††††The first clocks were sundials, used by Egyptians around 1500 BC. They also developed the water clock shortly after this. Pendulum clocks appeared in the 17th century, a century after Galileo had toyed with the idea. The 17th century also saw the introduction of the minute hand to clock faces. The electric clock was made possible by the discovery early in the 19th century of the magnetic effects of electric currents. The modern quartz crystal clock makes use of this principle and is accurate to about one-thousandth of a second a day. More accurate still is the atomic clock.
