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K J- C fc .. WitUOUCHBY 















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Past President, Institution of Electrical Engineers ; 
President, Institution of Civil Engineers, 

&c., &c., 

The First Constructor of a Practical 
Wireless Telegraph, 





in 1897 there was a great flutter in the dove-cotes 
of telegraphy, and holders of the many millions of telegraph 
securities, and those interested in the allied industries, 
began to be alarmed for the safety of their property. 
Mysterious paragraphs about the few, Wireless, or Space 
Telegraphy, as it was variously called, kept appearing in 
the papers ; and the electrical profession itself certainly 
some leading members of it seemed disposed to accept 
implicitly the new marvels, without the grain of salt usual 
and proper on such occasions. 

In a lecture on Submarine Telegraphy at the Imperial 
Institute (February 15, 1897), Professor Ayrton said: "I 
have told you about the past and about the present. What 
about the future *? Well, there is no doubt the day will 
come, maybe when you and I are forgotten, when copper 
wires, gutta-percha coverings, and iron sheathings will be 
relegated to the Museum of Antiquities. Then, when a 
person wants to telegraph to a friend, he knows not where, 
he will call in an electro-magnetic voice, which will be 

viii PREFACE. 

heard loud by him who has the electro-magnetic ear, but 
will be silent to every one else. He will call, ' Where are 
you 1 ' and the reply will come, ' I am at the bottom of the 
coal-mine,' or ' Crossing the Andes,' or ' In the middle of 
the Pacific ' ; or perhaps no reply will come at all, and he 
may then conclude the friend is dead." 

Soon after, in the course of a debate in the House of 
Commons (April 2, 1897) on the Telephone monopoly, one 
of the speakers said : " It would be unwise on the part of 
the Post Office to enter into any very large undertakings in 
respect of laying down telephone wires until they had as- 
certained what was likely to be the result of the Eontgen 
form of telegraph, which, if successful, would revolutionise 
our telephonic and telegraphic systems." 

When cautious men of science spoke, or should I not 
say dreamt thus, and when sober senators accepted the 
dream as a reality and proceeded to legislate upon it, we 
can imagine the ideas that were passing in the minds of 
those of the general public who gave the subject a thought. 
Well, two years have now elapsed, and the unbounded 
potentialities of the new telegraphy have been whittled 
down by actual experiment to small practical though still 
very important proportions ; and so, those interested in the 
old order can sleep in peace, and can go on doing so for a 
long time yet to come. 

Having in the course of many years' researches in electric 
lore collected a mass of materials on this subject for the 
idea embodied in the new telegraphy is by no means new 
and having been a close observer of its recent and startling 
developments, I have thought that a popular account of its 


origin and progress would not now be uninteresting. This 
I have accordingly attempted in the following pages. 

At an early stage in the evolution of our subject, objec- 
tion was taken to the epithet Telegraphy without Wires, 
or, briefly, Wireless Telegraphy, as a misnomer (e.g., the 
'Builder/ March 17, 1855, p. 132), and in recent times 
the objection has been repeated. Induction, Space, and 
Ethereal Telegraphy have been suggested, but though 
accurate for certain forms, they are not comprehensive 
enough. A better name would be Telegraphy without 
Connecting Wires, which has also been suggested, but it is 
too cumbrous an awkward mouthful. Pending the dis- 
covery of a better one, I have adhered to the original 
designation Wireless Telegraphy, which actually is the 
popular one, and for which, moreover, I have the high 
sanction of her Majesty's Attorney-General. 

In the course of a discussion on Mr W. H. Preece's 
paper on Electric Signalling without Wires (' Journal 
Society of Arts,' February 23, 1894), Sir Eichard Webster 
laid down the law thus : " I think the objection to the 
title of the paper is rather hypercritical, because ordinary 
people always understand telegraphing by wire as meaning 
through the wire, going from one station to the other ; and 
these parallel wires, not connected, would rather be looked 
upon as parts of the sending and receiving instruments. I 
hope, therefore, that the same name will be adhered to in 
any further development of the subject." If thus the name 
be allowable in Mr Preece's case where, to bridge a space 
of, say, one mile, two parallel wires, each theoretically one 
mile long, are requisite, or double the amount required in 


the old form of telegraphy, it cannot be objected to in any 
of the other proposals which are described in these pages, 
certainly not to the Marconi system, where a few feet of 
wire at each end suffice for one mile of space, or, to put it 
accurately, where the height of the vertical wires varies as 
the square root of the distance to be signalled over. 

At the outset of my task I was met with the difficulty 
of arranging my materials whether in simple chronological 
order, or classified under heads, as Conduction, Induction, 
Wave, and Other or Miscellaneous Methods. Both have 
their advantages and disadvantages, but after consideration 
I decided to follow in the main the chronological order as 
the better of the two for a history which is intended to be 
a simple record of what has been done or attempted in the 
last sixty years by the many experimenters who have 
attacked the problem or contributed in any way to its 

Having settled this point, the further question of sub- 
division presented itself, and as the materials did not lend 
themselves to arrangement in chapters I decided to divide 
the text into periods. The first I have called The Possible 
Period, which deals with first suggestions and empirical 
methods of experiment, and which, by reason of the want 
of delicacy in the instruments then available, may not 
inaccurately be compared with the Palaeolithic period in 
geology. The second is The Practicable (or Neolithic) 
Period, when the conditions of the problem came to be 
better understood, and more delicate instruments of research 
were at hand. The third The Practical Period brings 
the subject up to date, and deals with the proposals of 


Preece (Electro - Magnetic), of Willoughby Smith (Con- 
ductive), and of Marconi (Hertzian), which are to-day in 
actual operation. 

The whole concludes with five Appendices, containing 
much necessary information for which I could not conveni- 
ently find room in the body of the work. Appendix A 
deals with the philosophic views of the relation between 
electricity and light before and after Hertz, who, for the 
first time, showed them to be identical in kind, differing 
only in the degree of their wave-lengths. Appendix B 
gives in a popular form the modern views of electric 
currents consequent on the discoveries of Clerk-Maxwell, 
Hertz, and their disciples. Appendix C reproduces the 
greater part of Professor Branly's classic paper on his 
discovery of the Coherer principle, which is one of the 
foundation-stones of the Marconi system. Appendix 1) 
contains a very interesting correspondence between myself 
and Prof. Hughes, F.K.S., which came too late for insertion 
in the body of the work, and which is too important from 
the historical point of view to be omitted. 

In Appendix E Mr Marconi's patent specification is 
reproduced, as, besides being historically interesting as the 
first patent for a telegraph of the Hertzian order, it is in 
itself a marvel of completeness. As the apparatus is there 
described, so it is used to-day after three years' rigorous 
experimentation, the only alterations being in points of 
detail a finer adjustment of means to ends. This says 
much for the constructive genius of the young inventor, 
and bodes well for the survival of his system in the 
struggle for existence in which it is now engaged. 


In the presentation of my materials I have allowed, as 
far as possible, the various authors to speak in their own 
words, merely condensing freely and, where necessary, 
translating obsolete words and phrases into modern technical 
language. This course in a historical work is, I think, 
preferable to obtruding myself as their interpreter. For 
the same reason I have given in the text, or in footnotes 
thereto, full references, so that the reader who desires to 
consult the original sources can readily do so. 

I seem to hear the facetious critic exclaim, " Why, this 
is all scissors and paste." So it is, good sir, much of it; 
and so is all true history when you delete the fictions with 
which many historians embellish their facts. What one 
person said or what another did is not altered by the pres- 
ence or absence of quotation marks. However, the only 
credit I claim is that due to collecting, condensing, and pre- 
senting my facts in a readable form no light task, and if 
my critics will award me this I will be satisfied. 

Since the following pages were written, two excellent 
contributions have been made by Prof. Oliver Lodge 
and Mr Sydney Evershed in papers read before the Insti- 
tution of Electrical Engineers, December 8 and 22, 1898. 
These will be found in No. 137 of the 'Journal,' and, 
together with the discussion which followed, should be 
studied by all interested in this fascinating subject. Mr 
Marconi has followed up these papers with one on his own 
method, which was read before the Institution on the 2nd 
of March last, and was repeated by general request on the 
16th idem. He does not carry the matter farther than I 
have done in the text, but still the paper is worth reading 


if only as an exposition in a nutshell of his beautiful 

As a Frontispiece I give a group of twelve portraits of 
eminent men who may be fitly called the Arch-builders of 
Wireless Telegraphy. At the top stands Oersted (Den- 
mark), who first showed the connection between electricity 
and magnetism. Then follow in order of time Ampere 
(France), Faraday (England), and Henry (America), who 
explained and extended the principles of the new science of 
electro-magnetism. Then come Clerk-Maxwell (England) 
and Hertz (Germany), who showed the relation between 
electricity and light, the one theoretically, and the other 
by actual demonstration. These are followed by Branly 
(France), Lodge (England), and Eighi (Italy), whose dis- 
coveries have made possible the invention of Marconi. 
The last three are portraits of Preece and Willoughby 
Smith (England) and Marconi (Italy), who divide between 
them the honour of establishing the first practical lines of 
wireless telegraph each typical of a different order. 

September 1899. 





EDWARD DAVY 1838 . . 6 

PROFESSOR MORSE 1842 .... 10 

JAMES BOWMAN LINDSAY 1843 . . . .13 

j. w. WILKINS 1845 ..... 32 


NESSY BROOKE) 1849 . . . .39 

E. AND H. HIGHTON 1852-72 . . . .40 

G. E. DERING 1853 ..... 48 

JOHN HAWORTH 1862 . . . . .55 

J. H. MOWER 1868 ..... 70 

M. BOURBOUZE 1870 ..... 71 

MAHLOX LOOMIS 1872 . ... 73 






PROFESSOR GRAHAM BELL 1882 . . \ . 96 

PROFESSOR A. E. DOLBEAR 1883 . . . .99 

T. A. EDISON 1885 '. . . .103 

W. F. MELHUISH 1890 . . . ..- .114 

C. A. STEVENSON 1892 . . * " . 122 




w. H. PREECE'S METHOD . . . . ; . 136 


G. MARCONI'S METHOD .... . '. . .177 












RAPHY, 1879-1886 -. . . .... 289 



INDEX . 321 




"Awhile forbear, 

Nor scorn man's efforts at a natural growth, 
Which in some distant age may hope to find 
Maturity, if not perfection. " 


JUST mentioning en passant the sympathetic needle and 
sympathetic flesh telegraphs of the sixteenth and seven- 
teenth centuries, a full account of which will be found in 
my 'History of Electric Telegraphy to 1837' (chap, i.), 
we come to the year 1795 for the first glimmerings of 
telegraphy without wires. Salva, who was an eminent 
Spanish physicist, and the inventor of the first electro- 
chemical telegraph, has the following bizarre passage in 
his paper " On the Application of Electricity to Teleg- 
raphy," read before the Academy of Sciences, Barcelona, 
December 16, 1795. 

After showing how insulated wires may be laid under 


the seas, and the water used instead of return wires, he 
goes on to say : "If earthquakes be caused by electricity 
going from one point charged positively to another point 
charged negatively, as Bertolon has shown in his ' Elec- 
tricite des Meteores ' (vol. i. p. 273), one does not even want 
a cable to send across the sea a signal arranged beforehand. 
One could, for example, arrange at Mallorca an area of 
earth charged with electricity, and at 'Alicante a similar 
space charged with the opposite electricity, with a wire 
going to, and dipping into, the sea. On leading another 
wire from the sea-shore to the electrified spot at Mallorca, 
the communication between the two charged surfaces would 
be complete, for the electric fluid would traverse the sea, 
which is an excellent conductor, and indicate by the spark 
the desired signal." l 

Another early telegraph inventor and eminent physi- 
ologist, Sommerring of Munich, has an experiment which, 
under more favourable conditions of observation, might 
easily have resulted in the suggestion at this early date 
of signalling through and by water alone. Dr Hamel 2 
tells us that Sommerring, on the 5th of June 1811, and 
at the suggestion of his friend, Baron Schilling, tried the 
action of his telegraph whilst the two conducting cords 
were each interrupted by water contained in wooden tubs. 
The signals appeared just as well as if no water had been 
interposed, but they ceased as soon as the water in the 
tubs was connected by a wire, the current then returning 
by this shorter way. 

Now here we have, in petto, all the conditions necessary 

1 Later on in these pages we shall see that Salve's idea is after 
all not so extravagant as it seems. We now know that large spaces 
of the earth can be electrified, giving rise to the phenomenon of 
"bad earth," so well known to telegraph officials. 

2 Historical Account of the Introduction of the Galvanic and 
Electro-magnetic Telegraph into England, Cooke's Keprint, p. 17. 


for an experiment of the kind with which we are dealing, 
and had it been possible for Sommerring to have employed 
a more delicate indicator than his water-decomposing appar- 
atus he would probably have noticed that, notwithstanding 
the shorter way, some portion of the current still went the 
longer way ; and this fact could hardly have failed to suggest 
to his acute and observant mind further experiments, which, 
as I have just said,' might easily have resulted in his recog- 
nition of the possibility of wireless telegraphy. 

Leaving the curious suggestion of Salva, which, though 
seriously meant, cannot be regarded as more than a jeu 
d'esprit a happy inspiration of genius and the what- 
might-have-come-of-it experiment of Sommerring, we come 
to the year 1838, when the first intelligent suggestion of a 
wireless telegraph was made by Steiuheil of Munich, one of 
the great pioneers of electric telegraphy on the Continent. 

The possibility of signalling without wires was in a 
manner forced upon him. While he was engaged in estab- 
lishing his beautiful system of telegraphy in Bavaria, Gauss, 
the celebrated German philosopher, and himself a telegraph 
inventor, suggested to him that the two rails of a railway 
might be utilised as telegraphic conductors. In July 1838 
Steinheil tried the experiment on the Nurmberg-Furth 
railway, but was unable to obtain an insulation of the rails 
sufficiently good for the current to Teach from one station 
to the other. The great conductibility with which he 
found that the earth was endowed led him to presume that 
it would be possible to employ it instead of the return wire 
or wires hitherto used. The trials that he made in order 
to prove the accuracy of this conclusion were followed by 
complete success ; and he then introduced into electric teleg- 
raphy one of its greatest improvements the earth circuit. 1 

1 For the use of the earth circuit before Steinheil's accidental dis- 
covery, see my 'History of Electric Telegraphy to 1837,' pp. 343-345. 


Steinheil then goes on to say : " The inquiry into the 
laws of dispersion, according to which the ground, whose 
mass is unlimited, is acted upon by the passage of the 
galvanic current, appeared to be a subject replete with in- 
terest. The galvanic excitation cannot be confined to the 
portions of earth situated between the two ends of the wire ; 
on the contrary, it cannot but extend itself indefinitely, and 
it therefore only depends on the law that obtains in this 
excitation of the ground, and the distance of the exciting 
terminations of the wire, whether it is necessary or not to 
have any metallic communication at all for candying on 
telegraphic intercourse. 

" An apparatus can, it is true, be constructed in which 
the inductor, having no other metallic connection with the 
multiplier than the excitation transmitted through the 
ground, shall produce galvanic currents in that multiplier 
sufficient to cause a visible deflection of the bar. This is a 
hitherto unobserved fact, and may be classed amongst the 
most extraordinary phenomena that science has revealed to 
us. It only holds good, however, for small distances ; and 
it must be left to the future to decide whether we shall ever 
succeed in telegraphing at great distances without any 
metallic communication at all. My experiments prove that 
such a thing is possible up to distances of 50 feet. For 
greater distances we can only conceive it feasible by aug- 
menting the power of the galvanic induction, or by ap- 
propriate multipliers constructed for the purpose, or, in 
conclusion, by increasing the surface of contact presented 
by the ends of the multipliers. At all events, the phe- 
nomenon merits our best attention, and its influence will not 
perhaps be altogether overlooked in the theoretic views we 
may form with regard to galvanism itself." l 

In another place, discussing the same subject, Steinheil 
1 Sturgeon's Annals of Electricity, vol. iii. p. 450. 


says : " We cannot conjure up gnomes at will to convey 
our thoughts through the earth. Nature has prevented 
this. 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 50 feet, 
only exceedingly small effects can be produced by the most 
powerful electrical effect at the point of excitation. Had 
we means which could stand in the same relation to elec- 
tricity 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 this end." l 

Steinheil proposed another means of signalling without 
wires, which is curiously apropos of Professor Graham 
Bell's photophone. In his classic paper on "Telegraphic 
Communication, especially by Means of Galvanism," he 
says : " Another possible method of bringing about 
transient movements at great distances, without any inter- 
vening artificial conductor, is furnished by radiant heat, 
when directed by means of condensing mirrors upon a 
thermo-electric pile. A galvanic current is called into play, 
which in its turn is employed to produce declinations of a 
magnetic needle. The difficulties attending the construc- 
tion of such an instrument, though certainly considerable, 
are not in themselves insuperable. Such a telegraph, 
however, would only have this advantage over those 
[semaphores] based on optical principles namely, that it 
does not require the constant attention of the observer; 
but, like the optical one, it would cease to act during 
cloudy weather, and hence partakes of the intrinsic defects 
of all semaphoric methods." 2 

1 Die Anwendung des Electromagnetismus, 1873, p. 172. "We now 
have these means in "the electric eye"of Hertz ! See pp. 181,256m/ra. 

2 Sturgeon's Annals of Electricity, March 1839. Acting on this 
suggestion, in June 1880 the present writer, while stationed at 



While arranging, in 1883, the Edward Davy MSS., now 
in the library of the Institution of Electrical Engineers, 
the present writer discovered two passages which he at first 
took to have reference to some kind of telephonic relay; 
but on closer consideration it would appear that Davy had 
in view some contrivance based on the conjoint use of 
sound and electricity, much as Steinheil suggested the joint 
use of electricity and heat. The following are the passages 
to which I refer : 

At the end of a long critical examination of Cooke and 
Wheatstone's first patent of June 12, 1837, he says: "I 
have lately found that there is a peculiar way of propagat- 
ing signals between the most distant places by self-acting 
means, and without the employment of any conducting 
wires at all. It is to be done partly by electricity, but 
combined with another principle, of the correctness of 
which there can be no doubt. But until I know what 
encouragement the other 1 will meet with I shall take no 

Teheran, Persia, and while yet ignorant of Professor Bell's method, 
worked out for himself a photophone, or rather a tele-photophone, 
which will be found described in the 'Electrician,' February 26, 1881. 
On my temporary return to England in 1882, I found that as early 
as 1878 Mr A. C. Brown, of the Eastern Telegraph Company, was 
working at the photophone. In September of that year he sub- 
mitted his plans to Prof. Bell, who afterwards said of them : " To 
Mr Brown is undoubtedly due the honour of having distinctly and 
independently formulated the conception of using an undulatory 
beam of light, in contradistinction to a merely intermittent one, in 
connection with selenium and a telephone, and of having devised 
apparatus, though of a crude nature, for carrying it into execution " 
('Jour. Inst. Elec. Engs.,' vol. ix. p. 404). Indeed the photophone is 
as much the invention of Mr Brown as of Prof. Bell, who, however, 
has all the credit for it in popular estimation. 

1 That is, his chemical recording telegraph. See my ' History of 
Electric Telegraphy,' London, 1884, p. 379. 


steps in this, as it may happen there will be other rivals. 
To give you a general idea of it, a bell may be rung at 
the first station, and then in the next instant a bell will 
ring at the next station a mile off, and so on for an 
unlimited series, though there is nothing between them 
but the plain earth and air ! At the termination of the 
series, the signals may be given in letters, as in the present 

Again, in a paper of numbered miscellaneous memor- 
anda, ^o. 20 reads as follows : " 20. The plan proposed 
(101) of propagating communications by the conjoint 
agency of sound and electricity the original sound pro- 
ducing vibrations which cause sympathetic vibrations in a 
unison -sounding apparatus at a distance, this last vibra- 
tion causing a renewing wire to dip 1 and magnetise soft 
iron so as to repeat the sound, and so on in unlimited 

It is not easy to say from these passages (which are all 
we could find on the subject) what plan Davy had in 
contemplation. In the first quotation he speaks of bells, 
for which we may read a powerful trumpet at one end, 
and a concave reflector to focus the sound at the other 
end; or some arrangement like the compressed-air tele- 
phone, proposed by Captain Taylor, R.N., in 1844 ; or 
the modern siren; or, in short, any means of producing 
sharp concussions of the air, such as were known in his 
day. Let us suppose he used any of these methods for 
projecting sound waves, then, at the focus of the distant 
reflector he may have designed a "renewing wire," so 
delicately poised as to respond to the vibration, and so 

1 I.e., causing a relay to close a local circuit containing an electro- 
magnet. Davy always spoke of the relay as the " renewer " or the 
" renewing wire " ; and by dip he meant to dip into mercury, or, as 
we say nowadays, to close the circuit. 


close a local circuit in which was included the electro- 
magnetic apparatus for recording the sound, or for renewing 
it as required. 

In- the second passage he speaks. of something on the 
principle of the tuning-fork. Now, tuning-forks in com- 
bination with reflectors may be practicable for short dis- 
tances, but it is difficult to see how their vibrations could 
be utilised, at the distance of a mile, for "causing a 
renewing wire to dip." 

However this may be, Davy's idea deserves at least 
this short notice in a history of early attempts at wireless 
telegraphy ; for, although hardly possible of realisation 
with the apparatus at his command, it is perfectly feasible 
in these days of megaphones and microphones. As regards 
its practical utility, that is a question for the future, as 
to which we prefer not to prophesy. 1 

Davy's idea was probably the result of an incautious 
dose of the Auticatelephor of Edwards, which made a 
great stir a few years previously, and which, at first sight, 
might be taken to be a telegraph without apparently any 
connecting medium. We take the following announcement 
from the ' Kaleidoscope ' of June 30, 1829 (p. 430) : 


" We have received several papers descriptive of a new 
and curious engine, with the above name, invented by Mr 
T. W. C. Edwards, Lecturer on Experimental Philosophy 

1 Such a plan as Davy's was again suggested, in 1881, by Signer 
Senlicq d' Andres (' Telegraphic Journal,' vol. ix. p. 126), who, however, 
proposed to use, instead of a renewing wire or relay, the mouthpiece 
of a microphonic speaker, rendered more sensitive by a contact lever 
with unequal arms. Mr A. R. Senuett has also worked at the idea 
in more recent years. His method is very clearly described in the 
'Jour. Inst. Elec. Engs.,' No. 137, p. 908. 


and Chemistry, and designed for the instantaneous convey- 
ance of intelligence to any distance. After noticing some 
of the greatest inventions of preceding times, Mr Edwards 
undertakes to demonstrate clearly and briefly, in the work 
which he has now in the press, 1 the practicability and 
facility of transmitting from London, instantaneously, to an 
agent at Edinburgh, Dublin, Paris, Vienna, St Petersburg, 
Constantinople, the Cape of Good Hope, Madras, Calcutta, 
&c., any question or message whatever, and of receiving 
back again at London, within the short space of one minute, 
an acknowledgment of the arrival of such question or 
message at the place intended, and a distinct answer to it in 
a few minutes. In principle this engine is altogether 
different from every kind of telegraph or semaphore, and 
requires neither intermediate station nor repetition. In its 
action it is totally unconnected with electricity, magnetism, 
galvanism, or any other subtle species of matter; .and 
although the communication from place to place is instan- 
taneous, and capable of ringing a bell, firing a gun, or 
hoisting a flag if required, yet this is not effected by the 
transit of anything whatever to and fro ; nor in the opera- 
tion is aught either audible or visible, except to the persons 
communicating. It may be proper, however, to state that a 
channel or way must previously be prepared, by sinking a 
series of rods of a peculiar description in the ground, or 
dropping them in the sea ; but these, after the first cost, 
will remain good for ages to come, if substantial when laid 
down." 2 

1 In 1883 we searched for this book in vain. Under the name T. 
W. C. Edwards we found in the British Museum Catalogue no less 
than twenty entries of translations from Greek authors, and of Greek 
and Latin grammars, &c. ; but nothing to show that the writer was 
either a natural philosopher or a chemist. 

2 See also the 'Mechanics' Magazine,' vol. xiii., First Series, 
p. 182. 


From the concluding words of this paragraph it would 
seem that the Auticatelephor was simply an application to 
telegraphy of pneumatic or hydraulic pressure in pipes 
cautiously styled " rods of a peculiar description." On this 
supposition the last sentence may be paraphrased thus : 
" It may be proper, however, to state that a channel or way 
must previously be prepared, by laying down a continuous 
series of hollow rods or tubes under the ground or along the 
sea-bottom." If our supposition be correct, and if Edwards 
contemplated the use of compressed air, his proposal was 
certainly novel ; but if he designed the use of compressed 
water, the idea was by no means new. Without going 
back to the old Roman plan of ^Eneas Tacticus, we have 
its revival by Brent and others towards the close of the 
last century, and the still more practical arrangements of 
Joseph Eramah in 1796, of Vallance in 1825, and of 
Jobard in 1827. 


The idea of a wireless telegraph next appears to have 
presented itself to Professor Morse. In a letter to the 
Secretary of the Treasury, which was laid before the 
House of Representatives on December 23, 1844, he 
says : 

"In the autumn of 1842, at the request of the American 
Institute, I undertook to give to the public in New York 
a demonstration of the practicability of my telegraph, by 
connecting Governor's Island with Castle Garden, a dis- 
tance of a mile ; and for this purpose I laid my wires 
properly insulated beneath the water. I had scarcely 
begun to operate, and had received but two or three 
characters, when my intentions were frustrated by the 



accidental destruction of a part of my conductors by a 
vessel, which drew them up on her anchor, and cut them 
off. In the moments of mortification I immediately de- 
vised a plan for avoiding such an accident in future, by 
so arranging my wires along the banks of the river as to 
cause the water itself to conduct the electricity across. 
The experiment, however, was deferred till I arrived in 
Washington; and on December 16, 1842, I tested my 
arrangement across the canal, and with success. The 
simple fact was then ascertained that electricity could be 
made to cross a river without other conductors than the 
water itself; but it was not until the last autumn that 
I had the leisure to make a series of experiments to ascer- 
tain the law of its passage. The following diagram will 
serve to explain the experiment : 

"A, B, c, D, are the banks of the river; N, p, is the 
battery ; G is the galvanometer ; w w, are the wires along 
the banks, connected with copper plates,/, g, h, i, which 
are placed in the water. When this arrangement is com- 
plete, the electricity, generated by the battery, passes from 
the positive pole, p, to the plate ^, 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, N. 



"The distance across the canal is 80 feet; on August 
24 the following were the results of the experiment : 

No. of the experiment. 







No. of cups in battery 







Length of conductors, w, w 
Degrees of motion of gal- 


131 & 41 




211 & 15 

Size of the copper plates, ) 
/, <7, ft, i f 

5 by 

1(5 by 
13 in. 

6 by 
5 in. 

5 by 

5 by 
21 ft. 

5 by 
21 ft. 

" Showing that electricity crosses the river, and in quan- 
tity in proportion to the size of the plates in the water. The 
distance of the plates on the same side of the river from 
each other also affects the result. Having ascertained the 
general fact, I was desirous of discovering the best practical 
distance at which to place my copper plates, and not having 
the leisure myself, I requested my friend Professor Gale to 
make the experiments for me. I subjoin his letter and the 
results. 1 

'"NEW YORK, Nov. 5th, 1844. 

" ' MY DEAR SIR, I send you herewith a copy of a 
series of results, obtained with four different-sized plates, 
as conductors to be used in crossing rivers. The batteries 
used were six cups of your smallest size, and one liquid 
used for the same throughout. I made several other series 
of experiments, but these I most rely on for uniformity and 
accuracy. You will see, from inspecting the table, that the 
distance along the shores should be three times greater than 
that from shore to shore across the stream ; at least, that 
four times the distance does not give any increase of 
power. I intend to repeat all these experiments under 

1 We omit the tables of results, as of no present value. They can 
be seen in Vail's book, quoted infra. 


more favourable circumstances, and will communicate to 
you the results. Very respectfully, L. D. GALE. 

" < Professor S. F. B. MORSE, 

Superintendent of Telegraphs' 

" As the results of these experiments, it would seem that 
there may be situations in which the arrangements I have 
made for passing electricity across rivers may be useful, 
although experience alone can determine whether lofty 
spars, on which the wires may be suspended, erected in the 
rivers, may not be deemed the most practical. The experi- 
ments made were but for a short distance ; in which, how- 
ever, the principle was fully proved to be correct. It has 
been applied under the direction of my able assistants, 
Messrs Vail and Eogers, across the Susquehanna river, at 
Havre-de-Grace, with complete success, a distance of nearly 
a mile." l 


The next to pursue the subject was J. B. Lindsay of 
Dundee, whose extensive labours in this, as well as in the 
department of electric lighting, have hitherto been little 
appreciated by the scientific world. Through the kind 
assistance of Dr Robert Sinclair of Dundee, I have lately 
collected a number of facts relating to this extraordinary 
man, and as I believe they will be new to most of my 
readers, I will draw largely from them in what follows. 2 

James Bowman Lindsay was born at Carmyllie, near 
Arbroath, on September 8, 1799, and but for the delicacy 

1 Tail's American Electro-Magnetic Telegraph, Philadelphia, 1845. 

2 Extracts from the writer's articles in the * Electrical Engineer,' 
vol. xxiii. pp. 21, 51. 


of his constitution would have been bred a farmer. At an 
early age he evinced a great taste for reading, and every 
moment that he could spare from his work as a linen- 
weaver was devoted to his favourite books. Often, indeed, 
he would be seen on his way to Arbroath with a web of 
cloth tied on his back and an open book in his hands ; and, 
after delivering the cloth and obtaining fresh materials for 
weaving, he would return to Carmyllie in the same fashion. 
Encouraged by these studious habits, Lindsay's parents 
wisely arranged that he should go to St Andrews Uni- 
versity. Accordingly, in 1821 he entered on his studies, 
and, self-taught though he had hitherto been, he soon made 
for himself a distinguished place among his fellow-students, 
particularly in the mathematical and physical sciences, in 
which departments, indeed, he became the first student of 
his time. Having completed the ordinary four years' 
course, Lindsay entered as a student of theology, and duly 
completed his studies in the Divinity Hall ; but he never 
presented himself for a licence, his habits of thought in- 
clining more to scientific than to theological pursuits. In 
the long summer vacations he generally returned to his 
occupation of weaving, though latterly he took up teaching, 
and thus enjoyed more time for the prosecution of his own 

Coming to Dundee in 1829, he was appointed Science 
and Mathematical Lecturer at the Watt Institution, then 
conducted by a Mr M'Intosh. Soon after, Alexander 
Maxwell, the historian of Dundee, became a pupil, and this 
is the picture he has left us of Lindsay : 

" When I was with Mr M'Intosh, I attended classes that 
were taught by Mr Lindsay, a man of profound learning 
and untiring scientific research, who, had he been more 
practical, less diffident, and possessed of greater worldly 
wisdom, would have gained for himself a good place 


amongst distinguished men. As it was, he remained 
little more than a mere abstraction, a cyclopaedia out of 
order, and went through life a poor and modest school- 

" By the time I knew him he was devoting much of his 
attention to electricity, to the celerity with which it was 
transmitted to any distance, and to the readiness with 
which its alternating effects may be translated into speech 
and I have no doubt he held in his hand the modern 
system of the telegraph, but it needed a wiser man than 
he to turn it to practical use. He also produced from gal- 
vanic cells a light which burned steadily for a lengthened 

" His acquaintance with languages was extraordinary, 
and almost equalled that of his famous contemporary, the 
Cardinal Mezzofanti. In 1828 he began the compilation of 
a dictionary in fifty languages, the object of which was to 
discover, if possible, by language the place where, and the 
time when, man originated. This stupendous undertaking, 
which occupied the main part of his life's work, he left 
behind in a vast mass of undigested manuscript, consist- 
ing of dissertations on language and cogitations on social 
science a monument of unpractical and inconclusive in- 
dustry. In 1845 he published *A Pantecontaglossal 
Paternoster,' intended to serve as a specimen of his fifty- 
tongued lexicon. 

"In 1858 he published 'The Chrono - Astrolabe,' for 
determining with certainty ancient chronology a work on 
which he had been engaged for many years; and in 1861 
; A Treatise on Baptism,' which is a curious record of his 
philosophical knowledge. . . . 

"In 1832 he obtained a situation as travelling tutor, 
which was to take him abroad for some time. We loved 
him as much as consists with a boy's nature to love his 


teacher, and subscribed for a silver snuff-box as a slight 
mark of our regard. 1 . . . 

" I am afraid that the situation of travelling tutor did 
not turn out well, for within two years Lindsay was back 
again in Dundee, and resumed his position of assistant 
teacher, arduously following at the same time his favourite 
studies." 2 

The scope of his teaching at this time is shown by the 
following notice which appeared in the ' Dundee Advertiser ' 
of April 11, 1834: 

" J. B. Lindsay resumes classes for cultivating the intel- 
lectual and historical portions of knowledge and instruction 
on April 14, 1834, in South Tay Street, Dundee. 

" In a few weeks hence a course of lectures will be formed 
on frictional, galvanic, and voltaic electricity ; magnetism ; 
and electro-magnetism. The battery, already powerful, is 
undergoing daily augmentation. The light obtained from 
it is intensely bright, and the number of lights may be 
increased without limit. 

"A great number of wheels may be turned [by electricity], 
and small weights raised over pulleys. 

"Houses and towns will in a short time be lighted by 
electricity instead of gas, and heated by it instead of coal ; 
and machinery will be worked by it instead of steam all 
at a trifling expense. 

" A miniature view of all these effects will be exhibited, 
besides a number of subordinate experiments, including the 
discoveries of Sir Humphry Davy." 

In March 1841, Lindsay was appointed teacher in the 

1 On a previous occasion (July 1829) he was presented with a new 
hat (!) by the pupils "for the attention he had bestowed in facili- 
tating their studies." 

2 Alex. Maxwell's (unpublished) Autobiographical Notes and 


Dundee Prison on a salary of 50 a-year, a post which he 
held for upwards of seventeen years, till October 1858. 
It is stated that shortly after taking up this office he could 
have obtained an appointment in the British Museum, a 
situation which would have been most congenial to his 
tastes, and which would certainly have led to a lasting 
recognition of his great abilities ; but, being unwilling to 
leave his aged mother, he declined the offer a rare example 
of devotion and self-denial. . . . 

Lindsay was a bachelor, and lived alone, buried, it might 
be said, in his books, collections of which, in history and 
philosophy, science and languages, were heaped in every 
corner of his dwelling a small house of three apartments 
(11 South Union Street). The kitchen was filled with 
electrical apparatus, mostly the work of his own hands ; and 
his little parlour was so crowded with books, philosophical 
apparatus, and other instruments of his labour, that it was 
difficult to move in it. To provide these things, he denied 
himself through life the ordinary comforts and conveniences, 
bread and coffee, and other simple articles, forming the 
principal part of his diet. His house in time acquired a 
celebrity as one of the curiosities of Dundee, and men of 
learning from distant parts, not only of the kingdom but of 
the world, often came to pay him a visit. 

