Savannah morning news. [volume] (Savannah) 1868-1887, 1884-03-07
THE TORPEDO BOAT ALARM.
Some Interesting Facts About Admiral
Porter's Great Invention.

Some Interesting Facts About Admiral
Porter's Great Invention
Among the vessels which are authorized
to be constructed for the navy in the bill
presented in the Senate on Monday, says
the New York Herald, is one like the ter.
pedo boat Alarm, designed by Admiral
Porter. Hence a brief description Of the
Alarm, which has recently had several
improvements completed. will be Of
interest. The Alarm was designed
as a cruising torpedo boat. carrying a bow
gun. and intended for service not only
in rivers, bays, and harboTs, but along the
sea coast; in fact, tor use under any Of the
conditions Of literal warfare. and her di-
mansions and form were peculiarly
adapted by the designer for that purpose.
The hull is ofIrOn and the forward portion
below the water surface forms a species
Of tube for the support and man9UYering
of the main torpedo spar, which is capa-
bic Of carrying and sustaining the reac-
ton of q torpedo Of such size that its
discharge in proximity to the hull Of the
largest vessel could not fail TO prove in
simultaneously destructive. The spar is
operated in the hold Of the vessel by
proper mechanism.
Above the water surface the forward
portion OF the hull is recessed. and the
principal gun is placed close to what ap-
pears to be the stem, over which it fires
in the straight-line direction. The bow
of the hull above the water surface is pro-
tected by armOr plates one and a half
inches thick, which is an efficient defense.
as the vessel has the power under all
circumstances Of either advance or re-
treat, Of keeping bow on to a foe, whose
shot would consequently be detected un-
der very acute angle.
The gun has no carriage, in the ordinary
meaning Of the term, the null itself act
ing as the carriage, the gun being nova
BILE in only the fOre-and-aft direction on
slides, and depending for training on the
steering screw, which is also the pro-
pellOr. Owing to this mode Of supporting
and using the gun, the Alarm can be
mounted with one of the largest size.
The vessel is thus not only torpedO-boat
but a gun-boat, solving the important
problem of carrying the maximum gun
on the minimum hull and having direct
fore-and-aft fire, with a capacity of
prompt and accurate aiming in azimuth
not obtainable by any other method.
The length Of the vessel on deck is 141
feet; her extreme length is 173 2-l0 feet
and length on water line 172 feet; extreme
breadth. p feet; height from bottom of
keel plate to top of wooden deck, Il 40
feet; displacement, 100 tons; weight Of
hull, 800 tons; weight OF armOr, 10 tons.
The hull is OF iron and arm0red on the
upper portion Of the bows with iron plates
IL inches thick, extending from the deck
to a little below the water line. There is
no wooden sneathing cOppered, no
spars, no rudder, and no keel. The
lower portion Of the bow at the bot
tom of the hull is carried forward
into a beaker snout fifteen feet before the
forward end Of the water line, This beak
carries the spar or pole to which the tor
pedo is affixed, which spar is run out and
in horizontally from the vessels hold
without the exposure of the men working
it. The hull has double bottom, which.
when filled with water, increases the
draught from 10 feet to II feet inch.
There are two horizontal compound en-
gines of the tandem type, which gave the
vessel a developed speed Of nine knots an
hour on a recent trial trip.