The southern press. [volume] (Washington [D.C.]) 1850-1852, 1851-05-03

THE ROTATION OF THE EARTH RENDERED
VIsIBLE.-The experiment now being exhibited
in Paris, by which the diurnal rotation of the
earth is rendered palpabe to the senses, is GER
talnly one of the most remarkable Of the mod
ern Notifications of theory At the centre of
the dome of the Pantheon fine wire is attached.
from which sphere of metal, four or fse inches
in diameter is suspended so as to hang near the
floor of the building. This apparatus is put in
vibration after the manner of pendulum I'm
der and concentrical with it, is placed a circular
table, some 20 feet in diameter, the circumfer
ence of which is divided into degrees, minutes,
&c, and the divisions numbered Now, il can
be shown by the most elementary principles of
mechanics that, supposng the earth to have the
diurnal motion upon its axis which is imputed TO
it, and which explains the phenomena of day
and night, &c, the plane in which this pendulum
vibrates will not be affected by this diurnal mo-
ton, but will maintain strictly the same direc
ton 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 diurnsl motion, so as to make
complete revolution around its centre. Since,
then, the table thus revolves, and the pendulum
which vibrates over it does not revolve the con.
sequence ls, that line traced upon the table
by point projecting from the bottom of the
ball will change its direction relatively to the Ia
bic from minute to minute and from hour TO
hour, so that If such point were pencil. and
that paper were spread upon the table, the course
formed by this pencil during twenty-four hours
would form a system Of lines radiatinp from tho
centre of the table, and the two lines formed
after the interval of one hour would alwavs for,,
an angle with each other of Is deg, being tho
oath part of the circumference
| Now, this Is rendered actually visible tn tbe
crowds which daily flock to the Pantheon 10
witness this remarkable experiment The prsc-
tised eye of correct observer, especially if aided
| by proper optical instrument, NAV actually
see the motion which the table has in common
with the earth under the pendulum between two
successive vibrations. 1t is in fact, spparen,
that the ball, or rather the point attached to the
| bottom OF the ball, does not return precisely to
! the same point Of the circumference of the table
after two successive vibrations Thus ia rem.
dered visible the motion which the table has in
common with the earth
II is true that, correctly speaking, the table
does not turn round by its centre, bnt Turns
round the axis Of the earth nevertheless, the
effect Of the motion relatively to the pendulum
suspended over the centre Of the table is pre-
cisely the same MS it would be if the table moved
once in "a hours round its own centre. for al
though the table is turned in common with the
surface Of the earth round the earth's axis. the
point of suspension Of the pendulum il turned
also in the same time round the same axis be-
ing continually maintained vertical above the
centre of the table. This plane in which the
pendul"m vbrates does not. however, partake of
I IBIS motion, and consequently has the appear
aDce OF revolving once in ~ hours over The table
WHILE in reality, il ia the table which revolyes
once in ~ hours under it--London Times.