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    Height Correction
    From: Robert Swartz
    Date: 2020 May 6, 20:19 -0700

    Needed a formula or table to correct for height of instrument above natural horizon. I use the natural horizon of Lake Michigan as a zero reference wnen adjusting bubble sextants.

    On a clear, calm day, the line of the horizon is used to bisect the bubble when the sextant is set to 0 deg./0 min.This then is the zero of the instrument.To eliminate any height of eye error,

    I go down to the the shore as close  as possible to the water--usually 1-2 feet above water level.This is where I work. I find it much easier than using my Link Sextant Collimator which I have to use in

    total darkness in my basement and chase a point source light in the sextant optics.

    Robert Swartz

    Ph. 773-330-0860

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