i HISTORY OF 



it could not easily be repaired; but it is composed of mauj 

 layers, each somewhat in itself resembling a feather, and lying 

 against each other in close conjunction. Towards the shaft of 

 the feather, these layers are broad, and of a semicircular form, 

 to serve for strength, and for the closer grafting them one against 

 the other when in action. Towards the outer part of the vane, 

 these layers grow slender and taper, to be more light. On their 

 under-side they are thin and smooth, but their upper outer-edge 

 is parted into two hairy edges, each side having a diiferent sort 

 of hairs, broad at bottom, and slender and bearded above. By 

 this mechanism, the hooked beards 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 contem- 

 plating an animal that flies, is the wing, the instrument by which 

 this wonderful progression is performed. In such birds that 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 itself. They answer to the fore-legs in quad- 

 rupeds, 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 furnished 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 

 contribute to the progressive motion of the bird, and the close- 

 ness of the wing. The manner in which most birds avail them- 

 selves 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 impulse, till it spreads the wing for 

 a second blow. For this reason we always see the birds choose 

 to rise against the wind, because they have thus a greater body 

 of air on the under than the upper side of the wing. For these 

 reasons also large fowls do not rise easily ; both because they 

 have not suflicient room at first for the motion of their wings, 



