The art of illusion fascinates adults and children alike. We are all spellbound when magicians deceive the eye with slight of hand and deft trickery, believing they achieve the impossible while knowing perfectly well that it is just magic. Maurice Couët, whose knowledge in the trade was matched by few, perfected the art of illusion in the mystery clocks that Cartier offered, beginning in 1913 with the Model A. Based on the 'pendules mystérieuses' from the 19th century, a selection of which was exhibited at the 1878 Exposition Universelle in Paris, the mechanism of these clocks is hidden in the frame so that the hands seem to float in space without any connection to the movement. Rather than moving by conventional clockmaking techniques, the hands are set into two rotating crystal discs with toothed metal rims that are propelled by gears in the clock case.

Since every part of the clock was hand-made, each one took from three to twelve months to finish; employing not only the watchmaker but also the designer, the 'orfèvre-boîtier', the enameler, the lapidary, the setter, the engraver and the polisher.

However, not only were these mystery clocks an astonishing technical achievement but they were also of extraordinarily imaginative design as best showcased in the 'Le Ciel' mystery clock offered here.