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:
“The quality of the will to power is, precisely, growth. Achievement is its cancellation. To be, the will to power must increase with each fulfillment, making the fulfillment only a step to a further one. The vaster the power gained the vaster the appetite for more.”
—Ursula K. Le Guin (b. 1929)
“Her face had the seamed reserve of the old in this country [Japan]. It was a neighborhood poignantly rich in old ladies.”
—Angela Carter (1940–1992)