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John Harrison (3 April [ O.S. 24 March] 1693 – 24 March 1776) was an English carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the problem of calculating longitude while at sea. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel.
Chronometer circa 1844-1860. A marine chronometer is a precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation. It is used to determine longitude by comparing Greenwich Mean Time (GMT), and the time at the current location found from observations of celestial bodies.
Early versions erred by less than one minute per day, and later ones only by 10 seconds, very accurate for their time. Dials that showed minutes and seconds became common after the increase in accuracy made possible by the pendulum clock. Brahe used clocks with minutes and seconds to observe stellar positions. [112]
The 24-hour dial has Roman numerals on the outer band and Hindu–Arabic numerals on the inner one. [ 1 ] The history of watches began in 16th-century Europe, where watches evolved from portable spring-driven clocks, which first appeared in the 15th century. The watch was developed by inventors and engineers from the 16th century to the mid ...
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. In Switzerland, timepieces certified by the Contrôle Officiel Suisse des Chronomètres ( COSC) may be marked as Certified ...
Gallet (ˈgæl.eɪ) is a historic Swiss manufacturer of high-end timepieces for professional, military, sports, racing, and aviation use. Gallet is the world's oldest clock making house with history dating back to Humbertus Gallet, a clock maker who became a citizen of Geneva in 1466. It is one of the oldest continuously operating companies in ...
The watch was an 18-size, full plate design. In 1869, the National Watch Company won "Best Watches, Illinois Manufacture" at the 17th Annual Illinois State Fair, for which it won a silver medal. [3] The company officially changed its name to the Elgin National Watch Company in 1874, as the Elgin name had come into common usage for their watches.
Universal Time ( UT or UT1) is a time standard based on Earth's rotation. [ 1] While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation Angle ...