LE VERRIER, URBAIN JEAN JOSEPH. - PREDICTING THE EXISTENCE OF THE PLANET NEPTUN.

Paris, Bachelier, 1846.

4to. No wrappers. In: "Comptes rendus hebdomadaires des séances de l’Académie des sciences", Vol. 23, No 9 (entire issue offered). With htitle and titlepage to vol. 23. Pp. 425-484. Le Verrier's paper: pp. 428-438.

First printing of this important paper in the history of astronomy in which Le Verrier predicted the existence of a new planet, determining its orbit and the mass as well as its actual position, so that, by informing Dr. Galle the following month, where he should look for it in the sky. The same evning when Galle had received the letter, he found close to the position given by Le Verrier a strange body showing a small planetary disc, which was soon recognized as a new planet, known now as Neptune. Adams in England, independently made the same prediction.

"Until 1846 there was no theory of Uranus that permitted its movements to be represented satisfactorily. In 1821 Bouvard had constructed tables that, abandoning the older positions, adhered very closely to recent observations. Yet twenty years later a discrepancy of two minutes had already been observed, and several astronomers suggested that it might result from the attraction of an unknown planet. In 1845 Arago presented the problem to Le Verrier, who began by establishing a precise theory of Uranus. He then demonstrated that its observed perturbations could not be explained as the effect of the actions of Jupiter and Saturn, whatever modifications might eventually be made in the values assigned to the masses of those planets. He began to search for signs of an unknown disturbing planet. Finally, in a third memoir on the subject, appearing on 31 August 1846, Le Verrier fixed the exact position of the unknown planet and gave its apparent diameter."(DSB)

Order-nr.: 46890