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Early Egyptians told time using the obelisk. An obelisk was a shadow clock and was a vertical structure with four sides. It was placed in the sun and the shadow cast showed the position of the sun throughout the day.
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Babylonians began using a sundial. A sundial is a flat circle with a 12 hour clock face. A gnomon stood vertically in the middle of the sundial and cast a shadow on the correct hour as the sun's position changed.
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Used in Europe by the 11th century, this was one of the first "time pieces" or "time keepers" that could be used without the light of the sun.
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The first mechanical clocks appeared in Europe. These clocks used weights and balances to keep time and were quite large in order to hold the weights.
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The first watches were developed in Italy. These small, portable "time pieces" were worn on a belt or placed in someones pocket.
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European scientists discovered that a pendulum could be added to a mechanical clock to increase a clocks accuracy to minutes and even seconds.
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Standard time was used for greater accuracy. The earth was divided into 24 different time zones. The time zones reflect how long it takes each part of the earth to travel through the prime meridian, which is located in Greenwich, England.
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This highly accurate system for telling time (which allows for slights variations in the rotation of the earth) is accepted around the world as the official measure of time for the planet.
