I have a compass which was obviously from a first world war aircraft -Scratched on the rear surface by a former owner are the following "DH7 bombed Cologne Aug 18 " no year -the front bezel has "Air Compass Type 5/17" -it was at one time liquid filled-I would be interested to know if this was indeed from that aircraft and if it was on a bombing run over Cologne on that date and if so in what year--- Greg