Evening star., 1896-12-14
AT THE lEARTH's CENTER
Close of the General Debate on the Iron Ball
Question.
Wise Men Diner-The Ball and the
Discussion of the Subject
Brought to a Rest.

the earth's center has given rise to an ex-
tended discussion and all sorts of opinions
nave been aired through the columns of
Inc Star. The problem now seems no
nearer a solution than 1t was when the
| original and apparently innocent para
graph was printed and started the nimble
pens OF The Stars readers. AS a matter
OF fairness The Star has given consider
| able space to the advocates of different
views and now prints a closing chapter of
contributions on this subject.
E. L. F. writes long letter on the sub
| Ject, In the course of which he says: Con
| cernlng the iron ball at the earth's center,
| l beg to say that my former brief communi-
cation was not intended to deal knock
out DioW TO any one--I merely treated the
| matter with what l considered proper lev
| ity IN connection with the center of the
eartn, where there is no weight. With The
star Kind permission 1 will attempt to
view the matter with the gravity proper
tlonate to the 100-pound ball at the sur
race 1 cannot agree with r. T. H. that
zoo-pound ball of yarn would weigh twice
as much at the center as 1O0-pound bail
OF IRON. fancy the relation would be the
same as the earnings of the man who some
days made nothing and at other times
t"lce as much! 1 will agree with r. T. H.
tnat the ball would rest at the center, and
II another ball came along-whether an iron
oSii' yarn ball or an inaugural ball-the
nrst Occupant would gracefully edge over
ana allow 1t room. do not agree that the
acceieration In the speed of falling bodies
a, ane same below the surface as above.
ABOVE, the entire mass of the earth ex-
er-s attrsc ctNe force; below there is a
Vary1i degree of attraction each way
equal IN all directions at the center A
near mountain will defect plumb line; and
the mass Of earth behind the ball would
soon AFFECT the momentum. We have to
consider our hole a vacuum, of course and
our pali, weighing 100 pounds at the sur
of hn IT,
~ be carried little beyond the center at
nrst. but would soon find resting place
where the force of gravitation would af-
Iect 1t eQl ally on all sides.
The pendulum Illustration of Mr.. Thom-
as doge Is faulty in that the earth exerts
Iuli attractive power on the pendulum un-
u. IL reaches vertical position. 1t is only
after 1t passes this point that gravitation
retards; but in the case of our ball prav
ration exerts IA retarding effect of CON
stantly increasing power from the instant
the ball leaves the surface"
D. j. Kelsey writes from New Haven
Conn.,, to say:
Ihe majority of the mass Quantity OF
matter) of the earth is in front of the
.s oan , .ili tne latter reaches the earth's CEN
ter, and the mass of the ball remains con-
stantly the same. though it's weight
(amount of resultant attractive force be-
tween the two bodies) gradually changes
from loo pounds to and TO 100 pounds
again On account of the mutual attrac tive
force between the two bodies and their
inertia. each will do work on the other
giving velocities, the one to the other, in
lndlrect proportion to the masses of the
bodies receiving these veiocities the earth
receiving very small velocity toward the
| ball, and the ball receiving a very great
velocity toward the center of the earth.
This effect will reach its maximum when
the center5 of the two bodies pass each
other which will be a very slight distance
from the original center of the earth. AT
| this point the resultant attractive force he
hnt anh
| have it's original mass and a certain ve-
| locity. The velocity of each in relation to
| its mass Is the amount of energy each has
received from the other, and it is just Suffi-
| cient to undo what has been done or to
carry the two bodies to the point of oscil-
| lation on the side of the earth opposite the
starting point. hat a distance less than
! the diameter CT the earth from the origi-
| nal starting point, by twice that noted
above where the centers of the two bodies
passed each other. The two bodies would
now approach each other. passing centers
at the same point as before, and return
| ing to their original positions, thus COM
| pleting the cycle to be repeated forever
Weight and Inertia.
| Mr.. b. Pickman Mann writes:
Il recommend an experiment to your cor
| respondent Inquirer and to some others
| who do not know the difference between
| weight and mass and do not appreciate
| what is called inertia. Let them lay u
| heavy ball on a pair of scales, then attach
long string to the ball and draw upon
| the string until they have taken all the
weight out of the ball, or, in other words,
| the attraction of gravitation is counter
| acted by the upward pull, which would be
| the condition of the ball at the center of
| the earth; only in the latter case gravita-
| ton takes the place of the string. Now, a
movement of the ball in horizontal line
would neither lift nor lower the ball, so
| neither gravity nor the upward pull woul1
| prevent such movement. If the string be
long, the ball might swing some listance
without moving appreciably either upward
| the experimenter hit the ball a hard AMI
sharp blew the side with his fist. Sup
| pose this ball 10 be moving rapidly in a
horizontal plane while thus having no
weight Let the experimenter put his head
| in the way and observe the result"
S. S. K. writes to The Star as follows:
Il desire to reply to Mr.. Thos w. Gill
mer's excellent article in Wednesdays Star
which comedies almost exactly with the
! theory l advanced in former articles, with
one exception, where l think Mr.. GiImer
has fallen into the common error that many
others have done in regard to the perform
ance Of the pendulum. He says: There
would be perpetual motion in a pendulum
were it not for the resistance Of the air
and friction at the point of suspension
This is incorrect as the force of gravity
Is constant and acting on the pendulum in
the same degree, whether it be rising in its
| swing or falling. Therefore gravity alone
| its lowest point of vibration whether it
had any other resistance or not to over
come
Now, I beg to suggest, Mr. Editor that
we turn the James Creek canal into this
| hole through the earth and fill 1t up with
| malarious microbes. What say you alp"
From an Octogenarian.
J. G. Goodhue, Bradford, VT, who signs
himself an octogenarian, writes as follows:
THE ball having started on it's 1900 or
| 5000 mile passage Gas it may be either, so
| far we know. 1t takes but few min
utes to gain a very rapid motion, and this
motion becomes accelerated continually by
| the law of gravity and momentum gained
| SO that l do not think 1t will be at all in
| clined to stop at the end of 1900 miles,
know the law of gravitation will not re-
main the same to the earth's center, but
gravity will become weaker as the center
| is approached. What there is is favorable
| to the balls descent. And there is enough
| to carry the ball to the earth's center had
| it's motion been ever SO slow. Then l NAV
conclude no momentum Is required as an
agent in its arrival at the earth's center
| and will suppose the momentum sufficient
| to carry the ball far past the center. but
| how far is complicated question not af-
| tecting the final result"