Thomas Mercer Marine Chronometer 1923 nautical antiques

Nautical antiques and rare this
Superb Marine chronometer by Thomas Mercer 1923 with his cabinet mahogany
Manufacturer for admiralty
Exceptional piece with plate ivory grand prize of Neuchatel
Mechanical model rocket and helical ribbons. It works very well.
More information and photo copy this link other nautical antiques
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Is called marine chronometer, a watch especially for large format to keep the time on boats. The marine chronometer has various features:
1) It is almost always provided with a detent escapement sweep hand and jumped at every half-second.
2) It is equipped with a rocket, special device, responsible for regulating the force of the mainspring.
3) The marine chronometer is mounted on a suspension known as «gimbal» as the compass edge, arranged so that said timer occupies a horizontal position regardless of movement or position of the boat.
Is a high precision instrument that is used in particular to the so-called astro navigation with a sextant.
Some timers are set to sidereal time. The principle of determining longitude is very short, as follows:
The ship leaves port, the timer is set to Greenwich Mean Time, he has also special tables (Knowledge of Time, Nautical Almanac, etc. ). These tables indicate, for each day of the year, time of passage of the sun and certain stars over the meridian of Greenwich.
To determine longitude, the officer in charge to take stock, keep using his stopwatch to time the passage of any star, or sun, with its own meridian. The difference between the time of the passage and the time that the star must pass the meridian of Greenwich, said, hours, minutes and seconds, the difference in longitude between Greenwich and place of observation.
Also employed, navigation, watches smaller format, known as chronometers aboard
Is a centerpiece in a collection of nautical antiques.