102 BONES OF THE WINGS. 



adapted to each other with the utmost perfection, so 

 that it can rush onward in any line of direction that 

 it pleases, without the least deviation ; therefore it 

 flies from point to point by the shortest line possible ; 

 and thus while it is the perfect model of power in 

 flight, it is at the same time the perfect model of 

 economy. 



The lumbar portion of the jer-falcon's spine admits 

 of a little bending downwards, so that the articula- 

 tions of the femoral bones, or those joints which 

 answer to the hip joints in the mammalia, can be low- 

 ered a little. The bones of the tail are also more 

 numerous and better " made out" than in most birds. 

 This arrangement of the posterior portion of the 

 sternum, enables the falcon to perform more effec- 

 tively its double action in the air, as by this bending, 

 the foot, with which it strikes its prey, can act so far 

 below the plane of the wings as not to interfere 

 with their motion of flight. Not only this, but it also 

 affords a support to the tarsus, upon the joint of 

 which the whole force of the stroke would otherwise 

 be thrown as a cross-strain ; and, though that joint 

 is a firm one, yet it is contrary to the general law of 

 nature's mechanics, to subject even the firmest joint 

 to the greatest strain which it has to bear in the least 

 favourable position. Indeed, there is seldom any joint 

 subjected alone to a very great strain, in the natural 

 action of animals. As there is but one life in the 

 animal structure, so there is always concerted action 

 when that life is strongly excited, be the object of 

 the excitement or the organisation which it more 

 immediately sets at work, what it may. There is 

 some part upon which, in case of partial failure, the 

 acting part can fall back for support if not for assist- 

 ance ; and the very fact that organs which have to 



