Page:Popular Science Monthly Volume 80.djvu/284

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IT requires but a moment's reflection on the part of any one in the least familiar with modern affairs to realize that the time element has come to be the most important factor in business. Railroad trains and steam vessels are run according to time schedules. Offices are opened and closed at certain hours. Employees of all classes are required to report for duty according to the clock, and their task is not completed until they have put in a fixed number of hours. New devices are constantly being placed on the market the purpose of which is to "save time" as the phrase goes. The importance that our day attaches to time is strikingly shown by the fact that for a decade Switzerland has manufactured from six to eight millions of clocks and watches annually; yet this is but a small part of the world's output. It is safe to say that on the average every adult in the United States and in the most civilized countries of Europe is the possessor of a time-piece of some sort. Time may be conceived under two aspects: it may mean a continuous current of duration flowing past a point which we call the present; or it may signify some fixed point or points in that current and the period between them. Remote time either in the past or in the future is usually designated by the term eternity. Any one who reflects soon comes to realize that he can form no concept of duration without beginning or end because it lies out of the range of experience and observation. The popular use of the word time refers exclusively to shorter and longer divisions or units within endless duration, as when we say: "I have not time to talk of this now"; "that never happened in my time"; "the train is on time." The same statement may be made of space. Although it extends in every direction to inconceivable distances, in practical affairs only that part of it is important which can be measured. What is generally called "nature" furnishes us with no accurate standard of measurement of either time or space. For the former the rotation of the earth on its axis gives us an almost uniform period which from time immemorial has been divided into twenty-four hours. No one has ever been able to explain why this number was chosen rather than some other, but it is wholly artificial. Not only this period, but its smaller units, had to be marked by some technical means. For this purpose water-clocks were invented in a remote period of antiquity. The oldest of which any information has been transmitted to us were in use in Egypt as early as 300 B.C. They consisted of a