WIRELESS IN THE ARMY AND NAVY. WIRELESS ON AN AEROPLANE. HOW A
MESSAGE IS SENT AND RECEIVED.
Wireless telegraphy and that precocious infant, wireless telephony, have
outlived all the speculative and tentative achievements of their early
days and have established themselves in an important and settled
position among our methods of conveying intelligence.
The field has been so greatly enlarged in recent years and the apparatus
and methods so improved that the broadest possible view of its future
development and importance is justified. And there must inevitably come
the time when our merchant marine and wireless service will come under
such reasonable regulation that it will be removed from any dependence
upon stock jobbing wireless telegraph and telephone companies.
[Illustration: FIG. 100.—Special light weight wireless telegraph set
for airship service.]
Official sources show that the equipping of sea-going vessels with
wireless apparatus is progressing at a rapid rate and it is not
difficult in the face of certain facts to appreciate the enormous volume
of business that sooner or later will be handled by wireless. Three
hundred and sixty-three United States naval vessels and about eight
hundred merchant vessels are equipped at this writing. The large number
of commercial shore stations, army forts and posts, and those used by
corporations, isolated stations, etc., for various private purposes
comprise a list which reaches an enormous total.
[Illustration: FIG. 101.—Telefunken wireless cart, showing
transmitter.]
Whatever may have been the status of wireless previous to the Titanic
disaster, it now occupies a position far more important than that taken
merely from any commercial standpoint, for it is no longer merely a
convenience to business or a means of furnishing the latest news for the
entertainment of passengers, but is a life-saving proposition taking its
place with the elaborate and costly systems of railroad signals.
[Illustration: FIG. 102.—Telefunken wireless cart for military service,
showing receiving apparatus.]
[Illustration: FIG. 103.—Telefunken wireless wagon set in operation
at Fort Leavenworth, Kansas. The aerial is of the umbrella type
supported by a steel pole resting on a porcelain base.]
It is a curious fact that many of the most startling and newest
inventions find ready and peculiar application as an aid in modern
warfare. The nerves of every war vessel and fort are the wires of the
telephones, telegraphs, telautographs, dynamos, storage batteries etc.,
that transmit orders by speech or in writing, find the range, fire the
guns, explode the mines and seek out the enemy with a powerful
searchlight.
Every battle-ship, cruiser, etc., of the United States Navy is now
equipped and with the completion of the new ultrapowerful station at
Washington the War Department will be enabled to issue instructions to a
ship no matter where it may be on the ocean or in what harbor it may
lie.
The government maintains an elaborate equipment at the Brooklyn Navy
Yard where the future wireless operators of the Navy are given a course
extending from seven to ten weeks. The first few days are spent in
mastering the theory. The second week usually commences alternate study
and practice of the Continental Code which lasts throughout the entire
course or until thoroughly mastered. Each week some special branch of
study is given out such as repairing and overhauling certain
instruments. At the end of seven weeks the student can usually send and
receive 15 words a minute. He is then given two weeks to prepare for an
examination which if passed rates him as an electrician, third class,
and qualifies him for active work.
[Illustration: FIG. 104.—Wireless room aboard the U. S. transport
"Buford." It is certain that wireless telegraphy and telephony will
be important factors in military campaigns of the future. For coast
defense, wireless is as valuable as on the ocean.]
[Illustration: FIG. 105.—The apparatus set up for operation.]
This method of transmitting army orders is quite dependable. With the
most recent developments and improvements it is now possible to direct
the movements of a great army and navy simultaneously from a centrally
located point.
[Illustration: FIG. 106.—Wireless equipped automobile.]
One of the most interesting and spectacular applications of wireless
telegraphy in military service is the wireless telegraph automobile.
The automobile is a stock pattern touring car of 30 H. P. provided with
a special body arranged to carry six passengers. The seats are elevated
so as to afford storage space below for the entire wireless equipment
and a truly astonishing amount of miscellaneous supplies.
[Illustration: FIG. 107.—Company D Signal Corps at San Antonio Texas,
1911, showing pack sets and telescoping pole carried by pack mules.]
The mast used to elevate the aerial is of light steel construction
divided into eight sections which nest into one another with admirable
economy of space. The socket for the foot of the mast is located in the
center of the tonneau. Only a few minutes are required to raise the mast
and aerial. The same gasoline motor employed to drive the automobile
also drives a small dynamo which supplies the electric current for the
transmitting apparatus.
Two of these cars have been experimentally operated over a number of the
old battle-fields of the Civil War.
[Illustration: FIG. 108.—U. S. Signal Corps pack sets shown open and
closed. Receiving apparatus on the left.]
The tests were made under all sorts of road and weather conditions but
no great difficulty was experienced in establishing communication over
distances varying from 35 to 50 miles.
There is probably no application of wireless telegraphy, however, quite
as picturesque as the combination of wireless and an aeroplane and the
idea of a double seated aeroplane carrying an aviator and a wireless
operator hovering over a hostile country to keep the commanding officer
informed of all conditions and movements of the enemy.
[Illustration: FIG. 109.—The receiving apparatus of the airship
"America" (Wellman expedition).]
The huge dirigible balloon Akron in which Melville Vanniman proposed to
cross the Atlantic Ocean was fitted with wireless equipment in order to
transmit news of the expedition en route to various of the daily
newspapers of New York and London and also in case of an accident or
emergency to summon aid.
