Smyrna times., 1898-12-28
SMYRNA, DEL WEDNESDAY AFTERNOON DECEMRFR % 70oo
A SERIOUS PROBLEM,
THE COMPASS AND THE GROWING
USE OF ELECTRICITY.

USE OF ELECTRICITY.
A Danger That the Magnetic NeedIa
May BE Rendered Practically Use
less to the Mariner and the Sur
VeyOr-A Curious Discovery.
Although the invention and introduc-
tlon OF the trolley system of street rail
ways have been Of inestimable value to
civilization it has incidentally wrought
some harm here and there. Emphasis
was lald on one of these draw backs to
electrlc traction in the address delivered
by Professor A. W Ruoker at a recent
meeting of the British Association For
the Advancement of Science.
In various parts of the world observa-
tories nave been established for the mr.
pose OF keeping track of the changes in
Gne direction in which the magnetic
needle points 1t was long ago discov.
cred not only that the compass does NOT
aim directly at the north pole but that
tne amount OF variation in its indica-
lions from true north undergoes slow
alterations Hence it is necessary to
mako fresh charts, showing the varia-
tlon Tor different parts of the globe
every few years. But in order to get
the data for such cOrrectiOns-of the
nlghest Importance to the surveyor and
marlner-it is requisite that careful oh.
servatlons be made continuously at a
number of widely separated points.
Two of the most famous and hitherto
useful institutions of this class are situ.
ated IN Washington, in the grounds of
the naval observatory and in Toronto
Inc interference of the electric currents
that run through the earth and the
track of trolley lines which have been
constructed near these observatories in
tertere so much with the behavior Of
the instruments of both places that the
records now obtained are practically
worthless And the experts are greatly
puzzled by the problem of escaping from
THIS vexatious interruption of their
work
30 delicate are the influences which
the magnets in such an observatory are
intended to investigate that thev can re
perceived only when the apparatus is
most scrupulously guarded The room
In which they are mounted is under.
ground. Visitors are never admitted ex-
cept under unusual circumstances and
are required to deposit their iackknives
keys and all other metallic objects abont
their persons before entering the apart-
ment. The magnets, generally bars of
steel not over six inches long, are poised /
above scale that is graduated to the .
most minute fractions, and telescone
ON an adjacent pillar, is used to read
the fluctuations, which are too small to
be dlscernible by the unassisted eve A
tiny mirror, as big as q dime. catches n
beam of light more slender than the
lead IN pencil and reflects it awav IN
sheet of slowly moving Photographic
paper, on which permanent record is
made The arrangement of the apparatus
is such that the movement of the mag
net is magnified many times in the rec.
ord, IN order to render the changes per.
ceptible
There are three sets of Instruments
on duty in such an observatory One
swings horizontally, like a mariners
compass Another dips up and down.
A third is designed to measure the in
tensity of the earth's magnetism, which
is separate thing from the direction
IN which 1t acts. And so sensitive are
they that their readings are apt to be
lnterfered with by exceedingly trivial
causes. 1t is customary for the superin.
tendent to inscribe on the scroll "Visit-
ors admitted, whenever such breach
OF the regulations is permitted, so that
II any abnormal fluctuation is detected
in the motion of the magnets suspicion
of its meaning will be excited in the
mind of the scientist who afterward ex-
amines the Photographic trace.
In spite of the delicaoy of the appa-
ratus, 1t may seem surprising to the Iay
mind that the passage of trolley cur
rents at distance of many rods from
the observatory should be able to affect
the instruments within But they do.
and it is impossible to separate in the
record the variations produced by genu.
Inc changes in terrestrial magnetism
from those which are caused by the
trolley. Professor Rucker said a few
days ago: From all parts of the world
we hear of observatories ruined or
threatened by the invasion of the cleo.
trical engineer Toronto and Washing
ton have already succumbed, Potsdam.
Pare St Maur, Greenwich and Kew are
besleged, and the issue largely depends
upon whether these great national OBJ.
servatorles can or cannot make good ;
their defense. -
Although the practical service to
which is rendered by institu- 8
tloDs OF this class is alone sufficient to
justify their maintenance and to war ,
rant alarm as to their future, there are ,
other questions involved which possess ,
profound interest for toe philosopher.
We know that the earth is q magnet.
but as yet no one is able to say what
makes it SO The fundamental secret of !
terrestrial magnetism has not been !
solved. Then, too, there are various {
changes In direction which mark the
behavior of the needle that remain to
be explained What influence is it that
makes the needle swing to and fro to
extent every day? Why is it q
That the dlurnal swing is greater in C
years OF sun spot abundance than at the C
minimum stage of solar activity? Why il
10 the indications of the needle differ
N summer from those of winter? What il
IS the key to the mystery of the long b
period movement that makes it neces- \
ary to rechart the situation! What e.
'auses the cOnvulsive behavior of the il
magnets for few hours or days when il
here is great outbreak of sun spots?
And is there any relation between the
weather. and the fluctuations in the
arth's magnetism! There are theories "
N these subjects, but no generally ac- y
epted doctrines. and the human mind
s so constituted that it will not rest Il
Until further light is obtained New fl
FORK Tribune