The prism clock is a Cartier clock type from the 1930s, distinct from the firm's five mystery clock groups. Like the mystery clocks and the earlier comet clocks, it played on an illusion to astound its viewers, but the mechanism was fundamentally different. Where the mystery clocks used transparent rock crystal discs to make the hands appear to float, the prism clock used a configuration of internal mirrors to reflect a hidden dial.
Mechanism
The prism clock was inspired by the underwater periscope, which uses a configuration of mirrors to see above the water's surface. The prism clock relied on the same principle of reflections: when looked at from the front, the clock clearly told the time, thanks to a series of mirrors that reflected the hidden dial to the viewer's eyeline. When viewed from the back, the clock did not appear to be a clock at all; one could see right through it.
Gaston Cusin
The prism clock was patented by Gaston Cusin (1897-1986), a protege of Maurice Couet. Cusin worked in Couet's dedicated Cartier clock workshop alongside Couet's younger brother Rene Couet (1896-1982), the designer Alfred Louquet (1884-1967), and Alexander Diringer (1893-1982). The patent for the prism clock is documented in the book's endnotes.
Sources
- Francesca Cartier Brickell, The Cartiers (Ballantine Books, 2019), pp. 338-39, endnote 563n100
