Kodak model 1 color densitometer vintage photography equipment

Vintage Kodak model 1 Color Densitometer from the estate of a World War II US Navy photographer. We don't know much about this, but have been told that these were made during the 1940s and 1950s. It is calibrated from 0.0 up to 3.0 in 0.1 step increments. We plugged this and a small lamp inside lights when we flip the switch.

There are some cracks to the one corner of the black bakelite housing and it has been taped with a piece of black friction tape (the predecessor to electrical tape.