The Natchitoches enterprise. (Natchitoches, La.) 1888-1965, 1899-01-26
NO. Is
A SERIOUS PROBLEM.
TIE COMPASS and TIE GROWING
USE G ELECTRICITY.

less to the Mariner and the sLr-
Veycr-A Curiaus Discovery.
Although the incent;on aud iutroduo-
tion Of the trolley system CT street rail
ways have been Of iuestimable value to
civilization il has incidentally wrought
some harm here and there Emphasis
was laid Oh one Of these drQwblcbs to
electric traction in the address delivered
by Professor A. W. Rucktr at recent
Meeting of the British Association For
ts..a Alyancetrant q s;cseaee.
IN various partsr Of fha world observa-
tories have been established for the pur-
pcse Of keeping track of the changes III
tie direction i'll which tho magnetic
needle points 1t was long ago dlsCoy-
cred not only that the compass does not
aim directly at the north Ioie Ldt that
the amount Of variation III Its llGiCa-
tions from true north Undgrc0ps slow
alterations Hence it is necessary to
make fresh charts, showing tie yarla-
tiCn for different parts Of the giOLe
every few years. But in order to get
the data for such CorrectiOus-Of the
highest importance to the surveyor ard
mariner-it is requi' ite that caroful Cb-
servations he made continuously at
numter of widely separated points.
Two of the most famous ana hitherto
useful institutions Of this class arc stu
ated in Washington, i'll the grounds Of
the naval observatory and IL l2rCnt0.
The interference of the eleCtricGC:rents
that run through the earth and tho
track Of trolley lines which have been
constructed near these otservatOries in
terfere so much with the behavior CT
the instruments of both places that the
records now obtained are practically
worthless. And the experts are greatly
puzzled hy the problem Of escaping from
this vexatious interruption of their
work.
So delicate are the influences which
the magnets in such an observatory arc
intended to investigate that they can te
perceived Cnly 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 Ja>kkniyes,
keys and all OtAer metallic objects about
their persons before entering tbo apart
ment The magnets, generally bars OF
steel not over six inches long, are Tps ed
above 4 scale that is Cradratcd t1 tie
most minute fractions, aud telescope,
On an adjacent pillar is used tu ,ogd
tle Il. ca, + 53fisa N.1FciI ife 10 s.iiIi 10
be discernibIe by the una SISTED eye A
tiny mirror, Gs big as dime, catches q
beam of light more slender tIan the
lead in q pencil and reflects it away 70
a sheet Of slowly moving Photographic
paper, On which permanent record is
niaGo. The arrangement Of the aDpaIatus
is such that the movement of TIE mag
net Is maguitied many times in the rec
ord. in order TO render the changes paT-
ceptible.
There arc three sets Of irstrrmerts
on duty in such Gn observatory Cua
swings bori2Clta3.v, Gaa n.,7.-ar'a
compass. Anut2ag uts 4gauu G.nu.
A third is designed g. .ata.a. q Jua li4-
tensity Of the eartH r:p-'i..is:H. Nat,h
is a separate thing from Tie q es"GlJa
in which it acts And 70 sensitive are
they that their readings are apt 10 he
interferGd with by exceedingly trivial
causes 1t is customary for tIo superin-
tenGent to inscribe on the scroll "Visit-
ors admitted, " whenever such breach.
of the regulations is permitted. so that
if any abnormal fluctuation is detected
in the motion Of the magnets a suspicion
Of its meaning will lie excited in the
mind of the scientist who afterward ex-
anires the Photographic trace.
In spite Of the delicacy Of the appa-f
ratus. it may seem surprising to the lay
mind that the passage Of trolley cur
rents at distance of many rods from
the observatory should Ee able to affect
the instrum nts within But they do,
and it is impossible to separate in the
record the variations produced by eenu-
inc changes in terrestrial magnetism
from those which are caused by the
trolley Professor Rucker said few
days ago: From all parts Of the world
we hear Of Obserat0ries ruined or
threatened by the invasion Of the cleo
trical engineer Toronto and Washing
ton have aIready succumbed, PotsGam.
Pare St. Maur, Greenwich and Kew are
besieged, AID the issle largely depends
upon whether these great national OBJ.
servatories can or cannot make good
their defense.
Although the practical service to
mankind which is rendered by institu.
tiOus Of this class il 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 the philosopher
We know that the sarth is a magnet
but as yet no one is able to say what
makes 1t SO The fundamental secret of
terrestrial magnetism has not been
solved. Then, tCo. the-c are various
changes i'll direction which mark the
behavior Of the needle that remain to
be explained What influence is it that
makes the needle swing 10 and fro to
extent every day! Why is it
that the diurnal swing is greater in
years Of sun spot abundance than at the
minimum stage Of solar activity: WY
do the indications Of the needle differ
in summer tIom those of winter? What
is the key to the mystery Of the long
period movement that males it ueces-
sary to rechaTt the situation! What
causes the convulsive behavior Of the
for few hours or days when
there il great outbreak Of sun spots?
And is there any relation between the
weather aud the fluctuations in the
sarth's magnetism? There are theories
IN these sui cts, but no generally &C