4 cassell's book of birds. 



provision is therefore met with in the Feathers with which all birds are so warmly clad. Indeed, 

 so peculiar is the texture of these admirable fabrics, that no better distinctive appellation could 

 be devised for the entire class than that of the " feathered tribes," by which they are frequently 

 designated. A feather realises in its structure more qualities than imagination could have conceived 

 it possible to combine — lightness, thickness, warmth, durability, elasticity, softness, strength, and 

 beauty. It is one of the master-works of creation. Whoever has examined a feather under the 

 microscope will testify to the incomparable perfection of the contrivance. Every feather is a 

 mechanical wonder. If we look at the quill-portion, or barrel, we find it possessed of attributes not 

 easily brought together — strength and lightness. If we cast our eye upon the upper part of the stem, 

 we see a material made for the purpose, which is used in no other class of animals, and in no other 



Fig. 2. — WING OF A BIRD PARTIALLY STRIPPED OF FEATHERS, TO SHOW THE INSERTIONS OF THE QUILLS. 



a, the Arm ; d, the Fore-arm ; g, the Thumb ; c, the Secondary Quills, implanted into the Fore-arm : f, the Primary Quills, implanted into that 

 portion of the Wing which represents the hand ; e, the Spurious or Bastard Quills, derived from the Thumb. 



part of birds — tough, light, pliant, elastic — the pith. This is also a substance sui generis ; it is 

 neither bone, flesh, membrane, nor horn. 



But the most wonderfully constructed part of a feather is the pht7iie, or, as it is sometimes called, 

 the web. This is affixed to each side of the stem, and constitutes the broad expansion of the feather, 

 that part which we usually strip off when making a pen. One of the first things to be remarked is 

 that the web is much stronger when pressed in a direction perpendicular to the flat plane of the 

 plume than when rubbed either up or down in the direction of the stem ; the reason of this is that 

 the web is composed of numerous flat, thin, and broad laminae, arranged with their flat sides 

 together, so that, although they easily bend towards each other, they offer great resistance in the 

 direction in which they have to encounter the impulse and pressure of the air ; and it is in this 

 direction only that their strength is wanted and put to the test. 



Another particularity is still more admirable. Whoever examines a feather cannot help noticing 

 that the laminae of which we have been speaking, in their natural state seem to be fastened together. 

 Their adhesion to each other is manifestly something more than mere apposition ; they are not to be 

 separated without a certain degree of force, and, as there is evidently no glutinous cohesion between them, 



