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Re: Cape Belsham
From: Brad Morris
Date: 2017 Feb 10, 03:33 -0500
From: Brad Morris
Date: 2017 Feb 10, 03:33 -0500
Hello David
I have been thinking very hard about Worsley's statement of 24 April. He writes "Long. Of C. Belsham being only approx'tly known to us". I've always taken that to mean that he has the coordinates of Cape Belsham but doesn't know which pile of rocks it is. Your interpretation may differ. I welcome different viewpoints on this matter.
I think it clear that Worsley had access to charts as well as Epitomies, Gazeteers, Ethiopics and the written records of earlier expeditions. It is not one to the exclusion of all others, at least IMHO. Is the meaning "only approx'tly" that the references don't agree? Does it mean that while the references state there really is a Cape Belsham, there is no agreement among them?
Thank you for the Laurie Chart of 1822. In the Laurie chart, Clarence Island is present, as is Elephant Island. The chart shows two discernible features of importance to the conversation. Cape Valentine is the eastern most point of Elephant Island and Cape Belsham is the northern most point. These two capes do appear in numerical form in the references. Most notably, in the Ethiopics wherein Cape Belsham is the "N.point of Elephant Island".
One other assertion may be made. The Laurie chart of Elephant Island looks nothing like the modern representation. Frankly, neither does the Steiner chart of 1912. From this I infer that the charts Worsley had access to are unreliable when it comes to the coupling of named features to physical landmass. The island must not have been adequately surveyed until post expedition. This would be another layer of great uncertainty for Worsley and Cape Belsham.
Which leaves me asking, "Was Worsley the luckiest navigator of all?" After all of the uncertainty in the charts and disagreement among references, he somehow determines the modern coordinates to within a very small margin of error. While Robin and I have disagreed about the numerical value, there is no quibbling about the fact that it is very nearly spot on.
Worsley does adjust the chronometer by another 1m4s (16 arc minutes to the east) on the 28th of April. Worsley must therefore think his Point Wild longitude in error [it was not]. If we take Worsley at his word then instead of 54°50'W, it seems the determination of longitude should have been 54°34'. Differing viewpoints welcome here.
I am unsure if Worsley is puzzled, because of his chronometer rate is in error, unknown to him. Is Worsley mixing the chronometer rate and the Point Wild longitude? Certainly, they are interrelated. Lars and I both independently determined the chronometer rate should have been 11 seconds per day, not 5 as Worsley determined. Yet there is insufficient accumulation of error in only 4 days to account for 16 arc minutes of adjustment.
Brad
