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    Re: Bygrave position line slide rule
    From: Zvi Doron
    Date: 2004 Feb 29, 09:00 -0000

    Hi Dan
    Thanks for that - the Otis King is British made to the best of my knowldge.
    It has chrome scales and a black handle, two models were make, the K and the
    L, with different scale sets. They appear from time to time on eBay UK, the
    better deals have the instructtions and the box. They can fetch somewhere
    between 30-100 GBP.
    Excellent scans of one of these can be seen on the website of Mr. Atsushi
    Tomozawa of Japan.
    You can also download instructions from the following website to understand
    how to operate one.
    The Bygrave has a roughly similar mechanical construction ()according to the
    one drawing I have) but the scales are dedicated to a two step process of
    solving the PZX triangle.
    Kind regards
    > I found one thing from Google:
    > http://home.ecn.ab.ca/~jsavard/other/sr03.htm
    > The Otis King Slide Rule
    > This slide rule consists of a body with a helical scale, on which a sleeve
    > with a similar helical scale could both slide and rotate. An outer sleeve
    > then slid and rotated on that sleeve at one end, and at the other end was
    > constricted to slide directly on the body. Marks at the two ends of that
    > sleeve constituted the cursor of the slide rule; thus, instead of placing
    > the two helical scales in coincidence, points on the two scales separated
    > the distance between the two cursor marks were treated as corresponding.
    > The Otis King cylindrical slide rule was perhaps the most popular and
    > inexpensive circular slide rule made.
    > A special-purpose cylindrical slide rule made for use in sight reduction
    > celestial navigation, the Bygrave position-line slide rule, was based on
    > same principle.
    > ---
    > As a mathematician, I simply turned your problem into a different one:
    > the heck is an Otis King slide rule?  Sounds very interesting!
    > Dan

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