Part 17

He next sent a boy to buy a reel of cotton, and told his assistants he was going to see what a carbonized thread would do. They looked doubtful, but began the experiment. A short piece of the thread was bent in the form of a hairpin, laid in a nickel mould and securely clamped, and then put in a muffle furnace, where it was kept for five hours. Then it was taken out and allowed to cool. The mould was opened and the carbonized thread removed. It instantly broke. Another thread was put through the same process. As soon as it was taken from the mould it broke. Then a battle began that lasted for two days and two nights, the object of which was to get a carbonized thread that would not break. Edison wanted that thread because it contained no air, and might stand a greater current than the lampblack. Finally they took from the mould an unbroken thread, but as they tried to fasten it to the conducting wire it broke into pieces. Only on the night of the third day of their work, in all which time they had taken no rest, did they get a thread safely into the lamp, exhaust the air, and turn on the current. A clear, soft light resulted, and they knew that they had solved the problem of the incandescent light.

Edison and Bachelor watched that light for hours. They had turned on a small current at the start, to test the strength of the filament, but as it stood it, they turned on a greater and greater current until the thread was bearing a heat that would have instantly melted the platinum wire. The cotton thread glowed for forty-five hours, and then suddenly went out. The two watchers ended their long vigil, exhausted, but very happy. They knew that they had found the light that was to be the main illumination for the world.

But Edison realized that he had not yet found the ideal filament. The cotton thread had only lasted forty-five hours, and he wanted one that would burn for a hundred hours or longer. He wanted a more homogeneous material than thread, and he began to try carbonizing everything he could lay his hands on, straw, paper, cardboard, splinters of wood. He found that the cardboard stood the current better than the cotton thread, but even that did not burn long enough. Then he happened upon a bamboo fan, tore off the rim, and tried that. It made a filament that gave better results than any of the others.

Now he began his exhaustive study of bamboo. He learned that there were more than twelve hundred known varieties of bamboo. He wanted to find the most homogeneous variety. He sent out a number of men to hunt this bamboo, and it is said that the search cost nearly $100,000. Six thousand specimens of bamboo were carbonized, and he found three kinds of bamboo and one of cane that gave almost the result he wanted. All of these grew in a region near the Amazon, and were hard to get on account of malarial conditions. But at last he discovered the bamboo species that suited him, and he was ready to give his new light to the world.

The world was waiting for it. Scientists and the press reported his invention everywhere. He hung a row of lamps from the trees at Menlo Park, and the thousands who came to see them wondered when they found they could burn day and night for longer than a week. The lamps were small and finely made, they could be lighted or extinguished by simply pressing a button, and the cost of making them was slight. The last doubters surrendered, and admitted that Edison had given the world a new light, and one which was not simply a scientific marvel, but was eminently practical and useful.

But Edison is never satisfied with what he has done in any line; he must try to increase the service each invention gives. Therefore he now conceived the idea of having a central station from which every one might obtain electric light as they had formerly obtained gas. There were gigantic difficulties in the way of such an undertaking. Hardly any one outside of Edison’s own laboratory knew anything about electric lighting, and there were only a few of them who could be trusted to put a carbon filament in an exhausted globe.

He went about this new development in the most methodical way. He got an insurance map of New York City, and studied the business section from Wall to Canal Streets and from Broadway over to the East River. He knew where every elevator shaft and boiler and fire-wall was, and also how much gas each resident used and what he paid for it. This last he learned by hiring men to walk through the district at two o’clock in the afternoon and note how many gas lights were burning, then to make the rounds again at three, and again at four, and so on into the hours of the next morning.

With the field carefully examined he formed the New York Edison Illuminating Company, and had his assistants take charge of factories for making lamps, dynamos, sockets, and the other parts necessary for his lights. It was very difficult to get the land he wanted for his central station, but he finally bought two old buildings on Pearl Street for $150,000. He had little room space and he wanted to get a big output of electricity. So he decided to get a high-speed engine. They were practically unknown then, and when he went to an engine builder and said that he wanted a 150 horse-power engine that would run 700 revolutions per minute he was told it was impossible. But he found a man to build one for him, and set it up in the shop at Menlo Park. The shop was built on a shale hill, and when the engine was started the whole hill shook with the high speed revolutions. After some experimenting and changing they got the power that Edison wanted, and he ordered six more engines like the first.

