PB2Y/PBM Seaplane Airframe Pocket Reference US Navy 1942/3 C-45 It consists of a master

It consists of a master unit containing both the gyro and magnetic elements normally stowed in a part of the aircraft away from large masses of magnetic material which would distort the Earth’s magnetic field

This is a WWI or Post WWI-vintage aircraft or laboratory tachometer "Victometer" made by the Jos W Jones Co

and training aircraft

We have not independently verified the information on the tag

and possibly military aircraft of that era

PB2Y/PBM Seaplane Airframe Pocket Reference US Navy 1942/3 C-45 It consists of a masterThis is a Pocket Reference Handbook containing 8 diagrams of the airframe stations of the US Navy's Patrol Bombers PB2Y Coronado and the PBM Mariner. This ~6 inch x ~4. 5 inch pocket reference was likely used by maintenance technicians at US Navy seaplane bases operating these two aircraft. The diagrams, showing these aircrafts' hull stations and wing stations, are dated 1942 and 1943. It is in reasonable condition given its age.