Skip to content
The Encyclopedia of Horology

USA · 1957

Battery-Powered Balance Watch (Hamilton 500)

Partially verified

Proved the market for electric watches, though contact reliability was poor.

A battery energises a coil on the balance, with contact wires switching the current; the first battery-powered wristwatch sold commercially.

How to verify this yourself

Search the relevant national patent office archive (Espacenet covers most European and US specifications) by inventor name and date range; confirm the number from the specification itself, not secondary sources.

Manufacturers known to have used it

  • Hamilton

Diagram

balance wheel with timing screwsflat or overcoil hairspringregulator index
Schematic: balance, hairspring and regulator. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Sources & references

  1. Hamilton Watch Company published history
  2. Reymondin, C. et al., The Theory of Horology

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