The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1868-12-31
IMPORTANT SCIENTIFIC INVESTIGATIONS.
Ofaciai Report ON the Variations or the Nag.
netic Needle.


netic Needle.
augusta (Me) correspondence OF the Boston Adver-
,,. tiser, Dec. 2ol sou,,o, :,
The Governor and Council were authorized, Dy re-
solve of the Legislature OF 1866, to appoint COM
missioner to ascertain all available facts IN relation
the state from rs i sele@ent down to the pre-
sent time. In May, 1896, Mr.. Noah Barker, OF Exc
ter Mills, was appointed commissioner to carry out
the provisions OF the resolve. Having been for u
series OF years land agent OF the state aud being an
experienced engineer and surveyor, who mad made
scientific subjects life study, MIR. Barker was pecu-
liarly fitted Tor the work Of the COMMISSION. The re-
suit OF Mr.. Barker's Investigations viii be given
OF tn that body Prior to the So1meacement Of the
United States coast survey but few OF the varla-
tions OF the magnetic needle, as observed IN TINS
State are recorded and owing TO the doubtful char-
actcr OF some OF the earliest OF these OBSERVATIONS,
we are unable TO place implicit reliance upon tnen
As the magnetic force OF the earth Is planetary
force and is confined to no limited locality the COM
missioner has recognized the necessity OF being able
to compare observations which nave been made
from time TO time in places widely remote from each
other; and in his report he has aimed at usefulness
rather than originality. He has given sucn general
rules and directions VIII enable the land surveyor
TO determine the defamation OF the needle Tor HIM
SELL and with the instruments used In ordinary sur
veys. An original table or asimuths Is given, ex-
tending forward to the close OF the present century,
and for every five minutes or latitude within the
limits OF the States also, time tables for the culm
nations elongations Of the North star have been
The commissioner proceeds to give a historical
account OF the magnetic compass and Its variations.
The variation OF the needle from the true north APP
pears to have been discovered by Peregrn. an
Italian philosopher, in 1919; and Columbus, during
his first transatlantic voyage IN 1892 made the start
ling discovery that the needle deviaed IN its direc-
ton from the north pole Of tine d ~ ami vas
had formerly been regarded. The variation OF the
compass has never been fully and satisfactorily ex-
planned by all the researches OF science. About the
middle Of the sixteenth century observations were
made in France and England which fully proved
that the needle pointed eastward OF the true north,
and 1t was found to vary not only from the true
meridian, but TO vary differently In different
places, and that the variation was not $50, STA
In proceeding in either direction, east or west
from the lines OF no VARIATION the declination OF
the needle gradually Increases ana becomes maxi
mum al certain intermediate point between them
On the west of the eastern line the defamation IS
west; ON the east 1t is east. AT Boston the declina
ton is about nine and a half degrees west; in Eng
land it is abOnt twenty-four degrees west In Green
land fifty degrees west; at St. Petersburg SIX de-
greeS west.
The western line of variation now passes through
Cleveland ohio Tor about south twenty-lour ana
still recedng slowly to the vest Az all places lying
to the east OF the line, including the New England
nearly all OF Pennsylvania and the eastern half OF
virginia and North Carolina, the variation Is west
erly-that Is, the north end OF the, needle
points to the west OF due north At all places
lying to the west Of this line, including the
Western and Southern. States, the variation is
easterly-tlat Is the north end Of the needle points
to the east OF due north. This variation Increases
in proportion to the distance OF the place on either
side OF the line Misunderstanding more than
twenty one degrees eastery variation, in Oregon
and ABOUT twenty degrees OF westerly variation IN
the northeastern part of Maine But no annual rate
can be fixed a certain rule FOR the decllnatiOn
OF the needle, as It's motion Is much more rapid in
some years than In Others. The secular anc dur
nal changes OF the needle are noted a. length, as
also the annual change, magnetic storms, auroral
disturbances, local attraction, magnetic dip, magne
tic iorce, the magnetic poles and merldians About
eight O'Clock in the morning the needle Is in
It's most casterly position; from that time
until two O'Clock 1t moves TO the west;
from that time until evening II moves to the east
from eiuht to nine O'CLOCK In the evening until
three in the morning 1t moves west again, after
which 1t returns TO the place from which 1t started,
to be ready for similar oscillations the next day.
The amplitude OF the Oscillation IL greater IN sum
mer than in winter and Is greater In high magnetic
ATTITUDES than II IS near the equator Thus at Cam
bridge June and July 1t Is fifteen minutes Of arc.
and In December and January II Is ten. In cOnse-
line run In the morning cannot be retraced with the
same bearings at noon /; therefore, not merely the
date at which an important survey Ii made should
be recorded, but also the time OF day.
magnetic decllnation and the report closes with
appendix by Edwin Il. Johnson OF Connecticut,
civil engineer and surveyor which throws additional
light on the variations OF the magnetic needle along
term sdue north" used by land surveyors 10 mean
the true north as distinguished from the magnetic
north, or north pointed out by the magnetic
The report VIII pass into the hands OF scientific
surveyors ana engineers Of our own state who Will
have an opportun ty to Judge VI It's merits. While
this interesting subject 1t Is still only the merest
broaching OF an ineXhaus.lble theme. This il the
first Of the kind, we think, ever made In the
United states; hence Mr. Barker In shaping his re-
port, had no precedent or model to go by, bat, like
the explorer and surveyor in the Wilderness ne was
Obliged to strike out and blaze his own lines with
out any pathway ahead. AS preliminary kwox
this report win be sought after by scientific me;r