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:
“... whilst you are proclaiming peace and good will to men, Emancipating all Nations, you insist upon retaining absolute power over wives. But you must remember that Arbitrary power is like most other things which are very hard, very liable to be broken—and notwithstanding all your wise Laws and Maxims we have it in our power not only to free ourselves but to subdue our Masters, and without violence throw both your natural and legal authority at our feet ...”
—Abigail Adams (1744–1818)
“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)