Abstract
The motion of Uranus had already nagged at astronomers for decades, and by the mid-1840s had become, if not a crisis of gravitational theory, at least “a worrisome anomaly at the very heart of astronomy”1 The nature of the problem had begun to emerge as early as May 1782, when Lalande noted that the planet newly discovered by Herschel did not appear to be strictly adhering to its prescribed path. At the time, this concern caused no great measure of alarm. Father Placidus Fixlmillner, using the 1690 observation of Flamsteed and that of 1756 by Mayer to backtrack the planet over a larger arc of its path, calculated an orbit and tables of its motion in 1784. Four years later, his tables no longer seemed to suffice. Fixlmillner then attempted to recalculate the planet’s orbit, and in doing so realized he could devise orbits that would satisfy either the old observations or the recent ones made since 1781, but not both. Under the circumstances, he decided to rely only on the recent data.
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Notes and References
Smith, “Cambridge Network,” 398.
This tantalizing remark appears in George Chambers, A Handbook of Descriptive and Practical Astronomy (Oxford, 4th ed., 1889), vol. 1, p. 253 footnote. This statement apparently depends upon a note found among Lalande’s papers presented to the Académie des Sciences in 1852.
Rawlins, “The Unslandering of Sloppy Pierre.”
Alexis Bouvard, Tables astronomiques publiées par le Bureau des Longitudes de France contenant les Tables de Jupiter, de Saturne et d’Uranus construites d’après la théorie de la Mécanique céleste (Paris, 1821), p. xiv.
Grosser, p. 42. The literature on the discovery of Neptune is large. Grosser’s account is still essential and has been largely followed by later writers, not always with due acknowledgement. Other works that deal extensively with the discovery of Neptune include Robert Grant, History of Physical Astronomy (London: Henry G. Bohn, 1852);
H. Spencer Jones, John Couch Adams and the Discovery of Neptune (Cambridge: Cambridge University Press, 1947);
W. M. Smart, “John Couch Adams and the Discovery of Neptune,” Nature 158, 648ff (1946); also the Reply by Spencer Jones, 158, p. 830;
W. M. Smart, “John Couch Adams and the Discovery of Neptune,” Occasional Notes, Royal Astronomical Society no. 2; 33ff (1947);
H. Spencer Jones, “G. B. Airy and the Discovery of Neptune,” Popular Astronomy 55, 312–316 (1947) (which includes a reply by W. M. Smart);
W. G. Hoyt, Planets X and Pluto (Tucson: University of Arizona Press, 1980);
Allan Chapman, “Private Research and Public Duty: George Biddell Airy and the Search for Neptune,” Journal for the History of Astronomy xix, 121–139 (1988);
Mark Littman, Planets Beyond: Discovering the Outer Solar System (New York: Wiley, 1988);
Patrick Moore, The Planet Neptune (New York: Wiley, 1988);
Robert W Smith, “The Cambridge Network in Action: The Discovery of Neptune,” Isis 80, 395–422 (1989);
J. G. Hubbell and Robert W. Smith, “Neptune in America: Negotiating a Discovery,” Journal for the History of Astronomy xxiii, 261–291 (1992).
Smith, “Cambridge Network,” 399: “The possible amendment he examined involved specific attraction, that is, the notion that there might be something specific to or dependent on the nature or chemical constitution of a body that affects its gravitational attraction.”
Bessel, Populäre Vorlesungen, 448; quoted in Grosser, 44.
George Biddell Airy, “Report on the Progress of Astronomy during the Present Century,” Report on the First and. Second Meetings of the British Association for the Advancement of Science (London, 1833), 189.
Such a medium was being invoked about this time by Johann Franz Encke to account for the fact that the comet now named for him (P/Encke, with the shortest period of any comet known, 3.3 years) showed a slight deceleration with each revolution, even after perturbations of the planets had been allowed for. Between 1789 and 1838, the period of Encke’s comet decreased by 1.9 days, which came out to 0.1 day per revolution. The fact that other comets, such as P/Halley, were delayed in their returns was inconsistent with the resisting medium idea.
Smith, “Cambridge Network,” 398.
G. B. Airy, “Account of Some Circumstances Historically Connected with the Discovery of the Planet Exterior to Uranus,” Monthly Notices of the Royal Astronomical Society 7, 123 (1846).
Ibid., 124.
Grosser, 50–51.
W. H. Smyth, “Extract of a letter from Capt. Smyth to the President, Containing the Translation of a Notice from M. Cacciatore,” Monthly Notices of the Royal Astronomical Society 3, 139 (1835).
See also N. Cacciatore, “Sur une nouvelle petite planète dont l’existence a été soupçonnée par M. Cacciatore, directeur de l’Observatoire de Palenne,” Comptes Rendu 2, 154–155 (1836).
See also R. Baum, The Planets: Some Myths and Realities (Newton Abbot: David & Charles, 1973), 163–168.
