Omaha daily bee., 1909-11-21

E" we"
an annual term Of variable range in addi-
ton to that Of fourteen months G27 days.;
and with a third ellipse having a period
Of thirteen months; thus nearly accounting
for the irregularities in the polar wander
ing shown on the diagram, not yet OBJ
served at the time Of Chambers classical
papers.
The search was the Fundamental one In
science. for law. With the law discovered.
past observations could be corrected for
vagsries Of latitude, future observations
could allow for It by a formula. Moreover,
better knowledge could be gained Of the
earth, OF its rigidity, its yielding to the
transfer Of matter on its surface, as by
icebergs, ocean currents and winds. The
ormulae SO far proposed are not wholly
adequate: a small term has to be added,
known from its japanese discoverer as the
Kimura effect. 1t can be explained on the
assumption that the center of gravity Of
the earth is not absolutely fixed, but
moves backward and forward a few feet,
five or six, with a period Of a year. This
is, however, not yet to be regarded as es-
tablished.
The human occupation Of the North pole
can not increase the accuracy of the meas
urements, or Enable us to penetrate deeper
into the underlying law Of nature involved;
that work can be done better far away at
the stations in temperate latitudes.
DetermininE Position.
The question is nowadays often raised
as to how, precisely polar travellers can
determine their position, upon which alone
can be based the proofs of their achieve
ments. Not to compare with the accuracy
described above, Of course. The instru-
ments must be very light ard readily port
able; not so delicate as to be liable to de-
r"angement; not SO complicated as to be
difficult in operation. The hand seXtant
is commonly used, although small univer-
sal instruments are made by German
mechanicians, which are about as portable
as a sextant, and capable Of better work.
The sextant is the only instrument which
can be used at sea, for its basic principle
is that it allows the observer to see two
different things at once, the sun, or star,
and the horizon. II he pc nted an instru-
ment first at the star and then at his horl-
zon, the Intervening pitch or roll of his
ship would so alter the angle between the
two points that his observations would be
vitality yitiated. But il he is sk,lful enough,
despite roll and pitch, to hold his sextant
in hand and get the two objects into APP
parent contact in his field of view, then
on the graduated circle (nominally of 60
degrees) he can read the altitude in de-
grees, minutes and seconds. of star or sun
above the horizon, at the moment of that
contact, From his noon altitude he can
deduce his position within a mile or two.
On land the definite sea horizon is lack
ing, and recourse is made to an artificial
horizon, consisting usually Of a shallow
tray Of mercury, protected from ripples
due to wind by a glass cover. The observer
points the little telescope of his sex ant
down obliquely at the mercury, and moves
the arm of the sextant over the gradua-
tons until the image Of the actual sun
is seen in apparent contact with the image
reflected from the mercury. The reading
Of the instrument is then exactly double
the altitude Of the sun above the horizon
tai plane; his pointing at the mercury is
as much below the horizon as the real sun
is above it.
Simple Methods.
At temperatures where mercury freezes.
a piece of plane plete-glass, black, or per-
haps silvered, after being carefully leyeIed
with a spirit level, would lake the place OF
the mercury surface. The altitude of the
sun or bright star should be measurable
'@% - @N@NAN - ~ - uNbAE q, . klNe Ills
latitude within a mile or so, despite cold
and wind. When near the pole a consider
able error in the chronometer would but
slightly affect the measure Of latitude. A
few pages from the 'Nautcal Almanac.
would have to be at hand for the compu-
tation, to give the declinatlon Of sun or
star or its distance north or south of the
celestial equator. On March 2l or Septem-
Der q, when the sun is on the equator. the
suns altitude at noon, subtrac, ed from g.
degrees, would itself be the latitude
sought. At any other date the declInatlon
would have to be added or subtrdcted from
the angle of 30 degrees altitude, according
as the sun was north or south of the euua-
tor. This is because the angular distaps &c
between zenith and celestial equator is The
same as that between observer and the
terrestrial equator, or She latitude.
Tn mariners compass, would. of course.
fail TO point north for any one we'll on in
his journey toward the pole, for it points
toward the magnetic pole, long since DIS
covered In latitude 70 degrees and longitude
81 degrees, or about L5OJ miles north from
Winnipeg. To a traveller I'm north Green
land, the direction indicated by the com
pass would be exactly southwest. but The
usefulness Of that instrument would not
thereby be impaired.
O~bHervRtiOns Of the sun.
Local time and longitude become indefi-
mite at the pole, where all meridians meet.
but conditions are such that, with a clear
sky, the observations of the sun would
very readily prove the exactness Of the ex-
plorer's situation. For instaLce. on April 6,
1903, the sun would make the en.ire circuit
Of the horizon at an altitude Of Ga de,rees
rising % minutes, or two-thlds OF its d.
anleter, higher in twenty-f, ur hours. How
ever erroneous the time Of the wa,cn o.
c~hronometer, two observations six hours
apart should show an Increase OF altitude
OF one-fourth of this, or 5a minutes, and
the same change should occur dur ne the
next six hours, On April p, 1903, the suns
altitude would average just " degrees for
the day, again increasing 20 minutes, or
one-third of a degree, in the following
twenty-four hours.
Thus, even with the simplest Instruments.
the observer should have no difficulty In
establishing his presence at the actual pole
In clear weather. 1t would be done without
] Instruments EnnnnGa that r,a FgF..