Evening star., 1896-12-02

believe. the same below the surface of the
earth as 1t is above. 1t argues that the at
earth's center. and, therefore, would in
crease In the same proportion below the
surface as 1t increases above. The attrac-
uon OF gravity, II any. between the earth's
ed for In this formula.
In the foregoing I have endeavored to
snow that a hundred-pound iron ball, If
dropped into hole extending through the
eafths center, would, whether in air or
vacuum. finally rest at the center Also
that the ball would not revolve with the
earth II In vacuum. and, further, that
the ball would be displaced II another ball
was dropped In, and would continue to be
displaced until 1t finally reached the op-
Pcsite surface of the earth. provided enough
balls were dropped In to fill the hole.
nave also stated my reasons for thinking
SUCH
The Pendulum Movement.
Thomas Hoge writes: II have been inter-
ested in the various answers given in The
Star to the question Of what a 1OO-pound
Dali would do or where 1t would go II
dropped into hole extending straight
through the center Of the earth, coinciding
with diameter of the earth.
Il fully agree with the conclusions set
out In the 'broadside answer Of S. s. K in
Saturdays Star. and 1 am not sure that
l could make tie thing any clearer than
goes into the question. But there are some
other very Interesting features or require
ments not touched upon, SO far as l have
read the answers.
II think the best illustration We have
Of very similar movement is in the COM
mon pendulum. If we turn the pendulum
rod up to one side until 1t extends out
level from the pivoted point, then 1t takes
the greatest force. the full weight Of the
ball. to hold it there. So the greatest
weight of the other ball is at the surface
of the earth. When the pendulum las
descended part way from that 1t takes
less force to hold 1t in that position. be-
cause the pendulum rod partly balances
the force of gravity by pulling against it
in an angular direction. and the further
the bali descends the less that ang llar di
rection, until the ball comes directly under
the point of suspension. where the pen
dulum rod, pulling in direct line with gray
ity, but in the opposite rection, wholly
balances gravity. and the ball remains at
rest If placed there without motion or mo-
mentum in 1t. Likewise a hall passing
into a hole through the earth has less and
less apparent weight until it reaches the
center. where it has no weight, because the
force of gravity upon it being equal In all
directions Is balanced in all directions
and the ball remains at rest there, If placed
there without motion or momentum WITHIN
itself to carry 1t away from there.
Now. when a ball falls into hole ex-
tending through the earths center, the
weight of the ball gets less and less until
1t reaches the center. where it is nothing.
as a pendulum hanging directly under the
point CT suspension. But when we pull
pendulum ball out level with its point OF
suspension and let it 60 does it stop when
1t gets down to the lowest point because it
has no tendency to swing from that point?
No, we all know that while the force during
its descent is getting less and less, till
nothing al the lowest point. 1t does not
stop at that point. but just there it has at
tanned its greatest speed and therefore
t<.,t &hot
tum will carry 1t just as far beyond that
point as from that point to the starting
point. less loss by friction and resistance
OF the air. Just SO the ball dropped into
the hole through the earth will have at
tained its greatest speed at the center of
the earth. but its inertia does not permit
1t to stop there. but carries it just as far
beyond that point the distance back 20
the starting point, which will take 1t 20
the other end Of the hole from which it
will fall back and reverse the course and
continue to oscillate perpetually. provided
the other necessary conditions are main
tanned.
Now let me ask query in this connec-
ton whose correct solution will prove very
curious and very interesting. Suppose we
start our hole at Buenos Ayres South
An erica. and go straight through the CEN
ter of the earth. 1t will come out on the
east coast of China. near Marking. Now
suppose we drop the ball into the hole al
Buenos Ayres on Sunday at noon. and sun
pose it takes the ball five hours TO reach
CHINA What day of the week will it be in
CHINA when the ball Its there? And sup
pose the ball starts ! ,ck immedia tely and
tEat 1t takes 1t anot er five hours to reach
BIenos Ayres. What day of the week will
i be at Buenos Ayres when the ball gets
back there?" e>'
The Earth a Shell.
The following is contributed by r. E. A.:
" nile the ball and earth discussion Is
being prosecuted with such vigor and so
many able explanations are being ad-
vanced it is but proper that another an
parent solution be made known So far
as have been able to see the contributors
nave ignored the suppositfon that the earth
IS Shell, composed of a dense hard ex-
terror with, possibly, a liquid and gaseo1s
nnlhe, nm respectively, 6eneath). Looking at
the matter from this new standpoint We
nave, l think, changed the conditions ma
terially. AS gravitation is the attraction
which every particle of matter has for
every other particle. wherever located, we
nave IN the sravitation of the earth nu-
merouS lines of force emanating from every
portion Of the shell.
Now, with this as a starting point, we
Will suppose hole devoid of atmosphere
"a gaseous resistance would cause a ball TO
be vaporizeD and The ball dropped therein
and depending solely upon gravitation and
centrifugal force. AS the ball left the
surface the resultant of the gravitation
forces being stronger than the centrifugal
force would rapidly draw it down with ac-
CELEBRATED speed until a large portion of the
earth's crust had been passed, when a
perceptible counter gravitation force would
begin to act and increase until the attrac-
tion toward the center of the earth would
be balanced by the combined forces Of
gravitation from without plus the centri-
fugal force This would retard the ball
but not sufficiently to prevent it's momen-
tum carrying it across the line of balance
through or across which 1t would vibrate
Indefinitely.
1T may be suggested that the earth has
two. sides, each exerting an equal force.
but this would be true only where the OBJ
ject acted upon is in the center. Accord
ing to the laws of attraction the forces
exerted by each side respectively would
be inversely as the square of its distance
fro m the ball, SO that that of the distant
side would be comparatively infinitesimal
when thin shell and large sphere are
cor rsidered In conclusion would say that
If the hole were made at the poles and
thus exclude the centrifugal force the ball
would simply sink lower until 1t arrived
in the region of balanced gravitation at
fractions which would probably be at or
about the inner surface of the earth's
crust"
RObberfes Reported.
Timepieces seem to be the principal at
traction for thieves just at present. A
lady's gold hunting-case watch, with cross