This is an Oil Temperature gauge type A-24. The glass on this instrument has been tarnished on the inside from some form of adhesive, most likely used to keep the glass from rattling, perhaps when an O-Ring could not be found. We will be cleaning it shortly.
The serial number is 42-79275. This matches that of the Waco CG-4A-WO. This seems possible, however I could not confirm that this aircraft used this type of instrument. The prototypes of the aircraft used either one or two engines, going back and forth between models. Every prototype had engines mounted below the wings, however the final production variant has no engines in, above, or below the wings. It was designated a glider, meaning that the final variants had no engines at all. This instrument was likely produced using serial numbers matching that of this aircraft, but was instead used as a replacement part for other aircraft.