Jean-le-Rond D'Alembert was born at Paris on November 16, 1717, and died there on October 29, 1783. He was the illegitimate child of the chevalier Destouches. Being abandoned by his mother on the steps of the little church of St. Jean-le-Rond, which then nestled under the great porch of Notre-Dame, he was taken to the parish commissary, who, following the usual practice in such cases, gave him the Christian name of Jean-le-Rond.

He was boarded out by the parish with the wife of a glazier in a small way of business who lived near the cathedral, and here he found a real home, though a humble one. His father appears to have looked after him, and paid for his going to a school where he obtained a fair mathematical education.

D'Alembert first attended a private school. The chevalier Destouches left d'Alembert an annuity of 1200 livres on his death in 1726. Under the influence of the Destouches family, at the age of twelve d'Alembert entered the Quatre-Nations jansenist college (the institution was also known under the name Mazarin). Here he studied philosophy, law, and art, graduating as bachelier in 1735.

He was also interested in medicine and mathematics. Jean le Rond was first registered under the name Daremberg, but later changed it to d'Alembert.

In July of 1739 he made his first contribution to the field of mathematics, pointing out the errors he had detected in L'analyse demontree (published 1708 by Charles Rene Reynaud) in a communication addressed to the Academie des Sciences. At the time L'analyse demontree was a standard work, which d'Alembert himself had used to study the foundations of mathematics.

In July 1739 d'Alembert read his first paper to the Paris Academy of Science on some errors he had found in Reyneau's standard text Analyse demontree which were not of great significance but marked the start of his mathematical career. In 1740 he submitted a second work on the mechanics of fluids which was praised by Clairaut. In May 1741 d'Alembert was admitted to the Paris Academy of Science, on the strength of these and papers on the integral calculus. It took some determination on his part, submitting three unsuccessful applications in quick succession, before his appointment

Nearly all his mathematical works were produced during the years 1743 to 1754. The first of these was his Traite de dynamique, published in 1743, in which he enunciates the principle known by his name, namely, that the ``internal forces of inertia'' (that is, forces which resist acceleration) must be equal and opposite to the forces which produce the acceleration. This may be inferred from Newton's second reading of his third law of motion, but the full consequences had not been realized previously. The application of this principle enables us to obtain the differential equations of motion of any rigid system.

Euler had learnt of d'Alembert's work in around 1743 through letters from Daniel Bernoulli. However, Daniel Bernoulli became highly critical of d'Alembert after reading his "Traite de l'equilibre et du mouvement des fluids". When d'Alembert won the prize of the Prussian Academy of Sciences with his essay on winds he produced a work which Euler considered superior to that of Daniel Bernoulli. Certainly at this time Euler and d'Alembert were on very good terms with Euler having high respect for d'Alembert's work and the two corresponded on many topics of mutual interest.

He suffered bad health for many years and his death was as the result of a bladder illness. As a known unbeliever, d'Alembert was buried in a common unmarked grave.


back