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KIDD'S LONDON JOURNAL. 



avoid those enemies which they are not 

 fitted to oppose, they are endowed with the 

 faculty of ascending into the air. They ap- 

 pear, indeed, to be entirely formed for a life 

 of escape, every part of their anatomy being- 

 calculated for swiftness ; and, as they are 

 designed to soar on high, all their parts are 

 proportionably light. This leads us to con- 

 sider more particularly the structure of 

 birds. 



The skeleton or bony frame of birds is, in 

 general, of a lighter nature than in quadru- 

 peds ; the spine is immoveable, but the neck 

 lengthened and flexible : the breast-bone 

 very large, with a prominent keel clown the 

 middle, and formed for the attachment of 

 very strong muscles. The bones of the 

 wings are similar to those of the fore legs 

 in quadrupeds, but the termination is in 

 three joints or fingers only ; of which the 

 exterior one is very short. What are com- 

 monly called the legs, are analogous to the 

 hind legs in quadrupeds, and they terminate 

 in general in four toes, three of which are 

 commonly directed forwards, and one back- 

 wards ; but in some birds there are only 

 two toes, in others, only three. All the 

 bones in birds are much lighter, or with a 

 larger cavity, than in quadrupeds. 



The feathers with which birds are covered, 

 resemble in their nature the hair of quadru- 

 peds, being composed of a similar substance 

 appearing in a different form. " Every single 

 feather," says Paley, "is a mechanical wonder. 

 If Ave look at the quill, we find properties 

 not easily brought together, — strength and 

 lightness. I know few things more remark- 

 able than the strength and lightness of the 

 very pen with which I am now writing. If 

 we cast our eye toward the upper part of 

 the stem, we see a material made for the 

 purpose, used in no other class of animals, 

 and in no other part of birds; tough, light, 

 pliant, -"elafeti'c'. 1 'The pith, ; also, which feeds 

 the feathers, is neither bone, flesh, mem- 

 brane, nor tendon. 



" But the most artificial part of a feather 

 is the beard, or, as it is sometimes called, 

 the vane ; which we usually strip off from 

 one side, or both, when we make a pen. 

 The separate pieces of which this is com- 

 posed are called threads, filaments, or rays. 

 Now the first thing which an attentive ob- 

 server will remark is, how much stronger 

 the beard of the feather shows itself to be 

 when pressed in a direction perpendicular 

 to its plane, than when rubbed either up or 

 down the line of the stem ; and he will soon 

 discover, that the threads of which these 

 beards are composed are flat, and placed 

 with their flat sides towards each other ; by 

 which means, while they easily bend for the 

 approaching of each other, as any one may 

 perceive by drawing his finger ever so 



lightly upwards, they are much harder 

 to bend out of their plane, which is the 

 direction in which they have to encounter 

 the impulse and pressure of the air, and in 

 which their strength is wanted. It is also 

 to be observed, that when two threads, 

 separated by accident or force, are brought 

 together again, they immediately reclasp. 

 Draw your finger down the feather, which is 

 against the grain, and you break, probably, 

 the junction of some of the contiguous 

 threads ; draw your ringer up the feather, 

 and you restore all things to their former 

 state. 



" It is no common mechanism'by which 

 this contrivance is effected. The threads 

 or laminae above mentioned are interlaced 

 with one another ; and the interlacing is 

 performed by means of a vast number of 

 fibres or teeth which the threads shoot forth 

 on each side, and which hook and grapple 

 together. 



" Fifty of these fibres have been counted 

 in one-twentieth of an inch. They are 

 crooked, but curved after a different man- 

 ner; for those which proceed from the 

 thread on the side toward the extremity of 

 the feather are longer, more flexible, and 

 bent downward ; whereas those which pro- 

 ceed from the side toward the beginning or 

 quill-end of the feather, are shorter, firmer, 

 and turned upward. When two lamina?, 

 therefore, are pressed together, the crooked 

 parts of the long fibres fall into the cavity 

 made by the crooked parts of the others ; 

 just as the latch which is fastened to a door 

 enters into the cavity of the catch fixed to 

 the door-post, and there hooking itself, 

 fastens the door ! " 



Beneath, or under the common feathers or 

 general plumage, the skin in birds is imme- 

 diately covered with a much finer or softer 

 feathery substance, called down. The throaty 

 after passing down to a certain distance, 

 dilates itself into a large membraceous bag, 

 answering to the stomach in quadrupeds ; it 

 is called the crop, and its great use is to 

 soften the food taken into it in order to pre- 

 pare it for passing into another strong re- 

 ceptacle, called the gizzard. This, which 

 may be considered as a more powerful sto- 

 mach, consists of two very strong muscles, 

 lined and covered with a strong tendinous 

 coat, and furrowed on the inside.* In this 

 receptacle the food is completely ground and 

 reduced to a pulp. The lungs of birds differ 

 from those of quadrupeds in not being 

 loose or free in the breast, but fixed to the 

 bones all the way down : — they consist of a 

 pair of large spongy bodies, covered with 



* In the birds of prey, or accipitres, this is wanting 1 , 

 the stomach being allied to that of quadrupeds. 



