Innovation No. 19 of 77 in the book
The Clock
Water clocks measured time through the night
- When
- c. 1350 BCE
- Dynasty
- 18th Dynasty
- Era
- New Kingdom
The first machine that kept time on its own was a bucket of water. Egypt’s oldest surviving water clock dates to around 1350 BCE, from the reign of Amenhotep III.
Water drains at a steady rate through a small hole; falling markings inside the vessel show the hours passing. Unlike a sundial, it worked at night and indoors.
Priests used them to time temple rituals through the dark, when the stars were hidden by cloud.
The whole idea of a device that measures time by itself — clock, watch, timer — begins here.
The oldest surviving water clock was found at Karnak in 1904 and dates to the reign of Amenhotep III, around 1350 BCE; the decorated alabaster vessel, with a small copper outlet at its base, is in the Egyptian Museum in Cairo. An inscription in the tomb of the court astronomer Amenemhet, around 1500 BCE, records that he designed one for Amenhotep I and calculated its proportions to match the changing length of the night hours.
Frequently Asked Questions
Why is the vessel cone-shaped?
To beat the physics. Draining water slows as the level drops and pressure falls. Making the vessel wide at the top and narrow at the base meant each falling hour had less volume to empty, which cancelled the slowdown and kept the hour marks even.
How were the hours marked inside?
As columns of dots on the interior wall — twelve of them, one for each month, because the length of a night hour changed through the year.