1911 Encyclopædia Britannica/Delisle, Joseph Nicolas

by Agnes Mary Clerke

DELISLE, JOSEPH NICOLAS (1688–1768), French astronomer, was born at Paris on the 4th of April 1688. Attracted to astronomy by the solar eclipse of the 12th of May 1706, he obtained permission in 1710 to lodge in the dome of the Luxembourg, procured some instruments, and there observed the total eclipse of the 22nd of May 1724. He proposed in 1715 the “diffraction-theory” of the sun’s corona, visited England and was received into the Royal Society in 1724, and left Paris for St Petersburg on a summons from the empress Catherine, towards the end of 1725. Having founded an observatory there, he returned to Paris in 1747, was appointed geographical astronomer to the naval department with a salary of 3000 livres, and installed an observatory in the Hôtel Cluny. Charles Messier and J. J. Lalande were among his pupils. He died of apoplexy at Paris on the 12th of September 1768. Delisle is chiefly remembered as the author of a method for observing the transits of Venus and Mercury by instants of contacts. First proposed by him in a letter to J. Cassini in 1743, it was afterwards perfected, and has been extensively employed. As a preliminary to the transit of Mercury in 1743, which he personally observed, he issued a map of the world showing the varied circumstances of its occurrence. Besides many papers communicated to the academy of sciences, of which he became a member in 1714, he published Mémoires pour servir à l’histoire et au progrès de l’astronomie (St Petersburg, 1738), in which he gave the first method for determining the heliocentric co-ordinates of sun-spots; Mémoire sur les nouvelles découvertes au nord de la mer du sud (Paris, 1752), &c.

See Mémoires de l’acad. des sciences (Paris, 1768), Histoire, p. 167 (G. de Fouchy); J. B. J. Delambre, Hist. de l’astronomie au XVIII^e siècle, pp. 319, 533; Max. Marie, Hist. des sciences, vii. 254; Lalande, Bibl. astr. p. 385; and Le Nécrologe des hommes célèbres de France (1770). The records of Delisle’s observations at St Petersburg are preserved in manuscript at the Pulkowa observatory. A report upon them was presented to the St Petersburg academy of sciences by O. Struve in 1848, and those relating to occultations of the Pleiades were discussed by Carl Linsser in 1864. See also S. Newcomb, Washington Observations for 1875, app. ii. pp. 176-189.  (A. M. C.)