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Re: DR by any other name....
From: John Huth
Date: 2010 Dec 31, 10:16 -0500
From: John Huth
Date: 2010 Dec 31, 10:16 -0500
Here's the earliest instance of the term dead reckoning I could find in a cursory Google advanced book search. This is from a publication in 1694 - it's a publication of several journals. This particular passage is from a piece titled "Journal, In His Magesties Ship the Speedwell, Captain John Wood Commander, Bound for the Discover of a Passage to the East-Indies, by the North-East: Sailing about Nova Zembla, and Tartary and so to Japan. 1676."
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Saturday, June 17. From the 16.Noon to this Day Noon, a fresh Gale at West-north-west and West, with Rain and cloudy Weather. Course per Compass North-east, distance sailed by the Log 127 Miles, difference of Lat. 90 Miles, departure East 90 Miles, Lat per Judgment 69 d. 48 m. Meridian distance 303 Miles, but by a good Observation at Noon Lat. 69 d. 53 m difference of Lat. between the Dead Reckoning and Observation is 9 Miles, which imputed to a westerly variation, which is found by an Azimuth 7 d. Meridian distance corrected is 300 Miles; fair Weather.
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I noted the use of "Judgment" many times for what appeared to be synonymous with Dead Reckoning - but I need to read the whole journal to get a sense of the usage.