File:Backstaff.jpg
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Revision as of 19:30, 25 March 2011 by Sean (talk | contribs) ("The back-staff, also known as the Davis quadrant (called a quadrant because it could measure up to 90º), was the first instrument specifically designed for finding latitude at sea. English explorer John Davis conceived the instrument while on a voyage t)
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"The back-staff, also known as the Davis quadrant (called a quadrant because it could measure up to 90º), was the first instrument specifically designed for finding latitude at sea. English explorer John Davis conceived the instrument while on a voyage to find the Northwest Passage and in 1595 described it in his book The Seamen’s Secrets."
Excerpt by Jeanne Willoz-Egnor from http://www.ion.org/museum/item_view.cfm?cid=6&scid=13&iid=31
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 19:30, 25 March 2011 | | 1,024 × 819 (274 KB) | Sean (talk | contribs) | "The back-staff, also known as the Davis quadrant (called a quadrant because it could measure up to 90º), was the first instrument specifically designed for finding latitude at sea. English explorer John Davis conceived the instrument while on a voyage t |
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