Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1889-12-23
SAILING THE CIRCLE.
COMPARATIVE PERFECTION or THE
ART OF NAVIGATION.

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The arr Of navigating ships seros s.as and
oceans from the port Of one country 70 that
of another Il one Of which The world In gen
srai oatzide the nautical and hydrogrsphical
profs.ious known little or nothing. and yet to
The progress and comparative perfection
which have been achieved IN ie are largely
due the extent and success Of the vast com
u,erce between the natious Of the earth,
which make OF the oceans great intsrnsr
taonai highways over which are carried tbs
products Of all ciimss TO all other china
The Older maritime nations that propelisd
their vessels with oars and had only the sun
BY dsy and stars by night 70 guide them.
rarely sfssred their salleys far from land,
but Rugged the shore. The introduction Of
the mariners compass TO Europsan nations.
about go years ago-though the Chinese
claim to have used It hundreds Of years earh-
r-and the substitution Of sails for carr,
made it uracticabls TO strike out boldly into
b. sure, to the alterations from the existence
Of ocean currents and the occurrence Of
hesd windA 1t was the mariners compass
that enabled Columbus to steer westward
from Spain and discover the American con
tinent
MERcAroR's CHART
For some time after the introduction Of
the mariners compass navigation was still
verv imperfect, in consequence Of the mac
curaciss OF the plane chart. which was the
only one then known, and not much was
done until the publication Of Msrcator's
chart, which greatly altered former theories
on the subject Of navigating the ocean The
method Of constructing charts on Mercator's
projection depends upon the development Of
. cylindrical surface, by which means they
have the parallels Of latitude and circles Of
longitude respectively represented by paral-
lei straight lines But while this was .
great Improvement over former charts, and
is the chart in common use today. until quite
recently II could not be depended upon by
the mariner to shape . course by the shortest
route betwssn two distant points without in
volving extensive mathematical calculations
on his part For the present purpose. then,
it may be said that the first thing the uavi-
making his offing, a. 1t is terinsd-that H.
getting clear of lands TO shape his course'
TO the point Of destination or to some land
mark on the coast near TO it. He looks over
his chart To see il there are shoals or rocks or
other dangerous places, and il there be he di-
reefs his course primarily so - to avoid
them; IL not, the difference In latitude and
longitude between the two ports being taken,
tha a,,j k..< obi H.
the aid Of trigonometry.
The shortest way TO any two places on the
face of the globe is not found by following .
line upon ordinary Mercator charts drawn
between those places. 1t is found on the line
of the arc Of the great circle, 50 called, which
on an ordinary chart would form a curved
line, the arch Of which would incline north
ward at the north side Of the equator and
southwark to the south Of 1t. What is termed
the terrestrial meridian is the great circle
formed by the intersection Of the surface Of
the earth by the plane passing through the
poles and the spot on which the spectator
may ne standing, and the first meridian is
the meridian from which longitudes are reck
oned
wcl.sIst OCT A GREAT CIRCLE ROCrE.
NON. tie idea Of great circle sailing is to
points between which long expanses Of yea or
ocean intervene. Heretofore it has been .
very serious matter 10 work out great cir
Gle route, for the reason that it was necessary
to go through great number of mathemat-
zeal c,ituiatious in order TO obtain the vari-
oil, points for the processes OF the route On
an ordinary chart, as already said, a great
circle Inc would appear as a curve, Sup
IN i.a sbrr nod ha
Gram. banks Of Newfoundland TO Cape Clear,
on the west coast Of Ireland. Let a straight
line be drawn on the map for the course II
this were followed, the distance sailed be-
tween the two points would be much longer
than II sailed on the line Of the great circle,
going considerably south of the latter This
is the fault Of the method by which the chart
has been projected.
To give an illustration Of how line over .
convex surface may be . straight one, as well
as straight line over plane surface may
be convex one, as shown, it may be stated
that if the spectator were placed at the cen
ter Of the earth, every great circle on its sur
face is bound TO cut his eye, and will conse-
quently appear to him as perfectly straight
lines. whereas, in fact. they are really curved,
and the amount Of their curvature varies &C
corling I" the distance from the equator
On the equator or on the meridian the
shi or Mercator track will coincide with
the great ci;,.. track, and the course In
either cas4 y .ui h. ,st OF west, north or
south. 1t fo Tvs f. this condition Of
things that, ii char ould be obtained that
was projects IN plane sur ace, on which
the lin wer laced IN the exact positions
In viii =; the Gould b, seen hv ar observer
or no, tor Il the .Hf1 W stlputf hAvo q