The morning news. [volume] (Savannah, Ga.) 1887-1900, 1900-02-25
NAVIGATION ON THE SEA.
How ships Find Their Way Across
the TrackIess Ocean.


Any one who has ever been a passenger
on great transatlantic liner OF to-day
knows what an important. imposing per
sonage is the brass bound skipper Avery
different creature is he on the deck of his
ship from the modest seafaring man we
meet on land, clad for the time being in
his shore going toys. But the captains
dignity is not all brass buttons and gold
braid. He has behind him the powerful
support Of a deep, delightful mystery He
1t is who takes the sun" at noon. and
finds out the ships path at sea. And, in
truth, regarded merely as a scientific ex-
pertinent, the guiding of a vessel across
the unmarked, trackless ocean has few
equals within the whole range Of human
knowledge. / is the purpose OF this brief
article to explain the manner in which
this seeming impossibility is accomplish
fd. We shall not be able to go sufficient
ly into details to enable him who reads to
run and navigate a magnificent steamer.
But we hope to diminish somewhat that
part of the captains vast dignity which
depends upon his mysterious operations
with the seXtant..
To begin, then, with the sextant itself
1T is nothing but an instrument with
sun Is in the sky. Now. every one knows
that the sun slowly climbs the sky in the
morning, reaches its greatest hight at
noon, and then slowly sinks again in the
afternoon. The captain simply begins to
watch the sun through the seXtant short
~ before noon, and keeps at it until he
discovers that the sun is just beginning
to descend That is the instant of noon
on the ship. The captain quickly chances
at the chronometer or calls out moon"
TO an othcer who is near that instrument
And so the error Of the chronometer be-
comes known then and there without any
further astronomical calculations what
ever
incidentally, the captain also notes with
the seXtant how high the sun was in the
sky at noon. He has in his mysterious
chart room some printed astronomical
tables, which tell nim in what terrestrial
lautudc the sun viii have precisely that
hight on that particular day of the year.
Thus the terrestrial latitude becomes
known easily enough, and If only the cap
tain could get his longitude, too, he would
know just where his ship was that day at
noon.
We have seen that the sextant observa-
tons furnish the error of the chrouometer
according 10 ships time at noon In other
words, the captain is in possession OF the
correct local time in the place where the
SNIP dtiudlly Is. NOW, III ne arse DHu the
correct time at that moment of some we'll
known place on shore, he would know the
difference in time between that place on
shore and the ship But every traveller by
land or sea is aware that there are always
differences of time between different
places on the earth. If a watch be right
on leaving New York. for instance, II will
be much too fast on arriving at Chicago,
or San Francisco; the farther you go the
larger becomes the error OF your watch.
In fact, n you could find out how much
your watch had gone into error, you would
in sense know how far east OF west
you had travelled
Now, the captains chronometer is set 20
correct Greenwich time" on shore before
the ship leaves port. His observations hav-
ing then told him how much this is wrong
on that particiar day, and in that partic-
usar spot where the ship is, he knows 1t
once just how far he has Travelled east or
west from Greenwich. In other words, he
knows his Longitude from Greenwich. -
for longitude is nothing more than dis
lance from Greenwich in an east-andwest
direction, just at latitude is only distance
from the equator measured in a north-and-
south direction. Greenwich observatory Is
selected as the beginning of things for
measuring longitude, because that worthy
monarch Charles II (who seems to have
done one wise thing established 1t at a
date prec the foundation of all other
existing astronomical observatories.
One of the most interesting bits OF as
Economical history was enacted in connec-
ton with this matter of longitude. From
what has been said, 1t Is clear that the
ships longitude will be obtained correct
" only if the chronometer had kept ex-
act time since the departure of the ship
from port. Even a very small error of
the chronometer Will throw out the longt-
tude a good many miles and we can I'M
derstand readily that 1t must be difficult
in the extreme to construct mechanical
continuance capable of keeping exact time
when subjected TO the rolling and pitch
| ing of a vessel at sea.
II was as recently as the year 1876 that
the first instrument capable of keeping
anything like accurate time at sea was
successfully completed. 1t was the work
of an English matchmaker named John
Harrison. and is one of the few great Inn
provements in matters scientific which
the world owes TO a desire for winning
a money prize. 1t appears that In TIA
committee was appointed by the House
of Commons, with no less person than
Sir Isaac Newton himself one OF its
members to consider the desira bility of
offering governmental encouragement for
the invention of some means of finding
the longitude at sea. Finally the British
government offered a reward Of $4,000 for
an instrument winch WOulu Ilnn tHt lOuSl-
tude within sixty miles; $4,000 if within
forty miles and 100000 II within thirty
miles. Harrisons chronometer was fin
ished in 1886. but he did not receive the
final payment of his prize until 1854
We have not space to enter into an ac-
count of the vexatious delays and official
procedures to which he was forced TO sub
NIT during those twenty-eight long years.
1t Is matter of satisfaction that Harri-
son lived to receive the money which he
had so thoroughly earned. He had the
genius TO plan and master intricate me-
chanical details, but perhaps he lacked in
some degree the ability of tongue and pen
to bring them home to others. This may
be the reason he Is so little known, though
1t was his fortune to contribute so large
and essential q part to the perfection of
modern navigation. Let us hope this brief
mention may serve to recall his memory
from oblivion even for a fleeing moment;
that we may not have written in vain
of that longitude TO which his life was