STANDARD TIME 



31 



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 posses- 



MAP SHOWING STANDARD TIME BELTS. 



sions, 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 important places near these. 



Experiment 10. On a day when there appear to be indications of 

 settled fair weather place a table covered with blank paper in an 

 open space where the sun can shine upon it. Make the top of the 

 table level and fix it firmly so that it cannot be moved. Fix vertically 

 upon the table a knitting needle or a slender stick. Mark the line of 



