260 THE STORY-BOOK OF SCIENCE 



day for the half of the lark next to the fire, and night 

 for the other half." 



"One difficulty still perplexes me," Jules' contin- 

 ued. "If the earth turns around once in every 

 twenty-four hours, in half of that time we ought to 

 make a half-turn with the globe that carries us, and 

 find ourselves upside-down. At this moment we 

 have our heads up, feet down ; twelve hours later it 

 will be just the opposite : our heads will be down and 

 our feet up. We are upright, we shall be upside- 

 down. In that inconvenient position why don't we 

 feel uncomfortable ? Why are we not thrown down I 

 So as not to fall, it seems to me, we ought to be 

 obliged to cling to the ground in desperation." 



"Your observation is right," returned Uncle Paul, 

 "but only in a certain degree. Yes, it is true that 

 twelve hours from now we shall be in an inverse posi- 

 tion ; our heads will be toward that point in space to 

 which our feet are now turned. But despite this in- 

 version there will be no danger of our falling, nor 

 even the slightest inconvenience of any kind ; for our 

 heads will always be up, that is to say toward the 

 sky, since the sky surrounds the terrestrial globe 

 everywhere ; our feet will always be down, that is to 

 say resting on the ground. Understand thoroughly, 

 once for all, that to fall is to rush toward the ground, 

 and not into surrounding space. So that notwith- 

 standing all the evolutions of our globe, as we are 

 always on the earth, feet on the ground, head toward 

 the sky, we are always in an upright position, with- 

 out any unpleasant feeling, without any danger of 

 falling." 



