Weekly national intelligencer. [volume] (Washington [D.C.]) 1841-1869, 1851-06-07
COMMUNICATIONS.
GLIMPsEs OF MEN. AND THINGS, AND PLACES

i
4 ...14 NKw Yoax, Jusx 2,>ls5l.
4 Messrs EDrroRs The Inelgencer was to have hears
from me before now, from Somewhere. Well, owini
to circumaances-for we the slaves Of c,cum
stances-I am here today and may be there tomorrow and
as we know not what day may bring FORTH let say
word here. s7 r3tGa t sltss S
The thing which have in my eye this moment Fo
caus grand experiment showing the rotation Of the earth
with which the learned world is now all agog have beer
reading several articles the subject some in the Intsl
gence and in the Boston papers, where they have us
got up the experiment grand SCALE turning Bunker Hill
Monumentino supendous pendulum, or rather pendulum
case. Every body is delighted with the phenomenon and
all eager to understand it, Many have attempted to e1
plain it, Some have presented points Of the laws which
govern the experiment very ceary and few have pre-.
scented the whole thing clear mud lido know that
present the matter any clearer but have medi.ated
upon il full two hours, and please Lot me try. @
The first law Of motion, as laid down BY Newton, is,
evey body persevsres s rest Of uniform mo-
tion in right line, unless is compelled to change that
state by forces impressed thereon Is idle talk about
pendulum in free space" Independent Of gvtaion.
body in free space cannot vbrate swing to and o
have knowledge Of any such law impressed upon
matter now. The pendulum in its very belongs to
gavitation it is gravation which gives existence The
by two antagonist foces-he attraction Of gavtaon draw
steadily the of the earth with certain force
thu fastening at the point Of suspension holding back
with superior force, and combining it within Fixed limit
When we draw up the ball side and let it CO. the
force OF gravity presses and its tendency is obey the first
law OF notion and descend in straight line towards the
centre Of the earth but the fastening at the point
sion confines TO it's limit and compels every instant
change It's direction to move not in straight line
in the arc OF circle The momentum acquired in the de-
scent if there resisting medium and no friction would
just sufficient to carry it the opposite side the
height that from which it descended when the same mo-
ton would be repeated and the same arc Of the circle again
described Thus the earth entirely without notion
the Pendulum under the above conditions would continue
vbrate forever describing the Of the circle and
the rod of the pendulum would forever sbrae in tho
plane Of absolute space Now just what the pendulum
under these simple conditions aays Does and nothing
else whether the earth be in motion rest and whether
the pendulum be at the pole the EQUATOR any other po
son on the eahs surface The pendulum has no relation
any thing but the point of suspension and the eahs centre
Of attraction is confined vbrate between these two
points But with respect the plane in which it vbrates
or the plane in which the rod moves has perfect freedom
The two forces which con6ne the slightest control
over with regard to the plane in which there
the first law Of notion and continues move in the same
plane in which the impulse Of motion first given it, To
this freedom of plane, however, there condition which
not be overlooked The forces between which the
pendulum vbateshe point Of suspension and the
gravaton-must always be in the plane Of vibration But
in whichever Of the infinite number Of planes that may
these two points the pendulum begins to move in that is
free to remain, and thus far obeys the first law Of notion
Asthe pendulum has but simple, uniform motion in all
positions the eah in order 10 understand the phenomena
Of Foucaus experiment it necessary consider the
motion of the pendulum much as the peculiar motion or
motions Of the table platform under the pendulum upon
which the progress Of motion marked Precisely at the
poe this table, considered only conne1on with the EARTH
would have but motiona rotation its centre like
wheel Its axis The tables axis Of rotation would DO idon
teal with the earhs axis Of rotation The sun, then. the
period Of equinox would be always in the horizon. Let
pendulum be placed directly the centre Of the table, and
in whatever direction made vbrae the plane Of vi
bration would coincide with plane Of the earths meridian
Let the ball be drawn in direction opposite to the SUM- and
it will vibrate toward the sun, and will continue, in all
cessive vibrations in the pane vibrating toward the
Let the pemeter edge Of the table toward the
be marked at the Of the vibration The earth
and the table rotate together their axis and the
mark passes from under the vibrating pendulum leaving
swing in its plane toward the SUM- In twenty -four hours
the earth completes duna rotation and the marked side Of
the table round to its starting point where it finds the
pendulum, faithful to the law Of motion, still sautng the
Again let the table be placed precisely the equator and
will have but motion, considered in reference the
earth. But this motion will be entirely different from that
the pole il will not be rotary motion of the perimeter
around its CENTRE but orbit motion. revolution Of the
table, whole, round the earhs centre. Here the North
star will be in the horizon, and may be supposed be
in the eshs axis of rotation extended. Let the pendulum
be placed directly the centre Of the ablehere the plane
Of vibration may coincide with plane Of the eah's
rdan may cut the plane Of the meridian at every pos
sbe angee the ball be drawn in the direction opposite the
North STAR and let the edge Of the table toward the be mark
ed the ball will then vbate directly toward the star, and
directly the mark the tables and the earth rolls on its
axis carrying table and pendulum with it. through day and
through night the pendulum forever swings 10 the star and at
every vibration finds the mark on the table unmoved be-
meath it, But in every other position the earths surface
between the pole and the equator the table has oo distinct
motions; both Of the motions described above It has ro-
tay motion, greater toward the pole and less toward the
equator by which the points in the permster Of the table
move round its centre and il has an orbit motion, greater
toward the equator and less toward the POLE by which the
whole table revolves about the eafhs axis Thus in any Of
these Intermediate positions while the pendulum swings in
fixed plane that the centre Of the table, the marked
Perimee Of the table round that CENTRE passing
nuay under the fixed path Of the pendulum These mo-
lions may readily be perceived by placing small disks to