In the meantime workmen had been busy digging ditches and laying mains through the district that Edison intended to light. The engines were set up in the central station and tried out. Then the troubles began. The engines would not run evenly, one would stop and another go dashing on at a tremendous speed. Edison tried a dozen different plans before he brought anything like order out of that engine chaos. Finally he had some engines built to run at 350 revolutions and give 175 horse-power, and these proved what was required. September 4, 1882, he turned the current on to the mains for the needed light service, and it stayed on with only one short stoppage for eight years.

In this way Edison invented the electric light and evolved the central station that should provide the current wherever it was needed. At the same time he had worked out countless adjuncts to it, the use of the fine copper thread to serve as a fuse wire and prevent short-circuiting, the meter, consisting of a small glass cell, containing a solution in which two plates of zinc are placed, and which shows how much current is supplied, the weighing voltameter, and other instruments for estimating the current, and improvements on the motors and engines. There was no field remotely connected with electric lighting that he did not enter. Yet as soon as the invention was actually before the world business competitors sprang up on every hand. There was more litigation over this than over any other of Edison’s inventions. “I fought for the lamp for fourteen years,” he said, “and when I finally won my rights there were but three years of the allotted seventeen left for my patent to live. Now it has become the property of anybody and everybody.”

Edison had always wanted a model laboratory, one that should be fitted with the most perfect instruments obtainable, and supplied with all the materials he could possibly require in any of his extraordinary experiments. In 1886 he bought a house in Llewellyn Park, New Jersey, and near the house ten acres of land, on which he built the laboratory of his dreams. Here he had a large force of skilled workmen constantly engaged in developing his ideas, and the expenses were paid by the many commercial companies in which he was interested, and which profited by the improvements he was continually making in their machinery.

Many volumes might be written to tell of the “Wizard’s” achievements. There has been no inventor who has covered such a field, and each step he takes opens new and fascinating vistas to his ever-inquiring eyes. Electricity is always his main study, and electricity he expects in time will revolutionize modern life by making heat, power, and light practically as cheap as air. But other subjects have concerned him almost as much. He ranges from new processes for making guns to the supplying of ready-made houses built of cement. Everything interests him, every object tempts him to try his hand at improving on it.

The phonograph is his achievement, and the practical development of the kinetoscope. He has built electric locomotives and run them, he has made many discoveries in regard to platinum. His better known patents include developments of the electric lamp, the telephone, storage-batteries, ore-milling machinery, typewriters, electric pens, vocal engines, addressing machines, cast-iron furniture, wire-drawing, methods of preserving fruit, moving-picture machines, compressed-air machines, and the manufacture of plate glass. He took out a patent covering wireless telegraphy in 1891, but other matters were then absorbing his attention, and he was quite willing to yield that field to the brilliant Italian, Marconi. He feels no jealousy for other inventors. He knows how vast the field is, and how many paths constantly beckon him.

It is doubtless true that the great inventors are born and not made, but many of them seem, nevertheless, to have drifted into the work that gave them fame, or to have hit by chance on their compelling idea. It was not so with Edison. He was beyond any doubt born an inventor. With him to see was to ask the question why, and to ask that question was to start his thoughts on the train that was to bring him to the answer.

XV

MARCONI AND THE WIRELESS TELEGRAPH

1874-

At first sight the wireless telegraph seems the most wonderful of all inventions and discoveries, the one that is least easy to understand, and that most nearly approaches that magic which is above all nature’s laws. Even if we do come to understand it it loses nothing of its wonder, and the last impression is very like the first. We can understand how an electric current travels through a wire, even if we cannot understand electricity, but how that current can travel through limitless space and yet reach its destination strains the imagination. Yet wireless telegraphy is not a matter of the imagination, but of exact, demonstrable science.

On December 12, 1901, a quiet, dark-skinned young man sat, about noontime, in a room of the old barracks building on Signal Hill, near St. John’s, Newfoundland. On the table in front of him was a mechanical apparatus, with an ordinary telephone receiver at its side. The window was partly open, and a wire led from the machine on the table through the window to a gigantic kite that a high wind kept flying fully 400 feet above the room. The young man picked up the receiver, and held it to his ear for a long time. His face showed no sign of excitement, though an assistant, standing near him, could barely keep still. Then, suddenly, came the sharp click of the “tapper” as it struck the “coherer.” That meant that something was coming. The young man listened a few minutes, and then handed the receiver to his assistant. “See if you can hear anything, Mr. Kemp,” said he. The other man took the receiver, and a moment later his ear caught the sound of three little clicks, faint, but distinct and unmistakable, the three dots of the letter S in the Morse Code. Those clicks had been sent from Poldhu, on the Cornish coast of England, and they had traveled through air across the Atlantic Ocean without any wire to guide them. That was one of the great moments of history. The young man at the table was Guglielmo Marconi, an Italian.

