Le Verrier (Urbain Jean Joseph) Recherches sur les mouvements d'Uranus, first edition, first offprint issue, original blue printed wrappers bound in, front wrapper with Japanese tissue repairs to a few minor defects, partially stuck to following endpaper, rear wrapper stained, 20th century half-calf, light scuffing to front corner and spine, else excellent, 8vo, Paris, Bachelier, 1846.

⁂ Extremely rare edition of Le Verrier's mathematical prediction of the existence of Neptune, undeniably one of the major scientific events of the 19th century (Lequex). This issue precedes both the journal appearance in Connaissance des Temps and the second offprint issue. Neptune, whose existence was visually confirmed in 1846, was the first planet to be discovered by mathematical calculation rather than observational means: the discovery of Neptune not only represents the greatest triumph for Newton's gravitational theory since the return of Halley's Comet in 1758, but it also marks the point at which mathematics and theory, rather than observation, began to take the lead in astronomical research.