Watch, ca. 1650–60
Movement by Jean Rousseau the Younger (Swiss, 1606–1684)
Case: rock crystal mounted in gilded brass; Dial: silver, with single gilded brass hand; Movement: gilded brass and steel, partly blued; Diam. of back plate 1 5/16 in. (3.3 cm)
Gift of J. Pierpont Morgan, 1917 (17.190.1014)
Constantijn Huygens wrote to his brother, the brilliant mathematician Christiaan Huygens, from Geneva on January 5, 1650, that he had just bought a watch "à la mode" with a case of rock crystal that permitted a view of the movement such as one would see if the case were made of ice. Indeed, Geneva was well-known for its rock crystal watchcases made from a local source of the mineral. The movement of this watch has a verge escapement, and it is probably the product of the younger Jean Rousseau, a son of a master clockmaker in Geneva and the great-grandfather of the philosopher Jean-Jacques Rousseau.