The Story in the Wireless
What Is the Principle of the Wireless Telegraphy?
Drop a stone in a pool of water. Circular waves or ripples will travel outward in all directions. That is the principle of wireless telegraph.
If a chip be floating on the water it will be rocked by each ripple, just as a wireless receiving station will respond to the electrical waves or impulses that make up a wireless message. It is not known just how the invisible wireless waves are propelled through space, but they travel through the ether in the air in very much the same way as do sound waves. The electrical signals, too, are received only by apparatus that is attuned to them; that is, they can not be heard except at wireless stations, any more than sound can be heard by the ears of a deaf person.
The wireless waves have a definite length, can be measured in feet or meters, and are regulated according to the distance the message is to travel. Stations that send a few hundred miles use a wave length of six hundred meters, or less, while at the powerful land stations used for trans-atlantic work the wave lengths used run into as many thousands.
Why Don’t the Messages Go to the Wrong Stations?
So that the hundreds of messages hurtling through space at the same time will not interfere, the wireless stations are equipped with tuning-apparatus through which they can adjust their wave length to receive the particular message desired. A different wave length is used by each ship or wireless shore station, and even though dozens of messages fill the air, the minute the wireless operator adjusts his tuner to the length of the station he is after, that particular message stands out very strongly and all the others grow dim.
How Does the Wireless Reach Ships at Sea?
All ships at sea report their positions regularly; thus it is a simple matter for a shore station to send a wireless message to the ship to which it is addressed. For example, the Marconi station at Sea Gate, New York, wants to reach the Lusitania. The operator looks up that vessel on the list and notes her call signal and wave length. He adjusts his tuner to correspond and calls her signal, M F A, repeating it three times.
The wireless man on the vessel, knowing that he is within range of a shore station, has set his tuner at the wave length assigned to him and is listening. When his call letters are heard, he acknowledges them and signals to go ahead with the message. When it has been given, the Sea Gate station “signs off” with its call letters W S E and the ship operator enters in his record that that particular message reached him via the Marconi station at Sea Gate. Thus, with the wide variety in wave lengths, no confusion of messages exists and any desired ship or shore station can be called, just as a direct telephone connection is secured by giving the central station the call number of the subscriber wanted.
What Kind of Signs Are Used in the Wireless?
The actual wireless message is composed of dots and dashes, which, in certain combinations, stand for certain letters of the alphabet. This is done through opening and closing the electrical circuit by pressing a key, a sharp touch forming a dot and a longer pressure a dash, as with the wire telegraph.
If secrecy in a wireless message is wanted, the words are sent in cipher which, of course, cannot be understood by outsiders. The Government sends thousands of words each day without a single word meaning anything to the wireless stations that happen to be “listening in.” While it is true that any one owning a wireless receiving set may listen to messages flying through the air, every person within hearing who understands the Morse Code can read the telegrams that come into a telegraph office. Knowledge thus gained, however, is of little value, as the law provided heavy penalties for disclosing the contents of any kind of telegraph message.
What Does a Wireless Equipment Consist of?
The various apparatus that comprises a wireless equipment can not be properly explained without the use of technical language, but the general principle of operation is somewhat as follows: If a small loop of copper wire, with a slight separation between the ends, is placed across a room from an electric spark, it will be slightly affected. Increase the electrical current to far greater power and control it, and the invisible electrical wave may be thrown many miles. To send a message across the ocean, the current used by the modern wireless station is so powerful that it will pass through storm and fog, even through mountains, without losing much of its force. When this tremendous force is released by pressing the telegraph key, it leaps from the aerial wires, or antennae, travels across the Atlantic and is picked up by a corresponding aerial, attuned to receive the signal.
The aerial, or antennae, as it is called in a wireless work, is made up of copper wires. On a ship these are strung between the masts, usually consisting of two, four or six wires held apart by crosspieces. Two or more wires lead down from this to the wireless cabin.
The coil or transformer is the apparatus which produces the spark that forms the electrical waves. In small stations, the length and thickness of the spark and the speed of vibration is regulated by a thumb screw. Transformers are used when the power is taken from the alternating current of an electric light circuit.
The gap, which the electrical current jumps when the telegraph key is pressed down, is composed of two rods which slide together or apart to vary the length of the spark.
