A story of wireless telegraphy

Front matter

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Contents

Introduction — Fairy-tales of Science — ^Early Dreams of Wireless Telegraphy — ^The Conduction Method — ^Induction — The Magnetic Field — Electro-magnetic Waves — ^Electricity and Light — Clerk-Maxwell's Thecry — ^Researches of Hertz — First Hint of Etheric Telegraphy — ^Radiophony — Light Telegraphy 9

CHAPTER I Steinhail's Anticipation of Wireless Telegraphy

ductivity of the Earth — Its Use in Place of a Second Wire — ^Telegraphing Through the Earth — Anticipation of the Radiophone — Morse's Experiments in Wireless Telegraphy — His Results 18

Chapter II

Wilkins's Proposed Method of Wireless Communication with France — ^Bering's Experiments with Conduction through Water — Lindsay — His Electrical Researches — Proposal to Telegraph Across the Atlantic — His Method — ^Exoeriments Across the Tay and Elsewhere 26

Chapter III

Highton and his Suggestions — Other Experimenters in Wireless Telegraphy — A Proposal to Communicate with Besieged Paris by Telegraphy through the Water — ^Its Necessity Obviated by the Armistice — ^Wireless Telegraphy in India — An American Dentist's Conception and Experiments • . 40 id CONTENTS.

Chapter IV Page

Effect of Improvements in Cables — Invention of the Telephone — ^Researches of Professor Trowbridge with — His Experiments with Wireless Telegraphy — Professor Graham Bell's Investigations — Dolbear's Working with Etheric Waves — ^his Anticipation of Marconi . 48

Chapter V

Telegraphic Communication with Trains — ^A. C. Brown's Method — Willoughby Smith and Phelps's Suggestions —Successful Application of the Principle by Edison and Gilliland — Edison's Method Applied to Ships — ^Sir William Preece's Researches — His Experiments on the Solent — Across the Severn — At Porthcawl — On the Bristol Channel — Loch Ness — ^The Island of Mull — His Theory of the Part Played by the Earth in Electromagnetic Operations • 65

Chapter VI

Willoughby Smith's Experiments in Conduction through Water and Earth — Smith and Granville's Experiments at the Needles Lighthouse — Application of their Method to the Fastnet Lighthouse — The Investigations of C. A. Stevenson in Electro-magnetic Conduction and Induction — Preece and Stevenson's Experiments Awaken Interest on the Continent — Professor Rathenau's Investigations — Evershed's Experiments at the Goodwin Lightship — Preece's Experiments at the Skerries and Rathlin Island — His Views as to Earth Conduction, etc 85

Chapter VII

Hertz's Great Discovery of Electromagnetic Waves — ^His Apparatus — Clerk-Maxwell's Hypothesis — Sir Oliver Lodge on Maxwell and Hertz — ^The Identity of Electricity with Light — Professor Hughes and his Researches — ^Sir William Crookes's Prediction — Hughes's Account of his Experiments — His Wireless Telegraphy ^-Discouragement by Scientific Experts 10 1

CONTENTS. vii

Chapter VIII Page

The Imperfect Means at Hertz's Command — ^The Coherer and Its History — Guitard — ^Varley — Onesti — Professor Branly — His Radioconductor — Sir Oliver Lodge and the Coherer — His Experiment at Oxford in 1894 — Rutherford — Dr. Muiiiiead — Captain Jackson — Professor Bose — Professor Righi — Lodge's New Coherer —Popoflf's Experiments 118

Chapter IX

Gradual Evolution of Wireless Telegraphy — ^Marconi's Beginnings — Studies at Bologna — Arrival in England and Introduction to Sir William Preece — His Indebtedness to Righi and Others — His Originality in Seeing Farther than Others — ^Description of his System — ^His Oscillator — ^The Coherer — ^Tne Action of the Whole Apparatus 130

