The semi-weekly messenger. [volume] (Wilmington, N.C.) 1897-1908, 1898-03-29
THE EARTH'S MAGNETISM
How 1T vsries-A HIagnetic Survey 70 This
State Needed-No Accurate Boundary
Lines tits Cost.

Cnapei Hill, n. C., March 70.
Editors Messenger:
The earth's magnetism is one of those
mysterious forces in the world, the ma
ture Of which nobody has been able to
explain to the satisfaction of other peo-
pie, but like other of these mysterious
forces man is making use of it in the
practical affairs of life through the mag
netic compass, the telegraph, the tele-
phone and in many other ways. No ship
ventures upon the sea without having a
magnetic needle as it's guide; no man at
tempts to locate the boundary line of a
state, county, township, or an acre of
land, without calling to his service this
mysterious force of nature manifested
in the compass of the surveyor. Hence
it deserves a careful Investigation.
1t Is We'll known that our little COM
pass needle Which indicates the magnetic
north does not generally point to the
erue north POLE, but usually a little to
sne east or to the west of that point.
Hence, in ordinary surveyors language
we speak OF the compass needle varying
SO many degrees to the east or the west
of the true north. Furthermore it Is well
Known that the amount Of this variation
Thus, in 1887 the following variations are
approximately correct for three different
places in North Carolina: New Bern, l
degree and 54 minutes west; Raleigh, l
degree and IS minutes west; Ashey1Ile.
81 minutes east.
And yet there are places where the
magnetic north agrees exactly with the
true north and south line, and such
would be spoken of as places of no vari-
alton. But these points of no variation
instead Of remaining stationary, are in
North Carolina moving westward. Thus,
New Bern; in 1866 at Raleigh: in 1897
near Asheville. And this, Of course.
means that the amount of variation at
one place in North Carolina instead of
gradually changing Thus, at Raleigh in
1915 the variation of the magnetic line
from the true north was 0 degrees, Al
minutes east. In about 1866, as stated
north were the same, and hence there
was no variation. But in 1887 the mag
netic north moved to the west of the
true north to the extent of 1 degree and
IS minutes.
Though the variations just mentioned
are sufficiently puZzling to give the en-
gineers and land surveyors a considera-
bic amount of trouble. IL the irregulari-
ties named were all that we have to con-
tend with the difficulties could be over
come with some ease, after locating the
true north and south line at a few sta
tons, as at New Bern, Raleigh, Char
lotte, Asheville, etc.
But. unfortunately, If starting on our
southern boundary line we follow the
cOmpa neeuIe across the state OF North
Carolina, we will find that instead of
travelling in a straight line we would
probably make curves of considerable
magnitude in areas of even smaller ex-
tent than one of our counties. So that
instead Of the magnetic north and south
line across the state being a straight
line. it may be quite a crooked one. Con-
~seQuently a magnetic map of North Car
DINA showing the variation of the COM
pass needle in the several counties of the
state could not be unless the
conditions had first been examined in
each of these counties.
That such a magnetic survey should
be made at once no intelligent person
who is familiar with the records Of our
courts and the difficulties of relocating
old boundary lines can doubt for a mo-
ment. The question arises. how can this
be done: how much would it cost. and
can it be done at once. Let me say that
the first thing which ought TO be done
in the making of such a survey is that
in each county seat of the state the true
north and south line should be deter
mined with all possible care and marked
by stone posts. known as meridian posts,
so that at any time engineers and sur
veyors working in that county can go
to this point, test their compasses and
the variation at that time
This, of itself. would eliminate many
OF the troubles that have arisen in con-
nection with the location of the bounda-
~ lines, but this of itself would not be
sufficient in all cases. for the reason
nlculIOllCu dOOkS Z. NIldl lax dl
the county seat would not necessarily in
dictate the amount Of variation in more
distant parts OF the county. Thus, IL at
Raleigh the variation should BEG de-
grees. and in the southwestern corner Of
Wake county this variation might only
be one degree, this difference Of a de-
gree in the variation would. in running
a line one mile long. throw that line out
nearly 100 feet.
But difficulties of this sort can be
largely eliminated. if. after the true
north and south line has been determined
and marked at all the county seats, a
magnetic map is drawn on which are in
dictated all the records thus obtained:
and il after this map is made any special
variation in the magnetic lines are inds-
Gated. special examinations can be made
in that region in order to determine the
character and extent OF these variations.
After his has been one the magnetic
map can then be revised and the location
Of the curved lines, as well as the
straight lines, can be indicated in each
county.
Then. there need only be- made in the