NATURALISTS CABINET. 



Centre of gravity Preservation against water. 



The centre of gravity in birds is behind the 

 wings; and to counterbalance it, most of them 

 are obliged to thrust out their head and neck in 

 flying. This is particularly obvious in the flight 

 of ducks, geese, and several other kinds of water- 

 fowl, whose centre of gravity is farther back- 

 wards liian in the land birds. The long head 

 and neck of the heron, on the contrary, although 

 foWed up in flight, overbalance the rest of the 

 body; and therefore the long legs are extended, 

 in order to give the necessary counterpoise, and 

 to supply what is wanting from the shortness of 

 the tail. 



To prevent the plumage of these animals from 

 perpetually imbibing the moisture of the atmos- 

 phere, and absorbing so much wet, during rain, 

 as might impede their flight; the wise economy 

 of nature has furnished the rump with two 

 glands, in which a quantity of oil is constantly 

 secreting. This is occasionally pressed out by 

 means of the bill, and used for anointing the 

 feathers. The birds that share, as it w r ere, the 

 habitations of man, and live principally under 

 cover, do not require so great a supply of this 

 fluid as those that rove abroad, and reside in the 

 open element : but water-fowls are endowed with 

 such a quantity as sometimes communicates a 

 degree of rancidity to the taste of their flesh. 



The wings, legs, claws, and beaks of all birds 

 are excellently adapted to their various pursuits. 

 Birds of prey that must fly to a considerable dis- 