Chapter X

Marconi's First Experiments in England— Trials on the Bristol Channel— Also between the Needles and Bournemouth — Experiments at Spezia — Valuable Results Obtained — Professor Slaby's Investigations at Potsdam and Elsewhere — Further Experiments by Marconi — Wireless Telegraphy on Board the Royal Yacht — ^Aerial Communications between England and France — British and French Associations for the Advancement of Science — Wireless Telegraphy at the Naval Maneuvers — Experiments of the Brothers Lacarme — Communications with Balloons — ^Trials by the United States Navy Board, etc 147

Chapter XI

The American Navy Board and "Interference"— Wireless Telegraphy Experiments at Calvi, Corsica — ^Syntony Imperfectly Attained — Sir Oliver Lodge and Syntony — ^Signals Received at St. John's, Newfoundland, from Cornwall — The Influence of Sunlight upon Sending Wires — Experiments on the Carlo Alberta — The Apparatus on Board and at Poldhu — Report on viii CONTENTS.

PAGE.

the Results — Marconi's Detector — Criticisms on the Report — Tapping the Messages — Syntony again — Achievement of Transatlantic Telegraphy without Wires 164

Chapter XII

The System of Professor Braun — ^The Orling-Armstrong Method — Further Particulars of the Lodge-Muirhead System — ^Two American Wireless Methods — ^That of Dr. Lee de Forest — Professor Fessenden*s Discoveries — ^His System — ^The Future of Wireless Telegraphy • 180

Introduction

Fairy Tales of Science — Early Dreams of Wireless Telegraphy — The Conduction Method — Induction — The Magnetic Field — Electromagnetic Waves — Electricity and Li^t — Clerk-Maxwell's Theory — Researches of Hertz— First Hint of Etheric Telegraphy—Radiophony — Light Telegraphy.

The past century witnessed the discovery and development of many (as they may be called) fairy tales of science; but none of them — ^wonderful as they on their first inception seemed — strike the imagination with such a sense of the wonder-worker at play as the marvels of Wireless Telegraphy. Electric telegraphy itself was in the days of its early trials and successes regarded as something almost necromantic; and when pioneers in science began to speculate about and to forecast its application to ocean telegraphy they were regarded somewhat as moonstruck dreamers and phantasiasts of the castlein-the-air variety. But ocean telegraphy came, and then, before the century, of whose mid decades it was a triumph, reached its end, it was followed by the realization of another dream, and in the wonder-book of the nineteenth century was written another fairy tale of man*s triumph over matter and over space in the achievement of electric telegraphy without wires.

As we shall see in the following pages, the anticipation, the forecast of such a triumph, was in men*s minds from the very earliest days of telegraphy, and from that time to the present keen intellects and indomitable wills — one after another — ^never ceased to be turned to the solution of the problem. First they sought an answer in one direction, then in another. Ever there was a reply sufficiently alluring to keep the ball rolling— to keep the ranks of the investigators full ; and the achievements of one generation of workers after another served as the steppingstones over which their successors moved to more assured successes, until finally the goal was won, if we can consider anything as final when there is so much still to win from the unknown.

There were in the earlier half of the last century two methods familiar to men of science by which it was hoped that one day it would be possible to convey messages from place to place without the use of wires. One of these methods was that known as Conduction, by which the conductive properties of the earth and water are

CONDUCTION AND INDUCTION. II

turned to account for conveying the electric force; the other is that known as Induction, by which is signified the property an electric impulse has, so to speak, of transferring itself from one place to another.

But toward the end of the century, a third principle was discovered, which suddenly and most unexpectedly took precedence of the other two, and with almost startling rapidity was turned to account as a means of electrically communicating between distant places without connection by wires. This third method is that known as the radiation of electromagnetic waves through space.

It will be convenient here, by way of preliminary statement, to give a brief explanation of these different principles of electrical action. To take Conduction first — ^this is the property certain bodies possess of allowing heat, sound, and electricity to pass through them. Thus the felled trunk of a tree is a good conductor of sound. Metal is a conductor of heat, as may be proved by putting one end of a metal rod in the fire and taking hold of the other end. Electricity finds its way through certain substances in the same manner, and in proportion to the ease of such passage is it a good or an indifferent conductor. The fact that copper wire was early found to be so good a conductor caused it to be selected as the best material for ordinary telegraphic purposes. It will be seen, before we have proceeded very far in our account of wireless telegraphy, that water and the solid ground also are conductors, and it was the discovery of this fact which turned the attention of investigators to the earth as a means of telegraphing without the connecting link of wires.