For Wartmann’s report, see “Lettre de M. Wartmann, de Geneve, à M. Arago, sur un astre ayant l’aspect d’une étoile et qui cependant était doue d’un mouvement propre,” Comptes Rendu 2, 307–311 (1836). Hind’s critique was published as “Wartmann’s Supposed Planet,” Monthly Notices of the Royal Astronomical Society 7, 274 (1847). See also Baum, The Planets, Chap. 8. Theodore Oppolzer finally explained the Wartmann affair in 1880, pointing out that on average the positions given by Wartmann were 6 minutes of time greater in right ascension and about 26 arc seconds farther north than the corresponding places of Uranus. “Whether Wartmann erred in plotting a map or in reading positions from a map, or whether precession was incorrectly applied is difficult to decide. Nevertheless, it is remarkable that subtraction of the approximate precession in a century removes the discrepancy.” See Astronomische Nachrichten 97, 253 (1880). Meanwhile Cacciatore’s object remains unexplained.
Airy, “Account,” 125.
Ibid.
B. A. Gould, Jr., Report of the History of the Discovery of Neptune (Washington, DC: Smithsonian Institution, 1850), p. 1.
F. W. Bessel, “Über die Verbindung der astronomischen Beobachtungen mit der Astronomie,” in Populäre Vorlesungen uber wissenschaftliche Gegenstäde (Hamburg, 1848), pp. 408–457.
Smith, “Cambridge Network,” 399.
Bouvard’s Tables were never published. The details cited here are given in the account of his colleague Emmanuel Liais, L’espace celeste et la natur tropicale (Paris: Gamier Frères, 1866). The authors are indebted to Patrick Moore for making available a copy of his translation of part of this work, “History of the Discovery of the Planet Neptune.”
Comptes Rendu 21, 1050–1055 (1845).
Le Verrier pointed out that Bouvard’s methods for computing the eccentricity of the orbit of Uranus were inconsistent, and yielded three widely different answers, that his first two tables disagreed in the rate of the secular motion of the mean longitude, and that the work contained an unforgivable number of typographical errors.
Le Verrier, abstract of “Recherches sur les mouvements d’Uranus,” Comptes Rendu 22, 907–908 (1846).
He had technical reasons for approaching the problem in this manner. As explained by Lyttleton, even with the distance a/a′ settled, “rightly or wrongly, there still remain eight unknowns, and quite apart from the large task of solving equations of conditions, not all these remaining eight quantities occur linearly. The principal difficulty arises from the unknown ∈′ [the heliocentric longitudel.” To meet this difficulty, “Le Verrier... took 40 values of ∈′ at 9° intervals, so that the whole possible range of from 0° to 360° was covered. For each assumed value of ∈′, the expression for P(t) immediately becomes linear... and it is then possible to solve the equations of condition by least-squares.... This was Le Verrier’s method, but clearly much arithmetical labour is involved in such an approach to the problem.” R. A. Lyttleton, “The rediscovery of Neptune,” Vistas in Astronomy 3, 27–28 (1960).
Gould, 32–33.
Hoyt, 49.
For biographical details concerning Adams, we have followed J. W L. Glaisher, “Biographical Notice,” in J. C. Adams, The Scientific Papers of John Couch Adams, ed. W. G. Adams (Cambridge: Cambridge University Press, 1896), vol. 1, pp. xv- xlviii; Morton Grosser, The Discovery of Neptune (Cambridge, Harvard University Press, 19xx), xx;
and H. M. Harrison, Voyager in Time and Space: The Life of John Couch Adams, Cambridge Astronomer (Lewes, Sussex: The Book Guild, 1994), xx.
Quoted in Grosser, 72.
Written by a fellow undergraduate at St. John’s, William Wordsworth, in his Prelude, III, 60–64. Wordsworth matriculated in 1791.
Harrison, 73.
J. C. Adams, “An Explanation of the Observed Irregularities in the Motion of Uranus, on the Hypothesis of Disturbances Caused by a More Distant Planet; with a Determination of the Mass, Orbit, and Position of the Disturbing Body,” Memoirs of the Royal Astronomical Society 16 (1847); in J. C. Adams, Scientific Papers, vol. 1, p. 8.
Harrison, 19–20.
J. C. Adams, “Letter on de Vico’s Comet,” Times (London), October 15, 1844. This comet, with a period of somewhat more than 5 years, was discovered by de Vico at Rome on August 23, 1844. Subsequently it was lost, but recovered by Edward Swift in 1894. Hence, it is known as Comet de Vico-Swift. It is not to be confused with another comet discovered by de Vico on February 20, 1846, with period 75 years. Although missed at its expected return in 1922, it was recovered in 1995.
J. C. Adams to George Adams, July 10, 1845; quoted in Grosser, 86.
James Challis, “Account of Observations at the Cambridge Observatory for Detecting the Planet Exterior to Uranus,” Monthly Notices of the Royal Astronomical Society 7, 121–149:148 (1846).
