Joseph Lagrange

Joseph-Louis Lagrange, born on January 25, 1736, was an Enlightenment era mathematician and astronomer. Notable for his contributions to celestial mechanics, and having created a celestial coordinate system known as the Lagrangian point system, he spent the first 30 years of his life in Turin, Italy, before working for the Berlin Academy from 1766 and 1787, and then spending the final 26 years of his life in Paris before his death in 1813.

Lagrange's father held charge of the Italian king's military chest in Turin at the time, and had planned for his son to become a lawyer, which he first accepted wholeheartedly. He studied at Turin College, where he found Greek mathematics to be quite dull. However, at the age of 17, he accidentally stumbled upon a paper by Edmond Halley, who inspired a pursuit of mathematics for the young Lagrange. After only a year of study, he was appointed an assistant professor of mathematics at the Royal Military Academy of the Practice of Artillery in 1755 to teach calculus to an army testing ballistics theories of the time, technically making him the first person to ever teach calculus in an engineering school.

During his time at Turin, Lagrange established a society that became known as the Turin Academy of Sciences, where he discussed with pupils and colleagues scientific theorems of the time. Discourse in the society led to a 5 volume work known as the Miscellanea Taurinensia, in which most of his early findings on calculus and celestial movement. In his third and fourth volumes, he expounds upon differential equations of motion for three celestial bodies and effectively explains the Moon's libration.

Leonhard Euler, one of the men whose theorems Lagrange taught in the Royal Military Academy of the Practice of Artillery, saw his raw mathematical talent and attempted to persuade him to come to Berlin, but he had no such intention- it was implied that Lagrange had a distaste for Euler and his theories. He was eventually convinced by Frederick of Prussia to come and be the resident mathematician of his court, asking to have "the greatest mathematician in Europe" in his court. In 1766, Lagrange began his stay in Berlin, where he completed his greatest work- the Mécanique analytique- a further expounding on mechanics and calculus. Following his wife's death in 1783 and the death of Frederick II, Berlin became less feasible of a living option for Lagrange.

After weighing offers from the royal courts of Spain and Naples since 1786, he eventually accepted an invitation from Louis XVI to come to Paris in 1792. He was immediately awarded marks of distinction, special apartments in the Louvre, and membership into the French Academy of Sciences, which became part of the Institut de France in 1795. During the Reign of Terror, a decree was issued that all foreigners were to leave France- but Lagrange was explicitly exempted from that decree. In fact, upon the beginning of Napoleon's reign, in 1799, Lagrange was appointed a Senator by Napoleon himself. After two short teaching stays in the École normale, which only existed in 4 months, and the École Polytechnique, where he was appointed professor of mathematics, he spent the remainder of his days revising the Méchanique analytique. He completed about 2/3 of his revision before his death on April 10, 1813.