TIME 



71 



3. 1002:177-180. 



4. 1304:6-8. 



a. 1001 : 47-50. 

 6. 1001:70-71. 



c. 1003:32-44. 



d. 1301:13-17. 



e. 1301:66-68. 

 /. 1302 : 17-19. 

 g. 1303:6-7. 

 h. 1305:43-44. 

 i. 1305:51-52. 

 j. 1307:18-19. 

 k. 1309:25-28. 



I. 1310:308-311. 

 m. 1311 : 19-26. 

 n. 1312 : 19-24. 



The Seasons. 



Motions of the Earth. 



Effects of the Rotation of the Earth. 



The Earth's Orbit. 



The Revolution of the Earth round the Sun. 



Rotation, Revolution, and their Effects. 



Effects of Rotation and Revolution. 



Rotation and Revolution of the Earth. 



Rotation of the Earth and its Consequence. 



Motions of the Earth. 



Days, Nights, and Seasons. 



Effects of Rotation. 



Rotation and Revolution and their Effects. 



Rotation and Revolution of the Earth. 



The Year, Day, and Night. 



Revolution and Rotation and their Effects. 



51. TIME 



The motions of the earth furnish the natural divisions of 

 time day and night, and the year. One complete turning 

 of the earth on its axis causes day and night, while the trip 

 around the sun results in the march of the seasons. See Sec- 

 tion 52 for a discussion of the seasons and their causes. The 

 revolution of the moon around the earth gave us the month, 

 until man discovered that the moon made more nearly thir- 

 teen than twelve trips per year. The week is an artificial 

 division of time, and is not founded upon any natural cause. 



Since the earth revolves 360 in twenty-four hours, it moves 

 at the rate of 15 an hour. Therefore two places which are 

 15 apart, east and west, have a difference in time of one hour. 

 This led to considerable trouble when railroads and the tele- 

 graph brought places nearer together, and Standard Time was 

 devised to prevent misunderstandings. 