In July 1858, on the recommendation of Lord Derby, 
then Prime Minister, her Majesty granted Lindsay an 
annual pension of 100 a-year, "in recognition of his 
great learning and extraordinary attainments." This well- 
deserved bounty relieved him from the drudgery of a prison 
teacher, and henceforth to the close of his life he devoted 
himself entirely to literary and scientific pursuits. 

Although never robust, Lindsay on the whole enjoyed 
tolerably good health through life, but trouble came at last. 



On June 24, 1862, he was seized with diarrhoea, which 
carried him off on June 29, 1862, in the sixty -third year of 
his age. 1 

Although languages and chronology took up much (I am 
inclined to think too much) of Lindsay's time, still electricity 
and its applications were his first, as they were always his 
favourite, study. Amongst some notes and memoranda, 
bound up with his manuscripts in the Albert Institute, 
Dundee, he says : 

"Previous to the discovery of Oersted, I had made many 
experiments on magnetism, with the view of obtaining from 
it a motive power. No sooner, however, was I aware of the 
deflection of the needle and the multiplication of the power 
by coils of wire than the possibility of power appeared 
certain, and I commenced a series of experiments in 1832. 
The power on a small scale was easily obtained, and during 
these experiments I had a clear view of the application of 
electricity to telegraphic communication. The light also 
drew my attention, and I was in a trilemma whether to fix 
upon the power, the light, or the telegraph. After reflection 
I fixed upon the light as the first investigation, and had 
many contrivances for augmenting it and rendering it 
constant. Several years were spent in experiments, and I 
obtained a constant stream of light on July 25, 1835. 
Having satisfied myself on this subject, I returned to some 
glossological investigations that had been left unfinished, 
and was engaged with these till 1843. In that year I pro- 
proposed a submarine telegraph across the Atlantic, after 
having proved the possibility by a series of experiments. 
Inquiries on other subjects have since that time engaged 
my attention, but I eagerly desire to return, to electricity." 

The first public announcement of Lindsay's success in 

1 Norrie's Dundee Celebrities of the Nineteenth Century, Dundee, 


electric lighting was contained in a short paragraph in the 
'Dundee Advertiser' of July 31, 1835 ; and on October 30 
following the same paper published a letter on the subject 
from Lindsay himself : 


" SIR, As a notice of my electric light has been exten- 
sively circulated, some persons may be anxious to know its 
present state, and my views respecting it. 

" The apparatus that I have at present is merely a small 
model. It has already cost a great deal of labour, and will 
yet cost a good deal more before my room is sufficiently 
lighted. Had circumstances permitted, it would have been 
perfected two years ago, as my plans were formed then. I 
am writing this letter by means of it, at 6 inches or 8 inches 
distant ; and, at the present moment, can read a book at 
the distance of 1 J foot. From the same apparatus I can get 
two or three lights, each of which is fit for reading with. I 
can make it burn in the open air, or in a glass tube without 
air, and neither wind nor water is capable of extinguishing 
it. It does not inflame paper nor any other combustible. 
These are facts. 

" As I intend in a short time to give a lecture on the 
subject, my views on the further progress will be unfolded 
then. A few of these, however, may be mentioned just 

" Brilliant illumination will be obtained by a light incap- 
able of combustion ; and, on its introduction to spinning 
mills, conflagrations there will be unheard of. Its beauty 
will recommend it to the fashionable ; and the producing 
apparatus, framed, may stand side by side with the piano in 
the drawing-room. Requiring no air for combustion, and 
emitting no offensive smell, it will not deteriorate the 


atmosphere in the thronged hall. Exposed to the open 
day, it will blaze with undiminished lustre amidst tempests 
of wind and rain ; and, being capable of surpassing all lights 
in splendour, it will be used in lighthouses and for telegraphs. 
The present generation may yet have it burning in their 
houses and enlightening their streets. Nor are these pre- 
dictions the offshoots of an exuberant fancy or disordered 
imagination. They are the anticipated results of laborious 
research and of countless experiments. Electricity, moreover, 
is destined for mightier feats than even universal illumina- 
tion. J. B. LINDSAY. 

"DUNDEE, Oct. 28, 1835." 

Lindsay's connection with electric telegraphy forms a 
very interesting episode. We have seen that from about 
the year 1830 he was familiar with telegraphic projects, 
and that he made them the subject of illustration in his 
classes. At this date electric telegraphs were distinctly 
in the air, but, like electric lighting, they had hardly 
advanced beyond the laboratory stage. 1 Lindsay does 
not appear to have carried them much further for several 
years, for it was not until 1843 that he conceived the bold 
idea of a submarine telegraph to America by means of a 
naked wire and earth-batteries, "after having proved the 
possibility by a series of experiments." 

It is true that at this time the earth-battery was known. 
It was first proposed by Kemp, of Edinburgh, in 1828; 
Prof. Gauss in 1838 suggested its employment for tele- 
graphic purposes, and Steinheil, acting on the suggestion, 
actually used it with some success on the Munich-Nanhofen 

1 From the public exhibition of Baron Schilling's needle instru- 
ment in Germany in 1835-36 dates the first real start of electric 
telegraphy. See my 'History of Electric Telegraphy to 1837,' 
chap. ix. 


Railway, twenty-two miles long ; and Bain in October 1842 
employed it for Avorking clocks. Similarly, the idea of 
signalling with uninsulated wire and without any wire at 
all was not new, for, as we have seen, the possibility of 
doing so was in a manner forced on the notice of Steinheil 
in 1838 and on Morse in 1842, but Lindsay was certainly 
the first to combine the two principles in his daring pro- 
posal of an Atlantic telegraph ; and this, be it remembered, 
at a time when electric telegraphy was still a young and 
struggling industry, and when submarine telegraphy was 
yet a dream. 

On June 19, 1845, a short paragraph appeared in the 
'Northern Warder,' Dundee, referring to a New York 
project of communicating between England and America 
by means of a submerged copper wire "properly covered 
and of sufficient size." This called forth the following 
letter from Lindsay, which was published in the same 
paper on June 26 following : 


" SIR, The few lines I now send you have been occa- 
sioned by a notice in your last in reference to an electric 
telegraph to America. Should the plan be carried into 
effect the following hints should be attended to : The wire 
should be of pure copper, as otherwise it would be injured 
by the electro-chemical action of the water. The wire 
must not be composed of parts joined by soldering, but 
welded together ; this welding can be performed by elec- 
tricity. In order to prevent the action of water on the 
wire, a button of a more oxidable metal should be welded 
to it at short distances; the best metal for this purpose 
would be lead. If soldered to the wire, it must be soldered 
by lead alone. No third metal must be used. If welded, 


it may be done by electricity. In this way the wire resting 
on the bottom of the sea might last a long time. The one 
end of the wire is then to be soldered or welded to a plate 
of zinc immersed in the ocean on the coast of Britain, and 
the other end similarly joined to a plate of copper deposited 
in the same ocean on the coast of America. In reference 
to the expense, suppose the wire to be a ninth or tenth of 
an inch diameter, then the length of 100 inches would con- 
tain a cubic inch of copper, and three miles of wire would 
contain a cubic foot, weighing 9000 ounces, of the value 
of about 36 sterling. Owing to the inequalities in the 
bottom of the ocean, the distance to America might be 
3000 miles, and the expense 36,000 sterling a trifle 
when compared with the resulting benefit. The only 
injury that the wire is likely to undergo is from sub- 
marine eruptions. It may be broken by these. The two 
ends, however, being accessible, the greater part of the 
wire may be drawn up, and the necessary length of wire 
welded to it. It should be remembered that this welding 
must be done by electricity. To Calcutta, by the Cape of 
Good Hope, the expense would be 200,000. The wire 
from Calcutta to Canton would cost 70,000, to New 
Zealand 120,000, to Tahiti nearly 200,000. A wire 
might be placed round the coast of Britain, and another 
along the coast of America. There might be stations at 
different towns and electric clocks agreeing with each other 
to a second of time. Each town might have a specific time 
for intelligence. Suppose Dundee to have the hour from 
nine to ten. From nine to ten minutes past nine, mes- 
sages are sent and answers received between Dundee and 
New York. From ten minutes to twenty minutes past 
nine communication is made between Dundee and Quebec. 
The rest of the hour is for intercourse between Dundee 
and other towns. The same is done with Edinburgh, 


Glasgow, Liverpool, &c., each town having an hour for 
itself. L. 

"DUNDEE, June 21, 1845. "^ 

From this letter it is clear that Lindsay then contem- 
plated an uninsulated wire across the Atlantic in connection 
with what have come to be known as earth -batteries at 
the stations along the coasts. His plan of protecting the 
wire from the corrosive action of the sea-water was evidently 
borrowed from Sir Humphry Davy's proposal of 1824 for 
the protection of the copper sheathing of ships by strips of 
zinc ; while the further suggestion, on which he insists so 
much, of welding the various lengths of wire by electricity, 
if not original with him, was at all events a very early 
recognition of a process which has cropped up again in 
recent years, and which is now largely employed. 1 

Between 1845 and 1853 Lindsay does not appear to have 
done anything in furtherance of his Atlantic project, being 
probably wholly absorbed in his linguistic and chronological 
studies. At all events, we hear nothing from him until 
March 11, 1853, when a notice appeared in the 'Dundee 
Advertiser ' of a lecture which he proposed to give on the 
ensuing Tuesday at the Thistle Hall. 

In the same paper a week later a report of the lecture is 
given as follows : 


" On Tuesday evening our learned and ingenious towns- 
man, Mr J. B. Lindsay, delivered a lecture on the above 
subject, one with which he has an acquaintance second to 

1 Electric welding was proposed by Joule in 1856 ; by Wilde in 
1865 ; and by Prof. Elihu Thomson (America) and Dr Benardos 

(Russia) in 1887. 


no man in the kingdom. It would be impossible, in the 
limited space at our disposal, to give any vidimus of the 
lecture j we can only indicate the outline of a recent dis- 
covery made by Mr Lindsay, involving a principle which, if 
capable of acting irrespective of distance (and we see no 
reason to doubt that it is), must by-and-by revolutionise 
all our ideas of time and space. Mr Lindsay stated the 
principle to be that submerged wires, such as those now 
used for telegraphic intelligence between this country and 
Ireland and France, were no longer necessary. By a 
peculiar arrangement of the wires at the sides of rivers or 
seas, the electric influence can be made to pass on through 
the water itself. This proposition was certainly startling, 
but he illustrated it on a small scale by means of a water- 
trough, and, so far as the experiment went, it faithfully 
developed the principle. Mr Lindsay, after concluding 
these experiments, proceeded to point out the lines which 
appeared to him most eligible for transmitting telegraphic 
intelligence throughout the world ; and, having done so, he 
wound up with a peroration of great beauty, in which the 
wonders to be achieved by electric influence in the days to 
come were eloquently set forth. It is a fine sight to see 
this learned and philosophic man pursuing the studies of 
science and literature, not for the sake of any empty 
applause, but for those pure pleasures they are in themselves 
so well fitted to bestow. At the same time it is gratifying 
to know that there are many people capable of appreciating 
the modest and retiring character of Mr Lindsay, a fact 
which was clearly evidenced on Tuesday evening by the 
numerous and most respectable meeting which then 
assembled to hear his scientific lecture." 

In the following August Lindsay delivered another 
lecture (probably the same) in Glasgow, and so sanguine 


was lie at this time of the practicability of his method that 
he actually patented it on June 5, 1854. The following 
account, which I have condensed from the specification of 
his patent, explains the modus operandi, and also shows 
how well he understood the conditions of the problem : 

" My invention consists of a mode of transmitting tele- 
graphic messages by means of electricity or magnetism 
through and across water without submerged wires, the 
water being made available as the connecting and conduct- 
ing medium by the following means : 

"On the land, on the side from which the message is to 
be sent, I place a battery and telegraph instrument, to 
which are attached two wires terminating in metal balls, 
tubes, or plates placed in the water or in moist ground 
adjacent to the water at a certain distance apart, according 
to the width of the water to be crossed (the distance 
between the two balls, plates, or tubes to be greater than 
across the water when practicable). On the land which is 
situated on the opposite side of the water, and to which 
the message is to be conveyed, I place two similar metal 
balls, plates, or tubes, immersed as above stated, and 
having wires attached to them which lead to, and are in 
connection with, another battery and needle indicator, or 
other suitable telegraphic instrument. A, A in the diagram 
(fig. 2) show the position of the battery and instru- 
ment on one side of the water, z ; B, B, the battery and 
instrument on the opposite side ; c, D, E, F, metallic or 
charcoal terminators; G, H, i, K, wires insulated in the usual 
way, and connecting the terminators, batteries, and instru- 
ments, as shown. 

"As regards the power or primary agent, it may be 
either voltaic, galvanic, or magnetic electricity, and the 
apparatus for evolving the same, such as is used for ordi- 
nary telegraphic purposes. 



"As regards the indicating apparatus, I propose to 
employ any of the instruments in known use which are 
most efficient for my purpose, observing that the needle 
indicator may be arranged either in a vertical or in a hori- 
zontal position, and that the coil of wire which actuates 



the needle may be increased or diminished according to 

" Suppose it is required to transmit a message from A, 
the operator completes the circuit of the electric current as 
ordinarily practised. 1 It will be evident that the current 

1 That is, by a key, which is not shown in the diagram. The 
absence of keys, no doubt, led a writer to say that Lindsay's method 
consisted ' ' in providing strong enough batteries, one to send the 
current half the distance and the other to attract it the other half " ! 


will have two courses open to it, the one being directly 
back through the water from c to D, and the other across the 
water from c to E, along the wires I K, through the instru- 
ment B, and back from F to D. Kow, I have found that if 
each of the two distances c D and E F be greater than c E 
and D F, the resistances through c E and D F will be so 
much less than that through the water between c and D, 
that more of the current will pass across the water, through 
the opposite wires, and recross at F, than take the direct course 
CD; or, more correctly speaking, the current will divide 
itself between the two courses in inverse ratio to their 
resistances. As cases may arise, from local or other causes, 
such as not to admit of the distance between the immersed 
plates being greater than the distance across the water, 
I propose, then, to augment the force of the batteries, 
and to increase the size of the plates, so as to compel a 
sufficient portion of the current to cross. I prefer, how- 
ever, when circumstances admit of it, employing the first 

Lindsay's first public trials were across the Earl Grey 
Docks at Dundee, and then across the Tay at Glencarse, 
where the river is nearly three-quarters of a mile wide. 
Of the few friends who assisted at these experiments 
Mr London of Dundee is, I believe, the only one now 
left. He tells us that Lindsay would station them on 
one side of the Tay, enjoining them to watch the gal- 
vanometer and note down how the needle moved. He 
would then insert his plates in the water on their side 
of the river, and, crossing over to the opposite side, 
would complete his arrangements. With a battery of 
twenty-four Bunsen cells he would make a few momen- 
tary contacts, reversing the connections a few times so 
as to produce right and left deflections of the galvano- 
meter needle. Then he would return and compare the 


deflections of the needle which they had noted with 
the order in which he had himself made the battery 
contacts, and on finding them to correspond he would 
be supremely happy. 1 

In 1854 Lindsay was in London, and brought his plans 
to the notice of the Electric Telegraph Company. It is 
now curious to remark that Mr "W. H. Preece, who, as 
we shall see later on, became himself in after years an 
eminent wireless -telegraph inventor, was the officer who 
was deputed to assist him and report on his method. Mr 
Preece tells us that these were almost the first electrical 
experiments of any importance in which he ever took part, 
and in a letter to the writer, dated October 15, 1898, he 
adds : "I remember Lindsay very well. He came up 
to London with his 'great invention,' and I assisted him 
in making his experiments in our gutta-percha testing tank 
at Percy Wharf on the Thames. We used the old sand 
battery and galvanometers ohms and volts were not in- 
vented then and showed that by varying the distance 
apart of the plates on each side of the tank we varied 
the strength of the signals. I have no record of the 
results, but they showed the feasibility of the plan. I 
had, however, to crush poor Lindsay by telling him that it 
was not new. Morse in 1842 had done the same thing, 
and Alexander Bain had also tried about the same time 
a similar experiment on the Serpentine, but I have not 
found any published record of it." 2 

In August 1854 Lindsay carried out a series of experi- 
ments at Portsmouth, in w r hich, according to a notice in 
the 'Morning Post' (August 28), he completely succeeded 

1 Kerr, Wireless Telegraphy, 1898, p. 40. 

2 In this, I think Mr Preece's memory betrays him. Bain's ex- 
periments had to do with an insulated wire in connection with earth- 
batteries. See 'The Artisan,' June 30, 1843, p. 147. 


in transmitting signals across the mill dam, where it is 
about 500 yards wide. 1 

Lindsay repeated these experiments at intervals and at 
various places, indeed whenever and wherever he had the 
chance, his greatest performance being across the Tay, from 
Dundee to Woodhaven, where the river is nearly two miles 
broad. On one of these occasions, and when an Atlantic 
telegraph began to be seriously debated, the difficulty of 
finding a steamer large enough to carry the cable was 
discussed, when Lindsay quietly remarked, "If it were 
possible to provide stations at not more than twenty miles 
distant all the way across the Atlantic, I would save them 
the trouble of laying any cable." 

In September 1859 Lindsay read a paper before the 
British Association at Aberdeen " On Telegraphing without 
Wires," which drew from Lord Eosse, the president of the 
section, special commendation. Prof. Faraday and (Sir) 
G. B. Airy, then Astronomer - Royal, also added their 
approval of the views enunciated. Prof. Thomson (now 
Lord Kelvin) was also present, and, as is well known, 
was then deeply engaged with Atlantic cable projects. 
History does not say what he thought of the poor Dundee 

1 These experiments were also noticed in ' Charabers's Journal ' for 
September 1854, as follows: "Again has an attempt been made to 
send a signal through water without a wire this time at Ports- 
mouth, where it was attended with partial success. The thing has 
often been tried : a few years ago, a couple of savants might have 
been seen sending their messages across those minor lakes known to 
Londoners as the Hampstead Ponds ! " Can any reader tell me who 
these savants were ? 

About this time experiments in wireless telegraphy were evidently 
popular. Van Reese at Portsmouth ; Gintl, the first inventor of a 
duplex telegraph, in Austria ; Bouelli in Italy, and Bouchotte and 
Douat in France (and doubtless others), all were engaged on the 
problem, but with what results I do not know, as I have not met 
with any detailed accounts of their experiments. 


lecturer, but, with the experience of forty years, we can 
easily guess. 

A brief abstract of the paper was published in the 
Annual Eeport of the Association for 1859, but a fuller 
account appeared in the ' Dundee Advertiser,' from which 
I take the following interesting details : 

" The author has been engaged in experimenting on the 
subject, and in lecturing on it in Dundee, Glasgow, and 
other places since 1831. Eecently he had made addi- 
tional experiments, and succeeded in crossing the Tay 
where it was three-quarters of a mile broad. His method 
had always been to immerse two plates or sheets of metal 
on the one side, and connect them by a wire passing 
through > a coil to move a needle, and to have on the 
other side two sheets similarly connected, and nearly 
opposite the two former. Experiments had shown that 
only a fractional part of the electricity generated goes 
across, and that the quantity that thus goes across can 
be increased in four ways : (1) by an increased battery 
power; (2) by increasing the surface of the immersed 
sheets ; (3) by increasing the coil that moves the receiving 
needle ; and (4) by increasing the lateral distance of the 
sheets. In cases where lateral distance could be got he 
recommended increasing it, as then a smaller battery power 
would suffice. In telegraphing by this method to Ireland 
or France abundance of lateral distance could be got, but 
for America the lateral distance in Britain was much less 
than the distance across. In the greater part of his experi- 
ments the distance at the sides had been double the dis- 
tance across ; but in those on the Tay the lateral distance 
was the smaller, being only half a mile, while the distance 
across was three-quarters of a mile. 

" Of the four elements above mentioned, he thought 
that if any one were doubled the portion of electricity 


that crossed would also be doubled, and if all the elements 
were doubled the quantity transmitted would be eight 
times as great. In the experiments across the Tay the 
battery was of 4 square feet of zinc, the immersed sheets 
contained about 90 square feet of metal, the weight of the 
copper coil was about 6 lb., and the lateral distance was, 
as just stated, less than the transverse ; but if it had been 
a mile, and the distance across also a mile, the signals 
would, no doubt, have been equally distinct. Should this 
law (when the lateral distance is equal to the transverse) 
be found correct, the following table might then be 
formed : 

Zinc for battery. Immersed sheets. Weight of coil. Distance crossed, 

sq. ft. sq. ft. lb. miles. 

4 90 6 1 

8 180 12 8 

16 360 24 64 

32 720 48 512 

64 1440 96 4096 

128 2880 192 l 32,768 

" But supposing the lateral distance to be only half the 
transverse, then the space crossed might be 16,000 miles; 
and if it was only a fourth, then there would be 8000 
miles a much greater distance than the breadth of the 
Atlantic. Further experiments were, however, necessary 

1 My readers will smile at the suggestion of such galvanometer 
coils, but they should remember that forty years ago matters electri- 
cal were largely ordered by the rule of thumb. The electro-magnet 
first used by Morse on the Washington-Baltimore line (1844), and 
exhibited in Europe, weighed 185 lb. The arms were 3^ inches 
long and 18 inches diameter, the wire (copper) .being that known as 
No. 16 the same size as the line wire, it being then supposed that 
the wire of the coils and of the line should be of the same size 
throughout. Down to 1860 not a few practical telegraphists held 
this view. See D. G. FitzGerald in the London ' Electrical Keview,' 
August 9, 1895, p. 157, 


to determine this law, but, according to his calculations, 
he thought that a battery of 130 square feet, immersed 
sheets of 3000 square feet, and a coil of 200 lb., would 
be sufficient to cross the Atlantic with the lateral distance 
that could be obtained in Great Britain." 

After the reading of the paper Lindsay carried out some 
very successful experiments across the river Dee, in the 
presence of Lord Rosse, Prof. Jacobi of St Petersburg, and 
other members of the Association. In February 1860 he 
made Liverpool the scene of his operations, but there, 
strange to say, he had not the success which hitherto 
attended him. The experiments failed, being "counter- 
acted by some unaccountable influence which he had not 
before met with." However, in the following July he 
was again successful at Dundee in his experiments across 
the Tay, below the Earn, where the river is more than 
a mile wide. In communicating these results to the 
'Dundee Advertiser' (July 10, 1860), he says: "The 
experiment was successful, and the needle was strongly 
moved ; but as I had no person with me capable of sending 
or reading a message, it [regular telegraphic signalling] was 
not attempted." 

This was Lindsay's last public connection with the tele- 
graph, but to the end of his life (June 29, 1862) he re- 
mained perfectly convinced of the soundness of his views 
and of their ultimate success. 

J. W. WILKINS 1845. 

In the New York 'Electrical Engineer' of May 29, 1895, 
it was claimed for Prof. Trowbridge (of whom we shall 
have more to say later on) that he was the first to telegraph 
without wires in 1880, 

J. W. WILKINS. 33 

The paragraph in which this claim, unfounded as we 
already see, was advanced, besides drawing renewed atten- 
tion to Prof. Trowbridge's experiments, had the merit of 
calling forth an interesting communication from our own 
Mr J. "W. Wilkins, one of the very few telegraph officers of 
Cooke & Wheatstone's days still with us, and whose early 
and interesting reminiscences I hope we may yet see. 1 

Writing in 'The Electrician/ July 19, 1895, Mr Wilkins 
says : 

"Nearly fifty years ago, and thirty years before Prof. 
Trowbridge ' made original researches between the Observa- 
tory at Cambridge and the City of Boston,' the writer of 
these lines had also researched on the same subject, and a 
year or two later published the results of his investigations 
in an English periodical the ' Mining Journal ' of March 
31, 1849 under the heading 'Telegraph communication 
between England and France.' In that letter, after going 
into the subject very much like the American Professor in 
1880, there will be found my explanation also not differing 
much from the Professor's as to how the thing was to be 
done ; except that, in my case, I proposed a new and delicate 
form of galvanometer or telegraph instrument for the pur- 
pose, while he made use of the well-known telephone. I 
suggested the erection of lengths of telegraph wires on the 
English and French coasts, with terminals dipping into the 
earth or sea, and as near parallel as possible to one another ; 
and I suggested a form of telegraph consisting of ' coils of 
finest wire, of best conductibility,' with magnets to deflect 
them, on the passage of a current of electricity through them, 
which I expected would take place on the discharge of elec- 
tricity through the circuits on either side of the water; 

1 Mr Wilkins is the author of two English patents : (1) Improve- 
ments in Electric Telegraphs, January 13, 1853 ; and (2) Improve- 
ments in obtaining power by Electro-Magnetism, October 28, 1853. 



anticipating, of course, that a portion of the current would 
flow from the one pair of earth-plates terminals of one 
circuit to the other pair of terminals on the opposite shore. 

" It may be interesting to relate how I came to think 
that telegraphy without wires was a possibility, and that it 
should have appeared to me to have some value, at a time 
when gutta-percha as an insulator was not imagined, 
or the ghost of a proposition for a submarine wire 
existed. At that time, too, it was with the utmost diffi- 
culty that efficient insulation could be maintained in 
elevated wires if they happened to be subject to a damp 

"It was in the year 1845, and while engaged on the 
only long line of telegraph then existing in England 
London to Gosport that my observations led me to 
question the accepted theory that currents of electricity, 
discharged into the earth at each end of a line of telegraph, 
sped in a direct course instinctively, so to say through 
the intervening mass of ground to meet a current or find a 
corresponding earth-plate at the other end of it to complete 
the circuit. I could only bring myself to think that the 
earth acted as a reservoir or condenser in fact, receiving 
and distributing electricity almost superficially for some 
certain or uncertain distance around the terminal earths, 
and that according to circumstances only. A year later, 
while occupied with the installation of telegraphs for 
Messrs Cooke & Wheatstone (afterwards the Electric Tele- 
graph Company), a good opportunity offered of testing this 
matter practically upon lengths of wire erected on both 
sides of a railway. To succeed in my experiment, and 
detect the very small amount of electricity likely to be 
available in such a case, I evidently required the aid of a 
very sensitive galvanometer, much more so indeed than the 

J. W. WILKINS. 35 

long pair of astatic needles and coil of the Cooke & Wheat- 
stone telegraph, which was then in universal use as a 
detector. The influence of magnetism upon a wire con- 
veying an electric current at once suggested itself to me, 
and I constructed a most sensitive instrument on this 
principle, by which I succeeded in obtaining actual signals 
between lengths of elevated wires about 120 ft. apart. 
This, however, suggested nothing more at the moment than 
that the current discharged from the earth-plates of one 
line found its way into the earth-plates of another and 
adjacent circuit, through the earth. Later on, I had other 
opportunities of verifying this matter with greater distances 
between the lines of wire, and ultimately an instance in 
which the wires were a considerable distance apart, and 
with no very near approach to parallelism in their situa- 
tion. Then it was that it entered my head that telegraph- 
ing without wires might be a possibility." 

The following extracts from the letter in the 'Mining 
Journal,' above referred to, may now be reproduced with 
interest. I have slightly altered the phraseology with a 
view of making the writer's meaning more clear and 
connected : l 

"Allow me, through the medium of your valuable 
journal, to draw attention to a principle upon which a 
telegraphic communication may be made between England 
and France without wires. I take for certain (as experi- 
ments I have made have shown me) that when the poles 
of a battery are connected with any extended conducting 
medium, the electricity diffuses itself in radial lines between 

1 Mr C. Bright has recently reprinted this letter verbatim in ' Jour. 
Inst. Elec. Engs.,' vol. xxvii. p. 958, as containing " the first really prac- 
tical suggestion in the direction of inductive telegraphy " ; but, as we 
now see, it is not the first suggestion, and it is certainly not inductive. 


the poles. The first and larger portion will pass in a 
straight line, as offering the least resistance ; the rays will 
then form a series of curves, growing larger and larger, 
until, by reason of increasing distance, the electricity 
following the outer curves is so infinitesimal as to be no 
longer perceptible. 

" These rays of electricity may be collected within a 
certain distance focussed as it were by the interposition 
of a metallic medium that shall offer less resistance than 
the water or earth ; and, obviously, the nearer the battery, 
the greater the possibility of collecting them. I do not 
apprehend the distance of twenty miles being at all too 
much to collect a sufficient quantity of electricity to be 
useful for telegraphic purposes. If, then, it is possible, as 
I believe, to collect in France some portion of the elec- 
tricity which has been discharged from a battery in 
England, all that is required is to know how to deal with 
it so that it shall indicate its presence. 

"The most delicate of the present telegraph apparatus, 
the detector, being entirely unsuited for the purpose, I pro- 
pose the following arrangement : Upon one shore I propose 
to have a battery that shall discharge its electricity into the 
earth or sea, with a distance between its poles of five, ten, 
or twenty miles, as the case may be. Let a similar length 
of wire be erected on the opposite coast, as near to, and 
parallel with, it as possible, with its ends also dipping into 
the earth or sea. In this circuit place an instrument con- 
sisting of ten, twenty, or more round or square coils of the 
finest wire of best conductibility, suspended on points or 
otherwise between, or in front of, the poles of an electro-, 
or permanent, magnet or magnets. Any current passing 
through the coil would be indicated by its moving or shift- 
ing its position with reference to the poles of the magnet. 
This would constitute a receiving apparatus of the most 

J. W. WILKINS. 37 

delicate character, for its efficiency would depend not so 
much on the strength of the current passing as on the 
power of the magnet, which may be increased at pleasure. 

" I hope some one will take up this suggestion and carry 
it out practically to a greater extent than my limited experi- 
ments have enabled me to do. Of its truth for long as well 
as for short distances I am satisfied, and only want of 
means and opportunity prevent me carrying it out myself." 

In a recent letter to the writer apropos of this early pro- 
posal, Mr Wilkins says : 

" I will just say that all thought of induction was absent 
in my first experiments. I modified my views in this 
respect a year or two later, but I did not attach sufficient 
importance to the matter to follow up my communication to 
the ' Mining Journal,' especially as at that time a cable was 
actually laid across the Channel, which I could not doubt 
would be a success, and a permanent one too. I rather 
courted forgetfulness of the proposition. Whatever my 
opinion at the time was as to the source of the electricity 
that I discovered in the far removed and disconnected 
circuit, the result was the same, and the means I used to 
obtain it the same in principle as those which make the 
matter an accomplished fact to-day viz., elevated lengths of 
wire, and the discharge of electricity from the one on to a 
delicate receiving apparatus in the circuit of the other. 

"As regards the form of receiving apparatus which I 
suggested for indicating the signals, I did then, and do now, 
attach great importance to the happy idea. It happens to 
be the most delicate form of detector or galvanometer, and 
is identical in principle with Lord Kelvin's apparatus for 
long cable working, which, in his Siphon Recorder Patent, 
he says is as sensitive as his Mirror Galvanometer." 

This principle, as the practical reader knows, has been 
largely used in telegraphy. Besides Lord Kelvin's appli- 


cation of it, we have the Brown and Allan Eelay, the 
Weston Kelay, and Voltmeter, and other contrivances of a 
similar nature; 1 but Mr Wilkins was himself the first to 
put it in practice, and under the following interesting cir- 
cumstances : In 1851 he went to America to assist Henry 
O'Reilly of New York, a well-known journalist, who had a 
concession from the patentees of the Morse system for the 
erection of telegraph lines, at a royalty per mile. Disputes 
soon arose, and the Morse Syndicate sought to prevent 
O'Reilly from using their relay, without which the Morse 
instruments would be useless for long distances. In this 
difficulty O'Reilly adopted Bain's electro-chemical apparatus, 
and employed it for a time on the People's Telegraph from 
New York to Boston, via Albany. But finding that it was 
impossible to use this instrument in connection with inter- 
mediate stations, O'Reilly was again in a difficulty, when Mr 
Wilkins came to the rescue by saying he could devise a 
relay which did not require an iron armature, or electro- 
magnet of the ordinary form, and which would therefore be 
independent of the Morse patent. Very soon relays con- 
sisting of movable coils of wire, suspended between the 
poles of a magnet, were constructed in the workshop of 
John Gavitt, a friend of O'Reilly's, and then famous as a 
bank-note engraver. The instruments were placed in the 
circuit of the People's Telegraph, and O'Reilly was saved 
but only for a time, as in the end he was beaten by his 
powerful opponents. The Wilkins relay was put aside and 
soon forgotten, but forty-three years later it was brought 
forward again by Mr Weston as an original invention. 2 

1 The germ of all these instruments, as well as the Axial Magnets 
of Prof. Page and Royal E. House, was sown by Edward Davy in 
England in 1837. See my 'History of Electric Telegraphy,' 1884, 
pp. 356, 357. 

2 See the New York ' Electrical Engineer,' February 21, 1894. 



One of the first difficulties encountered in the early days 
of the telegraph in India was the crossing of the great 
water-ways that abound in that country ; and it was this 
difficulty which first directed the attention of Dr O'Shaugh- 
nessy, the introducer of the system in India, to the subject 
of subaqueous telegraphy. 

In 1849 he laid a bare iron rod under the waters of the 
river Huldee, 4200 feet wide, with batteries and delicate 
needle instruments in connection on each bank. Signals 
were passed, but " it was found that the instruments 
required the attention of skilful operators, and that in 
practice such derangements occurred as caused very frequent 

He next tried the experiment without any metallic con- 
ductor, using the water alone as the sole vehicle of the 
electric impulses, but, though he again succeeded in passing 
intelligible signals, he found that the battery power for 
practical purposes would be enormous (he used up to 250 
cells of the nitric acid and platinum form), and therefore 
prohibitively expensive. 

Although for practical purposes he soon abandoned the 
idea of signalling across rivers with naked wires, and with- 
out any wires at all, O'Shaughnessy for many years took 
great interest in the subject. Thus as late as 1858 we find 
him performing some careful experiments in the lake at 
Ootacamund, and in his Administration Report of the Tele- 
graph Department for that year he says : " I have long since 
ascertained that two naked uncoated wires, kept a moderate 
distance say 50 or 100 yards apart, will transmit electric 
currents to considerable distances (two to three miles) suf- 
ficiently powerful for signalling with needle instruments." 


