Our discussions of time have shown that "the time" when something happened or the "length" of time it lasted depends on the scale used for measurement. "Sun time" is different from "star time," and both differ from "atomic time." Sun time at one location is inevitably different from sun time only a few kilometers-or even a few meters-east or west.

A factory whistle blown at 7:00 in the morning, noon, 1:00 and 4:00 P.M. to tell workers when to start and stop their day's activities served many a community as its time standard for many years. It didn't matter that "the time" was different in each community. But in today's complex society, with its national and international networks of travel and communications systems, it's obvious that some sort of universal standard is essential. The establishment of Standard Time is much more recent than many persons realize.

STANDARD TIME ZONES AND DAYLIGHT-SAVING TIME

In the latter part of the 19th century a traveler standing in a busy railroad station could set his pocket watch to any one of a number of clocks on the station wall; each clock indicated the "railroad time" for its own particular line. In some states there were literally dozens of different "official" times-usually one for each major city-and on a cross-country railroad trip the traveler would have to change his watch 20 times or so to stay in step with the "railroad time." It was the railroads and their pressing need for accurate, uniform time, more than anything else, that led to the establishment of time zones and standard time.

One of the early advocates of uniform time was a Connecticut school teacher, Charles Ferdinand Dowd. Dowd lectured railroad officials and anyone else who would listen on the need for a standardized time system. Since the continental United States covers approximately 60 degrees of longitude, Dowd proposed that the nation be divided into four zones, each 15 degrees wide-which is the distance the sun travels in one hour. With the prodding of Dowd and others, the railroads adopted in 1883 a plan that provided for five time zones-four in the United States and a fifth covering the easternmost provinces of Canada.

The plan was placed in operation on November 18, 1883. There was a great deal of criticism. Some newspapers attacked the plan on the grounds that the railroads were "taking over" the job of the sun," and said that, in fact, the whole world would be "at the mercy of railroad time." Farmers and others predicted all sorts of dire results-from the production of less milk and fewer eggs to drastic changes in the climate and weather-if "natural" time was interfered with. Local governments resented having their own time taken over by some outside authority. And so the idea of a standard time and time zones did not gain popularity rapidly.

But toward the end of the second decade of the 20th century the United States was deeply involved in a World War. On March 19, 1918, the United States Congress passed the Standard Time Act, which authorized the Interstate Commerce Commission to establish standard time zones within the United States; and at the same time the Act established "daylight-saving time," to save fuel and to promote other economies in a country at war.

The United States, excluding Alaska and Hawaii, is divided into four times zones; the boundary between zones zigzags back and forth in a generally north-south direction. Today, for the most part, the time-zone system is accepted with little thought, although some people near the boundaries still complain and even gain boundary changes so that their cities and towns are not "unnaturally" separated from neighboring geographical regions where they trade or do business.

The idea of "daylight-saving time" has roused the emotions of both supporters and critics-notably farmers, persons responsible for transportation and radio and television schedules, and persons in the evening entertainment business-and continues to do so. Rules governing daylight-saving time have undergone considerable modification in recent years. Because of confusion caused by the fact that some cities or states chose to shift to daylight-saving time in summer and others did not-with even the dates for the shifts varying from one place to another-Congress ruled in the Uniform Time Act of 1966 that the entire nation should use daylight-saving time from 2:00 A.M. on the last Sunday in April until 2:00 A.M. on the last Sunday in October. (Actually "daylight-saving time" does not exist: there is only "standard time" which is advanced one hour in the summer months. "Daylight-saving time" has no legal definition, only a popular understanding.) Any state that did not want to conform could, by legislative action, stay on standard time. Hawaii did so in 1967, Arizona in 1968-(though Indian reservations in Arizona-which are under Federal jurisdiction-use daylight-saving time) and Indiana in 1971. In a 1972 amendment to the Uniform Time Act those states split by time zones may choose to keep standard time in one part of the state and daylight-saving time in the other, Indiana has taken advantage of this amendment so that only the western part of the state observes daylight-saving time.

When fuel and energy shortages became acute in 1974, it was suggested that a shift to daylight-saving time throughout the nation the year around would help to conserve these resources. But when children in some northern areas had to start to school in the dark in winter months, and the energy savings during these months proved to be insignificant, year-around daylight-saving time was abandoned, and the shifts were returned to the dates originally stated by the 1966 Uniform Time Act. In the long run the important thing is that the changes be uniform and that they apply throughout the nation, as nearly as possible.

The whole world is divided into 24 standard time zones, each approximately 15 degrees wide in longitude. The zero zone is centered on a line running north and south through Greenwich, England. The zones to the east of Greenwich have time later than Greenwich time, and the zones to the west have earlier times-one hour difference for each zone.

With this sytem it is possible for a traveler to gain or lose a day when he crosses the International Date Line, which runs north and south through the middle of the Pacific Ocean, 180° around the world from Greenwich. A traveler crossing the line from east to west automatically advances a day, whereas one traveling in the opposite direction "loses" a day.

Both daylight-saving time and the date line have caused a great deal of consternation. Bankers worry about lost interest, and law suits have been argued and settled-often to no one's satisfaction on the basis of whether a lapsed insurance policy covered sub