Dating girard perregaux movements

All database entries are submissions to the wristwatch category ("chronometres-bracelet") at the observatory competition.The term chronometer is often wrongly applied to timekeeping instruments fitted with an additional mechanism that may be set in motion by pushbuttons to enable measurement of the duration of an event.Chronometers often included other innovations to increase their efficiency and precision.Hard stones such as diamond, ruby, and sapphire were often used as jewel bearings to decrease friction and wear of the pivots and escapement.A mechanical chronometer is a spring-driven escapement timekeeper, like a watch, but its parts are more massively built.Changes in the elasticity of the Balance Spring caused by variations in temperature are compensated for by devices built into it.These observatory chronometers were then sold to the public for normal usage as wristwatches, and some examples may still be found today.The observatory competitions ended with the advent of the quartz watch movement, in the late 1960s and early 1970s, which generally has superior accuracy at far lesser costs.

The term chronometer was coined by Jeremy Thacker of Beverley, England in 1714, referring to his invention of a clock ensconced in a vacuum chamber.

They were useful only for accuracy competitions, and so never were sold to the public for usage.