Joseph de Longueil (1730–1792) Mechanical Concert, invented by R. Richard, on display at the King’s Library. 1769. Etching and engraving after Charles Eisen. 252 x 263 [293 x 343 mm]. Portalis and Beraldi 3. A very fine print on laid paper, with the lustre, the flame above the cherub’s head, and the three “&” symbols after the words “du Roy” removed. AABM stamp (Lugt 3075). The work depicts an exceptional musical automaton (a “mechanical concert”) invented by Robert Richard for the Count of Saint-Florentin, Secretary of State for the King’s Household and Minister of State, and presented at the time to the King’s Library (now the Bibliothèque nationale de France, Richelieu branch in Paris). This complex automaton recreates the scene of a period musical salon. High-society spectators could admire three life-size mechanical musicians (a young girl singing and playing the harpsichord, a Spaniard playing the violin, and an abbot playing the bass), as well as a little Cupid who beats time and turns the sheet music, which the three musicians follow with their eyes in real time.