Chapter 2

While the British navy used flashing lights for night signals, the United States and most other navies adopted a system of fixed colored lights. The system in use in the United States Navy is known as the Ardois system. In this system the messages are sent by four lights, usually electric, which are suspended from a mast or yard-arm. The lights are manipulated by a keyboard situated at a convenient point on the deck. A red lamp is flashed to indicate a dot in the Morse code, while a white lamp indicates a dash. The Ardois system is also used by the Army. The perfection of wireless telegraphy has caused the Ardois and other signal systems depending upon sight or sound to be discarded in all but exceptional cases. The wig-wag and similar systems will probably never be entirely displaced by even such superior systems as wireless telegraphy. The advantage of the wig-wag lies in the fact that no apparatus is necessary and communication may thus be established for short distances almost instantly. Its disadvantages are lack of speed, impenetrability to dust, smoke, and fog, and the short ranges over which it may be operated.

There is another form of sound-signaling which, though it has been developed in recent years, may properly be mentioned in connection with earlier signal systems of similar nature. This is the submarine signal. We have noted that much attention was paid to communication by sound-waves through the medium of the air from the earliest times. It was not until the closing years of the past century, however, that the superior possibilities of water as a conveyer of sound were recognized.

Arthur J. Mundy, of Boston, happened to be on an American steamer on the Mississippi River in the vicinity of New Orleans. It was rumored that a Spanish torpedo-boat had evaded the United States war vessels and made its way up the great river. The general alarm and the impossibility of detecting the approach of another vessel set Mundy thinking. It seemed to him that there should be some way of communicating through the water and of listening for sounds underwater. He recalled his boyhood experiments in the old swimming-hole. He remembered how distinctly the sound of stones cracked together carried to one whose ears were beneath the surface. Thus the idea of underwater signaling was born.

Mundy communicated this idea to Elisha Gray, and the two, working together, evolved a successful submarine signal system. It was on the last day of the nineteenth century that they were able to put their experiments into practical working form. Through a well in the center of the ship they suspended an eight-hundred-pound bell twenty feet beneath the surface of the sea. A receiving apparatus was located three miles distant, which consisted simply of an ear-trumpet connected to a gas-pipe lowered into the sea. The lower end of the pipe was sealed with a diaphragm of tin. When submerged six feet beneath the surface the strokes of the bell could be heard. Then a special electrical receiver of extreme sensitiveness, known as a microphone, was substituted and connected at the receiving station with an ordinary telephone receiver. With this receiving apparatus the strokes of the bell could be heard at a distance of over ten miles.

This system has had a wide practical application for communication both between ship and ship and between ship and shore. Most transatlantic ships are now equipped with such a system. The transmitter consists of a large bell which is actuated either by compressed air or by an electro-magnetic system. This is so arranged that it may be suspended over the side of the ship and lowered well beneath the surface of the water. The receivers consist of microphones, one on each side of the ship. The telephone receivers connected to the two microphones are mounted close together on an instrument board on the bridge of the ship. The two instruments are used when it is desired to determine the direction from which the signals come. If the sound is stronger in the 'phone on the right-hand side of the ship the commander knows that the signals are coming from that direction. If the signals are from a ship in distress he may proceed toward it by turning his vessel until the sound of the signal-bell is equal in the two receivers. The ability to determine the direction from which the signal comes is especially valuable in navigating difficult channels in foggy weather. Signal-bells are located near lighthouses and dangerous reefs. Each calls its own number, and the vessel's commander may thus avoid obstructions and guide the ship safely into the harbor. The submarine signal is equally useful in enabling vessels to avoid collision in fogs. Because water conducts sound much better than air, submarine signals are far better than the fog-horn or whistles.

The submarine signal system has also been applied to submarine war-ships. By this means alone may a submarine communicate with another, with a vessel on the surface, or with a shore station.

An important and interesting adaptation of the marine signal was made to meet the submarine warfare of the great European conflict. At first it seemed that battle-ship and merchantman could find no way to locate the approach of an enemy submarine. But it was found that by means of the receiving apparatus of the submarine telephone an approaching submarine could be heard and located. While the sounds of the submarine's machinery are not audible above the water, the delicate microphone located beneath the water can detect them. Hearing a submarine approaching beneath the surface, the merchantman may avoid her and the destroyers and patrol-boats may take means to effect her capture.

III

FORERUNNERS OF THE TELEGRAPH

From Lodestone to Leyden Jar--The Mysterious "C.M."--Spark and Frictional Telegraphs--The Electro-magnet--Davy and the Relay System.

