116 OUR HUMBLE HELPERS 



leader of the file. Is it not true that under these 

 conditions the sum total of fatigue will be the least 

 possible ! ' ' 



"All that is obvious," Emile replied. "They 

 could even, if it were a long way through the brush- 

 wood, take turns in going ahead, and then no one 

 would be really tired out." 



"This device of Emile 's has, as you already know, 

 been put in practice from time immemorial by ducks 

 on their long flights. Nor is the goose less happily 

 inspired. If the flock is a small one, the birds com- 

 posing it range themselves in a continuous single 

 file, each following bird touching with its beak the 

 tail of the preceding one, in order that the way 

 opened through the air may not have time to close 

 again. If the flock is numerous, two files of equal 

 length are formed, and they join each other at an 

 acute angle, advancing point first. This angular 

 arrangement, which we find imitated in the ship's 

 prow, in the farmer's plowshare, in the thin edge 

 of a wedge, and in any number of utensils fashioned 

 for penetrating a dense mass by overcoming re- 

 sistance, is the one best suited for cleaving the air 

 with the least possible fatigue. If, to arrange its 

 flying squadron, the goose had taken counsel of the 

 most consummate science of our engineers, it could 

 not have done better. But the goose has no need of 

 others; advised by its instinct, it knew long before 

 us, who call it stupid, one of the great secrets of 

 mechanics, the principle of the wedge. 



"Moreover, to divide among all the members of 



