Planisphere of Air Navigations Stars

This ingenious device is attributed to Flt. Lt. Francis Chichester RAFVR who later gained internation fame sailing around the world and subsequently receiving a Knighthood. He was clearly qualified in his subject having won the Johnston Memorial Trophy for Air Navigation in 1931. The instrument was designed to help air cadets (and others)in learning to identify the stars required for navigation. The book contains two rotating planispheres showing the various constellations in the Northern and Southern Hemispheres. It is named to AC.I Drew. J. E. and numbered 12989429. It appears to be in good working order and while we do not know the date of publication, clearly after 1931 and the retail price was a hefty 2 shillings and 6 pence!