ANNOUNCING THE DISCOVERY

Astronomer John Hind’s letter appeared in The Times of October 1st, announcing the new planet’s discovery. Airy being out of the country, it fell to James Glaisher a senior RGO worker to write an announcement, and he wrote to The Illustrated London News on October 1st. His letter simply said that Leverrier’s prediction had been confirmed by Dr Galle, in Berlin. Two days later, he wrote another letter. He may have been in touch with Challis, because this letter described the latter’s prolonged sky-search and even the ‘seems to have a disc’ remark which Challis averred he had inscribed adjacent to Neptune. This second letter explained that ‘about four months ago’ both Adams and Leverrier had: ‘concluded, independently, from theoretical calculations’ the position of a perturbing planet. These two mathematicians, Glaisher added, ‘agreed in fixing 325 deg. of heliocentric longitude as the most probable position of the perturbing planet ..., ’ which position was ‘very nearly’ true.

The all-important illusion, that agreement of the two astronomers, and perhaps also of the newly-found planet, was within a degree, is here affirmed, and from an impeccable source, viz.the RGO. The only thing in fact within a degree, was the concordance between Leverrier’s prediction and that of the new planet’s celestial longitude,as agreed to 52’: Neptune was found at 327 degrees; Leverrier’s prediction was at 326 degrees and Adams’ 'final' prediction was 329 and a half degrees, in helio longitude.

This second letter of Glaisher’s was identical with the first public announcement by the Reverend James Challis, writing to The Cambridge Chronicle on October 1st. He announced that Adams and Leverrier had both arrived at their similar conclusions ‘four months’ earlier in June, having both ‘agreed on fixing on 325 degrees of heliocentric longitude as the most probable position, which has proved to be very little different from the actual’.

He had been searching for the past two months in this space, he explained. This newspaper was published in Cambridge on the 3rd, so either a copy was rushed to Greenwich that day, or Glaisher met Challis to discuss the matter.

In June, Leverrier had published his first prediction, using a circular orbit, citing 325 degrees as his prediction. Then in July Adams constructed a guide for Challis to use for his sky-search, which essentially took that position, at the epoch specified by Leverrier, and converted it into RA and Dec co-ordinates for telescope use (see "Adams’ July Ephemeris"). This was the document which Challis brandished at the November 13th RAS meeting, emphasizing how useful it had been to him. It gave the movement, through the months, of the Bode-law orbit body, in circular orbit, as Leverrier had explained. (Challis managed to convey the impression that this document was based upon the perturbation-computations which Adams had been performing the year before). It is thus fairly clear, that both Challis at Cambridge and Glaisher at Greenwich were going public with a story based upon these events around June-July. Adams’ July ephemeris had advocated 325 of helio longitude for the beginning of September. Clearly, Challis had this in front of him when he wrote.

On October 5th, Challis wrote a letter to Arago, which Arago at once published in Comptes Rendues, praising Leverrier’s achievement, and claiming to have followed his guidance ‘Je me conformai strictement aux suggestions de cet astronome’ (Oct 12th issue, p.715) and making no mention of Adams.

After that, Challis changed his mind. Carelessly, he explained to the Cambridge Chronicle two weeks later (Oct 17th), he had written his last letter ‘without consulting memoranda,’ and then came out with the now-familiar story. If he ever did possess any such ‘memoranda’ he didn’t keep them. If he had been given predicted elements from Adams the previous September, they were not then remembered (see Challis’ Unseen Testimony). The person doing the sky-search here appears rather vague about why he was doing it, or where he was supposed to be looking.

It was not until seven weeks after D-day (Neptune’s discovery) that the world could be told what Adams’ predictions were supposed to have been. No wonder that Francois Arago described Adams’ work as ‘clandestine.’ At a stormy meeting of the Paris Academy of Sciences on October 19th, Arago fulminated at how ‘Mr Challis so exaggerates the merit of Mr Adams’s clandestine work, that he assigns to the young Cambridge geometer the right to name the new heavenly body’ (Challis and Adams had come up with the name ‘Oceanus’ and proposed in to The Athenaeum,Oct 17th - Arago had received that paper fairly quickly). He described Adams as a ‘young man who has communicated nothing to the public.’

So, why did Adams not come out with his predicted elements, after John Herschels’ letter to The Athenaeum on October 3rd had proclaimed them, and when others had affirmed they were within a degree of Leverrier’s values? Instead, he did something different: within weeks of the discovery, he correctly ascertained not only the distance of the new sphere, as 30.05 AU but even the correct position of its node and orbital inclination (Challis to The Athenaeum, Oct 17th). With alacrity, he had made use of Challis’ recorded positions of Neptune, from the sky-search. Leverrier had categorically stated, in his August 31st prediction, that the mean distance of the planet could not be less than 35 AU, so this was a significant British coup. It is clear that Adams showed no reticence once he could be confident of his calculations. He was the first to ascertain the true elements of Neptune and quickly released these for publication - weeks before he made known his predicted elements, supposedly from the year before. Adams only came out with these ‘predictions’ within the context of the computations from which he had derived them, to the RAS on November 13th.

LeVerrier pictures by permission of the Observatoire de Paris Archives