Jumping-hour watches
References in the Grail Atlas catalog carrying the jumping-hour complication.
A jumping hour replaces the hour hand with an instantaneous-changing disc visible through an aperture, while minutes continue on a central hand. The complication dates to early 20th-century pocket watches; modern wristwatch references include the F.P. Journe Vagabondage III, the De Bethune DB28 Maxichrono variants, and the more accessible Chr. Ward Bel Canto Jumping Hour. The hour jump itself is mechanically demanding, done poorly, the disc creeps rather than jumps.
An instantaneous-jumping hour display stores energy over the course of an hour and releases it in a single snapping motion, advancing a numeral disc one position at the exact hour.
How the jumping hour works: history, mechanism, parts required, and what makes it hard to build →
