290 THE HARMONIES OF NATURE. 



the limits of perpetual snow : like the lammergeier of the Alps, 

 he roosts on pinnacles where even in summer nights the ther- 

 mometer sinks many degrees below the freezing-point of water ; 

 but under their feathery mantle, these birds of prey feel not 

 the cold. Even in the tropical forests the temperature of the 

 air falls considerably after sunset, and then the parrot and the 

 toucan, the tangara and the cotinga, enjoy the benefit of a 

 vesture which prevents the heat of their bodies from radiating 

 into the cold atmosphere. 



To brave therigours of theNorth,theeider-ducks are furnished, 

 under their external cover of feathers, with a soft cushion of 

 down, which serves them also to line their nest, and in many 

 birds a lighter summer plumage alternates with a warmer winter 

 covering. 



As but few birds sleep under cover, and many of them are 

 exposed to every weather, they necessarily require a waterproof 

 mantle. For this purpose they have been provided with a gland 

 at the rump, from which they express an oily matter, which 

 spread over the plumage renders it impermeable to the wet. 

 The lubricating of their feathers with this unctuous fluid is one 

 of the chief occupations of many birds, particularly of the water- 

 fowl, in whom the gland by which it is secreted is, as might be 

 expected, particularly large, while it is totally wanting in the 

 ostrich, who in his arid home does not require its aid. 



Admirable as a most appropriate vestment, the feathers of 

 birds are scarcely less so from the splendour of their hues or the 

 elegance of their arrangement. What an astonishing variety of 

 shape and colour ! The plumage of the colibri rivals the 

 sapphire and the ruby in brilliancy. Which robe is most 

 pleasing to the eye, that of the snow-white swan, or that of 

 the scarlet macaw ? And who has the richest raiment, the 

 bird of paradise of New Guinea, or the mandarin-duck of 

 the Chinese lakes ? Can anything surpass the beauty of the 

 menura's tail, the diadem of the tody, or the gorgeous train 

 of the peacock ? Among such a host of competitors, it is diffi- 

 cult indeed to award the prize, or to select a prime favourite 

 among so many forms of beauty. 



An examination of the legs of birds opens new wonders to our 

 view, for here also we see masterpieces of adaptation of means 

 to end. Thus in the ostriches and cassowaries who, unable 