Airy, “Account,” 129.
As noted, for instance, in the account by his brother Thomas, “he took with him [his calculations] on his way to Cambridge to the Astronomer Royal at Greenwich.... The result is well known. They were neglected. John was terribly disappointed and annoyed, for which he had great reason.” Harrison, Voyager, 20.
E. W. Maunder, in The Royal Observatory Greenwich (London, 1900), 116.
Ibid., 118.
Allan Chapman, “Private Research and Public Duty: George Biddell Airy and the Search for Neptune,” Journal for the History of Astronomy xix, 134 (1988).
Ibid., 126.
G. B. Airy to J. C. Adams, November 5, 1845; see Airy, “Account,” 130.
Chapman, “Airy and Neptune,” 127–128.
Ibid., 128. Even then he did not say he would have actually looked for the planet.
The query was not, in fact, as trivial as Adams had regarded it, as noted, for instance, in J. E. Littlewood, A Mathematician’s Miscellany (London, 1953), 131. Adams himself eventually was forced to admit he had perhaps “hastily inferred” that the hypothesis of an exterior planet would automatically satisfy the errors in the radius vector.
Comptes Rendu 22, 907–918 (1846).
Airy, “Account,” p. 132.
Quoted in Smith, “Cambridge Network,” 404.
Airy, “Account,” 133.
Le Verrier to Airy, June 28, 1846; in Airy, “Account,” 134.
Airy, “Account,” 135.
After the discovery of Neptune, he explained, rather awkwardly, to Le Verrier: “I do not know whether you are aware that collateral researches had been going on in England and that they led to precisely the same results as yours.” When asked to defend his actions (or inactions) by his friend Adam Sedgwick at Cambridge, he wrote, When about June last Le Verrier published one of the results Adams had attained before (September 1845), why in the name of wonder was not all Europe made to ring with the fact that a B.A. at Cambridge had done this 10 [sic] months previously? “In the name of wonder what had I to do with this publication. No understood rule of Society would have justified me in doing so. The first person to publish was Adams. The second was Challis. The third was I. But there was a very serious difficulty in the way of my doing so, because Adams had declined to answer my letter. Moreover, in consequence of my question not having been resolved, I had not till I received Le Verrier’s explanatory letter the security for the truth of the theory which I desired,...” Quoted in Harrison, Voyager, 69.
Ibid., 136.
Airy, “Account,” 136.
Ibid., 137.
Airy, “Account,” 148.
Le Verrier, “Sur la planète qui produit les anomalies observées dans le mouvement d’Uranus-détermination de sa masse, de son orbite, et le sa position actuelle,” Comptes Rendu 23, 428–438:433 (Aug. 31, 1846).
J. F. W. Herschel, “Le Verriers Planet,” letter, Athenaeum 1019 (Oct. 3, 1846).
Smith, “Cambridge Network,” 411.
Ibid., 409, Rev. Richard Sheepshanks, Nov. 12, 1846.
Ibid., 408, J. R. Hind to James Challis, September 16, 1846.
William Rowan Hamilton recounted Herschel’s comments to Dawes to a correspondent, October, 1846; see Robert Perceval Graves, Life of William Rowan Hamilton, (Dublin/London, 1885), vol. II, p. 529.
E. S. Holden to Jane Lassell, May 9, 1890; Mary Lea Shane Archives of the Lick Observatory. The first published mention of Lassell’s missed opportunity was by E. S. Holden, “Historical Note Relating to the Search for the Planet Neptune in England, 1845–6,” Astronomy and Astro-Physics 11, 287 (1892). Holden however assumed the date of Dawes’ letter as September 1845.
Robert W. Smith considered Lassell’s participation in “William Lassell and the Discovery of Neptune,” Journal for the History of Astronomy xiv, 3 (1983),
but misses an interesting note by A. Marth, “Report of the Meeting of the British Astronomical Association,” Journal of the British Astronomical Association 2, 433–434 (1892). Marth’s source was also Mrs. Lassell. He understood the date of Dawes’s letter was September 1846—only a couple of weeks before the discovery of Neptune—which nicely squares the episode with other developments. The whole Lassell episode is reconsidered by Richard Baum, “William Lassell and ‘the Accident of a Maid-servant’s Carelessness’ or Why Neptune was not Searched for at Starfield,” Journal of the British Astronomical Association 106, 217–219 (1996).
H. H. Turner, Obituary notice of Johann Gottfried Galle, Monthly Notices of the Royal Astronomical Society 71, 275–281:278 (1911).
J. L. E. Dreyer, “Historical Note Concerning the Discovery of Neptune,” Copernicus 2, 63–64 (1882).
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© 1997 Richard Baum and William Sheehan
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Baum, R., Sheehan, W. (1997). Le Verrier’s Planet. In: In Search of Planet Vulcan. Springer, Boston, MA. https://doi.org/10.1007/978-1-4899-6100-6_8
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