The Washington times., 1901-08-04

lactly how far such a ship NAV be injured
without becoming unseaworthy, as we'll
as how she may be expected to behave
after certain definite damages incidental
to battle or storms have been inflicted
on her The difficulty has been solved
however. by the discovery of the fact
that the stability of a given battleship or
cruiser under damaged conditions can be
figured out with almost mathematical
precision by the use of models while the
original, for whose benefit the experiment
is being carried on, may be cruising
peacefully in the antipodes,
These tests by models were originated
by a French naval constructor, Bertin.
who first employed them i'm study of one
OF the French cruisers. His method was
taken up and exploited by Naval Con-
structor Woodward of our own navy, and
was soon after adopted in Boston by :,,-of
Cecil II. Peabody, the head of the insti-
tute's department of naval architecture
as a regular part of his courses. Briefly
stated the object in all the tests which
have been made, here or abroad. is to find
out what will be the effect of tearing open
| the compartments Of n warship, singly or
in various combinations whether the
cause be gun fire, the explosion of a tor
pedo, or ramming, or an accident at sea-
such collision or striking on an un-
| charted reef
Modern ships of war, as everyone
Knows, are protected against the fire of
an enemy either by an arrnor belt or by
| * protective deck, so called; or, some
times, by combination of the two. This
leads to the division of fighting Slips into
two classes, namely. the armored rhips
and the protected ships The office of The
| armor belt is to exclude all except the
| heaviest projectiles-in fact, 1t Is practi-
cally impenetrable by shells containing;
| really effective proportion of explosive
| material. and therefore ship protected
by an armor belt is exposed .nly to such
| comparatively insignificant injuries as
| might result from solid shot. The Fro
tective deck, on the other hand. which
! starts from little below the water line,
and is shaped much like a turtles sEell,
| Is intended to defect missiles CT every
| description from the engine rooms and
| boiler rooms-the vitals of The ship-lnd.
by warding off injury from the lower por
| tions of the hull. to keep the buoyancy
| and as far as may be, the stability of
| the vessel unharmed. This latter end.
| however-the protection of the ships sta
| bility-is very imperfectly s:tained. so
that protected ships are in constant rcril
| OF losing their equilibrium from a we'll
aimed shot from the enemys guns, al
| though the danger happens to lie mini
| mized in actual warfare py the fact that
| such ships commonly engage in action
| from so great q distance that a serious
injury near the water line can seldom be
inflicted
\ The question of stability can be solved
| by computation. without recourse to the
use of models, but the computation re-
quired is exceptionally tedious and diff
| cult. In the method invented by Bertin,
| a complete model is made of the ship
| whose stability is to be studied, the line
| of the hull being copied In every detail up
to the point of safety-that is. just be-
| yond the line above which shot and shell
| may be disrcgarded as a factor in en-
dangering the buoyancy of the vessel.
This miniature huh contains a number of
removable wooden blocks representing
| the ships compartments. The blocks
amidshirs represent the compartments
for the engines and boilers, and the for
ward and after blocks the compartments
of the holds or magazines. Then. in or
der to demonstrate the behavior of the
ship when one of the various compart-
| ments is broken open TO the sea, the
wooden block which takes its place in the
model is removed and its weight and the
weight of the incoming water made up by
substituting for the block piece Of lead
OF the proper size, with the center of
gravity in the same place. In general the
effect OF removing the block and adding
the lead is to sink the model deeper in the
water and to cause il to take on a definite
inclination or to change trim-or to do
both. In this condition of simulated
damage the model is still further inclined
by moving weight athwart-ships on a
graduated scale. thus permitting of a d.
rect experimental determination of the
models stability until all stability disap-
pears and it is evident that the ship on
which the model is patterned would be
hopelessy capsized
In the case of experiments on a pro-
tected ship the most interesting question
is the effect of breaking open the COM
partments above the protective deck A
vessel of this class which was re-
Gently studied at the institute had
four upper coal bunkers on each
side above the protective deck and
the experiments which were made
on the model showed that If all the
bnnkers on one side were flooded the ship
would Immediately capsize When full of
coal the bunkers might be broken open by
an enemy's shell without any special
harm being done; but they will be full of
coal only when the ship has her full sup
ply coming out Of port and they probably
VIII not be full when the need is great
est, since the coal must be transferred
from the upper to tho lower bunkers as
soon the latter are emptied or the ship
Will be top heavy This special liability
to danger is found to exist to some ex-
tent in the case of all protected ships, and
the fact has been one reason for the re-
cent development of the new type of ar
mored cruiser
The study of battleships by means of
models has brought out a number of
shown that If single engine room or a
single boiler room is flooded the loss of
stability is very serious, and that IL two
compartments. as, for example, the boiler
room and the engine room on the same
side of the ship, are flooded the ship will 4
obviated. Ii has been found. by connecting
compartments, which adjon transversely
by door. When this door is opened and
both compartments are thus flooded
equally on line running across the ship
she will settle an even keel; she will not
lose stability.
Supposing two engine rooms to be food
ed in this manner, the motive power of
the ship would be temporarily put out of
commission; but If the door between the
two compartments were -afterward closed
the unin1ured engine room-the one which
had not been shattered by the actual fire
of the enemys guns-might be pumped
be trimmed by flooding boiler room on
the same side of the boat The expert
ments with the model show conclusively
that If this were done the ship would not