Richmond daily times. [volume] (Richmond [Va.]) 1850-1853, 1851-05-14


OF Nh Foucals memoir, explaining his experimental
demonstration Of the Earths rotation on its axis.
The notion OF the rotary movement of he earth has
now become 40 general, it has VIGOROUSLY passed
from the domain ofscence into that Of vulgar ideas that
it would seem supetluous to seek to establish il hy ad
dliona testimony. Nevertheless when 1t is considered
that the principal arguments in support of this move
men are drawn from the observation of celestial phe
nomena, one Will perhaps be disposed to accord some
attention 10 the results Of experiment which d,spen
SEES with the necessity OF scanning the heavens and per-
mlts the fact OF the ears rotation to be educed from
mere nousenoid experiment AS upon the broad ocean,
with no shores in sight, the helmsman his eyes fixed
upon Inc compass takes cognzance of every variation
In the course OF his ship, the nhabtant Of the earth
may make Tor himself by means OF the pendulum, a
sort OF compass, which, set arbitrarily in absolute space
Will, by its apparent notion reveal 10 him the actual
motion OF the globe which supports him. When the
magnetic needle, which does not cease to point toward
inc north appears to turn in one direction s mmedi
atey concluded that the ship itself is yeering in the
o'er ny and by, when we shall the plane OF oscii
lalon OF free pendulum constantly deviatng in GER
tam direcion we shall likewise conclude, presence of
TINS plane, which should turn we that are
turning IN the contrary direction. Upon this point then
we all be again constrained to correct by reasoning
me testimony OF our senses. Upon putting the pendu-
lum IN motion, we will commence by establishing
founding ourselves upon essential property matter
lnertla-hat the plane determined by the oscillations
cannot turn about the vertca and it. contrary to the
most positive laws OF mechanics, the pendulum appears
TO US to have movement OF rotation CONFIRMED to that
OF the celestial sphere we will struggle against the an
pearance, and we will apply ourselves 10 the ground
TO the objects surrounding u.s. this movement op
posite direction.
AT the time it behooves us to acknowedpe that
II at the present day the new expermen4seems concu-
sVe and decisive we must thank Tor it the progress of
the times In the hands of Copernicus ard of Galeo
this experiment would have only proved one perpe yitv
the more, by of the difficulty they would have
had in selzng the link which connects with the move
nen OF me earth Nfs then, rather consequence of
this movement than proof support OF an undispued
truth, that we would produce here for il, which ia i'm
possible the!e be yet found who persist In ma.
king the sun evoye around the EARTH is certain that
Tor those preudiced minds the spontaneous deviation of
the plane OF scilation of pendulum would remain
without effect But considered as simple yerifcation
this experiment has at least in its favour the advantage
OF face execution and assured success Tho nbennmm
enon develops itself calmly 1t is fatal irresistible like
the superior cause which produces it. You feel az Won
see II begin and progress that it in the mower Of
me operator to hasten or retard the manifestation
Every man put the presence OF the fact whether con-
verified or not TO prevalent ideas, remains for some mi
nutes thoughtful and SILENT and generally retires bearing
away with him more pressing and livelier sentiment
OF our lncesSant mobility in space.
AS we have already said, the observation bears mon
the movement OF the pendulum, one of the most pre-.
clous instruments OF physics one Of the finest concep.
IONS OF Gahieo. The simple pendulum is pure abb
stfacton, creation oil the mind which it is impossi-
bic to realize materially. LII supposed 10 be formed of
heavy molecue, suspended by flexible, pextensibe
thread without weight attached by the upper extremity
to fixed point, and intended preserve an unvarypg
distance between the fixed point and the moecule
The perfect fexibty OF the thread at the point OF al
tachment permits the molecue to move upon the eur
lace OF sphere OF which the thread is the radius and
the fxed point the centre Ia practice approach as
nearly as possible the conditions of the simple pendu
um, by causing very dense metallic sphere to repre
sent The heavy mo!ecue, and the most slender thread
ha can De USED without rupture to represent the mathe
NAUTICAL thread Furnished with pendulum OF this kind
the physician verhes, very nearly, the laws indicated
by mechanics as those which would be illustrated by
the movement otthe simple pendulum.
1T IS thus that this physical penduum ran,nved t,y
or three degrees from the vertical and then left
to ITSELF passes and repasses by that vertical desert
tent, but the duration of which remains sensiby The
same from the largest to the smallest. This fuuda-
mental property oil the pendulum, discovered by Cali.
leo, and known by the oame of isochronsm, has been
ior more Than two centuries the object OF nnumerable
observations and Huyghens, by applying the pendu-
lum to clocks, p' oduced the valuable instrument
Tor the measurement OF time. But the clock-maker
IN taking possession of the pendulum has caused to-
undergo modification which masked another of lis re
matkable propertes-the very one which we have lust
brought INTO IT.. play mean its property OF faithfully
pcation ofhe pendulum TO clocks it has been found
expedient to suspend not by thread but by means
oil knife or plate, which compels it to vbrate in
plane determined by the construction, and permanently
set in correspondence with the immovable pieces of
the machines whence ii follows that the pendulum of
the clock makers no longer oscilliaes freely about
point upon the surface OF sphere but in de-
terminate arc and about fixed axis
In order to demonstrate the movement of the earth
1t has been necessary to break this connexion of the
plane OF oscillation, with the point OF attachment and
come 0ack 10 the Tree pendulum. 1t was necessary 10
deliver the admirable instrument of Calico from the
bonds which habituay attached it to the earth and re-
establish with Its original Independence its natural re-
a'lons WIN absolute space exact sphere, suspend
ed from fixed point by metallic thread, as slender
as homogeneous, and as exactly cylindrical AS possible
such 49, up to the present time, in all the simplicity of
alileos invention, the instrument the best adapted to
give to man a sensible sign of the rotation of
the globe upon which he dwells. The moment it is
put In motion belongs in sort 10 the celestial
space and II yet holds by point TO the EARTH it is
only mat may continue present to the eyes OF The
spectator and offer TO him the evidence othis own mo-
bty. W. nv
It is, in fact easy to show by experiment up to what
point we may count upon the independence OF the
plane OF oscillation.
Before contemplating directly the movement of tine
eaith ltsel, which by Its slowness cOmpes the resort
TO apparatus OF extraordinary dimensions, let us in
sta upon table, which we will make move at plea.
sure, small pendulum-a ball OF lead suspended by
thread. The room in which we operate shall renre
sent the universe; the table shall be for US the EARTH
above circle traversed by different diameters. of
which the point OF intersection corresponds with the
direction OF The pendulum when at rest. The pendu-
lum the support, and the circle form connected
whole, complete apparatus, which we place, first, at
the centre OF the table. Youthen take hold Of the ball
OF lead, draw from its position of equilibrium fol-
loving the direction OF one OF the dameers of the cir
cIei then let go, and commence your observations
What happens then! The most simple and evident
thing in the world ] he moment it becomes free the
pendulum starts toward The central point passes it by
virtue OF the velocity has acquired returns to again.
passes and repasses until its movement ceases over
That celre, having oscillated in an unvaryng plane
IN the direction OF the diameter along which had re-
ceved the primitive impulse. Let one seek 10 ohserva
the vibrations oil the pendulum, by COMPARING them
with some fixed points the table, upon The wallis othe
champer and he will In the be conducted 10
the conclusion That the plane OF oscillation is upchane
ing. But it, while the pendulum is in NAV Won ca,so
me Table gently and smoothly to turn upon tsef. what