i>(> THE STORY-BOOK OF SCIKNCK 



low; July, bump. And now? I am at the end of 

 my hand." 



"Now begin again and go on naming the months," 

 I'nele Paul instructed him. 



44 You go on at the same point where you began f n 



"Yes." 



"All right. August, bump. There are two 

 bumps in succession. There are then two months 

 together, July and August, that have 31 days?" 



"Yes." 



"I will begin again. August, bump; September, 

 hollow. September has 30 days." 



"Why has February sometimes 28 and sometimes 

 L'!> days?" asked Claire. 



' ' I must tell you that the earth does not take ex- 

 actly 365 days to turn around the sun. It takes 

 nearly six hours more. To make up these six hours 

 that were disregarded at first in order to have a 

 round number of days in the year, they are reckoned 

 in every four years, and the additional day they make 

 all together is added to February, which then be- 

 comes 29 days long instead of 28." 



"So, for three years running, February has 28 

 days, and the fourth year it has 29." 



"Exactly. Kemember, too, that the years when 

 February has 29 days are called leap years." 



"And the seasons?" queried Jules. 



"For reasons that would be a little too difficult for 

 you to understand yet, the annual journey of the 

 earth around the sun causes the seasons and the 

 unequal length of days and nights. 



"There are four seasons, of three months each: 



