People are often curious about the purpose of the bubble sextant and wonder how to use it.
The basic idea is that from an aircraft, the horizon no longer serves as a
reference for horizontal
as it does at sea level. So a bubble level was used instead. Some models also had an interesting
clockwork device to help the operator average many readings. More information can be found
in the entry on "sextant, aircraft" by Peter Ifland in Instruments of Science, R.Bud and D.J.Warner,
(Garland, New York 1998) and in the book, From Sails to Satellites , by J.E.D.Williams, ( Oxford Uni. Press, Oxford,1992).
A small instruction manual is available in as a pdf courtesy of Tony Meacock.
Bubble Sextant Manual (pdf)
Scans of the small instruction manual found with a model IXA bubble sextant ("Ref. 6B/218") can be downloaded by clicking below. In order to avoid degrading the already low quality further, the files will overfill a normal browser page and it will probably be necessary to save the files and view them with a graphics editing program (eg Microsoft Photo Editor).
Pages 1-4 ( 103 kB)
Pages 5- 8 ( 117 kB)
Pages 9-12 ( 116 kB)
Pages 13-16( 104 kB)