We know that it is no injustice to a great inventor to say that other men had imagined what he achieved, and had earlier tried to prove their theories. It takes nothing from the glory of that other great Italian, Columbus, to recall that other sailors had planned to cross the sea to the west of Europe and that some had tried it. So James Clerk-Maxwell had proved by mathematics the electro-magnetic theory of light in 1864, and Heinrich Hertz had demonstrated in 1888 by actual experiment that electric waves exist in the free ether, and Edison had for a time worked on the problem of a wireless telegraph. Marconi devised the last link that made the wonder possible, and caught the first click that came across the sea, and to him belong the palms. Judge Townsend, in deciding a suit in a United States court in 1905, declared, “It would seem, therefore, to be a sufficient answer to the attempts to belittle Marconi’s great invention that, with the whole scientific world awakened by the disclosures of Hertz in 1887 to the new and undeveloped possibilities of electric waves, nine years elapsed without a single practical or commercially successful result, and Marconi was the first to describe and the first to achieve the transmission of definite intelligible signals by means of these Hertzian waves.”

Marconi was born at Villa Griffone, near Bologna, in 1874, so that he was under thirty when he caught that first transatlantic message. He studied at Leghorn under Professor Rosa, and later at the University of Bologna with Professor Righi. He was always absorbed in science, and experimented, holiday after holiday, on his father’s estate. He was precocious to an extraordinary degree, for in 1895, when only twenty-one, he had produced a wireless transmitting apparatus that he patented in Italy. Within a year he had taken out patents in England and in other European countries, and had proposed a wireless telegraph system to the English Post-Office Department. That Department, through Sir William Henry Preece, Engineer-in-Chief of Telegraphs, took up the subject, and reported very favorably on the Marconi System. Marconi himself, at the House of Commons, telegraphed by wireless across the Thames, a distance of 250 yards. In June, 1897, he sent a message nine miles, in July twelve miles, and in 1898 he succeeded in sending one across the English Channel to France, thirty-two miles. In 1901 he covered a space of 3,000 miles.

Let us now see what it was that Marconi had actually done.

Wireless signals are in reality wave motions in the magnetic forces of the earth, or, in other words, disturbances of those forces. They are sent out through this magnetic field, and follow the earth’s curvature, in the same way that tidal waves follow the ocean’s surface. Everywhere about us there is a sea of what science calls the ether, and the ether is constantly in a state of turmoil, because it is the medium through which energy, radiating from the sun, is carried to the earth and other planets. This energy is transmitted through the free ether in waves, which are known as electromagnetic waves. It was this fact that Professor Hertz discovered, and the waves are sometimes called the Hertzian waves. Light is one variety of wave motion, and heat another. The ether must be distinguished from the air, for science means by it a medium which exists everywhere and is to be regarded as permeating all space and all matter. The ether exists in a vacuum, for, although all the air may have been withdrawn, an object placed in a vacuum can still be seen from outside, and hence the wave motions of light are traveling through a space devoid of air.

Professor Hertz proved in 1888 that a spark, or disruptive discharge of electricity, caused electro-magnetic waves to radiate away in all directions through the ether. The waves acted exactly like ripples that radiate from a stone when it strikes the water. These Hertzian waves were found to travel with the same velocity as light, and would circle the world eight times in a second. As soon as the existence of these waves was known many scientists began to consider whether they could not be used for telegraphy. But the problem was a very difficult one. The questions were how to transmit the energy to a distance, and how to make a receiver that should be sensitive enough to be affected by it.

Let us picture a body of still water with a twig floating upon its surface. If a stone is thrown into the water ripples radiate in all directions, these waves becoming weaker as the circles they form become larger, or in other words as they grow more distant from the point where the stone struck the water. When the waves reach the floating twig they will move it, and when they cease the twig will be motionless again. Should there be grasses or rocks protruding up from the water the motion given to the twig by the waves would be lessened, or distorted, or changed in many ways, depending on the intervening object. Whether the waves will actually impart motion to the twig will depend on the force by which these waves were started and upon the lightness of the twig, or its sensitiveness to the ripples as they radiate. If the water were disturbed by some other force than the stone the twig would be moved by that other force, and the observer could not tell from what direction the motion had come, or how it had been caused. Applying this to wireless telegraphy one may say that a device must be used that will send out waves of a certain length, and that the receiver must be constructed so that it will respond only to waves of the length sent by that transmitter.

