Harrisburg telegraph. [volume] (Harrisburg, Pa.) 1879-1948, 1918-06-27
TORPEDO SIGNALS
ON TRANSPORTS
Detection Device Adopted by
the Navy Is of Proved
Value

| New York.-A torpedo detection
device that is of proved value has
been adopted by the navy. says the
Brooklyn Eagle, and is not only be-
ing installed upon all warships, but
also upon all transports and mer-
chant craft that operate in the sub
marine danger zone. which has now
come to embrace practically all of
the North Atlantic Ocean. Many
types of submarine detectors have
been invented and submitted to the
navy, but very few have given prom
Use of being practicable. The one
that has now reached greatest favor,
while it may also serve to detect
the presence of submarines, is pri-
marily useful in giving warning of
the approach of torpedo.
For the non-fighting ship, whose
business it is to escape submarines
and not to seek them, it is more
important to be able to detect tor
pedo than it is to detect the craft
that launched it. The torpedo,
rather than the submarine, is to be
avoided. 1t has already been dem
onstrated to the satisfaction of naval
experts that the device in question
will give warning of the approach of
torpedo when it is considerably
more than a mile distant. If wider
experience with this instrument
proves this to be a general rule. it
is believed that it may result in
| saving as high as 70 per cent. of the
vessels against which torpedoes are
launched.
1t is well known that German SUBJ
marine commanders, as a result of
much experience, become highly ex-
pert in determining the character
of a vessel merely by the sound of
her screws. With their under water
ears alert, they can tell whether it
is a passenger steamer in the vicinity
or a destroyer. different types of
vessels produce different sounds
under water. American naval men
have discovered also that the tor
pedo, rushing through the water at
35 knots, produces a sound peculiar
to itself, a sound SO distinctive that
it cannot easily be confused with
anything else. The problem was to
pick up that sound while the torpedo
was still at considerable distance.
This has been accomplished.
1t makes very little difference
whether the ship armed with the de-
torpedo is coming. That is not es-
sential to taking the necessary meas
ures to avoid it. This is because of
a simple reason. Torpedoes are al
most invariably fired to strike the
broadside of q ship. Submarines
rarely attempt to make a hit when
the victim is presenting only the bow
or stern, because the target is then
too small to give much hope of sue
cess. When a submarine discharges
torpedo intended to strike the side
of a ship it is never aimed at the
vessel itself, but necessarily at a
point where the victim is expected
| to arrive within one or two or per-
haps three minutes. The submarine
must allow for the forward move
ment of the ship, after estimating
her distance and speed and direction.
The German commanders have be-
| come expert in making these calcu-
lations.
If the victim stops or changes her
course after the torpedo has been
launched, then the target will not be
hit, because the ship will not arrive
at the calculated point. Hits that
are made nowadays are almost invar-
iably recorded without the victim
being aware that torpedo is ap-
preaching, or in cases where dis
| covery is made too late to alter the
| course of the ship.
The new torpedo detector is de-
signed to furnish the necessary warn
ing. When the easily -discernible
sound of torpedo is picked up there
is one simple rule for the ship at
tackled. She must reverse her en-
gines and swing sharply out of her
course. If she continues on her way
her commander knows that he will
probably encounter torpedo at 'Ne
point picked out by the submal' 1 :.
If she avoids that point she is s..le
from that particular torpedo and
probably has an excellent chance
of escaping, because by that time she
is zig-zagging and employing other
means to make the target difficult.
The experience thus far had with
this device indicates that vessel
may have as much as two minutes
warning of the approach of a tor
pedo, which is amply sufficient to
enable a ship to stop and change
her course. Any vessel with two
| minutes warning-or even one min
ute-has fine chance to make