A CHAPTER IN THE HISTORY OF SCIENCE: WIRELESS TELEGRAPHY
§ 1
I have endeavoured in this book to set forth impartially the ideas
dominant at this moment in the domain of physics, and to make known
the facts essential to them. I have had to quote the authors of the
principal discoveries in order to be able to class and, in some sort,
to name these discoveries; but I in no way claim to write even a
summary history of the physics of the day.
I am not unaware that, as has often been said, contemporary history is
the most difficult of all histories to write. A certain step backwards
seems necessary in order to enable us to appreciate correctly the
relative importance of events, and details conceal the full view from
eyes which are too close to them, as the trees prevent us from seeing
the forest. The event which produces a great sensation has often only
insignificant consequences; while another, which seemed at the outset
of the least importance and little worthy of note, has in the long run
a widespread and deep influence.
If, however, we deal with the history of a positive discovery,
contemporaries who possess immediate information, and are in a
position to collect authentic evidence at first hand, will make, by
bringing to it their sincere testimony, a work of erudition which may
be very useful, but which we may be tempted to look upon as very easy
of execution. Yet such a labour, even when limited to the study of a
very minute question or of a recent invention, is far from being
accomplished without the historian stumbling over serious obstacles.
An invention is never, in reality, to be attributed to a single
author. It is the result of the work of many collaborators who
sometimes have no acquaintance with one another, and is often the
fruit of obscure labours. Public opinion, however, wilfully simple in
face of a sensational discovery, insists that the historian should
also act as judge; and it is the historian's task to disentangle the
truth in the midst of the contest, and to declare infallibly to whom
the acknowledgments of mankind should be paid. He must, in his
capacity as skilled expert, expose piracies, detect the most carefully
hidden plagiarisms, and discuss the delicate question of priority;
while he must not be deluded by those who do not fear to announce, in
bold accents, that they have solved problems of which they find the
solution imminent, and who, the day after its final elucidation by
third parties, proclaim themselves its true discoverers. He must rise
above a partiality which deems itself excusable because it proceeds
from national pride; and, finally, he must seek with patience for what
has gone before. While thus retreating step by step he runs the risk
of losing himself in the night of time.
An example of yesterday seems to show the difficulties of such a task.
Among recent discoveries the invention of wireless telegraphy is one
of those which have rapidly become popular, and looks, as it were, an
exact subject clearly marked out. Many attempts have already been made
to write its history. Mr J.J. Fahie published in England as early as
1899 an interesting work entitled the _History of Wireless
Telegraphy_; and about the same time M. Broca published in France a
very exhaustive work named _La Telegraphie sans fil_. Among the
reports presented to the Congrès international de physique (Paris,
1900), Signor Righi, an illustrious Italian scholar, whose personal
efforts have largely contributed to the invention of the present
system of telegraphy, devoted a chapter, short, but sufficiently
complete, of his masterly report on Hertzian waves, to the history of
wireless telegraphy. The same author, in association with Herr
Bernhard Dessau, has likewise written a more important work, _Die
Telegraphie ohne Draht_; and _La Telegraphie sans fil et les ondes
Électriques_ of MM. J. Boulanger and G. Ferrié may also be consulted
with advantage, as may _La Telegraphie sans fil_ of Signor Dominico
Mazotto. Quite recently Mr A. Story has given us in a little volume
called _The Story of Wireless Telegraphy_, a condensed but very
precise recapitulation of all the attempts which have been made to
establish telegraphic communication without the intermediary of a
conducting wire. Mr Story has examined many documents, has sometimes
brought curious facts to light, and has studied even the most recently
adopted apparatus.
It may be interesting, by utilising the information supplied by these
authors and supplementing them when necessary by others, to trace the
sources of this modern discovery, to follow its developments, and thus
to prove once more how much a matter, most simple in appearance,
demands extensive and complex researches on the part of an author
desirous of writing a definitive work.
