XVI. THE EARTH AS A PLANET 



DAY AND NIGHT, AND THE EARTH'S ROTATION 



1. When the sun rose this morning, in what direction was 

 it from due east ? (Be ready when called upon to point out 

 where the sun rose.) About what time was it? What is 

 the time now ? 



Where is the sun now? What has it done (apparently) 

 since you first saw it this morning? In what direction will 

 it be at sunset to-night ? Why do you think so ? What do 

 you ordinarily mean by (a) sunset ; (6) sunrise ? 



Where will the sun be to-morrow morning? Why is it 

 reasonable to expect this? 



2. What is the common distinction between daytime and 

 nighttime? Why is the nighttime better for sleep, and 

 the daytime better for our varied activities? Name some 

 occupations in which men labor all night, and sleep by day. 



How many hours in a day (both daytime and night- 

 time) ? From what time to what time may the length of a 

 day be best measured? What fractional part of such a 

 period is an hour? How are the lengths of minutes and 

 seconds determined? Calculate how many minutes there 

 are in a day (24 hours). 



3. Hold a cardboard edgewise against the right side of 

 the face, thus shutting out of sight objects far around on 

 that side. Turn slowly towards the right without change 

 of standing place, and state (a) what is found true of the 



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