The Middlebury register. [volume] (Middlebury, Vt.) 1850-1882, 1851-05-14

Yankee Blade.
The Rotation of the Earth Rendered
! visible.
The experiment now being exhibited
in Pafis, by which the diurnal rotation
of the earth is rendered palpablc to the
senses. is certainly one Of the most re-
mark able Of the modetn verifi5aiions OF
theory. At the centre Of the dome Of
the Pantheon a fine wire is 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 pendulum. Under aud
concentrlcal with it is placed circular
table, some 20 feet in diameter, the cir
cumference Of which is divided into de.
grees, minutes, &c, and the divisions
numbered. Now, it can be shown by
the most elementary principles of me.
chanics that, supposing the earth to have
the diurnal motion upon lis axis which is
imputed 10 it, aud which explains the
phenomena Of day aud night, &c, The
plane in which the pendulum vibrates
will not be affected by this dlurnnl mo-
ton, but will maintain strictly the same
direction during twen,y-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 a
complete revolution round its centre.
Since then the table thus reyolves, and
the pendulum which ribrates over it does
not revolve, the consequence is, that
line traced upon the table by point
projecting from the bottom of the ball
will change IFS direction relatively to the
table from minute to minute and from
hour TO hour, so that il such point were
pencil, and that paper were spread
upon The table, the course formed by this
pencil during twenty-four hours would
form system of lines radlaiing from the
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 degrees, being the 24th part
of the circumference.
Now. thi, is rendered actually visible
to the crowds which daily flock 10 the
Pantheon to witness this remarkable ex-
pertinent. The praciised eye of cor
rect observer, especially if aided by
proper optical instrument, may actually
see the motion which the table has in !
common with the earth under the pen
dulum between two successive vibrations. |
Ii is, in fact, apparent that the ball, or
rather the point attached to The bottom |
OF the ball, does not return precisely 10
The same point of the circumference of !
The table after two successive vibrations.
Thus is rendered visible the motion
which The table has in common with Tie
earth.
it is true that, correctly speaking, the
able does not turn round by lis centre
but turns round the axis OF the earth.
nevertheless, The effect of the motion
'elatisely 10 the pendulum suspended
'ref the eeMfe Of the table is precisely
he same as II would be If the table
moved once in "a hours round IFS own
'entre, for although the table is turned
II common with the surface of the earth
ound The earth's axis, The point of sus-
tension Of the pendulum Is turned also
n the same time round the same axis.
'eing continually maintained vertical
fbo'e the centre Of the table. The
lane in which the pendulum vibrates
'oes not, however. partake of this mo.
ion. aud consequently has the appeat>
nee Of revolving once in "a hours over
he table, while, IN reality, it is the table
rifich feSolyes once in "a hours under
London Times.