Evening star., 1922-10-22

and why-a knowledge which is of
| inestimable value to man.
This point in the northern hemi-
| sphere toward which the compass
needle does point is known as the
north magnetic pole. The precise To-
cation of this attractive spot no one
knew until the return of Capt. John
Ross in 1884 from his five years in the
arctic. when he announced its discov-
cry by his nephew, James Clark Ross.
! second In command. in latitude 70 de-
gree 3 minutes ard l. seconds
longitude 96 degrees 46 minutes and
/ 45 seconds W 1t is very doubtful il
such point can be SO accurately To-
Gated, as there are strong reasons for
believing today that it is not a point
but an area possibly fifty miles in
diameter, roughly. at the above loca-
tion and approximately 1900 miles
south of the geographical north pole,
which Peary reached on April 6. 1909
The question naturally arises. Upon
what does the mariner depend for
guidance after he has sailed beyond
! this point?' Upon his compass as
formerly. which persistently points
toward the magnetic pole If free from
local attraction. II the captain of the
! ship knows the extent to which his
compass needle varies from the true of
geographical north. his compass is
fully as valuable to him as II it
pointed due north. If he sailed north
ward 10 Eta. -. .s:!,:Id thence ira
eled westward with dog team, as we
did In 1916. he would reach a point
where his compass needle pointed
south. At that time. if our objective
point was south. we travelled north by
! compass; If west, We travelled east.
THIS difference in direction Of the
i compass needle between true
north and magnetic north is termed
declination or variation, and the force
which causes it TO swing in ho.j
zontal plane is known as the hori-
zontal intensity. This not only varies
constantly with succeeding years in
each locality. but may even from hour
TO hour vary in the same locality.
At the magnetic equator (not CO.
| incident with the geographical equa-
tor but eQuidistant between the north
and south magnetic poles) the needle
assumes horizontal position. This
force, however, decreases in intensity
as either magnetic pole is approached.
and when within a certain range dis
appears entirely. The compass card
| or needle has no directive force what
ever and becomes useless.
AS one proceeds northward or
southwark from the magnetic equa-
| fnr bar cd ba
intensity, manifests itself and be-
comes increasingly stronger with the
distance travelled. This vertical in
tensity tends to pull the northern end
of the needle downward toward the
center of the earth. This angle of
| inclination between the horizontal
| and the vertical is termed the dip.
which is o at the magnetic equator
and 80 degrees at and roughly within
| fifty miles of the magnetic poles The
intensity of this force also varies from
day to day and even from hour, to
hour. possibly due to circulation
between the magnetic intensity of the
earth as giant magnet and so-called
electrical storms and frequency of the
| aurora.
At Boston at the present time the
variation is Is degrees / minute west
erly, and is increasing minutes an
| nually, an indication that the north
magnetic pole is slowly changing its
position westward. At London in 1880
the compass needle pointed 11A de-
grees east of north; in 1884 only
degrees east of north: in 1868 true
north and south: in 1912 20 degrees
west Of north; in 1914 16 degrees west
of north.
On Sunday, September 10. we started
our meteorological observations. Our
lowest temperature occurred on Feb
ruary 10. On that date our minimum
thermometer read so degrees Fahren-
field recorded Sc degrees Fahrenheit
February was our coolest month. with
| q mean temperature of -ss.s degrees
Fahrenheit.
This comparatively warm tempera-
tuFe was undoubtedly due to our
proximity to the open water of the
swirling tides of Fox channel, ever
radiating its heat of plus % degrees
Fahrenheit to the surrounding AT
mosphere and condensing into a heavy
black vapor, which rolled continu-
ously across the Sky for days and
days.
On September % ice began to form
on the ground, driving the young red
| throated looms and old squaws out
into the harbor. Ravens were plenti-
full. as were the white and gray gyr.
-(,--T = 1,-.,