What Induction is may best be explained by a simple diagram (Fig. i). Fig. i represents two

circuits, in the first of which (A) represents a galvanic battery and (B) an interrupter, by means of which the current of electricity can be closed or broken at will; c^sX/) while in the other,

FiG. I. which remains

always closed, a galvanometer (C) is included. Every time that the inducing wire, that is the one containing the battery, is closed, a short, constant current is set up in the other, or induced, wire or circuit, and this secondary current has much the same duration as that in the inductive current. If the latter be broken there arises in the induced circuit, a current whose direction is opposed to that in the primary circuit, and this phenomenon is repeated

ELECTRO MAGNETIC WAVES. 1 3

every time the current in the inducing wire is interrupted. The two wires may be a few feet or several miles apart, but whether the one or the other, induction takes place all the same. Another circumstance connected with this singular appearance is that directly the current in the primary wire begins to flow, as we say, what is called a magnetic field is set up all round it and, so far as we understand, is the cause of the induction. But the whole phenomenon is still involved in a good deal of mystery, and will require the genius of another Faraday, whose peculiar glory it is to have first discovered the principle, thoroughly to lay bare its secret.

The third method of telegraphing without wires, that based on the phenomenon known as electrostatic waves, is the most surprising of all, and up to the present time has produced the most wonderful results, although it is quite possible that they may be outdone in the future by other forms of electrical action. The existence of these electromagnetic waves has only been known since 1888, and the story of their discovery is one of the romances of science. We shall come to that epoch-making event in due course : all that it is necessary to say here is that by means of disruptive electrical discharges electromagnetic oscillations are set up in the ether with which all space is filled, and that upon these oscillations, or waves, by instruments properly adapted to that end, signals may be transmitted and received, as in ordinary telegraphy.

These waves move with a velocity equaling that of light, with which they are held to have an intimate connection, and vary in size according to the strength of the impulses which starts

_% them on their course,

wt^? ^^2?"^^^ some being, as it were, ^ ^^^^^'^ ^^^^^^ mere ripples while

others stretch to hundreds and even thousands of miles in length. They are of course invisible to the unaided eye, though the eye of the camera has seen and transfixed them (Fig. 2).

The first hint of the existence of these electromagnetic waves was given by Professor J. Qerk- Maxwell of Cambridge, who, struck by the value of a certain coefiicient, very important in the study of electrical phenomena, and by its agreement with the figure which represents the velocity of the propagation of light, was one day strongly impressed with the extreme likelihood that light and electricity were essentially the same. Building upon this apparent identity, he worked out an hypothesis in regard to the constitution of the medium in which these phenomena exist, and in due course, as a French writer puts it, "gave to the world the edifice of his thought."

ELECTRO MAGNETIC WAVES. 1 5

Part of that edifice consisted in the theory that electricity, like light, traverses space through the medium of the ether, and that if, by a disruptive discharge, a magnetic flux is created in any place it spreads outward or extends itself by an undulatory motion similar to what we see in a body of water when a stone is dropped into it. Twenty-five years later a German professor named Heinrich Hertz, deeply imbued with the teachings of Maxwell, and stimulated by a chance observation that has already become classic, conceived the idea of establishing his theories by practical experiment. To this end he devised an apparatus peculiarly adapted to his purpose, and with it not only succeeded in making a brilliant demonstration of the truth of Maxwell's conception, but, going still further in his researches, ended by giving to the world a means of communicating through space on the ether-piercing rays of electricity.

As already said, this magnificent discovery was given to the world in 1888. It was barely made public ere a German engineer named Huber questioned Hertz as to the possibility of making use of the electromagnetic waves as a means of telegraphing without wires. Hertz threw cold water on the idea. He had not grasped the full significance of his own discovery; and indeed other discoveries and inventions were necessary for the practical realization of the idea thus thrown out. But there were not wanting minds who perceived something of the scope and grandeur of the role this Maxwell-Hertz discovery was destined to play in the near future, and these, as we shall see, were soon at work moving, unconsciously for the most part, toward a certain end.

