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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 Negus chronometer went with Robert Peary to the North Pole. Another was with Richard E. Byrd at the south Pole. [9] When John Mercer Brooke was on the North Pacific Exploring and Surveying Expedition in 1852, he said the best chronometer on the expedition proved to the one made by T. S. Negus and Company, which was purchased by the government ...
William Walker was born in 1783 and founded a dynasty of watchmakers in St. Helens, Merseyside. [2] His grandson, Thomas Mercer (b. 1822) was apprenticed to him. Thomas’s father, Richard Mercer, was a sailmaker, so Thomas had the horological and the nautical in his career ancestry. The Shackleton Chronometer.
Seiler Instrument & Mfg. Co. is a manufacturer specializing in optical fire control equipment as well as a major distributor of surveying software and instruments, microscopes, and Zeiss planetariums. There are several main divisions within the company which include Manufacturing, Geospatial-Survey, Medical, Seiler Design Solutions, LLC., and ...
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 ...
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 ...
Lewis travels by horseback to St. Louis in present-day Missouri intending to spend the winter procuring more supplies. [24] [25] December 12: Clark arrives at the site of the expedition's winter encampment on the Mississippi River above St. Louis in Illinois. The construction of Camp Dubois begins the next day. [26] [27] December 20
The sextant was derived from the octant in order to provide for the lunar distance method. With the lunar distance method, mariners could determine their longitude accurately. Once chronometer production was established in the late 18th century, the use of the chronometer for accurate determination of longitude was a viable alternative.