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Longitude by chronometer is a method, in navigation, of determining longitude using a marine chronometer, which was developed by John Harrison during the first half of the eighteenth century. It is an astronomical method of calculating the longitude at which a position line, drawn from a sight by sextant of any celestial body, crosses the ...
To find the position of a ship or aircraft by celestial navigation, the navigator measures with a sextant the apparent height of a celestial body above the horizon, and notes the time from a marine chronometer. That height is compared with the height predicted for a trial position; the arcminutes of height difference is how many nautical miles ...
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...
The frame of a sextant is in the shape of a sector which is approximately 1 ⁄ 6 of a circle (60°), [2] hence its name (sextāns, sextantis is the Latin word for "one sixth"). "). Both smaller and larger instruments are (or were) in use: the octant, quintant (or pentant) and the (doubly reflecting) quadrant [3] span sectors of approximately 1 ⁄ 8 of a circle (45°), 1 ⁄ 5 of a circle (72 ...
Marine chronometer used to determine time at the prime meridian with great precision which is necessary when reducing sights in celestial navigation. Nocturnal used to determine apparent local time by viewing the Polaris and its surrounding stars. Ring dial or astronomical ring used to measure the height of a celestial body above the horizon ...
In 1599–1600, Edward Wright's World Chart of 1599 was the first map under the Mercator projection drawn by an Englishman for English navigation. The map prominently displays the Queen Elizabeth I Privy Seal; the only one of her realm to carry her private seal. The Molyneux 1592 globe is the only other cartography with her Privy Seal.
Thomas moved to Liverpool to continue working as a watchmaker in 1843, and thence to London in 1854, to buy a one-way ticket to the USA, in search of new and better prospects. Seeing a chronometer in the window of John Fletcher (chronometer makers), he changed his mind about the USA, asking for work and being hired on the spot. [3]
HPI, LLC, also called HPI, is a limited liability corporation based in Houston, TX specializing in the design and development, engineering, manufacturing, testing, installation, and commissioning of control and monitoring systems for industrial turbo-machinery applications. [1]