Nowadays, we are able to use many different types of clocks – all guaranteed to keep time to a very high degree of accuracy. These clocks run by mechanical, electrical, digital or even atomic power. The earliest is the mechanical clock – but even that was invented only a few hundred years ago. Then how did people of long ago measure time? What were the first clocks invented by Man?
Shepherds in ancient times were among the first to assess the time of the day by watching the shadows shorten and lengthen as the sun passed overhead. This became the basis of the first timepiece invented by Man: the sun-dial. Sticks or poles were stuck into the ground, and the angle of the shadow showed what time it was. It is believed that the Chinese used sun-dials as long ago as 2670 B.C. and the ancient Egyptians and Assyro-Babylonians had similar instruments. But the credit for the invention, in 500 B.C., of a really scientific solar timepiece goes to the Greek, Anaximander. Sun-dials had appeared in Rome by 291 B.C.: the iron hand of one famous sun-dial was attached almost perpendicularly to a wall, on which radiating lines marked the hours of the day as the shadows fell upon them. However, sun-dials had one great drawback: you couldn’t tell the time unless the sun was shining!
The water clock, invented by the ancient Egyptians, was a great step forward. This consisted of two bowls, one on top of the other. The top one was filled with water, which dripped out into the bottom bowl through a tiny hole. When all the water had dripped through - a certain period of time had passed. Large water clocks ran for six hours and then had to be re-filled. The famous Greek philosopher Plato constructed one of the first alarm clocks using one of these Egyptian water clocks. He hung the bottom part of the water clock on a swivel, so that after a certain time it would tip over and pour out all the water. The water was then channeled along to a whistle, which would begin to blow as the water streamed through it.
The water-clock was modified into the hour-glass. At first, the hour-glass contained water which dripped through the narrow opening between an upper and lower vessel; the device was later improved by replacing the water with very fine sand. The length of time taken for the upper glass to empty was carefully measured and when the water (or sand) had all reached the bottom, the hour-glass was reversed. Erone, a great physicist who lived about 200 B.C. used an hour-glass for taking the pulse of his patients. At Greek trials the time allowed to the defendant for pleading his case was limited by the hour-glass.
Another method of time-telling used by the Romans was to burn candles marked to indicate the passing of the hours, and rich people could buy pocket sun-dials. Then, about 130 B.C., Ctesibius, a mathematician, had the brilliant idea of constructing an hour-glass in which the action of the dripping water set in motion a system of wheels. These, in their turn, were connected to a little statue, which slowly climbed a notched column, marking off the hours on it with a stick.
The Chinese used other methods to build their clocks. For example, they would mark incense sticks off into certain periods of time. There is a record of a very artistic Chinese making a “smell” clock, which gave off a different scent each time a certain period had passed.
The ancient Germans had an exhausting method of keeping track of the time. They would fill a helmet full of pebbles, and then transfer them, one by one, into another helmet. You can imagine how the period of time taken to transfer the pebbles would vary depending on the mood of the man doing the work!
