Good question. Counting minutes obviously came first as devices likes hourglass and water clocks are old (2000 BCE). Regarding their precision, I got interest

Good question. Counting minutes obviously came first as devices likes hourglass and water clocks are old (2000 BCE). Regarding their precision, I got interested and per this paper [1] and the wikipedia page about traditional Chinese timekeeping [2], water clocks from two millennia ago might have around 15min precision. For second level precision, it seems modern mechanical clocks were required, and they only precede the discovery of caesium by a few centuries. [1] https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S025292110010586X https://www.cambridge.org/core/services/aop-cambridge-core/c... [2] https://en.m.wikipedia.org/wiki/Traditional_Chinese_timekeeping https://en.m.wikipedia.org/wiki/Traditional_Chinese_timekeep...