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    Re: lunars hard to shoot?
    From: Bill Murdoch
    Date: 2000 Sep 07, 9:30 PM

    In a message dated 9/7/00 5:54:42 PM Eastern Daylight Time,
    george{at}HUXTABLE.U-NET.COM writes:
    
    > Yet in none of these modern texts that I am aware of will you find
    >  any description, or even any mention, of this second sight-line.
    
    The current edition of "The Navigator's Newsletter" (issue sixty-eight,
    summer 2000) has sketches of an octant used for both fore and back sights
    with both a natural and an artificial horizon.  There is a similar drawing in
    Peter Ifland's "Taking the Stars" on page 89.
    
    A friend of mine bought an ebony octant at an auction earlier this summer.
    It is such a simple thing.  Has anyone tried making one himself ?  How did it
    turn out ?  The optics are all in the Edmund Scientific catalogue.  The ivory
    scale could be duplicated on an overhead projector acetate with a drafting
    program and a laser printer.
    
    How are sextants checked ?  My Freiberger has a table of errors inside the
    case.  How are they determined ?  I can imagine measuring the distance
    between two stars and making the corrections for refraction like a lunar
    measurement, but I can not reproducibly measure arcs to better than 0.2'
    holding the sextant in my hand.  How could I determine the accuracy of a home
    made sextant ?
    
    Bill Murdoch
    

       
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