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    Re: Sextant Scope Parallelism (was Re : SNO-T Sextant)
    From: Robert Gainer
    Date: 2004 Aug 13, 00:59 +0000

    Bruce,
    That�s where you got me. If the sextant is vertical you are measuring the
    correct angle. If the scope is pointing off center by a small amount then
    you see the sun a little displaced from the center of the scope. But isn�t
    the sun still in the center of the horizon mirror and therefore in the right
    place for the measurement.  If you insist on keeping the sun in the center
    of the scope I don�t think that you can get the sun to the bottom of the
    arc, it will wander off center as you get to the bottom.  Can you force it
    both to the center of the scope and the bottom of the arc at the same time
    if the scope is out of Parallelism?
    Now more confused,
    Robert Gainer
    
    
    
    >From: Bruce Stark 
    >Reply-To: Navigation Mailing List 
    >To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    >Subject: Re:       Re: Sextant Scope Parallelism (was Re : SNO-T Sextant)
    >Date: Thu, 12 Aug 2004 20:34:05 EDT
    >
    >Robert,
    >
    >In measuring altitudes above the sea horizon, you swing the sextant to sure
    >you've brought the sun, or whatever, down to that part of the horizon
    >directly
    >under it. In other words, you are checking that that the measurement is in
    >a
    >vertical plane, not slaunchways. Being vertical doesn't mean it's parallel
    >to
    >the plane of the instrument.
    >
    >Bruce
    
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