Timepieces

From shadow on sand to atomic clocks — humanity's chase of ever-more-precise time.

28 posts· 3500 BCE – 2026

• The nucleus as clock: thorium-229 and the end of atomic timekeeping's monopoly 2026
• What time is it on the Moon 2026
• One lutetium ion, nineteen decimal places 2026
• Xi'an joins the timekeepers 2026
• The aluminum ion clock, or how NIST gave time nineteen decimal places 2025
• Apple Watch, 2015: the wristwatch that became a medical device 2015
• GPS time: the satellite clock that runs wrong on purpose 1995
• Swatch, 1983: the paper-towel sketch that saved Swiss watchmaking 1983
• Seiko Astron: the wristwatch that rewrote time 1969
• Essen's Flying Bedstead and the death of the astronomical second 1955
• The quartz clock and the wobbling Earth 1927
• The wristwatch goes to war 1917
• The Waltham watch factory, or how time stopped being a luxury 1854
• Breguet's wristwatch, or the timepiece that arrived fifty years too soon 1810
• John Harrison's H4 and the Longitude Prize 1759
• Huygens's pendulum clock: fifteen minutes become fifteen seconds 1656
• Galileo's pendulum, or the clock he never lived to build 1583
• Peter Henlein's pomander, or the clock that fit in a hand 1510
• Henlein's pocket clock, or the day time left the tower 1510
• Peter Henlein's pocket watch, or how time learned to travel 1510
• Peter Henlein's watch, or how a fugitive locksmith put time in your pocket 1510
• The Salisbury clock, or the machine that forgot to have a face 1386
• The mechanical escapement, or when clocks learned to tick 1283
• Su Song's clock tower, or the machine that told the whole sky 1088
• The incense clock, or how China measured the night in smoke 520 CE
• Ctesibius's clepsydra, or the water clock that fixed itself 250 BCE
• The Egyptian clepsydra, or how priests told time without the sun 1500 BCE
• The shadow clock, or how Egypt turned sunlight into hours 3500 BCE