Power Reserve Indicator
Some high grade watches have an extra dial on the face indicating how much power is left in the mainspring, often graduated in hours the watch has left to run. Since both the arbor and the barrel turn, this mechanism requires a differential gear that measures how far the arbor has been turned, compared to the barrel.
Read more about this topic: Mainspring
Famous quotes containing the words power and/or reserve:
“Armies, though always the supporters and tools of absolute power for the time being, are always the destroyers of it too; by frequently changing the hands in which they think proper to lodge it.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“Mutual repect implies discretion and reserve even in love itself; it means preserving as much liberty as possible to those whose life we share. We must distrust our instinct of intervention, for the desire to make one’s own will prevail is often disguised under the mask of solicitude.”
—Henri-Frédéric Amiel (1821–1881)