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    Re: Sextant and quintant limits
    From: George Huxtable
    Date: 2008 Dec 26, 09:55 -0000

    The plates of those Phil. Mag. issues are collected together at the end of
    the voume (sometimes, at the beginning); not with the text.
    The drawings that Richard Pisko didn't find are on page 483. That's the
    Google-page number, which doesn't usually quite accord with the printed
    number of each page.
    contact George Huxtable, at  george@hux.me.uk
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    ----- Original Message -----
    From: "Richard M. Pisko" 
    Sent: Friday, December 26, 2008 6:31 AM
    Subject: [NavList 6829] Re: Sextant and quintant limits
    On Sat, 20 Dec 2008 12:33:05 -0700, George Huxtable 
    >  "Douglas reflecting protractor". (Note, this shouldn't be
    > confused with the modern Douglas Protractor, a transparent marked-off
    > square). It was the invention of Sir Charles Douglas, an army man, who
    > got a
    > British patent for it (3461 of 1811). I haven't discovered if there's a
    > way
    > to access UK patents without visiting the British Library, so if anyone
    > knows how to do that, that would be of interest.
    Actually, I believe Sir Howard Douglas, son of Admiral Charles Douglas was
    the inventor.  The oldest hall at the Royal Military College is named
    after him.
    At any rate, another interesting reference that *may* be closer to your
    independent invention is to be found by a Google Book search for
    "Reflecting Sector" in Philosophical Magazine, of around 1822, pages 301
    to about 310.  Unfortunately, there are no drawings to correspond with the
    description of the device by Professor Amici of Modena; but I have seen
    something that might match in other image searches for "reflecting sector"
    and "Amici".
    The device operates over a range of 180 degrees, uses triangular and
    rectangular prisms; and does sound interesting.
    Unfortunately, I had to use Internet Explorer to get the pages below;
    Opera didn't work.
    Richard . . .
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