I have mentioned three methods of turning electrical energy to account for the production of wireless telegraphy. But there is still another which ought not to be passed over in such an account as this, the more especially as it is one that may yet play an important part in intercommunication between place and place. I refer to telegraphy by means of light rays. Radiophony, the discovery whereof is usually attributed to Professor Graham Bell, but the honor of which belongs as much to Mr. A. C. Brown, is based upon the phenomena, made known in 1878, that selenium possesses, under certain conditions, the property that when placed under a ray of light it opposes to an electrical current a less resistance than when it is in the dark. In other words, it is a better conductor in the light than in the dark.

The discovery appears to have been first made by one of Mr. Willoughby Smith's assistants ; although Siemens lighted on the same fact almost contemporaneously. Bell, however, in collaboration with Sumner Tainter, continued

RADIOPHONY. I ^

and extended his researches with a view to ascertaining whether other substances possessed the like quaHties, with the result that he found, among others, that gold, silver, iron, ivory, gutta-percha, paper, wood, mica, glass, etc., were similarly sensitive to light, although in a less degree than selenium.

On the basis of this observation Bell proceeded to devise an apparatus whereby a ray of light could be thrown upon a selenium cell. The cell was connected with a battery and a telephone in a circuit in such a way that every change in the resistance of the selenium, and the therewith associated change in the strength of the current in the telephone, could be at once detected. By shutting off the light rays at short regular intervals, signals could thus be transmitted, and these were distinctly repeated in the telephone. This delicate instrument, first made public in 1880, was originally designated the photophone, a name which was subsequently changed to radiophone. The same idea was further developed some years later; but of this invention we shall have something to say later in connection with Hertz and his investigations, and so need make no further reference to it at this point.

Chapter I

Steinheil's anticipation of Wireless Telegraphy — Conductivity of the Earth — Its use in place of a second wire —Telegraphing through the Earth — ^Anticipation of the Radiophone — Morse's experiments in Wireless Telegraphy — ^His results.

The story of Wireless Telegraphy presents us with a number of names of men who may be said to have predicted the future triumph of such a form of communicating between place and place, if we may accept what appear to have been mere wide-awake dreams as prediction. Setting these aside, however, as not germane to our subject, we come, in the scientific records of 1838, to the name of one who may with truth be said to have laid the foundation of telegraphy without wires. This was Prof. C. A. Steinheil of Munich, who in the year named gave to the world a very clear and intelligent anticipation of this form of electric communication. Being associated with Gauss — who, along with Weber, had been the first to demonstrate the practicability of electric telegraphy — during the time that he was constructing his famous system of telegraphy in Bavaria, that distinguished scientist suggested to him the possibility of utilizing the two lines 18

STEINHEIL'S EXPERIMENTS. 1 9

of a railway as telegraphic conductors. Steinheil was struck with the suggestion, and put it to the test of experiment on the line between Nuremberg and Fiirth. The attempt, however, proved a failure because of the impossibility of so isolating the rails as to prevent the passage of the electric current from one rail to another through the ground.

But if Steinheirs researches turned out unsuccessful in this particular respect, they nevertheless led to a most important discovery. For he found that the conductivity of the earth was so great that it led him to believe that it might be turned to advantage for the return current in place of the second wire previously used. The experiments instituted to test the truth of this inference proved entirely successful, and he was thus enabled, by the introduction of this earth circuit, to make one of the most important contributions toward successful telegraphy.

In the account Steinheil gives of his discovery, and the practical use he made of it, he says: " It appeared of especial interest to inquire into the laws of dispersion, whereby the ground, whose mass is limited, is acted upon by the passage of the galvanic current. The galvanic current cannot confine itself merely to the portions of earth situated between the two ends of the wire, but must spread out indefinitely on every hand, and it only depends, therefore, on the relation in which this law as to the excitation of the ground stands to the distance of the exciting terminations of the wire, whether any metallic connection at all is necessary for carrying on telegraphic communication.

