THE EMPIRE OF THE AIR. 



431 



its wings. Changes of i)lane against the air w hich change the diieetion 

 of its tligiit Avith incredible celerity. No other tlying creatnre has this 

 gift ei^nally developed. 



With what astonishment is the tiight of this enormons bird beheld 

 u nder tlie trees ! I^o snch (h'xterity can be re-called. Theobser\-er's habit 

 being to see birds generally proceeil in a straight line, it renders the 

 flight of the great-eared owl fairly stupefying; it seems at every mo- 

 ment as if it were about to dash against a tree, and yet every obstacle 

 is avoided. It Hashes silently, horizontally, or even vertically through 

 spaces where there would seem to be no passage; and this is done with 

 absolute mechanical precision, without hesitation or slackening of speed. 



This is truly the most extraordinary mode of tiight, but it is a rare 

 sight even to dwellers in the country. 



77/e Gull type. — This genus teaches one thing, namely, that in order 

 to hover or to penetrate in great currents of wind, the resistance of the 



Fig. ;t.- riic Kinnlisher. 



a-rophnie must be reduced to a mininnim. The si)read (»f wing is of 

 h!Ssc(Misequence than its width. W'lu'n we think of it this is rational, 

 but it must be confessed that nature did well to demonstrate it. for it 

 was a difficult deduction to get at. The table shows that in this type 

 th«i spreads of the wings is from (1 to 10 times their width. 



The albatross, which is not included, must greatly exceed this pro- 

 l)ortion, foT travelers mention scmie 16 or 17 feet as the extreme s|)rea<l 

 of wings, and as its width is about 10 inches we have for this bird a 

 l)roportion of about 1*0 to 1. 



This teaching is of great importance, and should b<> borne in mind 

 in the design of icroplanes with adjustable surfaces. 



