The Liverpool Standard, and General Advertiser.
Liverpool, Merseyside, England, 1854-10-10 00:00:00

compasses in iron ships, visited, on Tuesday last,

's, having previously seen the
Accompanied by two or

several of our building-yar
Birkenhead-yard of Mr. Laird

three gentlemen, who were witnesses of his experiments,
he verified in a most remarkable and conclusive manner
the deductions he had previously set forth at the meeting
of the British Association at Oxford in 1847, and in his
Magnetical Investigations published in 1852. In the
yards of Messrs. Cato, Miller, and Co., Messrs. Rennie,
Johnson, and Co., Messrs. Verney and Co., where several
iron ships were in progress of construction, and from the
proprietors of which he received every courtesy and atten-
tion, the magnetic action of the several ships on a delicate
pocket compass, wherever they might. be tried, was in
exact agreement with his announcements before any trial
was made. Thus, on approaching the bow of a ship, it
was predicted that the south point of the compass would
be attracted by the lower part of the stem, when, on mak-
ing the experiment, the specified pole pointed directly to
the part near which it was brought, so as, when the com-
pass was carried from the starboard to the port side, to
make half a revolution of the needle. The like attraction
of the north pole, after being first notified, was as stri-
kingly verified on ascending to the upper works of one of
the ships—every portion of iron approached by the, com-
pass there showing strong southern polarity.
A long slip of iron picked up by Dr. Scoresby in one of
the yards was then made use of to test the principles he
had elsewhere propounded respecting the terrestrially
induced and retentive magnetism. Being struck a blow
with a piece of wood (a wedge) in a suitable position, the
iron slip was presented to the compass, whilst resting on a
piece of timber, in a horizontal east and west position,
when it exhibited no more influence than a piece of brass..
The slip being raised up into a vertical position, the poll.-
rity of simple terrestrial induction was shown, which was
reversed on reversing the iron. A blow with the wooden
wedge, whilst the iron was held upright, elicited an intense
energy of retentive magnetism, which was instantly re-
versed by striking the slip against a post the contrary way
up, and finally neutralized by striking it again in a hori-
zontal position.

Again, a piece of old iron, taken out of a ship, was
tested. It was part of an angle iron, or rib, belonging to
the floor of a ship--of the shape, compressed, of the letter
13. It was first placed with the ends on the ground, and
the convex edge upward (like the letter U reversed) in an
east and west line—the reverse of the position it occupied
in the 4hip—and a single blow was struck against it with
a large hammer. The original magnetism was instantly
changed, and the ends resting on the ground, just accord-
ing to theory, were found vigorously to attract the south
pole of the needle and repel the north. The angle-iron
was then reversed, and the points held upward, in the
position it had been fixed in when in use. One blow of
the hammer reversed the polarity, and the upper ends of
the U were found now to have energetic polarity attract-
ing the north pole.

The whole series of experinients, it may be added, were
so striking and irresistibly conclusive, that they were
looked upon, by the gentlemen present, with unmixed
admiration and surprise.
What the reverend gentleman seemed anxious to impress
on the minds of those, interested in iron ships was to this
effect :—that, from the experiments they had witnessed,
and the results now obtained on vessels he had never be-
fore seen, it was evident that these phenomena were the
effects of the immutable laws planted by the Great Creator
in the materials with which they had to deal. It was the ,
obvious part, therefore, of true wisdom to endeavour,
where the direct effects of such laws were available for
useful ends, so to employ them—as in the case of the
earth's magnetism, of which we availed ourselves for
directing the compass needle; and where these operated
embarrassingly or dangerously--as in the case of the de-
viating action of the magnetism in iron ships—to seek
either to discover means to overcome the misguiding infiu-
once, or to bring to light the disturbing circumstances,
and so to guard against any dangerous effects.
It may be added that, on a subsequent day, Dr. Scoresby
made a long series of experiments in Mr. Laird's-Liverpool
yard with a view of testing his deductions on the peculia-
rity of the magnetic distribution with reference to the
direction of the ship's head on the stocks, and it was satis-
factory and important to find all his theoretic deductions
rigidly verified. As, for instance, in ships with their heads
lying towards the east—as to which he had previously
shown that the magnetic intensity should be different on
the two sides, and that the starboard side, by reason of
the axial direction of the earth's magnetism lying over in
that direction, should be most highly magnetic. His pre-
dictions were completely realized in all the cases (three
large ships), which he had had the opportunity of trying.