Example image of eyePlorer eyePlorer map for 'History of timekeeping devices': Time Numeral system Sexagesimal Sumer Systems of measurement Ancient Egypt Obelisk Ancient Greece Precinct of Amun-Re Water clock Mesopotamia Shang Dynasty Candle clock Hourglass Clock Gnomon Escapement Gear Inventions in medieval Islam Maintaining power Pendulum clock Pocket watch Spring (device) Verge escapement Atomic clock Crystal oscillator Watch Coordinated Universal Time International Atomic Time Astronomical object Moon Sun Egypt Mesoamerica Western world Calendar Hunter-gatherer Last glacial period Lunar phase Equinox Prehistoric Europe Solstice Stone circle Stonehenge Megalith Recorded history Sundial Egyptian language Schist Daytime (astronomy)