6 HISTORY or 



of one layer always lie next the straight beards of 

 the next, and by that means lock and hold each 

 other. 



The next object that comes under consideration 

 in contemplating an animal that flies, is the wing, 

 the instrument by which this wonderful progres- 

 sion is performed. In such birds as fly, they are 

 usually placed at that part of the body which 

 serves to poise the whole, and support it in a 

 fluid that at first seems so much .lighter than it- 

 self. They answer to the fore-legs in quadrupeds, 

 and at the extremity of this they have a certain 

 finger-like appendix, which is usually called the 

 bastard-wing. This instrument of flight is furnish- 

 ed with quills, which differ from the common 

 feathers only in their size, being larger, and also 

 from their springing from the deeper part of the 

 skin, their shafts lying almost close to the bone. 

 The beards of these quills are broad on one side, 

 and more narrow on the other, both which con- 

 tribute to the progressive motion of the bird and 

 the closeness of the wing. The manner in which 

 most birds avail themselves of these is first thus : 

 they quit the earth with a bound, in order to 

 have room for flapping with the wing ; when they 

 have room for this, they strike the body of air 

 beneath the wing with a violent motion, and with 

 the whole under surface of the same ; but then, 

 to avoid striking the air with equal violence on 

 the upper side as they rise, the wing is instantly 

 contracted ; so that the animal rises by the im- 

 pulse till it spreads the wing for a second blow. 

 For this reason, we always see birds choose to 