" I can here only briefly state that I have discovered a means of putting the law of this phenomenon to the test, of experiment, with the result that it is seen that the excitation quickly declines as the distance from the exciting conductor is increased.

" Appliances can indeed be constructed (Steinheil goes on to say), in which the indicator, having no metallic connection with the multiplier, generates currents in that multiplier, through the excitation of the ground alone, sufficient to cause visible deflections of the bar. This is a hitherto unobserved fact, and may be classed among the most extraordinary phenomena that science has revealed to us. It only holds good, however, for small distances, and we must leave it to the future to decide whether it will ever be possible to telegraph to great distances entirely without metallic connection. For distances up to fifty feet, I have proved the possibility of such electric communication by experiment. For greater distances we can only conceive it possible by augmenting the power of the galvanic induction, or by appropriate multipliers constructed for the purpose, or, finally, by increas-

STEINHEIL»S EXPERIMENTS. 21

ing the surface of contact presented by the ends of the multipliers. In any case the phenomenon is worthy of our best attention, and it may not perhaps be without influence upon the theoretic view we may form in regard to the nature of galvanism itself."

Thus was the possibility of wireless telegraphy first scientifically demonstrated. Steinheil's experiments, however, did not lead him in the end to any very sanguine anticipations in regard to the practical value of such telegraphy, and in referring to the subject in his Application of Electro-Magnetism,* he makes the following observation : " The spreading of the galvanic effect is proportional, not to the distance of the point of excitation, but to the square of this distance ; so that, at the distance of fifty feet, only exceedingly small effects can be produced by the most powerful electrical effect at the point of excitation. Had we the means which could stand in the same relation to electricity that the eye stands to light, nothing would prevent our telegraphing through the earth without conducting wires ; but it is not probable that we shall ever attain that end."

While Professor Steinheil's mind was thus intent upon the subject of wireless telegraphy he struck out another idea in connection therewith, and thereby curiously anticipated Graham Bell's radiophone. His proposed method was to direct

* Die Anwendung des Electromagnetismus.

22 THE STORY OF WIRELESS TELEGRArHY.

radiant heat upon a thermoelectric pile by means of condensing mirrors, thus calling ^ galvanic current into action, which in its turn could be employed to bring about declinations of a magnetic needle. Though Steinheil foresaw considerable difficulties in the working out of this principle, he held that they were not insuperable. Others since his time have given much time and thought to the subject; but it would take us too far away from the main line of investigation regarding wireless telegraphy to go into the matter here.

Following Steinheil, little beyond some scientific dreaming was done until Professor S. F. B. Morse, Superintendent of Telegraphs to the Government of the United States, inventor of the telegraphic alphabet known by his name, began to experiment with a view to seeing what could be done by way of dispensing with artificial conductors. His first experiments were made in the autumn of 1842, when, at the request of the American Institute, he undertook to give to the public of New York a demonstration of the practicability of his telegraph, and for that purpose laid wires between Governor's Island and Castle Garden, a distance of a mile. To his intense mortification, however, soon after he had begun operations, his purpose was frustrated by the accidental destruction of a part of his conductors by a vessel which drew them up with its

MORSE'S EXPERIMENTS. IJ

anchor and cut them off. The accident, however, proved to be a fortunate circumstance, as it put into Morse's head the idea of arranging his wires along the banks of the stream, and so trying if the water itself would conduct the electricity across.

His first experiments according to this new method were made in December, 1842, across a canal at Washington, and proved eminently successful. These experiments were continued by Professor Gale on Morse's behalf, and in writing to the Secretary of the United States Treasury on the subject of his experiments, on December 23, 1844, Morse says : " The simple fact was then ascertained that electricity could be made to cross a river without other conductors than the water itself."

Morse repeated his experiments on a larger scale in the autumn of 1844, his aim then being, as he explains, to ascertain the law ruling the passage of electricity across a body of water. The nature of his experiment will be understood from the annexed diagram (Fig. 3).

