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Science project idea on how time is calculated.
How Time is Calculated Science Project Idea
 How time is calculated. Some of us must have been surprised when we received news of the signing of the Peace Treaty before the time scheduled for the event to occur in Paris. Then we were told that the time at Paris was five hours faster than our own time; that when it is noon at Paris, our 7 o'clock morning whistles are blowing; and when we stop work for luncheon, the people of Paris and London are ready to quit work for the day, as it is 5 P.M. with them.
The general difference in time between different places may easily be understood when we consider that one complete rotation of the earth makes one day of 24 hours,  and that noon by sun time at any place is the time when the sun is directly over a north and south line running through that place. In what direction does the earth rotate? In which city, New York or San Francisco, will 12 noon of a certain day first occur? For convenience in comparing times and for the purpose of locating places on the earth's surface, imaginary lines (meridians) are supposed to be drawn around the earth from pole to pole (Figure 158). There are 360 of these equally distant from one another. Why 360? The distance between these lines is called a degree of longitude. Is a degree of longitude always of the same length in miles? At the equator a degree of longitude measures about 69 miles. How much does a degree of longitude measure in miles at the poles? Usually the meridian passing through Greenwich, England, is called zero, and longitude is stated as east or west of Greenwich.
Since the earth rotates on its axis once in 24 hours, how many degrees of longitude will pass under the sun in an hour ? Thus, for every 15 of longitude, the sun time of two places differs one hour. If our clocks were set strictly by sun time, what would be true of the clock time of every place east and west of a given place? In what way would this be inconvenient? To prevent the trouble and annoyance arising from such a condition, the United States Government in 1883, at the suggestion of the American Railway Association,  adopted standard time. By this arrangement the time of the following meridians, 75th, 90th, 105th, and 120th, were taken as standards of time called Eastern, Central, Moun-tain, and Pacific Time. The area of the country to which the time was assigned extended approximately 1 degrees on each side of the standard meridian; the exact division being determined largely by the location of important cities. As a result, in going from New York to Chicago, we need to change our watches only once. Should the hands of the watch be advanced or turned back ? How much? Daylight saving. On March 19, 1918, President Wilson approved a bill passed by Congress, by which the standard time throughout the United States was advanced one hour for the period beginning at 2 A.M. on the last Sunday in March and ending at 2 A.M. on the last Sunday in October. Suggest advantages of this bill to the various classes of people of your community. Does it seem to work a hard- ship to any? During the summer of 1919, because of objection to the daylight-saving plan by various interests of the country, Congress repealed the bill. The movement originated in England in 1907. It was not until 1916, however, that definite action was taken, when within three months daylight saving was adopted in England, France, Italy, Norway, Sweden, Denmark, Switzerland, Spain, Portugal, Holland, Germany, Austria, and Turkey. Practically no confusion resulted; everything went on as before, people doing exactly the same things at the same time by the clock, but in reality the whole routine of life had been brought one hour nearer sunrise. The scheme had brought about in the simplest way a vital change affecting millions. A simple "twist of the wrist" had given these nations their "place in the sun." Friends of the movement in America claim that the annual conservation of coal in the United States would amount to no less a sum than $40,000,000 per season.
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