§ 2
The first, and not the least difficulty, is to clearly define the
subject. The words "wireless telegraphy," which at first seem to
correspond to a simple and perfectly clear idea, may in reality apply
to two series of questions, very different in the mind of a physicist,
between which it is important to distinguish. The transmission of
signals demands three organs which all appear indispensable: the
transmitter, the receiver, and, between the two, an intermediary
establishing the communication. This intermediary is generally the
most costly part of the installation and the most difficult to set up,
while it is here that the sensible losses of energy at the expense of
good output occur. And yet our present ideas cause us to consider this
intermediary as more than ever impossible to suppress; since, if we
are definitely quit of the conception of action at a distance, it
becomes inconceivable to us that energy can be communicated from one
point to another without being carried by some intervening medium.
But, practically, the line will be suppressed if, instead of
constructing it artificially, we use to replace it one of the natural
media which separate two points on the earth. These natural media are
divided into two very distinct categories, and from this
classification arise two series of questions to be examined.
Between the two points in question there are, first, the material
media such as the air, the earth, and the water. For a long time we
have used for transmissions to a distance the elastic properties of
the air, and more recently the electric conductivity of the soil and
of water, particularly that of the sea.
Modern physics leads us on the other hand, as we have seen, to
consider that there exists throughout the whole of the universe
another and more subtle medium which penetrates everywhere, is endowed
with elasticity _in vacuo_, and retains its elasticity when it
penetrates into a great number of bodies, such as the air. This medium
is the luminous ether which possesses, as we cannot doubt, the
property of being able to transmit energy, since it itself brings to
us by far the larger part of the energy which we possess on earth and
which we find in the movements of the atmosphere, or of waterfalls,
and in the coal mines proceeding from the decomposition of carbon
compounds under the influence of the solar energy. For a long time
also before the existence of the ether was known, the duty of
transmitting signals was entrusted to it. Thus through the ages a
double evolution is unfolded which has to be followed by the historian
who is ambitious of completeness.
§ 3
If such an historian were to examine from the beginning the first
order of questions, he might, no doubt, speak only briefly of the
attempts earlier than electric telegraphy. Without seeking to be
paradoxical, he certainly ought to mention the invention of the
speaking-trumpet and other similar inventions which for a long time
have enabled mankind, by the ingenious use of the elastic properties
of the natural media, to communicate at greater distances than they
could have attained without the aid of art. After this in some sort
prehistoric period had been rapidly run through, he would have to
follow very closely the development of electric telegraphy. Almost
from the outset, and shortly after Ampère had made public the idea of
constructing a telegraph, and the day after Gauss and Weber set up
between their houses in Göttingen the first line really used, it was
thought that the conducting properties of the earth and water might be
made of service.
The history of these trials is very long, and is closely mixed up with
the history of ordinary telegraphy; long chapters for some time past
have been devoted to it in telegraphic treatises. It was in 1838,
however, that Professor C.A. Steinheil of Munich expressed, for the
first time, the clear idea of suppressing the return wire and
replacing it by a connection of the line wire to the earth. He thus at
one step covered half the way, the easiest, it is true, which was to
lead to the final goal, since he saved the use of one-half of the line
of wire. Steinheil, advised, perhaps, by Gauss, had, moreover, a very
exact conception of the part taken by the earth considered as a
conducting body. He seems to have well understood that, in certain
conditions, the resistance of such a conductor, though supposed to be
unlimited, might be independent of the distance apart of the
electrodes which carry the current and allow it to go forth. He
likewise thought of using the railway lines to transmit telegraphic
signals.
Several scholars who from the first had turned their minds to
telegraphy, had analogous ideas. It was thus that S.F.B. Morse,
superintendent of the Government telegraphs in the United States,
whose name is universally known in connection with the very simple
apparatus invented by him, made experiments in the autumn of 1842
before a special commission in New York and a numerous public
audience, to show how surely and how easily his apparatus worked. In
the very midst of his experiments a very happy idea occurred to him of
replacing by the water of a canal, the length of about a mile of wire
which had been suddenly and accidentally destroyed. This accident,
which for a moment compromised the legitimate success the celebrated
engineer expected, thus suggested to him a fruitful idea which he did
not forget. He subsequently repeated attempts to thus utilise the
earth and water, and obtained some very remarkable results.
It is not possible to quote here all the researches undertaken with
the same purpose, to which are more particularly attached the names of
S.W. Wilkins, Wheatstone, and H. Highton, in England; of Bonetti in
Italy, Gintl in Austria, Bouchot and Donat in France; but there are
some which cannot be recalled without emotion.
