302 ORGANISATION OF BIRDS. 



merely the numbers, lengths, and arrangements of the 

 flying feathers, which are almost the only characters 

 usually noticed even by those who profess to write 

 scientifically upon this class of animals, are highly 

 important toward the formation of such a systematic 

 arrangement as shall be of use that is, which shall 

 direct and shorten the labour of the student who seeks 

 for a knowledge of the characters and uses of these 

 highly interesting creatures. 



The mass of the body in birds is, from the inflexi- 

 bility of the spine, what may be called passive, or 

 rather consenting, in those actions wherein the cha- 

 racters of birds are displayed, as it does not directly 

 perform any of those external operations which are 

 open to observation, though there is no doubt that it 

 is always of that form which gives greatest facility to 

 the more active part of the animal, whether that part 

 be bill, or foot, or wing. To enter minutely into the 

 anatomical structure of a wing, so as to make all its 

 parts intelligible to common readers, would require 

 far more space, and more illustration, than are com- 

 patible with the nature and design of this work ; and 

 without a perfect knowledge of the parts, it would of 

 course be impossible to give any idea of their indi- 

 vidual action. Then, as to the joint-action of the 

 whole, that is a matter which cannot be expressed. 

 There are twelve distinct moving forces all acting, in 

 one way or other, upon the first, or shoulder-joint of 

 the \\ing. Those forces are all different in what may 

 be called their structural energy in the power they 

 derive from their manner of application in their effect 

 in different positions of the wing and in their energy 

 from different degrees of excitement in the bird ; so 

 that, when we take those causes of difference, and 

 consider them in all the combinations and changes 



