Popular Mechanics, May, 1915, pages 647-650:

DIRECTING  THE  WAR  BY  WIRELESS

By  GEO.  F.  WORTS

U. S.  Licensed  Wireless  Operator,  First  Class
THE European war cloud burst at the psychological moment in the career of wireless telegraphy, for only very recently has the art based on the science of ether waves been reduced to the reliable basis of a sound industry. Five years ago, or even less, wireless could not have responded to the exacting demands which this war is putting upon it.
    At the beginning of hostilities cables and telegraph lines were ruthlessly cut. Germany, more than any other belligerent, has been in an exceedingly trying position as regards external telegraphic communication, surrounded as she is by enemies on all sides. Her main cables have been cut or disconnected, so that now her only electrical communication with the outer world is by wireless. At the outbreak of the European war, Germany had 17 government wireless stations, Austria-Hungary, 4; France, 18; Russia, 28; and England, 47.
    One of the first tasks of the wireless of the various warring countries was to fill in the gaps caused by severed cables. As later incidents have proved, however, that was only an insignificant portion of the work. Hundreds of miles of roaring battle line, hostile warships roving the remotest wastes of the sea, aeroplanes and Zeppelins soaring high above the earth, even the stealthy submarines, lurking in the depths for victims, are subservient to the invisible hand of the wireless.
    The wireless equipment with which General Joffé keeps in touch with the fighting line of the allies has a range of 200 miles, and is portable. Within 15 minutes after the command is given, the station can be erected and put in operation. At the front, smaller and lighter equipments, known as "knapsack" stations, are employed. These are so constructed that one complete set can be divided up and carried by four men, with an average weight to each man of 20 lb. Five minutes after the command for erection is given, these sets are in operation.
    Besides the knapsack stations, a new and ingenious auxiliary equipment has been devised for cavalry scouting duty, called "whisker wireless." This odd name arises from the bristling appearance of the antennae which project like the quills of a porcupine from the horses' flanks.
    "Landing stations," having a range of 50 miles and designed for impromptu service, are used by the marines. For example, when a cruiser anchors off shore and sends a detachment of men for scouting duty, they carry with them this very compact equipment which can be set up hurriedly.
    Probably the most novel use to which wireless has been put in this war is in aeroplane service. The equipment installed on the French and Belgian fliers weighs about 100 lb., and is exceedingly compact and simple. The metal frame of the aeroplane forms the antennae, while a long trailing wire is used for "ground." This wire is attached so that should it become entangled in a tree or other obstruction, it automatically pulls loose, and another one is substituted.
    Wireless communication over a distance of 54 miles has been carried on from an aeroplane to a land station in the U. S. Army, but greater ranges than five to ten miles are not practical or necessary. In service, the wireless-equipped aeroplane is sent on scouting duty over the enemy's lines from a base at which a knapsack station is located. It is rarely necessary for the aeroplane to fly to a greater distance than two or three miles from this base. As he flies over the enemy, the operator telegraphs the condition or maneuvers of the enemy to the knapsack station. Surprises on both sides are constantly being frustrated in this manner. As a matter of incidental interest, it is due principally to this fact that there have been no recorded surprise attacks made by either side on the Franco-German frontier and that a deadlock exists now.
    The wireless telegraph comprises an important part of the equipment of Zeppelins. Much greater transmitting power, due to a larger space allotment, is made possible on the Zeppelins and French dirigibles. A greater range also results from the use of a larger antennae system.
    A wireless direction finder, to supplement the aeroplane spying service, has recently been adopted by the British for the purpose of locating wireless stations at German artillery bases. When the approximate location of a battery is thus found, the British and French guns are trained upon it. An English radio engineer, who recently visited this country, made the statement that by means of one of the field direction finders the exact location of the admiral's ship of the "hidden" German fleet had been discovered by an officer.
    The secrecy of the interior of submarines is proverbial, but it has been stated on authority that a wireless equipment of short range is in use on the majority of underwater craft. When a submarine is cruising on the surface, a short mast, or the periscope tube, is used for suspending a small antennae system. The equipment closely resembles the aeroplane installations. For an aerial conductor, when the craft is traveling submerged, an insulated jet of water is substituted for the regular antennae.
Wireless Range

