Part 12
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.
APPENDIX A
NEW DEVELOPMENTS OF THE TELEGRAPH
_By F.W. Lienan, Superintendent Tariff Bureau, Western Union Telegraph Company_
The invention of Samuel F.B. Morse is unique in this, that the methods and instruments of telegraph operation as he evolved them from his first experimental apparatus were so simple, and yet so completely met the requirements, that they have continued in use to the present day in practically their original form. But this does not mean that there has not been the same constant striving for betterment in this as in every other art. Many minds have, since the birth of the telegraph, occupied themselves with the problem of devising improved means of telegraphic transmission. The results have varied according to the point of view from which the subject was approached, but all, directly or indirectly, sought the same goal (the obvious one, since speed is the essence of telegraphy), to find the best means of sending more messages over the wire in a given time. It will readily suggest itself that the solution of this problem lies either in an arrangement enabling the wire to carry more than one message at once, or in some apparatus capable of transmitting messages over the wire more rapidly than can be done by hand, or in a combination of both these principles.
Duplex and quadruples operations are perhaps the most generally known methods by which increased utilization of the capacity of the line has been achieved. Duplex operation permits of the sending of two messages over one wire in opposite directions at the same time; and quadruples, the simultaneous transmission of four messages, two going in each direction. Truly a remarkable accomplishment; but, like many other things that have found their permanent place in daily use, become so familiar that we no longer pause to marvel at it. These expedients constitute a direct and very effective attack on the problem how to get more work out of the wire with the existing means of operation, and on account of their fundamental character and the important place which by reason thereof they have taken in the telegraphic art, are entitled to first mention.
The problem of increasing the rapidity of transmission has been met by various automatic systems of telegraphy, so called because they embody the idea of mechanical transmission with resulting gain in speed and other advantages. The number of these which have from time to time been devised is considerable. Not all have proven to be practicable, but those which have failed to prove in under actual operating conditions none the less display evidence of ingenuity which may well excite our admiration.
To mention one or two which may be interesting on account of the oddity of their method--there was, for instance, an early device, similar in principle to the calling apparatus of the automatic telephone, which involved the turning of a movable disk so that a projection on its circumference pointed successively to the letters to be transmitted. Experiments were made with ordinary metal type set up in a composing-stick, a series of brushes passing over the type faces and producing similar characters on a tape at the other end of the line. In another more recent ingenious device a pivoted mirror at the receiving end was so manipulated by the electrical impulses that a ray of light reflected from the surface of the mirror actually wrote the message upon sensitized paper, like a pencil, in a fair handwriting. In another the receiving apparatus printed vertical, horizontal, and slanting lines in such manner that they combined to make letters, rather angular, it is true, but legible.
These and other kindred devices are interesting as efforts to accomplish the direct production of legible messages. In experimental tests they performed their function successfully, and in some cases with considerable speed, but some of them required more than one line wire, some were too sensitive to disturbance by inductive currents and some developed other weaknesses which have prevented their incorporation in the actual operating machinery of to-day.
In the general development of the so-called automatic telegraph devices which have been or now are in practical operation, two lines have been pursued. One involves direct keyboard transmission; the other, the use at the sending end of a perforated tape capable of being run through a transmitting machine at high speed. One type of the former is the so-called step-by-step process, in which a revolving body in the transmitting apparatus, as, for instance, a cylinder provided with pegs placed at intervals around its circumference in spiral fashion, is arrested by the depression of the keys of the keyboard in such a way that a type wheel in the receiving apparatus at the distant end of the line prints the corresponding letter. This method was employed in the House and Phelps printing telegraphs operated by the Western Union Telegraph Company in its earlier days, and is to-day used in the operation of the familiar ticker. In another type of direct keyboard operation the manipulation of the keys transmits the impulses directly to the line and the receiving apparatus translates them by electrically controlled mechanical devices into printed characters in message form.
The systems best adapted to rapid telegraph work are predicated on the use of a perforated tape on which, by means of a suitable perforating apparatus, little round holes are produced in various groupings, each group, when the tape is passed through the transmitter, causing a certain combination of electrical impulses to pass over the wire. The transmitter as a rule consists of a mechanically or motor driven mechanism which causes the telegraph impulses to be transmitted to the line, and the combination and character of the impulses are determined by the tape perforations. The rapidity with which the tape may be driven through the transmitter makes very high speed operation possible. Of course it is necessary that there should be at the other end of the wire apparatus capable of receiving and recording the signals as speedily as they are sent.
As early as 1848 Alexander Bain perfected a system involving the use of the perforated transmitting tape; at the receiving station the messages were recorded in dots and dashes upon a chemically prepared strip of paper by means of iron pens, the metal of which was, through the combined action of the electrical current and the chemical preparation, decomposed, producing black marks in the form of dots and dashes upon the paper. The Bain apparatus was in actual operation in the younger days of the telegraph. Various systems, based on similar principles, involving tape transmission and the production of dots and dashes on a receiving tape, have from time to time been devised, but have generally not succeeded in establishing any permanent usefulness in competition with more effective instrumentalities which have been perfected.
The hardiest survivor of them is the Wheatstone apparatus, which has been in successful operation for years. Originally the perforating--or, to use the commonly current term, the punching--of the Wheatstone sending tape was accomplished by a mechanism equipped with three keys--one for the dot, one for the dash, and one for the space. The keys were struck with rubber-tipped mallets held in the hands of the operator and brought down with considerable force. Later this rather primitive perforator was supplanted by one equipped with a full keyboard on the order of a typewriter keyboard. At the receiving end of the line the messages are produced on a tape in dots and dashes of the Morse alphabet, and hence a further process of translation is necessary. This system has proven very useful, particularly in times of wire trouble and scarcity of facilities, when it is essential to move as many messages as possible over the available lines.
