XX
TELEPHONING THROUGH SPACE
The Search for the Wireless Telephone—Early Successes—Carty and
His Assistants Seek the Wireless Telephone—The Task Before Them—De
Forest's Amplifier—Experimental Success Achieved—The
Test—Honolulu and Paris Hear Arlington—The Future.
No sooner had Marconi placed the wireless telegraph at the service of the world than men of science of all nations began the search for the wireless telephone. But the vibrations necessary to reproduce the sound of the human voice are so infinitely more complex than those which will suffice to carry signals representing the dots and dashes of the telegraph code that the problem long defied solution. Scientists attacked the problem with vigor, and various means of wireless telephony were developed, without any being produced which were effective over sufficient ranges to make them really useful.
Probably the earliest medium chosen to carry wireless speech was light rays. A microphone transmitter was arranged so that the vibrations of the voice would affect the stream of gas flowing in a sensitive burner. The flame was thus thrown into vibrations corresponding to the vibrations of sound. The rays from this flame were then directed by mirrors to a distant receiving station and there concentrated on a photo-electric selenium cell, which has the strange property of varying its resistance according to the illumination. Thus a telephone receiver arranged in series with it was made to reproduce the sounds.
This strange, wireless telephone was so arranged that a search-light beam could be used for the light path, and distances up to three miles were covered. Even with this limited range the search-light telephone had certain advantages. Its message could be received only by those in the direct line of the light. Neither did it require aerial masts or wires and a trained telegrapher who could send and receive the telegraph code. It was put to some use between battle-ships and smaller craft lying within a radius of a few miles. The sensitive selenium cell proved unreliable, however, and this means of communication was destined to failure.
The experimenters realized that future success lay in making the ether carry telephonic currents as it carried telegraphic currents. They succeeded in establishing communication without wires, using the same antenna as in wireless telegraphy, and the principles determined are those used in the wireless telephone of to-day. The sending apparatus was so arranged that continuous oscillations are set up in the ether, either by a high-frequency machine or from an electric arc. Where set up by spark discharges the spark frequency must be above twenty thousand per second. This unbroken wave train does not affect the telephone and is not audible in a telephone receiver inserted in the radio receiving circuit. But when a microphone transmitter is inserted in the sending circuit, instead of the make-and-break key used for telegraphy, the waves of the voice, thrown against the transmitter in speaking, break up the waves so that the telephone receiver in the receiving circuit will reproduce sound. Here was and is the wireless telephone. Marconi and many other scientists were able to operate it successfully over comparatively short distances, and were busily engaged in extending its range and improving the apparatus. One great difficulty involved was in increasing the power of the sending apparatus. Greater range has been secured in wireless telegraphy by using stronger sending currents. But the delicate microphone would not carry these stronger currents. Increased sensitiveness in the receiving apparatus was also necessary.
Not content with their accomplishments in increasing the scope of the wire telephone, the engineers of the Bell organization, headed by John J. Carty, turned their attention to the wireless transmission of speech. Determined that the existing telephone system should be extended and supplemented in every useful way, they attacked the problem with vigor. It was a problem that had long baffled the keenest of European scientists, including Marconi himself, but that did not deter Carty and his associates. They were determined that the glory of spanning the Atlantic by wireless telephone should come to America and American engineers. They wanted history to record the wireless telephone as an American achievement along with the telegraph and the telephone.
The methods used in achieving the wireless telephone were widely different from those which brought forth the telegraph and the telephone. Times had changed. Men had found that it was more effective to work together through organizations than to struggle along as individuals. The very physical scope of the undertakings made the old methods impracticable. One cannot perfect a transcontinental telephone line nor a transatlantic wireless telephone in a garret. And with a powerful organization behind them it was not necessary for Carty and his associates to starve and skimp through interminable years, handicapped by the inadequate equipment, while they slowly achieved results. This great organization, working with modern methods, produced the most wonderful results with startling rapidity.
Important work had already been done by Marconi, Fessenden, De Forest, and others. But their results were still incomplete; they could not talk for any considerable distance. Carty organized his staff with care, Bancroft Gerhardi, Doctor Jewett, H.D. Arnold, and Colpitts being prominent among the group of brilliant American scientists who joined with Carty in his great undertaking. While much had been accomplished, much still remained to be done, and the various contributions had to be co-ordinated into a unified, workable whole. In large part it was Carty's task to direct the work of this staff and to see that all moved smoothly and in the right direction. Just as the telephone was more complex than the telegraph, and the wireless telegraph than the telephone, so the apparatus used in wireless telephony is even more complex and technical. Working with the intricate mechanisms and delicate apparatus, one part after another was improved and adapted to the task at hand.
To the devices of Carty and his associates was added the extremely delicate detector that was needed. This was the invention of Dr. Lee de Forest, an American inventor and a graduate of the Sheffield Technical School of Yale University. De Forest's contribution was a lamp instrument, a three-step audion amplifier. This is to the wireless telephone what the coherer is to the wireless telegraph. It is so delicate that the faintest currents coming through the ether will stimulate it and serve to set in motion local sources of electrical energy so that the waves received are magnified to a point where they will produce sound.
By the spring of 1915, but a few months after the transcontinental telephone line had been put in operation, Carty had his wireless telephone apparatus ready for extended tests. A small experimental tower was set up at Montauk Point, Long Island, and another was borrowed at Wilmington, Delaware. The tests were successful, and the experimenters found that they could talk freely with each other. Soon they talked over a thousand miles, from the tower at Montauk Point to another at St. Simon's Island, Georgia. This in itself was a great achievement, but the world was not told of it. "Do it first and then talk about it" is the maxim with Theodore Vail and his telephone men. This was but a beginning, and Carty had far more wonderful things in mind.
