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Hi Henry

After a tremendous amount of typing, I finally saw what you were saying and 
started over.  We agree, Worsley saw his longitude as West 54-50-00 and we 
think, based on modern charts, that the longitude is West 54-53-45.  This 
gives us a delta longitude of 00-03-45.  

So why does my 2.13 not agree with your 1.804?  I used a great circle 
distance, accounting for the difference in latitude as well as the distance 
in longitude.  Your calculation, I believe, accounts only for the DLO.  
Fundamentally, these values are fairly close and not truly worthy of extended 
discusion.  

----------------
This is the point I am trying to drive at, however.  If his observation and 
consequent reduction yields West 54-19-45 and he "knows" West 54-50-00, then 
his DLO is 00-30-15 (arc).  If we convert this arc to time, we should get 2 
minutes 1 second of CE, not 1 minute 4 seconds. This is where I would like a 
bit of help in my understanding. 

I think from your equations of the other day that {you think} he estimates his 
distance to Cape Belsham at 1 minute 4 seconds (time) and therefore he must 
subtract that out from his CE.  That supposes that there are 16 minutes of 
arc to Cape Belsham from Point Wild.  That is very high of the mark.  He can 
see it from Point Wild pretty clearly.  I measure it on my chart 29104 at 
00-01-30 arc. So 1 minute 4 seconds time should really be much lower, or 
roughly 6 seconds time.  

Thats a 58 second delta.  If you read Worsley's note on 7 May 1916, he states 
that he is "about" 20 miles astern due to his CE, on an easterly course.  So 
even Worsley knows his chronometer is slower than he expected.

This can be attributed to (1) Worsley doesn't have a good idea of the rate of 
his chronometer.  (2) Worsley doesn't get the right value for CE on Elephant 
Island.

Which one?  I simply don't know.  I find both outcomes strange.  He should 
know the rate of his chronometer after working with it on this expedition.  
Maybe he just started working with this pocket chronometer after abandoning 
all others on the ice.  He also knows the longitude of Cape Belsham fairly 
well (not to modern values, but not too far off).  


-------------------------------------------
Your calculation was

    Meridian angle  02-55-24.6 East (in time)
                                11-59-60
    LAT         09-04-35.4
    GAT         12-41-54                    Longitude       03-37-18.6 W (time) = 54-19-39 W (arc)
    DLo Cp Belsham      00-01-04.0 W (time) = 00-16-00 W (arc) 
    Calc Lo Cp Belsham  03-38-22.6 W (time) = 54-35-39 W (arc)
    True Lo Cp Belsham  03-39-32.2 W (time) = 54-53-02 W (arc)
    Diff = CE, Slow     00-01-09.6 (time)   = 00-17-23 (arc)

The "Dlo Cp Belsham" is too large.  It should read 00-00-06 W(time)=00-01-30 W (arc).

Another very minor point, the "True Lo Cp Belsham" should read 54-50-00, not 
54-53-02 (thats the modern value).  This would reduce the time downwards from 
00-01-09.6.

---------------------

I do appreciate your time on these points Henry.  It is helping me to get this right!

Best Regards
Brad Morris

 


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