On the 17th December 1870, a physicist who has left in the University
of Paris a lasting name, M. d'Almeida, at that time Professor at the
Lycée Henri IV. and later Inspector-General of Public Instruction,
quitted Paris, then besieged, in a balloon, and descended in the midst
of the German lines. He succeeded, after a perilous journey, in
gaining Havre by way of Bordeaux and Lyons; and after procuring the
necessary apparatus in England, he descended the Seine as far as
Poissy, which he reached on the 14th January 1871. After his
departure, two other scholars, MM. Desains and Bourbouze, relieving
each other day and night, waited at Paris, in a wherry on the Seine,
ready to receive the signal which they awaited with patriotic anxiety.
It was a question of working a process devised by the last-named pair,
in which the water of the river acted the part of the line wire. On
the 23rd January the communication at last seemed to be established,
but unfortunately, first the armistice and then the surrender of Paris
rendered useless the valuable result of this noble effort.
Special mention is also due to the experiments made by the Indian
Telegraph Office, under the direction of Mr Johnson and afterwards of
Mr W.F. Melhuish. They led, indeed, in 1889 to such satisfactory
results that a telegraph service, in which the line wire was replaced
by the earth, worked practically and regularly. Other attempts were
also made during the latter half of the nineteenth century to transmit
signals through the sea. They preceded the epoch when, thanks to
numerous physicists, among whom Lord Kelvin undoubtedly occupies a
preponderating position, we succeeded in sinking the first cable; but
they were not abandoned, even after that date, for they gave hopes of
a much more economical solution of the problem. Among the most
interesting are remembered those that S.W. Wilkins carried on for a
long time between France and England. Like Cooke and Wheatstone, he
thought of using as a receiver an apparatus which in some features
resembles the present receiver of the submarine telegraph. Later,
George E. Dering, then James Bowman and Lindsay, made on the same
lines trials which are worthy of being remembered.
But it is only in our own days that Sir William H. Preece at last
obtained for the first time really practical results. Sir William
himself effected and caused to be executed by his associates--he is
chief consulting engineer to the General Post Office in England--
researches conducted with much method and based on precise theoretical
considerations. He thus succeeded in establishing very easy, clear,
and regular communications between various places; for example, across
the Bristol Channel. The long series of operations accomplished by so
many seekers, with the object of substituting a material and natural
medium for the artificial lines of metal, thus met with an undoubted
success which was soon to be eclipsed by the widely-known experiments
directed into a different line by Marconi.
It is right to add that Sir William Preece had himself utilised
induction phenomena in his experiments, and had begun researches with
the aid of electric waves. Much is due to him for the welcome he gave
to Marconi; it is certainly thanks to the advice and the material
support he found in Sir William that the young scholar succeeded in
effecting his sensational experiments.
§ 4
The starting-point of the experiments based on the properties of the
luminous ether, and having for their object the transmission of
signals, is very remote; and it would be a very laborious task to hunt
up all the work accomplished in that direction, even if we were to
confine ourselves to those in which electrical reactions play a part.
An electric reaction, an electrostatic influence, or an
electromagnetic phenomenon, is transmitted at a distance through the
air by the intermediary of the luminous ether. But electric influence
can hardly be used, as the distances it would allow us to traverse
would be much too restricted, and electrostatic actions are often very
erratic. The phenomena of induction, which are very regular and
insensible to the variations of the atmosphere, have, on the other
hand, for a long time appeared serviceable for telegraphic purposes.
We might find, in a certain number of the attempts just mentioned, a
partial employment of these phenomena. Lindsay, for instance, in his
project of communication across the sea, attributed to them a
considerable rôle. These phenomena even permitted a true telegraphy
without intermediary wire between the transmitter and the receiver, at
very restricted distances, it is true, but in peculiarly interesting
conditions. It is, in fact, owing to them that C. Brown, and later
Edison and Gilliland, succeeded in establishing communications with
trains in motion.
