Time Keeping Devices

Improving on the sundial the Egyptians used a merkhet, the oldest known astronomical tool. The exact design for the merkhet consists of a horizontal bar, carved from wood or bone. A plumb-line hangs from a transverse hole at one raised end of the bar, this being attached to a controlling wooden handle. To operate properly, two merkhets are required, one aligned with Polaris (North Pole) star. By observing the transits of certain stars as they crossed the meridian and came into alignment with the two merkhets, time could be estimated very accurately.
The Egyptians also developed water clocks, most likely used in the Precinct of Amun-Re. Outside of Egypt, the Ancient Greeks called them clepsydrae. These outflow water clocks were believed to have been introduced from Mesopotamia, maybe even as early as 2000 BC to the Shang Dynasty of Ancient China.
Around 3000 BC Mesopotamia began to standardize the hour. And following the Egyptians 24 hour day, ancient Sumerians, also based their number system on 12. Approximately a 12 hour day and a 12 hour night was standardized so they would no longer exactly correspond to the Sun, but remain consistent throughout the year.

I found some interesting pictures and attached the URL to some of the images at the right.

Origins of Time

Since the beginning of the human race man has not only been concerned about time, but being accurate in keeping time. This leads to an interesting question. Where and when did time-keeping start? Examination of several cultures and world history raises more questions. Did time-keeping begin with the Ancient Egyptians, the Ancient Greeks, The Romans, or maybe the Ancient Chinese?

In this article we will examine Egyptian history: Conventional Egyptian chronology represents the scholarly consensus of ancient Egypt's Protodynastic Period beginning about 3200 BC. Early Egyptians built obelisks (tall 4-sided tapered monuments) placing them in specific locations to cast long shadows. Around 1500 BC, they developed a more accurate "shadow clock" or sundial. This was only good for about half a day and then had to be turned 180 degrees. An instrument very much like a carpenters T-square was developed as a third shadow clock around 1500 BC. The T being oriented eastward until noon, and then rotated to cast a shadow in the opposite direction. This enabled the shadow of the crossbar on a non-linear rule to give adequate time. Overcast days left a lot to be desired for those needing to be executed at 12 noon.

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