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Re: How good were chronometers?
From: Greg B
Date: 2006 Mar 9, 15:54 -0500
From: Greg B
Date: 2006 Mar 9, 15:54 -0500
Hi Jim, You wrote: ?Was Summner a bit of an exception in relying on his chronometer and subsequently the that first LOP?? I Reply: I have been wondering about that myself. I don?t think it was so much a question him being an exception, if previous experience had found that his chronometer was trustworthy, why not rely on it? The thing that really jumped out at me in the Summner story (that I read) was that he must have been pretty desperate to have even considered pre-calculating the points which he subsequently discovered made up what we now call a LOP! I know there are brighter bulbs then me out there (maybe I got this part all wrong) but wasn?t the standard practice of the day to do either: 1. Do a simple noon sun shoot for Lat & Lon? 2. If you couldn?t do a noon sun shoot for some reason say a high cloud deck, then you would try a equal alt. ( 2-4 hr before and after) shoot. And interpolate local noon? 3. If you were really good at the math, and had favorable conditions; a twilight (morning or evening) sight of Polaris and another star, then work a full spherical triangle? Did I get that right? (If I didn?t please feel free to correct me) If I did, then I see no other reason save desperation for Summner to do what he did, (including relying on his chronometer) I think he thought he was dangerously close to a lee shore which was also rocky (I know that would do it for me). Regards, Greg -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.com/ .