The daily union. [volume] (Washington [D.C.]) 1845-1857, 1851-07-16
From the Boston Courier.
AoeAsson OF shs Earah.

the rotation OF the earth on It's axis and that sno,ber
experiments TO be made at the ship house the navy
yard all under the direction OF Professors Bond and
Horsord We also learn that Mr. Bond tried the exper-
nent at the University with silver tcirs, and gave
very learned description OF The result This all very
well but appIehend there is rather much paade
about The matter Great credit however, due 10 Mon
sleur Foucau for his discovery OF simple and con.
elusive mode of illustrating the subjects but after his
experiment and explanation, II is simple the alpha.
bet TO every astronomer, any toerably familiar
with the theories oil The pendulum and OF the rotation of
the EARTH and II is easy 10 test II as 10 weigh pound
OF Hour IL may indeed be done with suuer toire sup.
porting the pendulum, and II may also be done precisely
well, and probably better, by iron WIRE because
more tenacious than silver II may, possibly. also be
tested TO conclusive result by string, though not with
so much precision but that the results be produced
conclusvely, by pendulum forty feet long, was abund-
anily iesed by The dIscoverer IN Pans, and doubt not
that tendency TO The result could be shown in
room ten ieet high The problem having been once
solved by Mons Foucault. tine experiment depends on
few very simple and well known principles.
The principles these The earth fevolyes on an
axis once day. II spectator were at stand point di.
recly over one OF The poessay the North poIe-some
my feet above the surface of the earth, and could look
down on round table circle placed the polar point
OF the ears surface, he would the table urn round
once IN twenty flour hours The effect would be
observed if the table were placed at lower latitude
say the meridian OF Boston, AZ deg. 90 min-provided
that the spectator could the table from fixed posi-
ton This may be illustrated by placing wafer on an
apple a! or near the STEM and considering the stem
the North poles and gradually turning round on its axis
Inc waller VIII make a complete revolution with the
apple; but with the earth the difficulty is 10 find any
fixed stand point for the spectator above and beyond con-
tact with the earth. Mons Foucau conceived the idea
OF testing The same result by means OF the pendulum
suspended "a peculiar manner. Common pendulums
are suspended on fixtures which revolve with the EARTH
anu thus are Intended to turn the pendulum itself with
The revolution OF the earth.
M. Fqucaulrs pendulum is composed of so heavy
weight, and is attached to wire or gament SO much al
tenuaed that single revolution OF the fixture from
which 1t is suspended would not materially disturb the
regular oscillations OF the pendulum Thus, 56-pound
50 feet long, would not be materially disturbed by sim
gle revolution of the fixture. If properly set in notion
ihs pendulum would vibrale all day. in the line OF osc
started in line due north and SOUTH il would continue
to oscilate the line all day Nevertheless the
hxtIre above TO which it is attached and the table
circle under IT, would IN day of twenty -four hours
revolve completely around by the rotation OF the earlh TO
which they were attached Indeed all the surrounding
objects attached to the earth would actually make rev.
ouhon excepting the weight suspended 10 the wire or
the pendulum. This pendulum would continue to
march IN It's original line of oscillation on It's original
line due north and south, not relative TO the earh but
north and south, relative TO the universe or universal
space But observe everything attached to the EARTH
and especially the round table below the pendulum,
would turn round and these revolving objects would
cause the pendulum TO to devate from its primal
oscillations north and south. The table below would
actually revove IN the opposite course OF The hands OF
Waich placed ON the eahs surface, and the pendulum
would seem TO deuiafe gradually round in the opposite
decton passing IN succession, all round, the radi
OF the table below Now, the reason why the pendulum
does MOI actually deyiae, as seems TO devias, is be-.
cause The wire on which il is suspended SO very long,
small and attenuaed that singh twist or revolution OF
so feeble gament has not the power disturb the great
weight 81 the pendulum so to it to revove with
the point from which II Is suspended To all lnents and
purposes. therefore, the pendulum oscllaes freely as
were attached TO nothing earthly, and had the power
vloIae IN minnie space. II moves independently while
Inc earth and all surrounding objects actually round
II were easy TO perceive that IT, instead OF small long
wire, the pendulum attached piece of tin plate
an inch wide and four feet long, and If one end of the lin
had hx,r ~
the pendulum while 0sclatng laeray, would Ievolve
para pdssu with The fixture to which 1t was attached
The whole apparatus would thus revolve together with
out showing any variation between the rotation of the
table and the oscillation OF the pendulum On this prn
eple the pendulums OF ordinary clocks ucled
But NJ Foucaulfs pendulum is very different above
described
Bearing in mind these principles. suppose we put
plate OF iron one foot in diameter in ceiling III feet
high. IN such manner that the plate revove freely
on vertical axis-weld piece OF wire OF the diameter
OF pin and 40 feet long 10 the OF The revolving
plate, and suspend 56pound weight to this wire Now,
nus plate be made 10 revolve gradually once round, II
Will have very lite or visible effect the 36pound
weight that rs 10 say, will not the weight TO
volye Immediately and pari ,pasu With ~ revolving
plate above even i the weight "a = osciIla,r
a many smes so a. - sss sI i.s
weigh. = s;.sse 49, ll y - The
:; (: 81! !. a: s: IS !.
" ou446t0n 81 -! DSRss would be the effect
ol 80 ts - llne plate OF single twist OF the
~DoG1hss Suspended a long and small wire il this
weight were put 10 motion as pendulum-osea ling
due north and souihiis great power of oscillation
would the more ehecluay and perfectly epoy
tendency 10 be dstbed by the rotary motion oil the plate
when the welded while any liked table or
circle below. and attached the EARTH would gradually
evove round IN twenty -four hours with the rotation oil
the earth.
Now, this precisely the effect OF the rotation of The
ear IN an rtr All had In "A Upta Hy
the simple process OF the rotation OF the earth axis
the ceiling Tevoves round once twenty Jour hours
is represented by the circular plate the ceiling, and
also by round table circle the floor below. Bot
single turn rotation twenty. Tour hours has
appreciabe effect on the heavy pendulum IN motion. II
sull osciilaes due north and souih-thai due north
and south relative 10 infinite spaee-whe the circular
plate above and the circular table below, being fixed 10
The earth, revolve gradually in twenty -four hours
from west 10 east in the reversed motion OF the hands
OF watch placed on the ground Hence, II we watch
carefully the oscillations OF this pendulum, thus freely
moving, we shall the line OF lis march
cilaton, seemingly travelling round, and marking the
radii Of the table circle below in lines dvergng IRON
its original line OF due north and SOUTH towards the rad
running eastward on the aide and westward the
other side Of the circular table. But this new motion
the penduuns only apparent notion relative north
and SOUTH or the cardinal points of the earth lis ALSO
lutte motion IN regard 10 innue spaes the pendulum
commenced-1rom north to southland pios versa for
while the pendulum actually moves uniformly il be-
gam the place above, the table below and every
thing connected with the earth that round, leav-
ing the pendulum vibrating on Its original line, north
and south, relative to infinite space.
II Twas thus by This admirable contrivance OF 'Fou-
cault OF in venting pendulum entirely free from the dis
turbng iphn OF the eartbs notions that he able
to furnish oc 1lat demonstration of the rotation OF the
earth on its or bit