PB2Y/PBM Seaplane Airframe Pocket Reference US Navy 1942/3 C-45 and possibly military aircraft of

and possibly military aircraft of that era

This indicator has a serial number prefix "AC-40"

formation flight

however only the screws are present

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

PB2Y/PBM Seaplane Airframe Pocket Reference US Navy 1942/3 C-45 and possibly military aircraft ofThis 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.