How Do You Know What Time It Is? (Albert Whitman Prairie Books)

Time is a mystery. And even though we can't see it or touch it, we can measure it--with clocks. But a long time ago, there were no clocks. Back then, people measured time by the sun. Egyptians were the first to keep track of time, with a shadow stick clock, and they were the first to divide time into hours.

While clocks kept track of hours, the moon helped keep track of months. The first calendar was a lunar one, but it was soon discovered that it was not exact. The calendar was then based on the sun, and it was Julius Caesar who added a day to February every fourth year to make the calendar even more accurate. Robert E. Wells covers the history of measuring time with funny and interesting examples and illustrations.