Sundials

Sundials were the earliest type of timekeeping device.

The sundial indicated the time of day by the position of the shadow of some object exposed to the sun’s rays. As the day progresses, the sun moves across the sky, causing the shadow of the object to move and indicating the passage of time.

The first device for indicating time of day was probably the gnomon, dating from about 3500 bce. The Gnomom consisted of a vertical stick or pillar, and the length of the shadow it cast gave an indication of the time of day. By the 8th century more-precise devices were in use.

The earliest known sundial still preserved is an Egyptian shadow clock of green schist dating at least from this period. Clocks of this kind were still in use in modern times in parts of Egypt.

With the advent of mechanical clocks in the early 14th century, sundials with equal hours gradually came into general use in Europe, and until the 19th century sundials were still used to reset mechanical clocks.

Britannica, The Editors of Encyclopaedia. "sundial". Encyclopedia Britannica, 12 Dec. 2023, https://www.britannica.com/technology/sundial. Accessed 6 February 2024.