    Practically every move that the British, French, or German fleets make is the result of a radio order from the respective war office. The impotence of Germany's bottled fleet at present rather limits this use of her wireless service, although the British fleet relies upon orders via radio exclusively. England directs the maneuvers of her fleets from the Marconi station at Carnarvon, Wales; Germany, from Nauen, and France, from Paris. Except for one hour each day, Carnarvon transmits the orders of the British Admiralty to the various ships in a very complex secret code, which is changed daily. To further insure secrecy, the wave length is frequently and suddenly changed. The principal advantage gained in directing fleets wirelessly is that fewer ships can now do the work of the many which were formerly required. Before the days of radiotelegraphy, ships of a fleet clung together, and orders were either semaphored or carried from ship to ship by fast cruisers. A naval battle line, 200 or 300 miles long, is now quite feasible, while in the days before wireless telegraphy one only a fraction of that length was possible.
    Except when a warship is actually under fire the wireless room is perhaps the liveliest place on board. Every message caught on the instrument, whether intended for that particular ship or not, is delivered to the captain. Whenever anything suspicious is sighted--smoke on the horizon or a speck in the sky that might be a Zeppelin--it is immediately reported to the rest of the fleet. Aside from messages of a general character, such as this, the operator must be constantly on the alert for battle orders from the admiral. The rôle played by the wireless operator in war time is certainly not a desirable one, at least from the standpoint of personal safety. He is always shut up tightly in his room, fully aware of the dangers of attack by air, sea, and submarine.
    The Eiffel Tower station at Paris has a most systematized method of collecting information from all parts of the war zone. By the use of an ingenious recording apparatus, any number of messages, up to ten, can be received simultaneously. An incidental purpose of the Eiffel Tower plant is to transmit news to the soldiers in the trenches. The tremendously high-powered transmitting apparatus, combined with the 900-ft. high tower, makes a 3,000-mile range possible, so that France is kept in constant touch with her fleet.
    Perhaps the most romantic use to which wireless has been put in the war was in the case of the "Emden," the German cruiser which, early in the war, sank many British merchant ships in the Indian Ocean. It is stated by those who claim to know that the "Emden" received all its instructions direct from the enormously high-powered station of Nauen, Germany. The signals sent out from Nauen are so powerful that they can very often be heard on amateurs' instruments in the United States--a distance of nearly 4,000 miles. With this exceptional working range, the "Emden," or any other ship for that matter, might receive orders if she were cruising near Greenland, Rio Janeiro, Cape Town, or Singapore. It is quite probable, therefore, that the "Emden" accomplished her work from orders or information she received from Nauen while she was cruising in the Indian Ocean. Strangely, wireless also proved the "Emden's" undoing. Just before she attacked Direction Island and demolished the wireless and cable stations there, one of the Direction Island wireless operators flashed out an S O S call. This was picked up by the "Sidney," and the engagement shortly followed in which the "Emden" was sunk.
    The "Karlsruhe," another German ship, acting with her convoys, adopted an ingenious dragnet method of capturing British vessels. The German cruisers reduced the sending radius of their apparatus to 30 miles, and traveled forward in a circular formation no more than 30 miles in diameter. When an enemy was sighted by one of the circle, the others were notified and the ring closed in on the helpless victim. By thus reducing the transmitting range the possibility of attack by British warships was very slight.
    The inevitable command of the Germans upon capturing a ship is "Don't use your wireless!" Usually that order is followed by imperative instructions to cut down the antennae and throw it overboard together with the instruments. For what is so helpless in these days as a ship without wireless?
    The British war code is so complicated that it should be insoluble. Once, however, the Germans used it to advantage in a "fake" message. When the war started, the "Breslau" and the "Goeben" were bottled in the Strait of Messina, between Sicily and Italy, by a British squadron. During the morning of August 6, the British commander received a wireless message, apparently from the British Admiralty, ordering the release of the "Breslau" and the "Goeben." Not until long after the two German ships were safely at sea was the falsity of the message discovered.
    One of the most interesting phases of the wireless-in-war-time question concerns secretly operated stations. The press, on numerous occasions, has appeared with the announcement of the existence of a hidden wireless station in this country operated by one of the belligerents. This possibility is so remote as to be ridiculous. An amusing example of this occurred recently when various newspapers announced that the "Germans and Japanese were suspected of operating hidden plants in Lower California and the Maine woods." Whoever was the well-meaning source of this information, the fact remains that the supposed "German station in Lower California" was none other than the new Marconi trans-pacific station at Bolinas, Cal., while the "hidden radio plant" in the Maine woods turned out to be a perfectly harmless commercial station at Wellfleet, Mass. The U. S. Government would have a tremendous task on its hands if an attempt should be made to dismantle all privately owned stations, as more than 100,000 of them exist. Germany, France, and England, however, whose wireless laws have always been much stricter than ours, have ordered every private aerial down and all instruments disconnected.
    Numerous "wireless spies" have been discovered in all of the warring countries, and when convicted they have met the customary fate.
    Interference with wireless messages as they are now handled by the perfected army and navy equipments is practically impossible. Telegraph wires and cables may be cut, but a wireless wave cannot be stopped. "Jamming," or sending out waves of the same length as a transmitting station to confuse the receiving operator, is averted by making frequent changes of wave length at known intervals.