# The New International Encyclopædia/Euler, Leonhard

**EULER**, oi′lẽr, 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 masting of ships, which received a
prize of the French Academy of Sciences in 1727.
In that year Euler went to Saint Petersburg
upon the invitation of Catharine I., 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 department,
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 1766 he was called back to Saint Petersburg,
where he remained until his death. Euler
lost one eye as the result of a severe illness in
1735, and soon after his return to Russia in
1766 he lost the use of the other. This did not,
however, hinder his mental activity, and he
contributed extensively to the science of
mathematics until the day of his death.

The number no less than the value of Euler's
mathematical writings was very great. He wrote,
aside from his separate treatises, 473 memoirs
published during his life, 200 published soon
after his death, and 61 others of which the
publication was undertaken by P. H. and N. Fuss in
1849. Of his more important treatises, the
following may be mentioned: *Mechanica sive Motus*
*Scientia Analytice Exposita* (1736; 2d ed. 1742);
*Tentamen Nova Theoriæ Musicæ* (1739); *Einleitung*
*in die Arithmetik* (1742); *Methodus Inveniendi*
*Lineas Curvas Maximi Minimive Proprietate*
*Gaudentes* (1744); *Theoria Motuum Planetarum*
*et Cometarum* (1744; German edition 1781);
*Opuscula Varii Argumenti* (3 vols., 1746-51);
*Gedanken von den Elementen der Körper* (1746);
*Lettres à une princesse d'Allemagne sur quelques*
*sujets de physique et de philosophie* (1768-72;
2d ed. by Cournot, 1842; German edition, Stuttgart,
1853; English edition, New York, 1833).
His text-books were relatively less important;
they include the following: *Introductio in*
*Analysin* *Infinitorum* (1748; French edition 1796-97;
German edition, 1785-90); *Institutiones Calculi*
*Differentialis* (1755; 2d ed. 1804; German
edition 1790-98); *Institutiones Calculi Integralis*
(3 vols., 1768-70; 3d ed., 4 vols., 1824-45;
German edition, 4 vols., 1828-40); *Anleitung zur*
*Algebra* (1771; 3d ed. 1821; French edition
1770; 2d ed. 1795, and Paris, 1807; American
edition 1818, 2d ed. 1821); *Dioptrica* (3 vols.,
1769-71); *Theoria Motuum Lunæ Nova Methodo*
*Pertractata* (1772); *Opuscula Analytica* (1783-85).
For biography of Euler, consult:
Condorcet, *Eloge*, in Euler's *Institutiones Calculi*
*Differentialis*, and in his *Lettres à une princesse*
*d'Allemagne*; also Fuss, *Correspondance*
*mathématique et physique* (Saint Petersburg, 1843).