INTERNATIONAL DATE LINE 35 



same city, these different times became very confusing. 

 Therefore in 1883 the American Railway Association per- 

 suaded the Government to adopt Standard Time. 



A certain meridian was adopted as the time meridian 

 for a definite belt of country. The meridians adopted 

 were 75 for Eastern, 90 for Central, 105 for Mountain, 

 120 for Pacific Time. These meridians run through the 

 centers of the time belts and for 7J on either side the time 

 used is the local time of the central meridian. When a 

 person crosses from one belt to another he finds that the 

 time makes an abrupt change of an hour. This system has 

 been extended to all the United States possessions, and is 

 coming into general use over a large part of the world. 

 In actual practice the changes of time are not made where 

 the boundaries of the time belts are crossed, but at im- 

 portant places near these. 



International Date Line. If a person should start at 

 noon and travel around the earth from east to west as fast 

 as the sun does, the sun would be overhead all the time and 

 no solar day would pass for the traveler, even though 24 

 hours would be required for the trip. But when he reached 

 home he would find that a calendar day had passed. This 

 shows the necessity of having some generally accepted north 

 and south line on the earth's circumference from which 

 to reckon the beginning and the ending of a day. 



Since the earth rotates once on its axis (the full 360 de- 

 grees of its circumference) in 24 hours, it turns in one hour 

 A- of its circumference, or 15 degrees. Places on the earth's 

 surface that are 15 degrees apart in an easterly-westerly line 

 may, therefore, be regarded as an hour apart in time. Since 

 the meridian of Greenwich is usually considered the Meri- 



