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    Re: Ball Recording Sextant Mark 1 Mod. 0
    From: Paul Hirose
    Date: 2008 Mar 19, 19:51 -0700

    In 1949 the U.S. Civil Aeronautics Administration published a report on
    a ball drop sextant constructed at the U.S. Naval Observatory. They
    tested it in flight against a bubble sextant. The ball drop sextant
    performed poorly.
    You can get a PDF scan (1.2 MB) of the original report online at the DOT
    archive site: http://dotlibrary.specialcollection.net/
    Look for the section with CAA Technical Development Reports. There are a
    lot of reports on that page; use your browser's Search feature to find
    the word "ball". (I've never figured out how to create a link to a
    specific page on this site, probably due to the way they use Javascript.)
    Many papers here deal with the old 4-course radio range system for air
    navigation, as well as the early development of VOR and ILS.
    If you're interested in old time railroading, don't miss the huge trove
    of Interstate Commerce Commission accident reports going back to 1911.
    I block messages that contain attachments or HTML.
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