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:
“Caring for children is a dance between setting appropriate limits as caretakers and avoiding unnecessary power struggles that result in unhappiness.”
—Charlotte Davis Kasl (20th century)
“In a democracy—even if it is a so-called democracy like our white-élitist one—the greatest veneration one can show the rule of law is to keep a watch on it, and to reserve the right to judge unjust laws and the subversion of the function of the law by the power of the state. That vigilance is the most important proof of respect for the law.”
—Nadine Gordimer (b. 1923)