Mr Willoughby S. Smith and Mr Charles A. Stevenson also undertook
experiments during the last twenty years, in which they used
induction, but the most remarkable attempts are perhaps those of
Professor Emile Rathenau. With the assistance of Professor Rubens and
of Herr W. Rathenau, this physicist effected, at the request of the
German Ministry of Marine, a series of researches which enabled him,
by means of a compound system of conduction and induction by
alternating currents, to obtain clear and regular communications at a
distance of four kilometres. Among the precursors also should be
mentioned Graham Bell; the inventor of the telephone thought of
employing his admirable apparatus as a receiver of induction phenomena
transmitted from a distance; Edison, Herr Sacher of Vienna, M. Henry
Dufour of Lausanne, and Professor Trowbridge of Boston, also made
interesting attempts in the same direction.
In all these experiments occurs the idea of employing an oscillating
current. Moreover, it was known for a long time--since, in 1842, the
great American physicist Henry proved that the discharges from a
Leyden jar in the attic of his house caused sparks in a metallic
circuit on the ground floor--that a flux which varies rapidly and
periodically is much more efficacious than a simple flux, which latter
can only produce at a distance a phenomenon of slight intensity. This
idea of the oscillating current was closely akin to that which was at
last to lead to an entirely satisfactory solution: that is, to a
solution which is founded on the properties of electric waves.
§ 5
Having thus got to the threshold of the definitive edifice, the
historian, who has conducted his readers over the two parallel routes
which have just been marked out, will be brought to ask himself
whether he has been a sufficiently faithful guide and has not omitted
to draw attention to all essential points in the regions passed
through.
Ought we not to place by the side, or perhaps in front, of the authors
who have devised the practical appliances, those scholars who have
constructed the theories and realised the laboratory experiments of
which, after all, the apparatus are only the immediate applications?
If we speak of the propagation of a current in a material medium, can
one forget the names of Fourier and of Ohm, who established by
theoretical considerations the laws which preside over this
propagation? When one looks at the phenomena of induction, would it
not be just to remember that Arago foresaw them, and that Michael
Faraday discovered them? It would be a delicate, and also a rather
puerile task, to class men of genius in order of merit. The merit of
an inventor like Edison and that of a theorist like Clerk Maxwell have
no common measure, and mankind is indebted for its great progress to
the one as much as to the other.
Before relating how success attended the efforts to utilise electric
waves for the transmission of signals, we cannot without ingratitude
pass over in silence the theoretical speculations and the work of pure
science which led to the knowledge of these waves. It would therefore
be just, without going further back than Faraday, to say how that
illustrious physicist drew attention to the part taken by insulating
media in electrical phenomena, and to insist also on the admirable
memoirs in which for the first time Clerk Maxwell made a solid bridge
between those two great chapters of Physics, optics and electricity,
which till then had been independent of each other. And no doubt it
would be impossible not to evoke the memory of those who, by
establishing, on the other hand, the solid and magnificent structure
of physical optics, and proving by their immortal works the undulatory
nature of light, prepared from the opposite direction the future
unity. In the history of the applications of electrical undulations,
the names of Young, Fresnel, Fizeau, and Foucault must be inscribed;
without these scholars, the assimilation between electrical and
luminous phenomena which they discovered and studied would evidently
have been impossible.
Since there is an absolute identity of nature between the electric and
the luminous waves, we should, in all justice, also consider as
precursors those who devised the first luminous telegraphs. Claude
Chappe incontestably effected wireless telegraphy, thanks to the
luminous ether, and the learned men, such as Colonel Mangin, who
perfected optical telegraphy, indirectly suggested certain
improvements lately introduced into the present method.
But the physicist whose work should most of all be put in evidence is,
without fear of contradiction, Heinrich Hertz. It was he who
demonstrated irrefutably, by experiments now classic, that an electric
discharge produces an undulatory disturbance in the ether contained in
the insulating media in its neighbourhood; it was he who, as a
profound theorist, a clever mathematician, and an experimenter of
prodigious dexterity, made known the mechanism of the production, and
fully elucidated that of the propagation of these electromagnetic
waves.
He must naturally himself have thought that his discoveries might be
applied to the transmission of signals. It would appear, however, that
when interrogated by a Munich engineer named Huber as to the
possibility of utilising the waves for transmissions by telephone, he
answered in the negative, and dwelt on certain considerations relative
to the difference between the periods of sounds and those of
electrical vibrations. This answer does not allow us to judge what
might have happened, had not a cruel death carried off in 1894, at the
age of thirty-five, the great and unfortunate physicist.
