Paris, J. [L.] Boilly, 1820. Engraved, tinted broadsheet (36.3 x 27.3 cm).

A rarely-seen portrait of the French mathematician, trogonometrist, and astronomer Jean Dominique Cassini (1748-1845), great-grandson of Giovanni Domenico Cassini. Cassini was born at the Paris Observatory. He succeeded his father as director of the observatory in 1784; but his plans for its restoration and re-equipment were wrecked in 1793 by the animosity of the National Assembly. His position having become intolerable, he resigned on 6 September and was thrown into prison in 1794, but released after seven months. He then withdrew to Thury (Yonne), where he died. In 1770, he published an account of a voyage to America in 1768, undertaken as the commissary of the French Academy of Sciences with a view to testing Pierre Le Roy’s watches at sea. In 1783, his father César-François Cassini de Thury had sent a letter to the Royal Society in London, in which he proposed a trigonometric survey connecting the observatories of Paris and Greenwich for the purpose of better determining the latitude and longitude of the latter. His proposal was accepted, resulting in the Anglo-French Survey (1784-1790). The results of the survey were published in 1791. Dominique, comte de Cassini visited England with Pierre Méchain and Adrien-Marie Legendre, and the three met William Herschel at Slough. He completed his father's map of France, which was published by the Academy of Sciences in 1793. It served as the basis for the Atlas National (1791), showing France in departments." (Wikipedia). The artist, Julien-Léopold Boilly (1796-1874) was noted for his album of lithographs, Iconographie de l'Institut royal de France ou collection des portraits des Membres composant les quatre académies depuis 1814 jusqu'en 1825 (1820-1825). His portraits are much less stiff and formal than many by his contemporaries. Signed by the artist in the lower margin of the portrait and dated 1820. The caption states the date of Cassini's birth and the years (1770, resp. 1799) in which he was elected as a member of the Académie and of the Institut. Uncut. Scattered, very mild foxing, mostly in the outer margins; a very short (7 mm) tear in the lower margin; otherwise very good.