Year: 1864

ton, though the point of suspension be,
at the same time, revolving; for when
about to return from an outward excursion
it is influenced by single force, and can
therefore move in but one direction--to-
ward the lowest point of its arc. Having
reached that point, it has acquired suffi-
cent momentum to carry it IN The same
direction to the opposite point of rest
Being here under the influence of the
same force acting in the same line of di-
rection, it must, in reference to absolute
space, return by the same path, although
the point of suspension may, in the mean
time. undergo a revolution.


1t is not therefore difficult to conceive
that pedulum, vibrating at the pole of
the earth, will apparently describe COM
plete revolution around the graduated "a
BILE once in "A hours; for since, in this
case, the axis of the table comedies with
that of the earth, if we suppose the latter
body to have the diurnal motion usually
ascribed to it, the table will be carried for
ward at the rate Of Is. degrees per hour
under the plane vibration; which, though
fixed in regard to space, appears to re-
volve, on the principle of transferred mo-
ton


AT the equator, the plane of the table
lies parallel with the earths axis; hence
the latter is at right angles with the axis
Of the table; and the only effect of the
diurnal motion (supposing there is one)
will be to carry forward on the circumfer-
ence of the great circle, the table, and,
with it, the plane of. vibration, without
disturbing their positions in relation to
each other and toabsolute space. A priori
therefore, we should infer that there is no
deviation at the EQUATOR


he case of pendulum vibrating at
places intermediate between the pole and
the equator, is not susceptible of so easy.
an explanation. The conditions it under
goes are SO numerous and variable as to
render an exact conception of its motions
difficult, and full description of them in
writing impossible. Nor is it necessary
for by aid of terrestrial globe, having
small circular plane of paper marked with
the cardinal points, tangent to the surface
ut any latitude, (say 45 degrees) the ex-
pcrimenter will be able readily to show


First, That the circular table and plane
of suspension always maintain their reia-
'iCe positions unchanged during the revo-
luton of the sphere; the ponto suspen-
sion being constantly preserved vertically
Jver the centre of the table.


Second, That in consequence of its
rotation around the axis of the sphere,
the cardinal points of the table are ever
revolving, in respect to stationary point
in space and,


Third, That therefore the plane of vi
bration which is necessary fixed must .ap-
pear to advance over the table from Vest
TO east, like the hands of watch when
its face is upwards; although in reality
the table moves in the opposite direction
as if turning round its own centre.


In conclusion, we may be permitted to
remark, that the experiment of Foucault,
Illustrating, as it does, one of the most
important topics of primary instruction,
deserves the careful investigation of the
teachers in all our public schools; and
should be regarded by them, not as a. curl
osity of science, to be turned over to the
management of the SaUan, but as an i'm
portant and permanent accession to their
professional resources, to be boarded and
used for the credit Of the fraternity; as
we'll as for the benefit of their pupils.


j. b. BEACH.