BIRDS IN GENERAL. 29 



as ffve for the most part under cover, are not furnished with so largo 

 a stock of this fluid, as those birds that reside in the open air. Th* 

 feathers of a hen, for instance, are pervious to every shower ; on the 

 contrary, swans, geese, ducks, and all such as nature has directed to 

 live upon the water, have their feathers dressed with oil from the very 

 first day of their leaving the shell. Thus their stock of fluid is equal 

 to the necessity of its consumption. Their very flesh contracts a fla- 

 vour from it, which renders it in some so very rancid, as to make it ut- 

 terly unfit for food ; however, though it injures the flesh, it improves 

 the feathers for all the domestic ourposes to which they are usually 

 converted. 



Nor are the feathers with which birds are covered, less an object of 

 admiration. The shaft of every feather is made proportionably strong ; 

 but hollow below for strength and lightness, and above filled with a 

 pith to feed the growth of the vane or beard that springs from the 

 shaft of the feather on either side. All these feathers are placed gene- 

 rally according to their length and strength, so that the largest and 

 strongest feathers in flight have the greatest share of duty. The vane 

 or beard of the feather is formed with equal contrivance and care. 

 It consists not of one continued membrane ; because, if this were 

 broken, it could not easily be repaired ; but it is composed of many 

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

 each other in close conjunction. Towards the shaft of the fea- 

 ther, these layers are broad, and of a semicircular form, to serve for 

 strength, and for the closer grafting them one against another when 

 in action. Towards the outer part of the vane, these layers grow 

 slende.r, and taper, to be more light. On their underside they are thin 

 and smooth, but their upper outer-edge is parted into two hairy edges, 

 each side having a different 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 contemplating 

 an animal that, flies, is the wing, the instrument by which this wonder 

 ftil progression is performed. In such birds as fly, they are usually 

 placed at that part of the body which serves to poize the whole, and 

 support it in a fluid that at first seems so much lighter than itself. 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-icing. This instrument of flight is furnished with quills, which 

 difier from the common feathers only in their size, being larger, and 

 also from their springing from the deeper part of the skin, their shafts 

 ying 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 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 

 bo^y 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 

 squal violence on the upper side as they rise, the wing is instantly 



