|"The interest in keeping a record of time has progressed over thousands of years with timepieces ranging from ancient sundials to modern atomic clocks. The earliest examples of measuring time were based on observing the position of the sun, moon, and constellations. This practice was followed by man-made devices, traced to early civilizations, using the shadow of the sun to determine the time of day as well as those that could function on cloudy days or at night. While some of this information has been lost to the ages, inventions of some timekeeping devices have been recorded dating back to Egyptians of the 16th century B.C.|
One form of keeping time was a portable shadow clock or sundial developed by the Egyptians around 1500 B.C. This was a long stem with an elevated crossbar at one end that would cast a shadow that lengthened or shortened, depending on the location of the sun. In the mornings, the stem was oriented in an east-west direction and the crossbar was on the east end. The long stem had five marks of variable spacing. Since the day was divided into 10 parts with two additional parts representing morning and evening twilight, the device was turned around to measure the afternoon shadows."