EULER, LEosAnn, one of the most distinguished mathematicians of the 1 Sth century, was the son of Paul Euler, and Margaret Brucker, and was born at Basle on the 15th of April 1707.
His father, who had been instructed in mathematics by the celebi ated James Bernoulli, became pastor of the village of Riechen, near Basle, in the year 1708 ; and as soon as his son had arrived at the proper age, he instilled into him a fondness for mathematical learning, although lie had destined him lee the study of theology. Ile was afterwards sent to the university of Basle, where he was found worthy to receive lessons from John Bernoulli, who was at that time regarded as the first mathemati cian in Europe. The assiduity and amiable disposition or Euler, soon gained him the particular esteem of that great master, and the friendship of his two sons Daniel and Nicolas Bernoulli, who had already become the dis ciples and the rivals of their father. John Bernoulli even condescended to give him once every week a par ticular lesson, for the purpose of explaining the dnEcul ties which he encountered in the course of his studies. Euler had not the good lorttme to enjoy long this inesti mable advantage. In 1723, he received the degree of Master of Arts ; and on this occasion, lie obtained great applause by the Latin discourse which he delivered, containing a comparison between the Newtonian and the Cartesian philosophy. At the request of his father, he now began the study of theology ; but his attachment to the mathematics was so strong, that his father at last consented to allow him to follow the bent of his own b .-e nius.
Nicolas and Daniel Bernoulli having accepted in 1725 of the invitation of Catherine I. to become a member of the Academy of Sciences of St Petersburg, promised t their departure to employ their influence, to procure for Euler an appointment in that city. In the following year they wrote to him, that they had a situation in view for him, and strongly' advised him to apply his mathemati cal knowledge to physiology. Euler immediately attend ed the lectures of the most eminent medical professors of Basle, and made rapid progress in the study of medi cine. His attention, however, was still directed to his favourite pursuits, and he found leisure to compose a dissertation on the Nature and Propagation of Sound, and another on the ]I lasting of Shifts, which was written for the prize proposed by-the Academy of Sciences in 1727. As this subject was actually suggested by several mem bers of the Academy, with the view of bringing into no tice the talents of M. Bouguer, who had paid particular attention to this subject, and who was then professor of hydrography in the sea-port town of Croisic, it was not likely that Euler, who was destitute of all practical knowledge of the subject, should have succeeded in the competition. Bougeur, of course, carried off the first prize ; but Euler obtained what is called the accessit, or second prize, an honour of no trivial magnitude, when we consider that he was then only 20 years of age. About this time, Euler was a candidate for the vacant profes sorship of natural philosophy in the university of Basle ; but he had not the good fortune to be elected.
Daniel and Nicolas Bernoulli used all their influence to procure an appointment for their young friend ; and having at last succeeded, they requested him to repair immediately to St Petersburg. Euler lost no time in
obeying this welcome summons; but, after he had begun his journey, he had the mortification to learn that Nico las Bernoulli had fallen a victim to the severity of the climate ; and the very day upon which he entered the Russian territory, was that of the death of the Empress Catherine I.: an event which at first threatened the dis solution of the Academy, of which she had laid the foun dation. Having reached St Petersburg at this unfortu nate period, Euler resolved to enter into the Russian navy, and had actually received the promise of a lieute nancy and rapid promotion from Admiral Sievers; but fortunately for geometry, a change took place in the as pect of public affairs in 1730, and Euler obtained the si tuation of Professor of Natural Philosophy. In 1733 he succeeded Daniel Bernoulli, when that illustrious ma thematician retired into the country ; and in the same year he married Mademoiselle Gsell, a Swiss lady, and the daughter of a painter, whom Peter the Great had carried into Russia upon his return from his first tour. In 1735,6 very intricate problem having been proposed by the Academy of St Petersburg, Euler completed the solution of it in three days; but the exertion of his mind had been so liulent, that it threw him into a fever, which endangered his life, and deprived him of the use of one of his eyes. In 1738, the Academy of Sciences at Paris crowned his memoir, entitled, Sur la Aiiture et les Propri etes du feu, and in 1740, he divided with Daniel Ber noulli, and our countryman Colin Maclaurin, the prize given by the same Academy, for the best dissertation on the flux and reflux of the sea. Daniel Bernoulli had treated the subject with a sagacity and method which characterized all his labours. The dissertation of Ma claurin contained his celebrated theorem on the equili brium of elliptical spheroids ; and that of Euler contain ed an improvement on the integral which seem.
eel to resolve the fundamental equation of almost all the great problems on the motions of the heavenly bodies.
In consequence of an invitation from the king of Pros s;a, through his minister the Count de Mardefeld, Euler quittcd St Petersburg, and went to Berlin in the mouth of June 1741. Upon his arrival, he was honoured with a letter from the King of Prussia, written from his camp of R,:iclicnbach, and he was soon after presented to the queen-mother, a princess who took great pleasure in the conversation of illustrious men. She treated Euler with the utmost familiarity ; but never being able to draw him into any conversation but that of monosyllables, she one day asked him why he did not wish to speak to her ? " Madam," replied Euler," it is because I have just come from a country where every person who speaks is hanged." The memoirs and works with which Euler enriched mathematics and physics are so extremely numerous, that it would occupy many of our pages to give even the briefest account of them. We shall, therefore, con tent ourselves with referring the reader to the articles