E. AND H. HIGHTON 1852-72. 

The brothers Edward and Henry Highton, who were 
well-known inventors in the early years of electric teleg- 
raphy, took up the problem of transaqueous communica- 
tion about 1852. In Edward Highton's excellent little book, 
* The Electric Telegraph : Its History and Progress/ pub- 
lished in that year, he says : " The author and his brother 
have tried many experiments on this subject. Naked 
wires have been sunk in canals, for the purpose of ascer- 
taining the mathematical law which governs the loss of 
power when no insulation was used. Communications 
were made with ease over a distance of about a quarter 
of a mile. The result, however, has been to prove that 
telegraphic communications could not be sent to any con- 
siderable distance without the employment of an insulated 

On the other hand, Henry Highton long continued to 
believe in its practicability, and made many further experi- 
ments to that end. These were embodied in a paper read 
before the Society of Arts on May 1, 1872 (Telegraphy 
without Insulation), from which I condense the following 
account : 

" I have for many years been convinced of the possibility 
of telegraphing for long distances without insulation, or 
with wires very imperfectly insulated ; but till lately I had 
not the leisure or opportunity of trying sufficient experi- 
ments bearing on the subject. I need hardly say that 
the idea has been pronounced on all hands to be entirely 
visionary and impossible, and I have been warned of the 
folly of incurring any outlay in a matter where every 
attempt had hitherto failed. But I was so thoroughly 


convinced of the soundness of my views, and of the 
certainty of being able to go a considerable distance with- 
out any insulation, and any distance with very imperfect 
insulation, that I commenced, some three or four months 
since, a systematic series of experiments with a view to 
test my ideas practically. 

" I began by trying various lengths of wire, dropped in 
the Thames from boats, and found that I could, without 
the slightest difficulty, exceed the limits allowed hitherto 
as practicable. This method, however, was attended with 
much difficulty and inconvenience, owing to the rapidity of 
the tides and the motion of the boats. I next tried wires 
across the Thames, but had them broken five or six times 
by the strength of the current and by barges dragging their 
anchors across them. 

"1 then put the instrument in my own room, on the 
banks of the river, and sent a boat down stream with a 
reel of wire and a battery to signal to me at different dis- 
tances. The success was so much beyond my expectations, 
that I next obtained leave to lay down wires in Wimbledon 
Lake. As the result of all these experiments I found that 
water is so perfect an insulator for electricity of low tension 
that wires charged with it retained the charge with the 
utmost obstinacy; and, whether from the effect of polar- 
isation (so-called), or, as I am inclined to suppose, from 
electrisation of the successive strata of water surrounding 
the wire, a long wire, brought to a state of low electrical 
tension, will retain that tension for minutes, or even hours. 
Xotwithstanding attempts to discharge the wire every five 
seconds, I have found that a copper surface of 10 or 12 
square feet in fresh water will retain a very appreciable 
charge for a quarter of an hour ; and even when we attempt 
to discharge it continuously through a resistance of about 


thirty units [ohms], it will retain an appreciable though 
gradually decreasing charge for five or six minutes. 1 

" Since that time I have constructed an artificial line, 
consisting of resistance coils, condensers, and plates of 
.copper in liquids, acting at once as faults and as condensers, 
so that I might learn as far as possible to what extent the 
principle of non- insulation can be carried, and I have 
satisfied myself that, though there are difficulties in very 
long lengths absolutely uninsulated, yet it is quite feasible 
to telegraph, even across the Atlantic, with an insulation of 
a single unit instead of the 170,000 units [absolute] of the 
present cables. 

" The instrument with which I propose to work is the 
gold-leaf instrument, constructed by me for telegraphic 
purposes twenty-six years ago, 2 acted upon by a powerful 
electro-magnet, and with its motions optically enlarged. 
The exclusive use of this instrument in England was 
purchased by the Electric and International Telegraph 
Company, but it was never practically used, except in 
Baden, where a Government commission recommended it 
as the best. One of its chief merits is its extreme light- 
ness and delicacy. Judging by the resistance it presents 
to the electric current, it would appear that the piece of 
gold-leaf in the instrument now before us does not weigh 
more than 2-oVo"th P ar t f a grain ; let us even say that it 
weighs four times more, or Tw tn P art 'f a grain. I n 
order, then, to make a visible signal we only have to move 
a very, very small fraction of a grain through a very, very 
small fraction of an inch. You may judge of its delicacy 

1 It does not appear to have struck our author that these effects 
would militate against the practical application of his method. 

2 A special arrangement of this instrument, adapting it for long 
and naked (or badly insulated) lines, was patented February 13, 
1873. For reports of its great delicacy see 'Telegraphic Journal,' 
February 15, 1874. 


when I show you that the warmth of the hand, or even a 
look, by means of the warmth of the face turned towards 
a thermopile, can transmit an appreciable signal through a 
resistance equal to that of the Atlantic cable (experiment 
performed). Another great merit of this instrument is its 
ready adaptability to the circumstances in which it may be 
placed, as it is easy to increase or diminish the length, or 
breadth, or tension of the gold-leaf. Thus, increase of 
length or diminution of breadth increases the resistance, 
but also increases the sensitiveness ; and again, par- 
taking as it does partly of the character of a pen- 
dulum and partly of a musical string, the rapidity of 
vibration is increased by giving it greater tension and 
greater shortness, though by doing so the sensitiveness is 
diminished ; so that you can adjust it to the peculiar cir- 
cumstances of any circuit. Again, you notice the deadness 
of the movements and the total absence of swing, which, 
whenever a needle is used, always more or less tends to 
confuse the signals. The greatest advantage of all is that 
we can increase the sensitiveness without increasing the re- 
sistance, simply by increasing the power of the electro-magnet 
" Having now explained the construction of the instru- 
ment, and pointed out its merits, I proceed to show by 
experiment how tenaciously a piece of copper in water will 
retain a state of electrical tension. Here is a tub of fresh 
water, with copper plates presenting to each other about 
14 square feet of surface. I charge these plates with a 
Daniell cell, and you see how they retain the charge ; in fact, 
they will go on gradually discharging for several minutes 
through the small resistance of the gold-leaf instrument. I 
now do the same with a tub of salt water, and the result 
is still the same, though less marked. In fact, these 
plates, with the water between, represent the two metallic 
surfaces of a Leyden jar, and the water retains the elec- 


tricity of this small tension with much more obstinacy than 
the glass of a Leyden jar does the electricity of a higher 
tension. 1 

" Indeed, it is a fact of the highest importance in teleg- 
raphy that when there is a fault, electricity of a high 
tension, say of twenty or thirty Daniell cells, will almost 
wholly escape by it, and leave nothing for the instrument ; 
whereas electricity of a small tension, as from a single cell 
of large surface, will pass through the instrument with very 
little loss of power. This is strikingly shown by the use 
of an ordinary tangent galvanometer. I cannot well show 
it to a large audience like the present, therefore I will 
only inform you that when I have taken two currents, 
each marking 30 on the galvanometer, the one of high 
tension from thirty Daniell cells, and the other of low 
tension from a single cell of small internal resistance, a 
fault equivalent to the exposure of a mile of No. 16 wire 
in sea-water will annihilate all appreciable effects on the 
galvanometer when using the current of high tension, 
whereas the current of low tension will still show as much 
as 20. You see, then, the importance of using currents 
of low tension from a battery of large surface, and how a 
faulty cable can be worked with such currents when it is 
absolutely useless with currents of high tension. 

" There are three ways of signalling without insulation : 
one, only feasible for short distances ; a second, which I 
think will be found the most practicable ; and a third, in 
the practical working of which for very long distances 
several difficulties (though by no means insuperable) pre- 
sent themselves. 

1 These experiments are not clearly described in the report from 
which we are quoting. If we understand them aright, they are 
rather electrolytic than Leydeu-jar effects. In any case, as the tubs 
were presumably fairly well insulated, they have no bearing ad rem. 



"To explain the first plan, we will take the case of a 
river, and in the water near one bank place the copper 
plates A B, and connect them with a wire, including the 
battery P. Near the opposite bank submerge similar plates, 
c D, connected by a wire, in the circuit of which is placed 
the galvanometer G. Between A and B the current will 
pass by every possible route, in quantities inversely pro- 
portional to their resistances ; parts will pass direct by A B ; 
and other portions by A, c, D, B, and by A, c, G, D, B. 
Now, if the plates be large, and A c and B D respectively 

Fig. 3. 

comparatively near to each other, an appreciable current 
will pass from A to c, through G, and back from D to B ; 
but if the plates be small, the battery power small, and 
the distance from A to B and from c to D comparatively 
short, no appreciable amount will pass through the galvan- 
ometer circuit. I do not hesitate to say that it is possible, 
by erecting a very thick line wire from the Hebrides to 
Cornwall, by the use of enormous plates at each extremity, 
and by an enormous amount of battery power i.e., as 
regards quantity to transmit a current which would be 
sensibly perceived in a similar line of very thick wire, with 


very large plates, on the other side of the Atlantic. But 
the trouble and expense would probably be much greater 
than that of laying a wire across the ocean. 

"The second is the simplest and most feasible plan 
namely, laying across the sea two wires kept from metallic 
contact with each other, and working with that portion of 
the current which prefers to pass through this metallic 
circuit instead of passing across the liquid conductor, using 
currents of low tension from batteries of large surface. 

"The third method is to lay a single wire imperfectly 
insulated, and to place at the opposite end beyond the 
instrument a very large earth-plate. Any electrical tension 
thrown on this wire transmits itself more or less to the 
opposite end, and will be shown on any instrument of 
small resistance and sufficient delicacy. There are certain 
difficulties in this way of working, such as the effects of 
earth-currents and currents of polarisation which keep the 
needle or gold-leaf permanently deflected from zero, neces- 
sitating special means of counteraction. I have no doubt, 
from my experiments, that these difficulties may be over- 
come ; but still I think the simplest and most feasible, and 
not more expensive, plan will be to work with two naked 
wires kept apart from metallic contact, using electricity of 
a very low tension." l 

Soon after this Mr Highton turned a complete volte 
face, and went back to wires perfectly insulated, but at a 

1 The following cutting from 'Once a- Week' (February 26, 1876) 
is given here in the hope that some American reader will kindly sup- 
ply details, if any are procurable : " The ' New York Tribune ' gives 
an account of what appears to be a very remarkable discovery in 
electrical science and telegraphy. It is claimed that a new kind of 
electricity has been obtained, differing from the old in several partic- 
ulars, and notably in not requiring for transmission that the conduct- 
ing wires shaU be insulated. The difference is scarcely greater in kind 
than between polarised and non-polarised light, or between ordinary 


ri'Uculously small cost! On April 20, 1873, "he sent the 
following letter to the ' Times ' : 


" SIR, Some months ago I read a paper to the Society 
of Arts on the possibility of telegraphing for great distances 
without insulation, for which they were good enough to 
vote me a medal. I now find, however, that by the dis- 
covery of a new insulating material perfect insulation can 
be provided at a ridiculously small cost. 

" I find by the addition of this material, which is simply 
tar chymically modified, nearly 200,000 per cent is added 
to the insulating power of a thin coating of gutta-percha, I 
hope the result will shortly be found in the great cheapening 
of telegraphy. Yours, &c., H. HIGHTON." 

The new material here referred to was a preparation of 
vegetable tar and oxide of lead, which almost instantly 
solidified on application. In some experiments at the 
Silvertown Works, it was found that No. 18 copper wire, 
covered with gutta-percha weighing only 21 Ib. to the mile, 
had its insulation increased nearly 200,000 per cent, 
representing an insulation per mile of nearly three billion 
ohms ! enough, as the inventor needlessly remarked, for 
any lengths possible on the surface of the earth. 1 

iron and that which has been so changed by contact with platinum 
that the strongest nitric acid fails to attack it. A genuine discovery 
of the sort would be of inestimable service in cheapening the tele- 
graph, cable rates would soon be permanently reduced, and the un- 
sightly poles that now disfigure our cities would quickly disappear. " 
1 For reports on this cable see 'Telegraphic Journal,' vol. ii. pp. 
104, 129. 


G. E. DERING 1853. 

The problem of wireless telegraphy was taken up about 
this time by Mr George Dering of Lockleys, Herts, who 
was, like his old Rugby tutor, Henry Highton, a prolific 
inventor of electrical and telegraphic appliances, patents for 
which he took out on eleven separate occasions between 
1850 and 1858, and many of which came into practical 
use in the early Fifties. His needle telegraph, patented 
December 27, 1850, was in use in the Bank of England 
early in 1852, connecting the governor's room with the 
offices of the chief accountant, chief cashier, secretary, 
engineer, and other officials. About the same time it 
was partially used on the Great Northern Railway, and 
exclusively so on the first Dover-Calais cable (1851), where 
it did excellent service, working direct between London 
and Paris for a long time (including the busy period of the 
Crimean war), until supplanted by the Morse recording 

In the same specification of 1850, Dering patented three 
methods of carrying off atmospheric electricity from the line- 
wires : (a) " Two roughened or grooved metallic surfaces 
separated by fine linen, one of which is included in the 
line-wire circuit, and the other is in connection with the 
earth." This was afterwards (in 1854) repatented by (Sir) 
William Siemens, and is now known as Siemens' Serrated- 
Plate Lightning-Guard, (b) " The attraction or repulsion 
occurring between dissimilarly or similarly electrified bodies 
respectively. Thus metal balls may be suspended from the 
line-wire by wires, which on separating under the influ- 
ence of the lightning-discharge make contact with plates 
connected with the earth ; or the separation may simply 
break connection between the line-wire and the instrument." 

G. E. BERING. 49 

(c) "Introducing a strip of metallic leaf into the circuit, this 
being fused by the passage of the atmospheric electricity." 
This very effective method has also been reintroduced in 
later years, and always as a novelty, by various telegraph 

Bering's telegraphic appliances made a goodly show at 
the Great Exhibition of 1851, side by side with Henley's 
colossal magnets, and received " honourable mention." 
They were again on view at the Paris International Exhi- 
bition of 1855, where they were awarded a medal for 
general excellence. 

Bering's proposals for a transmarine telegraph are con- 
tained in his patent specification of August 15, 1853, from 
P~vhich we condense the following account : 
" The present invention is applicable to submarine tele- 
graphs, and also to the means of communication by under- 
ground or over-ground wires. Heretofore, in constructing 
electric telegraphs where the whole circuit has been made 
of metal, and also where the conducting property of the 
earth has been employed as a part of the circuit, it has 
been usual, and it has been considered absolutely necessary, 
to cause the wires to be thoroughly insulated, the con- 
sequence of which has been that the expense of laying 
down electric circuits has been very great, particularly 
where the same have crossed the sea or other waters, where 
not only have the wires been insulated, but in order to 
protect the insulating matter from injury further great cost 
, has been caused by the use of wire rope, or other means of 

"Xow, I have discovered that a metallic circuit formed 

of wires, either wholly uninsulated or partially so, may be 

employed for an electric telegraph, provided that the two 

1 parts of the circuit are at such a distance apart that the 

1 electric current will not all pass direct from one wire to the 



other by the water or earth, but that a portion will follow 
the wire to the distant end. 

" To -carry out my invention, I cause two uninsulated or 
partially insulated wires to be placed in the water or in the 
earth, at a distance apart proportionate to the total length 
of the circuit, the said wires being insulated where they 
approach one another to communicate with the instruments, 
in order to prevent the current passing through the dimin- 
ished water or earth space between them. The batteries 
(or other suitable source of electricity) employed are to be 
constructed in the proportion of their parts in conformity 
with the well-known laws which regulate the transmission 
of electric currents through multiple circuits that is, they 
should possess the properties generally understood by the 
term quantity in a considerably greater degree than is usual 
for telegraphing through insulated wires, which may be 
effected (in the case of galvanic batteries) by using plates 
of larger dimensions, or by other alterations in the exciting 
liquids or plates. The proper distance at which to place 
the conductors from one another is also determined by the 
same laws, all of which will be readily understood by per- 
sons conversant with the principles of electrical science. In 
practice I find that from one -twentieth to one -tenth the 
length of the line-wires is a sufficient distance. 

" Another method of carrying out my invention consists 
in establishing circuits composed in part of the uninsulated 
or partially insulated conductors, and in part of the con- 
ducting property of the sea, across which the communication 
is to be made, or of the earth or the moisture contained 
therein in the case of land telegraphs. For this purpose 
the connections are effected at such a distance in a lateral 
direction that a sufficient portion of the current will pass 
across the water or earth space and enter the corresponding 
wire connection at the other extremity. The connecting 

G. E. BERING. 51 

wires at the termini must be effectually insulated as in the 
first method. 

" A third method consists in placing in the sea or earth 
two wires of dissimilar metal having the quality of generat- 
ing electricity by the action of the water or moisture with 
which they are in contact. If at one extremity the wires 
be attached respectively to the two ends of the coil of an 
electro -magnet or other telegraphic apparatus, it will be 
found that the instrument is acted on by the current 
generated by the wires. If now at the other extremity the 
wires be connected, a portion of the current will complete 
its circuit through this connection, instead of all passing 
through the electro-magnet, where consequently the effect 
will be diminished; and if means be adopted to indicate 
this greater or less power, signals may be indicated at one 
end by making and breaking contact at the other. If de- 
sirable, currents derived from galvanic batteries, or other 
source, may be employed as auxiliary to those generated in 
the outstretched wires. 

" In the different means of communication which I have 
described, if strong conductors are required, as in submarine 
lines, wire rope may be employed, either alone or attached 
to chains for greater strength and protection, or the con- 
ducting wires may be attached to hempen ropes, or envel- 
oped within them. The metal composing the wires may be 
iron or copper or any other suitable kind, and it may be 
coated with varnish, by which means the amount of exposed 
surface will be diminished, and the metal preserved from 

" I will now suppose the case of a line to be carried out 
upon the principle which I have described, say from Holy- 
head to Dublin, a distance of about sixty miles. It would 
be necessary, first, to select two points on each coast from 
three to six miles apart, and to connect these points on each 


coast by insulated wires. Next, the two northern points 
are to be connected by a submerged uninsulated conduc- 
tor, and the two southern points by a similar conductor, 
unless the water be employed as a substitute in the manner 
before described. Thus an oblong parallelogram of con- 
tinuous conductors is formed, having for its longer sides 
the uninsulated conductors, and for its shorter sides the 
insulated wires along the coasts. If now these latter wires 
be cut at any parts, and instruments and batteries be con- 
nected in circuit, signals may be transmitted by any of the 
means ordinarily employed with insulated wires. 

" Or, to take the case of a longer line, say from England 
to America, I should select two points, as the Land's End 
in Cornwall and the Giant's Causeway in Ireland or some 
suitable place on the west coast of Scotland, and corre- 
sponding points on the American shore. Next, I should 
unite the two points in each country by insulated wires, 
and, finally, submerge two uninsulated conductors across 
the Atlantic, or one if the water be employed to complete 
the circuit. Then by introducing, as before, suitable tele- 
graphic instruments and batteries the communication will 
be established. 

" From the foregoing description it will be seen that the 
cost of laying down electric telegraphs, whether submarine 
or otherwise, is, by this invention of employing distance 
between the conductors as a means of insulation, reduced 
to little more than the mere cost of the wires, together 
with that of an insulated wire at each end; while the 
numerous difficulties which attend the insulation of long 
lengths of wire are avoided, as also the chances of the 
communication being interrupted by accidents to the 

At the time of this patent, and for many years after, the 
difficulties just referred to were only too real. Many of 

G. E. BERING. 53 

the cables laid between 1850 and 1860 failed after a longer 
or shorter period, and chiefly through defective insulation. 
Hence, no doubt, the persistency with which telegraph 
engineers in the Fifties sought in telegraphy without in- 
sulation, and telegraphy without wires, other and more 
economical ways of solving the great problem of trans- 
marine communication. 

Bering's experiments were performed across the river 
Mimram at Lockleys, Herts, with bare parallel wires of 
No. 8 galvanised iron, laid at a distance apart of about 
30 feet, or one-tenth of the space to be traversed. With 
a small battery power of only two or three Smee cells the 
signals were easily readable. 

At one of these performances on August 12, 1853, the 
chairman and directors of The Electric Telegraph Com- 
pany of Ireland (one of several mushroom companies then 
started) were present, and so impressed were they with 
the results obtained that they there and then decided to 
adopt the system for their intended line between Port- 
patrick and Donaghadee. This is a fact not generally 
known in the history of early submarine telegraph enter- 
prises, and what is still less known, for there is no record 
of it, is that the project was actually attempted. In a 
recent letter, Mr Bering, who I am glad to say is still 
with us, has given me some interesting details of the 
attempt which I now publish, feeling sure that they will 
be new to the reader. 

On September 23, 1853, the necessary wire in bundles 
was shipped to Belfast, which, "for the sake of ultra 
economy," consisted of single Xo. 1 galvanised iron instead 
of twisted strand wire as Dering had recommended. On 
examination the wire proved to be so unreliable, with 
numerous weak and brittle places chiefly at the factory 
welds that Dering urged delay and the substitution of 


stranded wire. " Had we been wise," writes Mr Dering, 
"we should have abandoned the attempt with this un- 
suitable material, but it was resolved to go on and risk it 
testing the wire as far as might be beforehand and removing 
the weak parts. I, however, addressed a formal letter to the 
board of directors in London, stating that the wire was so 
unreliable I must decline all responsibility as to the laying 
it down, but that I would do the best I could." 

After carefully testing the various lengths, removing all 
weak parts and bad welds as far as they could be discovered, 
and jointing and tarring the whole into one long length, the 
wire was paid into the hold of the Albert. On November 
21 a start was made, a shore-end wire was laid from Milisle, 
carried out to sea, and buoyed. Next morning the Albert, 1 
piloted by H.M.S. Asp (Lieut. Aldridge), picked up the 
buoyed end, joined it to the wire on board, and paid out 
successfully for about 3J miles, when the wire broke at a 
factory weld, and the ship returned to Donaghadee " in a 
gale of wind." 

The next few days were occupied in some alterations to 
the paying-out machinery, found by experience to be de- 
sirable, and on the 26th another start was made. The 
wire on board was joined to the buoyed end at 4 miles 
from shore, and paying-out proceeded successfully as far as 
mid-channel (about 12 miles) when the wire broke, again 
at a factory weld, and the end was lost in 82 fathoms of 
water. The ship then returned to the buoy and tried to 
underrun the wire, but it soon broke again, and for the 
moment further attempts were abandoned. 

Previous to this two unsuccessful attempts had already 
been made to connect Great Britain and Ireland by cables 
made on the lines of the Dover-Calais cable of 1851, one, 

1 With Dr Hamel on board, the famous Russian scientist of Alpine 
celebrity, as the representative of his Government. 


undertaken by Messrs Newall & Co., between Holyhead 
and Howth, June 1, 1852, which failed three days after; 
and the other, a heavy six-wired cable, undertaken by the 
same firm, between Portpatrick and Donaghadee, October 9, 
1852, which broke in a gale after sixteen miles had been 
paid out. 

In June 1854 Messrs Newall recovered the whole of this 
sixteen miles of cable, and completed the laying to Port- 
patrick, thus rendering another attempt at a bare wire cable 
unnecessary, if, indeed, it was still thought desirable. 

Mr Bering's faith in the soundness of his views is still 
unshaken, for he goes on to say : " Instead of a single 
wire, as in 1853, I should now advocate the use of a bare 
strand of wires for each of the conductors. And I must 
add, considering the craving there is at present for Wireless 
Telegraphs, that it seems to me not altogether improbable 
that the less ambitious but (for, at all events, long dis- 
tances) far more feasible plan of using bare wires will yet 
have its innings." And who, in these days of electrical 
marvels, will dare to say him nay? I, for my part, will 
not, for I have seen more unlikely things come to pass. 
The dream of to-day, " idle and ridiculous " as it may seem, 
has been so often realised on the morrow, that the cautious 
historian of science must not look for finality in any of 
its applications. 1 


On March 27, 1862, Mr Haworth patented "An im- 
proved method of conveying electric signals without the 
intervention of any continuous artificial conductor," in 

1 For recent applications of the bare-wire principle, see Melhuish, 
p. 114, infra. 


reference to which a lecturer of the period said : l "I have 
not met one single gentleman connected with the science of 
telegraphy who could understand his process, or its proba- 
bility of success. I applied to him for some information, 
but he is unwilling to communicate any particulars until 
experiment has sufficiently demonstrated the practicability 
of his plans." 

In the discussion which followed, Mr Cromwell Varley, 
electrician of the old Electric and International Telegraph, 
and the old Atlantic Telegraph, Companies, said : " Being 
informed that Sir Fitzroy Kelly and the learned chairman 
(Mr Grove) had seen Haworth's system in operation, and 
that the latter gentleman was a believer in it, he had tried 
the experiment upon a very small scale in his own garden, 
with apparatus constructed according to the instructions of 
Mr Haworth. His two stations were only 8 yards apart, 
and, although he used a very sensitive reflecting galvano- 
meter, and twelve cells of Grove's nitric acid battery, he 
could not get any signals, although the experiments were 
varied in every conceivable way." 

Under these circumstances it will not be surprising if I, 
too, after a careful study of the specification, and with the 
light thrown upon it by a further patent of October 30, 
1863, have failed to understand the author's method. In- 
deed, I feel in much the same mental condition towards it 
as Tristram Shandy's connoisseurs, who, " by long friction, 
incumbition, and electrical assimilation, have the happiness, 
at length, to get all be-virtu'd, be-pictured, be-butterflied, 
and be-fuddled." However, I will do my best to translate 
the terrible phraseology of the letters patent into plain 
English ; and if after this my readers cannot divine the 
mode of action I will not blame them nor must they 
blame me ! My description of the apparatus is based on 
1 T. A. Masey, Society of Arts, January 28, 1863. 



the complete specification and drawings of the second patent, 
which were lodged in the Patent Office on April 30, 1864, 
and which must therefore be supposed to contain the in- 
ventor's last word on the subject. 

A, z (fig. 4) are copper and zinc plates respectively, 
curved as shown, and buried in the earth about 3 feet 
apart. The superficies varies according to distance and 
other circumstances : thus, for distances up to 75 miles 
plates 1 foot square suffice ; over 75 and up to 440 miles, 
plates 24 by 16 inches are required. G, F are copper 
cylinders, 24 by 4 inches, buried in earth, which is 
always moist. At a point distant about 3 feet from the 

Fig. 5. 

centres of A and z a wooden box 3 is buried, containing a 
coil of insulated copper wire, No. 1 6 gauge, wound upon a 
wooden reel. The ends of the coil are attached to binding 
screws shown on top of the box. B is a wooden box con- 
taining a wooden reel divided into three compartments, x, 
y, z (fig. 5). x is filled with fine covered-copper wire, the 
ends of which are brought together and secured on the out- 
side of the reel, y is filled with thicker covered-copper 
wire, wound in the same direction as x, and the ends are 
severally connected to binding-screws, shown on the out- 
side, z is half filled with insulated iron wire, wound in the 
same direction as x and y ; the ends are fastened together 



on the outside of the reel as with coil x. The compartment 
is then filled with more of the same iron wire, wound 
double, and in the reverse direction to the coil below it. 
These double wires are not twisted, nor bound together, nor 
allowed to cross one another, but are wound evenly in 
layers side by side ; and the ends of each coil are secured 
together on the outside of the reel as in the case of the 
lower coil, and adjacent thereto. Usually the wire of coil 
x is No. 32 gauge ; ?/, No. 16 ; andz, No. 20 ; but the sizes 

Fig. 6. 

and quantities required must vary according to distance and 
other circumstances. 

c is any suitable telegraph instrument of the needle 

D is a condenser of a kind which an electrical Dominie 
Sampson would call prodigious ! A wooden box divided 
lengthwise into two compartments well coated with shellac. 
In each compartment is placed a band of stout gold-foil 
both w r ell insulated, and connected at their ends to the 
binding-screws a, #, and 6, h, respectively (fig. 6). Each 
compartment is filled with sixty rectangular plates of gutta- 


percha, on which insulated copper wire, No. 32 gauge, is 
wound in one continuous length from the first plate to the 
last, and the ends are attached to the binding-screws a, g, 
and b, h, respectively. " I fix binding-screws c, d, e, f, k, 
and I in the positions shown, and connect them with the 
wire upon the plates in its passage through the box. I 
then pass from end to end of each compartment over the 
plates, and lying on them, but well insulated from them, 
another band of stout gold-foil, and connect each end of it 
with the screws a, g, and &, h, respectively." 

E is another wooden box, containing a reel similar to B, 
but divided into only two compartments, each of which is 
filled with two copper wires, one covered and the other 
uncovered, wound side by side, and all four of different 
gauges from No. 18 to 30. The ends of one of the covered 
coils are brought to the screws p, p, shown on top of 
the box ; the ends of the other covered coil are fastened 
on the outside of the reel ; and the ends of the two 
uncovered coils are likewise fastened on the outside 
of the reel, "but in such a position that they can 
never come in contact with any uncovered part of the 
coated wire. Between each of the layers of wire I place a 
strip of non-metallic paper to insulate it from the layers 
above and below, and when in winding I arrive within an 
inch of the circumference of the reel I employ gutta-percha 
tissue in addition to the non-metallic paper." 

H is a Smee's battery, the size and power of which will 
depend on circumstances, such as the distance to which it 
is intended to convey the message ; the strength and 
direction of earth -currents; and even the state of the 
weather more power being required in dry than in damp 
weather. " For a distance of ten miles, from dotting Hill 
to Croydon, I have found a Smee's battery of two cells 
at each end, containing plates 3 by 5 inches, to suffice. 


For about fifty miles, from Nbtting Hill to Brighton, I 
have used with success a battery of three cells at each 
end ; and from dotting Hill to Bangor, in Wales, I have 
required six cells at each end. Generally speaking, I have 
found that less power is required to convey a message from 
north to south and from south to north than from east 
to west, or from west to east." 

The connections of the various instruments are shown by 
lines, and an exactly similar set of instruments is arranged 
at the place with which it is desired to correspond. 

And now as to the modus operandi: when the handle 
of the needle instrument, c, is worked in the act of signal- 
ling, what happens 1 ? Here the trouble comes in. The 
author, I regret to say, is silent as to what happens, and 
I won't be so rash as to make a guess ; but I would suggest 
the question as a safe prize-puzzle for the Questions and 
Answers column of some technical journal ! Seriously, it 
seems to me that the results, if any, must be a perfect 
chaos of battery currents, earth -battery currents, earth- 
currents, induction currents, and currents of polarisation 
all fighting in a feeble way for the mastery ; and yet 
some men, besides the author, believed these effects to 
be intelligible signals ! 

The remarks of Mr Varley, quoted above, drew that 
gentleman into an angry correspondence in the pages of 
the old 'Electrician' journal, from which I give a few 
extracts. In the number for February 20, 1863, a student 
wrote : 

"It is evident that Mr Varley must be imperfectly 
acquainted with the electric laws relating to earth con- 
duction, or, by simply replacing his delicate galvanometer 
by a few turns of stout wire, he might certainly have 
obtained the signals. What is obviously required in an 
experiment of this kind is to oppose as little resistance 


as possible to the current of derivation by which the signal 
is produced. The resistance of a galvanometer 'of the 
most sensitive kind' must clearly be enormous in com- 
parison with that of the other paths through which the 
electricity is free to pass. 

"Since the question of signalling without wires was 
first referred to in 'The Electrician,' I have myself, with 
a less power than twelve Grove cells, obtained signals 
through more than 8 yards of garden -ground ; but it is 
well known that signals have been transmitted without 
wires through a much greater distance, both in England 
and America." 

This is followed by a short letter from Mr Haworth, 
which we need not quote, as it contains nothing in the 
way of explanation. 

Mr Varley replied as follows in the next number of 
'The Electrician' (February 27, 1863): 

" I make it a rule never to pay any attention to anony- 
mous correspondents. As Mr Haworth, however, has com- 
mented upon the remarks I made a short time since at the 
Society of Arts, allow me to draw attention to the fact 
that, the discussion having been prolonged beyond the time 
allotted for that purpose, the detail of the experiments 
could not then be fully entered into. 

"Mr Haworth paid me 'one' visit a short time ago, 
when I asked him if he had any objection to his invention 
being tested by actual experiment : he said he had not, and 
pointed out to me how to arrange the various parts of the 
apparatus. I have preserved the pencil sketch made at the 
time, as indicated and approved by him. This was strictly 
followed in the experiments. 

" The apparatus used was constructed especially for this 
purpose. The primary coils were thoroughly insulated with 
gutta-percha, the secondary coils by means of a resinous 


compound and india-rubber. The plates of copper and zinc 
at each station were but an inch and a half from each 
other ; they were each 6 inches square. Th two stations 
were only 8 yards apart. 

"The apparatus at each station consisted of a plate of 
copper and a plate of zinc, connected to a flat secondary 
coil containing nearly a mile of No. 35 copper wire. The 
secondary coil was placed immediately behind the plates, 
and behind this was placed a flat primary coil. 

"At the sending station the primary coil was connected 
with six cells of Grove's battery, and contact intermitted. 
At the receiving station the primary coil was connected 
with one of Thomson's reflecting galvanometers, of small 
resistance, no more than that of an ordinary telegraph 

"With this disposition of apparatus no current could be 

"Crossing a river without wires is an old experiment. 
In March 1847 I tried experiments in my own garden, 
and also across the Eegent's Canal, with a single cell of 
Grove's battery. Feeble but evident currents were sent 
across the canal 50 feet wide. The current received was 
but a minute fraction of that leaving the battery. In this 
case the distance across the canal was but one quarter of 
that separating the plates on each bank. When, however, 
these plates were brought near together, as in Haworth's 
specification, no visible signal could be obtained. 

" This experiment has been repeated by numbers in vari- 
ous parts of the world, and with the same well-known 
results. When tried by me in 1847, I was unaware that 
the idea had occurred to Professor Morse, or any one else. 

"To account for Mr Haworth's assertions that he has 
worked from Ireland to London, and between other distant 
places, I can only suppose that he has mistaken some 


irregularity in the currents generated by his copper and 
zinc plates for signals. 

"If he can telegraph without wires, why does he not 
connect England with America, when he can earn 1000 
per diem forthwith, and confer upon the world a great 
blessing 1 

" Before speaking at the Society of Arts, I called at Mr 
Haworth's house several times, and found him out on all 
occasions. I wrote him more than once, giving him the 
negative results of my experiments, &c. He, however, 
paid no attention to any of my communications. 

" I have not been able to meet with a single individual 
who has seen a message transmitted by Mr Haworth ; and 
every one of those who are reported to have seen it, and 
with whom I have come in contact, positively deny it when 

" I have no hesitation in stating 1st, That Mr Haworth's 
specification is unintelligible : it is a jumble of induction 
plates, induction coils, and coils of wire connected together 
in a way that can have no meaning. 

" 2ndly, That he cannot send electric signals without 
wires to any useful distance. 

" Srdly, From my acquaintance with the laws of elec- 
tricity, I cannot believe it possible that he has ever com- 
municated between distant stations as stated in his speci- 
fication, No. 843, 1862. 

" 4thly, Supposing for a moment that he could work, as 
stated, any person constructing a similar apparatus in the 
neighbourhood would be able to read the communications, 
and they no longer would be private." 

