Morning herald. [volume] (New York [N.Y.]) 1837-1840, 1837-06-13

| axis between the two poles The north point of the
needle being positive and the north negative, repes
the negative and attracts the positive end and the
south pole of the ring being positive, repes the mega
tive end of needle, and thus demonstrates the above
laws of motion. The position of the needle, thus
pointing due north and south, IS demonstration that
the currents of the electric fluid are IN the line OF It's
direction. BY increasing diminishing the positive
force of the south pole of the rng the needle departs
from due north and south direction, and exhibits
that phenomenon of the marine compass called the
variation of the needle, and thus demonsra es that
equal balance of the negative and positive forces IS
necessary to the correct direction of the needle.
BY moving the compass from the line OF the axis TO
the outside of the ring beginning at the line OF the
EQUATOR and moving round the circle (either north
or south, but say norh the phenomenon of the dip
ping needle is displayed and the error of all geogra-
piers and navgators in supposng that there is mag
netlc pole, las marked upon gobes distinct from the
true north pole is demonstrated The positive end of
the needle begins to dip as it approaches the negative
or north pole until il comes to the goth degree which
is the true pole, when it becomes perpendicular. And
II Captain Ross, or any other person. had reached
that degree, he would have found the needle become
perpendicular and thus have discovered the true mag
netic pole. BY this experiment, we also discover
an nfalble rule for ascertainng the exact latitude
and longitude of any place. by calculating together
the variation and dip of the needle at that place This
problem, so immensely important to navgators has
never been accurately applied, because the true mag
netic pole has never before been discovered, but
the solution of this problem may be proved by rovers-
ing the process and giving the latitude and Longitude
to find the dip and variation.
BY moving the compass midway upon the fiat sur
face of the rng avoid the dip OF the needle; for
the currents from the negative and positive edges of
the ring acting equally upon the positive and mega
tive poles OF the needle, keep It parallel with the line
of direction, and thus shows that the dip of the
needle the edge is occasioned by the greater
attraction between the positive pole of the needle and
the negative pole Of the earth, than between the
gatve pole of the needle and the positive pole of the
earth, when in the northern hemisphere. These two
experiments show that the dip of the needle and the
variation Of the needle, arise from the same cause
and bear ratio to each other that may easily be cal
culated
We have not time, today, to explain the beautiful
and instructive phenomena of ring with four and
eight poles nor those of solid ball of magnetised
Steel which Dr. Sherwood has also made but we
have made ourselves acquainted with all the princ-
pies upon which they depend, and will illustrate them
at an early opportunity We can assure our readers
that if these subjects not the most amusing that
could provide for them, we know Of none more
important interesting than those which we shall
occasionally select from this great philosophical dis
covery, to blend with lighter matter.