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    Re: What is the Longest Lunar Possible?
    From: Brad Morris
    Date: 2013 Jan 22, 14:40 -0800

    Hi Geoffrey

    My firewall was preventing any files to uploaded. First I had to realize that was the cause, then I had to determine how to shut it off (temporarily). Most annoying!

    As promised, here is the link to the file describing the optical path of a prismatic reflecting circle. Chauvenet presents this drawing to compare and contrast the prismatic circle to a 'standard' non-prism based reflecting circle. Shown, is the optical path for a 180 degree observation.

    If you wish to read his comments, simply search for 'prismatic reflectng circle' and examine the result from google books. As a cross reference, its a Pistor & Martins circle, which Chauvenet specifically mentions. Indeed, he is describing the instrument I am now the caretaker of!

    Kind Regards

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