In the number for March 6, 1863, Mr James M. Holt, 
writing from Kensington Park Gardens, W., said : 

"I regret that Mr Varley's experiments have proved 
unsuccessful ; but this does not surprise me, as, if I read 


his letter correctly, he did not follow Mr Haworth's specifi- 
cation closely if, indeed, at all. It would seem that he 
constructed only parts of the apparatus, and did not 
even connect those parts in the manner prescribed in the 

" I have seen Mr Haworth's apparatus at work repeatedly, 
and have myself read off from the indicator the messages 
which have arrived and these ' irregular currents mistaken 
for signals' have consisted of words and sentences trans- 
mitted as correctly as by the electric telegraph. My house 
has been one station, and Brighton, or Kingstown in 
Ireland, the other. 

"I can certify that the delay in bringing out this 
discovery arises from causes over which Mr Ha worth has no 
control. Accident has injured his apparatus. He will be 
delighted to transmit signals across the Atlantic as soon as 
the necessary machinery is ready, but he considers not 
unwisely that it is most important to make success doubly 
sure by previous repeated tests and experiments." 

This is followed by two letters from other eyewitnesses, 
vouching for the success of Haworth's experiments, and the 
correspondence concludes with the following letter from Mr 
Haworth himself : 

"SiR, Will you kindly allow me space for a line in 
reply to Mr Yarley 1 I never received his letter of the 27th 
of January, and am truly sorry for any apparent discourtesy 
on my part. I fear other letters have shared the same fate. 

"From Mr Yarley 's account of his experiments I find 
several particulars in which there has been considerable 
misapprehension on his part ; but I cannot spare the time 
nor can I ask you for the space to give further explana- 
tions. It certainly is a new feature in electricity, if the 
earth's currents alone can register words and sentences on 



the dial-plate. I hope shortly to be able to convince the 
most sceptical by ocular demonstration. For the present I 
am content to wait, being anxious rather to perfect my dis- 
covery than to push it. I am, sir, yours truly, 


"March 3, 1863." 

After this we hear nothing more of Mr Haworth, though 
no doubt the publication and discussion of his views kept 
the subject alive for a time. 1 Thus, in ' The Electrician ' 
for January 23, 1863, the editor has a long article on " The 
Earth as Part of a Voltaic Circuit," in which he reviews the 
problem so well that we cannot refrain from quoting him 
largely. He says : 

" The case, communicated by ' E. S. ' and corroborated 
by Mr R S. Culley, of a telegraphic circuit being worked 
through a broken wire, the ends of which were in contact 
with earth, appears in some quarters to have been taken in 
confirmation of the notion that electric signals may be 
transmitted to any required distance without the use of 
a metallic conductor. It may be necessary, therefore, to 
point out that this supposed confirmation has no existence 
in fact. There are no grounds whatever for supposing that 
any case similar to those which have been noticed by our 
correspondents is not susceptible of being readily explained 
in accordance with the known laws of electrical science. It 
is altogether different when we come to the practical pro- 
blem of signalling by electricity without a conducting wire. 
If we have hitherto been silent in regard to this question, 
which seems to have latterly engaged some amount of public 
attention, it is that the means proposed for its solution are, 

1 In Boron's ' Me'te'orologie Simplified,' Paris, 1863, pp. 936, 937, 
there is a hazy description of a wireless telegraph, apparently based 
on the same lines as Haworth's. 


to us, simply incomprehensible. We cannot dispute their 
efficiency, since we are forced to admit that we cannot per- 
ceive upon what principle efficiency is aimed at. While, 
in such case, it would clearly be unjustifiable to deny with- 
out disproving, or to use the word ' impossible ' in reference 
to what has been put forward as an accomplished fact, the 
only alternative is to await, ' with modest scepticism,' the 
verification and elucidation of the ' fact ' thus asserted. 

" To render intelligible the phenomenon observed in the 
broken wire circuit, we must have recourse to the law of 
derived currents. Divested of all technicality, this is 
simply that, when several conducting paths are offered for 
the passage of a current, the quantity of electricity travers- 
ing each path respectively will be inversely proportionate 
to its resistance. If, therefore, in this instance, the resist- 
ance between the broken extremities of the wire, added to 
the resistance of the wire from the point of rupture to the 
' line ' earth - plate, plus the resistance between the two 
earth-plates, be less than the resistance between the broken 
portion of the wire in contact with earth and the battery 
earth -plate, the quantity of electricity traversing the sig- 
nalling instrument at the distant station cannot be reduced 
to the extent of one - half the normal signalling power. 
Under these circumstances, therefore, signals might be re- 
ceived almost as usual. Provided that the earth connections 
of the main circuit were very perfect, and the point of rup- 
ture nearer to the receiving than to the sending station, or 
that the broken ends of wire were resting upon ground 
freshly moistened by rain and covering a dry substratum, 
it is quite possible that the signals would not be very per- 
ceptibly reduced. . . . 

" We pass over some other experiments of interest in 
connection with earth conduction, in order to make out the 
best case possible for those who believe in the present 



practicability of signalling by means of voltaic electricity, 
without any insulation between the two halves of the cir- 
cuit. Instead of placing our interposed plates in a direct 
line between the earth-plates in a circuit, let us arrange 
them in a path which must be traversed by an indirect or 
derived current, as in the following figure, in which B is the 
battery, E + and E - the two earth-plates, and e e the two 
interposed plates. 

Fig. 7. 

" At whatever distance the two systems may be placed 
apart, a current will undoubtedly traverse the galvanometer 
between the plates e e', whenever the circuit of the battery 
is completed. We make the admission unreservedly, from 
the point of view of theory ; the practical deductions to be 
drawn from it have yet to be considered. We have to cal- 
culate the force of the current which may traverse from 
e to e' through the galvanometer or receiving instrument, or, 
in other words, the proportionate quantity of electricity 
taking this path, compared with the total dynamic effect of 
the battery. 


" Now we have reason to believe that something like the 
following plausible method of arriving at a conclusion upon 
this point is adopted by some of the more advanced among 
those who hold the untenable view above referred to : 

" ' Let the wire and battery resistance in the " transmit- 
ting system," E + , B, E - , equal 1000 units ; 

"'The resistance of the receiving system e e', equal 100 
units ; 

" ' And let the resistance between the earth- plates E + 
and E , and between E + and e, and E - and e', be inappre- 

" ' Then the resistance in the direct circuit completed by 
the battery plates E + and E will equal 1000. 

" ' And the total resistance in the indirect circuit through 
e e', will equal 1100 units. 

" ' And, by the law of derived currents, if the force of 
the current traversing the direct circuit be represented by 
1100, that of the current traversing e e' will be 1000.' 

"It will be scarcely necessary for us to point out the 
fallacy of this mode of reasoning. It assumes the existence 
of two paths only for the return currents the path of least 
resistance between E + and E , and that through e e'. But 
it will readily be seen that the earth affords a multitude of 
paths of conduction for the earth portion of the circuit, of 
which that from e to e' is one. The latter is therefore in- 
cluded in the resistance between the earth-plates E + and 
E- specified as inappreciable. As this inappreciable re- 
sistance is to the resistance of wire from e to e', so will be 
the relative force of the currents traversing the transmitting 
and receiving systems respectively. The ratio, in a circuit, 
without metallic conduction of moderate length, approxi- 
mates to that of infinitely great to infinitely small. Can 
any practical system be based upon these data?" 


J. H. MOWER 1868. 

Of the next proposal with which we have to deal in 
these pages, I find amongst my notes only a single 
cutting from the New York 'Kound Table' of (August 
or September) 1868. I give it, in extenso, for what 
it is worth, and hope some American reader may be 
able to furnish details and further developments if 
any : 

"Mr Mower has elaborated a discovery which, if the 
description given by the 'New York Herald' is to be 
relied upon, will revolutionise trans-oceanic, and generally 
all subaqueous, telegraphy. For some years he had been 
engrossed in electrical experiments, when the Atlantic 
cable gave a special direction to his investigations into 
generating and conducting substances, the decomposition 
of water, the development of the electrical machine, &c., &c. 
By this summer his arrangements had been so far perfected 
that, a few weeks ago, he was able to demonstrate to 
himself and his coadjutor the feasibility of his project, 
on a scale approximate to. that which it is designed to 

" Selecting the greatest clear distance on an east and 
west line in Lake Ontario from a point near Toronto, 
Canada West, to one on the coast of Oswego County, New 
York at his first attempt he succeeded in transmitting his 
message, without a wire, from the submerged machine at 
one end of the route to that at the other. The messages 
and replies were continued for two hours, the average time 
of transmission for the 138 miles being a little less than 
three-eighths of a second. 

"The upshot of the discovery on what principle Mr 
Mower is not yet prepared to disclose is, that electric 


currents can be transmitted through water, salt or fresh, 
without deviation vertically, or from the parallel of lati- 
tude. The difficulty from the unequal level of the tidal 
waves in the two hemispheres will be obviated, it is 
claimed, by submerging the apparatus at sufficient depth. 
The inventor, we are told, is preparing to go to Europe 
to secure there the patent rights for which the caveats have 
been filed here. At the inconsiderable cost of 10,000 
dollars he expects within three months to establish tele- 
graphic communication between Montauk Point, the eastern 
extremity of Long Island, and Spain, the eastern end of 
the line striking the coast of Portugal at a point near 

" The statement of the discovery is enough to take away 
one's breath ; but, with the history of the telegraph before 
us, we no more venture to deny than we do to affirm 
its possibility." 


During the' investment and siege of Paris by the German 
forces in the winter of 1870-71, many suggestions were 
made for the re-establishment of telegraphic communica- 
tion between Paris and the provinces. Acoustic methods 
were tried, based on the transmission of sound by earth 
and water. A Mr Granier proposed a form of aerial line 
which was thought to be feasible by the distinguished 
aeronaut, Gaston Tissandier. The wire (to be paid out 
from balloons) was to be enclosed in gutta-percha tubing, 
inflated with hydrogen gas so as to float 1000 to 1500 
metres above the earth. 

Amongst other suggestions was one by M. Bourbouze, 
a well-known French electrician, which only need concern 


us in these pages. 1 His proposal was to send strong 
currents into the river Seine from a battery at the nearest 
approachable point outside the German lines, and to receive 
in Paris through a delicate galvanometer such part of these 
currents as might be picked up by a metal plate sunk in 
the river. After some preliminary experiments between 
the Hotel de Ville and the manufactory of M. Claparede 
at St Denis, it was decided to put the plan in practice. 
Accordingly, on December 17, 1870, M. d' Almeida left the 
beleaguered city by balloon, descended after many perils 
at Champagne outside the enemy's lines, and proceeded 
via Lyons and Bordeaux to Havre. Thence the necessary 
apparatus was ordered from England and conveyed to 
Poissy, where M. d'Almeida regained the banks of the 
Seine on January 14, 1871. Here, however, the river 
was found to be completely frozen over, and the attempt 
at communicating with Paris was deferred to January 24. 
Meanwhile the armistice was proclaimed, and the project 
was allowed to drop. 

M. Bourbouze did not, however, abandon his idea, and, 
thinking he found in the principle of La Cour's phonic wheel 
telegraph a better means of indicating the signals than the 
galvanometer, he again took up the problem. Between 1876 
and 1878 an occasional notice of his experiments appeared 
in the technical journals, but they are all provokingly silent 
on the point of actual results over considerable distances. 2 

1 On March 27, 1876, Bourbouze requested to be opened at the 
Academy of Sciences a sealed packet which he had deposited on 
November 28, 1870. It was found to contain a note entitled " Sur 
les Communications a Distance par les Cours d'Eau." The contents 
of the document, so far as I know, have not been published. 

2 See, amongst other accounts, the ' English Mechanic,' September 
8, 1876 ; ' Engineering,' April 13, 1878 ; and the French journal, ' La 
Nature,' July 8, 1876. For Bourbouze's earlier experiments, see ' La 
Lumiere Electrique,' August 19, 1879. 



In 1872 Mr Mahlon Loomis, an American dentist, pro- 
posed to utilise the electricity of the higher atmosphere for 
telegraphic purposes in a way which caused some excite- 
ment in America at the time. 

It had long been known that the atmosphere is always 
charged with electricity, and that this charge increases 
with the ascent : thus, if at the surface of the earth we 
represent the electrical state or charge as 1, at an elevation 
of 100 feet it may be represented as 2 ; at 200 feet as 3 ; 
and so on in an ascending series of imaginary strata. 
Hitherto this had been considered as a rough-and-ready 
way of stating an electrical fact, just as we say that the 
atmosphere itself may, for the sake of illustration, be 
divided into strata of 100 or any agreed number of feet, 
and that its density decreases pro rata as we ascend through 
each stratum. But Mr Loomis appears to have made the 
further discovery that these electrical charges are in some 
way independent of each other, and that the electricity of 
any one stratum can be drawn off without the balance being 
immediately restored by a general redistribution of elec- 
tricity from the adjacent strata. On this assumption, 
which is a very large one, he thought it would be easy to 
tap the electricity at any one point of a stratum, preferably 
an elevated one where the atmosphere is comparatively 
undisturbed, which tapping would be made manifest at 
any distant point of the same stratum by a corresponding 
fall or disturbance there of the electrical density ; and thus, 
he argued, an aerial telegraph could be constructed. 

The following is an extract from his (American) patent, 
dated July 30, 1872 : 

" The nature of my discovery consists in utilising natural 


electricity, and establishing an electrical current or circuit 
for telegraphic and other purposes without the aid of wires, 
artificial batteries, or cables, and yet capable of communi- 
cating from one continent of the globe to another. 

" As it was found possible to dispense with the double 
wire (which was first used in telegraphing), making use of 
but one, and substituting the earth instead of a wire to 
form the return half of the circuit ; so I now dispense with 
both wires, using the earth as one-half the circuit and the 
continuous electrical element far above the earth's surface 
for the other half. I also dispense with all artificial bat- 
teries, but use the free electricity of the atmosphere, co- 
operating with that of the earth, to supply the current for 
telegraphing and for other useful purposes, such as light, 
heat, and motive power. 

"As atmospheric electricity is found more and more 
abundant when moisture, clouds, heated currents of air, 
and other dissipating influences are left below and a greater 
altitude attained, my plan is to seek as high an elevation as 
practicable on the tops of high mountains, and thus establish 
electrical connection with the atmospheric stratum or ocean 
overlying local disturbances. Upon these mountain-tops I 
erect suitable towers and apparatus to attract the electricity, 
or, in other words, to disturb the electrical equilibrium, and 
thus obtain a current of electricity, or shocks or pulsations, 
which traverse or disturb the positive electrical body of the 
atmosphere between two given points by connecting it to 
the negative electrical body of the earth below." 

To test this idea, he selected two lofty peaks on the 
mountains of West Virginia, of the same altitude, and about 
ten miles apart. From these he sent up two kites, held by 
strings in which fine copper wires were enclosed. To the 
ground end of the wire on one peak he connected an electrical 


detector presumably of the electrometer kind and on the 
other peak a key for connecting the kite wire to earth when 
required. With this arrangement we are told that messages 
were sent and received by making and breaking the earth 
connection, "the only electro-motor being the atmospheric 
current between the kites, and which was always available 
except when the weather was violently broken." 

So well did this idea " take on " in the States that we 
learn from the New York * Journal of Commerce ' (February 
5, 1873) that a bill had passed Congress incorporating a 
company to carry it out. The article then goes on to say : 
" We will not record ourselves as disbelievers in the Aerial 
Telegraph, but wait meekly and see what the Doctor will 
do with his brilliant idea now that both Houses of Congress 
have passed a bill incorporating a company for him. Con- 
gressmen, at least, do not think him wholly visionary ; and 
it is said that the President will sign the bill ; all of which 
is some evidence that air telegraphy has another side than 
the ridiculous one. The company receive no money from 
the Government, and ask none. As we understand the 
Loomis plan, it is something to this effect and readers are 
cautioned not to laugh too boisterously at it, as also not to 
believe in it till demonstrated. The inventor proposes to 
build a very tall tower on the highest peak of the Eocky 
Mountains. A mast, also very tall, will stand on this 
tower, and an apparatus for ' collecting electricity ' will top 
the whole. From the loftiest peak of the Alps will rise 
another very tall tower and ditto mast, with its coronal 
electrical affair. At these sky-piercing heights Dr Loomis 
contends that he will reach a stratum of air loaded with 
electricity ; and we cannot say that he will not. Then, 
establishing his ground-wire connections the same as in 
ordinary telegraphs, he feels confident that he can send 


messages between the mast-tops, the electrified stratum of 
air making the circuit complete. The inventor claims to 
have proved the feasibility of this grand scheme on a small 
scale. We are told that, from two of the spurs of the Blue 
Eidge Mountains, twenty miles apart, he sent up kites, 
using small copper wire instead of pack-thread, and tele- 
graphed from one point to the other." 

At intervals in the next few years brief notices of the 
Loom is method appeared in the American journals, some 
of which were copied into English papers. The last that 
I have seen is contained in the 'Electrical Eeview' of 
March 1, 1879, where it is stated that "with telephones in 
this aerial circuit he (Loomis) can converse a distance of 
twenty miles," to which the editor significantly adds a 
note of interrogation. 

The fact is, however much Mr Loomis and his Wall 
Street friends believed that dollars were in the idea, the 
technical press never took it very seriously. This is shown 
by the following cutting, which we take from the New 
York 'Journal of the Telegraph,' March 15, 1877: 
"The never-ending procession of would-be inventors who 
from day to day haunt the corridors and offices of the 
Electrician's department at 195 Broadway, bringing with 
them mysterious packages tied up in newspapers, was 
varied the other day by the appearance of a veritable 
lunatic. He announced that that much -talked -of great 
discovery of a few years ago, aerial telegraphy, was in 
actual operation right here in New York. A. M. Palmer, 
of the Union Square Theatre, together with one of his 
confederates, alone possessed the secret ! They had un- 
fortunately chosen to use it for illegitimate purposes, and 
our visitor, therefore, felt it to be his solemn duty to expose 
them. By means of a $60,000 battery, he said, they trans- 


mitted the subtle fluid through the aerial spaces, read 
people's secret thoughts, knocked them senseless in the 
street ; ay, they could even burn a man to a crisp, miles 
and miles away, and he no more know what had hurt him 
than if he had been struck by a flash of lightning, as indeed 
he had ! J The object of our mad friend in dropping in was 
merely to ascertain how he could protect himself from 
Palmer's illegitimate thunderbolts. Here the legal gentle- 
man, lifting his eyes from ' Curtis on Patents/ remarked : 
*Xow, I'll tell you what you do. Bring a suit against 
Palmer for infringement of Mahlon Loomis's patent. Here 
it is ' (taking down a bound volume of the 'Official Gazette '), 
1 No. 129,971. That'll fix Palmer.' But the madman pro- 
tested that this would take too long, and meanwhile he was 
in danger of his life every minute, and casually remarked 
that it had occurred to him that by appearing on the streets 
in a robe of pea-green corded silk, gutta-percha boots, and a 
magenta satin hat with a blue-glass skylight in the top of it, 
he would be effectually protected from injury during his 
daily perambulations." 

In conclusion of this period of our history, it will suffice 
to say that between 1858 and 1874 many patents were 
taken out in England for electric signalling on the bare 
wire system of Highton and Bering, with or without the 
use of the so-called " earth battery." As they are all very 
much alike, and all unsupported, so far as I have seen, by 
any experimental proofs, it would be a tiresome reiteration 
to describe them, even in the briefest way. I therefore 
content myself with giving the following list, which will 
be useful to those of my readers who desire to consult 

1 This lunatic must be still abroad, for we occasionally hear much 
the same thing of the diabolic practices of Tesla and Marconi. 



Name of patentee. 
B. Nickels . ... 
A. V. Newton . . 
A. Barclay . . . 

Do. ... 
J. Moles worth , . 
H. S. Eosser . . 
W. E. Newton . . 
H.Wilde . . . 
Lord A. S. Churchill . 
H.Wilde . . . 

Do. ... 
T. Walker . . , . 


No. and date of patent. 

2317 October 16, 1858. 

2514 November 9, 1858. 

56 January 7, 1859. 

263 January 28, 1859. 

687 March 18, 1859. 

2433 October 25, 1859. 

1169 May 11, 1860. 

2997 November 28, 1861. 

458 February 20, 1862. 

3006 December 1, 1863. 

2762 October 26, 1865. 

2870 November 6, 1866. 

293 January 23, 1874. 




- . " Give me the ocular proof, 

Make me see't ; or, at least, so prove it, 
That the probation bear no hinge, nor loop, 
To hang a doubt on." 

WE have now arrived at a period in the history of our 
subject at which experiments begin to assume a character 
more hopeful of practical results. All that went before 
was more or less crude and empirical, and could not be 
otherwise from the very necessities of the case. The intro- 
duction of the telephone in 1876 placed in the hands of the 
electrician an instrument of marvellous delicacy, compared 
with which the most sensitive apparatus hitherto employed 
was as the eye to the eye aided by the microscope. Thus, 
Prof. Pierce of Providence, Ehode Island, has found that 
the Bell telephone gives audible signals with consider- 
ably less than one-hundred-thousandth part of the current 
of a single Leclanche cell. In testing resistances with a 
Wheatstone bridge, the telephone is far more sensitive than 
the mirror galvanometer ; in ascertaining the continuity of 
fine wire coils it gives the readiest answers ; and for all the 
different forms of atmospheric electrical discharges and 


they are many it has a language of its own, and opens up 
to research a new field in meteorology. 

The sound produced in the telephone by lightning, even 
when so distant that only the flash can be seen in the hori- 
zon, and no thunder can be heard, is very characteristic 
something like the quenching of a drop of molten metal in 
water, or the sound of a distant rocket ; but the remarkable 
circumstance for us in this history is, that this sound is 
always heard just before the flash is seen, showing that 
there is an inductive disturbance of the electricity overhead, 
due to the distant concentration preceding the disruptive 
discharge. Thus, on November 18, 1877, these peculiar 
sounds were heard in Providence, and the papers next 
morning explained them by reporting thunderstorms in 
Massachusetts. Sounds like those produced by lightning, 
but fainter, are almost always heard many hours before a 
thunderstorm actually breaks. 1 

The Bell telephone was tried for the first time on a wire 
from New York to Boston on April 2, 1877, and soon after- 
wards its extraordinary sensitiveness to induction currents, 
and currents through the earth (leakages) from distant 
telegraph circuits, began to be observed. 2 Thus, in August 
1877, Mr Charles Eathbone of Albany, KY., had been ex- 
perimenting with a Bell telephone which was attached to a 
private telegraph line connecting his house with the Ob- 

1 'Journal of the Telegraph,' N.Y., December 1, 1877. See also 
'Jour. Inst. Elec. Engs.,' vol. vi. p. 523, vol. vii. p. 329; 'The Elec- 
trician,' vol. ix. p. 362. 

2 The disturbing effects of induction on ordinary telegraph wires on 
the same poles had long before this been noticed. See Culley's paper 
and the discussion thereon in the 'Jour. lust. Elec. Engs.,' vol. iv. 
p. 54. See also p. 427 for Winter's interesting observations in India 
in 1873. As far back as 1868 Prof. Hughes, at the request of the 
French Telegraph Administration, undertook a series of experiments 
with a view of finding a remedy. The results are given in his paper 
read before the Inst. Elec. Engs., March 12, 1879. 


servatory. One evening he heard some singing which he 
thought came from the Observatory, but found on inquiry 
that that was not the case. He then carefully noted what 
followed, and next morning sent a note to the newspapers 
stating the facts and giving the names of the tunes which 
he had heard. This elicited the information that the tunes 
were those of an experimental concert with Edison's singing 
telephone over a telegraph wire between New York and 
Saratoga Springs. It was then resolved to follow up this 
curious discovery, and, accordingly, when Edison's agent 
gave another concert in Troy, arrangements were made to 
observe the effects. A wire running from Albany to Troy 
alongside the Edison wire was earthed with a Bell telephone 
in circuit at each end. The concert was heard as before, 
the music coming perfectly clear, and the tunes distinguish- 
able without the least difficulty. 

Later in the evening the instruments were put in circuit 
on one of the wires running from Albany to New York. 
Again the music was heard, and much louder, so that by 
placing the telephone in the centre of the room persons 
seated around could hear with perfect distinctness. 

These observations were made on six separate occasions 
between August 28 and September 11, and, strangely enough, 
two other and independent observers in Providence, 200 
miles away, noted the same effects on five out of the six 
dates given by Mr Rathbone. 1 

Dr Channing, one of the observers in Providence, has 
published a very interesting account 2 of his observations, 
from which I will make a few extracts. During five 

1 'Journal of the Telegraph,' N.Y., October 1 and 16, and No- 
vember 1, 1877. For other early observations of the same kind see 
'The Telegraphic Journal,' March 1, 1878, p. 96 ; 'Journal of the 
Telegraph,' March 16, 1878 ; ' The Electrician,' vol. vi. pp. 207, 303. 

2 'Journal of the Telegraph,' December 1, 1877, and reproduced 
in the 'Jour. Inst. Elec. Engs.,' vol. vi. p. 545. 



evenings in the latter part of August and first part of 
September 1877 concerts were given in the Western Union 
Office, N.Y., for the benefit of audiences in Saratoga, 
Troy, and Albany respectively. The performers sang or 
played into an Edison musical telephone, actuated by a 
powerful battery, and connected with one or other of the 
above-named places by an ordinary telegraph line, with 
return through the ground. 

In Providence, on the evening of the first concert, Dr 
Channing and a friend were conversing through Bell tele- 
phones over a shunt wire, made by grounding one of the 
American District Telegraph wires at two places, a quarter 
of a mile apart, through the telephones and several hun- 
dred ohms resistance. At about half-past eight o'clock 
they were surprised by hearing singing on the line, at first 
faint, but afterwards becoming clear and distinct. After- 
wards, during that and subsequent evenings, various airs 
were heard, sung by a tenor or soprano voice, or played 
on the cornet. On investigation, the music heard proved 
to be the same as that of the Edison concerts performed 
in New York. 

The question how this music passed from the New York 
and Albany wire to a shunt on the District wire in Provi- 
dence is of scientific importance. The Edison musical 
telephone consists of an instrument which converts sound 
waves into galvanic waves at the transmitting station, and 
another apparatus which reconverts galvanic waves into 
sound waves at the receiving station. The battery used 
in these concerts consisted of 125 carbon-bichromate cells 
(No. 1J), with from 1000 to 3000 ohms resistance inter- 
posed between the battery and the line. The line wire 
extended from the Western Union office, via the Harlem 
Eailway, to Albany. On the same poles with this Albany 
wire, for sixteen miles, are carried four other wires, all 


running to Providence, and also, for eight miles, a fifth 
wire from Boston, via New London, to Providence. All 
these lines, including the Albany wire, are understood to 
have a common earth connection at New York, and to be 
strung at the usual distance apart, and with the ordinary 

At Providence six New York and Boston wires run 
into the Western Union office on the same poles and 
brackets for the last 975 feet with an American District 
wire. This wire belongs to an exclusively metallic circuit 
of four and a half miles, having, therefore, no earth con- 
nection. Finally, in a shunt on this wire, the telephones 
were placed as before described. 

It will thus be seen that the music from the Albany 
wire passed first to the parallel New York -Providence 
wires; secondly, from these to a parallel District wire in 
Providence ; and thirdly, through a shunt on the "District 
wire "to the telephones. 

This transfer may have taken place by induction, by 
cross-leakage, or, in the first instance, in New York by 
a crowded ground connection ; but in the transfer in Provi- 
dence from the New York-Boston to the District wire there 
was no common ground connection, and it is difficult to 
suppose that sufficient leakage took place on the three 
brackets and three poles (common to the New York and 
District wires) to account for it. Without wholly reject- 
ing the other modes of transfer, Dr Channing ascribes to 
induction the principal part in the effects. 

The next question arises, What proportion of the electri- 
cal force set in motion in New York could have reached the 
listeners on the short shunt line in Providence 1 Whether 
induction or cross-leakage or crowded ground was concerned, 
who will say that the New York -Providence wires had 
robbed the Albany wire of one-tenth or even one-hundredth 


of its electrical force 1 When this reached Providence, did 
the New York wires in the course of 975 feet give up to 
the District wire one-tenth or one-hundredth of their force 1 
Lastly, when the District circuit had secured this minute 
fraction, did the shunt, with its 500 ohms resistance as 
against the few ohms of the shunted quarter-mile, divert 
one-hundredth part of this minute fraction from the Dis- 
trict wire ] Plainly, the music reproduced in the Providence 
telephone did not require one ten - thousandth, nor one 
hundred-thousandth of the force originally imparted to the 
Albany wire. 

In December 1877 Prof. E. Sacher of Yienna undertook 
some careful investigations with a view of measuring the 
inductive effect in telephone circuits. He found that 
signals from three Smee cells sent through one wire, 120 
metres long, could be distinctly heard in the telephone on 
another and parallel wire 20 metres distant from it. 1 

Early in 1879 M. Henri Dufour tried similar experi- 
ments, and with the same results. Two covered copper 
wires were stretched parallel over a length of 15 metres, and 
at distances apart varying from 15 to 45 centimetres. In 
connection with one of the wires were the battery and the 
ordinary Morse apparatus, the gas -pipes being used to com- 
plete the circuit. The ends of the other wire were joined 
to the telephone so as to form a complete metallic circuit. 
The current employed produced a deflection of 60 on the 
galvanometer. Under these conditions all the motions of 
the key were distinctly heard in the telephone, and the 
author was satisfied that a telegraphist would have under- 
stood the signals, even when the distance between the two 
wires was 45 centimetres. 2 

When we consider the shortness of these wires, the 
effects are sufficiently striking ; but before this, equally 
1 Electrician, vol. i. p. 194. 2 Ibid., vol. ii. p. 182. 


striking results had been obtained on actual telegraph lines, 
where there was no battery, and where the infinitesimal 
currents produced by speaking into a Bell telephone on one 
wire were able to induce currents in a parallel wire sufficient 
to render the words audible in another telephone in its 
circuit. Dr Channing found this to be possible "under 
very favourable conditions." l 

Another striking illustration is furnished by Prof. Blake, 
of Brown University, U.S., who talked with a friend for 
some distance along a railway (using the two lines of rails 
for the telephonic circuit), hearing at the same time the 
Morse signals passing along the telegraph wires overhead. 2 


Such are a few of the early instances noted of the 
extreme sensitiveness of the telephone, by the aid of which 
the problem of wireless telegraphy was now to be attacked 
with a fair measure of success, and advanced a long way 
towards a practical solution. 

Mr J. Gott, then superintendent of the Anglo-American 
Telegraph Company at St Pierre, was, I believe, the first to 
suggest the employment of the telephone in this connection. 
In a brief communication, published in the ' Jour. Inst. 
Elec. Engs.' (vol. vi. p. 523), he says: "The island of 

1 For a curiously similar case, the result of a wrong connection of 
the line wires, see the ' Telegraphic Journal,' vol. ix. p. 68. 

2 The absence of insulation in this experiment recalls the fact that 
a telephone line using the earth for the return circuit often works 
better when the insulation is defective, as it is then less affected by 
extraneous currents. Thus, in 1882, the Evansville (Ind.) Telephone 
Exchange Company worked 400 miles of line without insulators of any 
kind (the wires being simply attached to the poles), and generally 
with better results than when insulators were used. (' Electrician,' 
vol. ix. p. 481.) 


St Pierre is, perhaps, better insulated than most places. 
Hundreds of yards from the station, if a wire be connected 
to earth, run some distance, and put to earth again, with a 
telephone in circuit, the signals passing through the cables 
can be heard." 

There are two offices on the island, one used for 
repeating the cable business on the short cables between 
Sydney, C.B., and Placentia, KF., and operated by the 
Morse system, with a comparatively powerful battery ; the 
other is the office at which the Brest and Duxbury cables 
terminate, and is furnished with very delicate instruments 
the Brest cable, which is upwards of 2500 miles long, 
being operated by Thomson's exceedingly sensitive dead- 
beat mirror galvanometer ; whilst on the Duxbury cable the 
same inventor's instrument, the siphon recorder, is used. 
The Brest instrument was found seriously affected by earth- 
currents, which flowed in and out of the cable, interfering 
very much with the true currents or signals, and rendering 
it a difficult task for the operator to decipher them ac- 
curately. The phenomenon is not an uncommon one ; and 
the cause being attributed to the ground used at the 
office, a spare insulated wire, laid across the island, a 
distance of nearly three miles, and a metal plate connected 
to it and placed in the sea, was used in lieu of the office 
ground. This had a good effect, but it was now found that 
part of the supposed earth-currents had been due to the 
signals sent by the Morse operator into his wire, for when 
the recorder was put in circuit between the ground at the 
cable office and the sea ground three miles distant the 
messages sent by the Morse were clearly indicated, so 
clearly, in fact, that they were automatically recorded on 
the tape. 

It must be clearly understood that the two offices were in 
no way connected, nor were they within some 200 yards of 


each other; and yet messages sent at one office were 
distinctly read at the other, the only connection between 
the two being through the earth, and it is quite evident 
that they could be so read simultaneously at many offices in 
the same neighbourhood. The explanation is clear enough. 
The potential of the ground at the two offices is alternately 
raised and lowered by the Morse battery. The potential of 
the sea remains almost, if not wholly, unaffected by these, 
and the island thus acts like an immense Ley den jar, con- 
tinually charged by the Morse battery and discharged, in 
part, through the short insulated line. Each time the 
Morse operator depressed his key he not only sent a current 
into his cable, but electrified the whole island, and this 
electrification was detected and indicated on the recorder. 1 

As the result of these experiences, Mr Gott gave it as his 
opinion that "speaking through considerable distances of 
earth without wires is certainly possible with Bell's tele- 
phone, with a battery and Morse signals." 

Professor John Trowbridge of Harvard University, 
America, was, however, the first to systematically study 
the problem, and to revive the daring project of an Atlantic 
telegraph without connecting wires, and the less ambitious 
but equally useful project of intercommunication between 
ships at sea. 2 In fact, Trowbridge' s researches may truly be 

1 See now Salvd's curious anticipation in 1795 of this phenomenon, 
p. 1, ante. The peculiarity, due to geological formation, is not con- 
fined to St Pierre ; it is often met with in practice, though usually in 
lesser degrees. See some interesting cases, noted by G. K. Winter 
and James Graves, ' Jour. Inst. Elec. Engs.,' vol. L p. 88, and vol. 
iv. p. 34. 

2 Mr H. C. Strong of Chicago, Illinois, claims to have suggested 
in 1857, in a Peoria, 111., newspaper, the possibility of communication 
between ships at sea by means of a wireless telegraph then recently 
invented by his friend Henry Nelson of Galesburg. See Mr Strong's 
letter in the New York 'Journal of the Telegraph/ August 15, 


said to form a new starting-point in the history of our 
subject, for, as we shall see later on, it is chiefly to him 
that Messrs Preece, Bell, and other experimenters in this 
field owe their inspirations. His investigations, therefore, 
deserve to be carefully followed. 1 

The observatory at Harvard transmits time-signals from 
Cambridge to Boston, a distance of about four miles, and 
the regular recurrence of the beats of the clock afforded 
a good means of studying the spreading of the electric 
currents from the terminal of the battery which is grounded 
at the observatory. In all the telephone circuits between 
Boston and Cambridge, in the neighbourhood of the observ- 
atory line, the ticking of the clock could be heard. This 
ticking had been attributed to induction, but this, accord- 
ing to Prof. Trowbridge, is an erroneous conclusion, as he 
shows by a mathematical analysis into which we need not 
enter. The result goes to show that, with telephones of 
the resistance usually employed, no inductive effect will 
be perceived by the use of even ten quart Bunsen cells 
between wires running parallel, a foot apart, for a distance 
of 30 or 40 feet. 

