Hi Henry
I measure the delta between Point Wild and Cape Belsham, both on Elephant Island, to be 1.5 arcminutes (90 arc seconds) in arc (longitude, not time). This is based upon the modern chart 29104
http://data.aad.gov.au/aadc/mapcat/display_map.cfm?map_id=5823--------------
Worsley's definition of the latitude and longitude of Cape Belsham is directly in front of us. On 24 April 1916, he indicates that the distance made good to noon on 25 April 1916 is NORTH 64 miles. He carefully records his latitude on 25 April as South 60 degrees 0 minutes and his longitude as West 54 degrees 50 minutes. His latitude on 24 April was 61 degrees 4 minutes. Hence we can deduce what he thought his longitude of Cape Belsham.
Worsley's Est of Cape Belsham
South 61 deg 4 minutes West 54 deg 50 min
Modern (Chart 29104) of same
South 61 deg 6 min 22 sec West 54 deg 53 min 45 sec
Displacement between the two
3.43 kilometers (2.13 miles)
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What is terrifically interesting is that Worsley, on 24 April 1916, calculates the longitude at West 54 deg 19 min 45 sec. His estimate of the longitude of Cape Belsham is West 54 deg 50 min. Thus the delta is 30 min 15 sec. By simple conversion formulas, this should be 2 minutes 1 second of time.
Yet he records 1 minute 4 seconds of time. Perhaps he understands just how much trouble he is in when he states "No observation for latitude could be
obtained. Longitude of Cape Belsham is only opportunity of know it is, allow 1 minute 4 second more slow = 11 minute 55 second slow."
This is a 57 second error, using his own estimate of Cape Belsham.
When we inject the modern longitude of Cape Belsham, the error grows.
Best Regards
Brad
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