About 3500 BC, people still use the Sun to know. It is very simple, round plates with a stick in the middle. Sticks in the Sun, he serves as an hour. Looking at the drop shadow sticks in the range of plates, who knows, at the time. In 1300 BC, Ctesibus from Alexsandria to watch by using the tools of sand.
Sand is easily available in almost all places and different from water, sand does not freeze in the cold. Glass, sand sculptors time about 1,200 years ago began to be used, form a very little changed. To maintain the perfect stay dry sand, sand in place in place of the meeting stringent water glass, which narrowed in the middle. Sand trickle from a small hole in the bowl or elsewhere can clearly be used to measure time that way with regular water droplets. Because it is not surprising, hour-glass has been used for centuries. Very old hourglass in the lower house at Westminster which measures the time of two minutes to ring a bell to summon the members of the assembly to hold elections.
Place the sand was installed in the rack, which can be revoked is back. Or place, mix sand and turning his location, so the sand flows continuously.
