1887. | NEW YORK ACADEMY OF SCIENCES. 83 
telephone, and telescope, had been the result of groping after 
Nature’s method. We had now come to the problem of aérial 
navigation, which was successfully accomplished by birds. It 
was the opinion of many that if man ever succeeded in this 
method of locomotion, it would be not by the balloon, but by 
some mechanical device in imitation of the flight of birds. 
Dr. J. B. HOLDER read the following notes on the 
SOARING OF BIRDS. 
It is a matter of record that several notable scientific ex- 
plorers, especially those who examined the fauna of South 
America during the first half of the present century, were at- 
tracted to the extraordinary evolutions and great apparent 
buoyancy of the large soaring birds of the region. But, fora 
long time, so far as we have been able to determine, attempts 
to explain clearly the phenomena of soaring, in its several 
phases, have been abandoned. Of late, considerable attention 
has been given to the theme, and several observers have ap- 
proached what seems to be the true theory. 
It is our purpose here to place on record some interesting 
data which will help the solution of this problem. 
During the winter of 1858, while serving as medical officer 
at Fort Jefferson, Tortugas, on the Florida Reef, and when 
garrison duties allowed abundant time for observing the novel 
and interesting objects of that semi-tropical region, one of the 
first attractive circumstances was the apparently constant so- 
journ of the frigate pelican (Tachypetes aquila)—called there 
the ‘‘man-o’-war bird ”—or ‘‘ hawk.” 
There were many of these birds, and during the winter 
months they hovered over the fortress during the day, and 
roosted at night on the dwarf cedars of the neighboring 
keys. 
Their wonderful poise and admirable faculty of soaring 
soon became a theme for continued observation, particularly as 
a lighthouse tower within the fortress afforded extended oppor- 
tunities for view. 
With a position in the lantern of the tower, and a good field 
glass, one was both concealed and brought into proximity to 
the birds, wholly satisfactory for purposes of observation. 
Some mention of the soaring of birds by Humboldt, who ob- 
served the flight of the condor in its beautiful evolutions, and 
similar notices by Charles Darwin in his ‘‘ Voyage of the Beagle,” 
suggested a careful series of observations, and close scrutiny of 
this, the most notable flyer, in its chosen home. 
