The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1892-06-19
THE MAGNETIC POLE.
Its Position to Be Definitely
Fixed by a Survey.
OF THE NEEDLE.
The Achievements Of Former Expedi-
lions and the Feasibility of the
One Now Projected.
Copyright, 1892, BY A. W. Greedy

If there is a grain of truth in the saying
that proverbs are the wisdom of the
multitude embalmed by the wit of a
single man, it is none the less true that to
some familiar distich may be attributed
prevailing misapprehension of the intelli-
gent majority as to some elementary but
scientific subject.
Passing by examples pertaining to other
subjects, one instance relative to the
mariners compass may be recalled in the
familiar line from Poe: "And the touched
needle trembles to the pole" This in turn
is a somewhat ponderous imitation of the
bright, joyous and delicate lines of pre-
decessor, Barton Booth an actor songs
ter, whose name has almost faded out of
the minds of men. One song, indeed re-
mains to this generation, and from it are
those well-known words: 'Trus as the
needle to the pole, or as the dial to the
sum-"
The writer, however, is not by nature an
iconoclast, and so it is only an incidental
object of this paper to dissipate the error
thus fostered by poetic imagination and
bring again the realizing sense that this,
of all things, is practical age. 1t is
rather that the north magnetic pole is to
be- surve eyed, and the public desire at least
to know where the pole is, when was it
discovered. how frequently it has been APP
preached and how is it to be revisited.
There is a point in Arctic America at
which the following magnetic conditions
prevail: First, the various lines of decli-
nation converge; second, the needle points
vertically downward; third, the horizontal
force vanishes and free horizontally
balanced needle will remain pointing in
whatever direction it chances to be
placed. While this point is, strictly
speaking, the pole of verticity yet
it is commonly known as the north
magnetic pole, in contradistinction to the
two centers of maximum magnetic force,
situated, one in Siberia (about latitude 20
degrees north and longitude 115 degrees
east) and the other to the south of Hudson
bay (about so degrees north, 80 degrees
west), the latter being somewhat the
stronger.
This discussion, be it understood, per-
tains more particularly to the magnetic
pole and only incidentally to the centers
OF force, and in order to make these
somewhat technical statements clear to
the non-scientific reader, it is necessary to
enter into brief explanations as to the
effects of terrestrial magnetism on the
compass.
The mariners compass, as is well
known, consists of magnet or magnet
lied needle freely suspended near it's GEN.
ter. 1t usually is a narrow piece of steel
shaped like very elongated lozenge,
taperlng gradually from it's middle to it's
pointed ends, having near its centr con-
cavity by means of which it is easily bal
anced on a pointed support. To empha-
size particular displacing force exerted
on the position of the magnetic needle, it
is necessary first to consider the condition
of the needle prior to its.being magnetized,
that is, when it is bit of plain steel free
from magnetism. Under such conditions
when balanced by its concavity horizon
tally on a point. it remains in the direc-
ton in which it IS placed, no matter
whether it is directed to the north, south,
east 5r west.
AS soon as the needle is magnetized.
however. and is balanced horizon tally as
just described, it will be found that it will
shift its position so as to point in one par
ticular direction, to which it always returns
after displacement. In this fixed position,
where one end points to the magnetic
south. the direction to which the north
end of the needle points is toward the
magnetic pole, and since over the greater
direction is within a few degrees of the d.
rectiOn of the geographical north pole, it
is generally assumed that the needle
always points to the true north. The
point toward which it is actually directed
is commonly known as the north mag
netic: pole" in or near Boothia Felix
Land.
The end of the compass which seeks the
north is known under several different
names. Airy calls the NOTWITHSTANDING end
the red" and the south-seeking end the
"blue," owing to the custom of marking
the north end of the magnet with spot of
red paint. Faraday names the north-seek-
unmarked" Sir William Thompson
calls the NOTWITHSTANDING end the south
pole" and the other the north pole."
from the fact that dissimilar poles attract,
and hence the magnetic pole of the earth
which is situated in the northern hemis-
phere is dssimilar to that end of the mag
netized end of the needle which points to
the north. French writers usually call
the north-seeklng end "anstral' and the
other ''bOreal."
Among the general public of the United
States the north end is known as the
north pole" and the other the south
pole" natural enough designations. but
which are confusing whenever the aues-
ton is treated from a standpoint of the
earth as a magnet. 1t seems most adyis-
able to adopt the terms recommended bv
Maxwell and Jenkins. in their report of
electrical standards to the British assOcia-
ton in 1868, whereby the north-seekino
pole is called the negative" and the other
the ''positive.''
If a non-magnetized needle is suspended
by its middle by long UNFINISHED thread
OF silk, it remains evenly balanced in the
same position IN which we arranged it,
If the needle is magnetzed it imme-
diately changes its position. There are
two directions in which the needle can
and does move; first, it twists or moves
horizontally to right or to left, as has
been already explained, and second. It
tips vertically one end up and the other
down. This vertical motion is also the
result of magnetic force and the needle is
said to take the same direction of terres-
trial magnetic force. The angie which
the dipping needle makes with the hori-
Zontal plane is known as the Dip
Since the magnetic needle as rule does
not point 10 the true north, that is, TO the
geographical north, it is necessary to give
name to the usually existing difference
between the magnetic north and the true
north. 1t is generally known to the sailor
as the variation of the compass but nv
scientific writers it is called the magnetic
declination. The magnetic declination
then is the variation of the magnetic
meridian from the geographical meridian.
and is measured by the angle between the
two meridians and is expressed in degrees
of aZimuth from zero either to the east or
to the west of the true north. When the
magnetic north is west Of the north il is
west declination. and east when the
reverse occurs.