El Paso herald. (El Paso, Tex.) 1901-1931, 1912-04-20
How the Sextant Is Used by
an Explorer to Ascertain
His Exact Location.

4 BIRD'S-ETE view Of the route
~ taken by Captain Roald Amund-
sen to the South Pole looks like
a mountaineers picture of the way up
to an Alpine summit. 1t was climb.
After marching $50 miles across the
wonderful plain of floating ice. called
the Great Antartic Ice Barrier fro2-
eu floor from SEQ to 1900 feet thick.
w hich floats on the surface OF the
cean-Captain Amundsen encountered
the real edge of the South Polar con-
mountains, buried deep under snow and
ice.
Then he began to climb, and contia-
ued 10 mount higher for DAYS ascend
ing first 1000 feet above the sea; then
400 feet; and finally, after some
slight dips downward, to 10, 500 feet
which was the highest point ne at
tanned. although he saw. aside from
his route. peaks $4,000 feet high.
Great White Way.
The vast white stairway Up TO tho
Polar plateau. the greater part Of
which Amundsen asceuded in four days,
is something over 40 miles long. once
on top OF the immense snow-buried
plain TO which this strange climb led
him. Amundsen found the surface COM
paratiVely Level, as If he had arrived in
the midst Of a lofty prairie where
snow and ice and hummOcks took the
place OF grass and trees. An almost
straiEhtaWay march OF about 80
miles over the level top Of the plateau
brought him 10 the site of the South
pole. which is raised 10000 feet above
the sea.
Across the lofty plain, whose center
is the southern hub OF the earth, fierce
winds blew. charged with Ice particles
as piercing as needles. and Amundsen
cOuntered their greatest difficulties
To the discomfort caused by the
storms vas added the exhaustion aris-
ing from the rarity of the air al an
sea-Ievel But they pressed on, until
on December a, their observations
showed that they had reached the pole.
Always Facing North.
For them east and west and south
itself, had vanished. and turn whatever
way they would they were always
facing north.
Round them the sun, keeping about
p degrees above the horizon CIR
cled continually. neither rising nor
setting and neither getting percep-
tibly higher nor lower in the course
of a hours. When they saw this they
knew that the pole was beneath their
feet But human senses are uncertain
in their action, the atmosphere varies
in its power to bend rays Of light. IN
struments are not perfect and q small
change IN the elevation of the sun, too
slight to be noticed might mean that
from the true pOle-and so, to make
sure. they camped for three days, and
repeated their observations again and
again. and finally marched around the
neighborhOOd Of their camp, covering [
circle OF sufficient diameter TO
make them absolutely confident that
the pole could not lie outside the area
that their feet had trOd.
The instrument on which they prins /
cipslly depended TO ascertain their To- 1
cation was the seXtant. The way 1t is |
used is shown in the picture To I'M I
derstand this II is necessary to. remem- !
Der that the height Of the sun above I
the horizon at noon on any given date I
and at any given latitude may be 4
known from astronomical tables calcu- 1
lated long in advance. AT the poles 4
the latitude is 90 degrees and there. I
during the six months day which pre- i
walls alternately at each pole il is 4
always noon, because throughout the !
course OF "a hours the sun keeps at /
virtually the same elevation.
The sun The Same.
When, then, the explorer finds that
the sun remains at the same elevation,
as measured by his sextant. for "a I
consecutive hours. he knows that he |
must be at one or the other of the |
poles, because nowhere else would the