HANSEN, (PETER ANDREAS).

Mémoire sur le Calcul des perturbations qu'éprouvent les Comètes.

(Paris, Mallet-Bachelier), 1856.

4to. No wrappers. In: "Supplément aux Comptes rendus hebdomadaires des séances de l’Académie des sciences", Tome Premier. Pp. 121-378. Clean and fine.

First printing of Hansen's great memoir, exposing his theory of the pertubed motions of comets.

"Modest as was the public position that Hansen held, he may now fairly be considered the greatest master of celestial mechanics since Laplace. In what order Leverier, Delaunay, Adams, and Hill should follow him, it is not necessary to decide. To many readers it will seem singular to place any name ahead of that of the master who pointed out the position of Neptune before a human eye had ever recognized it. But this achievement, great as it was, was more remarkable for its boldness and brilliancy than for its inherent difficulty. If the work had to be done over again today, there are a number of young men who would be as successful as Leverrier; but there are none who would attempt to reinvent the methods of Hansen, or even to improve radically upon them."( Simon Newcomb "Reminiscences of an Astronomer",New York, 1903, p.315).

Order-nr.: 49469