J. Brit. Astron. Assoc., 107, 4, 1997, p.222
Plenum Press, 1997. ISBN 0-306-45567-6. Pp xiv + 310, $28.95 (hbk).
reviewed by Patrick Moore
It is now more than a hundred and fifty years since Johann Galle and Heinrich d'Arrest, working at the Berlin Observatory, discovered the planet Neptune. That they were the actual discoverers is not in doubt, but they had been searching on the basis of calculations made by the French mathematician and astronomer U. J. J. Le Verrier; the position which Le Verrier gave had been worked out from the perturbations exerted by Neptune on the inner giant planet, Uranus. It was a triumph of calculation - and let us not forget that the same result, or virtually so, had been reached in England by John Couch Adams. The story of the discovery of Neptune - how Adams finished his work first, sent it to the then Astronomer Royal, and was beaten in the race - has been told many times, and in fact almost half this new book by Baum and Sheehan is devoted to it. It is related in considerable detail, and there are extensive references - though it is a pity that the authors give credence to the long-discredited story that William Lassell, the famous English amateur, was alerted to the possibility of a new planet and was prevented by a sprained ankle from joining in the hunt.
The discovery of Neptune made Le Verrier world famous, but his next investigation, the search for an intra-Mercurial planet, came to a very different conclusion. Mercury was not moving as it might have been expected to do; could there be an inner planet pulling it out of position? Le Verrier believed so, and his faith in the planet was never shaken. The planet was even given a name: Vulcan, after the blacksmith of the gods. Obviously it would be difficult to see, because it was bound to remain very close to the Sun in the sky. The only chance of glimpsing it would be either to catch it in transit across the Sun's face, or identify it at the time of a total solar eclipse. In 1859 Lescarbault, a French country doctor and amateur astronomer, announced that he had seen the planet in transit; Le Verrier made haste to see him - and accepted the story. Confirmation was lacking, but there was a revival of interest in 1878, when two well-known observers - Swift and Watson - surveyed the neighbourhood of the totally eclipsed Sun and reported finding not one Vulcan, but several.
Baum and Sheehan tell the story well, with all its twists and inconsistencies. All in all it is hard to see how a man such as Le Verrier, noted for his 'irritability', could have been convinced by Lescarbault, and later in his life Lescarbault claimed another discovery, that of a bright starlike object which, he said, he had 'never seen until today... I believe I saw it well, and was not the victim of an illusion.' In fact, the good doctor had made a completely independent discovery of Saturn, and this surely shows his lack of elementary knowledge. Other claims of seeing Vulcan were equally dubious; there was for instance the Chevalier D'Angos, who was a complete charlatan and who made a habit of reporting comets which did not exist at all. And in time the motions of Mercury were fully explained by Einstein's theory of relativity.
Vulcan does not exist, and never did; the hunt for it was finally abandoned after the total solar eclipse of 1929. Yet the story is intriguing, and this book fills a notable gap in the literature. Strongly recommended.
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