Essai sur les phénomènes relatifs aux disparitions périodiques de l'anneau de Saturne

Octavo, (2) leaves, XXXII and 444 pp., 1 plate.
Red morocco, triple gilt fillet framing the boards, gilt-stamped coat of arms in the center, spine with raised bands decorated with gilt fleurons and fillets, gilt fillet on the edges, gilt inner roll-tooled border, gilt edges. Armorial binding of the period.

202 x 128 mm.

Dionis du Séjour, Achille Pierre. Essay on the Phenomena Related to the Periodic Disappearances of Saturn’s Ring. By M. Dionis du Séjour, of the Royal Academy of Sciences, the Royal Society of London, & Counselor at the Parliament.
Paris, Valade (from the printing house of Gueffier), 1776.

Rare and important first edition of this astronomy treatise complete with the folding plate with 23 figures.

"From 1764 to 1783 Dionis wrote a series of important memoirs on the application of the most recent analytic methods to the study of the principal astronomical phenomena (eclipses, occultations, reductions of observations, determination of planetary orbits, etc.). All these works are dominated by an obvious concern for rigor and by a great familiarity with analytical methods. Their reexamination in the light of present possibilities of calculation would certainly be fruitful." (D.S.B., IV, p. 107).

“It contains all the formulas and all the necessary details for this type of phenomenon" (Lalande, 599).

Voltaire congratulates the author for this work in a letter dated April 6, 1776: "I admit to you that I cannot conceive how a genius occupied with the laws of the entire universe can come down to judge legal cases in a little corner of this world called Gaul" (Œuvres de Voltaire, P., 1834, vol. LXX, p. 6).

Dionis (1734-1794), astronomer and mathematician, was a counselor at parliament, member of the Academy of Sciences, and of the Academies of London, Stockholm, Göttingen.
In 1765, he began a work to which he devoted thirty years with as much diligence as success: the use of algebraic analysis applied to all branches of astronomy, and first to the calculation of eclipses; he exhausted this problem in all its generality. De Séjour was the first who ever devoted himself entirely to this work; he made an important application of it to the determination of the longitudes of a large number of cities, through the eclipses of 1764 and 1769, in the Memoirs of the Academy for 1771.

This work is important for astronomy.

Precious and superb copy printed on large Dutch paper bound in red morocco with the arms of Lamoignon de Malesherbes (1721-1794).

Chrétien-Guillaume de Lamoignon de Malesherbes became deputy to the attorney general of the Parliament of Paris in 1741, counselor at Parliament on July 3, 1744, director of the book trade and first president of the Court of Aids on February 26, 1749, and appointed chancellor; on April 6, 1771, he was exiled and the Court of Aids was disbanded. Recalled by Louis XVI to his duties in November 1774, Malesherbes was appointed minister and secretary of state of the king's household on July 21, 1775. He returned to the council as minister of state on June 7, 1787, but retired as early as 1788. He then lived in retirement and did not leave it in 1792 except to come and defend Louis XVI with Tronchet and de Sèze. Arrested in December 1793, he was guillotined in Paris on April 22, 1794. He had been made an honorary member of the Academy of Sciences on March 7, 1750, the Academy of Inscriptions on June 19, 1759, and had been part of the Académie française since February 16, 1775. A great magistrate, benevolent and simple, Malesherbes was the friend of writers whom he had efficiently protected when he was director of the book trade.