The schemes devised for combining automatic transmission by the perforated-tape method with direct production of the message at its destination in ordinary letters and figures, eliminating the intervening step of translation from Morse characters, have been many. Their individual enumeration is beyond the scope of the present discussion, and would in any event involve a wearisome exposition of their distinguishing technical features. Several of these systems are at present in practical and very effective operation.
One of the forerunners of the printing telegraph systems now in use was the Buckingham system, for many years employed by the Western Union Telegraph Company, but now for some time obsolete. The receiving mechanism of this system printed the messages on telegraph blanks placed upon a cylinder of just the right circumference to accommodate two telegraph blanks. The blanks were arranged in pairs, rolled into the form of a tube and placed around the cylinder. When two messages had been written a new pair of blanks had to be substituted. This was a rather awkward arrangement, but at a time when more highly developed apparatus had not been perfected it served its purpose to good advantage.
The printing telegraphs of to-day produce their messages by the direct operation of typewriting machines or mechanisms operating substantially in the same manner as the ordinary typewriting machine. The methods by which the electrical impulses coming over the line are transformed into mechanical operation of the typewriter keys, or what corresponds to the typewriter keys, vary. It would be difficult to describe how this function is performed without entering upon much detail of a highly technical character. Suffice it to say that means have been devised by which each combination of electrical impulses coming over the line wire causes a channel to be opened for the motor operation of the typewriting key-bar operating the corresponding letter upon the typewriter apparatus. These machines write the messages with proper arrangement of the date line, address, text, and signature, operating not only the type, but also the carriage shift and the line spacing as required. A further step in advance has been made by feeding the blanks into the receiving typewriter from a continuous roll, an attendant tearing the messages off as they are completed. The entire operation is automatic from beginning to end and capable of considerable speed.
There remained the problem of devising some means by which a number of automatic units could be operated over the same line at the same time. This is not by any means a new proposition. Here again various solutions have been offered by the scientists both of Europe and of this country, and different systems designed to accomplish the desired object have been placed in operation. One of the most recent, and we believe the most efficient so far developed, is the so-called multiplex printer system, devised by the engineers of the Western Union Telegraph Company and now being extensively used by that company. Perhaps the best picture of what is accomplished by this system can be given by an illustration. Let us assume a single wire between New York and Chicago. At the New York end there are connected with this wire four combined perforators and transmitters, and four receiving machines operating on the typewriter principle. At the Chicago end the wire is connected with a like number of sending and receiving machines. All these machines are in simultaneous operation; that is to say, four messages are being sent from New York to Chicago, and four messages are being sent from Chicago to New York, all at the same time and over a single wire, and the entire process is automatic. The method by which eight messages can be sent over a single wire at the same time without interfering with one another cannot readily be described in simple terms. It may give some comprehension of the underlying principle to say that the heart of the mechanism is in two disks at each end of the line, which are divided into groups of segments insulated from each other, each group being connected to one of the sending or receiving machines, respectively. A rotating contact brush connected to the line wire passes over the disk, so that, as it comes into contact with each segment, the line wire is connected in turn with the channel leading to the corresponding operating unit. The brushes revolve in absolute unison of time and position. To use the same illustration as before, the brush on the Chicago disk and the brush on the New York disk not only move at exactly the same speed, but at any given moment the two brushes are in exactly the same position with regard to the respective group of segments of both disks. If we now conceive of these brushes passing over the successive segments of the disks at a very great rate of speed, it may be understood that the effect is that the electrical impulses are distributed, each receiving machine receiving only those produced by the corresponding sending machine at the other end. In other words, each of the sets of receiving and sending apparatus really gets the use of the line for a fraction of the time during each revolution of the brushes of the distributer or disk mechanism. The multiplex automatic circuits are being extended all over the country and are proving extremely valuable in handling the constantly growing volume of telegraph traffic.
What has thus been achieved in developing the technical side of telegraph operation must be attributed in part to that impulse toward improvement which is constantly at work everywhere and is the most potent factor in the progress of all industries, but in large measure it is the reflex of the growing--and recently very rapidly growing--demands which are made upon the telegraph service. Emphasis is placed on the larger ratio of growth in this demand in recent years because it is peculiarly symptomatic of a noticeably wider realization of the advantages which the telegraph offers as an effective medium for business and social correspondence than has heretofore been in evidence. It means that we have graduated from that state of mind which saw in the telegraph something to be resorted to only under the stress of emergency, which caused many good people to associate a telegram with trouble and bad news and sudden calamity. There are still some dear old ladies who, on receipt of a telegram, make a rapid mental survey of the entire roster of their near and distant relatives and wonder whose death or illness the message may announce before they open the fateful envelope, only to find that up-to-date Cousin Mary, who has learned that the telegraph is as readily used as the mail and many times more rapid and efficient, wants to know whether they can come out for the week-end. When Cousin Mary of to-day wants to know, she wants to know right away--not only that she has her arrangements to make, but also because she just does not propose to wait a day or two to get a simple answer to a simple question.
Therein she embodies the spirit of the times. Our ancestors were content to jog along for days in a stuffy stage-coach; we complain that the train which accomplishes the same distance in a few hours is too slow. We act more quickly; we think more quickly. We have to if we want to keep within earshot of the band.