The simplest type of sending station consists of the antenna, battery, coil, wireless key and spark gap. If a change in wave length is desired a transmitting tuning coil must be added.
The receiving apparatus contains a detector, which is chiefly two mineral points lightly touching and connected with a sensitive head telephone. The incoming signals are heard as long and short buzzing sounds corresponding to the dots and dashes. The receiving tuning coil, used to adjust wave lengths, is operated by simply moving sliding contacts along a bar until the signals are more plainly heard. While the large stations have more complicated apparatus, the principle remains the same.
How High Do Wireless Masts Have to Be?
The towering masts of the Marconi Trans-Oceanic stations are often supposed to rise to their great height, so that an antennae will be raised above the obstructions between. If this were necessary, two wireless stations separated by the Atlantic would have to have masts one hundred and twenty-five miles high to rise above the curvature of the earth. The path of the wireless waves, however, is not in a straight line, but follows the curvature of the earth. Scientists explain this by saying the rarefied air above the earth’s surface acts as a shell enclosing the globe.
The speed of wireless messages is placed at 186,000 miles per second. A wireless message will thus cross the Atlantic in about one-nineteenth of a second—a period of time too small for the human mind to grasp. In other words, the wireless flash crosses in a fraction of a second a distance that the earth requires five hours to turn on its axis and the fastest ships take nearly a week to cross.
The longest distance over which a wireless message can be sent is not definitely known; the present record was made in September, 1910, by Marconi from Clifden, Ireland, to Buenos Aires, Argentina, a distance of 6700 miles.
THE WIRELESS PREVENTS ACCIDENTS AND SAVES MANY LIVES
This photograph makes us appreciate what a wonderful aid is wireless to navigators. On Easter Sunday, 1914, the U. S. Revenue Cutter “Seneca,” patrolling the North Atlantic, found these two gigantic icebergs in the regular steamer lanes and sent out wireless warnings to all nearby steamships.
HOW THE WIRELESS IS INSTALLED ON FAST TRAINS
RAILROAD WIRELESS.—ANTENNA ON CARS.
WIRELESS STATION ON TRAINS.
WIRELESS STATION IN U. S. ARMY
City side of Scranton station, Lackawanna R.R., showing aerial of wireless which communicates with trains.
Photo by Stefano
WIRELESS RECEIVING STATION IN U. S. ARMY.
The Man Who Invented Wireless Telegraphy
Communication without wires for thousands of miles across oceans, from continent to continent, is a far cry from sending a wireless impulse the length of a kitchen table. That is the development of twenty years.
To properly trace the development of wireless telegraphy, however, it is necessary to go back eighty-three years to when, in 1831, Michael Faraday discovered electro-magnetic induction between two entirely separate circuits. Steinheil, of Munich, too, in 1838, suggested that the metallic portion of a grounded electrical circuit might be dispensed with and a system of wireless telegraphy established. Then, in 1859, Bowman Lindsay demonstrated to the British Association his method of transmitting messages by means of magnetism through and across the water without submerged wires. In 1867 James Clerk Maxwell laid down the theory of electro-magnetism and predicted the existence of the electric waves that are now used in wireless telegraphy. Dolbear, of Tufts College, in 1836, patented a plan for establishing wireless communication by means of two insulated elevated plates, but there is no evidence that the method proposed by him effected the transmission of signals between stations separated by any distance. A year later Heinrich Rudolph Hertz discovered the progressive propagation of electro-magnetic action through space and accomplished the most valuable work in this period of speculation and experiment.
Just twenty years ago, at his father’s country home in Bologna, Guglielmo Marconi, then a lad just out of his ’teens, read of the experiments of Hertz and conceived the first wireless telegraph apparatus. This was completed some months later and a message in the Morse Code was transmitted a distance of three or four feet, the length of the table on which the apparatus rested.
Satisfied that he had laid the foundation of an epoch-making discovery young Marconi pursued his experiments and filed the first patent on the subject on June 2, 1896. Further experiments were carried on in London during that year and at the request of Sir William H. Preece, of the British Post Office, official tests were made, first over a distance of about 100 yards and later for one and three-quarter miles.
During the year following Mr. Marconi gave several demonstrations to the officials of the various European governments and communication was established up to 34 miles. In July of this year, 1897, the first commercial wireless telegraph company was incorporated in England and the first Marconi station was erected at the Needles, Isle of Wight.
