Evening star. [volume] (Washington, D.C.) 1854-1972, 1889-08-03

host Of foes, lurking on all sides, working
through remarkable distances and hiding be-
hind all sorts Of substances. There are three
kinds Of deviations, the semi-circular, the heel
ing and the quadrantal. The first is due
to the influences exerted on the com
pass in = horizontal plane, affecting every
point, and to remedy this evil the
little magnets are stuck into the
caused by the fact that when a ship heels or
turns on the waves the compass, being always
level, is brought nearer than ordinary on one
side or the other to some Of the metals in the
vessel. This is compensated by q magnet sus-
pended IN well in the pinnacle under the COM
means Of which it can be pulled up or down.
The heeling deviation of q compass varies with
the latitude. The third cause of deviation,
the quadrantal, comes from the soft iron in the
ship and affects only the four points known as
the "quadrantals," northeast, southeast, north
west and southwest. To overcome this infiu-
ence great balls of soft iron are placed on arms
extending out from either side Of the pinnacle,
30 arranged that they can be adjusted at the
proper distances
FITTING A VESSEL WITH HER CoMpAssEs.
When ship is all ready for sea, every bolt
driven, all her guns ON board, her anchors and
chains in place, Lieut.. Scheutze and his assist
ant go aboard armed with theodolite, dip
ping needle, and a sort Of small cardless COM
pass, wherewith they take all sorts of observa-
tions on all parts of the ship. By means of
their figures they calculate the forces and the
deviations, and them according to carefully
devised tables, they make their compensations
and the compass is ip shape for cruise. There
is often some change necessary in the tables
Of compass, owing to the settling Of mate
rails, but in a comparatively short time the
instrument is perfectly steady in its readings.
EVERY LARGE MAN-oF-wAR
carries about twelve compasses, and the opera
ton Of locating and compromising these is no
small undertaking. Some, however, are little
boat compasses that require no manipulation
There are two steering compasses and one
standard, and sometimes other binnacles that
require compensation. Then there is q tell
tale, an inverted compass that is placed on the
roof Of the captains cabin to show him which
way the ship is steering.
Sometimes it is found that the influences
cease at certain point above the deck of the
ship, and then the compass is raised on a
standard. Some one has even suggested that
the instrument be placed on a mast head clear
Of all interference from neighboring metals. but
so far as is known this idea has never been
adopted.
FIELD OF STUDY.
While working at the Office Lieut.. scheutze
is enabled by means of the wooden model
moving on the brass circle, which is
Cdiicu VIC OCorcSUys dlttT u uOteQ mag
netician, to reproduce most Of the con-
dltions OF the ship, and can thus conduct valu-
able experiments looking to perfection of the
laws of magnetic deviation. Every ships navi-
gator is obliged to make an annual report as to
the condition of his compasses. besides another
report whenever the vessel changes her lati-
tude materially. There is quite a system Of
blanks and reports in use in connection with
the steering guides of ship, so that the su-
perintendent of compasses here is enabled to
study the actions Of every instrument in the
service.
THE MAGNETS
used are composed of small steel wires tied
into bundles. These are magnetized by being
passed into a dynamo in motion. They are
bundled according to weight and labeled by
numbers, being registered at the Office here
They are then returned to the factory in Bos.
ton, where they are put into the compasses
designated by the superintendent.
Thus is the modern sea-going vessel pro.
vided against one of the most terrible dangers
Of the deep, that of going astray. Without thii
process the new navy would be valuable only
for strict defense Of the coast, but with the
power to go to sea without fear of her com
passes becoming 'crazy," she can deal bel
blows thousand miles from home, sweep the
ocean of its traffic, and do incalculable damage
1t is the work of these officers in the Nav
department that brings about the antithesis O
the helpless condition of things expressed by
the witch in Macbeth when she croons over he!
kettle that she saw
"a ship without O sail
And q rat without tail"