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Robin, et al,

There is one logarithm that indicates that Worsley is using a 6-figure table, but rounding to five figures. That is the last observation on May 7th, where log cos 85°41' is given as 876.62. In a 6-figure table, like Norie's Epitome of 1860, the log is given as 8.876615, which very well could be rounded up to 8.87662. In a 5-figure table it should be given as 8.87661. This is the only instance that I have found with this indication; in two other occasions rounding up of a "five" in the sixth decimal gives correct 5-figure result.

In Norie's Epitome of 1860, there is a 5-figure "Logarithms for finding the Apparent Time or Horary Angle" that, for the "rating" sight of April 24th, with interpolation, gives the time 2^h55^m25^s before noon, or 21^h4^m35^s astronomical time. Using more digits, log sin²(t/2)=9.14437 gives t=2^h55^m24^s. But any 5-figure table would give the same result, so this is no proof ...

This Epitome, the 17th edition of 1860, is the only one that I can find on line. 

It gives "Elephant or Barrow's I. - Cape Valentine" as 61°5'0"S, 54°55'0"W.

Finally, a minor remark: On 29th April there is an entry 57^s, which most probably shall be read as 57°.

Lars