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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: ? ? ? Re: Dip uncertainty
From: Alexandre Eremenko
Date: 2004 Dec 6, 12:54 -0500
From: Alexandre Eremenko
Date: 2004 Dec 6, 12:54 -0500
Bruce, I find George's argument more convincing. Let me try to rephrase it in a short and more abstract form. Consider two observers, one of height h (small) another of height H (large). Let L be the line from the eye of H, tangent to the sphere, that is the line from her eye to her horizon. Now we can place the shorter observer h so that his line from his eye to his horizon is a PART of the line L. Then whatever uncertainty in the dip h experiences will also affect the H's sight PLUS H will have additional uncertainty which comes from the additional segment of L from h's eye to H's eye. I like this argument very much because of its very general character. (No particular low of refraction is assumed here). Alex. On Mon, 6 Dec 2004, Bruce Stark wrote: > Thanks, Alex, > > I hope people will continue to look for more information. The crux of my > argument, which I don't think has been addressed yet, was in the last paragraph: > > "Set a prism between you and a line on the wall. Put the prism near the wall > and look at the line from across the room. You'll see the line not far from > its true position. Bring the prism close to your eye and you'll see the line a > considerable distance out of place." > > Bruce >