For this and other reasons, he says, it is impossible to 
hear telephonic messages by induction from one wire to 
another, unless the two run parallel and very close to each 
other for a long distance. This distance generally exceeds 
the limit at which the ordinary Bell telephone ceases to 
transmit articulate speech. The effects which have usually 
been attributed to induction are really, he says, due to the 
earth connections and to imperfect insulation. 

Having determined in this manner that the echoes of the 

1 They are given at length in a paper, " The Earth as a Conductor 
of Electricity," read before the American Academy of Arts and 
Sciences in 1880. See also * Silliman's American Journal of 
Science,' August 1880, which I follow in the text. 


time-signals observed on the telephone lines were not due 
to induction, but to leakage from the clock circuit, Prof. 
Trowbridge proceeded to study the extent of the equally 
electrified or equi- potential surfaces of the ground sur- 
rounding the clock battery. His method of exploration 
was to run a wire 500 or 600 feet long to earth at each 
end, including a telephone of 50 to 60 ohms resistance. 
Evidence of a current in this exploratory circuit was plainly 
shown by the ticking sound which making and breaking 
the circuit caused in the telephone, and the time-signals 
could be distinctly heard in a field 220 yards from the 
observatory where one earth of the time-signal wire is 
located. At a distance of a mile from the observatory, and 
not in the direct line between that place and the Boston 
telephone office, the time-signals were heard by connecting 
through a telephone the gas-pipes of one building with the 
water-pipes of another only 50 feet apart. In another ex- 
periment at the Fresh Pond lake in Cambridge, signals 
sent from Boston to Waltham (ten to twelve miles) were 
heard by simply dipping the terminal wires of the telephone 
in the lake, and some distance apart, where they must have 
been far away (? four miles) from the battery earth. 

Prof. Trowbridge performed a large number of similar 
experiments, varied in every way, all going to prove (1) 
that a battery terminal discharging electricity to earth is 
the centre of waves of electrical energy, ever widening, 
and ever decreasing in strength or potential as they widen ; 
and (2) that on tapping the earth in the way described at 
two points of different potentials (not very distant, if near 
the central source, and more removed the farther we recede 
from the source) we can obtain in the telephone evidence 
of their existence. Prof. Trowbridge then goes on to 
say : 

" In a discussion on the earth as a conductor, Steinheil 


says : 1 ' We cannot conjure up gnomes at will to convey 
our thoughts through the earth. Nature has prevented 
this. The spreading of the galvanic effect is proportional 
... to the square of the distance ; so that, at the distance 
of 50 feet, only exceedingly small effects can be produced. 
. . . Had we 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 con- 
ducting wires.' 

"The telephone of Prof. Bell, though far from fulfilling 
the conditions required by Steinheil, is nevertheless our 
nearest approach to the desideratum. 

"The theoretical possibility of telegraphing across the 
Atlantic without a cable is evident from the survey which 
I have undertaken. The practical possibility is another 
question. Powerful dynamo - electric machines could be 
placed at some point in Nova Scotia, having one end of 
their circuit grounded near them and the other end grounded 
in Florida, the connecting wire being of great conductivity 
and carefully insulated throughout. By exploring the coast 
of France, two points on surface lines not at the same 
potential could be found; and by means of a telephone 
of low resistance, Morse signals sent from Nova Scotia 
to Florida could be heard in France. Theoretically, this 
is possible; but practically, with the light of our present 
knowledge, the expenditure of energy on the dynamo- 
electric machines would be enormous." 2 

Professor Trowbridge has suggested the applicability of 
this method to the intercommunication of ships at sea. 

1 See p. 5, ante. 

2 A writer in the 'Electrician' (vol. v. p. 212), commenting on 
this passage, says : " Prof. Trowbridge seems to overlook the advan- 
tage of employing large condensers between the dynamo machines 
and the earth. They would prove of great service in exalting the 
earth potentials at the terminal stations." 


Let, he says, a steamer be provided with a powerful 
dynamo. Connect one terminal of the dynamo with the 
water at the bow of the steamer, and allow a long wire, 
insulated except at its extreme end, to drag over the stern, 
and be buoyed so as not to sink. The current from the 
dynamo will thus pass into the water and spread out over 
a large area, as before explained, saturating, so to speak, 
the water with electricity. Suppose this current be inter- 
rupted by any suitable means, say one hundred times a 
second. Let the approaching steamer be provided with 
a telephone wire, the ends of which dip into the water 
at her bow and stern respectively. On entering the sat- 
urated area the telephone will respond to the interruptions 
of the dynamo by giving out a continuous buzzing sound. 
If now in the dynamo circuit we have a manipulating 
arrangement for breaking up the electric impulses into 
long and short periods, corresponding to the Morse alpha- 
bet, one ship can speak to the other. It is hardly neces- 
sary to add that by providing each steamer with a dynamo 
circuit and a telephone circuit reciprocal correspondence 
could be maintained, it being only necessary for the 
steamer desiring to listen to stop and disconnect the 
dynamo. The success of this method of communicating 
between ships in a fog depends upon the distance between 
the ends of the dynamo circuit and upon the strength of 
the current, or electrical impulses imparted to the water. 

It is probable that a dynamo capable of maintaining 
one hundred incandescent lamps could establish a sufficient 
difference of potential between the water at the bow and 
at the end of a trailing wire, half a mile long, to affect 
a telephone on an approaching ship while yet half a mile 

In a discussion on Prof. Graham Bell's paper, read before 
the American Association for the Advancement of Science, 


1884, Prof. Trowbridge described another plan, using in- 
stead of the telephone circuit a sensitive galvanometer con- 
nected up to a cross-arm of wire, whose ends dip into the 
water at each side of the ship. When one vessel comes 
within the area electrically saturated by another, the galvan- 
ometer will show how the equipotential lines are disturbed, 
and if a map of these lines be carefully traced we can fix 
the position of the approaching ship. He adds : " The 
method could also be applied to saturating the water around 
a rock, and you could take electrical soundings, so to speak, 
and ascertain your position from electrical maps carefully 
made out." 

In a later paper published in the 'Scientific American 
Supplement/ February 21, 1891, Prof. Trowbridge discusses 
the phenomena of induction, electro-magnetic and static, 
as distinguished from leakage or earth conduction, and with 
reference to their employment in wireless telegraphy. 

The hope, he says, that we shall be able to transmit 
messages through the air by electricity without the use 
of connecting wires is supposed by some to indicate its 
realisation at a future day. Let us examine how near we 
are at present to the realisation of this hope. 

He supposes that the chief use of any method by which 
connecting wires could be dispensed with would be at sea 
in a fog. On land for considerable distances it is hardly 
probable that any electrical method could be devised in 
which air or the ether of space could advantageously re- 
place a metallic conductor. The curvature of the earth 
would probably demand a system of frequent repetition, 
which is entirely obviated by the use of a wire. If, how- 
ever, an electrical or magnetic system could be made to work 
through the air even at the distance of a mile, it would 
be of very great use at sea in averting collisions ; for any 
system of signals depending upon the use of fog-horns or 



fog-whistles is apt to mislead on account of the reflection 
of the sound from layers of air of different densities and 
from the surface of the water. The difficulty of ascertain- 
ing the direction of a fog-horn in a thick fog is well known. 
The waves of sound, even if they are carefully directed by 
a trumpet or by parabolic reflectors, diverge so rapidly that 
there is no marked difference in the intensity between a 
position in the direct line and one far to one side. 

The most obvious method of signalling by electricity 
through the air is by electro-magnetic induction. Suppose 

Fig. 8. 

we have a coil of copper wire consisting of many convolu- 
tions, the ends of which are connected with a telephone 
(fig. 8). If we place a similar coil, the ends of which 
are connected to a battery through a key, within a few 
feet of the first and parallel to it, each time the current 
is made and broken in the battery coil instantaneous cur- 
rents are produced by induction in the other coil, as can be 
heard by the clicks in the telephone. 

To illustrate induction at a distance, Prof. Joseph Henry 


placed a coil of wire, 5J feet in diameter, against a door, 
and at a distance of 7 feet another coil of 4 feet diameter. 
When contact was made and broken with a battery of 
eight cells in the first coil, shocks were felt when the 
terminal wires of the second were placed close together 
on the tongue. 

In all such methods the wires or coils which produce 
an electrical disturbance in a neighbouring coil are never 
more than a few feet apart. Now let us suppose that 
a wire is stretched ten or twelve times, to and fro, from 
yard-arm to yard-arm of a steamer's foremast, and con- 
nected at the ends either with a powerful battery or 
dynamo, or with a telephone, as may be required either 
for signalling or for listening. Let an approaching steamer 
have a similar arrangement. If now the current on one 
vessel be interrupted a great number of times per second, a 
musical note will be heard in the telephone of the other 
vessel, and vice versa. The sound will be strongest when 
the two coils are parallel to each other. If, therefore, the 
coils be movable the listener can soon find the position 
of greatest effect, and so fix the direction in which the 
signalling steamer is approaching. 

It may not even be necessary to connect the telephone 
with the coil, for it has been found that if a telephone, 
pure and simple, be held to the ear and pointed towards 
a coil in which a current of electricity is rapidly inter- 
rupted, the makes and breaks will be heard, and this even 
when the wire coil of the telephone is removed, leaving 
only the iron core and the diaphragm. 1 

1 Mr Willoughby Smith was, I believe, the first in recent times to 
observe these effects. See his paper on " Volta-Electric Induction," 
'Jour. Inst. Elec. Eugs.,' vol. xii. p. 457. But exactly similar 
effects, mutatis mutandis, were described by Page in 1837, to which 
he gave the name of Galvanic Music, and which he found to be due 
to the fact that iron when magnetised and demagnetised gave out a 


Nothing could seem simpler than this, but, unfortunately, 
calculation shows that under the best conditions the size of 
the coils would have to be enormous. Prof. Trowbridge 
has computed that to produce an audible note in the tele- 
phone at a distance of half a mile, a coil of ten turns of 
800 feet radius would be necessary ; but it is evident that 
a coil of this size would be out of the question. Instead, 
however, of increasing the size of the coil beyond the 
practical limits of the masts and yard-arms, we could in- 
crease the strength of the current so as to be effective at 
the distance of half a mile; but, again, calculation shows 
that this strength of current would be beyond all practical 
limits of dynamo construction, unless we discover some 
method of tuning, so to speak, two coils so that the elec- 
trical oscillations set up in one may be able to evoke in 
the other sympathetic vibrations. 1 

Since, then, we have little, apparently, to hope for from 
electro - magnetic induction in signalling through a fog, 
cannot we expect something from static induction 1 This 
form of induction can be well illustrated by an early 
experiment of Prof. Henry. An ordinary electrical machine 
was placed in the third storey of his house, and a metal 
plate 4 feet in diameter was suspended from the prime 
conductor. On the first floor or basement, 30 feet below 
in a direct line, was placed a similar plate, well insulated. 
When the upper plate was charged by working the 
machine, the lower plate showed signs of electrification, 
as was evidenced by its effect on the pith-ball electroscope. 2 

sound. De la Rive, in 1843, rightly traced this sound to the slight 
elongation of iron under the magnetic strain a fact which, in its 
turn, was first observed by Joule in 1842. For Page's discovery see 
the 'Magazine of Popular Science,' 1837, p. 237. 

1 Prof. Oliver Lodge is now engaged on this very problem. See 
p. 235, note 2, infra. 

2 See an excellent account of Henry and his work in the New 


The distance to which this electrical influence can be ex- 
tended depends upon the charging power of the machine 
and the dimensions of the plate. If we could erect an 
enormous metal plate on a hill, insulated and powerfully 
charged, it is probable that its electrical influence could be 
felt at the distance of the horizon ; but here, again, the 
question of practical limits conies in as a bar, so that, at the 
present time (February 1891), this method of signalling 
without wires seems as little practicable as the others. 

After following me in this study of Prof. Trowbridge, 
the reader may well begin to despair, for while the learned 
Professor's investigations are extremely interesting, his con- 
clusions are very disappointing. But the darkest hour is 
just before the dawn, and so it is in this case. 


Following the lines suggested by Prof. Trowbridge, Prof. 
Bell carried out some successful experiments, an account of 
which is given in his paper read before the American Asso- 
ciation for the Advancement of Science in 1884. 

" A few years ago," he says, " I made a communication 
on the use of the telephone in tracing equipotential lines 
and surfaces. I will briefly give the chief points of the 
experiment, which was based on experiments made by Prof. 
Adams of King's College, London. Prof. Adams used a 
galvanometer instead of a telephone. 

" In a vessel of water I placed a sheet of paper. At two 
points on that paper were fastened two ordinary sewing 

York 'Electrical Engineer,' January 13, 1892, and succeeding 
numbers, from the pen of his daughter, Mary A. Henry. Abstracts 
of these papers are given in the ' Electrician,' vol. xxviii. pp. 327, 
348, 407, 661. 


needles, which were also connected with an interrupter that 
interrupted the circuit about one hundred times a second. 
Then I had two needles connected with a telephone : one 
needle I fastened on the paper in the water, and the moment 
I placed the other needle in the water I heard a musical 
sound from the telephone. By moving this needle around 
in the water, I would strike a place where there would be no 
sound heard. This would be where the electric tension was 
the same as in the needle ; and by experimenting in the 
water you could trace out with perfect ease an equipotential 
line around one of the poles in the water. 

" It struck me afterwards that this method, which is true 
on the small, is also true on the large scale, and that it 
might afford a solution of a method of communicating elec- 
trical signals between vessels at sea. 

" I made some preliminary experiments in England, and 
succeeded in sending signals across the river Thames in this 
way. On one side were two metal plates placed at a dis- 
tance from each other, and on the other two terminals 
connected with the telephone. A current was established 
in the telephone each time a current was established 
through the galvanic circuit on the opposite side, and if 
that current was rapidly interrupted you would get a musical 

" Urged by Prof. Trowbridge, I made some experiments 
which are of very great value and suggestiveness. The first 
was made on the Potomac river. 

"I had two boats. In one boat we had a Leclanche 
battery of six elements and an interrupter for interrupting 
the current very rapidly. Over the bow of the boat we made 
water connection by a metallic plate, and behind the boat we 
trailed an insulated wire, with a float at the end carrying a 
metallic plate, so as to bring these two terminals about 100 
feet apart. I then took another boat and sailed off. In 



this boat we had the same arrangement, but with a tele- 
phone in the circuit. In the first boat, which was moored, 
I kept a man making signals ; and when my boat was near 
his I would hear those signals very well a musical tone, 
something of this kind : turn, turn, turn. I then rowed my 
boat down the river, and at a distance of a mile and a 
quarter, which was the farthest distance I tried, I could 
still distinguish those signals. 

"It is therefore perfectly practicable for steam-vessels 
with dynamo machines to know of each other's presence in a 
fog when they come, say, within a couple of miles of one 
another, or, perhaps, at a still greater distance. I tried the 
experiment a short time ago in salt water of about 20 fathoms 
in depth. I used then two sailing-boats, and did not get so 
great a distance as on the Potomac. The distance, which 
we estimated by the eye, seemed to be about half a mile ; 
but on the Potomac we took the distance accurately on the 

Later, in urging a practical trial of his method, Prof. Bell 
further said : "Most of the passenger steamships have dynamo 
engines, and are electrically lighted. Suppose, for instance, 
one of them should trail a wire a mile long, or any length, 
which is connected with the dynamo engine and electrically 
charged. The wire would practically have a ground connec- 
tion by trailing in the water. Suppose you attach a telephone 
to the end "on board. Then your dynamo or telephone end 
would be positive, and the other end of the wire trailing 
behind would be negative. All of the water about the ship 
will be positive within a circle whose radius is one-half of 
the length of the wire. All of the water about the trailing 
end will be negative within a circle whose radius is the 
other half of the wire. If your wire is one mile long, there 
is then a large area of water about the ship which is affected 
either positively or negatively by the dynamo engine and the 


electrically charged wire. It will be impossible for any ship 
or object to approach within the water so charged in relation 
to your ship without the telephone telling the whole story 
to the listening ear. Now, if a ship coming in this area also 
has a similar apparatus, the two vessels can communicate 
with each other by their telephones. If they are enveloped 
in a fog, they can keep out of each other's way. The ship 
having the telephone can detect other ships in its track, and 
keep out of the way in a fog or storm. The matter is so 
simple that I hope our ocean steamships will experiment 
with it." l 


Prof. Dolbear of Tuft's College, Boston, was also, about 
the same time as Graham Bell, engaged on the problem of a 
wireless telegraph, and produced a very simple and workable 
(at least for short distances) apparatus, which he patented 
in the United States, and of which he gave a description at 
a meeting of the American Association for the Advancement 
of Science in 1883. I take the following account from his 
specification as published in the ' Scientific American Sup- 
plement/ December 11, 1886 : 

" In the diagram, A represents one place (say Tuft's College) 
and B a distant place (say my residence). 

" c is a wire leading into the ground at A, and D a wire 
leading into the ground at B. 

" G is an induction coil, having in the primary circuit a 
microphone transmitter T, and a battery /', which has a 
number of cells sufficient to establish in the wire c, which 
is connected with one terminal of the secondary coil, an 
electro-motive force of, say, 100 volts. The battery is so 
1 Public Opinion, January 31, 1886. 



connected that it not only furnishes the current for the 
primary circuit, but also charges or electrifies the secondary 
coil and its terminals c and H'. 1 

" Now, if words be spoken in proximity to transmitter T, 
the vibration of its diaphragm will disturb the electric con- 
dition of the coil G, and thereby vary the potential of the 
ground at A, and the variations of the potential at A will 
cause corresponding variations of the potential of the ground 
at B, and the receiver R will reproduce the words spoken 
in proximity to the transmitter, as if the wires c D were in 
contact, or connected by a third wire. 

Fig. 9. 

" There are various well-known ways of electrifying the 
wire c to a positive potential far in excess of 100 volts, and 
the wire D to a negative potential far in excess of 100 volts. 

" In the diagram, H H' H 2 represent condensers, the con- 
denser H' being properly charged to give the desired effect. 
The condensers H and H 2 are not essential, but are of some 
benefit ; nor is the condenser H' essential when the second- 
ary coil is otherwise charged. I prefer to charge all these 
condensers, as it is of prime importance to' keep the grounds 
of wires c and D oppositely electrified, and while, as is 

1 The diagram, which we have carefully copied, does not show how 
this is done, but the practical reader will easily supply the necessary 


obvious, this may be done by either the batteries or the 
condensers, I prefer to use both." 

Prof. Dolbear states that communication by this method 
is quite practicable at a distance of half a mile at least, but 
its possible range he had not yet determined. 

In the article from which I am quoting the author gives 
some additional particulars which are worth repeating. 
" My first results," he says, " were obtained with a large 
magneto-electric machine with one terminal grounded through 
a Morse key, the other terminal out in free air and only a 
foot or two long ; the receiver having one terminal grounded, 
the other held in the hand while the body was insulated, 
the distance between grounds being about 60 feet. After- 
ward, much louder and better effects were obtained by using 
an induction coil having an automatic break and with a 
Morse key in the primary circuit, one terminal of the 
secondary grounded, the other in free air, or in a condenser 
of considerable capacity, the latter having an air discharge 
of fine points at its opposite terminal. At times I have 
employed a gilt kite carrying a fine wire from the secondary 
coil. The discharges then are apparently nearly as strong 
as if there was an ordinary circuit. 

" The idea is to cause a series of electrical discharges into 
the earth at a given place without discharging into the earth 
the other terminal of the battery or induction coil a feat 
which I have been told so many, many times was impossible, 
but which certainly can be done. An induction coil isn't 
amenable to Ohm's law always ! Suppose that at one place 
there be apparatus for discharging the positive pole of the 
induction coil into the ground, say 100 times per second, 
then the ground will be raised to a certain potential 100 
times per second. At another point let a similar apparatus 
discharge the negative pole 100 times per second ; then 
between these two places there will be a greater difference 


of potential than in other directions, and a series of earth- 
currents, 100 per second, will flow from the one to the other. 
Any sensitive electrical device, a galvanometer or telephone, 
will be disturbed at the latter station by these currents, and 
any intermittence of them, as can be brought about by a 
Morse key in the first place, will be seen or heard in the 
second place. The stronger the discharges that can be thus 
produced, the stronger will the earth-currents be of course, 
and an insulated tin roof is an excellent terminal for such a 
purpose. I have generally used my static telephone receiver 
in my experiments, though the magneto will answer. 

" I am still at work upon this method of communication, 
to perfect it. I shall soon know better its limits on both 
land and water than I do now. It is adapted to telegraphing 
between vessels at sea. 

"Some very interesting results were obtained when the 
static receiver with one terminal was employed. A person 
standing upon the ground at a distance from the discharging 
point could hear nothing; but very little, standing upon 
ordinary stones, as granite blocks or steps ; but standing on 
asphalt concrete, the sounds were loud enough to hear with 
the telephone at some distance from the ear. By grounding 
the one terminal of the induction coil to the gas or water 
pipes, leaving the other end free, telegraph signals can be 
heard in any part of a big building and its neighbourhood 
without any connection whatever, provided the person be 
well insulated." 

When we come to speak of the Marconi system, we shall 
see how near Dolbear got to that great discovery in his 
acute observation of the heightened effects obtained by pro- 
jecting into free air the ungrounded terminal wires of the 
sending and receiving apparatus. 1 His use of condensers 

1 Compare his sending apparatus with that of Marconi, fig. 41, p. 
208, infra. 

T. A. EDISON. 103 

and gilt kites " carrying fine wire " was another step in the 
direction of Marconi ; and had he used thick instead of fine 
wire he would have obtained even better results. However, 
Hertz had not yet come to make clear the way which 
Dolbear saw but as in a glass darkly ! l 

T. A. EDISON 1885. 

Electric communication with trains in motion, like com- 
munication with ships at sea and with lighthouses, has 
long been a favourite problem with electrical engineers : 
indeed it is much the older of the two, and dates back to 
the first days of electric telegraphy. 

In 1838 Edward Davy, the rival of Cooke and Wheat- 
stone, proposed such a system. In a lecture on " Electric 
Telegraphy," delivered in London during the summer of 
1838, he says: 

" I have a few words to say upon another application 
of electricity namely, the purposes it will answer upon a 
railway, for giving notices of trains, of accidents, and stop- 
pages. The numerous accidents which have occurred on 
railways seem to call for some remedy of the kind ; and 
when future improvements shall have augmented the speed 
of travelling to a velocity which cannot at present be 
deemed safe, then every aid which science can afford must 
be called in to promote this object. Now, there is a con- 
trivance, secured by patent, by which, at every station along 
the railway line, it may be seen by mere inspection of a dial 
what is the exact situation of the engines running either 
towards or from the station, and at what speed they are 

1 Mr C. Dolbear, a son of the Professor, is understood to be engaged 
on some form of wireless telegraph which is reported to have worked 
successfully over a distance of 500 yards. Details are wanting. 


travelling. Every time the engine passes a milestone, the 
pointer on the dial moves forward to the next figure, a 
sound or alarm accompanying each movement. 

" Not only this, but if two engines are approaching each 
other, by any casualty, on the same rails, then, at a distance 
of a mile or two, a timely notice can be given in each 
engine by a sound or alarm, from which the engineer 
would be apprised to slacken the speed ; or, if the engineer 
be asleep or intoxicated, the same action might turn off the 
steam, independently of his attention, and thus prevent an 
accident." 1 

In 1842 William Fothergill Cooke published his 'Tele- 
graphic Railways,' descriptive of a crude system of train 
signals, which was tried, in 1843, in the Queen Street 
tunnel, Glasgow, and in the Clay Cross tunnel, Derby ; 
and, on a more extensive scale, in 1844, on the Great 
Eastern Railway, between Norwich and Yarmouth. 

Dujardin in 1845, Brett and Little in 1847, Edwin Clark 
in 1:854, Bonelli in 1855, and many others, proposed various 
systems of train signalling; but as they are all based on 
ordinary telegraphic principles and require connecting wires, 
they do not specially concern us in this history. 

Mr A. C. Brown, an officer of the Eastern Telegraph 
Company, claims to have been the first to suggest, in 1881, 
the method of induction for communicating with moving 
trains. In a letter published in the 'Electrician,' March 
21, 1885, he says: 

"My object was chiefly to provide an efficient means of 
fog-signalling, by enabling the signalman to communicate 
directly with the drivers or guards. I proposed to run a 

1 See the writer's 'History of Electric Telegraphy,' 1884, p. 407. 
The most perfect block system of the present day does not do any- 
thing like this. Davy's plan was actually patented by Henry Pinkus ! 
See his patent specification, No. 8644, of September 24, 1840. 

T. A. EDISON. 105 

wire along the permanent way, parallel with the rails, and 
to wind a coil of wire round the engine, or carriage to be 
communicated with, in such a way as to get as long a length 
of wire parallel to, and as near to, the line-wire as possible, 
so as to be well exposed to the inductive action thereof. I 
then proposed to place in the signal-boxes a battery, sig- 
nalling key, and rapid make-and-break instrument, or buzzer, 
and to thereby signal to the train, using a telephone in 
circuit with the train-coil as a receiver. By using an ordin- 
ary carbon transmitter in the line-wire, I also found it quite 
practicable to speak verbally to the train, so as to be dis- 
tinctly heard in the telephone. 

" This design was embodied in a paper which, in the year 

1881, I laid before the managing director of the United 
Telephone Company, but want of time and opportunity 
prevented its being put into practice. It was experimentally 
tried at that time, using wire coils, properly proportioned 
in length, resistance, and distance apart to the conditions 
that would be obtained in practice. It has since been 
simplified and arranged to produce both visible and audible 
signals on the engine or car by induction from a No. 8 iron 
line-wire across a space of 6 inches, with a current of only 
one quarter ampere, or such as can easily be produced by 
the ordinary Daniell batteries used in railway work." * 

In 1883 Mr Willoughby Smith threw out a similar 
suggestion towards the end of his paper on "Voltaic-Electric 
Induction," read before the Institution of Electrical En- 
gineers, November 8 of that year : 2 

" Telegraph engineers," he says, " have done much 
towards accomplishing the successful working of our present 
railway system, but still there is much scope for improve- 

1 For another proposal of Mr Brown, see p. 176, infra. 

- Compare also his remarks, 'Jour. Inst. Elec. Engs.,' March 23, 

1882, p. 144. 


ments in the signalling arrangements. In foggy weather 
the system now adopted is comparatively useless, and 
recourse has to be had at such times to the dangerous and 
somewhat clumsy method of signalling by means of de- 
tonating charges placed . upon the rails. 

" Now, it has occurred to me that Yolta-Electric induction 
might be employed with advantage in various ways for 
signalling purposes. For example, one or more spirals 
could be fixed between the rails at any convenient distance 
from the signalling station, so that, when necessary, inter- 
mittent currents could be sent through the spirals; and 
another spiral could be fixed beneath the engine, or guard's 
van, and connected to one or more telephones placed near 
those in charge of the train. Then, as the train passed 
over the fixed spiral, the sound given out by the transmitter 
would be loudly reproduced by the telephone, and indicate 
by its character the signal intended. 

" One of my experiments in this direction will perhaps 
better illustrate my meaning. The large spiral was con- 
nected in circuit with twelve Leclanche cells and the two 
make-and-break transmitters before described. They were 
so connected that either transmitter could be switched into 
circuit when required, and this I considered the signalling 
station. The small spiral was so arranged that it passed in 
front of the large one at the distance of 8 inches, and at a 
speed of twenty-eight miles per hour. The terminals of the 
small spiral were connected to a telephone fixed in a distant 
room, the result being that the sound produced from either 
transmitter could be clearly heard and recognised every time 
the spirals passed each other. With a knowledge of this 
fact I think it will be readily understood how a cheap and 
efficient adjunct to the present system of railway signalling 
could be obtained by such means as I have ventured to 
bring to your notice this evening." 

T. A. EDISON. 107 

In 1885 Mr T. A. Edison had his attention directed to 
the subject, and with his usual thoroughness he soon pro- 
duced a very complete system, with the assistance of 
Messrs Gilliland, Phelps, and W. Smith to the last- 
named of whom the original idea is said to be due. 1 

The inevitable avant-coureur appeared in the technical 
journals of the period, and as it is delightfully character- 
istic of the great magician of Menlo Park, we venture to 
reproduce it here : " Mr Edison's latest invention, an 
arrangement to telegraph from moving trains, is thus 
described by a recent visitor to his laboratory : Overhead 
was a board eight inches wide, suspended from the ceiling 
by ropes fastened to one of its edges. One side of it was 
covered with tinfoil, and was facing toward a wall 20 feet 
distant. That,' said Mr Edison, ' is my railroad signal ; 
I make electricity jump 35 feet, and carry a message. 
This is something quite new ; no induction has ever been 
known that extended over 3 or 4 or 5 feet. This inven- 
tion uses what is called static electricity, and it makes 
every running train of cars a telegraph station, accessible to 
every other telegraph station on the road. Messages may 
be sent to and from conductors, and to and from passengers. 
It requires no extra wire, either under the cars or at the 
side of the cars, but uses the ordinary telegraph just as it 
is put up at the side of the track. This white board is a 
receiver and transmitter. A board like it is to be fastened 
lengthwise along the peak of each car, where it will be 
out of the way and will not be a blemish. When the 
train is telegraphed to, the message jumps from the wire 

1 Although I have not seen any acknowledgment of their indebted- 
ness, Mr Edison and his coadjutors can hardly have been ignorant of 
Mr Willoughby Smith's very clear proposal, of which their contriv- 
ance is but the practical realisation. Given the idea, the rest was 
easy enough. 



on the side of the track 
and alights on this board, 
and is conveyed to the ap- 
paratus in the train below. 
It works beautifully from 
those wires strung yonder. 
I was as much astonished 
as anybody at finding out 
what could be done. It 
costs very little, moreover, 
as 300 miles of road can be 
equipped for 1000 dols.'" 

This contrivance was 
patented in England on 
June 22, 1885, in the 
joint names of T. A. Edison 
and E. T. Gilliland, and 
is fully described in their 
specification, No. 7583, of 
which the following is an 
abstract : 

The object of the inven- 
tion is to produce apparatus 
for telegraphing between 
moving trains, or between 
trains and stations, by in- 
duction and without the use 
of connecting wires. The 
accompanying drawing (fig. 
10) represents a station and 
portions of two trains with 
the apparatus for signal- 
ling. The carriage to be 
used as the signal office 

T. A. EDISON. 109 

has placed upon its top or side, or upon each side, a 
metallic condensing surface running the entire length of 
the car. This consists of a strip a of metal, say a foot 
wide, well insulated by blocks of glass ; or it may be thin 
sheet metal or metallic foil secured to canvas, and similarly 
insulated from the body of the car. To increase the total 
condensing surface, all the carriages of the train are prefer- 
ably provided with such strips, which are connected electri- 
cally by suitable couplings c when the train is made up. 
A wire 1 is connected with this condensing surface, and 
extends through the apparatus to the carriage-truck so as 
to form an earth connection through the wheels and the 
rails upon which they travel. The apparatus just men- 
tioned consists of an induction coil B, the secondary wire 
of which is of extremely high resistance, and is in the 
circuit of wire 1, in which is also connected a telephone 
c of high resistance. This is preferably an electro-moto- 
graph telephone, the chalk cylinder of which is kept in 
constant rotation by a suitable motor, electrical or mechani- 
cal; but a magneto-electric or other suitable form of tele- 
phone may be employed. 

In the primary circuit of the induction coil B are a local 
battery d and a revolving circuit -breaker D. This is a 
wheel having its surface broken by cross strips of insula- 
tion ; upon it rests a spring, the circuit being through the 
spring to the spindle of the wheel. This wheel is kept in 
rapid motion by a suitable motor, electrical or mechanical, 
the current vibrations produced by it being a great number 
per second and audible in the telephone receiver. 

The circuit -breaker is shunted by a back point key E, 
which, normally, short - circuits it and prevents it from 
affecting the induction coil. A switch F short-circuits the 
secondary wire of the induction coil when receiving, and is 
opened in transmitting. 


. The ordinary telegraph wires 2, 3, 4, 5, run on poles at 
the side of the track, and, grounded at their ends, are util- 
ised collectively for conveying the signals. They form the 
other surface of the condenser (the strips on the carriages 
forming one surface), while the intervening body of air is 
the dielectric. 

In signalling between trains, signals are transmitted by 
working the key E in the office upon one train. This 
causes static impulses at the condensing surface upon the 
carriages which affect the telegraph wires. These in turn 
affect the condensing surface upon the carriages of the other 
train, and cause impulses which are audible in the tele- 

At each signalling station i there is erected between the 
telegraph wires a large metallic condensing surface K (fig. 
11). This may be attached to a frame supported from the 
telegraph poles or from separate poles. A wire 6 runs from 
this condensing surface to the station, where it is connected 
to ground through the same character of transmitting and 
receiving apparatus already described for the carriages. 

Instead of using this condensing surface outside of the 
station, a separate wire (7, 8, 9, 10, fig. 10) may be at- 
tached to each telegraph wire (or to each of as many as it is 
desired to utilise) and run into the station, where it is con- 
nected to one side of a condenser L, of ordinary form. The 
other sides of the several condensers L are connected to- 
gether, and by a common wire 1 1 to ground through the 
transmitting and receiving apparatus. 

The telegraph wires are kept constantly closed for trans- 
mitting the induction impulses by shunting the regular 
Morse keys M by condensers N. These condensers do not 
interfere with the carrying on of the ordinary telegraphing 
over such wires, at the same time that they form constantly 
closed paths for the induction impulses independent of the 



working of the ordinary Morse keys. The ordinary Morse 
relay and sounder are shown at o and p respectively. 

The stations being connected for railway signalling induc- 
tively with the line wires the same as are the trains, signals 
are received and transmitted by a station the same as by a 

Fig. 11. 

train. The trains and stations are connected inductively 
with the line wires in multiple arc, so to speak, signals be- 
ing transmitted by keys, circuit breakers, and induction 
coils, and received by telephones. 

