To produce a double virgule balance staff- one of the most difficult of all staffs to make for any watch is an art in itself, but to make one for a watch as small as this one requires extraordinary horological skills. Divernois was a master in double virgule escapement who was known for fitting them into miniature repeaters which he then incorporated into ring watches. Tardy reports that he charged between 10 and 20,000 livres for them. Miniaturization in horology began in the 14th century, when table clocks became so small that they could be carried. They looked like 15th century round table clocks but were smaller. This, in course, led to watches, which in the beginning were actually small, wearable clocks. Their popularity grew very quickly. Once the fashion of wearing watches was established, makers rivaled with each other for their miniaturization. Only the best, of course, could fit all the necessary parts in a small area, but some succeeded beyond expectations. By 1518 watchmakers were able to make movements so small that they could be placed within the hilt of a dagger. Some such pieces were made for Francois I of France, for which he paid a small fortune. Approximately fifty years later a watch was placed in a ring for Elizabeth I of England; it also possessed a curious alarm system, which pricked the Queen gently in the finger Breguet used this system in his alarm rings 250 years later. Jean-Henri Divernois One of the best miniature horologists in France, he was born in Geneva and moved to Paris where he became Master in 1773 and established himself first at Rue Dauphine, later, in 1778, at Rue de la Comédie Française. In 1771 he presented to the Académie Royale des Sciences two watches with semi-circular dials and hands that returned to their starting point, and in 1793, a double virgule escapement, as well as a general essay on horology.