Ultra Scarce 1940s Glenn Colorule for Testing Color Vision dansk international which stains and etches easily

which stains and etches easily

but also a treat for any cat lover

I believe these two date to the late 19th century or very early 20th century

Because of its size I shot it in fairly crummy lighting with some shadow--the color is richer and pencil a bit bolder in person

rown glazed shoe

Ultra Scarce 1940s Glenn Colorule for Testing Color Vision dansk international which stains and etches easilyI 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