Mysterious (watch or clock)

A system patented in 1808 by John Schmidt of St-Mary Axe which uses transparent crystal discs with serrated edges to carry the hands. These discs are driven by pinions, concealed inside the case frame. The movement is usually housed in the base of clocks.

The magician and illusionist Jean-EugËne Robert-Houdin (1805-1871) is also considered to be one of the inventors of the mysterious clock.

Niello A product containing lead, copper, silver, sulphur and sal ammoniac. Niello is applied as a paste over incised gold or silver and then fired in the enamellist's furnace. Excess niello is filed off and the surface smoothed. Polished niello cases were fashionable shortly before wristwatches were introduced.