The Yale expositor., 1913-10-16
Rapid Motion and Powerful
Vision Go Together.
Eagle Has Telescope Eyes-EVen the
Familiar Robin and the Jay Have
Been Sineularly Endowed by
Nature in This Respect.

Chicago.-The eye in the bird king
dom is telescope, with the fish it is
microscopic, in the mole rudimentary.
The eagle and the vulture have the
faculty of adjusting the eye to dis
Germ objects at great distance. The
eagle from the far off mountain sees
the flock in the valley below and ac-
curately surveys the situation for his
descent. AS he swoops nearer and
nearer to his victim the lens in his
eye steadily readjusts itself to the de-
creasing distance and when he strikes
the lamb already chosen for his dinner
the long distance vision has narrowed
down to the scope of few yards.
The vulture is equal TO the eagle in
vision as he is in flight. Every farmer
knows if he kills a blue racer and
leaves it by the roadside vulture
soaring overhead comes down and APP
propriates It, In South America,
where the condor lives, the hunter of
wild animals dares not leave his game
long exposed and unprotected At first
not condor can be seen, but present
ly dark speck appears in the upper
air and it grows larger and is soon fol-
lowed by another and another, until
score of condors have descended to
the feast These have the telescope
eye. From the height of mile or tvo
these birds survey the earth beneath
and observe the movements of all
creatures below. Mankind can equal
such vision only by artificial aid,
which is an application of the pro
cesses of nature. The eagle possessed
a telescope before Galileo's invention.
Any farmer boy who has ever at
tempted to come within gunshop of a
crow or a hawk perched on the dry
limb of a tree can testify to the sharp
vision of these birds at long distance.
Cookers hawk is the greatest enemy
to the poultry yard. Soaring high in
the air, this bird Of prey sees the tiny
chicks, and he comes like rocket TO
seize the one he has chosen as a tar
get Even the common birds about
the lawn-the robin and the jaybird-
have this same eaglelike power of
vision modified to their requirements.
The jaybird will detect very tiny
worm or insect in the grass from dis
lance Of forty or fifty feet and will de-
scend upon the object with unerring
aim of beak. The seed eaters, meadow
larks and sparrows. need no such vi
sion, and are therefore denied its pos
session.
The eye OF the owl is especially de-
signed for short distance vision. This
bird can see imperfectly but a few
yards away. The eye of the owl is ar
ranged to concentrate a great diverg-
ence of the rays of light whereby the
bird can discern near objects in a
faint light The owl can see very well
at short distance even in thick
darkness. The owls eye is somewhat
dishlike and fiat, so that much light
may enter. This arrangement per-
mits too much light to enter the pupil |
in the daytime, and therefore owls are
almost blind in the glare Of the sun.
There is a correlation between
swiftness of wing and range of vision.
The owl is exceedingly slow of mo-
swiftness of wing and range Of vision. |
vision, while the longer sighted ami |
mails are swift of foot Fleet animals.
such as the antelope and deer and
others living on boundless prairies,
can see a long distance and are swift |
in movement. Animals living in the |
woods have no need of such long |
vision nor swift movement All crea-
lures living in spacious regions and |
strong light move rapidly and with |
clear vision. as instance the fly catch
er, the king bird and the chimney |
swift, which take their food on the |
wing. The motions of these birds are
exceedingly graceful as well as rapid.
Their vision is both telescope and NIL
croscopic.
Whether birds have the power of
discriminating between different col |
ors is an open question. An old bee
keeper holds that the bee knows one |
color from the other, and he therefore /
paints the hives in various colors as /
guide to the weary. heavy laden work