A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2009 Mar 20, 15:26 -0400
Thank you very much for your independent confirmation of George’s original assessment of the issue. The methodology is now un-disputed! There are some very minor discrepancies in values which attract my attention.
When Worsley writes down his polar distance, he gets 102 degrees 51 ½ minutes. We can subtract the 90 degrees for the South Pole, leaving a North Declination of 12 degrees 51 ½ minutes. This is marginally different from the value you used to determine his GAT in part one of your equations of 12 degrees 51 minutes 17 seconds (for a difference of 13 seconds). I wonder why Worsley would have disregarded the more accurate answer you have provided?
In part two of your explanation, we have exact agreement across the board. We all get precisely the same logarithmic values. The sum of the four logarithmic values is also the same. However, when Worsley looks up (and I calculate) the arc-Haversine of 9.14437, we both get time values of 21-4-36, while you obtain 9-4-35.4. This is due to rounding on my part, if the resolution is extended I obtain 35.51. I think this just noise at the truncation point of the logarithmic values (5 places, 6 places, etc). My question is more basic. Worsley writes down 21-4-36, rounding off to a whole second. Would that be prudent for the purposes of determination of chronometer error in his day? Didn’t the arc-Haversine tables show only the nearest second?
George and I now concur that Worsley must have taken his observation from Point Wild, which on modern charts is South 61 degrees 5 minutes 22 seconds West 54 degrees 53 minutes 45 seconds. Worsley used the location of Cape Belsham. I think he did this because it is so very close by to Point Wild and because Cape Belsham is listed in some tables as the northernmost point of Elephant Island. Of course, his tables or charts may have suffered from the difficulty of ascertaining lat lon, in his day, in the polar regions.
I hadn't intended posting my recap of Worsley's Time Sight quite so soon, as I am still working on the CE portion. However, as you have broached the subject, I post the attachment as a work in progress. Please note that, based on the figures and assumptions available, his calculation is correct, From here forward much, if not all, depends on the Longitude of Cape Belsham that he used.
I hope that the formating is no destroyed in transmission. More to follow.
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