Barton County democrat. [volume] (Great Bend, Kan.) 1885-1915, 1900-03-23
NAVIGATION ON THE SEA.
How the Rig Ships Are Guided on
Their Way Across the Track
less Ocean.

Any one who has ever been q paSsen-
ger ona great transatlantic liner OF to-
day knows what an important, impos-
ing perscnage is the brass-bound skip
per. A very 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 deep, delightful mystery. He it is
who ''takes the sun" at noon, and finds
out the ships path at sea. And. in
truth, regarded merely as a scientific
experiment, the guiding of q vessel
across the unmarked, trackless ocean
has few equals within the whole range
of human knowledge. 1t is the pur-
pose of this brief article to explain the
manner in which this seeming impossi-
billy is accomplished. We shall not
be able to go sufficiently 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 it
self. 1t is nothing but an instrument
with which we can measure how high
up the sun is in the sky. Now, every
one knows that the sun slowly climbs
the sky in the morning, reaches its
greatest height at noon, and then
slowly sinks again in the afternoon.
The captain simply begins to watch
the sun through the sextant shortly
before noon, and keeps at it until he
discovers that the sun is just begin
ming to descend. That is the instant
of noon on the ship. The captain
quickly glances at the chronometer.
or calls out moon" to an officer who is
near that instrument. And so the err
ror of the chronometer becomes
known then and there without any fur
Their 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 mys
terious chart room" some printed as
Economical tables, which tell him in
what terrestrial latitude the sun viii
have precisely that height on that par
ticular day of the year. Thus the ter
restria1 latitude becomes known easily
enough, and if only the captain could
get his longitude, too, he would know
just where his ship was that day at
noon.
We have seen that the sextant OBJ
servations furnish the error of the
at noon. In other words. the captain
is in possession of the correct local
time in the place where the ship actual
" SC he ole ho6 he Of
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, it will be much too
fast on arriving at Chicago or San
Francisco; the farther you go the larg-
er becomes the error of your watch.
In fact. if you could find out how much
your watch had gone into error, you
| would in a sense know how far east or
| west you had travelled.
Now, the captains thermometer is
set to correct Greenwich time on
shore before the ship leaves port. His
observations having then told him how
much this is wrong on that particular
day, and in that particular spot where
| the ship is, he knows at 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
tance from Greenwich in an east-and-
west direction, just as latitude is only
| in north-and-southd direction. Green
wich observatory is selected as the be.
! ginning of things for measuring longi-
| tudes, because that worthy monarch
| Charles II. (who seems to have done
one wise thing) established it at n
| date preceding the foundation OF all
other existing astronomical observa-
| tories.
One of the most interesting bits of
! astronomical history was enacted in
| connection with this matter of Iongi-
| tude. From what has been said. it is
clear that tie ships longitude will be
obtained correctly only if the chronom-
eter has kept exact time since the
| departure of the ship from port. Even
a very small error of the chronometeT
will throw out the longitude good
| many miles, and we can understand
| readily that it must be difficult in the
| extreme to construct a mechanical
contrivance capable of keeping exact
time when subjected to the rolling and
| pitching of a vessel at sea.
Tt was as recently as the year 1876
that the first instrument capable of
keeping anything like accurate time
at sea was successfully completed. II
was the work of an English watch
4
one of the few great improvements
| in matters scientific which the world
owes to desire for winning money
| prize. 1t appears that in 1714 a com