Ultra Scarce 1940s Glenn Colorule for Testing Color Vision oval dish clinical looking dark green box

clinical looking dark green box with silvery white print and one initial--"M" in this case

and those big pencil-drawn spots drawn on the larger horse

allowing for control of the arms

Tiny text on all of them reads "Registered" and on a few is printed them reads Copyright 1896 F

Some wear to the lacquer around the edges on the sides

Ultra Scarce 1940s Glenn Colorule for Testing Color Vision oval dish clinical looking dark green boxI have found a bunch of academic papers and studies discussing the use of the Glenn Colorule, but can't find even a picture of another out there anywhere. There are records of in a few academic libraries, so I know it was produced by s explained on the box text, it was made to be used to test the color vision of observers, to test the quality of light sources, and or to demonstrate disagreement caused by "pseudo," or false, color matches. There's a