THE SEASONS AND THE SOLAR SYSTEM 177 



spring and summer, of autumn and of winter. What are 

 some of the things that we call "signs of spring," or "signs 

 of whiter"? 



QUESTIONS 



1. Why is our longest day not also our hottest day? 



2. What is the " solar system "? 



3. Describe the movements of the earth, and explain what rela- 



tion they have to days and years. 



4. In what direction does the earth rotate? 



5. What is the cause of the seasons? 



6. What are the equinoxes? 



7. What are parallels and meridians? 



8. What are the tropics? the arctic and antarctic circles? 



