Who is Jean le Rond d’Alembert?

Who is Jean le Rond d’Alembert?

June 25, 2021 Off By Felso

Jean le Rond d’Alembert (16 November 1717 – 29 October 1783) was a French mathematician, mechanic, physicist and philosopher.

He was also associate editor of the Encyclopédie with Denis Diderot. D’Alembert’s method for wave equations was named after him.

French mathematician, physicist and thinker. He is best known for his theorem known as “D’Alembert’s principle” and for his pioneering in the field of particular (partial) differential equations.

He was baptized as Jean Baptiste le Rond on November 16, 1717, as he was found on the steps of the church of Saint-Jean-le-Rond in Paris. Jean, who grew up under the auspices of a glassmaker named Rousseau and his wife, later turned out to be the illegitimate son of the Marquis of Tencin Claudine Alexandrine Guerin and the artillery officer knight Louis Camus Destouches. Madame de Tencin’s hall was one of the most famous halls that gathered the distinguished writers and thinkers of the period. Covered secretly by Destouches, Jean entered College Mazarin at the age of 12 and soon assumed the name d’Alembert. Returning to her foster mother’s home after graduating from college, d’Alembert never accepted Madame de Tencin, who later wanted to take him in, as her mother, and lived a very simple life with the Rousseaus until the age of 50. One of the two women D’Alembert cared about throughout his life was his spiritual mother, and the other was the writer Julie de Lespinasse. Julie de Lespinasse took care of d’Alembert, who had a very serious illness in 1765, and the unwavering friendship between them lasted until Julie de Lespinasse died in 1776.

Joining the members of the French Academy in 1754, d’Alembert was appointed permanent secretary of the organization in 1772. d’Alembert, who played an active role in Diderot’s great Encyclopedia attempt for about thirteen years, starting in 1745, left the Encyclopedia in 1758 because of an article that made a big noise, and he placed all his hopes on the Academy. However, despite all his efforts, no important work came out of the Academy during this period. D’Alembert lived more and more despairing day by day. Many of the ‘philosophes’ had died, his old ties with Diderot had been severed, and the death of his thirty-year-old friend Voltaire in 1778 had shaken him deeply. The correspondence of d’Alembert and Voltaire, who died at the age of 66 in Paris on October 29, 1783, was later compiled and published by Condorcet.

Although D’Alembert received a law degree in 1738, he did not intend to practice law and was very interested in medical sciences. However, less than a year later, he realized that his true inclination was mathematics and he directed all his efforts to this field. The French Academy of Sciences, where he presented his two treatises on the integral calculation in 1739 and the motion of solids in fluids in 1741, accepted d’Alembert1 as a member that year. Publishing his book Traite de Dynamique (“A Study of Dynamics”) in 1743, in which he explained his famous theorem, known as the “d’Alembert principle” in mechanics, d’Alembert applied this principle to fluids the following year, and introduced a new approach to this subject, which had been studied by geometrical methods until then brought. His treatise Theorie Generale des Vents (“The General Theory of the Winds”), published in 1745, opened the doors to the Berlin Academy of Sciences. D’Alembert wrote this work to King of Prussia II, who tried to persuade him to stay in Berlin. He presented it to Friedrich. Although d’Alembert was offered the Presidency of the Berlin Academy many times until his last visit in 1763, d’Alembert always turned down these offers.

Born in Paris, d’Alembert is the illegitimate child of the writer Claudine Guérin de Tencin and the artillery officer, the knight Louis-Camus Destouches. Destouches was out of the country when d’Alembert’s was born, and a few days after he was born, his mother dropped him off on the steps of the church of Saint-Jean-le-Rond de Paris. According to tradition, it was named after the patron saint of the church. D’Alembert was given to an orphanage, but was soon adopted by a glazier’s wife. Destouches secretly paid for Jean le Rond’s education, but did not want his paternity to be officially recognized.

He is a famous scientist who worked on the number of pi in his youth. He is also the inventor of the ratio test. He is the inventor of the nonexistent “centrifugal” force for dynamic equality. This method provides a lot of convenience when performing acceleration calculations in moving objects.

D’Alembert was a regular at some of the salons of the period in Paris, especially the salons of Marie Thérèse Rodet Geoffrin, Marquise du Deffand and Julie de Lespinasse. In addition, he fell in love with Mademoiselle de Lespinasse, and as a result, they began to live together.

He suffered from health problems for many years, and his death was due to a bladder disorder. Known as a non-believer, D’Alembert was buried in an ordinary and nameless grave.


Traite de dynamique, 1743, (“A Study of Dynamics”); Traite de l’equilibre et du mouve-ment des fluides,\744, (“A Study on Equilibrium and the Motion of Fluids”); theory generale