Dominique, comte de Cassini

Jean-Dominique, comte de Cassini (30 June 1748  18 October 1845) was a French astronomer, son of César-François Cassini de Thury.

Dominique, comte de Cassini
Jean-Dominique, comte de Cassini, 1820. Lithograph by Julien-Léopold Boilly.
Born(1748-06-30)30 June 1748
Died18 October 1845(1845-10-18) (aged 97)
Known forTerrestrial surveys
ChildrenHenri Cassini

Cassini was born at the Paris Observatory. In 1784, he succeeded his father as director of the observatory; 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, where he died in 1845.[1]

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.[1] In 1783, he sent a memoir to the Royal Society 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).[2] The results of the survey were published in 1791. He visited England for the purposes of the work 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.[1] He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1788.[3]

Cassini's Mémoires pour servir à l’histoire de l’observatoire de Paris (1810) embodied portions of an extensive work, the prospectus of which he had submitted to the Academy of Sciences in 1774. The volume included his Eloges of several academicians, and the biography of his great-grandfather, Giovanni Cassini.[1]

His youngest son Henri was a botanist of some note.


  1.  One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Cassini s.v. Jacques Dominique Cassini". Encyclopædia Britannica. 5 (11th ed.). Cambridge University Press. p. 459.
  2. Maskelyne, Nevil (1785). "Concerning the Latitude and Longitude of the Royal Observatory at Greenwich; With Remarks on a Memorial of the Late M. Cassini de Thury". Philosophical Transactions of the Royal Society of London. 75: 385–480. doi:10.1098/rstl.1785.0024. See the article on William Roy.CS1 maint: postscript (link)
  3. "Book of Members, 1780–2010: Chapter C" (PDF). American Academy of Arts and Sciences. Retrieved 28 July 2014.

See also : Paris Observatory digital library