ANNOTATIONS AND ADDITIONS. 4i 



atmospheric strata from ten to eighteen thousand (about 

 10600 to 19000 English) feet above the level of the sea. 

 Humming birds, which make summer excursions as far as 

 61 N. latitude on the north-west coast of America on the 

 one hand, and the Tierra del Fuego on the other, have been 

 seen by Von Tschudi (Fauna Peruana, Ornithol. p. 12) in 

 Puna as high as 13700 (14600 English) feet. There is a 

 pleasure in comparing the largest and the smallest of the 

 feathered inhabitants of the air. Of the Condors, the largest 

 individuals found in the chain of the Andes round Quito 

 measured, with extended wings, 14 (nearly 15 English) 

 feet, and the smallest 8 (8J English) feet. From these 

 dimensions, and from the visual angle at which the bird 

 often appeared vertically above our heads, we are enabled to 

 infer the enormous height to which the Condor soars when 

 the sky is serene. A visual angle of 4', for example, gives 

 a perpendicular height above the eye of 6876 (7330 English) 

 feet. The cave (Machay) of Antisana, which is opposite the 

 mountain of Chussulongo, and from whence we measured 

 the height of the soaring bird, is 14958 (15942 English) 

 feet above the surface of the Pacific. This would give the 

 absolute height attained by the Condor at fully 21834 

 (23270 English) feet; an elevation at which the barometer 

 would hardly reach 12 French inches, but which yet does 

 not surpass the highest summits of the Himalaya. It is a 

 remarkable physiological phenomenon, that the same bird, 

 which can fly round in circles for hours in regions of an 

 atmosphere so rarified, should sometimes suddenly descend, 

 as on the western declivity of the Yolcano of Pichincha, to 



