NavList:

I was interested in the photographs of the Hughes Aircraft Sextant Lot 689 often described as a Flying Boat Sextant, although it would have been useful in any maritime aircraft flying in clear conditions with an accurate knowledge of sea level pressure.  Its number 28,125 and certificate 16^th Dec 1941 is not much younger than my own Mate’s Three Circle Sextant 25,410 whose certificate is dated 16^th Jan 1941, and it is signed by the same D A Perkins.  The interesting thing is that both arcs are claimed to require no correction although the units are different.  My Mate’s six inch radius sextant reads to ten seconds of arc and Mr Perkins claims the arc requires zero seconds corrections.  For the aircraft sextant, which is only three and a half inch radius and has no Verniers, Mr Perkins claims that it reads to one minute of arc and requires zero minutes corrections.  Therefore, it’s interesting to speculate what Mr Perkins is actually claiming on the certificate.  I presume it means “For the purpose we expect you to use this sextant and the accuracy you can expect due to the conditions your working under, you don’t need to worry about the cutting and marking accuracy of the arc.”  Comments please.  Dave P