Sundial / shadow clock
Reloj de sol y gnomon
- Date
- c. 1500 BCE · confidence medium
- Place
- Valley of the Kings, Thebes, Egypt
- Credited to
- New Kingdom Egyptians
- Field
- Knowledge & symbols
⚠️ Disputed: the sources disagree.
What it is
An L-shaped bar or plate with a gnomon whose shadow marks the hours of the day on a graduated scale. The example from the Valley of the Kings (c. 1500 BCE) and obelisks are the earliest documented sundials.
Merkhets (star-alignment instruments, c. 1500 BCE) complemented the sundial at night; Egyptian hours were unequal, varying by season.
What it led to
- Division of the day into hours and organisation of work into shifts on royal building projects
- The hour as a unit of time, later inherited by Greece and Rome
- A link between astronomy and civil life
Built on
Made possible
- Water clock (clepsydra)c. 1500 BCE
- Merkhet (Egyptian stellar sighting instrument)c. 600 BCE
- Tower of the Winds of Athensc. 50 BCE
- Yi Xing's meridian arc survey724-725
- Astronomical quadrantc. 850
- Jai Singh II's monumental astronomical instruments (Jantar Mantar)1728-1734
- Greek sundial
- Mechanical clock (distant ancestor)