Curiosities Of science.
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Tie following article is well worth
the attention of our readers; it is
part of an address by Prof. Mapes
before the Mechanical Institute of
New York:


mention these facts only in the
hope of showing you, that there is
pleasure in studying the sciences,
and when we come to Natural His
tory, we shall find the study Of that
still more amusing.-The animal and
vegetable world are well worthy Of
observation. Probably YOU all know
what is meant by cyciOd. If we
make a spot on the periphery Of a
wheel travelling on a plane, the fig
ure which the spot describes is cy-
clod. Now there is 10 figure in
which body can be moved with SO
much velocity, and with such regu-
larity of speed, not even the straight
line. Malhematicians discovered
this not many years ago; but ma.
ture's God invented ii. When tie
eagle pounces upon his prey, he de-
scribes thc figure of cyclod.


A globe, placed in water, or air,
in moving meets with resistance,
and its velocity will be retarded.
If you alter the globe to the form Of
an egg, there will be less resistance.
And then there is form called the
solid of least resistance, which math-
ematicians studied for many years
to discover; and when they had dis
covered it, they found they had the
form of Gsh's head. Nature had
'rigged OUT the fish into just such a
figure.


The feathers of birds, and each
particular part of them, are arrang-
ed in such an angle as to be most
efficient in assisting fight. The hu-
man eye has a mirror on which OBJ
jects are reflected, and nerve by
which these rene ctions are convey.
ed to the brain, and thus we are en-
abled to take an interest in the oh.
jects which pass before the eye
For, when the eye is too convex
we use one kind Of glasses to cor.
! rect the fault and if it be not con,
vex enough, or if we wish to look al
objects at different distances, we
use glasses Of entirely another des.
cription.


But as birds cannot get spccta.
cles, Providence has given them 9
method of supplying the deficiency
They have they power Of contract
ing the eye, Of making it more con.
vex so as 10 see the specks whicl
float in the atmosphere, and catcl
them for food; and also Of tlatteninG
the eye, so as to see at great dis
tance, and observe whether any vul
ture or other enemy is threatening
to destroy them.-They also have {
film, or coating, which can be sud
denly thrown down over the eye t
pretect it; because at the velocity
with which they fly, and with tn,
delicate texture of their eye, tn,
least speck of dust would act upo,
it as a penknife thrust into the hui
man eye. The film is to protect tn,
eye, and the same thing exists tC
some extent, in the eye of the horse
The horse has very la,ge eye, very
liable to take dust. This coating il
the horses eye is called the haw, O.
third cyelid, and if You watch close
ly, you may see it descend and re
turn with electric velocity, 1t clear
away thc dust, and protects the cy,
from injury. lfthe eye should catcl
cold, the haw hardens and projects
and ignorant persons cut it of, an,
thus destroy this safeguard.


You all know, if you take a poun,
of iron, and make of it rod foo
long, what weight it will support
make it hollow, and it will supper
a weight many times greater thar
before. Nature seems to have takcI
advantage of this also, long beior,
mathematicians had discovered it
and all the bones of animals are ho!
low. The bones Of birds are large
because they must be strong to NOV,
their large wings with sufficient vG
locity; but they must also be nght
in order to float easily upon Tie air
Birds also illustrate another fact il
natural philosophy. If you take
bag, make it air-tisht, and put it m
der water, it will support larg
weight, say an hundred pounds
But twist it, or diminish the air in il
and it will support no such weight
Now, bird has such an air bag
When he wishes to descend, he com
presses it at will, and falls rapidly
when he would rise, he increases il
and floats with ease. He also ha
the power Of forcing air into tn
hollow part Of his body, and thus t,
assist his fight. The same thin,


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