The Sun.
London, England, 1859-11-21 00:00:00

LONGITUDIYAL BEARINGS IN THE

CONSTRUCTION OF VESSELS.

The following letter is from a contemporary
fost_xcars ago we were startled by the
accident of the Birkenhead steamship breaking
across (from having got upon a rock amidships),
and submerging her whole crew, and numerous
passengers, but consoled ourselves with the fact

that she had undergone the process of length-
ening, and was therefore a patched vessel. But the
Royal Charter was not patched, and yet she has
more decidedly gone to pieces, and shown that
there is no trusting to iron vessels in such circum-
stances.

It is hinted, indeed, that only the worst .species
of iron had been used in the construction of the
Royal Charter, or is used in the construction of

iron vessels generally. If this is so, I need not say
it is a most serious crime, and cannot be too de-
cidedly repressed ; but I have come to be of the
opinion there may be faults in the construction of

lese vessels which at least should be considered at

the same time, and that fault is that there is a want
of longitudinal bearings—that is, bearings along
the length of the vessels, and which appear parti-
cularly necessary in their case.
In wooden vessels this defect does not appear so
likely to be fatal. Their parts are more massive,
they are more intimately combined, and on a strain
more likely to resist a decided fracture. In iron
vessels, as hitherto constructed, I think the break.
ing across is obviously likely to happen.
I have often thought on seeing the keel of an iron
vessel laid down that it is inordinately slight, con-
sidering the numerous dependencies that must be
connected with it, in the name of ribs, and the stu-
pendous weights that are to be laid upon them
both, if only in the engines that are to impel the
♦essel. But I only thought : I did not consider it
necessary or proper to make any observation or
inquiry; but Ido both now. I consider the keels
and ribs of iron vessels greatly too slight, consi-
dering the strain that is brought upon them, and
that both require to be supported in a way which
has never yet been done. No doubt, the internal
planking does something to equalise the weights,
and were that planking firmly united with the
frame of the vessel it might give the vessel some-
thing of the toughness of wooden vessels as well
as the stiength of iron. But there is no such
union.

Hence iron vessels, whatever may be their length,
have no material longitudinal bearings or fasten-
ings beyond their plates, and they are not double
plated. Wooden vessels, on the other hand, may
fairly be said to be double planked. The inner
planking is not, indeed, so thoroughly fastened to
the ribs of the vessels as the external planking is,
nor, consequently, forming so powerful a longitudi-
nal bearing ; but it is strongly united with the ribs,
and the ribs are so close together that they also may
be said to form a longitudinal bearing, as any diver-
gence caused in one rib would be checked by bear-
ing upon the other close at its side. It is different
in fret veswls. The ribs being placed asunder, '
the whole longitudinal strain is upon the keel and
plates. If the keel bends, the plates must rend, ,for
they are not all of equal length. The upper plates
are longer than those immediately under them, and
these are longer than those immediately under
them again. In this way, after the break of the
gunwale, the whole strain comes upon plato after
plate and they necessarily rend like a sheet of
paper taken at the upper edge, or a piece of cloth of
which the upper edge, or selvage has been broken.
I think this teaches us several things.
1. That the keels of vessels should be of strength
to sustain a great strain against hogging or indent-
ing; that is, against being doubled up if the ends
of the vessel are placed upon two rocks apart, or
broken across if placed amidships upon one rock.
2. That not only should the plates of vessels be
assisted by powerful gunwales, but I think also by
regular longitudinal bars of the strongest iron run-
ning along and connecting with the ribs, making
the circuit of the vessel, and this in strength, like
internal longitudinal ribs or hoops, that, in case of
any disruption of the plates, would one after the
other resist the breaking across of the vessel, or
even any serious indentation of her plates.
Nor is this enough. The structure of vessels is
often likened to that of fowls. Well, every fowl has
a breastbone, and the keel of the vessel may be
likened to the breastbone of the fowl. But the fowl
has also a backbone, and between these and the side
bones is a perfect spheroid.
Again, men and all quadrupeds or beasts have
also backbones and breastbones. The back of men
or quadrupeds may be broken, but the carcass does
not therefore come asunder. Before the most expert
butcher can divide the carcass of a sheep into chops,
or the carcass of a bullock into ribs of beef, he must
first divide the breastbone or remove it ; and in the
same way the human body cannot be divided and
made to fall asunder till the sternum, or breastbone,
is removed. Then the ribs may be divided, or the
back brokon7,--in short, the carcass broken across
with the greatest ease; but not until then.
A vessel with only a keel (or backbone) and ribs,
and only laterally held from collapsing by the cross-
beams supporting the deck, or by the planking of
the deck itself, appears to me to want a great ele-
ment of strength, in wanting longitudinal bearing,
or bearings, equivalent to the breastbone in man and
animals. The crossbeams for the deck, while they
prevent the sides of the vessel from collapsing or
falling in, yet do not strengthen her longitudinally,
nor do the deck plankings. These last may be said
to keep the stem and stern from coming together,
yet do not prevent them from going asunder, nor,
consequently, the vessel from falling to pieces, and
to prevent this last is precisely what is wanted.
In short, vessels of every description ought to
have longitudinal bearings along the ribs to
strengthen the ribs and plates; and on the deck or
decks to have main beams connecting themselves
with the stein and stern, and the supporters of the
bilge plates at such intervals as necessary arrange-
ments will allow, these beams being of strength
sufficient to resist either pressure or strain, and so
to prevent the vessel from doubling up or being
torn asunder.
In this way, from the lateral fastenings going
round, and the floor and deck fastenings traversing
them, the frame of the vessel would be a perfect
spheroid in bearings. It could neither be hogged
nor indented at the keel, nor broken across, nor
dismembered by any strength of wave. It might
be poised on a rock or between rocks, raised up and
dashed down by the waves, but it could not be
disintegrated.
V" Tota in sese teres hebes, atque
rotunda," its sides might be pierced, but they could
not be stove in ; it might be battered in any direc-
tion, but not broken asunder; and this is what is
wanted; and while this woald protect upon rocks,
or on the shore, water-tight compartments (then no
more to be torn asunder) would prevent its sinking
at sea ; an oblong basket, trussed round, and over
and under, will give a distinct idea to any one de-
sirous of understanding me of the bearings I would
introduce in vessels; and they could in no way in-
terfere with the sailing qualities of vessels impelled
by steam.
I need not say that stupendous things have been
done in vessels, but many great things have been
done in many arts, and yet without entire regard to
science ; and the building of vessels in iron is at
least working in a new material, and it is possible
in a material requiring changes in the mode of using
it. At least, we have seen in two very painful in-
stances that, as hitherto used, it disappoints ex-
pectation in the matter of tenacity in circumstances
of great strain. I have shown that iron vessels as
hitherto constructed may be expected to double up,
or break asunder ; and also, as far as I can, how
both may be obviated ; and if experience and un-
prejudiced shipbuilders or men of science shall