There must therefore be accurate tuning of the two instruments. Let a weight be fastened at the end of a spiral spring and then be struck. The weight will oscillate at a uniform rate, or so many times a minute. If this be held so that it strikes the water the movement of the spring will create a certain number of waves a minute. If now a second weight, attached to a second spring, be hung down into the water, the waves caused by the first will reach the second, and if the springs be alike the movements or oscillations will correspond. But if the springs were not alike, or if, in other words, the two instruments were not in tune, the wave motions would not be received and copied accurately. Therefore in wireless telegraphy the instrument that is to impart the motion to the electro-magnetic waves that fill the ether must be tuned in accord with the instrument that is to receive the motion of those waves.

The sending of the wireless message requires a source of production of the electro-magnetic waves. This is obtained by what is known as capacity, or in other words, the power that is possessed by any metal surface to retain a charge of electricity, and by inductance, procured when a constantly changing current is sent through a coil of wire. This capacity and inductance must be adjusted to give exactly the same frequency of motion to the waves, or the same oscillations, if the receiver that is tuned to vibrate to those waves is to receive that message accurately. The receiving station must have the means to intercept the waves, and then transform them again into electrical oscillations that shall correspond to those sent out from the transmitting station.

As early as 1844 Samuel F. B. Morse had succeeded in telegraphing without wires under the Susquehanna River, and in 1854 James Bowman Lindsay, a Scotchman, had sent a message a distance of two miles through water without wires. Sir William Henry Preece, by using an induced current, had telegraphed several miles without a connecting wire. But the discoveries made in regard to the Hertzian waves placed the subject on a different footing, and the possibility of an actual usable wireless telegraph was now looked at from a new view-point.

Professor Hertz had used a simple form of apparatus to obtain his free ether waves. A loop of wire, with the ends almost touching each other, had been his receiver, or detector. When he set his generator, or instrument to create the oscillations, in operation, and held the detector near it, he could see very minute electric sparks passing between the ends of the loop of wire. This proved the existence of the electro-magnetic waves.

In 1890 Professor Eduard Branly found that loose metallic filings became good conductors of electricity when there were electric oscillations at hand. He demonstrated this by placing the filings between metal plugs in a glass tube, and connecting this in circuit with a battery and electric indicator. Professor Oliver Lodge named this device of Branly’s a “coherer,” and when he found that it was more sensitive than the Hertz detector he combined it with the Hertz oscillator. This was in 1894, and the combination of oscillator and coherer actually formed the first real wireless set.

Wireless stations on shore are marked by very tall masts, which support a single wire, or a set of wires, which are known as the _antenna_. The antenna has electrical capacity, and when it is connected with the other apparatus needful to produce the oscillations it disturbs the earth’s magnetic field. For temporary service, as in the case of military operations, the antenna is frequently attached to captive balloons or kites, and so suspended high in air. On ships the antenna is fastened to the masts. The step that led to this addition was taken by Count Popoff in 1895, when he attached a vertical wire to one side of the coherer of the receiver of Professor Lodge, and connected the other side with the ground. He used this to learn the approach of thunder-storms.

With a knowledge of electro-magnetic waves, with a high-power oscillator, and a sensitive coherer, it remained for Marconi to connect an antenna to the transmitter, and thus secure a wide and practicable working field for the sending and receiving of his messages. This he did in 1896, and it was this addition that made the wireless telegraph of real use to men. Improvements in the transmitter and receiver have constantly increased the power of the invention, and have gradually allowed him to employ it over greater and greater distances.

With Marconi’s successful demonstrations of wireless in England its use at once began. The Trinity House installed a station at the East Goodwin Lighthouse, which communicated with shore and proved of the greatest value in preventing shipwrecks. The Marconi Wireless Telegraph Company was organized in 1897, and made agreements to erect coast stations for the Italian, Canadian, and Newfoundland governments, and for Lloyd’s. The great shipping lines established wireless stations on their vessels, and the antenna were soon to be seen on points of vantage along every coast. On December 12, 1901, Marconi in Newfoundland caught the message sent from Cornwall; on January 19, 1903, President Roosevelt sent the first “official” wireless message across the Atlantic to Edward VII, and in October, 1905, a message was sent from England across the mountains, valleys and cities of Europe to the battle-ship _Renown_, stationed at the entrance to the Suez Canal.