198 THE STRUCTURE AND LIFE OF BIRDS chap. 



slower and stronger strokes, the rate of movement of 

 the further end of the wing increasing enormously with 

 increase of length, and the resistance of the air in- 

 creasing out of all proportion to the increase of 

 velocity. Thus, in proportion to his weight and bulk, 

 a big bird will require a firmer pivot for his wing than 

 a small one. But the comparatively small inter-cora- 

 coidal angle in the Pheasant (if I have estimated it 

 correctly) shows that power of flight as well as size 

 must be taken into consideration. 



The working of the passive machinery may be seen 

 well in a dead bird. Only extend the arm, and the 

 hand is extended ! Only extend the hand, and all the 

 large feathers are spread ! The radius, as I have 

 explained, slides back when the forearm is extended 

 and pulls the hand with it, bringing it into line with 

 the arm. Then follows the sudden expansion of the 

 wing feathers like a fan, effected by means of elastic 

 ligaments through which the primary and secondary 

 feathers pass, and which are stretched directly the 

 anele between the hand and forearm is widened. The 

 system of ligaments is elaborate. If the skin is removed 

 it will be seen that each of the great feathers is fastened 

 to the bone by a stringy tendinous mass. Even in 

 the dry skeleton they leave their mark. The elastic 

 ligaments can be made out without any dissection. 

 One, through which the quill of each feather passes, 

 can be clearly seen extending from the extremity of 

 the handbone or metacarpal to the armpit, including, 

 therefore, all the secondaries, and, with the exception 

 of those that spring from the fingers, all the primaries. 

 It is in fact a continuation of a tendon connected with 



