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http://naca.larc.nasa.gov/reports/1925/naca-report-198/

contains a PDF file (3.8 MB) of a document written in 1925 entitled

   "Astronomical methods in aerial navigation"

that can be downloaded.  It also can be read online, but if you
download it you can zoom in and read things better using Adobe Acrobat
rather than your web browser.

This publication describes several sextants by name, none of which I
have heard of before.  The sextants described include:

Baker aircraft sextant
Marcuse sextant
Harmann sextant
Lindt sextant
Byrd sextant
Willson sextant
Schwarzschild sextant
R.A.E. sextant
Fischer sextant
Fischer pendulum horizon
Fleuriais sextant
Derrien sextant

and so forth.  For those interested in early aircraft engineering, this
website is a gem with many old NACA documents online.  NACA was the
National Advisory Committee for Aeronautics, the precursor to NASA, and
it was active from 1917 to 1958.

Here is the summary for the document:

The astronomical method of determining position is universally used in
marine navigation and may also be of service in aerial navigation. The
practical application of the method, however, must be modified and
adapted to conform to the requirements of aviation. Much of this work
of adaptation has already been accomplished, but being scattered
through various technical journals in a number of languages, is not
readily available. This report is for the purpose of collecting under
one cover such previous work as appears to be of value to the aerial
navigator, comparing instruments and methods, indicating the best
practice, and suggesting future developments. The various methods of
determining position and their application and value are outlined, and
a brief resume of the theory of the astronomical method is given.
Observation instruments are described in detail. A complete discussion
of the reduction of observations follows, including a rapid method of
finding position from the altitudes of two stars. Maps and map cases
are briefly considered. A bibliography of the subject is appended.

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Fascinating!

Dan

   

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