Ultra Scarce 1940s Glenn Colorule for Testing Color Vision folk art church I might guess 1940s-50s

I might guess 1940s-50s

and then a turned and threaded handle

) I just love their imperfectly cut

but can provide one

with some range in age of jacks

Ultra Scarce 1940s Glenn Colorule for Testing Color Vision folk art church I might guess 1940s-50sI 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