The ancient Egyptians recorded their dates according to the regnal year of the reigning king. So when a new king entered the throne, they started counting ten years again from one.
The ancient Egyptians were the first to introduce the concept of twenty-four hours in a day. Night and day were both divided into twelve hours. Prior to 127 BC, the length of the hours varied depending on the season. Early time keeping devices and calendars depended on the movement of the Sun and Moon.
Around 3500 BC, one of the first timekeeping devices, the gnomon is developed in ancient Egypt.
A gnomon is composed of a vertical stick that casts a shadow on the ground or a stone base when left in the sunlight. Scholars estimate the time by looking at the position of the shadow.
The gnomon is a precursor to the sundial. A sundial is a device for measuring the hour of a day. In general, a sundial consists of the gnomon that is also called the style and the surface engraved with the timescale for indicating the time of a day.
The shadow of the gnomon is projected on the surface. When the sun moves in the sky, the corresponding gnomon’s shadow moves in the surface. According to the position of the gnomon’s shadow, the hour of a day is identified.
And by 1500 BC, in Egypt, the sticks were replaced with monumental decorated spires called obelisks, which were built in city centers.
Around 3500 BC: ancient Egyptian develop timekeeping device
