The History of Timekeeping

For most of human history, people measured the passing of time by the natural world around them. The rising and setting of the sun divided day from night, the changing face of the moon marked off the months, and the slow turning of the seasons guided the planting and harvesting of crops. Such timekeeping was perfectly good enough for societies built mainly around farming, where the exact hour of the day rarely mattered very much. Early devices such as sundials and water clocks could divide the day a little further, but they were not very precise and often disagreed with one another.

The invention of the mechanical clock in medieval Europe gradually changed all of this. At first found mainly on the towers of churches and town halls, clocks slowly began to impose a new and far more regular rhythm on daily life. Time could now be divided into equal hours that were exactly the same length in summer and in winter, and bells called people to work, to prayer, and to meals at fixed and shared moments. As clocks became smaller and cheaper over the centuries, more and more people came to organize their entire lives around them, a habit that would surely have astonished their distant ancestors.

Even then, however, each town typically kept its own local time, based simply on the position of the sun overhead. This caused little real trouble until the arrival of the railway. Once trains could carry passengers between distant cities in a matter of hours, the small differences in local time suddenly became a serious problem for making timetables, and the resulting confusion could even lead to accidents. To solve this, countries introduced standard time zones, in which large areas all agreed to share a single official time. The clock, once a rare luxury, had become a strict master that everyone, everywhere, was now expected to obey.