22 



GENERAL SCIENCE 



found his timepiece' always too fast or too slow according 

 to the direction in which he journeyed. To avoid this 

 confusion the American Railway Association in 1883 

 persuaded the government to adopt standard time. 



By this plan the United States is divided into four 

 time sections, or belts. .Certain meridians 15 apart in 

 longitude and one hour apart in time are taken as 



FIG. 19. Standard Time Belts in the United States. 



standard. Each belt uses the mean solar time of its 

 standard meridian. Only the middle of the belt has 

 the true time by the sun ; other parts of the belt differ 

 from the sun's time in periods of from one to thirty 

 minutes. 



The names of the four time belts are the Eastern, 

 Central, Mountain, and Pacific, each extending for ap- 

 proximately 7 on each side of the meridians numbered 

 respectively 75, 90, 105, and 120 west of Greenwich 



