American telegraph. [volume] (Washington [D.C.]) 1851-1851, 1851-05-29
ROTATION OF THE EARTH.

10 the Editors Of the american Telegraph.
GENTLEMEN: viii you allow me a small space
for some unphilosophical speculations upon this
subject? ! am neither man of science nor one
wholly Ignorant Of laws, so / may hope that
what have to say will be read
The newly discovered principle that the mo-
ton of the earth can be demonstrated by the
vibrations OF pendulum has attracted the no.
tice of many persons in the Old World, and is
now the subject of experiment at the Observa-
tory at Cambridge, and at the Smithsonian In
stitution in this city. | have Witnessed the
experiments in the hall of the latter place with
some interest for several days, and I observe
the following results Et
lst The ball Of the pendulum is swung at
distance of about forty-fve feet from the roof.
When the pendulum is set in motion from north
to south, describing an are of about thirty de-
grees, thereis perceptible change of the north
end of the arc towards the east ,se
This apparent variation is the principle, and
is said to be caused by the motion of the earth
around its axis. The London Illustrated Nescs
of the Sd instant, gives an engraving and an
explanation of an experiment. and says: "The
plane of vibration never changes" The plane
of vibration is the plane through which the cord
of the pendulum moves. Now, if the position
of the plane of vibration is considered in re
spect to the north pole, or the north star, or
any visible, fixed point connected with the
earth's orbit, it does change. Because, when
started from north to south, the plane is parallel
to the magnetic needle, and after few moments
motion it is not parallel .........
We have always been taught to believe that
the magnetic needle points to the north star
and never varies, (only so much as is consistent
with the law of magnetic yariation.) If then,
the change of the plane is only apparent, while
it is the table or floor that moves round, its po-
sition must be considered with some point in
space not connected with the motion of the
earth or the solar system. And where that
point is, remains to be discovered.
I'd. If the bah Of the pendulum is drawn north,
and let go with a slight impulse towards the
east, an elliptical motion is the consequence,
and the change of the plane towards the east is
faster, (going round thirty degrees in seven
teen minutes and the transverse diameter in
creases while the conjugate diameter decreases;
and
Sd. If the impulse is given towards the west
the same change in the diameters takes place;
but the change Of the plane of the eonjugate
diameter is from north 10 rest.
If the diurnal revolution Of the earth causes
the plane to change to the east, when it is set
in motion parallel to the earth's axis that mo-
ton of the earth must be the cause of variation
when the ball moves in an ellipse. And if it
is the cause Of the variation from north to east
what is it that causes the variation from north
to west, when the motion through the ellipse is
in the contrary direction? Cause of motion APP
piled in the one direction on the one side of an
object cannot make il move two ways
Now, what are the laws Of motion which
cause, first, the increase Of the transverse diam
eter, and, second the variation Of the plane of
the conjugate toward the west.
When these two questions are answered, and
my first speculation is proved erroneous, (for am
open to conviction and desire correction then
viii believe that the motion Of the earth can
be demonstrated by the vibration of a pendu-
lum. As it is, / believe that in these variations
of the plane of vibration, and the eccentric mo-
tions of the ellipse, there exists some principle
Of nature, or some new law Of motion, which is
entirely hidden from science; and hope that
the Faculty of the Smithsonian Institute may
honor themselves and their institution, and add
to the already immensity of human knowledge,
by discovering that principle or law.
Yours, respectfully, A. +. II.