TJTucson1's Mariner's Quadrant Geocoin
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Owner:
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TJTucson1
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Released:
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Monday, March 21, 2011
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Origin:
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Arizona, United States
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Recently Spotted:
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The quadrant is a very simple instrument of medieval origin used to determine the altitude of a heavenly body. It takes it name from its shape, which is a quarter of a circle. The curved edge is divided from 0 to 90 degrees. At the apex is a right angle, where a cord with a small weight, or plumb-bob, of lead or brass is attached. Along one straight edge are mounted two upright pieces with holes for sighting. When in use, the quadrant is held vertically so the plumb-line falls across the scale of degree markings, and from this the angle of elevation can be read.
Mariners would line the sights of the quadrant up with
Polaris (the North Star) located directly over the North Pole. Because of its location, Polaris never sets like the other stars in the night sky. Lining the star up in the quadrant’s sights, navigators could determine their atitude by measuring the angle (or elevation) between the horizon and Polaris.
South of the equator, where the North Star is not visible,
mariners would use the constellation known as the Southern Cross to determine their southern latitude. Located almost directly above the South Pole, the Southern Cross also never sets. Following the same steps used with the North Star, navigators would measure the angle of levation between the horizon and the Southern Cross to determine their latitude. Although the sun could have been used to measure latitude as well, doing so would have blinded the navigator over time.
This coin can only be discovered in TJTucson1's collection.
Tracking History (4599.6mi) View Map