In 1793 the French Revolution decimalised the day: ten hours, each of a hundred minutes, each of a hundred seconds, and clockmakers built dials to match. The new hours were made compulsory in September 1794 and suspended in April 1795, while the metre, born of the same reform, went on to most of the world. So the clock on every wall still counts in sixties, a habit handed down through Greek astronomers from Babylon.

One reason it held may be that sixty is generous. It divides evenly into halves, thirds, quarters, fifths, sixths, tenths and twelfths; a hundred cannot even manage thirds. “Twenty past” is a third of an hour said without a fraction. We don’t so much measure time as share it out between people, and the old number was better at sharing.