What did ancient egyptians use shadows for?

Answer 1

erasthenes who lived in Alexandria Egypt but was greek used shadows to measure the circumference of the earth first noting that the sun at noon cast no shadow on statutes then travelling 500 miles away to syrene (Libya) and noting the shadows cast a shadow of 7 degrees at noon he then calculated that there was 360 degrees in a circle there for calculated that the earths cicumfrence must be 25 500 miles this was not entirely accurate but a very close