The thought and effort directed toward improving the means of communication brought but small results until man discovered and harnessed for himself a new servant--electricity. The story of the growth of modern means of communication is the story of the application of electricity to this particular one of man's needs. The stories of the Masters of Space are the stories of the men who so applied electricity that man might communicate with man.

Some manifestations of electricity had been known since long before the Christian era. A Greek legend relates how a shepherd named Magnes found that his crook was attracted by a strange rock. Thus was the lodestone, the natural magnetic iron ore, discovered, and the legend would lead us to believe that the words magnet and magnetism were derived from the name of the shepherd who chanced upon this natural magnet and the strange property of magnetism.

The ability of amber, when rubbed, to attract straws, was also known to the early peoples. How early this property was found, or how, we do not know. The name electricity is derived from _elektron_, the Greek name for amber.

The early Chinese and Persians knew of the lodestone, and of the magnetic properties of amber after it has been rubbed briskly. The Romans were familiar with these and other electrical effects. The Romans had discovered that the lodestone would attract iron, though a stone wall intervened. They were fond of mounting a bit of iron on a cork floating in a basin of water and watch it follow the lodestone held in the hand. It is related that the early magicians used it as a means of transmitting intelligence. If a needle were placed upon a bit of cork and the whole floated in a circular vessel with the alphabet inscribed about the circle, one outside the room could cause the needle to point toward any desired letters in turn by stepping to the proper position with the lodestone. Thus a message could be sent to the magician inside and various feats of magic performed. Our own modern magicians are reported as availing themselves of the more modern applications of electricity in somewhat similar fashion and using small, easily concealed wireless telegraph or telephone sets for communication with their confederates off the stage.

The idea of encircling a floating needle with the alphabet was developed into the sympathetic telegraph of the sixteenth century, which was based on a curious error. It was supposed that needles which had been touched by the same lodestone were sympathetic, and that if both were free to move one would imitate the movements of another, though they were at a distance. Thus, if one needle were attracted toward one letter after the other, and the second similarly mounted should follow its movements, a message might readily be spelled out. Of course the second needle would not follow the movements of the first, and so the sympathetic telegraph never worked, but much effort was expended upon it.

In the mean time others had learned that many substances besides amber, on being rubbed, possessed magnetic properties. Machines by which electricity could be produced in greater quantities by friction were produced and something was learned of conductors.

Benjamin Franklin sent aloft his historic kite and found that electricity came down the silken cord. He demonstrated that frictional and atmospheric electricity are the same. Franklin and others sent the electric charge along a wire, but it did not occur to them to endeavor to apply this to sending messages.

Credit for the first suggestion of an electric telegraph must be given to an unknown writer of the middle eighteenth century. In the _Scots Magazine_ for February 17, 1755, there appeared an article signed simply, "C.M.," which suggested an electric telegraph. The writer's idea was to lay an insulated wire for each letter of the alphabet. The wires could be charged from an electrical machine in any desired order, and at the receiving end would attract disks of paper marked with the letter which that wire represented, and so any message could be spelled out. The identity of "C.M." has never been established, but he was probably Charles Morrison, a Scotch surgeon with a reputation for electrical experimentation, who later emigrated to Virginia. Of course "C.M.'s" telegraph was not practical, because of the many wires required, but it proved to be a fertile suggestion which was followed by many other thinkers. One experimenter after another added an improvement or devised a new application.

A French scientist devised a telegraph which it is suspected might have been practical, but he kept his device secret, and, as Napoleon refused to consider it, it never was put to a test. An Englishman devised a frictional telegraph early in the last century and endeavored to interest the Admiralty. He was told that the semaphore was all that was required for communication. Another submitted a similar system to the same authorities in 1816, and was told that "telegraphs of any kind are now wholly unnecessary." An American inventor fared no better, for one Harrison Gray Dyar, of New York, was compelled to abandon his experiments on Long Island and flee because he was accused of conspiracy to carry on secret communication, which sounded very like witchcraft to our forefathers. His telegraph sent signals by having the electric spark transmitted by the wire decompose nitric acid and so record the signals on moist litmus paper. It seems altogether probable that had not the discovery of electro-magnetism offered improved facilities to those seeking a practical telegraph, this very chemical telegraph might have been put to practical use.

In the early days of the nineteenth century the battery had come into being, and thus a new source of electric current was available for the experimenters. Coupled with this important discovery in its effect upon the development of the telegraph was the discovery of electro-magnetism. This was the work of Hans Christian Oersted, a native of Denmark. He first noticed that a current flowing through a wire would deflect a compass, and thus discovered the magnetic properties of the electric current. A Frenchman named Ampère, experimenting further, discovered that when the electric current is sent through coils of wire the magnetism is increased.

