Cassini

Cassini. The name of a family of astronomers which furnished for four generations directors to the observatory of Paris.

1. C. Giovanni Domenico (1625-1712), born near Nice, was educated by the Jesuits of Genoa. His studies in astrology led him on to that of astronomy, and in 1650 he was professor of astronomy at the University of Bologna. He made observations upon the comet of 1652, and formed a theory of comets. He showed himself a man of general science, and also displayed great practical abilities, so that it was only upon a promise to return that Pope Clement IX. allowed him to start for France, where he was offered the post of director of the Paris observatory. He became naturalised, and married a French lady, and in 1671 began the series of discoveries that made him the most renowned astronomer of Europe.

2. C. Jacques (1677-1756) succeeded his father as director, and like him was an original observer, but had little knowledge of contemporary thought, though he was acquainted with Newton.

3. Caesar (1714-1784), son of the above-mentioned Jacques, succeeded his father as director, and also published a topographical map of France.

4. Jacques Domenique (1748-1845), son of Caesar C. The fourth and last of the line of directors. He was the most philosophical of the family, and in 1769 undertook a voyage to test Le Roy's chronometers, and also took part in 1779 in the work of connecting the Paris and Greenwich observatories by means of a chain of triangles. A dispute with the National Assembly in 1793 caused him to be imprisoned for seven months, after which he abandoned astronomy and retired into private life.