THE MARVELOUS TONGUE AND EARS OF THE SUBMARINE
SINCE a submarine has an eye to see with, it is both proper and fitting
that it should have a tongue so that it may speak and ears so that it
may hear. In fact, an undersea boat is almost human.
The early submarine, though, was not only as blind as a cave fish, but
it was as deaf and as dumb as a snail; and since this was the case, it
had to do whatever talking was necessary by means of a deaf and dumb
alphabet, that is, by signaling with flags, or _wigwagging_, as it is
called.
=The Tongue and Ears of a Submarine.=—The tongue of a submarine—or
rather tongues, for it has several—is the fanciful name I have given
to the means, methods, and schemes by which messages are sent from
one submarine to another submarine or to shore, and the ears are the
devices by which it receives messages from other submarines and from
shore stations.
There are two conditions under which messages must be sent from and
received by a submarine, and these are (1) when she is running light or
awash, and (2) when she is running submerged.
Now, most of the signaling systems can be used only when the submarine
is on the surface, and a couple of them can be used only when she is
under water.
Then, again, some systems are good only for daylight signaling, and
others for night signaling; others will cover very short distances, but
there are systems that will send and receive over long distances. But
whatever the system may be there will be found some weak point in it as
far as the submarine is concerned.
=Kinds of Signaling Systems.=—Since no one signaling system will meet
the rigid requirements of the submarine, several systems are used. When
the craft is on the surface, these are: (1) the _flag_, or _wigwag_,
system; (2) the _flashlight_ system; and (3) the _wireless telegraph_
system. When the submarine is under water the signaling systems used
are: (1) the _bell_, or _violin_, system; and (2) the _electric
current_ system—all of these will be described in order and as we go
along.
=The Wigwag Way of Signaling.=—The oldest way of sending messages
at sea is by _wigwagging_, that is, using flags, and this system is
still in use in the navies of all nations for close range daylight
communication.
The way wigwagging is done is like this: Each craft has a signal book
which gives the positions of the flags and the meaning of them. These
flags are usually manipulated by a signalman (see Fig. 55) though
sometimes a mechanical apparatus called a _semaphore_, which has two
movable arms to hold the flags, is used.
[Illustration: FIG. 55. SIGNALING BY MEANS OF FLAGS.]
Two flags are used, one in each hand or on each arm, and each position
of the flags means a letter of the alphabet, and so by showing the
flags in various positions to represent different letters words are
spelled out.
Another scheme that is used to signal with flags is by running, that
is displaying, a number of different colored flags on a _halyard_. The
combinations of flags—or to use the right word, _permutation_, which
means the number of different arrangements of a few flags that are
possible—are numerous and each permutation represents some word or a
sea-term.
Now, you might think that it would take a couple of hundred flags of
different colors to represent a message, and, further, that since there
are only eight colors which can be told from each other at a distance
of half a mile, signaling by colors could not be done.
But this is what you think, and not what you have figured out, for if
you have eight flags of different colors and display them, four at a
time, on the signal halyard you can make the surprising number of 1680
permutations; and this, you will allow, is enough to say anything that
you may have to say.
Although a _code book_ is found in every signalman’s outfit, he is a
chap who knows all the signals by heart and can send and receive flag
messages almost as fast as you can write down the words.
=The Flashlight System.=—There are two methods used for sending
signals at night over short distances, and both are done by means of
light; named, these are (1) the _colored light_ system, and (2) the
_searchlight_ system.
_The Colored Light System._—In this system incandescent electric lights
of high candle power are placed back of _bull’s-eyes_, or lenses, made
of colored glass, and these lights can be switched on and off and so
form combinations that spell out words just as the colored flags do.
This system is very much used for short range signaling at night.
_The Searchlight System._—A searchlight, that is an electric arc light
set in front of a silvered reflector, can be seen for long distances,
and so it, too, is largely used for night signaling.
The searchlight, which can be turned in any direction, has a movable
_shutter_, or metal disk in front of it, fixed to a handle, and when
this is worked up and down like a telegraph key, the shutter cuts the
light off and lets it shine forth accordingly.
By working the key, and hence the shutter, the light is broken up into
dots and dashes of the regular Morse telegraph alphabet, and these
short and long flashes are read by the operator on the other boat.
=The Wireless Telegraph System.=—The wireless telegraph has all the
other systems of signaling, when the submarine is afloat, beaten by
miles.