It was on the 29th of September, 1915, that Carty conducted the demonstrations which thrilled the world and showed that wireless telephony was an accomplished fact. Sitting in his office in New York, President Theodore Vail spoke into his desk telephone of the familiar type. The wires carried his words to the towers of the Navy wireless station at Arlington, Virginia, where they were delivered to the sending apparatus of the wireless telephone. Leaping into space, they traveled in every direction through the ether. The antenna of the wireless station at Mare Island, California, caught part of the waves and they were amplified so that John Carty, sitting with his ear to the receiver, could hear the voice of his chief. Carty and his associates had not only developed a system which made it possible to talk across the continent without wires, but they had made it possible to combine wire and wireless telegraphy. He and Vail talked with each other freely and easily, while the naval officers who verified the tests marveled.
But even more wonderful things were to come. Early in the morning of the next day other messages were sent from the Arlington tower, and these messages were heard by Lloyd Espenschied, one of Carty's engineers, who was stationed at the wireless station at Pearl Harbor, near Honolulu, Hawaii. The distance covered was nearly five thousand miles, and half of it was across land, which is the more remarkable as the wireless does not operate so readily over land as over water. The distance covered in this test was greater than the distance from Washington to London, Paris, Berlin, Vienna, or Petrograd. The successful completion of this test meant that the capitals of the great nations of the world might communicate, might talk with one another, by wireless telephone. Only a receiving set had been installed at Hawaii, so that it was not possible for Espenschied to reply to the message from Arlington, and it was not until his message came by cable that those at Arlington knew that the words they had spoken had traveled five thousand miles. Other receiving sets had been located at San Diego and at Darien on the Isthmus of Panama, and at these points also the words were distinctly heard.
By the latter part of October all was in readiness for a transatlantic test, and on the 20th of October American engineers, with American apparatus installed at the great French station at the Eiffel Tower, Paris, heard the words spoken at Arlington, Virginia. Carty and his engineers had bridged the Atlantic for the spoken word. Because of war-time conditions it was not possible to secure the use of the French station for an extended test, but the fact was established that once the apparatus is in place telephonic communication between Europe and America may he carried on regularly.
The apparatus used as developed by the engineers of the Bell system was in a measure an outgrowth of their work with the long-distance telephone. Wireless telephony, despite the wonders it has already accomplished, is still in its infancy. With more perfect apparatus and the knowledge that comes with experience we may expect that speech will girdle the earth.
It is natural that one should wonder whether the wireless telephone is destined to displace our present apparatus. This does not seem at all probable. In the first place, wireless telephony is now, and probably always will be, very expensive. Where the wire will do it is the more economical. There are many limitations to the use of the other for talking purposes, and it cannot be drawn upon too strongly by the man of science. It will accomplish miracles, but must not be overtaxed. Millions of messages going in all directions, crossing and recrossing one another, as is done every day by wire, are probably an impossibility by wireless telephony. Weird and little-understood conditions of the ether, static electricity, radio disturbances, make wireless work uncertain, and such a thing as twenty-four-hour service, seven days in the week, can probably never be guaranteed. In radio communication all must use a common medium, and as its use increases, so also do the difficulties. The privacy of the wire is also lacking with the wireless telephone.
But because a way was found to couple the wireless telephone with the wire telephone, the new wonder has great possibilities as a supplement to our existing system. Before so very long it may be possible for an American business man sitting in his office to call up and converse with a friend on a liner crossing the Atlantic. The advantages of speaking between ship and ship as an improvement over wireless telegraphy in time of need are obvious. A demonstration of the part this great national telephone system would play in the country's defense in case of attack was held in May of 1916. The Navy Department at Washington was placed in communication with every navy-yard and post in the United States, so that the executive officers could instantly talk with those in charge of the posts throughout the country. The wireless telephone was used in addition to the long distance, and Secretary of the Navy Daniels, sitting at his desk at Washington, talked with Captain Chandler, who was at his station on the bridge of the U.S.S. New Hampshire at Hampton Roads.
Whatever the future limitations of wireless telephony, there is no doubt as to the place it will take among the scientific accomplishments of the age. Merely as a scientific discovery or invention, it ranks among the wonders of civilization. Much as the tremendous leap of human voice across the line from New York to San Francisco appealed to the mind, there is something infinitely more fascinating in this new triumph of the engineer. The human mind can grasp the idea of the spoken word being carried along wires, though that is difficult enough, but when we try to understand its flight through space we are faced with something beyond the comprehension of the layman and almost past belief.
We have seen how communication has developed, very slowly at first, and then, as electricity was discovered, with great rapidity until man may converse with man at a distance of five thousand miles. What the future will bring forth we do not know. The ether may be made to accomplish even more wonderful things as a bearer of intelligence. Though we cannot now see how it would be possible, the day may come when every automobile and aeroplane will be equipped with its wireless telephone, and the motorist and aviator, wherever they go, may talk with anyone anywhere. The transmission of power by wireless is confidently predicted. Pictures have been transmitted by telegraph. It may be possible to transmit them by wireless. Then some one may find out how to transmit moving pictures through the ether. Then one might sit and see before him on a screen a representation of what was then happening thousands of miles away, and, listening through a telephone, hear all the sounds at the same place. Wonders that we cannot even now imagine may lie before us.