NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Antoine Couëtte
Date: 2012 Feb 16, 07:44 -0800
Hello Greg,
This table obviously gives differences (in elapsed Mean Time) between Mean and Sidereal Times, with Mean Time running 360° (24 hours) in one "usual day" while Sidereal Time covers the same 360° (again : 24 hours) in just 24 hours of Mean Time minus (some) 4 minutes of our usual Mean Time.
I would suspect that Sidereal Time was then published only once a day for 00h00m00.0s (Greenwhich) Mean Time. Therefore, WITH MEAN TIME AS AN ARGUMENT, this table was probably used to compute the Sidereal Time value by simply adding to the "elapsed mean Time Value from 00h (G)MT " the "add up correction" as defined here-above.
In those days, apparently Navigators used an "Hour, Minute and Second" scale to reckon angular values and variations, while to-day we feel (much) more comfortable with a "(decimal or hexadecimal) Degree" scale to reckon such parameters.
Just a guess ...
Kermit
Antoine M. "Kermit" Couëtte
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