The Theory and Practice of Aerial Sighting (1919) RFC and wear to the silk

and wear to the silk lining

with general signs of use

but this type of round wooden compass was only made in limited numbers and is much more uncommon

25mm depth

including the O

The Theory and Practice of Aerial Sighting (1919) RFC and wear to the silkTHE THEORY AND PRACTICE OF AERIAL SIGHTING F. S. Publication 118 AIR MINISTRY, London, 1919 A mans flying ability may be perfect; he may be able to control the machine like no one else on earth, but if he goes into a fight and risks his life to get into the right position for a good shot, and, upon arriving there, cannot hit the mark he is useless Major W. A. Bishop V. C., D. S. O., M. C. The Theory and Practice of Aerial Sighting is a very rare RAF