MAUPERTUIS, Peter Louis Moreau de (1698-1759), a mathematician and astronomer of considerable reputation in his day, was born at St Malo, July 17, 1698. When twenty years of age he entered the army, becoming lieutenant in a regiment of cavalry, and employing his leisure on mathematical studies. After five years he quitted the army and was admitted in 1723 a member of the academy of sciences. In 1728 he visited London, and was elected a fellow of the Royal Society. In 1736 he acted as chief of the expedition sent by Louis XV. into Lapland to measure the length of a degree of the meridian within the polar circle, in order to settle the then much disputed question of the oblate figure of the earth, and, on his return home, he became a member of almost all the scientific societies of Europe. In 1740 Maupertuis went to Berlin on the invitation of the king of Prussia, and took part in the battle of Mollwitz, where he was taken prisoner by the Austrians. On his release he returned to Berlin, and thence to Paris, where he was elected director of the academy of sciences in 1742, and in the following year was admitted into the Academy. Returning to Berlin in 1744, Maupertuis married a lady of rank and great beauty, and in 1746 was chosen president of the royal academy of sciences. Finding his health declining, he repaired in 1757 to the south of France, but went in 1758 to Basel, where he died July 27, 1759. Maupertuis was unquestionably a man of considerable ability as a mathematician, but his restless, gloomy disposition involved him in constant quarrels, of which his controversies with König and Voltaire during the latter part of his life furnish examples....