JULY 20, 2024 GRACE EBERT

All photos by Franziska Strauss, © Macarena Ruiz-Tagle,

Users hold the work up to the sky, mark the corresponding hue, and share a thought or two before dropping it in the mail.

While exploring the Alpine region around Mont Blanc in 1789, the Swiss physicist and mountain climber Horace-Bénédict de Saussure (1740-1799) conceived of a tool to measure the blueness of the sky. He developed a round instrument dubbed a cyanometer with 53 shades dyed from Prussian blue he could hold up and compare to the atmosphere above. Saussure correctly predicted that the color correlated with the amount of water present, handy information for someone intending to scale a mountain.

Artist Macarena Ruiz-Tagle created a new version of the 18th-century tool for the 13th Annual Architecture Venice Biennale. Whereas the original cyanometer was geared toward personal use, Ruiz-Tagle’s design is outfitted as a postcard. Users hold the work up to the sky, mark the corresponding hue, and share a thought or two before dropping it in the mail. […]

More: Share the Sky with Someone Far Away with These Cyanometer and Sunset Postcards — Colossal