RECORDS OF MOVEMENTS FROM OBSERVATION. 
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.” 
The writer has frequently, while crossing the Atlantic, 
carefully watched with a powerful binocular glass, the 
motion of gulls while soaring quite close to and around 
261 
the stern of a steamer, but notwithstanding the failure of 
his efforts, and those of others, to detect any motion in 
the primary feathers of the wings, he ventures the opinion 
that the power possessed by a bird of causing them to 
make a partial revolution, independently of any action 
of the wing itself, must be considered as a necessary factor 
in a solution of the problem of soaring. 
