Evening star., 1896-12-02
THE EARTH'S CENTER
More About What Would Happen to a Ball
Dropped There.
Views Of Several Contributors to The
Star ON This Subject-ScOpe
of the Discussion.

Views In regard to the conditions sur
rounding an iron ball in the center Of the
earth continue to be expressed by cor
respondents of The Star. The discussion
is continued by the following:
r. r. H. writes: while that hundred
pound iron ball is oscillating from one
critic to another l would like to state my
views on the subject. with the possible
chant of bringing the ball at rest little
nearer the earths center than some of my
colleagues seem willing to have it."
E. l.. F.. in Fridays Star, expressed him
self as quite amused at the conclusions of
Mr.. Lightbourn that the ball would finally
rest at the earths center until crowded out
by heavier mass. and seems to think he
has dealt a knockout blow" when he
asks Mr.. Lighthourn to state which would
be the heavier mass at the earth's center,
IAN iron balI ball of yarn"
Il may Re able to afford E l.. F. fur
ther amusement by stating that the ball
most Influenced by the attraction of graT-
ity would be the heavier. By this / mean
ball containing enough yarn to be at
tracted by gravity to the extent of 100
pounds would at the earth's center weigh
twice as much as a bail containing enough
iron to be attracted by gravity to the ex-
tent of lUh pounds. and vice versa
Therefore mass of 2n pounds would
throw mass of 100 pounds just one-half
of the combined weight of the mass off
center. i.e., l5n pounds would rest on either
side of the earth's CENTER .a
This can be illustrated by taking three
perfect spheres the balls from the bear
ings of a bicycle will answer) and placing
ore OF them in glass tube bent in half
circle with the ends projecting a little be-
yond the center of the circle, after the
fashion Of horse shoe. The ball will rest
at the lowest point OF the semi-c.rcle,
which H.. of course the center of gravity
and rpDTeSpntS the farth'S
the other two balls are dropped in it
will be found the middle one occupies tn.
lowest point. which throws one and one
half ball or one-half the entire mass on
either side of the center of gravity.
Il notice that several who have seen fit
to argue this subject treat the weight of
the ball and the attraction of gravity as
two distinct elements while | have always
understood and believed the two to be one
and the same that is, the influence of the
attraction of gravity on different bodies is
measured In pounds. Hence a piece of iron
might be said to lose it's weight when sub
1ected to the influence Of magnetism to the
same degree as that Of gravitation or any
other substance loses its weight when an
other power is brought to bear on it in
equal proportion to that of gravity.
The next correspondent asks, But
would the ball rest when it reached the
earths center? and then, without giving
any one else a chance to answer, SAYS As
suredly not He would have done well
Aieid he SioScu argument with this very
positive answer, but he goes on to state the
ball becomes the center of the earth's axis
and revolves from west to east once every
twenty-four hours. in perfect harmony with
the diurnal motion of the earth. Accord
ing to this argument the motion of the hall
In relation to the earth is about the same
as that Of the Capitol building, which is
generally conceded to be stationary, not
w1thstanding it., too. makes a complete
revolution (of the earth's circumference,
once every twenty-four hours
10 my thinking the ball would appar-
entiy revoive In just the opposite direction,
that is, from east to west, due to the fact
of the ball being stationary while the earth
fevolVed around 1t from west to east. In
asmuch as the ball is supposed to be in a
perfect vacuum, and held suspended by the
attr3ction of gravity, which is equal at
every point, l see no reason why the ha III
should move.
If air is admitted to the hole, then it is
reasonable to suppose the friction against
the earth would set the air in motion, and
this III turn would impart to the ball the
same motion of the earth. But under these
conditions the ball would be said to be
stationary, meaning. of course, in relation
to the earth.
The llext correspondent scores some very
good points, but makes very poor finish.
think. when he says the ball would in
vacuum, when started from one side of the
earth, continue to the opposite side and
then return to the starting point and con-
eiiAoS w sAoA"tC fAdehillGly. IL lIlS were
So the attraction of gravity would cease at
the earth's surface. and should the ball
chance to get little beyond the surface it
would. like the Wandering Jew, keep NOV
ever. that the vibrations would become
shorter and shorter If air Is admitted, and
that the ball would finally rest at the
earth's center. 1t is surprising to me that
many OF those writing on this subject re-
cite at length the laws of natural physics
to substantiate their views and then con-
ciude the ball would have perpetual motion
"a theory In direct contradiction to natural
physics.
Some make this mistake by treating the
weight of the ball and the attraction of
gravity as two distinct powers, and claim
the weight would give Sufficient momen-
the earth t. carry it to the opposite sur
face. Now, for the sake of argument, sup
pose momentum to be power sufficient to
carry the ball to the surface of the earth,
would cease at exactly the same distancs
from the earth's center as therearths CEN
ter is distant from the Starting point? II
not then, should the ball exceed this point
oy SO much as an inch, would 1t not on its
return pass the starting point by an inch
and traction, and so continue to gain OH
each trip ad fnfinitum? But, on the other
hand, should the ball loose ever so little on
center of the earth?
l cannot see what difference the pres
ence of air would make other than to
bring the ball at rest at the earth's center
q little sooner. owing to its progress being
impeded by the resistance Of the air, as
well as the resistance of gravity, after it
passes the center.
"One correspondent says the ball would
have no weight when at the earth's CEN
ter. but II weight and gravity are the
same, would not the ball have its greatest
weight when at the very seat of gravity?
In other words, would 1t not take a greater
power to move It from that position than
when at the earths surface?
1T Is granted that attraction Of gravita-
tion decreases above the earth's surface In
proportion to the square Of the distance.