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:
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Or race of youthful and unhandled colts
Fetching mad bounds, bellowing and neighing loud,
Which is the hot condition of their blood;
If they but hear perchance a trumpet sound,
Or any air of music touch their ears,
You shall perceive them make a mutual stand,
Their savage eyes turned to a modest gaze
By the sweet power of music.”
—William Shake{peare (1564–1616)
“I do not know what right I have to so much happiness, but rather hold it in reserve till the time of my desert.”
—Henry David Thoreau (1817–1862)