The signalling is conducted by Morse characters, or 


by numerical signals in accordance with an established 

Speaking of the potentialities of his system, Edison, early 
in 1886, said: "The outcome is easy to predict. Special 
correspondents may, in the future, wire their despatches 
straight to the offices of their journals. Eailway business 
will be expedited to a degree undreamt of as things are, 
and the risk of accidents will be largely diminished by 
knowing the position of trains and the cause of delay or 
accident, if any, at every stage, of their route. Ships at 
sea, many miles apart, will be able to communicate by 
means of balloon-kites, soaring several hundred feet above 
their decks. Messages can be passed from ship to ship, and 
a casualty like that of the Oregon telegraphed to the nearest 
land. In times of war the applications of the air-telegraph 
system are obvious. Kegions now remote from telegraphs 
could be brought within the civilised circle by means of 
mountain or forest stations equipped with the new apparatus. 
Even the man of business of the future may communicate 
with his employes as he journeys to and from his office, and 
save time or make money while he is literally on the wing. 
Not the least interesting feature of this new departure in 
telegraphy is the thought that, in its turn, it may be the 
harbinger of still more wondrous modifications of the 
system which has girdled the earth in a space inconceivably 
short when compared with that imagined by the fairy 
romancer who created Puck." l 

The Edison system was first put in operation at Staten 
Island, U.S.; then, a few months later, on the Chicago, 
Milwaukee, and St Paul line; and by October 1887 it was 
established on the Lehigh Valley Eailroad, as related in the 
following paragraphs : 

"The success of what is called ' railway train telegraphy ' 
1 Weekly Irish Times, April 10, 1886, 

T. A. EDISON. 113 

is now assured, and October 6, 1887, will be a red-letter day 
in the history of the electric telegraph. On that day a 
special train left Jersey City with about 230 members of the 
Electric Club and guests of the Consolidated Eailway Tele- 
graph Company, in order to witness the working of the 
system on the Lehigh Valley Railroad. The system is a 
combination of the best features of the inventions of Edison, 
Gilliland, Phelps, and Smith, and although the speed often 
reached the rate of about sixty miles an hour, messages were 
sent from and received on the train without difficulty, 
although the current or the ' induction ' had to jump from 
the train to the line wires, a distance of 25 feet. About 
four hundred messages were sent as the train ran from Perth 
Junction to Easton, amongst them a rather long one from 
Colonel Gouraud to Mr John Fender in London." l 

" One of the most interesting triumphs of invention has 
been achieved on the Lehigh Valley Railroad during the 
snowstorms of the past winter in the United States. This 
railway for some months has been using on its trains the 
system of communication known as train telegraphy. The 
wire, being of steel, and stretched upon stout poles only 
15 or 16 feet high, withstood the fury of the storm. The 
consequence was that all snowed-up trains on the Lehigh 
Valley Railroad kept up constant communication with the 
terminus of the road, could define exactly their position, and, 
in short, had all the advantages of perfect telegraphic com- 
munication." 2 

Soon after this the system fell into desuetude, and for a 
very simple reason nobody wanted it. Whatever " special 
correspondents " and " the man of business " in the future 
may require, they, apparently, prefer nowadays to be free 
from telegrams of all sorts "while on the wing." 

1 Public Opinion, November 4, 1887. 

2 Ibid., April 13, 1888. 



W. F. MELHUISH 1890. 

We have seen (p. 39 ante) that the want of some form of 
wireless telegraph was peculiarly felt at a very early date in 
India, where the rivers are many and wide, and where for 
various reasons cables are liable to frequent breakage, caus- 
ing interruptions which are as likely as not to be of long 
duration, owing to the great rush of waters and the flooding 
of banks. 

I have already given some account of Dr O'Shaughnessy's 
experiments in this direction. It is all too short, but, 
unfortunately, it is all that I have been able to gather. 

About the year 1858 Mr Blissett, a superintendent in 
the Indian Telegraph Department, resumed the inquiry, and 
obtained a fair measure of success by employing land-lines 
of considerable length on each bank of the river. In 1876 
Mr Schwendler, then electrician, made some trials across the 
Hooghly at Barrackpore, near Calcutta, which were continued 
at intervals by his successor, the late Mr W. P. Johnston. 

On September 9, 1879, this gentleman tried the following 
arrangement for signalling across the water of a canal. Fig. 
1 2 shows the connections : 

E = 10 Bunsen's cells joined in series ; 

K, a needle instrument having a resistance of 1 ohm ; also 
a telephone having a resistance of 4*25 ohms ; 

w = a resistance of 1"! . 

, I his arrangement exactly balanced 

,... > the natural current through the 

e tour Mmotto cells . . 

, , receiving instrument, 
joined parallel J 

A, B, c, D were copper plates, 8 feet 8 inches by 4 feet 
4 inches by 1-1 6th inch thick, buried on the banks of the 
canal. B was buried 15 yards distant from A, and D the 
same distance from c. All the plates were parallel to the 



canal. The resistance between A and B was 7*5 ohms, and 
that between c and D was the same. Under these conditions 


o > 


Fig. 12. 

both tlie needle instrument and the telephone gave distinct 
and readable signals. 

After several days of experiment with another method 

Bare wtr* 7 Mil* under Water 

Fig. 13. 

(fig. 13), using a single bare 600 Ib. per mile galvanised 
wire, the following results were obtained : 

E = 15 Bunsen's cells in series ; 

R, a polarised Siemens relay of 21 ohms resistance; 


e - 4 Minottos joined parallel ) Balanced the natural 

w = 10 ohms ) current. 

The signals received were quite regular and safe ; the 
tongue of a relay worked an ordinary sounder in local 
circuit, and no difficulty was experienced in balancing the 
natural current through the relay. 

A trial with bare wire for a distance of one and a half 
mile was not successful. Indeed, as it appeared that in 
order to obtain signals the battery power must be increased 
as the square of the distance, the limit of signalling through 
a bare wire under water is very soon reached. 

Subsequently, three miles of the same wire, but partially 
insulated by being passed through a mixture of pitch and 
tar, answered perfectly for the hour that the instruments 
were in circuit. 

At various times during the year 1888 Mr Johnston 
carried out many experiments across canals and the river 
Hooghly, and as the result of these and other careful in- 
vestigations he was led to the following conclusions : 

1. That up to one and a half mile it is perfectly easy to 

signal through a bare wire under water. 

2. That for greater distances, judging from experiments, 

practical signalling is not possible. 

Tn April 1889 Mr Johnston died, and the duties of elec- 
trician were entrusted to Mr Melhuish, who immediately 
took up the inquiry, and in the end produced some very 
considerable results, for which, I believe, the Government 
of India gave him the handsome honorarium of 5000 

The results of his investigations are embodied in a 
paper which was read before the Institution of Electrical 
Engineers on April 10, 1890 : 

" Having studied," he says, " the recorded labours of my 
predecessor, and learnt that by pursuing the same lines 

W. F. MELHUISH. 117 

it was hopeless to expect to be able to signal through a 
bare wire across a river that had a greater breadth than 
one and a half mile, I resolved to change the class of 
signalling apparatus and to continue the experiment. Dis- 
carding continuous steady currents and polarised receiving 
relays, I adopted Cardew's vibrating sounder, and the 
sequel will show how completely successful the change 
of instruments proved to be. I began from the beginning, 
and tried to signal across a water-way without a metallic 
conductor by laying down two earth-plates on each of its 
opposite banks. Readable signals having been exchanged, 
the distance separating each pair of plates was varied, 
with the view of ascertaining how close the plates might 
be brought together, the signals remaining still readable. 
Eeadable signals were exchanged when the distance separ- 
ating the plates was equal to the breadth of the river, 
reading becoming more difficult as the plates were made 
to approach each other, and clearer and more distinct as 
the distance between the plates was made to exceed the 
breadth of the river. I learnt from these experiments 
that in order to obtain signals of sufficient distinctness 
for the practical purpose of transmitting messages, it would 
be necessary to construct a line on each bank of a river 
much longer than the breadth of the river; and as the 
rivers along the coasts in India are extremely wide, I 
became impressed with the impracticable character of such 
an undertaking, and decided to strike out a new line. 

" This new line was the laying of two bare uninsulated 
iron wires across the water-way parallel to each other, 
and separated by a certain distance, the ends on each 
bank being looped together by means of an insulated 
conductor. Hence, though much of the circuit was laid 
under water, it was nevertheless a continuous' metallic 
circuit. Beginning first with a complete square, by laying 


the wires as many yards apart as the river was wide, 
signals were instantly exchanged that were incomparably 
louder than those that were exchanged when the same 
area was bounded by four earth -plates. The length of 
each of the two wires under water was next gradually 
increased to 740 yards, and the distance separating them 
gradually diminished to 35 yards, the strength of the 
signals diminishing proportionately, and ceasing to be 
readable when the wires were further approached. The 
conclusion arrived at from these experiments was that, 
for the practical and useful purpose of signalling messages 
across a broad river, in the absence of an insulated cable, 
a complete metallic circuit was at least desirable. Acting 
on this conclusion, it was sought to apply it practically, 
and the following experiment was carried out: At a dis- 
tance of fifteen miles west of Calcutta a cable is laid 
across the river Hooghly, which at this point is 900 yards 
wide. The iron guards of this cable were employed to 
form one of the metallic conductors, and at a distance 
of 450 yards down-stream a single wire, weighing 900 
Ib. per mile, was laid across the river to form the second 
metallic conductor, insulated land-lines having been run 
up to loop the two parallel conductors together. The 
experiment was quite a success, the signals being readable 
without difficulty. 

"An experiment was next made on a defective cable 
across Channel Creek, at the mouth of the river Hooghly. 
This creek is crossed by two cables laid in the same trench ; 
the length of each is 3000 yards, and one of them had 
been completely parted by a steamer's anchor. Several 
attempts were made to signal across by using the guards 
of one of the cables as a lead, and the guards of the other 
as a return wire, but the efforts proved unsuccessful owing 
to the too close proximity of the cables. For every crossing 

W. F. MELHUISH. 119 

there is a certain minimum distance apart at which the 
cables must be laid, and if this minimum, which depends 
on the breadth of the river, be exceeded, an absolute short- 
circuit becomes established. But although it was not 
possible here to signal through the iron guards, the most 
perfect signals were passed through the two conductors 
when they were formed into a loop, notwithstanding the 
fact that the two ends of the broken conductor were ex- 
posed in the sea and were lying at a considerable distance 
apart. An experiment was now made in order to ascertain 
what chance there might be in the future of signalling 
across the two conductors, should an accident occur to the 
good cable. Accordingly, the conductor of the good cable 
was disconnected in the cable-house from the signalling ap- 
paratus and placed upon the ground, when the signals, 
though greatly diminished in volume, still continued to be 
distinctly readable. It may, therefore, be reasonably in- 
ferred that should the good cable suffer a similar fate to 
that of the defective cable, communication can, by means of 
Cardew's sounders, be kept up by looping the ruptured 
conductors until arrangements can be made for laying a new 
cable or repairing the defective ones. 

" It will probably suffice if from the succeeding experi- 
ments that were made to test the efficiency of the vibrating 
sounder in the case of conductors breaking down at river 
crossings I select the following three, exhibiting as they do 
progressive evidence of the value of this signalling instru- 
ment, and culminating in establishing it beyond dispute as 
one that can be relied on for carrying on independent com- 
munication through the iron guards of cables while the 
insulated copper conductors form parts of other circuits. 

"Experiment No. 1. The local line from the Central 
Office, Calcutta, to Garden Eeach is about four miles in 
length, and at about midway the wire spans a small river. 


Vibrating sounders having been put in circuit at each 
end of this line, the wire where it crosses the river was 
taken down and laid along the bed of the water-way. Sig- 
nals were loud and clear at both ends. 

" From the success of this experiment it may be inferred 
that on any ordinary line, should the wire from accidental 
causes come off the insulator and make earth by touching 
the bracket, standard, or ground, or should the wire break 
and both ends of it be lying on the ground or in a water- 
course, communication could still be maintained by means 
of the vibrating sounders. 

" Experiment No. 2. The line wire which connects the 
town of Chandernagore with Barrackpore is about ten and a 
half miles long, 900 yards of which consist of a cable laid 
across the river Hooghly. Vibrating sounders having been 
joined up in the telegraph offices at Barrackpore and Chan- 
dernagore, the insulated conductor of the cable was thrown 
out of circuit, and the line wire on each side of the river 
was joined to the iron guards of the cable. Thus for a 
length of half a mile out of ten and a half miles the con- 
ductor was wholly under water, yet it was found quite 
feasible to transmit messages between the two offices. 

" From the success of this experiment it may be reason- 
ably inferred that in the case of certain cable crossings, 
where the rivers are not too wide, should the copper con- 
ductor of the cable make dead earth, or become insulated 
by parting, communication could still be kept up between 
the two offices on either side. 

"Experiment No. 3. The terminus of the Northern 
Bengal State Eailway at Sara is separated from that of the 
Eastern Bengal State Eailway at Damukdia by the river 
Ganges. The opposite banks of the river in this locality 
are connected by two independent cable crossings. The 
length of one of these crossings is one mile 610 yards, and 

W. F. MELHUISH. 121 

of the other four miles. The distance which separates the 
two cable-houses on the Damukdia side is three miles 1584 
yards, and on the Sara side the cable-houses are only one 
mile 211 yards apart, giving a mean lateral distance in 
alignment of two miles 880 yards. The two cable-houses 
on each bank of the river have an insulated connecting land- 

" The connecting land-lines having been joined to the iron 
guards of the cables, two vibrating sounders were placed in 
circuit, one on each side of the river, when signals so strong 
were transmitted across that it was not difficult to read 
them at a distance of 6 feet away from the receiving tele- 

" From the marked success of this experiment it may be 
inferred that at all river cable crossings where the cables 
are laid in separate alignments (and the farther apart the 
better), should the cables become interrupted, communica- 
tion may still be maintained from bank to bank by using 
vibrating sounders, thus avoiding the delay, inconvenience, 
and cost of a boat service. 

" It should also be remembered in the case of such a par- 
allel cable crossing that, besides the circuits afforded by the 
copper conductors when these are in working order, there 
is always an additional local circuit available by means of 
the iron guards between the opposite cable-houses, and that 
this circuit could be used by means of the vibrating sounder 
as a talking circuit, in cases of necessity, without interrupt- 
ing through working on either of the cables. 

" It is desirable in circumstances similar to these to re- 
duce all the resistance external to the actual connecting 
lines to as small a quantity as possible, and therefore, when 
messages are being transmitted, the telephone at the sending 
end should be removed from the circuit, as also should the 
vibrator from the receiving end. To effect this twofold 



purpose a special form of signalling key is requisite, and 
should be used. The action of this key, together with the 

Fig. 14. 

complete set of connections for a parallel cable crossing, is 
shown in fig. 14." x 

C. A. STEVENSON 1892. 

Early in 1892 Mr Stevenson threw out the suggestion 
that telegraphic communication could be established be- 
tween ship and ship by means of coils of wire. 2 

In his paper read before the Royal Society of Edinburgh, 
Marclvl9, 1894, he refers to this suggestion, and says that 
a trial of his method on a large scale had recently been 
made with a view of ultimately employing it for effecting 
communication between Muckle Flugga, in the Shetlands, 
and the mainland. 

As regards the efficacy of the principle, the inductive 
effect of one spiral on another at a distance has long been 

1 Melhuish's plan is the practical realisation of the early proposals 
of Highton and Bering. See pp. 40, 48, ante. 

2 Engineer, March 24, 1892. 


known ; but hitherto, even with a very strong battery, it 
was impossible to bridge a greater distance than 100 yards, 
which for practical purposes was, of course, useless. 

It is evident that if two coils are placed so that their 
axes are coincident, their planes being parallel, or if they 
be placed so that their planes are in the same plane, they 
will be in good positions for electric currents sent in one 
to be apparent by induction in the other. 

For a small diameter, and where the electrical energy is 
small and the number of turns small, the first position is 
best ; but where the energy is great and the number of 
turns great in fact, when it is wished to carry the induction 
to many times the diameter of the coils then it will be 
found that it is better to let the two coils be in the same 
plane, as when the axes are coincident, and the coils a 
greater distance apart in comparison with the diameter, the 
difference of distance from one side of the coil, say top of 
primary coil to top and bottom of secondary, becomes 
almost a vanishing quantity ; whereas, when the coils are 
lying on their side in the same plane, the difference of 
distance from back of primary to back of secondary, and 
from front of primary to front of secondary, does not fall 
off so fast, and consequently is more efficacious. Besides, 
it becomes impracticable to erect coils of large diameter 
with their planes vertical, but it is easy to lay them on 
their sides. 

Mr Stevenson made a large number of laboratory 
experiments on the interaction of coils, with the view of 
calculating the number of wires, the diameter of coils, the 
number of amperes, and the resistance of the coils that 
would be necessary to communicate with Muckle Flugga ; 
and, after a careful investigation, it was evident the gap of 
800 yards could, with certainty, be bridged by a current of 
one ampere with nine turns of post-office wire in each coil, 


the coils being 200 yards in diameter, and with two good 
telephones on the hearing coil. 

Two coils, on telegraph-poles and insulators, were erected 
at Murrayfield, one coil being on the farm of Damhead and 
the other on the farm at Saughton, and as nearly as was 
possible on a similar scale, and the coils of similar shape to 
what was wished at Muckle Flugga. On erecting the coils, 
communication was found impossible, owing to the induc- 
tion currents from the lines from Edinburgh to Glasgow, the 
messages in those lines being quite easily read, although the 
coils were entirely insulated and were not earthed. The 
phonophore which the North British Railway Company have 
on their lines kept up nearly a constant musical sound, 
which entirely prevented observations. On getting the 
phonophore stopped, it was found that 100 dry cells, with 1*2 
ohms resistance each and 1*4 volts, gave good results, the 
observations being read with great ease in the secondary by 
means of two telephones. The cells were reduced in 
number down to fifteen, and messages could still easily be 
sent, the resistance of the primary being 24 ohms and the 
secondary no less than 260 ohms. If the circuit had been 
of good iron, with soldered joints and well earthed, the 
resistance would have been only 60 ohms. The induced 
current generated in the secondary would therefore be in the 
ratio of 480 p 520] to 210, or, allowing for the resistance 
in the two telephones, we get practically only half the 
current we would have got if the line had been a permanent 
in place of a temporary one. 

A trial was made of the parallel-wire system : l with 20 
cells the sound was not heard, and with 100 cells it was 
heard as a mere scratch in comparison with the sound with 
the coil system with only 15 cells. A trial was made with 

f l I.e., Mr Preece's method, to be presently described. See p. 154 
et seq., infra. 


the phonophore : the coils worked with 10 cells with perfect 
ease, and a message was received with only 5 cells. Speech 
by means of Deckert's transmitter was just possible, but it 
is believed that if the hearing circuit had been of less resist- 
ance it would have been easy to hear. 

" It is difficult," says Mr Stevenson, " to understand how 
this system of coils, in opposition to the parallel-wire system, 
has not been recognised as the best ; for assume that, with 
the arrangement we had, we heard equally with 100 cells by 
both systems, both having the same base (200 yards), then, 
by simply doubling the number of turns of wire on the 
primary and using thick wire, the effect would have been 
practically doubled, whereas by the parallel-wire system 
there is nothing for it but to increase the battery power. 
The difficulty of the current is thus removed by using a 
number of turns of wire. It must always be borne in mind 
that the effect is the result of simply increasing the diameter, 
keeping current and resistance the same. The larger the 
diameter the better. What is wanted is to get induction at 
a great distance from a certain given base with a small 
battery power, and the laboratory experiments and the trials 
in the field show that the way to overcome the difficulty of 
the current is by using a number of turns of wire. The 
secret of success is to apportion the resistance of primary 
and secondary, and the number of turns on each, to a 
practical battery power." 

1. Coil System. At 870 yards from centre to centre of 
coils, averaging each 200 yards diameter, with nine turns of 
wire, it was found that with a phonophore messages were sent 
with five dry cells, the resistance in primary being 30 ohms 
and the resistance of secondary 260 ohms, the current being 
0*23 ampere, which, with nine turns, gives 2 ampere turns. 

2. With a file as a make and break, it worked with 10 
cells, giving 0*4 ampere or 3 '6 ampere turns. 



3. Parallel-Wire System. With a file as a make and 
break, and with parallel lines earthed, it was heard with 
100 cells, giving 1*1 ampere. 

Mu&*lc Fluff yte. 




Fig. 15. 

The primary coil circuit was entirely metallic in the 
Murrayfield trials, as it would have to be if erected at 
Muckle Flugga ; but the secondary coil was earthed. 
When, however, the secondary was also made a complete 


insulated metallic circuit, with eight turns of wire, there 
seemed to be little difference in the result. 

The calculation of the diameter necessary to hear at a 
given distance is simple, from the fact that the hearing 
distance is proportional to the square root of the diameter 
of one of the coils, or directly as the diameter of the two 
coils, so that with any given number of amperes and 
number of turns, to hear double the distance requires 
double the diameter of coils, and so on. 1 

In concluding his paper, Mr Stevenson says : 

" It has been attempted to be shown that the coil system 
is not only theoretically but practically the best ; and I trust 
that we will soon hear of the Admiralty, &c., experimenting 
with it, and ultimately putting it in practice. Meantime my 
brother has recommended the Commissioners of Northern 
Lighthouses to erect the coil system at Muckle Flugga, and 
the Commissioners have approved ; and I hope soon to hear 
of the erection of this novel system of communication at the 
most northern point of the British Isles, as well as on our 
warships to assist in their manoeuvring, by the establish- 
ment of instantaneous communication unaffected by wind 
or weather. 

" The application of the coil system to communication with 
light vessels is obvious viz., to moor the vessel in the 
ordinary way, and lay out from the shore a cable, and circle 

1 Professor Lodge has recently shown that the law of distance is 
not the square root of diameter, but the two-thirds power, with a 
given primary current ; and so doubling the circumference of each 
coil will permit signalling over more than double the distance, if other 
things can be kept the same. For such magnification, however, the 
thickness of the wire must be magnified likewise, or else more power 
will be consumed in the enlarged coil ; and this consideration, as well 
as others, would speedily make the cost prohibitive, unless some fresh 
revolutionary devices are employed. For these see the ' Jour. Inst. 
Elec. Engs.,' No. 137, p. 803. 


the area over which the lightship moorings will permit her 
to travel by a coil of the cable of the required diameter, 
which will be twice the length of her chain cable. On 
board the vessel there will be another coil of a number of 
turns of thick wire. Ten cells on the lightship and ten on 
the shore will be sufficient for the installation." l 

In a recent communication 2 Mr Stevenson gives some 
additional particulars. Referring to his proposed installa- 
tion at the North Unst lighthouse, on Muckle Flugga, he 
tells us a gap of half a mile had to be bridged. The Com- 
missioners of Northern Lighthouses being impressed with 
the experiments shown them on a small scale even through 
stone and mortar decided on the larger experiment, but 
financial difficulties intervened, and the project was allowed 
to drop. 

" It is well to remember," he says, " that in the Murray- 
field trials a small number of cells was purposely used. 
Theory and formulae give one the impression at first sight 
that a single outstretched wire is always best the simple 
fact of getting a greater effect at a distance as a coiled wire 
is uncoiled and made straight supporting this impression ; 
but formulae, if they are to be practical, ought to take into 
account a limited area and workable amounts of resistance, 
current, &c., and then the fact is disclosed that the coiling 
of wires (whether condensers be used with them or not) be- 
comes an advantage for most work which the engineer will 
be called upon to deal with. 

1 Probably acting on Mr Stevenson's suggestion in the ' Engineer ' of 
Marcli 24, 1892, Mr Sydney Evershed devised a plan of communicat- 
ing with lightships, for which he applied for a patent on May 28, 1892. 
The method was actually tried in August 1896 on the North Sand 
Head (Goodwin) lightship, but failed utterly. See his patent speci- 
fication, No. 10,161 ; also his paper on Telegraphy by Magnetic 
Induction, 'Jour. Inst. Elec. Engs.,' No. 137, p. 852. 

2 ' Jour. Inst. Elec. Engs.,' No, 137, p, 951. 


"It is not necessary, as has been stated, that the coils 
should be identical in size and shape. Far from it; each 
case must be treated for size and configuration by itself. 
For instance, in the case of Muckle Flugga, my design was 
for a line two miles in length on the mainland, with a coil 
at the end enclosing a larger area than the one on the rock, 
which latter was opened out to the maximum possible. 
Again, in the case of Sule Skerry and the Flannan Islands, 
on the north-west of Scotland, where telegraphy by induc- 
tion would be of great value, it would be impossible to 
make the coils of large diameter, but the coil on the main- 
land should be of large dimensions ; indeed a single long 
wire with the ends earthed would be, perhaps, the best 

" For guarding a dangerous coast, a similar wire of many 
miles in length would be suitable for communicating warning 
signals to vessels on board of which were detectors, with 
coils necessarily of small dimensions. There are two ways 
of doing this, both of which I have tried. First, by means 
of a submarine cable along the line of coast. In this case 
the currents set up in the cable have to bridge only the 
sheet of water to the vessel, say twenty fathoms ; or, if an 
electro-magnet be let down from the ship, only four or five 
fathoms. But here the cost and maintenance of a cable 
would be a weighty objection. The other way is to erect a 
pole line on shore, either along the coast or in the form of 
a coil on a peninsula. The main difference from the first 
plan is that the currents would have to be stronger to bridge 
the distance of several miles instead of a few fathoms ; but 
the cost in comparison with a cable would be very small. 
I have tried this system with two miles of pole line and a 
coil about a quarter of a mile distant with perfect and 
never-failing success. 

" I have made numerous trials of the coil versus parallel- 


wire system since 1891, and I have found and other 
observers seem also to have found that it is not prac- 
tical to work the latter more than three or four times 
the length of base ; whereas by coils I have found it possible 
to work many times their diameter. Thus in 1892, at the 
Isle of May lighthouse, I signalled to a distance 360 times 
the diameter of an electro-magnet coil with currents from a 
de Meritens' magneto-electric machine. Again, at Murray- 
field, I signalled four times the base with five dry cells ; 
and I have in Edinburgh a coil with iron core 17 inches 
diameter, which with one cell can easily signal through a 
space twenty -five times its diameter." 1 


The last example of a wireless telegraph with which we 
have to deal in this part of our history is an arrangement 
devised by Prof. Rathenau of Berlin, with the assistance 
of Drs Rubens and W. Rathenau, and which was found 
to be practicable up to a distance of three miles in water. 

Reports of the experiments of Messrs Preece, Stevenson, 
and others in England having appeared in the technical 
journals on the Continent, Prof. Rathenau, at the request of 
the Berlin Electrical Society, undertook to make a thorough 
investigation of the subject de novo. 

After a careful study of the work of these electricians he 
felt convinced that the favourable results obtained in Eng- 
land, especially by Mr Preece, were largely due to conduc- 

1 Though never tried practically in England, Mr C. Bright points 
out that this system has been experimented on by the Lighthouse 
Board in America under the direction of Prof. Lucien Blake, and was 
favourably spoken of in their report for 1895 : ' Submarine Tele- 
graphs,' London, 1898. See also some recent remarks of Mr Steven- 
son, 'Jour. Inst. Elec. Engs.,' No. 139, p. 307. 



tion. To verify this opinion he commenced a course of 
rigorous experimentation ; and to prevent inductive effects 
entering into the calculation he decided to use ordinary 
battery currents, and in one direction only. 

The outcome of the inquiry was published in an article 
which he contributed to the Berlin ' Elektrotechnische 
Zeitschrift,' x from which I make a few extracts. When a 
current is sent through two electrodes immersed in a con- 
ducting liquid, the electrical equilibrium between these 

electrodes is not effected in a straight line, but in lines 
which spread out in the manner shown in fig. 16. Now, if 
we place in the liquid medium an independent conductor of 
electricity, it will attract or condense upon its surface a 
certain number of these lines, which can be utilised for the 
excitation of a properly constructed receiving apparatus. 
The distance at which these electrical effects can be produced 
is found to depend upon two factors the available current 
strength and the distance between the electrodes. 

It was thought best to conduct the experiments on the 

1 Abstract in ' Scientific American Supplement,' 'January 26, 1895, 
which I follow in the text. 


lake Wannsee, near Potsdam, on account of the facilities in 
the way of apparatus afforded by the proximity of an electric- 
light station. The arrangement is shown in fig. 16. AB is 
a battery of 25 cells, w a set of resistance coils (0 to 24 
ohms), su an interrupter driven by a motor, AM an ampere- 
meter, VM a voltmeter, T a Morse key, EP EP two zinc plates 
immersed in the water, 500 yards apart, and connected by 
cable as shown. The receiving circuit comprises two zinc 
plates, EP I and EP I , suspended by cable x from two boats, from 
50 to 100 yards apart, and nearly three miles from the 
sending station ; N N are telephones included in the circuit 
of x. For the purpose of transmitting signals, intermittent 
currents were sent from the battery, which, by depressing 
the key for long and short intervals, could be heard in the 
telephones as dashes and dots of the Morse code. 

The object was to establish experimentally the best 
relation between the various factors i.e., the relation 
between the current strength in the primary circuit and 
the hearing distance for the telephones in the secondary 
circuit ; the effect of various distances between the elec- 
trodes EP EP upon the clearness of the signals ; the dis- 
tance between EP X EP I which gave the most audible effect ; 
and, finally, the effect of altering the shape and size of 
the plates. 

On account of the non-arrival of some apparatus specially 
designed for these tests, the average current strength sent 
through the water did not exceed three amperes with 150 
intermissions or current impulses per second. Again, the 
water of the Wannsee containing but a very small ad- 
mixture of mineral salts offered a high resistance, so that 
it was found necessary to use large plates of 15 square 
yards surface. 

With this arrangement no difficulty was encountered 
in the transmission of signals from the electric-light station 


to the boats anchored off the village of New Cladow a 
distance, as has been said, of nearly three miles ; and 
Prof. Rathenau was satisfied that, by a slight change in 
the construction of the ordinary telephone, signals could 
be sent over much greater distances. 

"Lord Eayleigh," he says, "has stated that the sensi- 
tiveness of the telephone for currents with 600 reversals 
per second is about 600 times greater than for currents 
having but 130 reversals per second, but in my experi- 
ments the number of impulses did not exceed 150 per 
second. To get the best possible result in this system of 
transmission, a telephone should be used having a carefully 
tuned metallic tongue in place of the ordinary iron disc. 
Then, knowing the number of current-breaks in the primary 
circuit, the tongue should be so tuned as to vibrate in 
unison with that number, thereby producing much more 
distinct signals. 

" I may point out that the resistance of the receiving 
circuit should be as small as possible. At first I found 
it difficult to produce a call in the distant receivers, but 
this apparently knotty problem may be solved by attaching 
a microphone to the membrane of the receiver, which, 
acting upon a relay in a local circuit, produces the call. 

"It does not seem necessary to point out that by the 
use of several current generators, each one producing a 
definite number of current impulses, a number of non 
interfering messages may be sent through the water to 
distant telephones, each being constructed to respond to 
but one definite rate of vibration; or by means of one 
current generator a message may be sent (simultaneously) 
to several distant telephone receivers. 

"The usefulness of this method of transmission would 
be much increased if means can be found to produce a 
written message. On the suggestion of Dr Rubens an 



apparatus is now being constructed, generally on the plan 
of Dr Wien's optical telephone. It is expected that the 
use of this apparatus will enable us to transform the 
acoustical into optical signals, and to register these photo- 

Fig. 17 shows the locality of these experiments. It will 

Fig. 17. 

be noticed that a large sandbank intervenes between the 
stations, but without any appreciable effect on the results. 

Prof. Rathenau concludes a very interesting paper with 
the enumeration of the chief points to be observed for in- 
creasing the effective signalling distance : 

" 1. Great current strength in the primary circuit. 

"2. Increasing the distance between the primary 


"3. Increasing the distance between the receiving 

" 4. Replacing the metallic diaphragm of the telephone 
receiver by a light tongue. 

" 5. Which should be tuned to respond to a definite rate 
of vibration. 1 

1 Experiments, based on the same conductive principle, were 

tried in Austria about the same time, but with what success I 

cannot say, as the results, for military reasons, have not been 




" The invention all admired ; and each how he 
To be the inventor missed so easy seemed 
Once found, which yet unfound most would have thought 


MR PREECE, lately the distinguished engineer-in-chief of 
our postal telegraphs, has made the subject of wireless teleg- 
raphy a special study for many years, his first experiment 
dating back to 1882. 1 From that year up to the present he 
has experimented largely in all parts of the country, and 
has given us the results in numerous papers so numerous, 
in fact, that they offer a veritable enibarras des richesses to 
the historian. In what follows I can only attempt a resume, 
and that a condensed one ; but to the reader greatly 
interested in the subject I would advise a careful study of 
all the papers, a list of which I append : 

1. Recent Progress in Telephony : British Association 
Report, 1882. 

1 Indeed, it so happens that one of the first experiments he ever 
made in electricity was on this very subject in 1854. See p. 28, 


2. On Electric Induction between Wires and Wires : British 

Association Report, 1886. 

3. On Induction between Wires and Wires : British Associa- 

tion Report, 1887. 

4. On the Transmission of Electric Signals through Space : 

Chicago Electrical Congress, 1893. 

5. Electric Signalling without Wires : Journal of the Society 

of Arts, February 23, 1894. 

6. Signalling through Space : British Association Report, 


7. Telegraphy without Wires : Toynbee Hall, December 12, 


8. Signalling through Space without Wires : Royal Institu- 

tion, June 4, 1897. 

9. ^theric Telegraphy : Institution of Electrical Engineers, 

December 22, 1898. 1 

In his first-quoted paper of 1882, speaking of disturb- 
ances on telephone lines, Mr Preece says : " The discovery 
of the telephone has made us acquainted with many strange 
phenomena. It has enabled us, amongst other things, to 
establish beyond a doubt the fact that electric currents 
actually traverse the earth's crust. The theory that the 
earth acts as a great reservoir for electricity may be placed 
in the physicist's waste-paper basket, with phlogiston, the 
materiality of light, and other old-time hypotheses. Tele- 
phones have been fixed upon a wire passing from the ground 
floor to the top of a large building (the gas-pipes being used 
in place of a return wire), and Morse signals, sent from a 
telegraph office 250 yards distant, have been distinctly read. 
There are several cases on record of telephone circuits miles 
away from any telegraph wires, but in a line with the earth 
terminals, picking up telegraphic signals ; and when an 
electric-light system uses the earth, it is stoppage to all 
telephonic communication in its neighbourhood. Thus, 

1 This list does not pretend to be complete. Doubtless there are 
other papers, which have escaped my notice. 


communication on the Manchester telephones was not long 
ago broken down from this cause ; while in London the 
effect was at one time so strong as not only to destroy all 
correspondence, but to ring the telephone - call bells. A 
telephone system, using the earth in place of return wires, 
acts, in fact, as a shunt to the earth, picking up the currents 
that are passing in proportion to the relative resistances of 
the earth and the wire." J 

Mr Preece then describes the experiment which he had 
recently (March 1882) made of telegraphing across the 
Solent, from Southampton to Newport in the Isle of Wight, 
without connecting wires. " The Isle of Wight," he says, 
"is a busy and important place, and the cable across at 
Hurst Castle is of consequence. For some cause the cable 
broke down, and it became of great importance to know if 
by any means we could communicate across, so I thought it 
a timely opportunity to test the ideas that had been promul- 
gated by Prof. Trowbridge. I put a plate of copper, about 
6 feet square, in the sea at the end of the pier at Hyde (fig. 
18). A wire (overhead) passed from there to Newport, and 
thence to the sea at Sconce Point, where I placed another 
copper plate. Opposite, at Hurst Castle, was a similar 
plate, connected with a wire which ran through Southamp- 
ton to Portsmouth, and terminated in another plate in the 
sea at Southsea Pier. We have here a complete circuit, if 
we include the water, starting from Southampton to South- 
sea Pier, 28 miles ; across the sea, 6 miles ; Eyde through 
Newport to Sconce Point, 20 miles ; across the water again, 
1J mile; and Hurst Castle back to Southampton, 24 miles. 

