Weekly national intelligencer. [volume] (Washington [D.C.]) 1841-1869, 1851-05-31
THE PARIS PENDULUM EXPERIMENT.

ron THE NATIONAL ISTBLLIGENcER.
As find it difficult clearly how the Paris expe-
ment proves the rotation Of the earth, give few lines
which think will satisfy every reader. The experiment
consists in hanging round weight say five six or
pounds by fine wire twenty feet long. The weight then
put vibrating, and let suppose north and south drec-
ton white rod is placed the floor under the weight
and exactly in the direction Of the plane Of vibration Now
is found upon trial. that atthe end Of sixteen minutes the
weight instead Of vibrating right n upright plane the
rod will swing from the southwest to the northeast an
angle Of about four degrees with the pine rod This they
say, sufficient prove the motion of the earth on
axis and thus they prove their point First It pho-
sophcal TRUTH proved by and experiment that Vi
bang pendulum, although carried BY the point Of suspension
in any directions will still vbrae in planes parallel each
other Now to be Of this essential part of the proof
get eaden bullet, and with penknife cut little hollow
all round the lead in order to tie silk thread round i'll get
small board, say half shnge put the Of the
table let twelve fourteen inches project from the table,
and place weight the end of the board to keep the
table hang your little pendulum, with eighteen inches Of
thread the top of the board and swing the bullet in the
direction Of the joints Of the flooring board it will be found
that the pendulum weight will swing n the direction Of the
joints although you smoothly work the single round the
of the table centre that is the plane Of vibration
| continues parallel to its first position.
Secondly: Take small map Of the world, and suppose
for moment that pendulum put in motion in latitude
40 degrees and in the direction of the middle meridian
the map, and that the earth turns round for hours Their
my white rod under my pendulum will have the position
the second meridian the right hand the map but my
pendulum weight will swing parallel to its first direction
by laying ruler parallel to the middle meridian, and ove
the place Of the pendulum. will be that my meridian
rod makes angle with the direction parallel to the midd
meridian. Or, still BETTER if you produce the second meri
dian beyond the north poe and produce also the first mer
DIAM it will be found that they make angle Of 6ftee
degrees with each other. II appears from this that if tn
earth axis this result would be produced but
the earth had rotary motion the weight of the pendulum
would continually swing the white rod Hence the
pertinent is taken as sufficient proof Of the earths rotation
If we pursue the above trial Of the map, shall easily
that at six hours after the pendulum started the white rod
will have the position Of the outline meridian of the hemi-
sphere and at the north pole find that this meridian is
at right angles to the rs the line Of the orgins direction
Of the motion Of the pendulum; and as The pendulum will
vbate parallel its original direction, it is evident that the
rotary motion of the earth alone produce the continual
deviation Of the direction Of the plane, passing through the
Of vibration in the experiment It lie in fact how
ever the Unite rod that changes its position in space
IF any other direction besides north and south be taken
the first direction of the vibration Of the pendulum the abov.
explanation still applicable for il you suppose your white
rod placed at any angle with the meridian and vibrate the
pendulum in that direction it is clear that your meridian
changes its direction in space Of is degrees in hour
follows that your white rod changes the quantity
space from its first position but the pendulum continues
parallel to its first direction the white rod must make an an
gle Of fifteen degrees with the direction Of the pendulum
the end Of one hour, and on.
Il will appear from the above that it is rather ridiculous
asserted that person the earth moving when OBJ
serving the experiment. for it requires principles and
ing to which the generality Of minds familiar The ex
pertinent has been repeated in many places through th.
country, viz. Cambridge Georgetown College, &c. G.