Charlevoix county herald., 1912-04-06

ing of every one on board
again calls attention TO the
hazards faced in craft OF this
sort. Compared with the total num-
Der of under water boats built and in
service today, the loss OF life Incl
dent to the development Of these YES
sells Is perhaps not SO great, but the
circumstances surrounding death in
a submarine are such as to make
deep impression.
Much has been done to make the
submarine safer than 1t was Is years
ago, but the ingenuity Of man may
never succeed in making these boats
as reasonably secure from sudden de-
struction as other vessels. The near
est approach to submarine in
strength OF hull is the battleship, and
the very size Of the battleship makes
it possible to minimize the conse-
quences OF damage by subdivision of
the ships interior, especially the
space LYING between the outer and
the inner skins. In submarine, how
ever, an outer and an inner bottom,
with intervening air space, would i'm
pose conditions which would seriously
cripple the efficiency of the craft. In
effect there are double hulls in boats
of this description, but the steel skins
form the bounding walls Of ballast
tanks into which water is admitted TO
increase the dead weight Of the ves-
sells and to cause them to lose just so
much buoyancy. To be sure when run
ming in surface trim the ballast tanks
are a factor of safety, and if damaged
in that condition the submarine is as
we'll off as any ordinary craft Of sim
liar seaworthiness. Unfortunately all
the accidents that have happened to
submarines have occurred when these
boats were either running submerged
or were being trimmed, that is, taking
water ballast aboard for under water
work or when they were deficient in
reserve buoyancy.
Like Corked Bottle.
Take bottle and put some shot into
it, just enough to make it float up
right, and then cork it. 1t will never
sink unless it is punctured so that en-
tering water can eXpel the buoyant
air. If you made a small hole in the
under side OF the bottle, the flask
would sink deeper, but it would not
go to the bottom. 1t would be more
sluggish in response to surface dis
turbances, in fact seem less disposed
than ever to capsize.
Suppose now on the other hand that
you loosen the cork so that air may
escape then the flask will fill quick
| Ixy Mill hn .Io
fore the bottle disappears. In gen.
eral way this is parallel to the func-
tion Of filling the ballast tanks of
submarine, water taking the part
there of shot in the bottle. and the
puncture being duplicate of the
valves which submarine opens to
allow water TO pass similarly upward
into the ballast tanks. But not enough
water from the sea would enter the
tanks If air were not permitted 10 es.
cape from them, and so vents are open
ed in the tops of the tanks, and the
expelled air generally mingles with
that in the free space inside of the
vessel. OF course this produces
slight atmospheric pressure. but it is
not Objectionable.
SO far the submarine is like the
corked bottle, all of her matches be.
ing sealed. Now In order to bring the
under water boat down deeper in the
water, so as TO make her responsive
TO her diving rudders when she is in
nation. more water is admitted to a
special tank, and the cork of this
tank is drawn, the air escaping. but
the matches still remain tight, AS a
result the little craft has still a buoy
ant margin which holds her at the sur.
face; two or three hundred pounds add
ed weight would make her sink. and II
is the commanding officers particular
care to see that leakage does not de-
stroy this reserve.
How They Dive.
The diving rudders compel the craft
to go under water against an impulse
of only few hundred pounds of buoy
ancy. and this buoyancy is always ex.
erting n lifting force to bring the YES
sci to the surface when the engine
stops. To increase the measure of
this SAFETY factor would mean that the
diving rudders would have TO be set
at a greater angle to drive the boat
downward and to keep her under the
surface, and more OF the power of the
engines would be absorbed in this
work, reducing the speed forward.
One gallon of sea water weighs
about eight and one-half pounds, and
the admission of 25 gallons would sub
sequently destroy the working reserve
Of buoyancy OF most submarines. II
would not take much Of hole to let