Why an hour has 60 minutes (and the failed attempt to make it 100)

Sixty Minutes in an Hour: The Ancient Puzzle Behind Our Time. Imagine a world where each hour lasts a hundred minutes and the day is made up of just ten hours. For a brief moment in the late 18th century, during the fervor of the French Revolution, this nearly became reality. Determined to rationalize every aspect of life, revolutionaries introduced a decimal system for time: ten-hour days, with each hour divided into one hundred minutes. Yet, the experiment quickly collapsed. Converting the clocks proved to be a logistical nightmare, the new calendar isolated France from its neighbors, and most people simply ignored the new hours, clinging to the familiar rhythms of life. But why do we divide our days into 24 hours, with each hour containing 60 minutes and each minute 60 seconds? To unravel this, we must journey back five millennia to ancient Mesopotamia, where the Sumerians pioneered one of the world's first written numerical systems. Unlike our modern decimal system, the Sumerians counted by sixties—a base-60, or sexagesimal, system. Its beauty lies in its divisibility: 60 can be divided evenly by so many numbers, making calculations for trade, land division, and even inheritance considerably easier. The Sumerians’ clever mathematics laid the groundwork, but it was the Egyptians who first divided the day into hours. Their choice of 12 hours for the night and, eventually, 12 for the day likely stemmed from religious or astronomical traditions, though the reason remains a mystery. It wasn't until the Babylonians, inheriting the Sumerian love for sixty, began to subdivide hours for astronomical purposes—creating the minute and the second as we know them. In the melting pot of the Hellenistic world, Greek scholars absorbed these Babylonian conventions. The system survived through centuries, even though it remained a distant concept for daily life, relevant mainly to astronomers and priests. Only with the advent of precise mechanical clocks in recent centuries did minutes and seconds become a part of everyone's day. The French quest for decimal time failed spectacularly, lasting just 17 months. The sexagesimal system, by contrast, has outlasted empires and revolutions, woven into the very fabric of how we experience and measure our lives. Every tick of the clock today carries with it a legacy of ancient civilizations, a testament to the enduring power of practical mathematics and the inertia of human habit. It turns out that changing the way we tell time is far harder than changing almost anything else.