These were the first Egyptian sundials. Ancient Egyptians also made the first water clocks. These were buckets filled with water that had holes in the bottom of them. As the water level decreased, the markings on the inside would show what time it was. The earliest of these was found in king Amenhotep I's tomb. Another kind of water clock was a bowl with a hole in the bottom. When it was placed in a bigger container of water the bowl would fill and sink in a certain amount of time. These water clocks are still used in North Africa. A more common type of clock was the hour glass. It was more versatile because it could be use din winter, unlike the water clocks. An hour glass is "two bubbles of glass with a narrow middle". Sand is measured and sealed inside and turned over and over again. Hour glass were used to measure short periods of time, such as cooking, speeches, or sermons. How ever they were often inconvenient. Hour glasses had to be on a flat surface to work, and sometimes coarse grains would wear away and make the opening bigger.
3) In 1656, a Dutch scientist named Christian Huygens made the first pendulum clock, using a method of "natural oscillation". His margin of error was less than one minute per day. Later, his design was improved to have a margin of error of only 10 seconds per day. In 1657, Huygen developed the "balance wheel and spring assembly". Tis had a margin of error of only 10 minutes per day. George Graham in 1721 invented a pendulum where the degree of accuracy to one second per day, because of temperature changes which changed the pendulum's length. Later, it was improved to "a hundredth-of-a-seocnd" when it was then used as the standard in astronomy observatories. Quartz clocks were later developed. They were base don the piezoelectric property or quartz. When squeezed, quartz emits an electrical field, and when an electrical field is placed around it, it changes its shape.