, 1874-02-24
TIE PENDULUM EKPERIh1.

LIE EGNoOoOA IL 62AEC1A1MGNA As
The big pendulum was in motion yeateEdny
Afternoon from hnlf-past o'clock till 8, and was
visited by good many pooplo. It was fearod
thnt the high wind would mar tho SUCCESS Of the
experiment by causing shifting OF tho point OF
suspension In tho dome. The greatest displaoo-
meut noted was rather loss thau quarter OF m
inoh 10 the eastward, which did not nppreolably
chango the direction Of the movement. satur-
day the pondulum will swing from $3.50 till
o'clock, for tho benefit Of teachers In tho pub
liz md other schools. Tho explanation Of tho
phonononon, will begin precisely Of Z. Private
Df. bridge, No. 287 West Monroe street, between
and Z O'Clock in tho evening.
TILE CENTRIFUGAL FORCE.
A correspondent asks at what distance from
tue aurfaeo would body lose weight and eea5o ~,
to be carried round by the enrth! In her daily
rotation. Ho seems to think 1t very hard quos-
tion. Tho limit OF tho atmosphere over tho
tho ratio bctwccn tho total attraction at tho
equator and tho loss Of weight there. as duo to
centrifugal force. For Tho oartl, tho distance
IL sbo1t 2o miles S9a tor tho gr To-
4 RENEWED 1a1puLsE.
as g. FIST Fssp K % esgi ssg IL ioona susae.on Of
without Interfering with its plana q oscillation
hoavy eylindos Of tIo accurately bored throughout
It's cnsro length Into this tsrrel drop long plung-
3A-tou accurately tnFnEu 10 ut tHe por4 ot tho cyn
vided with 1ncans Of lifting 1t, anu tho lower ond
Ehoud terminate In abrpttyf0Ened conical point,
for the attachment Of tho pendulum wire.
By this adjustment, . renewed Impulse Ii given to
tno os sn 1oanr " tny ea'sng ts gung
tho time when the ball ia passing from tho perpendic-
ular toward the polnt Of greatest esongaton. Thla
movement may DO repeated during few oscillations
till tlo initial momentum Of the pendulnm III at-
tainod, when 1t may be tnternitted till agatn nee
essary.
There reasons why this plan Is not desirable
when precision In estimating the rate Of rotary
mont Of tho earthd plano fs aamcd nt. but tho writer
sees no reason why for purposes OF popular demon-
atsaton, # inay not 10 used 10 advantage. It Is
tn that the rod 10 retained III the cylinder without
play shake, aud that 1t ho most carefully adjusted
90 Tho perpendicular It's movement may be entrusted
To- one or lnen who by practice have acquired
Any desiring to test tho practcabil!ty Of this
suggeston may Dc 10 by extomrorizing an apparatus
ia follows: For tho rod ordinary pen-lloltler
and Tor tho cylindort y hpoo1. Attach convenient
weight to thread and having made this faat to ono
through the spool Supporting tho latter On the cor
nor Of ableoaf other suitable object ca,so the
weighs to v,brato slowly by lifting the plungng-
as suggtsted te motion of the weight viii be aceeer-
Ated In a atrildly manner.
Thia plan was applied by the writer to Toueault's
experiment many yeara ago. Tho pendulum was sue
tosyfully kept In motion, but the inaccurate adaptauon
tho plungor aud cynlcr and the imperfect settjug
of the latter, deprived tho result OF Interest. d.
AAswEn.-Jlia plan IL undoubtedly IN e1col.
!ont one, 1t 1t bo dealrod to ropoat the oxpori-
mont OIL a smaller scale. In the Exposition
building 1t ia not necessary. nB tho great longth
OF the pendulum inaures Its vibration through o
considerable distance for a longer period OF time
than most pooplo care to spend IN watohing II: