The Power of Flight Possessed by Birds 8i 



If it be true that birds, when migrating, require a wind 

 that blows against them, it implies an extraordinary power 

 as well as continuance of muscular exertion. We see 

 how Nature completes her work when the intention is that 

 the animal shall rise buoyant and powerful in the air. 

 The whole texture of the frame is altered and made light, 

 in a manner consistent with strength. We see also how 

 the mechanism of the anterior extremity is changed, and 

 the muscles of the trunk altered directly. In the in- 

 genious attempts which have been made to devise wings 

 to enable men to fly in the air, it has rarely been taken into 

 account that the muscles of the most powerful arm are pro- 

 portionately slender and weak when compared with the 

 wing muscles of birds. 



Even if artificial wings sufficiently efficient could be 

 contrived, the arms would be too feeble to wield them, 

 considering also that there are no air-cells distributed 

 through the human body as in birds to diminish its specific 

 gravity by inflation. It may prove interesting to many 

 of my readers to give a few details respecting these muscles 

 of flight in birds, and we cannot follow a better guide 

 than the late M. Chabrier, who made the flight both of 

 birds and insects his particulai study for nearly half a 

 century, and published the result of his earlier observa- 

 tions in a considerable volume. 



' ' If each muscle of flight," says he, ' ' were to contract 

 individually and independently of the rest, it would only 

 put in motion the most movable parts of the body with 

 which it is specially connected ; there would be no reaction. 

 This assertion is true in all respects, as, for example, in 

 the depression of the wings during flight, the resistance or 

 the contraction of the middle pectorals and their congeners 

 is absolutely necessary, since without it the wings would 

 fall by their own weight, and the action of the great 

 pectorals would be useless. Besides, in the depression of 

 the wings, the fixed point of the middle pectorals, where 

 the respective tendons attach themselves to the humerus, 

 being removed, the sudden contraction of these pectorals 

 must necessarily facilitate the ascension of the trunk until 

 the humerus is stopped by the cessation of action in 



