Ships Clock "Chronometer"


Above: A Chronometer

A chronometer is a navigational tool used on sailing vessels to measure accurately the time of a known fixed location in order to determine the ship's longitude. The angle between the sun and the horizon (or if taking a reading by night the angle of the stars above the horizon) determines the latitude - a measurement taken by a sextant - another navigational tool, but longitude is a more difficult measurement.

To determine longitude the navigator needs to know the time difference between where they are standing and some other fixed point. In an hour the earth will rotate 15 degrees (360 degrees every 24 hrs) so if the time difference between you and a fixed point is 2 hrs, then you know that you are 30 degrees east or west of that point. In 1884 Greenwich, England became the official Meridian Line for all points around the glove and GTM (Greenwich Mean Time) became the official time for the entire world...

On knowing the latitude and longitude the navigator then goes to his nautical charts and using his parallel rule can pin point his exact position.

The chronometer in the picture above was used by Capt. James Mustard of Cardigan Head, P.E.I. who sailed vessels built in Cardigan. It was refurbished by his grand nephew, John Mustard, who has given permission for its display at the Cardigan River Heritage Center, where it is still located to this day.

All of the information on this page was given to us courtesy of the
Cardigan River Heritage Center which is Located at
4537 Wharf Road
Cardigan, P.E.I.

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