Morphology and evolution of the gnomon

The sententious fragment: In the tropics — that is, in the latitudes between the Tropic of Cancer and the Tropic of Capricorn — there are two moments in the course of the year when the sun passes directly overhead and an object won’t cast a shadow longer or wider than itself. The first of these occurs when the sun is on its way north to the Tropic of Cancer, which it will reach on the summer solstice; the second occurs when the sun is on its way back south to the Tropic of Capricorn, which it will reach on the winter solstice. For 2021, the first moment in tropical Honolulu was on May 26 at about 12:29.

The whole:

 

 

Where time sleeps with shadow

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Lester Jones, August 24, 1940, “FIRST FLOOR, STAIRHALL – Shaker Centre Family Dwelling House (Third), North side of Village Road, North of Route 68 & State Route 33, Shakertown, Mercer County, KY.” Historic American Buildings Survey, Library of Congress, https://www.loc.gov/pictures/item/ky0033.color.572148c/. Post-processed for color and detail. Additional data about this series of photographs are at https://www.loc.gov/pictures/item/ky0033.photos.071803p/.