Southwest-sentinel. [volume] (Silver City, N.M.) 1883-189?, 1895-10-29

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their movement is quito ipdepen-
dent Of any other horizontal cur
rent that theaif may have as relates
to the earth at the same time.
These currents may be going on
IN a valley surrounded by noun
tains without any other action Of
the atmosphere. On a plain, how
ever, there IS aso another action
taking place az the same time, but
which does not ID the least inter-
fere withathe vertical action, that
is, the whole body Of air may be
passing along over the surface Of
the earth at the rate, we will say,
of ten miles an hour, while the
vertical action is going on at a We
locity of, say four miles an hour.
The soaring Of a bird may be.
compared with a boy sliding down
hill on a sled. II a hill is, say,
100 feet high, and the sides slope
off ina horizontal direction 1900.
feet from the summit, and if the
snow is smooth, a boy can mount
a sled and advance 1000 eetwhile
he is falling, as gelates to the
earth. 100 feet; chat is, the. sled.
with the boy on it in falling
through a distance Of one footd de-
velopes sufficient power to drive
the sled forward 30 feet, but when.
the boy is at the bottom of the hill
and can develop no more power
by falling, the sled comes to a
state az rest. Suppose now that
a hill could be made in such a
manner that it would constantly
rise at such a velocity that the
sled would never reach the bot
tom Of the HILL the boy would
then be able to slide forever, and
this is exsctly what occurs with a
bird. A bird places its wings in
such a positionothat, asiit falls in
the air say onefo6t, it moves for
ward through the air 20 feet, that
is, 1t slides alongo on the surface
of the air underneath its wings in
the same manner that the boy
slides down the Hill. Suppose
now that the velocity of the bird
should be about 80 miles an hour,
this would account for the whole
phenomenon Of soaring on an up
ward current Of only II miles an
hour. With an upward current Of
two miles an hour, the bird would
rise, as relates to the earth, one
half a mile an hour while actually
falling through the air at the rate
of II miles an hour.
There is nogdoubt that a bird
by some very delicate sense o.
feeling and touch, is able 70 ascer
tain whether it is falling or rising
in the air. In all probability the
numerous air cells which ar,
, found in the body OLA bird AR
, provided with delicate nerves
which operate in a similar name.
to those of the swim bladder of
fish, so that as the bird is moving
forward through the air it is abb
to take advantage Of a rising col
umn OF. air. As a whole we ma,
consider that the rising column
! of air would be half of the tota
. area of the earth's surface, 30 tina
: a soaring Bird would always hav
s a rising column Of air whiel
8 would serve as 2 support he
t ferring TO the eagles which l saw
t in the Pyrenees, Von one occasion
/, observed five of these birds abou
500 feet above the peak of
8 mountain and they were balancing
themselves in a stationary posi-
ton on an ascending column o
air produced by the wind blowing
over the peak, and seemed to b
as much at ease rs if they wer
roosting upon a tree. AS a shil
passes through the air, the air i
divided exactly in the same man
q ner as water would be, and as /
comes together again at the ster.
!, of the ship it produces an up
e ward current, and it is on this az
Q cending column of air that tn
albatross and the seagull find
e resting place and follow the shi
for days at a time without an
p apparent ezeftion; but wheneve
they find themselves in front of
IS ship or at one side where there
% no ascending column of air the
= have often to work their passag
10 very much as other birds do.
But all birds do not soar, Duck
Reese. partridges, and pheasan.