, 1874-02-19
The Foucault Pendulum Ix-
pertinent.
It will Do Performed Before Tho Chicago
Academy Of Sciences To-Day.
A Direct Demonstration of an
Important Tact,
How It Is Done.

nj NJ half IN
tnomhcra Dr tin nh;capo ACADEMY of sciepcos
i1i oyuo,,t, T., .,,a 71xosIt;ou 1,n,,1irc - ,xt.
moss tho awnc NJ t},c nonflu1u,n ae,,o,,fio1 from
t}o aouth do,nn. &vhnb proves Tint tho oarth
turns ri, 1,cr oxiR.
Tho fact TINT tho Garth turns nround on limo
within itself daly. as anv lall will do whom aont
spinning through tho air, las bcon generally be-
Uoyed by sooutit1c mon during not much moro
than two oepturjos, Yet tho truth las boon nc
ceptod during one decade for oyery single yoar
that las elapsotl since tho first droct proof Of
tas imnortant fact was furnished 10 tho inl,ab-
ItantB Of our plauot ay tho result OF a lappy nc
cidout.
No must know moro Of tho "I.ost Arts " thai,
eyon Woudell Phillips, loforo wo can dotormino
tho exact percentages OF philosophy md g,,cea-
work on which, pythagoras and Aristarcius
basot thor belief that 1'tho world n,oyos." It
is oy,tlont, ho.soyor, that there was not enough,
OF tho former olo1nont to commend it to the M.
proyal of tho aucionta or Claudius ptolenly,
who has beon compared with Hormos linn
self for wisdon, could neyer hayo To-
ioctod 1t, and advocated tho system
OF tho uniyorso which bears lia.
nn1nc, though NO have reason to bolevo ho was
not tho ono who first taught it. Eycn tho
furnished tho facts Of position from which
Koplor deduced bis celebrated laws. could not
comprehend tho fact. It required tho telescopio
evidence, furnished about tho bcg;uDtur of tho
seventeenth century, to onablo us to bolioye that
such thing is oyon possible, Ouly when
it was found that tho sun and many other bodies
aro much largor than our oarth, gus It realized
tlat to reject tho theory Of tho oartls rotation
as absurd, involved tho much greater abaur1ity
Of suppoeng that many millions Of stare, oacl
larger thau our earth, tly around us every twcn-
ty-four hours, III circles tho crcumtoronccs Of
which sceu, almost infinite.
This argument tho ycx,actio ad a1spytlan,, os
tho logicians call it, was, till very recent date
supposed to bo tho most coeont one that coulj
DO adducod to provo tho TACT Of tho earth's
diurnal rotation. Even In tho prcseut coutury
,yo find Prof. Woodhouso Whose knowledge Of
physical astronomy entities him to a ,auk mt
fur below Laulaco and Nowton, wroto tbat, "We
must. lovoyor. bo content at nresnnt tn faxn
for granted tho truth of tho hyuothosis of tho
eortlls rotatiou. If It continues tn crnain sim,
piy and snt;sfactoriIv nthcr nstrononicol nloro-
me1la than those already noted, tho probability
Of it's boing truo hypothesis will 70 on iucroas
ing. We shall ueyor, indeed, arrive at q tin,e
when We ehall bo able to pronounce it absolutely
proved to bo true. The naturo of tho subject
excludes such d possibility"
4 direct and unmistakablo nroof was. how
over, soon furnished. About tho middle of tho
present century, A1. Toucault, Of pariB, in
Franco, noticed tho deviation OF n weight sus
pended by string from a high coiling. wb,ct,
lad been accidentally rot III motion. Tn tho
epring OF 1861, tho scientific world was eloctri-
fled by tho first exhibition Of tho Foucap,t
pendulum experiment, tho weight being
suspended from tho domo OF thu Pan.
tllcpu i'll paris ncarly 200 foet hrT,
The experiment was soon roncated in
many OF the cities of Europo beforo a3n,r;nc
crowds of sayants and others in eovorol n,aco. in
tho Eastern Statcs Of Amorica. aud ut two or
tkrco points in what yas tlou tho Vest. g,nca
that time, however, tho experiment Inns becn
neglected, though not forgotten by those who
Witnessed it. But it is lust as reccssarythnt t1o
rising generation eLould have ocular proof that
tho world moves, as 1t Was twenty-tlroo years
ago, TINT many who are now passing into tia
aorc and yellow leaf should then bo convinced m
the fact,
Several of tho present moubers of the Chi
cago Acadon,y Of Sciences witueasefl tho exnor;-
ment more than score Of years aro. when our
city Ind barely missed t,,e nnrio1 of hor infoncy
bciug tllon about to make lcr first conuoction
with tho East BY rail, Some of those ront1oman
hayo, several times in the past thourht ovor tho
possibility of conducting it m n rro,,or aco,o
hero but suitable building was want;nr TIo
shot-toyer Of i. ", Datchford 4 Ca. il ,,iol,
enough, but lacked tie room necessary tn
permit tho public to Wow tho phenomenon. At
last, tho noble Exposition Building affords tho
long-wished-for onnortunity Of demonstrating
to Tho Qo.ahcad peoplc Of Cbicaco that nil tho
rest of tho world is moving, as vol as tl,oy. It
is no wonder TINT tho Academy of scencca, nm
tbs first suggestion, should decide to furnish
(. popular proof that tho earth turns On its oxjs,
Tho Directors of Tho ExpoRit;on Buiidinc
wore kind enough to place tho str1c-
tnre ut tho disposal Of tho Academy
for the purpose the architect of tho bnildIpr,
A1r, Doyincton, gaye a portion of lis valuable
time to direct the required removal If obstacles
in the way of tho swinging line aud the conor-