We were recently contacted by Dan Clouse, Society Member 42181, who had read an article about the cyanometer, an instrument created purely to measure the blueness of the sky.

It was created in the 18th century by a Swiss scientist, Horace-Bénédict de Saussure who climbed to the summit of Mont Blanc to measure the depth of blueness of the sky as mountaineers had reported that the sky was a deeper blue the higher they ascended.

You can see the full article on the Atlas Obscura website.