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    Re: ? ? ? Re: Dip uncertainty
    From: Bruce Stark
    Date: 2004 Dec 6, 19:06 EST
    Alex,

    You said: "Its another matter that from 20 miles, no matter how powerful
    your scope is (and assuming ideally transparent atmosphere,
    better no atmosphere at all) you will not be able to see the horizon
    THROUGH your prism. What you will see is some spot of the sea surface
    near the prism."

    I realized, too late, that instead of a prism I should have specified a plate of glass with just enough difference in parallelism of surfaces so that a ray coming from the horizon (say 2' below horizontal) would be bent down 2' in passing through it, and come out of the glass horizontal to the earth at that point. At the buoy, looking through the glass, you'd see the horizon 2' above its true place. Looking through the glass from 20 miles away you'd see the horizon very close to its true place.

    Bruce
       
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