HomeboyMediaNews

Let’s take a closer look at the different types of clocks as they evolved through centuries of diverse civilisations.

‘Time is money’. Haven’t you heard this statement very often? From our childhood we are taught to value time and not to waste it carelessly. In today’s fast hi-tech life all our voluntary activities, from eating to sleeping, are performed minute-by-minute according to the clock. Today, it is unthinkable to function without our time-measuring machines.
It is interesting to find out how the measurement of time first began. We know that time was first split into day and night and finally into various units of time. The history of time-keeping is the story of the search for even more consistent actions to regulate the rate of a clock.

All clocks must have two basic components: a repetitive process to mark off equal increments of time. Early examples of such processes included movement of the sun and stars, increment marked candles , oil lamps with marked reservoirs, hourglasses and in the Orient, small stone mazes filled with incense that would burn at a certain pace.
These were means of keeping track of increments of time and displaying the result. Our means of keeping track of time include the position of clock hands and a digital time display. So, from huge ancient sun-dials to contemporary atomic clocks, here’s something to interest you.

Sun Dials: Egyptians were amongst the first few people to have developed a clock to measure the passage of time. Obelisks, which were slender, tapering, four-sided monuments were built as early as 3500 B.C. Their moving shadows were used to decide the time. They also showed the year’s longest and shortest day when the shadow at an Egyptian sundial, possible the first portable timepiece, came into use around 1500 B.C. This device divided a sunlit day into 10 parts, plus two twilight hours in the morning and evening. In the quest for more year-round accuracy, sundials evolved from flat horizontal or vertical plates to forms that were more elaborate. By 30 B.C. 13 different sundial styles could be described in use in Greece, Asia Minor, and Italy. However, the most serious drawback of the sundial was that it became ineffective in cloudy weather and nights. People therefore were attracted to other means.

Merkhets: The merkhet, the oldest known astronomical tool, was an Egyptian development of around 600 B.C. Two merkhets were used to establish a north-south line by lining them up with the Pole star. They could then be used to mark off night time hours by determining when certain other stars crossed the meridian. This system too was not very welcome as it proved to be useless during the day and on cloudy nights.

Water Clocks: Water clocks were among the earliest timekeepers that did not depend on the observation of celestial bodies. One of the oldest of this type was found in the tomb of Amenhotep I, buried around 1500 B.C. These were stone vessels with sloping sides that allowed water to drip at a nearly constant rate from a small hole near the bottom. Markings on the inside surface measured the passage of time as the water level reached them. Another version of this clock consisted of a metal bowl with a hole at the bottom. More impressive mechanised clocks were developed between 100 B.C. and 500 A.D. by Greeks and Romans. Some water clocks rang bells and gongs; others opened doors and windows to show little figures of people, or moved pointers, dials, and astrological models of the universe. Since the rate of flow of water is very difficult to control accurately, a clock based on that flow could never achieve proper accuracy. People were naturally led to other approaches.

Candle Clocks: A candle clock is a thin candle with consistently spaced markings, which when burned, indicates the passage of periods of time. Candle clocks provided an answer on cloudy days. In the 9th century A.D. King Alfred the Great of England used graduated candles to divide day into equal periods of study and prayer, royal duties and rest.

Incense Clocks: During the Sung dynasty in China, sticks of incense measured time. In one 18th century incense clock, six threads with weights on either end were draped over an incense stick at regular intervals. At the incense burned, the threads burned one by one, and the weights dropped to a sounding plate below. Sticks of incense with different scents were also used, so that the hours were marked by a change in fragrance. This clock too could be used in nearly all conditions.

Sand Clocks: Also known as the “Hourglass”, it functions on more-or-less the same principle as that of a water clock. Sand is allowed to fall from one vessel into the other and the period taken is used to measure time. It must have a rate of flow that does not fluctuate. These clocks were used in the 18th century and is still in use as decorative items. It is independent of weather conditions and hence proved to be of wider use.

Mechanical Clocks: In 1656, Christian Huygens, a Dutch scientist, made the first pendulum clock with a mechanism using the natural period of oscillation. Huygens’ clock, when built, had an error of less than only one minute a day. This was a massive leap in the development of maintaining accuracy, as this had previously never been achieved. Later refinements to the pendulum clock reduced the margin of error to less than 10 seconds a day. Huygens, in 1657, developed what is known today as the balance wheel and spring assembly, which is still found in some of today’s wrist watches. The mechanical clock continued to develop, bringing a new revolution in the world of time.

Atomic Clocks: Scientists discovered some time ago that atoms and molecules have resonances and that each chemical element and compound absorbs and emits electromagnetic radiation within its own characteristic frequencies. The development of atomic clocks focused firstly on microwave resonances in the chemical ammonia and its molecules. The natural frequency recognised currently in the measurement of time, used by all scientists, defined the period of one second as exactly 9, 192, 631, 770, oscillations. From the ‘Macrocosm’, or ‘Planetary Alignment’, to the ‘Microcosm’, or ‘Atomic Frequency’, the caesium now maintains an accuracy with a degree of error to about one-millionth of a second per year.

Much of modern life has come to depend on extremely accurate measurements of time. The day is long past when we could get by with a timepiece accurate to the nearest quarter hour. Transportation, financial markets, communication, manufacturing, electric power and many other technologies have become dependent on super-accurate clocks.