maurice-quentin-de-la-tour

Marie Josèphe of Saxony, Dauphine of France. Maurice Quentin de La Tour (French, 1704-1788). Pastel on canvas. Gemäldegalerie Alte Meister, Dresden.

Maria Josepha of Saxony (1731-1767) became Dauphine at the age of fifteen through her marriage to Louis de France, the son and heir of Louis XV. Marie Josèphe was the mother of three kings of France, including Louis XVI, who died under the guillotine during the French Revolution. Her youngest daughter, Madame Élisabeth, also was beheaded during the Revolution.

Jean-Baptiste le Rond d'Alembert 

(6 November 1717 – 29 October 1783) was a French 

mathematician

mechanician

physicist

philosopher

, and 

music theorist

. Until 1759 he was also co-editor with 

Denis Diderot

of the 

EncyclopédieD'Alembert’s formula for obtaining solutions to the wave equation is named after him. The wave equation is sometimes referred to as d'Alembert’s equation.