The possibility of using the deflection of a magnetic needle by an electric current passing through a wire as a means of conveying intelligence was quickly grasped by those who were striving for a telegraph. Experiments with spark and chemical telegraphs were superseded by efforts with this new discovery. Ampère, acting upon the suggestion of La Place, an eminent mathematician, published a plan for a feasible telegraph. This was later improved upon by others, and it was still early in the nineteenth century that a model telegraph was exhibited in London.

About this time two professors at the University of Göttingen were experimenting with telegraphy. They established an experimental line between their laboratories, using at first a battery. Then Faraday discovered that an electric current could be generated in a wire by the motion of a magnet, thus laying the basis for the modern dynamo. Professors Gauss and Weber, who were operating the telegraph line at Göttingen, adapted this new discovery to their needs. They sent the message by moving a magnetic key. A current was thus generated in the line, and, passing over the wire and through a coil at the farther end, moved a magnet suspended there. The magnet moved to the right or left, depending on the direction of the current sent through the wire. A tiny mirror was mounted on the receiving magnet to magnify its movement and so render it more readily visible.

One Steinheil, of Munich, simplified it and added a call-bell. He also devised a recording telegraph in which the moving needle at the receiving station marked down its message in dots and dashes on a ribbon of paper. He was the first to utilize the earth for the return circuit, using a single wire for despatching the electric current used in signaling and allowing it to return through the ground.

In 1837, the same year in which Wheatstone and Morse were busy perfecting their telegraphs, as we shall see, Edward Davy exhibited a needle telegraph in London. Davy also realized that the discoveries of Arago could be used in improving the telegraph and making it practical. Arago discovered that the current passing through a coil of wire served to magnetize temporarily a piece of soft iron within it. It was this principle upon which Morse was working at this time. Davy did not carry his suggestions into effect, however. He emigrated to Australia, and the interruption in his experiments left the field open for those who were finally to bring the telegraph into usable form. Davy's greatest contribution to telegraphy was the relay system by which very weak currents could call into play strong currents from a local battery, and so make the signals apparent at the receiving station.

IV

INVENTIONS OF SIR CHARLES WHEATSTONE

Wheatstone and His Enchanted Lyre--Wheatstone and Cooke--First Electric Telegraph Line Installed--The Capture of the "Kwaker"--The Automatic Transmitter.

Before we come to the story of Samuel F.B. Morse and the telegraph which actually proved a commercial success as the first practical carrier of intelligence which had been created for the service of man, we should pause to consider the achievements of Charles Wheatstone. Together with William Fothergill Cooke, another Englishman, he developed a telegraph line that, while it did not attain commercial success, was the first working telegraph placed at the service of the public.

Charles Wheatstone was born near Gloucester in 1802. Having completed his primary schooling, Charles was apprenticed to his uncle, who was a maker and seller of musical instruments. He showed little aptitude either in the workshop or in the store, and much preferred to continue the study of books. His father eventually took him from his uncle's charge and allowed him to follow his bent. He translated poetry from the French at the age of fifteen, and wrote some verse of his own. He spent all the money he could secure on books. Becoming interested in a book on Volta's experiments with electricity, he saved up his coppers until he could purchase it. It was in French, and he found the technical descriptions rather too difficult for his comprehension, so that he was forced to save again to buy a French-English dictionary. With the aid of this he mastered the volume.

Immediately his attention was turned toward the wonders of the infant science of electricity, and he eagerly endeavored to perform the experiments described. Aided by his older brother, he set to work on a battery as a source of current. Running short of funds with which to purchase copper plates, he again began to save his pennies. Then the idea occurred to him to use the pennies themselves, and his first battery was soon complete.

He continued his experiments in various fields until, at the age of nineteen, he first brought himself to public notice with his enchanted lyre. This he placed on exhibition in music-shops in London. It consisted of a small lyre suspended from the ceiling which gave forth, in turn, the sounds of various musical instruments. Really the lyre was merely a sounding-box, and the vibrations of the music were conveyed from instruments, played in the next room, to the lyre through a steel rod. The young man spent much time experimenting with the transmission of sound. Having conveyed music through the steel rod to his enchanted lyre, much to the mystification of the Londoners, he proposed to transmit sounds over a considerable distance by this method. He estimated that sound could be sent through steel rods at the rate of two hundred miles a second and suggested the use of such a rod as a telegraph between London and Edinburgh. He called his arrangement a telephone.

