The southern press., 1851-05-03

The RoTATIos or the EARTH RENDERED
VIsIBLE.-The experiment now being exhibited
in Paris, by which the diunal rotation Of the
earth is rendered palpable 10 the senses, IL Ger.
tainly one Of the most remarkable Of the mod
ern yeri6cations Of theory. At the cent-e of
the dome Of the Pantheon fine wire il attached,
from which sphere Of metal, four or FIVE 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 a pendulum. Tn.
der and concentrical with IL, Is placed circular
table, come 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 principle, of
mechanics that, supposing the earth TO have the
diurnal motion upon its axis which is imputed 10
il, 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 i
suspended will continually change its position
IN virtue Of the diurns motion, so NJ 10 make n
complete revolution around its centre. Since
then, the table thus reyolyes, and the pendulum
which vibrates over il does not revolye, the con-
sequence ~, that line trnced upon the table
W ~ pun iFoU potion OF Tho
ball will change IFS direction relatively 10 the IN.
bic from minute 10 minute and from hour 20
hour, so that il such point were a pencil. and
that paper were spread upon The table, the eourse
formed by this pencil during twenty.four hours
would form system Of lines radiatinp from tho
centre Of the table, and the two lines formed
after the interval Of one hour would always form
an angle with each other Of Is deg, being the
24th part Of the circumference.
Now, this IS rendered aetualy visible 10 the
crowds which daily flock 10 the Pantheon IN
witness this remarkable experiment The prac.
used eye OF correct observer, especially if aided
W proper optical instrument, may actually
see the motion which the table las in common
with the earth under the pendulum between two
successive vibrations. 1t is, in fact, apparent
that the ball, or rather the point attached 10 the
bottom OF the ball, does not return prec;selv %
the same point Of the circumference ~ the tsble
after two successive vibrations. Tins il ron.
dered visible the motion which the table has in
common with the earth
1t is true that, correctly speaking, the table
does not turn round BY its centre, bot Turns
round the axis Of the earth nevertheless. the
effect If the motion relatively 10 the pendulum
suspended over the centre Of the table is pre.
cisely the same as il 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 is turned
also 10 the same time round the same axis. be-
ing continually maintained vertical above the
centre OF the table. This plane in which the
pendulum vibrates does not, however, partake of
lnls motion, and consequently has the appear
ance oil revolving once in "a hours over The table
while. IN reality, it is the table which reyolyes
once 10 "a hours under it-Londor Times.