ESSAI SUR LES PHÉNOMÈNES RELATIFS AUX DISPARITIONS PÉRIODIQUES DE L'ANNEAU DE SATURNE.

In-16 gr. (mm. 197x119), p. pelle coeva (restaurata), dorso a cordoni con decorazioni e titolo oro su tassello, tagli rossi, pp. (4),XXXII,444, con 1 tav. fuori testo più volte ripieg. che contiene 23 figg. "Rara prima edizione". Cfr. Poggendorff,I,574.Dionis du Séjour, Achille-Pierre (Parigi 1734 - Vernou, Seine-et-Marne, 1794), astronomo e uomo politico; deputato di Parigi agli Stati Generali, poi all'Assemblea nazionale (1789)..; . applied the latest analytic mathematical methods to the study of problems in astronomy. Over a period of almost 20 years from 1764 he wrote a series of memoirs on eclipses, occultations (when one astronomical body comes in front of another), calculating orbits, and other such topics, and these were brought together in a two volume work Traité analytique des mouvements apparents des corps célestes which he published, volume one in 1786 and volume two in 1789.He published two other volumes on mathematical astronomy. The first was Essai sur les comètes en général; et particulièrement sur celles qui peuvent approacher de l'orbite de la terre(1775) which, as the title suggests considers comets and, in particular, shows that the probability of a collision between a comet and the earth is very low. It is interesting, particularly given the interest in this topic today, to see the subject being explored 225 years ago. The second volume is Essai sur les phémomènes relatifs aux disparitions périodique de l'anneau de Saturne: was published in 1776 and, again as suggested by the descriptive title, it explains the variation in the appearance of the rings of Saturn.Solo alc. cc. uniformemente arrossate, altrimenti esemplare ben conservato..