I. Guillaume De, a French geographer, born in Paris, Feb. 28, 1675, died Jan. 25, 1726. He was the son of Claude de Lisle, a geographer and historian of some note, and at the age of nine had constructed several charts of ancient history. He wholly reconstructed the system of geography current in Europe in 1700, by the publication of maps of the world, and of Europe, Asia, and Africa, in which he corrected many of the errors that had been copied with little alteration into all the works on geography since the time of Ptolemy. He also constructed a celestial and terrestrial globe. He was admitted to the academy of sciences in 1702, and was afterward appointed tutor in geography to Louis XV., who created for him in 1718 the title of "first geographer to the king," with a pension of 1,200 livres. De Lisle drew up several maps for the use of his royal pupil, and the whole number made by him is said to amount to 134. In 1724 he published a corrected edition of his map of the world. He contributed several memoirs to the Recueil de l'academie des sciences.
II. Joseph Nicolas, a French astronomer, brother of the preceding, born in Paris, April 4, 1688, died there, Sept. 11, 1768. He first brought himself into notice in 1706 by an essay on an eclipse of the sun. In 1714 he was chosen a member of the French academy, and in 1724 visited England, where he was elected a fellow of the royal society. On the invitation of Catharine I. in 1726, he went to St. Petersburg, where he had charge of the observatory till 1747, when ill health obliged him to return to France. While in Russia he had made a collection of objects illustrative of geography and astronomy, which on his return was purchased by Louis XV., and De Lisle charged with the care of it. He also became a professor in the royal college of France.