DR. PETTIGREW ON THE MECHANISM OF FLIGHT. 203 





Lifting -capacity of Birds. — The muscular power in birds is usually greatly in excess, 

 particularly in birds of prey, as e. g. the Condors, Eagles, Hawks, and Owls. The Eagles 

 are remarkable in this respect, — these having been known to carry off young deer, lambs, 

 rabbits, hares, and, it is averred, even young children. Many of the fishing birds, as the 

 Pelicans and Herons, can likewise carry considerable loads of iish* ; and even 1 be smaller 

 birds, as the records of spring will show, are capable of transporting comparativ. ly larg<- 

 twigs for building-purposes. I myself have seen an Owl, which weighed a little over 

 10 ounces, lift 2± ounces, or a quarter of its own weight, without effort alter baring lasted 

 twenty-four hours ; and a friend informs me that, a short time ago, a splendid Osprey was 

 shot at Littlehampton, on the coast of Sussex, with a fish 5 lbs. weight in its mouth. 



Conclusion.— There are many points in the history and economy of birds which erave 

 our sympathy while they elicit our admiration. Their indubitable courage and miraeulous 

 powers of flight invest them with a superior dignity, and secure for their order almost 

 a duality of existence. The Swallow, tiny and inconsiderable as it may appear, can I rttHsrse 

 1000 miles at a single journey ; and the Albatros, despising compass and landmark, tru^t 

 himself boldly for weeks together to the mercy or fury of the mighty ocean. rm - ■■- 

 Condor of the Andes, lifts himself by his sovereign will, to a height where no sound i 

 heard, save the airy tread of his vast pinions, and, from an unseen point, surreys in 

 solitary grandeur the wide range of plain and pasture-land t ; while the Bald Eagle, 

 nothing daunted by the din and indescribable confusion of the queen of waterfalls, the 

 stupendous Niagara, sits composedly on his giddy perch, until inclination or desire 

 prompts him to plunge into or soar above the drenching mists which, shapeless and 

 ubiquitous, perpetually rise from the hissing waters of the nether cauldron. 



The ™ 



RESUME. 



In taking a survey of the various topics touched upon in the course of my observa- 

 tions, I find they may be tabulated as follows :-- rtAanrfeoe 



I. In land Jmals, the bodies are heavy, and the feet comparatively 11, t I £ 



trod upon giving the requisite degree of support and resistance, "**^^£2 

 impediment in L way of displacement. The feet of the Horse, Deer, and Ox fu.msl, 



exampl 



supplied in many cases with membranes, which assumlate them l 



paddies, the flatLed surfaces of the feet being <*■-**££ t££ this 



the plane of greatest and least resistance, by a part al ^™ ^ cith( , r „,, 



result being likewise obtained by the opening and closing ol _ ^^ ^^ and 

 the feet act as inclined planes, progression being secured ity • ^.^ 



diminution of the angle in the plane of progression. The Sea , 



with it, o, pursuing a spiral, slightly oblique, oblique, .„ J 



* ' — i j G» i. 



even a transverse direction. ■ . , stents of his crop in order to reduce 



♦ The Heron is in the habit, when pursued by the Falcon, of d.sgorg.ng the contents 



liis weight. 



t The Condor, on some occasions, attains an altitude of six miles. 2 n2 



