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    Re: Transcription of Worsley's Log
    From: George Huxtable
    Date: 2009 Mar 5, 17:20 -0000

    A few further notes about Worsley's log pages of the boat journey with 
    Shackleton from Elephant Island to South Georgia in 1916.
    
    Brad has added to his pages of transcription, on website
    http://www.fer3.com/arc/imgx/f1-The-Log.pdf .
    
    Referring to the log for the date 24th April-
    
    Brad's transcription refers to a "break in the xxxxx ice". I wonder if that 
    might be pack ice, possibly brash ice; might either fit?
    
    The time of the observation is given as 24.40 1, which I expect is the GMT, 
    from the chronometer, and we have presumed that the correction for the 
    chronometer being slow by 10 min 51 sec has already been made.
    
    That's an odd way to denote a Greenwich time after Greenwich noon, isn't it? 
    Remember, in those days, the Greenwich day started at Greenwich mean noon, 
    so 0 hrs GMT for 24th April corresponded to noon, halfway through the civil 
    day of  24th April. That was the way Greenwich dates and times were noted in 
    almanacs of that era, recorded in Astronomical Time, which ran 12 hours 
    later than ordinary civil time. To everyone's confusion, though I imagine 
    that navigators had got accustomed to it, and thought it to be the natural 
    and unchangeable order of things.
    
    But it seems odd that Worsley notes a time, 40 minutes after Greenwich noon, 
    as 24.40.01, and not 00.40.01 . I suppose it's no more illogical that our 
    present habit of referring to 40 minutes after noon as 12:40 pm rather than 
    00:40 pm. Perhaps it's the old reluctance to use zero as a number on its 
    own, that I suspect relates to Roman numerals, which were always used on 
    clock dials, and which lacked a symbol for zero. Presumably, for Worsley the 
    GMT, twenty minutes later, would suddenly change from 24.59.59 to 01.00.00.
    
    Anyway, it's convenient that the time has in that way been enhanced by 24 
    hours, because it then makes it simpler to subtract from it the Local 
    Apparent Time of 21 hrs 04 min 35 sec, derived from the observation of the 
    Sun.
    
    From the difference between Greenwich Apparent Time, 24 hrs 41 min 54 sec, 
    and that Local Apparent Time, Worsley deduced the longitude of his 
    observation point to be 54� 19' 45" West, but that depends on the value 
    assumed for chronometer error, 10 min 51 sec, being correct. If it was, that 
    longitude would correspond with the longitude of his observation point. He 
    doesn't tell us, on that page, what value he has taken for the longitude of 
    Wild Camp; does he do so elsewhere, I wonder? Perhaps we can work it 
    backwards, from that deduced longitude, and the correction he found it 
    necessary to make to the chronometer, of 64 sec of time. That implies a 
    change of 16' of longitude, which means, if I've applied it in the right 
    diection, that Worsley thought his true longitude, at Wild camp, to be 54� 
    45' 45".
    
    Now I have received a copy of the Geographical Journal for September 1972, 
    with a nice report of a British Joint Services expedition to Elephant Island 
    in 1970, with a superbly detailed fold-out contoured map and claiming 
    accurate survey. That confirms, pretty well, the latitude of Wild Camp that 
    I suggested in a previous posting as 61� 08' S (though now I would revise my 
    estimate to 61� 07') and which Worsley had taken to be 61� 04'. And that map 
    provides a true longitude of 54� 52' for the camp, 6 miles further West that 
    Worsley seems to have thought it was. That wouldn't, in itself, be a great 
    surprise. I doubt whether such obscure Antarctic islands had been systematic 
    surveyed with any great accuracy, especially for longitude.
    
    So if he had a modern value for the longitude of Wild camp, then he would 
    have increased his chronometer error by another 24 sec to adjust for that 
    extra 6 miles, to make the chronometer error on that day 12 min 19 sec, not 
    11 min 55 sec. Then that would increase by 5 sec per day, as before.
    
    If Worsley was setting off with such an discrepancy in his initial 
    longitude, affecting has assessment of chronometer error, that would stay 
    with him all the way to South Georgia. Not Worsley's fault, and there was 
    nothing he could do to fix it. When he admitted to Shackleton, nearing South 
    Georgia, that he couldn't be sure of his position to within 10 miles, quite 
    a lot of that error must have been inbuilt from the start.
    
    George.
    
    contact George Huxtable, at  george{at}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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