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    Re: Rust's diagram for computing azimuth
    From: Gary LaPook
    Date: 2007 Oct 11, 21:59 -0700

    Gary LaPook writes:
    The Burdwood table looks just like H.O. 214 minus the altitudes. (Or
    H.O. 249 at a lower precision.) I am wondering how usefull Burdwood
    would be at this late date since these other tables are now available.
    Rust's diagram has the advantage of needing only two pages and can be
    used with any of the trig table methods of compurting altitudes.
    On Oct 9, 6:22 pm, John Cole  wrote:
    > Here�s a page from Burdwood�s Tables. The latitude limit is 64 degs in the
    > second edition. Commander John Burdwood RN was was in the Admiralty
    > Hydrographic Department.  The second edition 1940 was revised by Percy Davis
    > FRAS of HM Nautical Almanac Office.
    > From: Peter Fogg 
    > Reply-To: 
    > Date: Wed, 10 Oct 2007 09:54:34 +1000
    > To: 
    > Subject: [NavList 3396] Re: Rust's diagram for computing azimuth
    > Can you let us know some more information about these Burdwood's Tables,
    > John?
    > On 10/10/07, John Cole  wrote:
    > > In an earlier time Burdwood's Time Azimuth Tables were used
    > > extensively to correct the compass and for other purposes, indeed
    > > according to the preface of my 1940 second revised edition "for fifty
    > > years Burdwood's Tables have been known and used by every seaman". The
    > > full title is "Sun's True Bearing or Azimuth Tables." Those who
    > > learned navigational astronomy from Smart's venerable "Spherical
    > > Astronomy" or his wartime "Handbook of Sea Navigation" will be
    > > familiar with them.
    > > On Oct 8, 1:42 pm, Gary LaPook < glap...@pacbell.net> wrote:
    > >> > Gary LaPook writes:
    > >> > Attached is Rust's diagram for computing the azimuth of the sight which
    > >> > was included in Weems "Line Of Position Book," 1927. It was developed
    > >> > using the sine formula. You enter on the left with LHA and go to the
    > >> > right to the declination then straight up to the altitude then to the
    > >> > right to the azimuth. Also included is a table used to determine in
    > >> > which quadrant the azimuth falls when the body is close to east or west.
    > >> > This diagram can be used with any set of tables, H.O. 208, H.O. 211,
    > >> > etc., and the extra steps used in those tables to compute the azimuth
    > >> > can be disregarded.
    > >> > The shape of these curves show  the potential loss of accuracy using the
    > >> > sine formula as the azimuth approaches 90� as the altitude curves become
    > >> > almost vertical and only slight changes in altitude results in large
    > >> > azimuth changes.
    > >> > --
    > >> >  Rust diagram.pdf
    > >> > 206KDownload
    >  Burdwood's Tables.pdf
    > 4628KDownload
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