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Sundials are some of the earliest instruments and measure time. Sundials date to ancient Egypt and were still widely used during the nineteenth century to check the accuracy of clocks and watches. Because the sun appears to move at different rates depending on location, horizontally fixed sundials are calibrated for specific latitudes. This equinoctial inclining sundial includes a compass for alignment and a hinged dial face that adjusts to various locations listed on the back. “Curiosity & Discovery: Antique Scientific Instruments” is on display, post-security in Harvey Milk Terminal 1 and online at: https://bit.ly/AntiqueScientificInstruments. All objects are courtesy of Mark McElyea.
This image was posted on November 02, 2021.