Jean-Dominique, comte de Cassini (30 June 174818 October 1845) was a French

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

, son of César-François Cassini de Thury and great-grandson of

Giovanni Domenico Cassini Giovanni Domenico Cassini, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the ...

. 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 In politics, a national assembly is either a unicameral legislature, the lower house of a bicameral legislature, or both houses of a bicameral legislature together. In the English language it generally means "an assembly composed of the rep ...

. 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. 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 Pierre Le Roy (1717–1785) was a French clockmaker. He was the inventor of the detent escapement, the temperature-compensated balance and the isochronous balance spring. His developments are considered as the foundation of the modern precisi ...

’s watches at sea. In 1783, he sent a memoir to the

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

in which he proposed a

trigonometric Trigonometry () is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. ...

survey connecting the observatories of Paris and

Greenwich Greenwich ( , ,) is a town in south-east London, England, within the ceremonial county of Greater London. It is situated east-southeast of Charing Cross. Greenwich is notable for its maritime history and for giving its name to the 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 Anglo-French Survey (1784–1790) was the geodetic survey to measure the relative position of Greenwich Observatory and the Paris Observatory via triangulation. The English operations, executed by William Roy, consisted of the measureme ...

. The results of the survey were published in 1791. He visited

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

for the purposes of the work with

Pierre Méchain Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets. Life Pierre Méchain was born i ...

and

Adrien-Marie Legendre Adrien-Marie Legendre (; ; 18 September 1752 – 9 January 1833) was a French mathematician who made numerous contributions to mathematics. Well-known and important concepts such as the Legendre polynomials and Legendre transformation are name ...

, and the three met

William Herschel Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline ...

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. He was elected a Foreign Honorary Member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, a ...

in 1788. 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 th
biography of his great-grandfather

Giovanni Cassini Giovanni Domenico Cassini, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the ...

. His wife was Claude Marie Louise de Lamyre-Mory Comtesse de Neuville (1754–1791) and their youngest son Henri was a botanist of some note.

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* {{DEFAULTSORT:Cassini, Dominique 1748 births 1845 deaths Scientists from Paris French cartographers 18th-century French astronomers French people of Italian descent 19th-century French astronomers Fellows of the American Academy of Arts and Sciences Members of the French Academy of Sciences Foreign Members of the Royal Society