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    Re: Transcription of Worsley's Log
    From: Brad Morris
    Date: 2009 Mar 16, 17:58 -0700

    Hi George
    
    Now that I have some confidence in the digits and have the spreadsheet, I can 
    next investigate his chronometer and chronometer error.  On 7May1916, Worsley 
    indicates that his "chron[ometer] was much slower than I had allowed"..  
    While we can only estimate his rate, we can certainly investigate his initial 
    error.
    
    On 24Apr1916, Worsley writes that the longitude of Cape Belsham is his only 
    opportunity of "rating" his chronometer.  The important criteria in this 
    calculation are an exact knowledge of his latitude, longitude, the alitutde 
    of the body and the chronometer reading.
    
    I examined my navigational charts of the Antarctic Penninsula and extracted 
    the position of Cape Belsham.  The chart number is 29104 (NSN 7642014012241) 
    "King George Island to Clarence Island" with Elephant Island smack in the 
    middle of the chart.  Cape Belsham is clearly marked.  I make the latitude to 
    be South 61 degrees 6 minutes 22 seconds and the longitude to be West 54 
    degrees 53 minutes 45 seconds.
    
    Next, I used my spreadsheet to enter exact values.  On 24Apr1916, Worsley 
    writes that his chronometer was slow by 10 minutes 51 seconds and then 
    proceeds to use 24.40.1 as his chronometer reading.  From this we can expect 
    that his chronometer actually read 24.29.10 (+10.51 = 24.40.1).  Using 
    24.29..10; the equation of time for the day 1 minute 53 seconds and the exact 
    latitude, I can vary the chronometer error until the precise longitude is 
    obtained.
    
    To obtain the precise longitude, I must use 13 minutes 28 1/2 seconds.  That 
    is, while Worsley makes his chronometer 11 minutes 55 seconds slow, I am an 
    ADDITIONAL 2 minutes 33 1/2 seconds slower.  
    
    That is a substantial difference, to say the least.  
    
    Best Regards
    Brad
    
    
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