A scientific writer of the day, commenting in a scientific journal on the enchanted lyre which Wheatstone had devised, suggested that it might be used to render musical concerts audible at a distance. Thus an opera performed in a theater might be conveyed through rods to other buildings in the vicinity and there reproduced. This was never accomplished, and it remained for our own times to accomplish this and even greater wonders.

Wheatstone also devised an instrument for increasing feeble sound, which he called a microphone. This consisted of a pair of rods to convey the sound vibrations to the ears, and does not at all resemble the modern electrical microphone. Other inventions in the transmission and reproduction of sound followed, and he devoted no little attention to the construction of improved musical instruments. He even made some efforts to produce a practical talking-machine, and was convinced that one would be attained. At thirty-two he was widely famed as a scientist and had been made a professor of experimental physics in King's College, London. His most notable work at this time was measuring the speed of the electric current, which up to that time had been supposed to be instantaneous.

By 1835 Wheatstone had abandoned his plans for transmitting sounds through long rods of metal and was studying the telegraph. He experimented with instruments of his own and proposed a line across the Thames. It was in 1836 that Mr. Cooke, an army officer home on leave, became interested in the telegraph and devoted himself to putting it on a working basis. He had already exhibited a crude set when he came to Wheatstone, realizing his own lack of scientific knowledge. The two men finally entered into partnership, Wheatstone contributing the scientific and Cooke the business ability to the new enterprise. The partnership was arranged late in 1837, and a patent taken out on Wheatstone's five-needle telegraph.

In this telegraph a magnetic needle was located within a loop formed by the telegraph circuit at the receiving end. When the circuit was closed the needle was deflected to one side or the other, according to the direction of the current. Five separate circuits and needles were used, and a variety of signals could thus be sent. Five wires, with a sixth return wire, were used in the first experimental line erected in London in 1837. So in the year when Morse was constructing his models Wheatstone and Cooke were operating an experimental line, crude and impracticable though it was, and enjoying the sensations of communicating with each other at a distance.

In 1841 the telegraph was placed on public exhibition at so much a head, but it was viewed as an entertaining novelty without utility by the public at large. After many disappointments the inventors secured the cooperation of the Great Western Railroad, and a line was erected for a distance of thirteen miles. But the public would not patronise the line until its utility was strikingly demonstrated by the capture of the "Kwaker."

Early one morning a woman was found dead in her home in the suburbs of London. A man had been observed leaving the house, and his appearance had been noted. Inquiries revealed that a man answering his description had left on the slow train for London. Without the telegraph he could not have been apprehended. But the telegraph was available at this point, and his description was telegraphed ahead and the police in London were instructed to arrest him upon his arrival. "He is dressed as a Quaker," ran the message. There was no Q in the alphabet of-the five-needle instrument, and so the sender spelled Quaker, Kwaker. The clerk at the receiving end could not-understand the strange word, and asked to have it repeated again and again. Finally some one suggested that the message be completed and the whole was then deciphered. When the man dressed as a Quaker stepped from the slow train on his arrival at London the police were awaiting him; he was arrested and eventually confessed the murder. The news of this capture and the part the telegraph played gave striking proof of the utility of the new invention, and public skepticism and indifference were overcome.

By 1845 Wheatstone had so improved his apparatus that but one wire was required. The single-needle instrument pointed out the letters on the dial around it by successive deflections in which it was arranged to move, step by step, at the will of the sending station. The single-needle instrument, though generally displaced by Morse's telegraph, remained in use for a long time on some English lines. Wheatstone had also invented a type-printing telegraph, which he patented in 1841. This required two circuits.

With a working telegraph attained, the partners became involved in an altercation as to which deserved the honor of inventing the same. The quarrel was finally submitted to two famous scientists for arbitration. They reported that the telegraph was the result of their joint labors. To Wheatstone belongs the credit for devising the apparatus; to Cooke for introducing it and placing it before the public in working form. Here we see the combination of the man of science and the man of business, each contributing needed talents for the establishment of a great invention on a working basis.

Wheatstone's researches in the field of electricity were constant. In 1840 he devised a magnetic clock and proposed a plan by which many clocks, located at different points, could be set at regular intervals with the aid of electricity. Such a system was the forerunner of the electrically wound and regulated clocks with which we are now so familiar. He also devised a method for measuring the resistance which wires offer to the passage of an electric current. This is known as Wheatstone's bridge and is still in use in every electrical and physical laboratory. He also invented a sound telegraph by which signals were transmitted by the strokes of a bell operated by the current at the receiving end of the circuit.