New Ulm review. (New Ulm, Brown County, Minn.) 1892-1961, 1899-04-05
e. SERIOU Us PRO BLEM
THE COMPASS AND THE GROWING
USE or ELECTRICITY.

THE COMPASS AND THE GROWING
USE OF ELECTRICITY.
"A Danger That the Magnetic Needle
May he Rendered Practically USE
les. to the Mariner and the Sur
veyor-A Curious Discovery.
Although the invention and introduc-
tion 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 laid on one Of these draw backs to
electric traction in the address delivered
by Professor A. w. Rucker at recent
meeting Of the British Association For
the Advancement Of Science
In various parts Of the world observa-
tories have been established for the pur-
pose of keeping track of the chapges-in
the direction in which the magnetic
needle points. It was long ago discov-
cred rot only that the compass does not
aim directly at the north pole, but that
the amount Of variation in its indiea-
tons from true north undergoes slow
alterations Hence it is necessary to
mako fresh charts, showing the varia-
ton for different parts of the globe
every few years. But in order to get
the data for such corrections-of the
highest Importance to the surveyor and
mariner-it is requisite that careful OBJ
servations be made continuously at q
number of widely separated points
Two of the most famous and hitherto
useful institutions of this class are stu
ated in Washington, in the grounds of
the naval observatory and in Toronto.
The interference of the electric currents
that run through the earth and the
track of trolley lines which have been
constructed near these observatories in
terfere 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.
So delicate are the Influences which
the magnets in such an observatory are
intended to investigate that they can be
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 jackknives,
keys and all other metallic objects about
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 a telescope,
on an adjacent pillar, is used to read
the fluctuations, which are too small to
be discernibie by the unassisted eye. A
tiny mirror, as big as dime, catches a
beam of light more slender than the
lead in pencil and reflects it away to
a 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
sw;4gs 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 it acts. And SO sensitive are
they that their readings are apt to be
interfered with by exceedingly trivia.
causes. 1t is customary for the superin
tendent to inscribe on the scroll "Visit
ors admitted" whenever such a breach
of the regulations is permitted, so thai
if any abnormal fuctuation is detected
in the motion of the magnets suspicion
of it's meaning will be excited in tht
mind of the scientist who afterward ex
amines the Photographic trace.
In spite Of the delicacy of the appa
ratus, it may seem surprising to the la,
mind that the passage Of trolley cur
rents at distance of many rods from
the observatory should be able to affec
the instruments within. But they do
and it is impossible to separate in tn
record the variations produced by genu
inc changes in terrestrial magnetism
from those which are caused by th
trolley. Professor Rucker said few
days ago: "From all. parts of the worl'
we hear of ohservatories ruined O
threatened by the invasion of the cleo
trical engineer. Toronto and Washing
ton have already succumbed, Potsdam
Pare St. Maur, Greenwich and Kew ar
besieged, and the issue largely depend
upon whether these great national oh
servatories can or cannot make goo
their defense. !"
Although the practical service t
mankind which is rendered by institu
lions of this class is alone sufficient
justify their maintenance and to wa,
rant alarm as to their future, there ar
other questions involved which posses
profound interest for the philosophe,
We know that the earth is magnet