Andes—one of the largest of flying birds, having a wing- 
span of something over nine feet : 
“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 birds flap its wings. Near Lima, I watched several for 
nearly half an hour, without once taking off my eyes; they 
moved in large curves, sweeping in circles, descending and 
ascending without giving a single flap. As they glided close 
over my head, I intently watched, from an oblique position, 
the outlines of the separate 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 distinctly against 
the blue sky. The head and neck were moved frequently, 
and, apparently, with force, and the extended wings seemed 
to form the fulcrum on which the movements of the neck, 
body, and the tail acted. If the bird wished to descend, the 
wings for a moment collapsed; and then 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 soaring, 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 
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