" We first connected Gower-Bell loud-speaking telephones 

in the circuit, but we found conversation was impossible. 

Then we tried, at Southampton and Newport, what are 

called buzzers (Theiler's Sounders) little instruments that 

1 For early notices of the same kind, see pp. 79-85, ante. 



make and break the current very rapidly with a buzzing 
sound, and for every vibration send a current into the 
circuit. With a buzzer, a Morse key, and 30 Leclanche 
cells at Southampton, it was quite possible to hear the 
Morse signals in a telephone at Newport, and vice versa. 

Fig. 18. 

Next day the cable was repaired, so that further experi- 
ment was unnecessary." 1 

Mr Preece, however, kept the subject in view, and in 
1884 he began a systematic investigation, theoretically and 
experimentally, of the laws and principles involved an 

1 Captain Hippisley, R.E., who conducted these trials, thought 
that the presence of the broken cable across the Solent somewhat 
vitiated the results, as its heavy iron sheathing may have aided in 
conducting the current. 


investigation which he has hardly yet completed. In his 
papers read at the International Electrical Congress, 
Chicago, August 23, 1893, and at the Society of Arts, 
London, February 23, 1894, he gives a resume of his 
experiments from 1884 to date. 

He begins the latter paper by asking the same momen- 
tous question which a lady once put to Faraday, What 
is electricity? Faraday, with true philosophic caution, 
replied (I quote from memory) : " Had you asked me forty 
years ago, I think I would have answered the question ; 
but now, the more I know about electricity, the less pre- 
pared am I to tell you what it is." Mr Preece is not 
quite so epigrammatic, nor nearly so cautious; but, then, 
we have learned a great deal since Faraday's time. " Few," 
he says, "venture to reply boldly to this question first, 
because they do not know ; secondly, because they do 
not agree with their neighbours, even if they think they 
know ; thirdly, because their neighbours do not agree 
among themselves, even as to what to apply the term. 
The physicist applies it to one thing, the engineer to 
another. The former regards his electricity as a form 
of ether, the latter as a form of energy. I cannot grasp 
the concept of the physicist, but electricity as a form of 
energy is to me a concrete fact. The electricity of the 
engineer is something that is generated and supplied, 
transformed and utilised, economised and wasted, meted 
out and paid for. It produces motion of matter, heat, 
light, chemical decomposition, and sound; while these 
effects are reversible, and sound, chemical decomposition, 
light, heat, and motion reproduce those effects which are 
called electricity." 1 

1 " Substantialists " call it a kind of matter. Others view it as a 
form of energy. Others, again, reject both these views. Prof. 
Lodge considers it a form, or rather a mode of manifestation, of the 


In experiments of this kind it is necessary to point out 
that if we have two parallel conductors, separated from 
each other by a finite space, and each forming part of 
a separate and distinct circuit, either wholly metallic or 
partly completed by the earth, and called respectively the 
primary and the secondary circuits, we may obtain currents 
in the latter either by conduction or by induction ; and we 
may classify them into those due to 

1. Earth-currents or leakages. 

2. Electro-static induction currents. 

3. Electro-magnetic induction currents. 

It is very important to eliminate (1), which is a case of 
conduction, from (2) and (3), which are cases of induction, 
pure and simple. 

1. Earth-cuirents or Leakages. 

When a linear conductor dips at each end into the earth, 
and voltage is impressed upon it by any means, the result- 
ing return current would probably flow through the earth 
in a straight line between these two points if the conducti- 
bility of the earth were perfect ; but as the earth, per se, 
is a very poor conductor (and probably is so only because 
it is moist), lines of current-flow spread out symmetrically 
in a way that recalls the figure of a magnetic field. These 
diffused currents are evident at great distances, and can 
be easily traced by means of exploring earth -plates or 
rods. The primary current is best produced by alternating 
currents of such a frequency as to excite a distinct musical 

ether. Prof. Nikola Tesla demurs to this view, but sees no objection 
to calling electricity ether associated with matter, or bound ether. 
High authorities cannot even yet agree whether we have one elec- 
tricity or two opposite electricities. 


note in a telephone, and if these currents rise and fall 
periodically and automatically, they produce an unmistak- 
able wail, which, if made and broken by a Morse key into 
short and long periods, can be made to represent the dots 
and dashes of the Morse alphabet. The secondary circuit, 
which contains the receiving telephone, is completed in the 
case of an earth area by driving two rods into the ground, 
and in the case of water by dipping plates therein, 5 to 10 
yards apart. 

It is therefore necessary to be able to distinguish these 
earth-currents from those due to induction, as they are apt 
to give false effects, and to lead to erroneous conclusions. 
This is easily done, if the instrument be sensitive enough, 
by making the primary current continuous when the earth- 
current also becomes continuous, whereas the induction 
currents will be momentary, and will only be observed 
at the beginning and end of the primary or inducing 

2. Electro-static Induction Currents. 

When a body, A, is electrified by any means and isolated 
in a dielectric, as air, it establishes an electric field about 
it ; and if in this field a similar body, B, be placed, it also 
is electrified by induction. If B be placed in connection 
with the earth, or with a condenser, or with any very large 
body, a charge of the same sign as A is conveyed away, and 
it (B) remains electrified in the opposite sense to A. A and 
B are now seats of electric force or stress. The dielectric 
between them is displaced or, as we say, polarised that 
is, it is in a state of electric strain, and remains so as long 
as A remains charged ; but if A be discharged, or have its 
charge reversed or varied, then similar changes occur in B, 
and in the dielectric separating them. A may be an ex- 
tended wire forming part of a, complete primary circuit, 


and its charge may be due to a battery or other source of 
electricity; then, in the equally extended secondary wire 
B (fig, 19), the displaced charge in flowing to earth estab- 
lishes a momentary current whose direction and duration 
depend on the current in A, and on its rate of variation. 

Fig. 19. 

The strained (polarised) state of the dielectric, and the 
charges on A and B, remain quiescent so long as the current 
flows steadily ; but when it ceases we have again, and in 
loth circuits, momentary currents, as shown by the arrows 
(fig. 20), which flow until equilibrium is restored. 

Fig. 20. 

The secondary currents due to discharge, like those due 
to charge, flow in opposite directions at each end, and there 
is always some intermediate zero point. 

It is thus easy in long circuits, by observing their direc- 
tion, to differentiate currents of induction due to electro- 
static displacement from those due to electro - magnetic 

The effects of electro-static induction do not play an 
important part in the inquiry immediately before us, but 
they are of great consequence in questions of speed of sig- 


nailing in submarine cables and long, well-insulated land- 
lines, and in clearness of speech in long-distance telephony. 1 

3. Electro-magnetic Induction Currents. 

Magnetic force is that which produces, or tends to pro- 
duce, polarisation in inagnetisable matter (as iron, nickel, 
cobalt), and electro-magnetic disturbance or stress in non- 
magnetisable matter and the ether. An electric current in 
a conductor is a seat of magnetic force, and establishes in 
its neighbourhood a magnetic field. The lines of force in 
this field are equivalent to circles in a plane perpendicular 
to the direction of the current, which circles, during the rise 
of the current, flow outwards or expand, and, during the 
fall of the current, flow inwards or contract, much like the 
waves on the surface of smooth water when a pebble is 
thrown in, but moving with the speed of light. Thus any 
linear conductor placed in the field of another parallel con- 
ductor carrying a current is cut at right angles to itself by 
these lines of force in one direction as the current rises, 
and in the opposite direction as the current falls. This out- 
ward and inward projection of magnetic force through such 
linear conductor excites electric force in that conductor, and 
if it form part of a circuit an electric current is set up in 
that circuit. 

So far for the theory of the subject. Now for its experi- 
mental elucidation. Besides those cases of interference 
mentioned on page 137, others were of frequent occurrence 
in the experience of the postal-telegraph officials, the most 
striking being that known as the Gray's Inn Road case. In 
1884 it was there noticed that messages sent in the ordinary 

1 For an interesting investigation of electro -static phenomena on 
telephone circuits, see Mr Carty's papers in the ' Electrician,' Decem* 
ber 6, 1889, and April 10, 1891. 


way through insulated wires, buried in iron pipes along the 
road, could be read upon telephone circuits erected on poles 
on the house-tops 80 feet high. To cure the evil the tele- 
graph wires had to be taken up and removed to a more 
distant route. 1 

In 1885 Mr Preece arranged an exhaustive series of ex- 
periments in the neighbourhood of Newcastle, which were 
ably carried out by Mr A. "W. Heaviside, to determine 
whether these disturbances were due to electro-magnetic in- 
duction, and were independent of earth conduction ; and 
also to find out how far the distance between the wires 
could be extended before this influence ceased to be evi- 
dent. Insulated squares of wire, each side being 440 yards 
long, were laid out horizontally on the ground one quarter 
of a mile apart, and distinct speech by telephones was 
carried on between them ; while when removed 1000 yards 
apart inductive effects were still appreciable. 

With the parallel lines of telegraph, ten and a quarter 
miles apart, between Durham and Darlington, the ordinary 
working currents in the one were clearly perceptible in a 
telephone on the other. Even indications were obtained in 
this way between Newcastle and Gretna, on the east and 
west coasts, forty miles apart ; but here the observations 
were doubtless vitiated by conduction or leakage through 

1 The following are more recent cases of the same kind. Currents 
working the City and South London Electric Railway affect recording 
galvanometers at the Greenwich Observatory, four and a half miles 
distant ; and even a diagram of the train service could be made out 
by tapping any part of the metropolitan area. 

Some ten years ago one of the dynamos at the Ferranti electric- 
light station at Deptford by some accident got connected to earth, 
with the result that the whole of the railway telegraphs in the signal- 
boxes of the railways in South London were temporarily put out of 
order and rendered inoperative, while the currents flowing in the 
earth were perceived in the telegraph instruments so far northwards 
as Leicester and so far south as Paris. 


the large network of telegraph wires between those two 
places. 1 

The district between Gloucester and Bristol, along the 
banks of the Severn, was next (1886) selected, where for a 
length of fourteen miles, and an average distance apart of 
four and a half miles, no intermediate disturbing lines 
existed. Complete metallic circuits were employed, the 
return wires passing far inland, in the one case through 
Monmouth, and in the other through Stroud. In one wire 
currents of about *5 ampere were rapidly made and broken 
by mechanical means, producing on a telephone a continuous 
note which could be broken up by a Morse key into dots 
and dashes, as in Cardew's vibrator. Weak disturbances 
were detected in the secondary circuit, showing that -here 
the range of audibility with the apparatus in use was just 
overstepped. The unexpected fact was also shown in these 
experiments that, whether the circuits were entirely metallic 
or earthed at the ends, the results were the same. 2 

Similar trials were made on lines along the valley of the 
Mersey. A new trunk line of copper wires that was being 
erected between London and the coast of North Wales was 
then experimented upon, and some interesting results were 
obtained in the district between Shrewsbury and Much 
Wenlock, and between Worcester and Bewdley. 

In the autumn of the same year (1886) some admirable 
results were obtained by Mr Gavey, another of Mr Preece's 
able assistants, near Porthcawl, in South Wales a wide 
expanse of sand well covered by the tide, thus giving the 
opportunity of observing the effects in water as well as in 
air. Two horizontal squares of insulated wire, 300 yards 
each side, were laid side by side at various distances apart 

1 British Association Report, 1886. 

3 These experiments were repeated with more experience and 
greater success in 1889. 


up to 300 yards, and the inductive effects of one on the 
other noted. Then one coil was suspended on poles. 15 feet 
above the other, which was covered with water at high tide. 
JS"o difference was observable in the strength of the induced 
signals, whether the intervening space was air or water or a 
combination of both, although subsequent experience (1893) 
showed that with a space of 15 feet the effect in air was 
distinctly better than through water. 

The conclusion drawn from all these, experiments was 
that the magnetic field extends uninterruptedly through the 
earth, as it does through the air ; and that if the secondary- 
circuit had been in a coal-pit the effect would be the same. 
In fact, Mr Arthur Heaviside succeeded in 1887 in com- 
municating between the surface and the galleries of Broom- 
hill Colliery, 350 feet deep. He arranged a circuit in a 
triangular form along the galleries about two and a quarter 
miles in total length, and at the surface a similar circuit of 
equal size over and parallel to the underground line. Tele- 
phonic speech was easily carried on by induction from circuit 
to circuit. 1 

As the result of all these experiments and innumerable 
laboratory investigations, Mr Preece deduced the following 
formula. The first shows the strength of current C 2 in- 
duced in the secondary circuit by a given current C x in the 
primary circuit 

1 Subsequent experiments showed that the conclusion arrived at 
for earth and air was only partially true for water. Telephonic 
speech was carried on in Dover Harbour through 36 feet of water, 
but no practical signals could be obtained through 400 feet at North 
Sand Head, Goodwin Sands, showing that the effect must diminish 
in water with some high power of the distance. 

2 This formula does not allow for the reverse effect of the return 
current through the earth, as to which no data exist at present. 


where R equals the resistance of the secondary circuit, D the 
distance apart of the two circuits, L the length of the in- 
ductive system, and I the inductance of the system. The 
value of I, obtained by experiment on two parallel squares 
of wire, 1200 yards round and 5 yards apart, was found to 
be -003. 

The second equation gives approximately the maximum 
distance X which should separate any two wires of length 
L, C x being the primary current and R the resistance of the 
secondary circuit. 

X = 1.9016- 

The constant 1*9016 was obtained by experimenting on two 
parallel wires, each one mile long, when the primary circuit, 
being excited by one ampere, the limit of audibility in the 
secondary was reached at 1 '9016 miles. This formula shows 
the desirability of using copper wires of the largest size 
practicable, so as to reduce the value of R. Other very 
important elements of success are (1) the rate at which the 
primary currents rise and fall, the faster the better, and (2) 
the reduction to a minimum of such retarding causes as 
capacity and self-induction. 

Having thus threshed out the laws and conditions of 
electro-magnetic disturbances, and determined the distance 
at which they could be usefully applied, it only remained 
for Mr Preece to put his conclusions to a practical test. 
Accordingly, when the Royal Commission on electric com- 
munication between the shore and lighthouses and light- 
ships was appointed in June 1892, he made his proposals to 
the Government, arid on receiving sanction forthwith pro- 
ceeded to carry them out. 

The Bristol Channel proved a very convenient locality to 
test the practicability of communicating across distances of 



three and five miles without any intermediate conductors. 
Two islands, the Flat Holm and the Steep Holm, lie off 
Penarth and Lavernock Point, near Cardiff, the former 
having a lighthouse upon it (fig. 21). On the shore two 
thick copper wires combined in one circuit were suspended 
on poles for a distance of 1267 yards, the circuit being 





Fig. 21. 

completed by the earth. On the sands at low-water mark, 
600 yards from this primary circuit and parallel to it, two 
gutta-percha covered copper wires and one bare copper wire 
were laid down, their ends being buried in the ground by 
means of bars driven in the sand. 

One of the gutta-percha wires was lashed to an iron wire 
to represent a cable. These wires were periodically covered 


by the tide, which rises here at spring to 33 feet. On the 
Flat Holm, 3 '3 miles away, another gutta-percha covered 
copper wire was laid for a length of 600 yards. 

There was also a small steam launch having on board 
several lengths of gutta-percha covered wire. One end 
of such a wire, half a mile long, was attached to a small 
buoy, which acted as a kind of float to the end, keeping 
the wire suspended near the surface of the water as it 
was paid out while the launch slowly steamed ahead 
against the tide. Such a wire was paid out and picked 
up in several positions between the primary circuit and the 

The apparatus used on shore was a 2-h.p. portable 
Marshall's engine, working a Pyke and Harris's alternator, 
sending 192 complete alternations per second of any desir- 
able strength up to a maximum of 15 amperes. These 
alternating currents were broken up into Morse signals by a 
suitable key. The signals received on the secondary circuits 
were read on a pair of telephones the same instruments 
being used for all the experiments. 

The object of the experiments was not only to test the 
practicability of signalling between the shore and the light- 
house, but to differentiate the effects due to earth conduction 
from those due to electro-magnetic induction, and to deter- 
mine the effects in water. It was possible to trace without 
any difficulty the region where they ceased to be perceptible 
as earth-currents and where they commenced to be solely 
due to electro-magnetic waves. This was found by allowing 
the paid-out cable, suspended near the surface of the water, 
to sink. Near the shore no difference was perceptible, 
whether the cable was near the surface or lying on the 
bottom, but a point was reached, just over a mile away, 
where all sounds ceased as the cable sank, but were received 
again when the cable came to the surface. The total 


absence of sound in the submerged cable was rather sur- 
prising, and led to the conclusion either that the electro- 
magnetic waves of energy are dissipated in the sea-water, 
which is a conductor, or else that they are reflected away 
from the surface of the water, like rays of light. 

Experiments on the Con way Estuary, showing the relative 
transparency of air and water to these electro-magnetic 
waves, tend to support the latter deduction ; for if much 
waste of energy took place in the water, the difference 
would be more marked. As it is, there seems to be ample 
evidence that the electro-magnetic waves are transmitted to 
considerable distances through water, though how far remains 
to be found. 1 

There was no difficulty in communicating between the 
shore and Flat Holm, 3 '3 miles. The attempt to speak 
between Lavernock and Steep Holm, 5 -35 miles, was not 
so successful : though signals were perceptible, conversation 
was impossible. There was distinct evidence of sound, but 
it was impossible to differentiate the sounds into Morse 
signals. If either line had been longer, or the primary 
currents stronger, signalling would probably have been 

In 1894 Mr Preece carried out some satisfactory experi- 
ments near Frodsham, on the estuary of the Dee, which 
was found to be a more convenient locality than the 
Conway sands. Here, as at Conway and other places, 
squares and rectangles were formed of insulated wires, 
and numerous measurements were made (with reflecting 
galvanometers and telephones) of the effects due to vary- 
ing currents in the primaries, and at varying distances 
between them and the secondaries. 

In Scotland also some very successful trials were made. 
There happens to be a very convenient and accessible loch 
1 See note, p. 147, ante. 


in the Highlands Loch Ness forming part of the route 
of the Caledonian Canal between Inverness and Banavie, 
having a line of telegraph on each side of it. Five miles 
on each side of this loch were taken, and so arranged that 
any fractional length of telegraph wire on either side could 
be taken for trial. Ordinary, and not special, apparatus 
was employed. Sending messages, as before, by Morse 
signals and speaking by telephone across a space of one 
and a quarter miles was found practical, and, in fact, easy ; 
indeed, the sounds were so loud that they were found 
sufficient to form a call for attention. 

The following apparatus was in use on each side of 
the loch : A set of batteries consisting of 100 dry cells, 
giving a maximum voltage of 140 ; a rapidly revolving 
rheotome, which broke up the current into a musical 
note; a Morse key, by which these musical notes could 
be transformed into Morse signals ; resistance coils and 
ampere - meters to vary the primary current ; two Bell 
telephones joined in multiple arc to act as receivers. 
For the transmission of actual speech simple granular 
carbon microphones, known as Deckert's, were used as 
transmitters, and a current of two amperes was main- 
tained through these and two Bell telephones in circuit 
with the line wire. 

Any lingering fear that earth conduction had principally 
to do with these results was removed by making the earth's 
terminals on the primary circuit at one end at Inverness 
nine miles away, and at the other end in two directions 
in a parallel glen about six miles away. 

One very interesting fact observed at Loch Ness was 
that there was one particular frequency in the primary 
circuit that gave a decided maximum effect upon the 
telephones in the secondary circuit. This confirms the pres- 
ence of resonance, and is, of itself, a fact sufficient to prove 



the effects as being due to the transformation of electro- 
magnetic waves into electric currents. 1 

During the same year (1894) experiments were carried 
out between the island of Arran and Kintyre across Kil- 



Fig. 22. 

brannan Sound. Two parallel lines on opposite sides, and 
four miles apart, were taken (fig. 22) ; and, in addition, 
two gutta-percha covered wires were laid along each coast, 
at a height of 500 feet above sea-level and five miles apart 

1 This is still a moot question, many competent authorities, as 
Lodge, Rathenau, W. S. Smith, and Stevenson, being of opinion that 
the effect is partly inductive and partly conductive. See Dr Lodge's 
contention, 'Jour. Inst. Elec. Engs.,' No. 137, p. 814, 


' Incidentally some extremely interesting effects of electro- 
magnetic resonance were observed during the experiments 
in Arran. A metallic circuit was formed partly of the 
insulated wire 500 feet above the sea -level and partly 
of an ordinary line wire, the rectangle being two miles 
long and 500 feet high. Wires on neighbouring poles, 
at right angles to the shorter side of the rectangle, cdthoucjli 
disconnected at both ends, took up the vibrations, and it 
was possible to read all that was signalled on a telephone 
placed midway in the disconnected circuit by the surgings 
thus set up. 

The general conclusions arrived at as the result of these 
numerous and long-continued experiments may be briefly 
summed up as follows : l 

The earth acts simply as a conductor, and per se it is a 
very poor conductor, deriving its conducting property prin- 
cipally, and often solely, from the moisture it contains. On 
.the other hand, the resistance of the " earth " between the 
two earth plates of a good circuit is practically nothing. 
Hence it follows that the mass of earth which forms the 
return portion of a circuit must be very great, for we know 
by Ohm's law that the resistance of a circuit increases with 
its specific resistance and length, and diminishes with its 
sectional area. Now, if the material forming the " earth " 
portion of the circuit were, like the sea, homogeneous, the 
current-flow between the earth plates would follow innumer- 
able but definite stream lines, which, if traced and plotted 
out, would form a hemispheroid. These lines of current 
have been traced and measured. A horizontal plan on the 
surface of the earth is of the form illustrated in fig. 23, 
while a vertical section through the earth is of the form 
shown in fig. 24. 

With earth plates 1200 yards apart these currents have 
. l British Association Report, 1894, Section G. 


been found on the surface at a distance of half a mile 
behind each plate; and, in a line joining the two trans- 

'-"' ---*'" - . X \ 

. \ ' .';''''''*-'','-- "-"_""- O\\ \ I 

v\ \ t i ;'/.-'/,.'-;. -*Xcr**C\V: / *v 

% * V- V^^^'::'v'.'.'.'.'"'' - - - -;;;f; : 3 rrji^^lr f f - 

Fig. 23. 

versely, they are evident at a. similar distance at right 
angles to this line. 

Now this hemispheroidal mass could be replaced electric- 
ally by a resultant conductor (R, fig. 24) of a definite form 

Fig. 24. 

and position ; and, in considering the inductive action be- 
tween two circuits having earth returns, it is necessary to 
estimate the position of this imaginary conductor. This 
was the object of the experiments at Frodsham. 

If the material of the earth be variable and dry the he mi- 


spheroid must become very much deformed and the section 
very irregular: the lines of current-flow must spread out 
farther, but the principle is the same, and there must be a 
resultant return. The general result of the experiments at 
Frodsham indicates that the depth of the resultant earth 
was 300 feet, while those at Conway are comparable with a 
depth of 350 feet. In the case of Frodsham the primary 
coil had a length of 300 feet, while at Conway the length 
was 1320 feet. At Loch Ness, and between Arran and 
Kintyre, where the parallel lines varied from two to four 
miles, the calculated depth was found to be about 900 feet. 
The depth of this resultant must, therefore, increase with the 
distance separating the earth plates, and this renders it pos- 
sible to communicate by induction from parallel wires over 
much longer distances than would otherwise be possible. 

The first and obvious mode of communicating across space 
is by means of coils of wire opposed to each other in the 
way familiar to us through the researches of Henry and 
Faraday. All the methods here described consisted in 
opposing two similar coils of wire having many turns, the 
one coil forming the primary circuit and the other coil the 
secondary circuit. 

Vibratory or alternating currents of considerable fre- 
quency were sent through the primary circuit, and the 
induced secondary currents were detected by the sound 
or note they made on a telephone fixed in the secondary 

The distance to which the effective field formed by a coil 
extends increases with the diameter of the coil more than 
with the number of turns of wire upon it. A single wire 
stretched across the surface of the earth, forming part of a 
circuit completed by the earth, is a single coil, of which the 
lower part is formed by the resultant earth return, and the 
distance to which its influence extends depends upon the 


height of the wire above the ground and the depth of this 
resultant earth. 

In establishing communication by means of induction, 
there are three dispositions of circuit available viz., (a) 
single parallel wires to earth at each extremity ; (b) parallel 
coils of one or more turns ; (c) coils of one or more turns 
placed horizontally and in the same plane. 

The best practical results are obtained with the first 
arrangement, more especially if the conformation of the 
earth admits of the wires being carried to a considerable 
height above the sea, whilst the earth plates are at the sea- 
level. By adopting this course the size of the coil is prac- 
tically enlarged, and even if it be necessary to increase the 
distance between the parallel wires in order to get a larger 
coil, the result is still more beneficial In a single-wire 
circuit we have the full effect of electro-static and electro- 
magnetic induction, as well as the benefit of any earth con- 
duction, but in closed coils we have only the electro-magnetic 
effects to utilise. 

In one experiment two wires of a definite length were 
first made up into two coils forming metallic circuits, then 
uncoiled and joined up as straight lines opposed to each 
other, with the circuit completed by earth. The effects, 
and the distance between which they were observable, were 
very many times greater with the latter than with the former 

The general law regulating the distance to which we can 
speak by induction has not been rigorously determined, and 
it is hardly possible that it can be done, owing to the many 
disturbing elements, geological as well as electrical. In 
practice we have to deal with two complete circuits of un- 
known shape, and in different planes. We have obtained 
some remarkably concordant and accurate results in one 
place ; but, on the other hand, we have met with equally 


discordant results in another place. Still, from the ap- 
proximate formula before given, we deduce the important 
fact that for parallel lines the limiting distance increases 
directly as the square of the length, which shows that if we 
can make the length of the two lines long enough it would 
be easy to communicate across a river or a channel. Of 
course, as previously pointed out, the formula does not take 
into account the effects of the reverse magnetic waves gener- 
ated by the return current through the earth, and at present 
no data exist on which a satisfactory calculation can be 
based ; but, for example, there is little doubt that two wires, 
ten miles long, would signal through a distance of ten miles 
with ease. 

" Although," says Mr Preece in conclusion, " communi- 
cation across space has thus been proved to be practical 
in certain conditions, those conditions do not exist in the 
cases of isolated lighthouses and light-ships, cases which 
it was specially desired to provide for. The length of 
the secondary must be considerable, and, for good effects, 
at least equal to the distance separating the two conductors. 
Moreover, the apparatus to be used on each circuit is 
cumbrous and costly, and it may be more economical to 
lay an ordinary submarine cable. 

" Still, communication is possible even between England 
and France, across the Channel, and it may happen that 
between islands where the channels are rough and rugged, 
the bottom rocky, and the tides fierce, the system may be 
financially possible. It is, however, in time of war that it 
may become useful. It is possible to communicate with a 
beleaguered city either from the sea or on the land, or 
between armies separated by rivers, or even by enemies. 

"As these waves are transmitted by the ether, they are 
independent of day or night, of fog, or snow, or rain, and 
therefore, if by any means a lighthouse can flash its indicat- 


ing signals by electro-magnetic disturbances through space, 
ships could find out their positions in spite of darkness and 
of weather. Fog would lose one of its terrors, and elec- 
tricity become a great life-saving agency." 

At the Society of Arts (February 23, 1894), Mr Preece 
gave rein to his imagination, and, looking beyond these 
mundane utilities, concluded his address with the following 
magnificent peroration : 

" Although this short paper is confined to a description of 
a simple practical system of communicating across terrestrial 
space, one cannot help speculating as to what may occur 
through planetary space. Strange mysterious sounds are 
heard on all long telephone lines when the earth is used as 
a return, especially in the calm stillness of night. Earth- 
currents are found in telegraph circuits and the aurora 
borealis lights up our northern sky when the sun's photo- 
sphere is disturbed by spots. The sun's surface must at 
such times be violently disturbed by electrical storms, and 
if oscillations are set up and radiated through space, in 
sympathy with those required to affect telephones, it is not 
a wild dream to say that we may hear on this earth 'a 
thunderstorm in the sun. 

" If any of the planets be populated with beings like our- 
selves, having the gift of language and the knowledge to 
adapt the great forces of nature to their wants, then, if they 
could oscillate immense stores of electrical energy to and fro 
in telegraphic order, it would be possible for us to hold 
commune by telephone with the people of Mars." 

The first application of Mr Preece's system to the ordinary 
needs of the postal-telegraph service was made on March 30, 
1895, when the cable between the Isle of Mull and Oban, 
in Scotland, broke down. As there was no ship available 
at the moment for effecting repairs, communication was 
established by laying a gutta-percha-covered copper wire, 



one and a half mile long, along the ground from Morven, 
on the Argyllshire coast, while on Mull the ordinary tele- 
graph (iron) wire connecting Craignure with Aros was used, 
the mean distance separating the two base lines being about 
two miles. No difficulty was experienced in keeping up 
communication, and many public messages were transmitted 
for a week until the cable was repaired. In all about 160 
messages were thus exchanged, including a press telegram 
of 120 words. 



Fig. 25. 

The diagram (fig. 25) shows the apparatus and connec- 
tions, as regards which it is only necessary to say that a is 
a rheotome, or make-and-break wheel, driven so as to pro- 
duce about 260 interruptions of the current per second, 
which give a pleasant note in the telephone, and are easily 
read when broken up by the key into Morse dots and 
dashes; & is a battery of 100 Leclanche cells, of the so- 
called dry and portable type ; c is a switch to start and stop 


the rheotome as required ; and d is a telephone to act as 

Since March of last year (1898) this system has been 
permanently established for signalling between Lavernock 
Point and the Flat Holm, and has been handed over to the 
"War Office. Permanent lines of heavy copper wire have 
been erected parallel to each other, one being on the Flat 
Holm and the other on the mainland. 

The heavy and cumbrous Pyke and Harris alternator of 
the earlier experiment over the same line (p. 150, ante) has 
been replaced by 50 Leclanche cells. The frequency has 
been raised to 400 makes and breaks per second, thus greatly 
increasing the strength of the induced currents. By the 
use of heavy copper base lines the resistances have been 
made as low as practicable. There is no measurable capac- 
ity, self-induction is eliminated, and there is no impedance. 
Hence the signals are perfect, and the rate of working is 
only dependent on the skill of the operator. It is said that 
as many as 40 words per minute have been transmitted 
without the necessity for a single repetition a speed which 
few telegraphists can achieve, and still fewer can keep up. 

Last summer Mr Sydney Evershed's relays were added 
to work a call-bell, which was the only thing wanted to 
make the system complete and practical. 1 

It should be added, in conclusion, that the installation 
was carried out under the immediate superintendence of Mr 
Preece's able assistant, Mr Gavey, who for many years has 
been intimately associated with him in these researches. 

1 For a description of this very sensitive instrument see Evershed's 
paper, 'Jour. Inst. Elec. Engs.,' No. 137, p. 864. 



Mr Smith's researches in wireless telegraphy date back to 
1883. His first suggestions, of the induction order, were 
contained in a paper on Voltaic-Electric Induction, which 
he read before the Institution of Electrical Engineers on 
November 8 of that year. These have already been noticed 
in our account of Edison's invention (p. 105, ante). 

Somewhat later, early in 1885, Mr Smith turned his 
attention to conduction methods, and worked out a plan 
which, in a modified form, has been in actual operation for 
the last three years. 

The rationale of the system is described by Mr Smith as 
follows : 

" Messages have been sent and correctly received through 
a submarine cable two thousand miles in length, the earth 
being the return half of the circuit, by the aid of the elec- 
tricity generated by means of an ordinary gun-cap containing 
one drop of water ; and small though the current emanating 
from such a source naturally was, yet I believe it not only 
polarised the molecules of the copper conductor, but also in 
the same manner affected the whole earth through which it 
dispersed on its way from the outside of the gun-cap to its 
return, through the cable, to the water it contained. I further 
believe that the time will come, perhaps sooner than may be 
expected, when it will be possible to detect even such small 
currents in any part of the world in the same way that it is 
now possible to do in comparatively small sections of it. 

" For researches of this description it is necessary to employ 
as sensitive an instrument as it is possible to obtain, to pick 
up, so to speak, such minute currents. Now, there is that 
wonderful instrument the telephone. I say wonderful ad- 
visedly, for as far as I know it is not to be equalled for the 


simplicity of its mechanical construction and the ease with 
which it can be manipulated, and yet is so peculiarly sensi- 
tive. I have used it in most of my experiments as the 
receiving instrument, although of course there are other 
well-known instruments that could be employed, as all 
depends upon the potential of the current to be detected. 
The sending arrangement was either an ordinary Morse key 
so manipulated for a short or long time as to give the neces- 
sary sounds in the telephone to represent dots and dashes, 
or a double key and two pieces of mechanism giving dis- 
similar sounds were employed with good results. I gave 
much time and thought to the subject, the results of each 
experiment giving me much encouragement to proceed. 

