D'Alembert et l'astronomie

Jacques Lévy : D'Alembert and astronomy. D'Alembert's works on astronomy, written mainly between 1744 and 1756, concern essentially celestial mechanics ; they deal with the figure of the Earth, a body's movement around its centre of gravity, and the problem of three bodies (including the Moon's motion). The main positive result obtained concerns the movement of the Earth's axis (1749) : for the first time the movement of precession was calculated rigorously, and the phenomenon of nutation, which had just been discovered by Bradley, was described with a greatly superior precision to that of experimental findings. The other problems were too complex to be solved by d'Alembert's general form of mathematical analysis ; nevertheless he provided methods and tools that were to be used later, notably by Laplace, part of whose work was founded on them.Levy Jacques. D'Alembert et l'astronomie. In: Dix-huitième Siècle, n°16, 1984. D'Alembert. pp. 47-53