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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 ...
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 ...
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]
The first known mural sextant was constructed in Ray, Iran, by Abu-Mahmud al-Khujandi in 994. [1] To measure the obliquity of the ecliptic, al-Khujandī invented a device that he called al-Fakhri sextant (al-suds al Fakhrī), a reference to his patron, Buwayhid ruler, Fakhr al Dawla (976–997).
In 1814, when Dent was just 24 years old, he was becoming well known as a watchmaker and clockmaker of some distinction: in this year he supplied a Standard Astronomical Clock for the Admiralty, and at least one pocket chronometer for the Colonial Office African Expedition. As early as 1814, Dent was making clocks and chronometers on his own ...
The first step in sight reduction is to correct the sextant altitude for various errors and corrections. The instrument may have an error, IC or index correction (see article on adjusting a sextant). Refraction by the atmosphere is corrected for with the aid of a table or calculation and the observer's height of eye above sea level results in a ...
The Pioneer Instrument Company was started by Morris Maxey Titterington and Brice Herbert Goldsborough in Brooklyn, New York in 1919 using patents from the Lawrence Sperry Aircraft Corporation. [2] [3] Charles Herbert Colvin was the president. They specialized in aeronautical instruments including a bubble sextant and the Earth Inductor Compass.