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Watchmaking Terms

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Term Definition

Invented by Abraham-Louis Breguet in the 17th century, the tourbillon is a rotating cage that houses the escapement, which turns in an anti-clockwise direction to counter the effects of gravity on timing precision. While vital to the accuracy of pocket watches, tourbillons today remain a sought-after complication that tests a watchmaker’s technical prowess.

Vibrations per hour (vph)

This is a unit of measure for the pulse of the watch, i.e. its beat rate. In the case of a mechanical watch, it refers to how many swings/ticks the balance wheel makes in an hour. Older watches tend to have slower beat rates of 18,000 (5 ticks per second) or 21,600 vph (6 ticks per second); today’s watches typically beat at 28,800 vph, and some would be rated at 36,000 vph. Generally, the faster the beat rate, the more accurate the watch, but at the expense of greater mechanical wear and reduced power reserve.