HISTORY OF MEASURING TIME

lion scratched on us served as a record but soon man noticed that the Sun as it traveled across the sky through a moving ship the direction of which divided the day into shorter time units units by which he could tell how much more daylight remain before nightfall the length and position of the moving shadow from a stick planted in the ground served the same purpose it was a crude version of what was later to be known as the sundial some trucks such as the sundial took many interesting forms among them this one popular in ancient Egypt here the angel length of the sun's shadow was measured and so told time and there's man depended on the Sun to measure off the day he depended on the position of the stars to measure off the night the stars rose in the east swung through the heavens and set in the West only to reappear the following night in Egypt men had come to know certain easily recognized groups of stars from their stargazing they painted time tables which told where these stars would be on any night of the entire year but few Egyptians have the knowledge and the skill to tell time in this difficult way and to make matters worse both the Sun and the stars were useless when the sky was overcast man needed something that would work at all times something that would tell time day and night clear or cloudy so various mechanical devices were invented to do the job like this one being used in all Egypt M is the background of our lives it regulates our every action it is universal ever-present but what is it and how can it be measured spring summer Paul winter the changing recurring season suggest the idea of time so just a way of measuring it the family with the young child mother who has lived longer climb or try to measure it we relate it to a series of happenings to a succession of events which will give it meaning perhaps the simplest most easily recognized succession of events is day and night therefore it was only natural that lightness and darkness was Man's first time peace with her many years they are evidence of the flow of time and of an order of events by which time can be measured this ancient redwood which was once for the stuff has seen countless generations and so becomes a yardstick of times time is mirrored in the march of history time is seen in the succession of man's labor [Music] time is seen in the movements of the oceans high tide and low tide golden egg decorated with intricate design opens to reveal a maze of dials often one some were heavy and plump some thin but as large as a saucer alarm or striking watches were great favor the modern watch a far cry from its pudgy ancestors has come into being modern manufacturing methods have given it amazing accuracy but at what speed Shelley's watch his run how do we know when they tell the right time against what standard shall our watches be checked to answer this we must return to nature the master clock to the Sun on its daily journey across the sky and to the regular movements of the stars through the night at dawn in early are the Egyptians noticed a group of stars just above the horizon of the eastern sky at dawn one week later they noticed that this same group of stars was slightly higher a month later these stars were still further ahead of the Sun finally after approximately 365 days because of this continuous advance they found the same group of stars again in the same position as during their first observation these things were observed but they were not understood until hundreds of years later when the astronomer Copernicus offered a simple and logical explanation he showed that the earth travels around the Sun once every year meanwhile it spins on its own axis like a top it is this spinning into and out of the sun's rays that creates day and night and as part of the earth moves into darkness the people on that side of the earth see group after group of stars come into view this lightly panorama of the firmament enables us to tell time by the stars for the stars as well as the Sun measure off time but some time suppose directly overhead at night is a star billions of miles away at another point on the earth to another observer the Sun is directly overhead the Earth turns exactly one revolution and meanwhile it moves a short distance and its trip around the Sun it is the next night the star is again directly overhead and the star day or Siberia day has elapsed at the other point on the earth however the observer does not find the Sun any longer directly overhead it takes the earth a little longer three minutes and 56 seconds to catch up this is a solar day the day of lightness and darkness by which we live but since it varies slightly from day to day our timepieces are checked for accuracy by the stars at elgin illinois home of fine american-made watches the hens of thousands of watches are continuously checked the telescope that relates time to the stars is built so that it can swing only in one direction north and south along the imaginary line called the celestial Meridian which is directly overhead in the sky in the lens system of this telescope is a web of lines these are reference lines and one of them is movable when the star to be observed called a clock star appears in vision critical line is moved under the control of a finely adjusted micrometer wheel the line cuts the star exactly in half and follows the star from east to west as the moving thread crosses the exact center of the field an electrical circuit is broken and the Stars movement is automatically recorded on the tape of a delicate electrical instrument the regular beats of the clock which tells side aerial time as perfect a timekeeping instrument as man's ingenuity has been able to devise are recorded on the same tape thus the record gives the rate of travel of the star according to the side aerial time clock this is compared with the correct entry in an elaborate set of Star tables which gives for every clock star the exact time it must appear on any day of the year by this unceasing check with nature the scrupulous accuracy of the side aerial time clock and its companion the mean solar time clock is assured to the hundredths of a second and from these faithful standards timepieces all over the world are set and checked and double-checked we have seen how human progress brought with it a stream of inventions carrying the telling of time from the sundial of the Ancients down to ever better mechanical devices at the same time man searching eyes have probed ever deeper into the heavens and his knowledge of the timetable of the universe has steadily increased today beating out with faithful regularity the unceasing motions of the stars is the modern watch today timepieces are a far cry from their earlier ancestors they are thinner neater less expensive and infinitely more accurate human ingenuity and the unchanging laws of nature have given us these timepieces to which all of our life is geared time is universal time guides the little things of everyday life time is the aid of the doctor and the scientists time guides the wheels of Industry time guides the complicated schedules of our transportation systems the slow escape of water from a leaking vessel suggested the water clock as the vessel slowly emptied the lowering water level gradually uncover every possible variety of shape material and decoration even the dial was given a series of beauty treatments until it became so ornate that it was almost impossible to read the numbers but in spite of all the guilt and enamel clocks were man-sized affairs they still had to be tall enough to hold a pendulum and to allow for the fall of the weight meantime clock makers had a field day unleashed a flood of new and often fantastic escapements let loose a host of unique variations of clock mechanisms along with these came to developments which led to smaller and better clucks her water was scarce or where it might easily freeze fine sand or powdered eggshell was used and this gave birth to the more complicated our glasses our glasses of many shapes and sizes for night owls there was a candle clock which literally burned away the hours and sometimes the shadow cast by the candle flame was used of course many things even a slight draft would raise havoc with the accuracy of these timepieces through the fall of the Roman Empire and the conquests of Charlemagne there was little improvement in the methods of telling time but out of the Renaissance which followed the Dark Ages came to tremendously important discoveries the first was a mechanism called the escapement in principle the escapement was very simple a falling weight on the spool or drum the drum was connected to a peg wheel and biting into this pegged wheel were two catches which allowed the wheel to revolve a little at a time the catcher's were connected to an arm which swung back and forth ticked-off time intervals as one tooth escaped the opposite tooth gave a little kick to the catch and so the swinging arm was kept in motion it was a crude device and not always reliable but it was far better than roughs of water or running sand or candle flame and from this came the tower clock the grandsire of all modern clocks following closely came the second great discovery of the Renaissance seated in the cathedral at Pisa the famed scientist Galileo was watching the slow swing of the great lamp using his heartbeat to time it he noticed that the lamp always took the same length of time for a trip back and forth regardless of how far it's swung as Galileo what he saw it as a simple swinging weight a pendulum a pendulum follows a simple law for a given length that always takes the same time for a trip regardless of how far its wings this made-to-order time spacer was applied to a clock mechanism and as such the pendulum as it swings literally bites off equal intervals of time which can be lengthened or shortened by setting the length of the pendulum this marked the beginning of a long period of popularity for pendulum clocks cabinetmaker