A, B, C, D are the banks of the river; P, R is the battery; G is a galvanometer; W, W are the wires along the banks, connected with copper plates, /, g, h, i, which are placed in the water. According to Morse, the electricity, generated by the battery, passes from the positive pole P to the plate h, across the river through the water to plate i, and thence around the coil of the galvanometer to plate /, across the river again to plate g, and thence to the other pole of the battery R, to complete the circuit.

These experiments were made with different lengths of wire laid along the banks of the canal, and with batteries, the number of elements composing which were of different strengths. In the

Fig. 3.

result it was found that the quantity of electricity which passed from one bank of the stream to the other stood in direct relationship to the size of the plates sunk in the water, as well as to the distance of the plates on the same side of the river from each other. From these and other experiments it was deduced that this distance should be three times greater than that from shore to shore. A greater distance than that did not give any increase of power.

Similar experiments were carried out by Messrs. Vail and Rogers, two of Professor where the distance separating the two circuits Morse's assistants, across the Susquehanna River,

VAIL AND ROGERS 2$

was nearly a mile, and with complete success. It is curious to note that, in his communication to the Secretary of the Treasury, Morse remarks that " experience alone can determine whether lofty spars, on which wires may be suspended, erected in the rivers, may not be deemed the most practical."

A full account of these experiments is given in Alfred Vail's American Electromagnetic Telegraph, published in 1845, ^^^ reprinted in the Electrical World, June 29, 1895.

Chapter II

Wilkins' proposed method of wireless communication with France — Bering's experiments with conduction through water — Lindsay — His electrical researches — Proposal to telegraph across the Atlantic — His method — Experiments across the Tay and elsewhere.

The next worker in the field of wireless telegraphy of whom we have any knowledge is Mr. J. W. Wilkins, whose experiments were begun in 1845. Wilkins was associated for many years with Messrs. Cooke and Wheatstone, the pioneers of electric telegraphy in Great Britain ; and in a letter appearing in the Mining Journal, March 28, 1849, he clearly sets forth a method whereby, as he conceived, telegraphic communication might be established between England and France, which the submarine cable had not at that time joined. As this letter, from the suggestions it contains, is of great importance in the history of wireless telegraphy, it will be well to give almost entire the writer's description of the method by which he proposed to carry out his " theory upon which a telegraphic communication may be made between England and France without wires."

" I take for certain," he proceeds — " as experi- 26

WILKINS' SUGGESTION. ^^

ments I have made have shown me — ^that when the positive and negative poles of a battery are dipped into or connected with any conducting medium, the electricity around the positive pole is positive, being diffused in radial lines, and the part around the negative pole is negative in radial lines converging toward it, supplying the electricity requisite for the decomposition of the substances composing the battery. This understood, it is evident that when a positive radial line sets out from the junction of the battery with the earth it makes its way to, or is attracted by the nearest negative portion of earth, at last meeting the negative pole of the battery, restoring the equilibrium. From this it appears that the first portion of electricity will pass in a straight line between the two poles, being the shortest between them, and the rays will then form curves between the poles until, by reason of increasing distance, they are no longer influenced by one another, without a better medium of conduction be interposed in their circuit.

" It is natural to suppose that all parts of the earth are not of one uniform density ; if so, then some parts are positive, and others negative. Then from this it is easy to see that some of the electricity flowing from the positive pole is the means of restoring equilibrium to negative portions of the earth — ^not necessarily rendered so

•

by the negative pole of the battery; and also positive portions, for the same reason, rendered neutral or negative.

" These rays of electricity may be collected in a certain quantity between the point whence they start, and where they are rendered neutral, and by the interposition of a metallic medium that shall offer less resistance than the water or earth — obviously the nearer the battery the greater the chance of collecting them. I do not anticipate the distance of twenty miles is at all too much (with the means we can use to compensate it) to collect a sufficient quantity of current to be useful for telegraphic purposes. Still, the quantity would be small, and with the present telegraphic instruments would not be detected at all. The current in the wire (of the instrument used) must be detected — not by its amount, but that it exists in any quantity, however small. If, then, electricity can be collected in France, simultaneously with a discharge from a battery in England, all that is required is, to find out what to do with it, so that it shall indicate its presence.