Mystery Clocks The ?Pendules Mystérieuses?, or Mystery Clocks, were Cartier's masterpieces, the result of the collaboration of Louis Cartier, his principal creative advisors, and the technical skill of Maurice Couët. These clocks were developed after a careful study of those created by Robert-Houdin, the French magician and clockmaker (1805-1871). Couët was 28 years old when he brought his ?mysterious? clock creation to Cartier. The fascination of Couët's invention is based on the principal of an optical illusion. Couët's first mystery clock relied on a lateral double-axle system. In 1920, he devised another model using a single, central axle and subsequently, both methods were used. The mystery is in that the hands that appear to float in space without any connection to the movement, when in fact they are each fixed onto a separate crystal disc. These discs are each surrounded by a tooth-edged border and driven by worm screws fixed at the ends of the two lateral axles, working at the levels of 9 and 3 o'clock, invisibly concealed within the frame. The rotation of the axles is activated by the movement hidden in the base. Therefore, it is not the hands which move but each disc on which they are individually fixed, at two different speeds, one for the hours and one for the minutes.