Roman Timekeeping
Day 312 / 365
As a kid, I used to think that we had 12 hours of the day and 12 hours of the night. As an adult, however, I now perceive night as just being a 6-hour interval between two workdays, and I am sure a lot of people will agree with me.
While all that is just in my head, the length of days and night does actually vary from season to season and from place to place. For instance, in Iceland right now sunrise to sunset is just about 7 hours. In ancient Rome, people still tried to keep an equal number of hours for day and night. Their clock was divided into 12 hours of light and 12 hours of darkness. This meant that the length of the hours changed with the seasons. Day time was shorter in winters, so each ‘day-hour’ was only about 45 minutes. Similarly in the summers, each ‘day-hour’ could go up to 75 minutes.
You would think that why did they think of such a complex system, and how did they make clocks that could measure in it?
If you think of sundials, it all becomes pretty clear. In a sundial, time is measured by the movement of the shadow of something kept under the sun. Suppose during the course of the day, the shadow moves from point A to point B. When you have shorter days, the shadow would move quickly, thus giving you shorter hours.