Among its advantages are (1) it can be used in the daytime as well as
at night; (2) the electric waves it sends out cannot be seen and this
makes it harder for an enemy ship to locate the boat it is on, and (3)
its signaling range is not cut off by the curvature of the earth.
_The Parts of a Wireless System._—There are three chief parts to every
wireless telegraph system, and these are (1) the sending apparatus,
or _transmitter_, as it is called; (2) the receiving apparatus, or
_receptor_, as some “high-brow” has named it; and (3) the _aerial
wire_, which is used for both sending and receiving.
[Illustration: FIG. 56. A, THE TRANSMITTER READY TO SEND. B, THE
RECEIVER READY TO LISTEN IN.]
The sending apparatus is made up of (a) a _source of current_, which on
a submarine is the storage battery; (b) an _induction coil_; (c) a
_telegraph key_; (d) a _tuning coil_; and (e) a _condenser_.
The receiving apparatus is formed of (a) a _tuning coil_; (b) a
_condenser_; (c) a _detector_; and (d) a pair of _head telephone
receivers_. A wireless telegraph set is shown in Fig. 56, _A_ and _B_.
Both the sending and the receiving apparatus can be connected with
the aerial wire by means of what is called a _throw-over_ switch, the
purpose of which is to connect the _aerial_ to the transmitter when
messages are to be sent out and to connect the aerial to the receiver
when messages are to be received. Thus only one aerial is needed.
_How Wireless Works_[28]—When a wireless message is sent the operator
makes and breaks up the current from the storage battery into dots and
dashes by means of the telegraph key.
_This interrupted low pressure current_ flows through the induction
coil and this changes it into a _high pressure current_ which makes a
_jump spark_. The spark in turn changes the high pressure current into
_high frequency currents_, or _electric oscillations_, as they are
called; and as these run forth and back over the aerial wire they set
up waves in the _ether_ which are called _electric waves_.
These electric waves are exactly like light waves, but they are so long
that the eye cannot see them. The tuning coil and the condenser are
used to give the waves whatever length the government says they must
have.
When the electric waves that are sent out by the aerial of the
transmitting station strike the aerial which is connected with the
receiving apparatus of another ship and the operator is _listening in_,
the waves are changed back again into high frequency currents, and
these run to and fro on the aerial wire and up and down through the
tuning coil, the condenser and the detector.
The latter instrument changes the high frequency currents, which are
alternating, into an interrupted direct current; and these in turn
_energize_ the telephone receiver, with the result that the dots
and dashes sent out by the sending operator are reproduced by the
telephone receiver, when they are heard by the receiving operator who
is _listening in_.
The tuning coil and condenser enable the operator to _tune_ his
receiving apparatus to the length of wave which the transmitting
station is sending out, and this operation is called _tuning in_.
The wireless station of a submarine is usually located in the
navigation compartment. Although the aerial is neither high nor long,
messages can be sent to upwards of two hundred miles and received over
much greater distances.
Wireless allows the submarine not only to keep in touch with its _base_
but also to pick up and intercept messages from enemy ships, and though
the operator may not be able to decipher them it is possible for him
to determine in about what direction and at about what distance the
ship is.
[Illustration: _Courtesy of Hilbourne and Clark Mfg. Co._
A MARINE WIRELESS INSTALLATION]
Another use to which wireless is put is signaling between submarines
that are doing patrol duty at the same time but which are too far away
from each other to use either flags or lights.
Wireless telegraphy cannot, however, be used when the submarine is
under water, for water absorbs the electric waves in exactly the same
way that it absorbs light waves. But taken all in all, wireless is by
far the most important of all the signaling systems yet invented, and
it is the only one by which messages can be sent and received by either
day or night, over long distances and in any kind of weather.
=Underwater Signaling Systems.=—As I have said before, there are two
kinds of signaling systems used by a submarine when it is under water.
While both systems leave much to be desired—for neither can
begin to come up to wireless, either in ease of operation or in
signaling range—as they are the only known means by which underwater
communication is possible, there is nothing to do but to use them.
_The Bell or Violin System._—This is a signaling system that is widely
used on ocean going vessels of all kinds to send out warning signals in
thick weather.
It is a system in which a large bell or other vibrating apparatus sets
up sound waves which travel in every direction through the water; when
these waves reach another craft they are heard by means of a telephone
receiving apparatus.
Now, water will carry sound about ten times as far and four times as
fast as air; that is to say, if a bell is struck a blow in air and the
sound waves it sends forth can be heard a distance of half a mile, then
the same bell if it is struck when it is submerged in water will send
out waves to a distance of five miles.
