The Scranton tribune. [volume] (Scranton, Pa.) 1891-1910, 1899-05-11
COMPASS FALLIBILITY.
The Possible Cause of the Loss of the
Steamer Mohegan,

| pass is above all things a supersens-
| tive instrument renders IL peculiarly
| liable to those sudden and capricious
changes of which many navigators can
speak from experience and to their sor-
| row.
The compass of today is perhaps as
| perfect a production as the highest
scientific skill and the most delicate
mechanical manipulation can attain to-
and yet at critical moment, and by
| causes beyond human foresight, the
vagaries OF it's readings may lead the
most experienced seamen into utter
disaster.
If, as has been said, there should
exist in the vicinity of the Menacles a
a powerful and uncertain magnetic
field by whose influence vessels have
at times been quite inexplicably drawn
! miles out Of their course. then the ter
| rible loss OF the Mohegan might we'll
be explained by this hypothesis alone
And 1t should be borne in mind that
this suggested solution of the mystery
is strengthened by a reference to the
case of the Palmyra lost on the Mana
cles on March IA, 1885. Here the COM
! mander. Capt. Minoff, was steering, as
he believed due west after passing the
| EddyStone, and thought he was some
dozen miles off the Manacles and four
or five from the Lizard when his ship
struck the fatal rocks.
But there are other causes which
may, separately or conformity with the
supposed magnetic field in the vicinity
of the Mohegan's loss, have contributed
to disturb her compasses. For in
stance, we are told that the vessel had
recently undergone extensive alterl-
tions. If in the course of carrying out
these any considerable hammering of
the beams or plating were necessary,
then that part of the metallic structure
may have had its magnetic polarity in
terlered with, even to the point of re-
versal If such We're the case, it would
be interesting to know whether the
compasses We're readjusted to meet the
altered conditions before the vessel
proceeded on her last and, as it proved.
calamitous voyage. Again, there is
the possibility of compass deviation
due to the presence of the dynamo,
whose large external magnetic field
would probably be lying dormant un-
til the lights were switched on, per-
haps only some hour or less before the
Mohegan struck. such a detection
|
is, without oscillation Of the needle
directly as the number OF lights turned
on. In the experiments on the Royal
ist one wire from the dynamo was led
under the standard compass at a dis
tance of thirteen feet, the return being
separated only five feet from it. With
these conditions il was observed that
current of about 100 ampheres caused
detection of eight degrees in the
compass, which, indeed, resolved itself
into an excelle%> dead-beat galvano-
meter the DETECTION increasing and
decreasing, without oscillation, for
.. every variation Of the current.
That such exaggerated conditions
|, existed on the Mohegan we do not for
a moment suggest, but that these dis
turbing influences may have been pro-
duced on a minor scale is we'll within
the bounds of probability We have
seen a sensitive needle Jump" to the
influence of the magnetized ribs of an
, otherwise inoffensive and innocent
: looking umbrella, and many of us have
suffered the Inconvenience of a mag
netized ribs of an otherwise inoffensive
and innocent-lO looking umbrella. and
many of us have suffered the incon-
Nenience of magnetiZed watch--a
small mass of metal, truly, but per-
maps i'll the pocket Of an officer near
the pinnacle all sufficient to deViate
the SenSitively poised compass card.
| Hitherto, with one exception we have
, dealt only with possible and unfore-
seen disturbing causes that may have
; existed within the ship and baffied
\ even so experienced a navigator as
Y capt. GriththS. OF disturbing influ-
; ences beyond the ship. probably the
; most troublesome of all is the Sub
; permanent source OF error due to the
constant action of the earth endeavor-
= ing to form in that part of the ship
5 nearest north a pole repellent to the
l north point of the cOmpass--a source
= OF error the peculiar danger of which
l arises from the fact that as it accumu-
5 lates it produces no visible effect on
I | the compass while the vessel is steer
3 ing steady course, and only becomes
t apparent on altering course. Thus, to
> eXaggerate the Mohegan's course, il
r Capt. Grifiiths had been steering west
D for some days, and then altered his
e course at right angles to south the
{ ! greatest effect would have been pro-
duced, as in every case this error
causes the vessel to err in the direction
: Of the course previously steered An
error Of less than half a point in the
3 long stretch of siXty-tWo miles from
} the start to the Lizard would have
' been sufficient to cause the disaster
? and from any one of the causes we
; have enumerated this slight fallibility
OF the compass, with its terribly disas-
tIous consequences, may have been set
+ up.
c In concluding our consideration of a
probable cause of the loss Ef the MOhe-
| gan we cannot but regret the action OF
: some Of our contemporaries in drawing
. ! comparison between the conduct of
G the officers and men Of the Bourgogne
q ana those Of the Mohegan. KNOWING, as
r We do, what the rln-raff of the steer
e age means, We never attributed the
b atrocities which took place after the
$ Bourgogne collision to the action of
% her crew, and We believe that the
u French officers died, when the time
: came az did those Of the Mohegan. M
= their posts, and with heroism which
\ could not have been surpassed. Had
7 the Boursogne steerage passengers
! been under the sterner orders which
I would have marked the control of a
British, American or German crew we.
\ however, believe that the proportion
of crew 10 passengers saved would
! have been more creditable to the ship.