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    Re: Testing sextant arc error
    From: Bill B
    Date: 2017 Jan 20, 05:21 -0500

    On 1/20/2017 3:58 AM, Bill Lion heart wrote:
    > Suppose you got a 30m room and a ruler calibrared in mm at one end. Then
    > point a well collimated laser from one end of the ruler to the mirror on
    > the sextant (horizontal on a table) so reflected a spot on the ruler.
    > 1mm would be approx 0.1 minute. Take the average either side of the dot
    > and use arc tan on your calculator. Depending on the length of the ruler
    > do the full arc in several stages.
    > Would that work?
    Good thinking. A decade or so ago Frank proposed a method with a
    sextant, simple laser pointer, a table and a long hallway. Besides
    mirror alignment, errors along the arc and collimation there are other
    ghosts in the machine. Eccentricity of the micrometer drum being one of
    them. Frank also devised a test for eccentricity.
    Frank has presented several inventive and creative tests for all of the
    above a decade or so ago (to present), many of which Alex and I pursued.
    Based on his recent posts, I feel confident Frank has not lost his
    intellect, memory--or wry sense of humor. I'm feel confident he can
    direct you to the archived articles if he so chooses.
    Regarding a wry sense of humor: An "outrageous" hyperlink/click-on in
    one of his posts to a URL of an article on outrageous click-ons and
    psychological evaluations was not lost on me. But more than the, "One
    step from traditional navigation" limit? ;-)

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