We might also find in certain works earlier than the experiments of
Hertz attempts at transmission in which, unconsciously no doubt,
phenomena were already set in operation which would, at this day, be
classed as electric oscillations. It is allowable no doubt, not to
speak of an American quack, Mahlon Loomis, who, according to Mr Story,
patented in 1870 a project of communication in which he utilised the
Rocky Mountains on one side and Mont Blanc on the other, as gigantic
antennae to establish communication across the Atlantic; but we cannot
pass over in silence the very remarkable researches of the American
Professor Dolbear, who showed, at the electrical exhibition of
Philadelphia in 1884, a set of apparatus enabling signals to be
transmitted at a distance, which he described as "an exceptional
application of the principles of electrostatic induction." This
apparatus comprised groups of coils and condensers by means of which
he obtained, as we cannot now doubt, effects due to true electric
waves.
Place should also be made for a well-known inventor, D.E. Hughes, who
from 1879 to 1886 followed up some very curious experiments in which
also these oscillations certainly played a considerable part. It was
this physicist who invented the microphone, and thus, in another way,
drew attention to the variations of contact resistance, a phenomenon
not far from that produced in the radio-conductors of Branly, which
are important organs in the Marconi system. Unfortunately, fatigued
and in ill-health, Hughes ceased his researches at the moment perhaps
when they would have given him final results.
In an order of ideas different in appearance, but closely linked at
bottom with the one just mentioned, must be recalled the discovery of
radiophony in 1880 by Graham Bell, which was foreshadowed in 1875 by
C.A. Brown. A luminous ray falling on a selenium cell produces a
variation of electric resistance, thanks to which a sound signal can
be transmitted by light. That delicate instrument the radiophone,
constructed on this principle, has wide analogies with the apparatus
of to-day.
§ 6
Starting from the experiments of Hertz, the history of wireless
telegraphy almost merges into that of the researches on electrical
waves. All the progress realised in the manner of producing and
receiving these waves necessarily helped to give rise to the
application already indicated. The experiments of Hertz, after being
checked in every laboratory, and having entered into the strong domain
of our most certain knowledge, were about to yield the expected fruit.
Experimenters like Sir Oliver Lodge in England, Righi in Italy,
Sarrazin and de la Rive in Switzerland, Blondlot in France, Lecher in
Germany, Bose in India, Lebedeff in Russia, and theorists like M.H.
Poincaré and Professor Bjerknes, who devised ingenious arrangements or
elucidated certain points left dark, are among the artisans of the
work which followed its natural evolution.
It was Professor R. Threlfall who seems to have been the first to
clearly propose, in 1890, the application of the Hertzian waves to
telegraphy, but it was certainly Sir W. Crookes who, in a very
remarkable article in the _Fortnightly Review_ of February 1892,
pointed out very clearly the road to be followed. He even showed in
what conditions the Morse receiver might be applied to the new system
of telegraphy.
About the same period an American physicist, well known by his
celebrated experiments on high frequency currents--experiments, too,
which are not unconnected with those on electric oscillations,--M.
Tesla, demonstrated that these oscillations could be transmitted to
more considerable distances by making use of two vertical antennae,
terminated by large conductors.
A little later, Sir Oliver Lodge succeeded, by the aid of the coherer,
in detecting waves at relatively long distances, and Mr Rutherford
obtained similar results with a magnetic indicator of his own
invention.
An important question of meteorology, the study of atmospheric
discharges, at this date led a few scholars, and more particularly the
Russian, M. Popoff, to set up apparatus very analogous to the
receiving apparatus of the present wireless telegraphy. This comprised
a long antenna and filings-tube, and M. Popoff even pointed out that
his apparatus might well serve for the transmission of signals as soon
as a generator of waves powerful enough had been discovered.
Finally, on the 2nd June 1896, a young Italian, born in Bologna on the
25th April 1874, Guglielmo Marconi, patented a system of wireless
telegraphy destined to become rapidly popular. Brought up in the
laboratory of Professor Righi, one of the physicists who had done most
to confirm and extend the experiments of Hertz, Marconi had long been
familiar with the properties of electric waves, and was well used to
their manipulation. He afterwards had the good fortune to meet Sir
William (then Mr) Preece, who was to him an adviser of the highest
authority.
