The daily union. [volume] (Washington [D.C.]) 1845-1857, 1846-11-19

west VARIATION when heading from northwest around
10 southwes aud when brought 70 head southeast,
the ten degrees west ysrianon changed 10 three and
half degrees yaraonI this increased 10 seven
and a half degrees east variation, when heading
east, and then gradually decreased 10 the original
two degrees when the heading was again north.
The reason OF these changes Of variation with
change Of heading, is this the compass being IN the
alter part Of the ship, and the being forward
Of the compass mainly when the ship heads north
this and the needle IN the same meridian; bat
when the ships head swings out Of the line, the pow
or is changed to an angle with the needle, asd
draws Il away from tbs meridian in proportion TO It's
power and the angle.
This last difficulty is almost, may say quite in
surmountable in iron vessels by present means
The different pieces of iron Of which they arc com
posed, are constantly changing their magnetic pow
er, 80 rapidly too, that the compass, under the best
arrangements and projections now used, cannot be
depended upon for any given length Of time; even
a few days may make dangerous and fatal change.
10 this, IN my opinion, is referrbe the disaster TO
the Great Britain for, one Of two contingencies COW
ers the cause, (by comparing her published log with
the ehart,) viz; either her eompasses had an error
unknown 10 the captain, she was put ashoreinten
uonally. The last cannot for moment suspect
The first am fully impressed the cause; and so
much so, that ] cannot resist the conviction, al
though have no information as 20 the fact that she
must have laid nearly north and south in Liverpool
passes would not have remeded the evil; for, sup.
pose she was found to have only the known varia-
uoD in that situaton--when she came to head north
west or she did after leaving the Mersey, she mi gh
very likely have had, forward OF her compSsses,
cause sufficient to make ten degrees increased yan
alton. Ten degrees unknown local variation would
have made ten miles Southing in an hundred run;
to this must be added increase which this er-
ror, in her true heading being west Of northwest by
north, her true course and consequently placing the
power still more al an angle TO the needle, inereas
ing the whole sum Of her unknown variation to-
say, twelve degrees. This would have carried her
about ten miles south Of Calf Of Man lights too far to
see them in hazy night. Add to this the proba-
bIhiy that she made greater speed even than was al
lowed in the account Of the affair." and her position
will be accounted for. II must be borne in mind
that when she was hauled up and headed north by
east and north by west, which she did from h. 10
8 h. 80 M, an hour and a half or Is miles, about
during that time, this unknown variation ceased TO
operate in a great degree.
BY the published log It appears that, after running
from o'clock to o'clock 30 minutes, almost a
northery course, she struck upon point exactly
upon her true course from the mouth OF the Mersey.
Now, how did she get so far south except an UNI
known error IN her eompasses carried her there and
which would, as have said, carried her too far
south Of the Calf OF Man lights, to nee them in a
hazy night. The courses steered were the true
courses, but those would certainly carry him
where they did from his position, and by them he
could not have got into Dundrum bay had he not
FIRST gotten some fifteen miles southerly from the ST.
Johns point lighthouse; and in this case the want
Of that light upon his chart must have proved dlsas
trous for running almost northery as long he did
and then making an unknown stationary light, the
result - not TO be wondered at except that he ina
gined IL the Calf Of Man, which is a revolving light
From the course he ran before and after making IL,
should not have been surprised had he supposed IL
- La al. IL.
airy light, and from that the course he ran n. by w
after making the light the proper course, butin
that while heading ". by E., the Peel light
must have borne N. N. T. instead Of ". N. W., as
the log represents One thing is certain, the courses
run, and the place where the vessel struck show she
must have been at least hours south of where
she ought to have been for which there can be no
reason, except that her compasses had a variation
unknown, and impossible 10 be known by the cap
tain.
| have been thus particular upon this case because
It is very likely to occur TO any vessel, and
that my compass will certainly remedy. A remedy
for this will cover all others which TO
a ships compass under the usual projections.
1t is but few months since English steamer
ran ashore, and was lost the African coast, and
when she struck she was heading by her compass
far away from land The charts showed her course
the correct one. The mystery of their disas-
ter not explained until they To clear away
the pinnacle, when it was found file had been de-
posted near the compass, by accident or design,
which had given the variation that caused her loss.
All Of the foregoing evil results my compass will
prevent, by showing the reflections Of the needle
from the true or geographical meridian, chentrsr
they occur, and from any tohaisper Even If the
needle be DETECTED without attraction-by hand
or if il hang upon the pin--or any other
cause-or if taken off the pin and laid upon
the bottom Of the eompass-box, provided no
wind current Of air reaches it, it will show at a
glance, by marks and figures scale, how much
the needle is away from the meridian, in degrees.
With my compass, the British steamer mentioned
above could not have been run ashore; for had they
not discovered the file, they would have seen
at once how much the needle varied. Its action is
not affected by the roll the ship. The improve
ment in no way interferes with the use Of the same
compass without regarding the improvement, as now
used; or the improvement may be detached in an in
slant, and all seamen cannot fail to understand its
usual operations at glance.
! have also improved the compass card, by sub
shutting circle of thin BRASS wide enough to con-
tain the degrees and point works This circle is
painted white, and the degrees and letters printed
upon it, and it is then fastened with to the
extremities of the needle. II Is lighter than the
cards in use, and the entire compass may be sub
merged in water without the least injury, or affect
ing its operations or correctness.
am aware that these assertions will be read with
incredulity by all acquainted with the use Of the
compass; but am ready to submit it to any test,
likely to occur to the compass.
The numbering of my pages admonshes me that
l am trespassing upon your columns, and forbear
many things should like to say upon the nature
Of the notwithstanding the causes, in my opinion,
why the needle assumes a north and south posi-
ton; the difference in action and effect between
magnetism and electricity; the causes of dip, and
variations, natural and local. and the reasons for
the changes which take place in them the know-
edge and proof of which have been obtained
through my compass, instead Of u? being derived
from them, the world has always supposed the
means of determining variations at all times and
places would be. should like to, as shall at some
future time show all my compass will accomplish
But leave its reserved qualities and uses, which
may in the end prove more valuable than those
claim, to the future, together with the history Of
the Origin, rise, progress, and incentives to its dis
covery and perfection, consuming years Of intense
application and patient experiments, with the most
mysterious and subtle of all agents and means
magnetism and the magnet. Bot will, ere long,
furnish the philosopher key which shall open
wider door, and into larger field of Natures means
and works. than has been lately presented to the pa
tien and dilieent scarcher of her Secrets have fol-