186 S. CRUZ, PATAGONIA. [chap. ix. 



proclaim throughout the district to the whole family cf carrion- 

 feeders, that their prey is at hand ? 



When the condors are wheeling- in a flock round and round 

 any spot, their flight is beautiful. Except when rising from the 

 ground, I do not recollect ever having seen one of these bird* 

 flap its wings. Near Lima, I watched several for nearly half an 

 hour, without once taking off my eyes : they moved in large 

 2urves, sweeping in circles, descending and ascending without 

 giving a single flap. As they glided close over my head, I in- 

 tently watched from an oblique position, the outlines of the sepa- 

 rate and great terminal feathers of each wing ; and these separate 

 feathers, if there had been the least vibratory movement, would 

 have appeared as if blended together ; but they were seen dis- 

 tinct against the blue sky. The head and neck were moved fre- 

 quently, and apparently with force ; and the extended wings 

 seemed to form the fulcrum on which the movements of the 

 neck, body, and tail acted. If the bird wished to descend, the 

 wings were for a moment collapsed ; and when again expanded 

 with an altered inclination, the momentum gained by the rapid 

 descent seemed to urge the bird upwards with the even and 

 steady movement of a paper kite. In the case of any bird soar- 

 ing^ its motion must be sufficiently rapid, so that the action of 

 the inclined surface of its body on the atmosphere may counter- 

 balance its gravity. The force to keep up the momentum of a 

 body moving in a horizontal plane in the air (in which there is 

 so little friction) cannot be great, and this force is all that is 

 wanted. The movement of the neck and body of the condor, we 

 must suppose, is sufficient for this. However this may be, it is 

 truly wonderful and beautiful to see so great a bird, hour after 

 hour, without any apparent exertion, wheeling and gliding over 

 mountain and river. 



April 29th. — From some high land we hailed with joy the 

 white summits of the Cordillera, as they were seen occasionally 

 peeping through their dusky envelope of clouds. During the 

 few succeeding days we continued to get on slowly, for we found 

 the river-course very tortuous, and strewed with immense frag- 

 ments of various ancient slaty rocks, and of granite. The plain 

 bordering the valley had here attained an elevation of aboul 