It has sometimes been said that the Marconi system contains nothing
original; that the apparatus for producing the waves was the
oscillator of Righi, that the receiver was that employed for some two
or three years by Professor Lodge and Mr Bose, and was founded on an
earlier discovery by a French scholar, M. Branly; and, finally, that
the general arrangement was that established by M. Popoff.
The persons who thus rather summarily judge the work of M. Marconi
show a severity approaching injustice. It cannot, in truth, be denied
that the young scholar has brought a strictly personal contribution to
the solution of the problem he proposed to himself. Apart from his
forerunners, and when their attempts were almost unknown, he had the
very great merit of adroitly arranging the most favourable
combination, and he was the first to succeed in obtaining practical
results, while he showed that the electric waves could be transmitted
and received at distances enormous compared to those attained before
his day. Alluding to a well-known anecdote relating to Christopher
Columbus, Sir W. Preece very justly said: "The forerunners and rivals
of Marconi no doubt knew of the eggs, but he it was who taught them to
make them stand on end." This judgment will, without any doubt, be the
one that history will definitely pronounce on the Italian scholar.
§ 7
The apparatus which enables the electric waves to be revealed, the
detector or indicator, is the most delicate organ in wireless
telegraphy. It is not necessary to employ as an indicator a
filings-tube or radio-conductor. One can, in principle, for the purpose
of constructing a receiver, think of any one of the multiple effects
produced by the Hertzian waves. In many systems in use, and in the new
one of Marconi himself, the use of these tubes has been abandoned and
replaced by magnetic detectors.
Nevertheless, the first and the still most frequent successes are due
to radio-conductors, and public opinion has not erred in attributing
to the inventor of this ingenious apparatus a considerable and almost
preponderant part in the invention of wave telegraphy.
The history of the discovery of radio-conductors is short, but it
deserves, from its importance, a chapter to itself in the history of
wireless telegraphy. From a theoretical point of view, the phenomena
produced in those tubes should be set by the side of those studied by
Graham Bell, C.A. Brown, and Summer Tainter, from the year 1878
onward. The variations to which luminous waves give rise in the
resistance of selenium and other substances are, doubtless, not
unconnected with those which the electric waves produce in filings. A
connection can also be established between this effect of the waves
and the variations of contact resistance which enabled Hughes to
construct the microphone, that admirable instrument which is one of
the essential organs of telephony.
More directly, as an antecedent to the discovery, should be quoted the
remark made by Varley in 1870, that coal-dust changes in conductivity
when the electromotive force of the current which passes through it is
made to vary. But it was in 1884 that an Italian professor, Signor
Calzecchi-Onesti, demonstrated in a series of remarkable experiments
that the metallic filings contained in a tube of insulating material,
into which two metallic electrodes are inserted, acquire a notable
conductivity under different influences such as extra currents,
induced currents, sonorous vibrations, etc., and that this
conductivity is easily destroyed; as, for instance, by turning the
tube over and over.
In several memoirs published in 1890 and 1891, M. Ed. Branly
independently pointed out similar phenomena, and made a much more
complete and systematic study of the question. He was the first to
note very clearly that the action described could be obtained by
simply making sparks pass in the neighbourhood of the radio-conductor,
and that their great resistance could be restored to the filings by
giving a slight shake to the tube or to its supports.
The idea of utilising such a very interesting phenomenon as an
indicator in the study of the Hertzian waves seems to have occurred
simultaneously to several physicists, among whom should be especially
mentioned M. Ed. Branly himself, Sir Oliver Lodge, and MM. Le Royer
and Van Beschem, and its use in laboratories rapidly became quite
common.
The action of the waves on metallic powders has, however, remained
some what mysterious; for ten years it has been the subject of
important researches by Professor Lodge, M. Branly, and a very great
number of the most distinguished physicists. It is impossible to
notice here all these researches, but from a recent and very
interesting work of M. Blanc, it would seem that the phenomenon is
allied to that of ionisation.
§ 8
The history of wireless telegraphy does not end with the first
experiments of Marconi; but from the moment their success was
announced in the public press, the question left the domain of pure
science to enter into that of commerce. The historian's task here
becomes different, but even more delicate; and he will encounter
difficulties which can be only known to one about to write the history
of a commercial invention.
The actual improvements effected in the system are kept secret by the
rival companies, and the most important results are patriotically left
in darkness by the learned officers who operate discreetly in view of
the national defence. Meanwhile, men of business desirous of bringing
out a company proclaim, with great nourish of advertisements, that
they are about to exploit a process superior to all others.
On this slippery ground the impartial historian must nevertheless
venture; and he may not refuse to relate the progress accomplished,
which is considerable. Therefore, after having described the
experiments carried out for nearly ten years by Marconi himself, first
across the Bristol Channel, then at Spezzia, between the coast and the
ironclad _San Bartolommeo_, and finally by means of gigantic apparatus
between America and England, he must give the names of those who, in
the different civilised countries, have contributed to the improvement
of the system of communication by waves; while he must describe what
precious services this system has already rendered to the art of war,
and happily also to peaceful navigation.
From the point of view of the theory of the phenomena, very remarkable
results have been obtained by various physicists, among whom should be
particularly mentioned M. Tissot, whose brilliant studies have thrown
a bright light on different interesting points, such as the rôle of
the antennae. It would be equally impossible to pass over in silence
other recent attempts in a slightly different groove. Marconi's
system, however improved it may be to-day, has one grave defect. The
synchronism of the two pieces of apparatus, the transmitter and the
receiver, is not perfect, so that a message sent off by one station
may be captured by some other station. The fact that the phenomena of
resonance are not utilised, further prevents the quantity of energy
received by the receiver from being considerable, and hence the
effects reaped are very weak, so that the system remains somewhat
fitful and the communications are often disturbed by atmospheric
phenomena. Causes which render the air a momentary conductor, such as
electrical discharges, ionisation, etc., moreover naturally prevent
the waves from passing, the ether thus losing its elasticity.
Professor Ferdinand Braun of Strasburg has conceived the idea of
employing a mixed system, in which the earth and the water, which, as
we have seen, have often been utilised to conduct a current for
transmitting a signal, will serve as a sort of guide to the waves
themselves. The now well-known theory of the propagation of waves
guided by a conductor enables it to be foreseen that, according to
their periods, these waves will penetrate more or less deeply into the
natural medium, from which fact has been devised a method of
separating them according to their frequency. By applying this theory,
M. Braun has carried out, first in the fortifications of Strasburg,
and then between the island of Heligoland and the mainland,
experiments which have given remarkable results. We might mention also
the researches, in a somewhat analogous order of ideas, by an English
engineer, Mr Armstrong, by Dr Lee de Forest, and also by Professor
Fessenden.
Having thus arrived at the end of this long journey, which has taken
him from the first attempts down to the most recent experiments, the
historian can yet set up no other claim but that of having written the
commencement of a history which others must continue in the future.
Progress does not stop, and it is never permissible to say that an
invention has reached its final form.
Should the historian desire to give a conclusion to his labour and
answer the question the reader would doubtless not fail to put to him,
"To whom, in short, should the invention of wireless telegraphy more
particularly be attributed?" he should certainly first give the name
of Hertz, the genius who discovered the waves, then that of Marconi,
who was the first to transmit signals by the use of Hertzian
undulations, and should add those of the scholars who, like Morse,
Popoff, Sir W. Preece, Lodge, and, above all, Branly, have devised the
arrangements necessary for their transmission. But he might then
recall what Voltaire wrote in the _Philosophical Dictionary_:
"What! We wish to know what was the exact theology of Thot, of
Zerdust, of Sanchuniathon, of the first Brahmins, and we are ignorant
of the inventor of the shuttle! The first weaver, the first mason, the
first smith, were no doubt great geniuses, but they were disregarded.
Why? Because none of them invented a perfected art. The one who
hollowed out an oak to cross a river never made a galley; those who
piled up rough stones with girders of wood did not plan the Pyramids.
Everything is made by degrees and the glory belongs to no one."
To-day, more than ever, the words of Voltaire are true: science
becomes more and more impersonal, and she teaches us that progress is
nearly always due to the united efforts of a crowd of workers, and is
thus the best school of social solidarity.