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:
“Here far from the city we make our roadside stand
And ask for some city money to feel in hand
To try if it will not make our being expand,
And give us the life of the moving-pictures’ promise
That the party in power is said to be keeping from us.”
—Robert Frost (1874–1963)
“We must reserve a back shop all our own, entirely free, in which to establish our real liberty and our principal retreat and solitude.”
—Michel de Montaigne (1533–1592)