This Ancient Egyptian “shadow clock” dates to the Ptolemaic Period (330-306 BCE), but is representative of the earliest known timepieces. The earliest extant dates to about 1500 BCE, but this fragment is much more interesting to look at. Check out the parallel and oblique lines engraved on the sloping face: one would have placed a block perpendicular to the slope side, and, with an absolutely accurate east-west orientation, and an absolutely level floor, the shadows cast could mark off the time. You would have to turn the shadow clock around between morning and afternoon: it was a portable, if finicky, timepiece!
The earliest mention of a sundial in literature comes from the Hebrew Bible. In both Isaiah (ca. 750-550 BCE) 38:4-8 and 2 Kings (ca. 550, with the author using Isaiah) 20:9-11, God moves the shadow of a sundial backwards ten degrees as a miraculous sign that he will cure Hezekiah of an illness and allow him to live 15 years longer. The Egyptians and Babylonians who had excelled at timekeeping technology, spread the use of the sundial to neighboring people.
Source(s): The Metropolitan Museum of Art, accession number 12.181.307. _Ancient Jew Review_, Dec 18, 2019, “Turning clockwise: Jews and timekeeping from Antiquity to Modernity,” David Zvi Kalman.