On June 3, 1898, Lord Kelvin visited this station and sent the first paid Marconigram. A month later the events of the Kingstown Regatta in Dublin were reported by wireless telegraphy for a local newspaper from the steamer “Flying Huntress.” In August of that year the royal yacht “Osborn” was equipped with a wireless set, in order that Queen Victoria might communicate with the Prince of Wales, who was at Ladywood Cottage and suffering from the results of an accident to his knee. For sixteen days, constant and uninterrupted communication was maintained. Then on Christmas Eve was inaugurated the first lightship wireless service, messages being sent from the East Goodwin lightship to the lighthouse at South Foreland.
Three months later the first marine rescue was effected through this installation. The steamship “R. F. Matthews” ran into the lightship and lifeboats from the South Foreland station promptly responded to the wireless appeal for aid. The most important wireless event abroad during the year 1899 was the establishing of communication across the English Channel, a distance of thirty miles.
The American public next learned something of Marconi’s invention, for in September and October of that year wireless telegraphy was employed in reporting the International yacht races between the “Shamrock” and the “Columbia” for a New York newspaper. At the conclusions of the races, the naval authorities requested a series of trials, during which wireless messages were exchanged between the cruiser “New York” and the battleship “Massachusetts” up to a distance of about 36 miles. On leaving America, Marconi fitted the liner “St. Paul” with his apparatus and when 36 miles from the Needles Station, secured wireless reports of the war in South Africa. These were printed aboard the vessel in a leaflet called “The Transatlantic Times,” the first of the chain of wireless newspapers now published daily on practically all passenger steamships. Six field wireless sets were dispatched to South Africa about this time and were later of considerable service in the Boer War.
The year 1900 brought the first commercial wireless contracts. By agreement with the Norddeutscher Lloyd, Marconi apparatus was installed on a lightship, a lighthouse and aboard the liner “Kaiser Wilhelm der Grosse.” On July 4th the British Admiralty entered into a contract for the installation of Marconi apparatus on thirty-two warships and shore stations and the erection of the high power station at Poldhu was commenced.
WORLD WIDE USE OF THE WIRELESS
Work on similar station at Cape Cod was begun early in 1901 and on August 12th the famous Nantucket Island and Nantucket lightship stations opened to report incoming vessels by wireless. Heavy gales in September and November wrecked the masts at both Poldhu and Cape Cod stations and these were replaced by four wooden towers, 210 feet high. Important experimental work was then shifted to St. John’s, Newfoundland, and on December 12th and 13th, signals were received across the Atlantic from Poldhu. This to Marconi was a great achievement and the forerunner of the present day trans-atlantic service. But with the announcement that the long dreamt of feat had been accomplished a flood of vituperation from scientific men was let loose. It was nonsense; it was deliberate deception; the reading was in error, were among the comments. Another prank of the “young man with a box,” one scientist termed it. It is amusing now to recall this extraordinary treatment, but it was hardly so amusing to the young inventor, then in his twenty-seventh year.
But in spite of the skepticism, developments followed rapidly from then on and in 1902, the year in which the American Marconi Company was established, full recognition to wireless telegraphy was given by the various governments.
The wonderful growth of the Marconi system within the last twelve years is well known to all and does not require detailing. But in view of its youth as an industry and its inauspicious beginning, a glimpse into what the present day Marconi system comprises may be interesting.
More than 1800 ships are equipped with Marconi wireless and its shore stations are landmarks in practically every country on the globe.
Press and commercial messages are transmitted daily from continent to continent direct.
Shore to ship and ship to shore business each year runs into millions of words.
Marconi wireless within seventeen years, has become an absolute necessity in the maritime field, an invaluable aid in others. Regular communication has been established with icebound settlements and desert communities, and official running orders transmitted to moving railway trains. Its service is dependable under all conditions and embraces activities and locations inaccessible to any other telegraph system. Continuous service is maintained and wireless messages for all parts of the world at greatly reduced rates are received at any Western Union Office.
The direction finder and wireless compass are recent Marconi inventions.
A wide variety of types of Marconi equipment are designed for the merchant marine, warships, submarines, pleasure craft, motor cars and railroad trains; also portable signal corps sets, apparatus for aircraft, cavalry sets, knapsack sets and high-power installations for trans-ocean communication.