The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1897-12-05
HON WIND Is MADE USE Of
IO AID BIRDS N FLIGHT.
A Problem Worked Out by Young Birds--Why
Gulls Can Follow Ship Without Seem
ing to Use Their Wings.

We see then that IL the lark wishes the
wind te help him 10 rise. nc must face IL
Incline the body forward as q kite IS an
ciined: and further that the inequality OF
the wind must give him inertia. or mo-
msurur. or else his wings will have 10
raise hirn without assistance. When guils
advances to right angles with the WIND
wirhou. any beating of the wings. the
principle applied Is the same From some
slight elevation they glide downward tai
they are near the ground or the surface
OF the sea, then tpossibly by a twist az
the waist they turn suddenly and face
the wind, which lifts them TO their former
elevation: after which the process begins
again L may be that when birds soar,
!. G.. rise in spirais without moving their
wings. they are awaiting themselves ct
each upward step Of the Increasing veioc
lily of the wind. But they sometimes at
tain an elevation of a mile or more. and
there the increase must be a negiibie
quantity. IL IL has not at length reached
the vanishing poins; and. therefore. we
have TO look elsewhere for an explanation
OF soaring.
This brings us to the subject of up-cur-
rents, obviously much TO be desired IL wing
labor is to be saved. and birds, whenever
such assistance is TO be had, are always
ready 10 profit by it. When the wind blows
against a cliff IL is. OF course. detected
upward. and gulls may sometimes be seen
enjoying the fun of being lifted like
foam bubble Of the up-eurrent, then de-
scendlng to be lifted again. Oftener they
may be seen soaring over cliffs or hills near
the shore. ascending in noble spirais with
out motion OF their wings. The secret
lies in the upward slant of the wind.
But soaring may be seen under quite diff
ferent circumstances. The adjutant bird
one OF the noblest of soarers, rises till he
looks mere speck or vaaisnes altogether,
over the plain OF Burmah. Can there be
up~eurreDts there? 1t Is possible that
owing 10 the ground being unequaliy heat
ed by the sun, there may be such currents
here and there. But in Egypt have seen
kites soaring over fields where the young
corn was growing thick and green. and
where. consequently. the earth's surface
was not much heated Probably the adj
jntant depends on the irreguiarity of the
wind
Even what we call steady wind. we
know, by Prof. Langleys experiments, is
very unsteady, and varies enormously in
velocity from one moment to another. This
fact the adjutant may make use OF, deriv-
Ing the indispensable inertia or momen-
tum. AS long as he can offer resistance
10 the breeze. not being carried by IL like
a balloon. but feeling 1t blowing In his face,
SD long the breeze will continue to lift
him Whenever the wind freshens he will
turn and face 1t and will rise like a kite.
When Il slaekens he viii sail with Il, de-
scendng slightly, Obviously, there will
be a good deal of leeway, a phenomenon
vonched for by good observers. but there
will be "A gain I'm altitude. And thus the
grand bird making even the wind. that
chartered libertine,' his slave. rises high
er and higher. often. no doubt. watches as
he scars for carrion on the earth below,
but often. probably, delighting only in the