Jeffersonian Republican. [volume] (Stroudsburg, Pa.) 1840-1853, 1851-06-05
From the London Globe, April 5.
Rotation of the Earth Rendered
Visible.

The experiment now being exhibited in Pa
ris, by which the durnal rotation of the earth
is rendered palpable to the senses, is one of
the most remarkable of the modern verifca-
tions of theory. Although the demonstrations
by which the rotation of the earth has been
established be such as to carry conviction
to the minds of all who are capable of COM
pretending it, to which nothing can be imma-
gined to add either force or clearness, never,
theless even the natural philosopher himself
cannot regard the present experiment with
out feelings of profound interest and satslac-
ton, and to the great mass, to whom the
complicated physical phenomena by which
the rotation of the earth has been established
are incomprehensible, this experiment is in
valuable. At the centre of the dome of the
Pantheon fine wire is attached, from which
sphere of metal, four or FIVE inches in DAM
eter, is suspended so as to hang near
the floor of the building. This apparatus
is put in vibration after the matter of a PEN
dulum. Under, and concentrated within it,
is placed a circular table, some twenty feet
in diameter, the circumference of which is
divided into de grees, minutes, &C., and the
divisions numbered. Now, it can be shown by
the most elementary principles of mechanics,
that, supposing the earth to have the diurnal
motion upon its axis which is computed to it
and which explains the phenomena of day
and night, &C., the plane in which this pen
dulum vibrltes will not be affected by this
diurnal motion, but will maintain strictly the
same direction during twenty-four hours In
this interval, however, the table over which
the pendulum is suspended will continually
change its position in virtue of the diurnal
motion, so as to make q complete revolution
round its centre.
Since, then, the table thus revolves, and
the pendulum which vibrates over it does
not revolve, the consequence is that a line
traced upon the table by point project
ing from the bottom of the ball will
change its direction relatively to the ta-
BILE, from minute to minute and from
hour to hour, so that if such point were
a pencil and that paper were spread up
on the table, the course formed by this
pencil during twenty-four hours would
form a system of lines radiating from the
centre of the table, and the two lines formed
after the interval of one hour would al
ways form an angle with each other of
Is deg, being the twenty-fourth part of
the circumference. Now this is rendered
actually visible to the crowds which dai-
ly flock to the Pantheon to witness this
remarkable experiment. The practised
eve of a correct observer, especially if
aided by proper optical instrument,
may actually see the motion which the
table has, in common with the earth, un-
der the pendulum between two successive
vibrations. 1t is, in fact, apparent that
the ball, or rather the point attached to
the bottom of the ball, does not return
precisely to the same point of the circum-
ference of the table after two successive
vibrations. Thus is rendered visible the
motion which the table has in common
with the earth. 1t is true that, correct
ly speaking, the table does not turn round
its own centre, for although the table be
turned, in common with the surface of
the earth, round the earth's axis, the
point of suspension if the pendulum is
turned also in the same time round the
same axis, being continually maintained
vertical above the centre of the table
The plane in which the pendulum vibrates
does not, however, partake of the motion,
and, consequently, has the appearance of
revolving ouce in twenty-four hours over
the table, while, in reality, it IS the table
which revolves once in twenty-fcur hours
under it.