THE STORY-BOOK OF SCIENCE 



ceiving the tops of the masts, then the topsails, then 

 the sails next below, and finally the hull of the ves- 

 sel. If the vessel were departing from the shore, 

 the observer would see it gradually disappear and 

 apparently plunge under the water, all in inverse 

 order; that is to say, the hull would be first hidden 

 from view, then the low sails, then the high ones, and 

 finally the top of the mainmast, which would be the 

 last to disappear. Four strokes of the pencil will 

 make you understand it. ' ' 



"How large is the earth I " was the next question 

 from Jules. 



1 ' The earth is forty million meters in circumfer- 

 ence or 10,000 leagues, for a league measures four 

 kilometers. To encircle a round table, you take hold 

 of hands, three, four, or five of us. To encircle in 

 the same manner the vast bosom of the earth, it 

 would take a chain of people about equal to the whole 

 population of France. A traveler able to walk day 

 after day at the rate of ten leagues a day, which no 

 one could do, would take three years to girdle the 

 globe, supposing it to be all land and no sea. But, 

 where are the hamstrings that could resist three 

 years of such continual fatigue, when a walk of ten 

 leagues generally exhausts our strength and makes 

 it impossible for us to begin again the next morn- 

 ing?" 



