BIRDS. 137 



The external apparatus of birds is not less the object 

 of just admiration, than their shape and figure. The 

 position of their feathers, tending backwards, and regu- 

 larly lying over each other, produces warmth, celerity of 

 motion, and security. Next to their skin is a soft down 

 to protect them from the cold ; while the exterior plumage 

 is arrayed in double beards, disposed and inserted in 

 the most perfect and regular lines, such as no ingenuity 

 of man can imitate. To secure them from the injury of 

 violent attrition or wet, birds are furnished with glands, 

 near the rump, distilling a kind of oil, which they occa- 

 sionally press out with their bills, and spread over the 

 ruffled feathers. This fluid, which is peculiar to the 

 winged tribes, varies in quantity, according to their 

 habitudes and necessities. Aquatic fowls possess it in the 

 greatest abundance ; and, though it improves their 

 plumage, it communicates a rank flavour to the flesh, 

 which renders some species disagreeable, and others 

 wholly unfit for our food. 



The position of the wings in every kind of birds is such 

 as appears best calculated to preserve the equipoise of 

 the body ; and at their extremities they have a finger- 

 like appendage, usually denominated the bastard-wing. 

 This auxiliary instrument of flight is likewise furnished 

 with feathers, which differ from the common only in the 

 largeness of their size, and their springing from the 

 deeper part of the skin. By its means, progressive motion 

 is facilitated, and strength communicated. 



To enter into the anatomy of birds forms no part of my 

 present plan ; yet I may properly notice a few particulars, 

 as likely to stimulate enquiry, and to evince how well 

 every creature is adapted to its sphere of action. The 

 eyes of birds, for instance, are more flat and depressed 

 than those of quadrupeds, by which means they are en- 

 abled to take in a wider expanse of vision. At the same 

 time, to guard the organ of sight the better from external 

 injuries, it is provided with a nictitating membrane, which 