[Illustration: FIG. 110.—Interior of the N. Y. "Herald" (O. H. X.)
press station.]
The equipment is interesting because of the peculiar conditions imposed
upon instruments to be used under such circumstances. A three kilowatt
transformer, the latest type of musical rotary gap and a valve detector
were included in the outfit. It was proposed to obtain the necessary
ground connection by trailing a 1200 foot phosphor bronze ground lead in
the ocean. The frame of the balloon was to be used as the aerial. Should
it have become necessary to take the lifeboat which the balloon carried,
a kite would have been raised and by substituting a copper wire in lieu
of a string an aerial provided, and once more a CQ D and its appeal for
aid would have gone vibrating forth through the ether.
[Illustration: FIG. 111.—Operating the U. S. Signal Corps airship
wireless apparatus.]
Several enterprising newspapers have recognized the value of wireless
telegraphy in collecting shipping news and have installed outfits for
the assistance of their reporting bureau. This innovation in modern
journalism has quickly developed into a useful feature of those
publications which have seen fit to adopt it. When the baseball season
is under way every steamship within calling distance wants the latest
baseball scores or sporting results.
[Illustration: FIG. 112.—The N. Y. "Herald" station, showing aerial.]
[Illustration: FIG. 113.—Operator Jack Irwin overhauling the wireless
apparatus for the dirigible balloon "America."]
Railroads have found an auxiliary wireless service to be of the utmost
value in relieving the heavily loaded wire lines between important
centers. During some of the winter storms and blizzards, when miles of
wires were down in all directions, wireless has been the sole means of
communication in certain instances.
The process of sending a wireless message is very simple. The aerial
switch is usually kept in such a position that the receiving instruments
are connected to the ground and aerial so that the operator is always
able to hear any one calling him. We will suppose for illustration that
the land station at 42 Broadway, New York City, wishes to transmit a
message to the steamer "Horatio Hall."
[Illustration: FIG. 114.—Morse code.]
Every wireless station on land or sea has assigned to it two or more
"call letters," which distinguish it from all other stations, and serve
as the key to messages intended for it to receive and when signed to a
message as an indication of its origin. The "call" of the land station
in this case is N. Y., and that of the steamer, J. H.
[Illustration: FIG. 115.—Continental code.]
In order to send the message to the ship, N. Y. throws the aerial into
position for sending. This act also starts the motor generator set
supplying current to the transformer. Pressing the key, the operator
then signals in the telegraph code J. H., J. H., J. H.—M. S. G.–N.
Y.—and gives the "finish" signal. M. S. G. is the abbreviation for
message. The N. Y. operator then throws his switch back into the
receiving position and waits for a reply. If one is not forthcoming
shortly the calling process is repeated.
[Illustration: FIG. 116.—Transmitting equipment of the high power
station at Nauen, twenty-five miles northwest of Berlin, Germany,
showing six induction coils (in the foreground) arranged to charge
the Leyden jars (composed of 360 units).]
[Illustration: FIG. 117.—Duplex receiving apparatus. The set to
the left may be adjusted to receive short wave lengths and that to
the right to receive long waves. When the handle of the "listening"
key, shown in the center of the illustration, is in the center,
the left hand phone of the head set is connected to the instruments
on the left and the right hand phone to those on the right, so
that the operator is always ready to receive either short or long
waves if received. Swinging the key connects both phones to
either set at will.]
As soon as the operator on board the steamer hears the call, he waits
until the finish signal is received, and then responds in the following
manner: N. Y., N. Y., N. Y.—J. H.—O. K., O. K.—G. A.—G. A.—N. Y., J.
H.—and gives the "finish signal." O. K. is the abbreviation for "all
right," and G. A. means "go ahead." Upon receipt of this, the land
station transmits the body of the message, and signs its call and finish
signal. If the steamer understands the message, she replies "O. K.," and
signs.
[Illustration: FIG. 118.—Breaking-in system.]
There are two Codes in general use for wireless telegraph purposes, the
Morse and Continental. It takes about five per cent. longer space of
time to send a message in Continental than it does in Morse, but the
former has the advantage of not containing any letters requiring proper
spacing in order to be recognizable. American coastwise steamers use the
Morse code; transatlantic ships use the Continental code.
One of the greatest disadvantages of most systems of wireless telegraphy
lies in the fact that no arrangement is provided for simultaneously
transmitting and receiving wireless signals. It is usually necessary for
one operator listening to another to have to wait until the finish
signal is given before he can reply or interrupt in case he cannot
understand part of the message, because the receiving apparatus of the
transmitting station is necessarily disconnected from the aerial and the
ground during the period a message is being sent. If it were to be
connected at this time the powerful currents of the transmitter would
rush through the receiving apparatus into the ground without setting up
any very powerful waves in the aerial and seriously injure the delicate
receiving instruments.
The Breaking-in-System is a method of simultaneously transmitting and
receiving wireless signals. This is accomplished by providing the
transmitting key with a second set of contacts, so arranged that when
the key is released between the dots and dashes of the code the aerial
and ground are automatically connected to the receiving apparatus. When
the key is pressed the receptor is automatically cut off. The advantages
of such a system are more or less obvious. When interference or a
misunderstanding occurs the fact can be immediately signaled to the
sending operator, and the message commenced over again.
[Illustration: FIG. 119.—The receiving apparatus of the station at Nauen.
The message is being printed on tape by a recording device.]