Richmond daily times. [volume] (Richmond [Va.]) 1850-1853, 1851-04-28
The Ear1h's Rotation rendered uisible.

/
| BY answering theseState and critical inquiries you
| will very much oblige, yours, respectfully, II.
| The Eartt's Rotation rendered visible.
| Who is there that has not heard men deny
| dong since the days of Galileo) the fact of the
earth's rotation on its axis? We, at least, have
known more than one instance of stubborn incre-
dulity, and, if the truth could be disclosed, we
suspect about half of every civilized community,
to say nothing of the savages, believe, in their
hearts, that there is no reality in what the astro-
nomers say about the matter. Some palpable,
easily ineligible demonstration of the fact is
therefore highly desirable, not merely as con-
tribution to science, but for the purpose of dssi
pating popular error. The last advces from Eu-
rope contain descriptions of remarkably beauti-
full and ingenious experiment, which may now be
seen in Paris, and may actually be said to make
the rotation of the earth visible to the naked eye
We subjoin an account of it, though not perfect
| ly satisfactory one, from London paper, which,
with highly discreditabe jealousy, fails to men
| ton the name of the inventor, who is M Foucat
young French Savant who was, recently, very
near receiving the high honour of being chosen
as the successor of Gay Lassac in the Academy
| of Sciences. If his reputation rested on nothing
beside this experiment, his name would be indeli-
| bly, written on the roll of fame.
| The Paris correspondent Of the National Intel
| ligencer gives translation of NJ Foucau's expo
sition of his experiment, which we have not by
us as we write. 1t may aid the reader however,
to state in addition to the explanations of the Lon
don Globe that the great principle of the pendulum
| in its simple form of ball suspended by a wire
or thread, supposed to be mere line without
weight, is that when the ball is once put in mo-
tion it will vibrate in the plane, in reference
| to absolute space, without respect to any change
of position in the opposite extremity of the wire,
or the point of suspension. If the earth revolves
on its axis once in twenty-four hours, the
point of suspension of such pendulum must, of
course, in that time, describe circle But, if the
ball of pendulum, capable Of vibrating for twenty
hours, moves during that whole period in the same
plane in which it STARTS the revolution of the earth
mast cause the ball to describe at every vibration
over horizontal surface beneath it, slightly
dferentline, until in six hours, its apparent plane
of vibration shall have described quadrant. in
twelve sem-circle, and in twenty four complete
circle NJ Foucat verified this reasoning, by the
extremely simple continuance described in the fol-
lowing article, and by means of which one may
see as direct an effect of the earth's rotation as
the apparent revolution of the sun, but which it is
impossible to explain with that hypothesis.
| from the London Globe, April 81
| The rotnfi0n of the Earth renderph V;sibIe
The experiment now being exhibited in Paris, by
which the diurnal rotation OF the earth is rendered
palpable TO the senses IS one OF the most remarkable
ofthe modern Notifications oftheory Although the de-
monstraion by which the rotation OF the earth has
been established be such to carry conviction to the
minds OF all who are capable OF comprehending it, to
which nothing can be imagined to add either force or
cearness, nevertheless even the natural philosopher
himself cannot regard the present experiment without
feelings Of profound interest and satisfaction and to the
grea. mass. to whom the complicated physica! pheno
mena by which the rotation of the earth has been es-
tsblshed are incomprehensbe, this experiment il in
valuable. At the centre OF the dome OF the Pantheon
fine wire is attached, from which sphere of metal
four or five inches in diameter is suspended
hang near the floor OF the building This apparatus is
put in vibration after the manner of pendulum. Un-
der and concentrcal with it, is placed circular table,
some twenty feet in diameter, the circumference of
which is divided into degrees, minutes, &C. and the d.
visions numbered. Now, it can be shown by the most
elementary principles of mechanics, that supposing the
earth to have the durna motion upon its axis which
is imputed to it, and which explains the phepomena OF
day and night &c, the plane in which this pendu.
lum vibrates will not be effected by this durnal mo-
ton but will maintain strictly the direction dur
ing twenty hours. In this interval. however the
table which the pendulum is suspended will con-
tnuay change its position i'll virtue OF the diurna
ton, so as to make complete revolution round its
centre.
Since then, the table thus revoves. and the pendulum
which vbrates does not revove the consequence
s that line traced upon the table by poiLt projecting
from the bottom OF the ball will change its direction
relatively the table, from minute 10 minute and from
hour to hour, that it such point were pencil and
that espread upon the table, the course formed
by this pencil during twenty-our hours would form
system Of lines radaing from the centre OF the table, and
the lines formed alter the interval OF one hour would
always form angle with each other OF ID deg being
the twenty fourth part OF the circumference. Now this
is rendered actually visible 10 the crowds which daily
flock TO the Pantheon 10 witness his remarkable expe
riment The practised eye OF correct observer espe-
cially if aided by proper optical instrument, may act
ualIy see the motion which the table has, in common
with the earih under the pendulum, between two
cessive vibrations 1t is IN fact apparent that the ball
or rather the point attached TO the bottom OF the ball
does not return precisely the same point VI the cir
cnmerenee Of the table after Two successive vibrations
Thus is rendered visible the motion which the table
has 10 with the earth. It's true that, correct
iy speaking the table does not turn round It's own cen
tre turns round The OF the earth; nevertheless
the effect of the motion relatively to the pendulum sus
pended the oil the table, precisely inc same
as it would be the table moved once IN twenty Tour
hours round its centre, Tor although the table no
turned in common with the surface oil the EARN, fouuu
the eartfs axis the point OF suspension of The Eendu-
lum is turned also 10 the time round tie AXIS
being continually maintained vertical above the centre
OF the table, The plane N which the pendulum ybraes
does not however, parake OF this motion, and, eonse-
quently the appearance OF revolving twenty
four hours the table, while in reality, Is the table
which revoves in twenty-tour hours under il.
| Gen. Scatt arrived at New Orleans on the 23d inst
/ and was oreead on landing with a grand salute,