JEAN JACQUES D'ORTOUS DE, descended from a noble family at Béziers, was born in that city in 1678, and died at Paris on the 20th of February 1771, at the age of ninety-three. He was one of the most illustrious members of the Academy of Sciences and of the French Academy. Being early connected with the former, he, in the year 1741, succeeded Fontenelle in the office of secre- This station he filled with distinguished success till the year 1744, and, like his predecessor, possessed the faculty of placing the most abstract subjects in the clearest light; a talent which is very rare, but which appears conspicuous in all his works. These are, 1. Dissertation sur les Variations du Baromètre, 1715, in 12mo; 2. Dissertation sur la Cause de la Lumière des Phosphores et des Noctiluques, 1717, in 12mo; 3. Dissertation sur la Glace, 1719, in 12mo; 4. Lettre à M. l'Abbé Bignon sur la Nature des Vaisseaux, 1728, in 4to; 5. Traité Physique et Historique de l'Aurore Boréale, 1733, in 4to; 6. Dissertation sur les Forces Motrices des Corps, 1741, in 12mo; 7. Lettre à Madame du Châtelet sur la question des Forces Vives, 1741, in 12mo; 8. Éloges des Académiciens de l'Académie des Sciences morts en 1741, 1743, et 1747, in 12mo; 9. Lettre au Père Parennin, contenant diverses Questions sur la Chine, in 12mo.

Mairan was much admired in society as a lively and agreeable as well as an intelligent and instructive companion.