EULER, oi'Fir, LEONHARD ( 1707-83). A Swiss mathematician, one of the most remarkable of his century. He was born at Basel. Euler was sent to the University of Basel so early and was so proficient in his work that he received the master's degree at the age of sixteen. He studied mathematics under Johann Bernoulli at Basel, and also studied theology, the Oriental languages, and medicine. In the course of his physiological researches he wrote a treatise on the nature and propagation of sound, and he also wrote an essay on the roasting of ships, which received a prize of the French',Iicademy of Sciences in 1727. In that year Euler went to Saint Petersburg upon the invitation of Catharine 1., and became an associate of the Academy of Sciences. In 1730 he was made professor of physics, and in 1733 professor of higher mathematics. In 1740 he became inspector of the geographical depart ment, and in the following year was called to Berlin by Frederick II. to take the chair of mathematics in the Academy of Sciences, from which he was not long afterwards advanced to the position of director of the mathematical class. In 1760 he was called back to Saint Peters burg, where he remained until his death. Euler lest one eye as the result of a severe illness in 1735. and soon after his return to Russia in 1760 he lost the use of the other. This did not, however, hinder his mental activity, and he contributed extensively to the science of mathe matics until the day of his death.
The number no less than the value of Enler's mathematical writings was very great. wrote, aside from his separate treatises, 473 memoirs published during his life, 200 published soon after his death, and 01 others of which the pub lication was undertaken by P. 11. and N. Fuss in
1849. nf his more important treatises, the fol lowing may be mentioned: Mechanira sire Mains Scientia A nalytice •xposita (1736; 2d ed. 1742) : Ten/a/urn Norm Theorim Musicw (1739) ; Pin/ef t/111g in dir Arithmetik (17 i2) ; Methodus In•eni endi Linens Curras Minhnire Proprietor Gamlen es ( 1744 ) ; Theoria hunt( I'la ne t a rum et Cometarnm (1744; German edition 1781) ; Opuseula Varii Argnmenti (3 vols., 1746-51) ; Ge danken ton den Elcmenten der !carper (1746); Leitres one princess(' d'Allemagne sur quelques su jets dr phusique et de philosophic (17(1S 72; 2(1 ed. by Commit, 1842; German edition, Stutt gart, 1853; English editIon, New York, 1833). this text-books were relatively less important; they include the following: Introductio in .1naly sin Infinitorum French edition 1796-97; German edition, 1785-90) ; Institutiones Calculi Differentialis (1755; 2d ed. 1804; German edi tion 1790-9S) ; Institutiones Calculi Integralis (3 vols., 1768-70; 3d ed., 4 vols., 1824-45; Ger man edition, 4 vols., 1828-40) ; Anleitung zur Algebra (177]; 3d ed. 1821 ; French edition 1770; 2d ed. 1795, and Paris, 1807; American edition 1818, 2d ed. 1821) ; Dioptrica (3 vols., 1769-71) ; Theoria Notuum Luna, Nora Method() Pertraelata (1772); Opuscula Analytica (1783 85). For biography of Euler, consult: Con dorcet, Eloge, in Euler's Institutiones Calculi Differentiulis, and in his Lettres a une princesse d'Allemugne; also Fuss, Correspondence mathe matique et physique (Saint Petersburg, 1343).