" Of the many experiments made I select the following, 
as I think it will clearly illustrate my system for telegraph- 
ing to a distant point not in metallic connection with the 
sending station. A wooden bathing-hut on a sandy beach 
made a good shore station, from which were laid two in- 
sulated copper wires 115 fathoms in length. The ends of 
the wires, scraped clean, were twisted round anchors, their 
position being marked by buoys about 100 fathoms apart, 
and in about 6 fathoms of water. Midway between the two 
a boat was anchored with a copper plate hanging fore and 
aft about 10 fathoms apart, and consequently about 45 
fathoms from either end of the anchored shore wires. This 
boat represented the sea station, and, owing to the state of 
the sea, a very wet and lively one it proved ; therefore, 
taking this fact into consideration, together with the crude 
nature of the experiment, it was remarkable with what dis- 
tinctness and ease messages were passed. The last message 
sent from shore was, * Thanks : that will do ; pick up anchors 
and return.' To this the reply came from the boat, ' Under- 
stand,' and they then proceeded to carry out instructions. 
The boat employed was a wooden one, but it would have 


been much better for my purpose had it been of metal, for 
then I should have used it instead of one of the collecting 
plates, as the larger the surface of these plates the better 
the results obtained." l 

This method was secured by patent, June 7, 1887, from 
the specification of which (No. 8159) I take the following 
particulars : At the present time wherever electric telegraph 
communication is established between the shore and a light- 
house, either floating or on a rock, at a distance from the 
shore, it is effected through an insulated conductor or cable. 
Much difficulty is, however, experienced owing to the rapid 
wearing of the cable, so that it is liable to break whenever a 
storm comes on, and when, consequently, it is most required 
to be in working order. By this invention communication 
can be effected between the sending station and the distant 
point without the necessity of metallic connection between 

A in the drawing (fig. 26) is a two-conductor cable led 
from a signal-station B on shore towards the rock c. At a 
distance from the rock one of the conductors is led to a 
metallic plate D submerged on one side of the rock, and at 
such a distance from it as to be in water deep enough for it 
not to be affected by waves. The other conductor is led to 
another metallic plate E similarly submerged at a distance 
from the opposite side of the rock. F F are two submerged 
metallic plates, each opposite to the plates D and E respec- 
tively. G G are insulated conductors leading from the plates 
F F to a telephone of low resistance in the lighthouse H. 

To communicate from the shore, an interrupter or re- 
verser I and battery K are connected to the shore ends 
of the two-wire cable. The telephone in the lighthouse 
circuit then responds to the rapid makes and breaks or 
reversals of the current, so that signalling can readily be 
1 Electrician, November 2, 1888. 



carried on by the Morse alphabet. If a vibrating inter- 
rupter or reverser be used, a short or long sound in the 
telephone can be obtained by a contact key held down for 
short or long intervals. 

A more convenient way is to use two finger-keys, one of 
which by a series of teeth on its stem produces a few breaks 
or reversals of the current, whilst the other key when 
depressed produces a greater number of breaks or reversals. 

Fig. 26. 

For communicating from the lighthouse to the shore a 
battery and make-and-break apparatus are coupled to the 
insulated conductors on the rock, and a telephone to the 
shore ends. 

In the same way communication could be carried on 
from the shore to a vessel at a distance from it, if the 
vessel were in the vicinity of two submerged plates or 
anchors, each having an insulated conductor passing from 
it to the shore, and if two metallic plates were let go from 


the vessel so that these plates might be at a distance apart 
from one another. The position of the two submerged plates 
might be indicated by buoys. In this way communication 
might be effected between passing vessels and the shore, or 
between the shore and a moored lighthouse or signal-station. 

A similar result might be obtained with a single insulated 
conductor from the shore by the use of an induction appar- 
atus, the ends of the secondary coil being connected by 
insulated conductors to the submerged plates. 

An important modification of this method was subse- 
quently effected by Messrs Willoughby S. Smith & W. 
P. Granville, 1 based on the following reasoning : 

In fig. 27 A B represents an insulated conductor of any 
desired length, with ends to earth E E as shown, c is a 

Fig. 27. 

rock island on which is extended another insulated wire 
c D, with its ends also connected to earth. Now, if a 
current is caused to flow in A B, indications of it will be 
shown on a galvanometer in the circuit c D. This is Mr 
Preece's arrangement at Lavernock-Flat Holm. 

1 See their patent specification, No. 10,706, of June 4, 1892. 



Now, if we rotate the line A B round A until it assumes 
the position indicated in fig. 28, we have Messrs Smith 
& Granville's arrangement, where, owing to the proximity 

Fig. 28. 

of B to D, signalling is practicable with a small battery 

power. Thus, where the distance from B to D was 60 

yards, one Leclanche cell was found to be ample. As 

Fig. 29. 

a permanent current in A B causes a permanent deflection 
on the galvanometer in c D, this deflection cannot be pro- 
duced otherwise than by conduction. 

Again, let A B (fig. 29) represent an insulated conductor 


having its ends submerged in water (the distance between A 
and B being immaterial). Now cause a current to flow con- 
tinuously, and it will be found that the water at each end 
of the conductor is charged either positively or negatively 
(according to the direction of the current) in equipotential 
spheroids, diminishing in intensity as the distance from 
either A or B is increased. To prove this, provide a second 
circuit, connected with a galvanometer, and with its two 
ends dipping into the water. Now, it will be found that a 
current flows in the c D circuit as long as the current in A B 
is flowing ; the current in c D diminishes as c and D are 
moved farther away from B, and also diminishes to zero if 
the points c D are turned until they both lie in the same 
equipotential curve as shown by the dotted line. 

It must be well understood that although, for the sake of 
clearness, the equipotential curves are shown as planes, yet 
in a body of water they are more or less spheres extending 
symmetrically around the submerged ends of the conductor, 
and therefore it is evident from the foregoing that the 
position of c D, in relation to B, must be considered not only 
horizontally but vertically. 1 

Early in 1892 the Trinity Board placed the Needles 
Lighthouse at the disposal of the Telegraph Construction 
and Maintenance Company, so that they might prove the 
practicability of the method here described. The Needles 

1 This fact, Mr Smith thinks, fully explains Mr Preece's launch ex- 
periments (p. 150, ante). For instance, when the launch towing the 
half-mile of cable parallel to the wire on the mainland was close to the 
shore, the cable, although allowed to sink, could only do so to a very 
limited extent, and therefore still remained in a favourable position 
for picking up the earth-currents from A B (fig. 29) ; but when one 
mile from the shore, and in deep water, the cable was able to assume 
somewhat of a vertical position with the two ends brought more or 
less into the same equipotential sphere, it naturally resulted in a 
diminution or cessation of the current in the c D or launch circuit, 
and hence the absence of signals. 


Lighthouse was chosen on account of its easy access from 

In May 1892 an ordinary submarine cable was laid from 
Alum Bay to within 60 yards of the lighthouse rock, where 
it terminated, with its conductor attached to a specially con- 
structed copper mushroom anchor. An earth plate close to 
the pier allowed a circuit to be formed through the water. 
On the rock itself two strong copper conductors were placed, 
one on either side, so that they remained immersed in the 
sea at low water, thus allowing another circuit to be formed 
through the water in the vicinity of the rock. 

The telephone was first tried as the receiving instrument, 
with a rapid vibrator and Morse key in the sending circuit. 
This arrangement was afterwards abandoned, as it was not 
nearly so satisfactory as a mirror-speaking galvanometer, and 
the men, being accustomed to flag work, preferred to watch 
a light rather than listen to a telephone. The speaking 
galvanometer used is a specially constructed one, and does 
not easily get out of repair, so that, everything being once 
arranged, the men had only to keep the lamp in order. 

Messrs Smith & Granville devised a novel and strong 
form of apparatus for a " call," and by its means any number 
of bells could be rung, thus securing attention. The instru- 
ments both on rock and shore were identical, and, in actual 
work, two to three Leclanche cells were ample. 

By the means above described, communication was ob- 
tained through the gap of water 60 yards in length. This by 
no means is the limit, for it will be apparent that the gap 
distance is determined by the volume of water in the imme- 
diate neighbourhood of the rock, as well as by the sensitive- 
ness of the receiving instrument and the magnitude of the 
sending current. 

This method is well suited for coast defences. For 
instance, if a cable is laid from the shore out to sea, with its 


end anchored in a known position, then it would be easy for 
any ship, knowing the position of the submerged . end, to 
communicate with shore by simply lowering (within one or 
two hundred yards of the anchored end) an insulated wire 
having the end of its conductor attached to a small mass of 
metal to serve as "earth," the circuit being completed 
through the hull of the ship and the sea. 1 

As this method has been in practical use at the Fastnet 
Lighthouse for the last three years, the following account of 
the installation, which has been kindly supplied by Mr W. 
S. Smith, will be of interest : 

" The difficulty of maintaining electrical communication 
with outlying rock lighthouses is so great that it has become 
necessary to forego the advantages naturally attendant upon 
the use of a submarine cable laid in the ordinary way con- 
tinuously from the shore to the lighthouse, inasmuch as that 
portion of the cable which is carried up from the sea-bed to 
the rock is rapidly worn or chafed through by the combined 
action of storm and tide. By the use of the Willoughby 
Smith & Granville system of communication this difficulty 
is avoided, for the end of the cable is not landed on the 
rock at all, but terminates in close proximity thereto and 
in fairly deep undisturbed water. This system, first sug- 
gested in 1887 and practically demonstrated at the Needles 
Lighthouse in 1892, has on the recommendation of the 
Royal Commission on Lighthouse and Lightship Communi- 
cation been applied to the Fastnet, one of the most 
exposed and inaccessible rock lighthouses of the United 

" The Fastnet Rock, situated off the extreme S. W. corner 
of Ireland, is 80 feet in height and 360 feet in length, with 
a maximum width of 150 feet, and is by this system placed 

1 ' Electrician, ' September 29, 1893. See also the ' Times,' Novem- 
ber 24, 1892. 


in electrical communication with the town of Crookhaven, 
eight miles distant. 

" The shore end of the main cable, which is of ordinary 
construction, is landed at a small bay called Galley Cove, 
about one mile to the west of the Crookhaven Post Office, 
to which it is connected by means of a subterranean cable 
of similar construction having a copper conductor weighing 
107 Ib. covered with 150 Ib. of gutta-percha per nautical 
mile. The distant or sea end of the main cable terminates 
seven miles from shore, in 1 1 fathoms of water, at a spot 
about 100 feet from the Fastnet Rock ; and the end is 
securely fastened to a copper mushroom-shaped anchor 
weighing about 5 cwt., which has the double duty of serving 
electrically as an ' earth ' for the conductor, and mechanically 
as a secure anchor for the cable end. 

"The iron sheathing of the last 100 feet of the main 
cable is dispensed with, so as to prevent the possibility of 
any electrical disturbance being caused by the iron coming 
in contact with the copper of the mushroom ; and, as a sub- 
stitute, the conductor has been thickly covered with india- 
rubber, then sheathed with large copper wires, and again 
covered with india-rubber the whole being further protected 
by massive rings of toughened glass. 

"To complete the main cable circuit, a short earth line, 
about 200 yards in length, is laid from the post office into 
the haven. 

"By reference to the diagram (fig. 30) it will be seen 
that if a battery be placed at the post office, or anywhere in 
the main cable circuit, the sea becomes electrically charged 
the charge being at a maximum in the immediate vicinity 
of the mushroom, and also at the haven ' earth.' Under 
these conditions, if one end of a second circuit is inserted 
in the water anywhere near the submerged mushroom for 
instance, on the north side of the Fastnet it partakes, 



more or less, of the charge ; and if the other end of this 
second circuit is also connected to the water, but at a point 
more remote from the mushroom for instance, at the south 
side of the Fastnet then a current will flow in the second 
circuit, due to the difference in the degree of charge at the 
two ends ; and accordingly a galvanometer or other sensitive 

Fig. 30. 

instrument placed in the Fastnet circuit is affected whenever 
the post office battery is inserted in the main cable circuit, 
or, vice versa, a battery placed in the Fastnet circuit will 
affect a galvanometer at the post office. 

" In practice ten large-size Leclanche cells are used on 
the rock, the sending current being about 1*5 amperes, and 


in this case the current received on shore is equal to about 
15 of a milliampere. The received current being small, 
instruments of a fair degree of sensitiveness are required, 
and such instruments, when used in connection with cables 
having both ends direct to earth, are liable to be adversely 
affected by what are known as * earth ' and ' polarisation ' 
currents, consequently special means have been devised to 
prevent this. 

" The receiving instrument is a D'Arsonval reflecting 
galvanometer, which has been modified to meet the require- 
ments by mounting the apparatus on a vertical pivot, so 
that by means of a handle the galvanometer can be rotated 
through a portion of a circle thus enabling the zero of the 
instrument to be rapidly corrected. This facility of adjust- 
ment is necessary on account of the varying 'earth' and 
' polarisation ' currents above mentioned. 

" An entirely novel and substantial ' call ' apparatus has 
also been designed, which automatically adapts itself to any 
variation in the earth or polarisation current. It consists 
essentially of two coils moving in a magnetic field, and 
these coils are mounted one at each end of a balanced arm 
suspended at its centre and free to rotate horizontally within 
fixed limits. The normal position of the arm is midway 
between two fixed limiting stops. Any current circulating 
in the coils causes the whole suspended system to rotate 
until the arm is brought into contact with one or other of 
the stops the direction of rotation depending upon the 
direction of the current. A local circuit is thus closed, 
which releases a clockwork train connected to a torsion 
head carrying the suspending wire, and thus a counter- 
balancing twist or torsion is put into the wire, and this 
torsion slowly increases until the arm leaves the stop and 
again assumes its free position. If, however, the current 
is reversed within a period of say five or ten seconds, then 


the clockwork closes a second circuit and the electric bell is 
operated. By this arrangement, whilst the relay automatic- 
ally adjusts itself for all variations of current, the call-bell 
will only respond to definite reversals of small period and 
not to the more sluggish movements of earth-currents. It 
is evident that one or more bells can be placed in any part 
of the building. The receiving galvanometer and the * call ' 
relay have worked very satisfactorily, and any man of aver- 
age intelligence can readily be taught in two or three weeks 
to work the whole system. 

" To enable the two short cables that connect the light- 
house instruments with the water to successfully withstand 
the heavy seas that at times sweep entirely over the Fastnet, 
it has been found necessary to cut a deep ' chase ' or groove 
down the north and south faces of the rock from summit to 
near the water's edge, and to bed the cables therein by 
means of Portland cement. And since the conductors must 
make connection with the water at all states of sea and tide, 
two slanting holes 2J inches in diameter have been drilled 
through the solid rock from a little above low-water mark 
to over 20 feet below. Stout copper rods connected with 
the short cables are fitted into these holes, and serve to 
maintain connection with the water even in the roughest 
weather, and yet are absolutely protected from damage." 

Mr Granville supplies some interesting particulars as to 
the difficulties of their installation at the Fastnet. 1 " The 
rock," he says, "is always surrounded with a belt of foam, 
and no landing can be made except by means of a jib 58 
feet long not at all a pleasant proceeding. Now, here is a 
case where the Government desired to effect communication 
telegraphically, but, as had been proved by very costly ex- 
periments, it was impossible to maintain a continuous cable, 
the cable being repeatedly broken in the immediate vicinity 
1 Jour. Inst. Elec, Engs., Ko 137, p. 941. 


of the rock. This, therefore, is a case where some system 
of wireless telegraphy is absolutely necessary, but neither of 
the systems described would answer here. 1 Dr Lodge advises 
us to eschew iron, and to avoid all conducting masses. But 
the tower and all the buildings are built of boiler-plate, and 
that which is not of iron is of bronze. In fact, the rock 
itself is the only bit of non-conducting, and therefore non- 
absorbing, substance for miles around. It is very clear in a 
case of this sort and this is a typical case that it is abso- 
lutely impracticable to employ here Dr Lodge's method. 
Now we hear in regard to the method used and success- 
fully used at Lavernock, that a certain base is required, of 
perhaps half a mile, a quarter of a mile, or a mile in length ; 
and that base must bear some proportion to the distance to 
be bridged. But where can you get any such base on the 
rock 1 You could barely get a -base of 20 yards, so that 
method utterly fails. Then we come to the case suggested 
by Mr Evershed, of a coil which would be submerged round 
the rock. Well, where Would the coil be after the first 
summer's breeze, let alone after a winter gale ? Why, prob- 
ably thrown up, entangled, on the rock. A few years ago, 
during a severe gale, the glass of the lantern, 150 feet above 
sea-level, was smashed in ; and at the top of the rock, 80 
feet above the sea-level, the men dare not, during a winter's 
gale, leave the shelter of the hut for a moment, for, as they 
said and I can well believe it they would be swept off 
like flies. This is a practical point, and therefore one I am 
glad to bring to the notice of the Institution ; and, I repeat, 
if wireless telegraphy is to be of use, it must be of use for 
these exceptional cases." 

Strange as it may seem, we have been using, on occasion, 
wireless telegraphy of this form for very many years without 

1 I.e., those advocated by Professor Lodge and Mr Sydney Ever- 
shed. See 'Jour. Inst. Elec. Engs.,' No. 137, pp. 799, 852. 


recognising the fact. Every time in ordinary telegraphy 
that we " work through a break," as telegraphists say, we 
are doing it. An early instance of the kind is described in 
the old 'Electrician,' January 9 and 23, 1863. Many years 
ago, in Persia, the author has often worked with the ordinary 
Morse apparatus through breaks where the wire has been 
broken in one or more places, with the ends lying many 
yards apart on damp ground, or buried in snow-drifts. As 
the result of his experiences in such cases the following 
departmental order was issued by the Director, Persian 
Telegraphs, as far back as November 2, 1881 : "In cases 
of total interruption of all wires, it is believed that com- 
munication may in most cases be kept up by means of 
telephones. Please issue following instructions : Fifteen 
minutes after the disappearance of the corresponding station, 
join all three wires to one instrument at the commutator. 
Disconnect the relay wire from the key of said instrument, 
and in its stead connect one side of telephone, other side of 
which is put to earth. Now call corresponding station 
slowly -by key, listening at telephone for reply after each 
call. Should no reply be received, or should signals be too 
weak, try each wire separately, and combined with another, 
until an arrangement is arrived at which will give the best 
signals." The Cardew sounder or buzzer has in recent years 
been added, and with very good results. It will thus be 
seen that Mr Willoughby Smith's plan is really an old 
friend in a new guise. 1 

1 In 1896 Mr A. C. Brown, of whose work in wireless telegraphy we 
have already spoken (p. 104, ante), revived the early proposals of 
Gauss (p. 3), Lindsay (p. 20), Highton (p, 40), and Bering (p. 48), 
re the use of bare wire or badly insulated cables in connection with 
interrupters and telephones. He also applies his method to cases 
where the continuity of the cable is broken. "Providing the ends 
remain anywhere in proximity under the water, communication can 
usually be kept up, the telephone receivers used in this way being so 



" Even the lightning-elf, who rives the oak 
And barbs the tempest, shall bow to that yoke, 
And be its messenger to run." 

Supples Dampier's Dream. 

We now come to the crowning work of Mr Marconi in 
wireless telegraphy ; but before describing this method it 
will be desirable to make ourselves acquainted with the 
principles involved in the special apparatus which he em- 
ploys, and which differentiates his system from all those 
that have hitherto occupied us. For this we need only go 
back a few years, and make a rapid survey of the epoch- 
marking discoveries of a young German philosopher, Hein- 
rich Hertz. 1 

To properly appreciate the work of Hertz we must carry 
our minds back two hundred years, to the time when New- 
ton made known to the world the law of universal gravita- 
tion. Here, in the struggle between jSTewtonianism.and the 
dying Cartesian doctrine, we have the battle-royal between 
the rival theories of action-at-a-distance and action-by-contact. 
The victory was to the former for a time ; and in the hands 

exceedingly sensitive that they will respond to the very minute traces 
of current picked up by the broken end on the receiving side from 
that which is spreading out through the water in all directions from 
the broken end on the sending side." (See Mr Brown's patent specifi- 
cation, No. 30,123, of December 31, 1896.) 

Eecently he has been successful in bridging over in this way a gap 
in one of the Atlantic cables ; but in this he has done nothing more 
than the present writer did in 1881, and Mr Willoughby Smith in 

1 Hertz was born in Hamburg. February 22, 1857, and died in 
Bonn, January 1, 1894. For interesting notices of his all too brief 
life, see, inter alia, the 'Electrician,' vol. xxxiii. pp. 272, 299, 332, 
and 415. 


of Bernoulli!, and, subsequently, of Boscovich, the doctrines 
of Newtonianism were carried far beyond the doctrines of 
the individual Newton. In fact, Newton expressed himself 
as being opposed to the notion of matter acting where it is 
not; though, as we see by his support of the emission 
theory of light, he was not prepared to accept the notion 
of a luminiferous ether. Newton, however, suggested that 
gravitation might be explained as being due to a diminution 
of pressure in a fluid filling space. Thus the doctrine of 
an empty space, requiring the infinitely rapid propagation 
of a distance-action, held the field, and was recognised by 
scientists of the eighteenth century as the only plausible 

History repeats itself ; and again the battle-royal was 
fought, this time, early in the nineteenth century, in favour 
of the ether hypothesis ; and action-at-a-distance was mort- 
ally wounded. Before the phenomena of interference of 
light and the magnetic and electro-static researches of Fara- 
day, both the idea of empty space action and that of the 
emission of light failed ; and the propagation of force 
through the ether, and of light by vibratory conditions of 
the ether, came to be held as necessary doctrines. Later 
still, 1 Maxwell assumed the existence of, and investigated 
the state of, stress in a medium through which electro- 
magnetic action is propagated. The mathematical theory 
which he deduced gives a set of equations which are identi- 
cal in form with the equations of motion of an infinite elastic 
solid ; and, on this theory, the rate of propagation of a 
disturbance is equal to the ratio of the electro-magnetic 

1 The date usually assigned to Clerk-Maxwell's electro-magnetic 
theory of light is 1864 ; but his first communication on the subject 
to the Royal Society was in 1867 ; while the full development only 
appeared in his great work, ' Electricity and Magnetism,' which was 
published in 1873. 


and electro-static units. The experimental determination 
by Maxwell and others, that this ratio is a number equal to 
the velocity of light in ether in centimetres per second, is a 
fact which gave immense strength to the Maxwellian hypo- 
thesis of identity of the light and electro-magnetic media. 
But, although this is the case, the Maxwellian hypothesis, 
even when taken in conjunction with the experimental 
support which he educed for it, fell far short of being a 
complete demonstration of the identity of luminous and 
electro-magnetic propagation. 1 

To the genius of Hertz we owe this demonstration. One 
of the most important consequences of Maxwell's theory 
was that disturbances of electrical equilibrium produced at 
any place must be propagated as waves through space, with 
a velocity equal to that of light. If this propagation was 
to be traced through the small space inside a laboratory, the 
disturbances must be rapid, and if a definite effect was to be 
observed, they must follow each other at regular intervals ; 
in other words, periodical disturbances or oscillations of 
extreme rapidity must be set up, so that the corresponding 
wave-length, taking into account the extraordinarily high 
velocity of propagation (186,000 miles per second), may be 
only a few inches, or at most feet. Hertz was led to an ex- 
periment which satisfied these conditions, and thus supplied 
the experimental proof which Maxwell and his school knew 
must come sooner or later. 

The oscillatory nature of the discharge of a Leyden jar, 
under certain conditions, was theoretically deduced by Von 
Helmholtz in 1847 ; its mathematical demonstration was 
given by Lord Kelvin in 1853; and it was experimentally 
verified by Feddersen in 1859. When a Leyden jar, or a 
condenser, of an inductive capacity K, is discharged through 
a circuit of resistance K and self-induction L, the result is an 
1 Lord Kelvin's Address, Royal Society, November 30, 1893. 


instantaneous flow, or a series of oscillations, according as R 
is greater, or less, than 2 /= ; and in the latter case the 
oscillatory period or amplitude is given in the equation 

where TT is the constant 3-1415 ('Phil. Trans.,' June 1853). 1 
In his collected papers 2 Hertz tells us that his interest in 
the study of electrical oscillations was originally awakened 
by the announcement of the Berlin prize of 1879, which 
was to be awarded for an experimental proof of a relation 
between electro-dynamic forces and dielectric polarisation in 
insulators. At the suggestion of his master and friend, 
Von Helmholtz, the young philosopher took up the inquiry, 
but soon discovered that the then known oscillations were too 
slow to offer any promise of success, and he gave up the 
immediate research ; but from that time he was always on 
the look-out for phenomena in any way connected with the 
subject. Consequently, he immediately recognised the im- 
portance of a casual observation which in itself and at 
another time might have been considered as too trivial for 
further notice. In the collection of physical apparatus at 
Karlsruhe he found an old pair of so-called Riess's or 
Knochenhauer's spirals short flat coils of insulated wire, 
with the turns all in the same plane (IProf. Henry's 
spirals). While performing some experiments with them at 
a lecture he was giving, he noticed that the discharge of a 
very small Leyden jar, or of a small induction coil, passed 
through the one was able to excite induced currents in the 

1 For a concise exposition of the theory of electrical oscillations, 
see Prof. Edser's paper, 'Electrical Engineer,' June 3, 1898, and fol- 
lowing numbers. 

2 'Electric Waves,' London, 1893. For an interesting account of 
pre-Hertzian observations, see Lodge's 'The Work of Hertz,' p. 61. 
Also Appendix D. of this work. 


other, provided that a small spark-gap was made in the 
circuit of the first spiral. Thus was made the all-important 
discovery of the " effective spark-gap " which started Hertz 
on the road of his marvellous investigations. 

A very little consideration of this phenomenon enabled 
him, even at this early stage, to lay down the following 
propositions : 

1. If we allow a condenser, such as a Leyden jar, of 
small capacity, to discharge through a short and simple 
circuit with a spark-gap of suitable length, we obtain a 
sharply denned discharge of very short duration, which is 
the long-sought-for sudden disturbance of electrical equili- 
brium the exciter of electrical vibrations. 

2. Such vibrations are capable of exciting in another 
circuit of like form resonance effects of such intensity as to 
be evident even when the two circuits are separated by 
considerable distances. In this second circuit Hertz had 
found the long-sought-for detector of electric waves. 

With the exciter to originate electric waves and the 
detector to make them evident at a distance, all the pheno- 

Fig. 31. 

mena of light were, one after another, reproduced in cor- 
responding electro-magnetic effects, and the identity of light 
and electricity was completely demonstrated. 1 

In his paper " On very Eapid Electric Oscillations," Hertz 

1 See Appendix A for a clear exposition of the views regarding the 
relation of the two before and after Hertz. 


occupied himself with some of these phenomena. As an 
exciter he used wire rectangles, or simple rods (fig. 31) to 
the ends of which metallic cylinders or spheres were con- 
nected, the continuity being broken in the middle where 
the ends were provided with small spherical knobs between 
which the sparks passed. The exciter was charged by an 
ordinary Euhmkorff induction coil of small size. 

The detector was mostly a simple rectangle or circle of 
wire (fig. 32), also provided with a spark-gap. When 
vibrations are set up in the detector 
and sparks pass across the gap, the 
greater length of these sparks in- 
dicates the greater intensity of the 
received wave impacts. When, there- 
fore, the dimensions of the detector 
are so adjusted as to give the maximum 
sparks with a given exciter the two 
circuits are said to be in resonance, or to be electrically 
tuned. 1 

In the course of his experiments on electric resonance, 
Hertz observed a phenomenon which for a time was inex- 
plicable. It was seen that the length and brightness of the 
sparks at the detector were greatly modified by the sparks 
given off at the exciter. If the latter were visible from the 
detector spark-gap the sparks given off there were small and 
hardly perceptible, but became larger and brighter as soon 

1 Fortunately this condition of resonance or syntony is not essential 
to the excitement of sparks, else wireless telegraphy by Hertzian waves 
would not be so advanced as it is to-day. Thus, when a good exciter 
is in action it will cause little sparks between any conducting body in 
its vicinity and a wire held in the hand and brought near to the body, 
showing that the influence of the exciter extends to all conducting 
bodies, and not merely to those which are tuned to it. Of course it 
still holds good that, cceteris parilus, the maximum effect is obtained 
with resonance. 


as a screen was placed between the two instruments. By 
carefully thought-out experiments he showed that this 
singular action was due solely to the presence of ultra-violet 
light, thus furnishing a proof of the connection between 
light and electricity. 1 

Having made himself familiar with the phenomena of 
electrical resonance, Hertz went on to study the propagation 
of electric vibrations through space the most difficult, as 
it is probably the most important, of all his researches. 
The results he gave to the world in 1888, in his paper 
" On the Action of a Eectilinear Electric Oscillation on a 
Neighbouring Circuit." When sparks pass rapidly at the 
exciter electric surgings occur, and we have a rectilinear 
oscillation which radiates out into surrounding space. The 
detectors, whose spark-gaps were adjustable by means of a 
micrometer screw, were brought into all kinds of positions 
with respect to the exciter, and the effects were studied and 
measured. These effects were very different at different 
points and in the different positions of the detector. In 
short, they were found to obey a law of radiation which was 
none other than the corresponding law in optics. 

In his paper, " On the Velocity of Propagation of Electro- 
dynamic Actions," he gave experimental proof of the hitherto 
theoretical fact that the velocity of electric waves in air was 
the same as that of light, whereas the velocity in wires 
was found to be much smaller in the ratio of 4 to 7. For 
the moment he was puzzled by this result : he suspected an 
error in the calculations, or in the conditions of the experi- 
ment, but and here he showed himself the true philosopher 
he did not hesitate to publish the actual results, trusting 

1 Prof. K. Zickler has recently proposed to use this property for 
telegraphy. He has succeeded on a small scale, and thinks that with 
a 25-ampere lamp and suitable reflectors the effect would be possible 
over several kilometres. 'Elektrische Zeitung,' July 1898. 


to the future to correct or explain the discrepancy. The 
explanation was soon forthcoming. Messrs E. Sarasin and 
L. de la Rive of Geneva took up the puzzle, and ended by 
showing that the deviations from theory were caused simply 
by the walls of Hertz's laboratory, which reflected the 
electric waves impinging on them, so causing interferences 
in the observations. When these investigators repeated 
the Hertzian experiment with larger apparatus, and on a 
larger scale, as they were able to do in the large turbine 
hall of the Geneva Waterworks, they found the rate of prop- 
agation to be the same along wires as in air. 1 

In his paper, " On Electro-dynamic Waves and their Re- 
flection," Hertz further developed this point, and showed the 
existence of these waves in free space. Opposite the exciter 
a large screen of zinc plate, 8 feet square, was suspended on 
the wall ; the electric waves emitted from the exciter were 
reflected from the plate, and on meeting the direct waves 
interference phenomena were produced, consisting of sta- 
tionary waves with nodes and loops. When, therefore, 
Hertz moved the circle of wire which served as a detector 
to and fro between the screen and the exciter, the sparks in 
the detector circuit disappeared at certain points, reappeared 
at other points, disappeared again, and so on. Thus there 
was found a periodically alternating effect corresponding to 
nodes and loops of electric radiation, showing clearly that in 
this case also the radiation was of an undulatory character, 
and the velocity of its propagation finite. 

In a paper, " On the Propagation of Electric Waves along 
Wires," March 1889, Hertz shows that alternating currents 
or oscillations of very high frequencies, as one hundred 
million per second, are confined to the surface of the con- 
ductor along which they are propagated, and do not penetrate 

1 ' Comptes Rendus,' March 31, 1891, and December 26, 1892. See 
also the 'Electrician,' vol. xxvi. p. 701, and vol. xxx. p. 270. 


the mass. 1 This is a very important experimental proof of 
Poynting's theory concerning electric currents, which he had 
deduced from the work of Faraday and Maxwell. Accord- 
ing to this theory, the electric force which we call the 
current is in nowise produced in the wire, but under all 
circumstances enters from without, and spreads itself in the 
metal comparatively slowly, and according to similar laws as 
govern changes of temperature in a conductor of heat. If 
the electric force outside the wire is very rapidly altering 
in direction or oscillating, the effect will only enter to a 
small depth in the wire ; the slower the alterations occur, 
the deeper will the effect penetrate, until finally, when the 
changes follow one another infinitely slowly, the electric 
effect occupies the whole mass of the wire with uniform 
density, giving us the phenomenon of the so-called current. 
Reviewing his experiments on this subject, Hertz says : 
" A difference will be noticed between the views here put 
forward and the usual theory. According to the latter, con- 
ductors are represented as those bodies which alone take 
part in the propagation of electric disturbances; non-con- 
ductors are the bodies which oppose this propagation. Ac- 
cording to our view, on the contrary, all transmission of 
electrical disturbances is brought about by non-conductors ; 
conductors oppose a great resistance to any rapid changes in 
this transmission. One might almost be inclined to main- 
tain that conductors and non-conductors should, on this 
theory, have their names interchanged. However, such a 
paradox only arises because one does not specify the kind of 

1 It should be stated here that long ago Prof. Henry, the Faraday 
of America, held the same views, and proved them, too, by an experi- 
ment which is strangely like one of Hertz's, though, of course, he did 
not explain them as Hertz does. Henry's views are given clearly in 
two letters addressed to Prof. Kedzie of Lansing, Michigan, in 1876. 
Being of historical interest, as well as of practical value, I give them 
entire in Appendix B. 


conduction or non-conduction considered. Undoubtedly 
metals are non-conductors of electric force, and just for this 
reason they compel it under certain circumstances to remain 
concentrated instead of becoming dissipated ; and thus they 
become conductors of the apparent source of these forces, 
electricity, to which the usual terminology has reference." l 
In the course of his experiments Hertz had succeeded in 
producing very short electric waves of 30 centimetres in 
length, the oscillations corresponding to which could be 
collected by a concave cylindrical mirror and concentrated 
into a single beam of electric radiation. According to 
Maxwell's theory of light, such a beam must behave like 
a beam of light, and that this is the case Hertz abundantly 
proved in his next paper, " On Electric Eadiation." He 
showed how such radiation was propagated in straight lines 
like light ; that it could not pass through metals, but was 
reflected by them ; that, on the other hand, it was able to 
penetrate wooden doors and stone walls. He also proved, 
by setting up metallic screens, that a space existed behind 
them in which no electric action could be detected, thus 
producing electric shadows ; and, by passing the electric 
rays through a wire grating, he was able to polarise them, 
just as light is polarised by passage through a Nicol prism. 
Perhaps the most striking experiment of all in this field was 
his last one, in which he directed the ray on to a large pitch 
prism weighing 12 cwts. : the ray was deflected, being, in 
fact, refracted like a ray of light in a glass prism. 

1 As this is a matter of some complexity to all who, like myself, 
belong to the old way of thinking the ancien regime and as, more- 
over, it is of great practical importance, especially as regards the 
proper construction of lightning protectors, and the supply mains of 
electric light and power, I have thought it useful to give in Appendix 
B some extracts, which I hope will make the new views intelligible to 
the ordinary reader. Lodge's ' Modern Views of Electricity ' should 
also be consulted. 


Thus he gave to the experimental demonstration of Max- 
well's electro-magnetic theory of light its finishing touch, 
and the edifice was now complete. Hertz's marvellous 
researches were presented in succession, as rapid and sur- 
prising almost as the sparks with which he dealt, to the 
Berlin Academy of Sciences, between November 10, 1887, 
and December 13, 1889. They were collected and pub- 
lished in book form, in 1893, under the title of 'Electric 
Waves ' (English translation edited by Prof. D. E. Jones), 
to which the reader is jeferred for further information. 

Here it will suffice, in conclusion, to briefly sum up the 
chief results of these epoch-making investigations. In the 
first place, Hertz has freed us from the bondage of the old 
theory of action-at-a-distance ; and as regards electric and 
magnetic effects, he has shown that they are propagated 
through the ether which fills all space with finite velocity. 
The mysterious darkness which surrounded those strange 
distance-actions that something can act where it is not 
has now been cleared away. