The Hawaiian gazette., 1905-11-10

I as the geographical poles do. but move
around more or less. Just how or why
is not known either. One of the minor
objects OF the present expedition. which
has Planned for It and its successors a
twenty-year job. is to throw some light
| on these unknown matters.
| But the expedition is under the con-
| troll OF the Carnegie Institution OF
Washington, d. c., and though the in
stitution has an endowment of 10000
900. its work is strictly limited to prac-
tical subjects. Therefore, the present
expedition is cQnfning itself to locating
these magnetic lines.
| The practical side of IL comes in
from the fact that the needle of the
compass, which is, Of course, itself very
sensitive to magnetic influence and
points approximately TO the geograph-
ical north and south poles. as a matter
| of fact points toward the north and
| south magnetic poles, so that every
| map shows the true north and the
variation" toward the magnetic north
| pole. Such a variation might throw
| the navigator very far off his course
| unless it Is actually known and allow
ance Is made for ii. 1t is perfectly
possible to absolutely determine the
| variation on land, but on the sea the
ordinary ship has to rely on tables
compiled from the experience of navi-
gators of all nations internationally
| exchanged, and the observations made
OF land all over the world.
| Some of the old wooden ships heav-
lily coppered have made very valuable
observations at sea. but the modern
steel or iron ship, often with iron masts
and iron trimmings everywhere replac-
ing the old brass and copper, some-
times carrying, in addition to the iron
| and steel engines and boilers, heavy
cargoes of iron, and having their iron
| sometimes in one part of the ship and
sometimes in another, produce a 'lo-
caP' attraction for the needle which
| largely spoils the value of observa-
tions made upon them from a strictly
scientific standpoint.
| In addition to the fact that the
magnetic poles are not located at the
| geographical poles of the earth, there
is the attraction of the earth itself for
the needle, which causes one end of it
to be pulled down more than the other.
This is called the dip of the needle.
This is as erratic as the first magnetic
element. But in addition to that is the
intensity of the magnetic forces causing
both the variation and the dip"
All these must be taken into consid-
Grafton, as they all defect, more or
less. the needle from its proper posi-
tion, which should point true north and
true south.
The present expedition may then be
described as one to take observations
at sea as to the variation, dip and in
tensity of the magnetism of the earth
for the very practical purpose of en-
abling the navigators OF our ships to
be able to tell exactly Ito within less
than statute mile in any direction)
where their ship is at any moment of
the day they care to make the proper
calculation, no matter how many
thousand miles from land they may
be.
The present maps have been drawn
from observations taken at land points
with absolute Instruments. Instru-
ments that are turned upside down
and the other end to and tested and
corrected under all the conditions in
any way effecting their reliability and
the average or mean result used. But
the lines which cross the seas have
been drawn, though partly from OBJ
servations of wooden ships with nom
magnetic cargoes and fittings, largely
from estimates made by scientists
computing conditions at sea from a
point on the land several thousand
, miles away possibly.
1t speaks highly for the accuracy OF
modern science and equally highly fol-
the modesty and candor of the officers
, OF this expedition that there be chron-
icled the fact that not to exceed two
degrees of error in the present charts
has been observed by the Galilee dur
ing her five weeks cruise which in
cluded over fifty separate and dis
tinct observations.
The ship was probably navigated as
CLOSELY" that is to say with the most
accurate and finely drawn computa'
tions as to longitude and latitude OF
any ship that ever sailed the seas un
der any flag in the entire history OF
the world. Her people are scientists
and they wanted to absolutely know
where they were to within the small
est fraction of a mile, so that wher
their delicate instruments were set t.
, work and recorded definite result
they could say positively at exactl,
a what longitude and latitude they OBJ
, served a given condition.
Z The Galilee's company went from
here to Tanning Island, leaving her
e on the twenty-eighth of September AM
v arriving at Tanning the eleventh o
October. Leaving there on the four
e teenth, they proceeded south, crossing
r the geographical equator and, ninet
: miles further south they crossed tn
e magnetic equator at which point ther
$ is no dip to the needle OF the com
pass. Not very far west of where the
y crossed the equators, these two equa
Il tors cross each other, the magneti
e equator being north of the geographica
e equator in Asia and south of it 4
o America. In the central part of Sout
America it takes great dip to tn
1t south like clothes line blowing /
the wind. The magnetic lines whic
in same places are almost exactl
parallel to 1t dn the same manner a
parallels of latitude are parallel to til
equator) in other places seem to ru