[Illustration: FIG. 57. THE SUBMARINE BELL.]
The sending apparatus consists of either a bell (see Fig. 57), the
striking mechanism of which is worked by electricity, or of a large
saw-toothed wheel which revolves rapidly against a tight wire and
in consequence sets up a musical note. This latter kind is called a
_violin transmitter_.
Whichever is used is lowered through a hatch in the hull of the
submarine, and the bell is rung or the wheel is rotated by an
electro-mechanism, which sends out sound waves to distances of from 5
to 15 miles.
The receiving apparatus (shown in Fig. 57) is formed of an ordinary
_telephone transmitter_, and this is fixed in a small iron tank filled
with water and bolted to the inside of the skin of the hull. There is
one of these transmitters on each side of the ship, and each one is
connected with a battery and a pair of head telephone receivers placed
in the navigating compartment.
[Illustration: FIG. 58. HOW THE SENDING AND RECEIVING BELL SYSTEM
WORKS.]
When the bell or violin of another submarine, or the base ship, sends
out its message in the Morse alphabet the sound waves, as you will see
by looking at Fig. 58, travel through the water and strike the hull
of the ship, go through its skin, set the water to vibrating in the
tank, and this, acting on the telephone transmitter, makes it vary the
electric current of the battery; the varying current flowing through
the telephone receivers reproduces the distant sound of the bell or the
violin wheel, and the operator on the submarine hears it.
The receiving apparatus also serves to detect the presence of an enemy
ship when it comes within torpedoing range by the sound waves set up by
and by which are sent out through the water by the rapid turning of the
ship’s _propellers_.
=The Electric Current, or Conductivity, System.=—In this submarine
telegraph system the water, which is a fairly good conductor of
electricity, is made to carry an ordinary battery current between the
sending and the receiving stations.
[Illustration: FIG. 59. THE UNDERWATER “WIRELESS.”]
Since the water conducts the current of electricity, it is easy to
see why it is called a _conductivity_ system. It is also called an
_underwater wireless_ system, but while it is _wireless_ in the sense
that there are no connecting wires between the two stations, you must
not confuse it with the _real_ wireless system, which uses electric
waves, for in the former the energy decreases as the _cube_ of the
distance and in the latter only as the _square_ of the distance.
_The Parts of the Conductivity System._—There are three principal
parts to this system, and these are (1) the _sending_ apparatus; (2)
the _receiving_ apparatus, and (3) the _submerged copper plates_ which
conduct the current from the sender into the water and from the water
into the receptor.
The sending apparatus consists of (a) a _source of direct current_, and
the storage battery supplies this; (b) a _reactance_, or _kick coil_,
as it is commonly called; (c) a _rotating interruptor_, and (d) an
ordinary _telegraph key_.
The receiving apparatus is made up of (a) a _telephone induction coil_,
and (b) a pair of _head telephone receivers_. All of this is shown in
Fig. 59.
One of the submerged copper plates is fixed to the bow of the
submarine’s hull, and the other is secured to the stern, in order to
get the plates as far apart as possible. These plates are connected to
a _throw-over switch_, so that either the sender or the receptor can be
connected to the plates as the operator wishes.
_How the System Works._—The instruments of the sending apparatus are
connected up as shown in Fig. 59. Now when a message is to be sent from
one submarine to another, the operator sets the rotary interruptor,
which is run by an electric motor, to spinning, and this makes and
breaks the current several hundred times a minute as long as he holds
the key down which closes the circuit.
The result is that each dot and dash he makes is formed of a large
number of separate currents, and as these flow through the reactance
coil, it gives each one a little kick and sends it out into the water
through the copper plates; the currents then spread out between and
from the plates in closed lines which extend to very considerable
distances, as shown in Fig. 59.
When these electric currents reach the plates of the receiving
apparatus on the submarine where the operator is _listening in_, they
flow up the wires and through the primary winding of the _telephone
induction_ coil; these broken up _direct currents_ flowing through
the _primary_ coil set up _alternating currents_ in the _secondary_
coil and also raise the _low pressure currents_ into _high pressure_
currents—that is, currents of a higher _voltage_, as it is called.
These alternating high pressure currents then flow through the
telephone receiver, and by varying the strength of the magnet of the
latter the dots and dashes of the sending station are reproduced and
the receiving operator hears them as a musical buzz.