not the job of the Astronomer Royal to undertake searches.
- As an extremely over-worked man, Airy cannot be blamed for
being unavailable when Adams chanced to call upon him without first having made an
appointment. He was abroad on the first occasion, and at dinner with
his family on the second.
- After Adams left his figures for Neptune's place, when the Airy family
were at dinner on October 21st, 1845, Airy was prompt in writing to
Adams in Cambridge, requesting crucial pieces of mathematical information
about the basis of his computations. Adams never replied to Airy's
letter, nor supplied the requested information.
- Why was Adams not admitted when Airy was at dinner? We should bear
in mind that at the time Mrs. Richarda Airy was within a week of giving birth to
their ninth child. Her previous pregnancies had been
difficult, and as Airy was deeply attached to his wife, he saw
no reason to have their dinner interrupted by a stranger who wished to see
him on a business matter. There is no evidence to suggest that Adams was willing
to wait until the meal was over in spite of the fact that the Airy family dined not
in the evening, but in the late afternoon.
- Airy's voluminous surviving correspondence makes it clear that everyone - from
Cabinet Ministers and Admirals, down to servant-girls wanting to have their fortunes
told - wrote to, and occasionally called-in upon the Astronomer Royal. A man who was
so much in the public eye had to defend his privacy.
- While all of this was going on, the Royal Observatory was being
rocked by the disclosure of an awful incident. A senior
Greenwich Observatory Assistant, William Richardson, had just been
exposed for having committed an appalling murder. From late October
1846, onwards, Airy and his Chief Assistant, the Revd Robert Main, made
appearances before the courts at the beginning of Richardson's trial. Airy was
acutely embarrassed by the regular appearance of his name, as Richardson's
employer, in the newspaper columns reporting the details of a crime which
hinged upon sex, incest, and the burial of a body in a shallow grave.
- And if this was not enough, the year 1845-1856 was probably the
busiest in Airy's professional life. For in addition to
astronomy, he was immersed in the business of the Railway Gauge
Commission. As the Scientific Commissioner, he was travelling around
Britain testing trains and interviewing engineers. It was this
Commission, and Airy's scientific advice, which settled British (and,
later American) railway gauges at the "Standard Gauge" of 4 feet 8 1/2
Urbain Le Verrier, the French co-discovery of Neptune was an older,
and much more business-like individual, and had the determination to
see his computations put to effect. Yet even he was not able to find a
French Observatory that was willing to undertake the search, and was
forced to write to colleagues in Berlin. We often forget that the French
scientific establishment let Le Verrier down no less than the British was
accused of having let down Adams. Once the Berlin sighting had been
made, however, the French were quick to turn it into a French National
But to blame Airy for not doing what was not his job anyway - to
search for private individual's privately investigated planet - is
very unjust, especially when one considers the pressures under which
Airy was operating. And if poor Adams had bothered to make
appointments before turning up for interviews, and had also bothered
to answer the letter from the Astronomer Royal, then the discovery of
Neptune might have gone differently.
Yet the real justice of the incident was done when Adams and Le Verrier,
who were two very different types of men, met in 1847. They had the greatest
admiration for each other's work, and became good friends.
Copyright © 20th April 1996 Allan Chapman
- Allan Chapman:
- "Private research and public duty: G.B.Airy and the discovery of Neptune"
Journal for the History of Astronomy, xix (1988) 121-139
[to be re-printed, July 1996, in A. Chapman's volume of Essays, 'Astronomical
Instruments and their Users, Tycho Brahe to William Lassell'.
Variorum Collected Studies, Aldershot, England.]
- Patrick Moore:
The Planet Neptune, An Historical Survey before Voyager,
Praxis-Wiley, 2nd Edition, (Chichester & New York 1996)
- Allan Chapman:
- "The Discovery of Neptune: Was anyone Really to Blame?"
Astronomy Now, Forthcoming, September, 1996
- The Discovery of Neptune.
|| Maintained by Michael Oates
October 4, 2005