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European-American Topics - Technology  - Time

It was not a waste of Time
Compiled by Fritz Burmeister

Posted September 7, 2006


Daniel Webster defines time as a period or an interval between two events during which something exists, happens or acts. These events may be measurable in centuries, days or microseconds, provided one has the appropriate tool to conduct the measurement. 

The clock is such an instrument with which to measure time in hours, minutes and seconds; modern calendar watches also display the date. But man was not always so lucky as to find a new timepiece under the Christmas tree or to receive one as a token of appreciation for umpteen years of faithful service from his employer. No, time measuring devices had to be developed and constantly improved and updated by successive inventions, until the accuracy of a modern atomic clock was established to be a loss or gain of one second in 20 million years!! 

Primitive man was able to tell time in nature. Light and darkness gave him the time of day; a new moon the beginning of a month and the change in the seasons with their varying daylight hours gave him the rhythm of the year. With no flight to catch and no doctor’s appointment to keep, that was sufficient for him to carry out his daily routine. In time, his observations of the movements of the heavenly bodies lead him to the invention of the sundial, where the shadow of a stick in the ground moves in accordance with the sun traversing across the sky. Obviously, this ancient forerunner of an instrument that eventually put man on a timed schedule was discarded from further development because of its uselessness during the night and on overcast days.

The old Egyptians advanced the development of time keeping devices a step further, by introducing a water clock, called the “Clepsydra.” In it, the water in a vessel is allowed to drip out of an opening, lowering the water level in the vessel at a near constant rate. The change in level, therefore, can be translated into time elapsed. Not being dependent on time of day or weather conditions, the water clock was definitely an improvement over the sundial. And as long as accuracy was not an issue, dynasties weren’t measured in seconds; the clepsydra must have served the old pyramid builders well enough.

Searching through the literature failed to identify the inventor of the first mechanical clock. Clocks seem to appear, however, in a number of European countries in the Middle Ages, primarily in monasteries, cathedrals and municipal buildings. Bulky as these primitive devices were, they nevertheless revealed that the clockmakers were on the right track to the development of an “escapement” mechanism, that eventually provided the sought after accuracy. The loss or gain of a quarter of an hour per day was the best their inventive labor could produce.

The escapement is the function that allows clock mechanisms to turn gears only a controlled amount in a specific amount of time, for instance a degree of rotation per second. The “Foliot” was the first escapement mechanism incorporated into mechanical clocks in the Middle Ages. This mechanism was a set of weight driven gears rotating by a certain amount, first in one direction and then in the opposite, counterbalanced by a horizontal cross arm to which weights were also attached.  Clocks with this early escapement mechanism were bulky due to the elaborate construction and it is understandable why they were primarily housed in clock towers. Greater accuracy was not possible until the advent of the next generation of clocks, namely the pendulum clock, which has survived the ages into our time, the grandfather clock and the cuckoo clock are familiar examples still found in many households.

The breakthrough came when a Dutch scientist named Christiaan Huygens in 1656 realized that an accurate oscillatory function is needed if his clock is to keep accurate time. He remembered that Galilei had established the laws of the pendulum a hundred years earlier. He had found that the period of the pendulum (one complete swing) is dependent only on its length. By making the pendulum part of the escapement mechanism Huygens found the solution to a problem that had eluded contemporary clockmakers.

In a pendulum clock the energy required for movement of gears and to overcome friction is typically supplied by a suspended weight, which is attached to a gear train. However, the gravitational force would cause the weight to descend rapidly toward earth in accordance with the laws of free falling bodies, thereby expending the potential energy needed to move the hour, minute and second hands only a small amount at a time. Huygens escapement consisted of the escapement gear and the pendulum, rigidly attached to the anchor. The escapement gear, energized by the suspended weight, gives the anchor a small boost by virtue of the interconnecting teeth, causing the attached pendulum to swing in one direction and the gear to advance a small amount until, on the return swing of the pendulum, the tooth on the opposite side of the anchor drops into a notch of the escapement gear. That stops the movement momentarily. The pendulum, now returning to its original position, moves the anchor such that the locking tooth is released, receives another nudge on the opposite side to sustain the action. Bingo, time had come for man to schedule his activities.

An early attempt to reduce the size of a clock to make it even portable goes back to 1510 when Peter Henlein, a Nuremberg mechanic, was able to incorporate a steel spring as the energy source of his “pocket watch.” Still somewhat bulky and lacking the accuracy, which the pendulum clock later, achieved, Henlein’s innovation nevertheless could run for forty hours without rewinding. Stuffing the clockworks into a relatively small container entitled Henlein a place on the list of forgotten inventors.

But time does not stand still, nor does the human mind rest in opening up new frontiers in science and technology. Electricity, when it became available, steered the inventive mind of clockmakers to use this newly found inexhaustible pool of energy as the driving force for a new generation of clocks. Early electric clocks were driven by a synchronous motor that was in ”synch” with the frequency of the applied alternating current. Other methods made use of the magnetic force, created when an electric current flows through a conductor, to move gears that allows the hour, minute and second hands to move at the specific rate. A detailed description of the various applications of electrical energy including digitizing the clock face and miniaturizing the mechanism, so women could wear petite, but hard to read wrist watches with their fancy outfits, will not be attempted here, because of the complicity.

Through research and development clocks and watches have undergone changes in size and appearance as well as in improvements in accuracy. But the principles of design features have not changed since the early beginnings. Basic components, a weight, spring or electric power is still needed for an energy source, an oscillation device such as the pendulum or a quartz crystal, as used in modern watches, is still needed, and interconnecting gears to provide the timed movement of the hands, is equally essential. Even the atomic clock, whose latest version began operation for the National Institute of Standards and Technology in 1999, requires an oscillator. In this case it is the vibrating motion of the nucleus of an atom and its orbiting electrons.

Life today without clocks and watches is unthinkable. We have watches, probably several of them, a clock in every room and a clock in the automobile. Coffee makers and other appliances come with a timing device nowadays, needed or not. Some people pride themselves in displaying an expensive watch, others do not. An acquaintance bought a wristwatch to the tune of $ 24,000! It is probably doubtful that in the routine of his daily life he needs time told more accurately than the guy with a Mickey Mouse watch.

The development of the clock is a fascinating story. It is particularly amazing to note how clockmakers in the Middle Ages have schemed and labored to come up with a usable timing device when all parts had to be made by hand. From Peter Henlein’s “pocket watch” and Huygen’s pendulum clock to the atomic clock lie hundreds of years -a long time. According to Webster it was a period in which something happened.


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