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The Encyclopedia of Horology

Watch family · Complication

Jump Hour Watches

Partially verified

Watches displaying the hour on a numbered disc seen through an aperture, jumping instantaneously to the next number on the hour, rather than via a conventional hour hand.

Movement & mechanism

  • A twelve-position hour disc advanced by a jumper spring that is tensioned throughout the hour and released instantaneously at its end
  • Minutes typically still shown conventionally by a hand or a separate disc
  • Requires more precise energy management than a simple continuously-rotating hour hand, to achieve a clean instantaneous jump

Identification

  • An aperture (rather than a hand) displaying the hour numeral
  • A distinctly 'digital' looking dial layout despite being fully mechanical

Terminology

  • Jumper spring — the mechanism storing and then releasing energy to snap the hour disc forward instantaneously
  • Digital display (mechanical) — a jump-hour or similar aperture-based display, as opposed to hands

Known variations

  • Single jump hour (hour only)
  • Jump hour combined with jumping minutes ('digital' style)

Pocket-watch ancestry

Jump hour (and jump/wandering hour) mechanisms were devised for pocket watches in the late nineteenth century; their most celebrated wristwatch expressions came during the Art Deco period, directly adapting the earlier pocket-watch jumper mechanism.

Collecting notes

Art Deco-era jump hour wristwatches are a distinct and stylistically celebrated collecting niche, valued for their design as much as their mechanism.

Related photographs

Prim mechanical wrist watch disassembled part 1
Prim mechanical wrist watch disassembled part 1 — Kozuch, CC BY-SA 3.0. Wikimedia Commons file page
Prim mechanical wrist watch disassembled part 2
Prim mechanical wrist watch disassembled part 2 — Kozuch, CC BY-SA 3.0. Wikimedia Commons file page
Mechanical wristwatch
Mechanical wristwatch — Petar Milošević, CC BY-SA 3.0. Wikimedia Commons file page

No confidently matched photograph of this subject has been found yet. These photographs show a closely related record, and are not examples of the type described on this page.

Sources & references

  1. General literature on jump-hour and wandering-hour complications; precise originating patents require further research.

Where sources disagree, the disagreement is stated rather than resolved silently.