28o THE POPULAR SCIENCE MONTHLY 



TIME AND SPACE 



By CHARLES W. SUPER 



ATHENS, O. 



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. Eailroad trains 

 and steam vessels are run according to time schedules. Offices are 

 opened and closed at certain hours. Employees of all classes are re- 

 quired 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 fu- 

 ture 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 obser- 

 vation. 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 dis- 

 tances, 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 an- 

 tiquity. 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 



