ORGANISATION OF BIRDS. 303 



of which they are susceptible, we are within the truth 

 when we say, that, counting from morning to night 

 every day for a thousand years, would be insufficient 

 simply to enumerate all the motions and positions, of 

 which even this joint of one wing of a single bird is 

 susceptible. 



Still, in order to be able to observe birds with ad- 

 vantage, as they appear to us in every-day nature, so 

 as to turn them to those purposes of instruction and 

 companionship to which they can so easily and 

 pleasantly be turned, it is necessary to have some 

 general notion of the parts of a wing. These parts, 

 considering them simply according to the substances 

 of which they are composed, are, first, feathers, which 

 being palpable to the eye without much, or even any 

 separation of parts, may be ranked among the mere 

 external appearances, as noticed in a former section ; 

 secondly, the substance of the solid wing which is 

 made up : these are the bones and muscles, of which 

 some notice has also been taken, but it may be ne- 

 cessary very briefly to revert to them. 



The jer-falcon, to which we have already alluded 

 as the most typical of birds in their general character 

 as flyers, may be again advantageously used as a 

 model, and the figure of the bones of its wing exa- 

 mined in comparison with the corresponding portions 

 of the human arm. The figure on the next page 

 represents the bones of the right wing in half the 

 lineal dimensions of nature. 



The position is nearly that of the closed wing ; and 

 it can be understood by bringing the elbow against 

 the side, the wrist to the shoulder, and bending down 

 the hand on the fore-arm. The portion marked a 

 answers to the humeral part of the human arm, that 

 is, from the shoulder to the elbow, and consists of a 



