Omaha daily bee., 1899-10-01
SURVEY THE WHOLE EARTH
An Enormous Task in Which Many Govern
ments Will Take Part.
PLANS TO MAKE NAVIGATION sAFtF
Changing Magnetic Meridens ATcct
the Needle of Compnsses-onc
Thousand stations Necessary
in This Country.

To anyone who has ever seen a surveyor
at work measuring a ten-acre field or a city
lot, the statement that the whole earth Is
TO be surveyed will be startling. But the
governments Of the great nation, including
the United States, have undertaken this
mammoth task. It is to be hoped that 1t
can be completed in ten years, although this
is by no means certain.
OF course the survey will not mean any
of the minute measurements necessary In
the work which are ordinarily made by the
common surveyor. But without the great
work which is now under way those minute
measurements would not be very accurate;
and, furthermore, safe navigation at sea
would be out of the question. For the sur
veyor and navigator alike must depend upon
the compass in order to get their directions,
without which they cannot work at all,
and the compass, contrary to the general
idea, does not always point true north.
On any good navigator's chart of the At
iantio ocean, for instance, besides the cur
rent routes and ocean steiner paths, etc,
there are white lines running almost like
curling snakes. The explanatory lettering
says that along this line the compass varia-
tion is so much, another that one that much
and along that one, more or less, as the case
may be. In other words, when a navigator
Ia in that particular part of the world he may
figure that his compass varies the given
amount from pointing true north.
These points of variation are known as
magnetic meridians and they are constantly
talthough slowly changing.
The geographical meridians are stationary
and always run true TO the two geograph-
tcal poles, SO that everybody knows just
where they are, but unless the magnetic
sn nriItnna 49, .n,gzzi located A.. -
graphical meridians are we'll nigh useless
for exact calculations. So great is the
effect OF the magnetic meridians upon the
compass that a ship may appear to be going
In one direction, according to the geo.
graphical meridians, whereas 1t is really
turning in another. Navigators are Obliged
ito make allowances for the changes in their
calculations, for IL they do not they would
be in imminent danger at all times of steer
ding into rocks and reefs, and there would
be no safety in a ship. Surveyors have also
to depend upon the magnetic meridians fol
their lines, and as the meridians change
surveyors lines would follow them and sur
veys would all become tangled IL allowance
was not made for the shiftings.
a Vast Undertaking.
To catch the elusive magnetic meridians
and fix them so that surveyors and navi-
gators may know their precise location and
make their calculations accurately is the
work upon which the officials and the
geodetic and coast survey have embarked
in common with similar officials in almost
every government of importance in the
world, and the entire earth will practically
be surveyed before 1t is completed.
The officials at Washington have been fol
several years preparing for this work. I'm
der the supervision of Charles A. Schott, as
sistant superintendent of the survey, the
most delicate instruments have been made
to register the lightest and slightest mag
netic impressions ON land and sea, and
these instruments have been placed on board
of every vessel Of the coast survey and IN
nearly 200 observatories on land.
The difference between the magnetic mer
idians and the geographical meridians 1.
like that between the magnetic poles ant
the geographical poles. Only a magneti,
needle can follow their convolutions. A
magnetic chart looks like a picture of snake!
squirming over the globe, their heads con,
verging toward a common center, or tn,
magnetic pole. The magnetic poles are sup.
posed to be four in number, two in thu
northern and two in the southern hemi
spheres. and they slowly shift their posi-
tions around the geographical poles, thu
period Of their changes being centuries. Th'
stronger magnetic pole in the northern
hemisphere is located in the vicinity of tn,
mining region at the head of the great lake
and the weaker in Asia. To illustrate thu
manner in which these poles shift their pc
sitions and thus change the location OF thu
magnetic meridians: In 1868 the magueti,
pole was to the north and east Of Paris; |
moved westward until 1914 when 1t attained
its western maximum Of % degrees "a min
ntes. In 1880 it was at SO degrees AZ min
utes west of Greenwich. In 1895 it will pas
rear the meridian west of Paris and thes
It will pass e~asterly until the year 2116
when 1t will be 80 degrees east of Paris
The eastern variation at Paris will decrease
becoming zero in 1857, when the magnetic
pole will return to the meridian Of Paris.
Columbus Found the AgOnic Line.
The line of no variation, technically
known as the agonlc line, is the basis of al
magnetic calculation and as 1t shifts from
place to place allowance has to be made fol
1t in charts and by navigators and survey
ors. This is the line on which the needle
remains true to the magnetic pole. 1t wa!