1056 The Problem of the Soaring Bird. [ November, 
years to the birds on the Gulf coast of South Florida, where the 
soaring varieties were found in abundance, fully intending to un- 
ravel the case before leaving it. The task was a hard one, and 
the final solution was found in a totally unexpected direction, 
The predominant feeling I have since experienced in regard to it 
is one of surprise—surprise that in this ceaselessly active age 
mechanical possibilities of the most important character could 
exist in the atmospheric spaces all about us, with many of the 
largest species of existing birds putting them in daily practice 
before our eyes, and we still remaining completely ignorant of 
them! I propose in this paper to present, first, a few of the most 
significant facts exhibited by the soaring birds; next, to offer an 
explanation of the phenomenon; and finally, to examine the 
bearing of what has been said on the problem of artificial air- 
navigation. 
I mean by a “soaring bird” one which habitually travels the 
air on motionless wings. All birds flap their pinions at times, 
and many of the smaller kinds, such as rooks, kestrels, crows and 
gulls can maintain flight on fixed wings when the conditions are 
favorable. But I would never think of observing them for les- 
sons in soaring. They are too light to average the inequalities 
in the air current, and there are frequently long intervals of active 
wings before the fixed conditions occur. The soaring varieties 
are at it all the time. The frigate birds live in the air night and 
day for a week at a time without touching a roost. Their con- 
geners, the buzzards, spend the day in the same style, The vari- 
ous cranes common to the coast often spend hours resting in the 
air, while the gannet is an admirable soaring bird with a heavy 
body and relatively small expanse of wings. 
When I speak of “ fixed” or “ motionless ” wings the meaning 
is that no muscular power is used to either overcome weight or 
air resistance. It is not meant that the pinions are absolutely 
rigid, like a board, for they are moved to accomplish change both 
in shape and position. But they do precisely resemble a board 
so far as the exertion of motive power is concerned. For instance, 
_ if abird floats in a wind of unvarying velocity over any fixed 
_ point on the earth, then if a board of the same shape and size 
and weight were put in its place, it would remain there just as the 
bird does, as long as the conditions were unchanged. If the bird 
y changed the shape or position of its surfaces so as to ver- 
