Chronometer watch

A chronometer (Ancient Greek: χρονόμετρον, khronómetron, "time measurer") is an extraordinarily accurate mechanical timepiece, with an original focus on the needs of maritime navigation.

Outside Switzerland, equivalent bodies, such as the Japan Chronometer Inspection Institute, have in the past certified timepieces to similar standards, although use of the term has not always been strictly controlled.

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.

The marine chronometer is no longer used as the primary means for navigation at sea, although it is still required as a backup, since radio systems and their associated electronics can fail for a variety of reasons.

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 is often wrongly used by the general public to refer 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.

Hard stones such as diamond, ruby, and sapphire were often used as jewel bearings to decrease friction and wear of the pivots and escapement.

Examples of complications include: Quartz and atomic timepieces have made mechanical chronometers obsolete for time standards used scientifically and/or industrially.