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Brad Morris wrote, about Worsley's determination of chronometer error at
Elephant Island-

"Secondly, neither George nor myself can establish with absolute certainty
where he took his observation.  Point Wild is an assumption.  It makes
logical sense, as, from their own accounts, it was very difficult to move
over land in the Antarctic.  Point Wild was the location of the camp.  Most
likely the observation was there but agreed, we can't prove it."

On the contrary, there's little doubt about it, for these reasons-

1.. All around are high cliffs. Wild Camp was the only spot around where
there was any sort of beach. To determine the dip involved in a Sun
altitude, it has to be taken from a height above sea level that's accurately
known. Observations from other points, such as Cape Belsham, would not have
been possible, for that reason alone.

2. Elephant Island is far more rugged an environment than most of us have
ever had the misfortune to get into. To visit the next headland, the
precipitous Cape Belsham, that morning, before departing around noon, would
call for crossing a crevassed glacier nearly a mile wide, then a couple of
miles of mountain ridge which, if wasn't snow-covered, that was only because
it was all too steep for snow to cling to. And then back. To what purpose?

3. They had their hands full in preparing and loading the Caird, that
morning,and would not have been looking for any such diversions. They had a
beach at hand which faced the morning Sun. I don't see that there's any
question about the matter.

==================

Finally, I suggest that we may be getting a bit preoccupied with this
Elephant-Island chronometer-setting question, which plays only a minor part
in the overall navigation, though an interesting part nevertheless. We're
discussing what appears to be an error in time in his checking of the
chronometer, the result of  imperfect knowledge of the local geography. Each
minute of time error translates to an error in longitude, throughout the
rest of the journey, of 15 minutes of arc, or about 7 to 8 miles, depending
on latitude. After the end of the journey, Worsley assessed that his
chronometer had been slower that he thought, enough to set him back about 20
miles on his expected position. Position errors at setout may be enough to
explain a significant part of this discrepancy, it appears.

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.


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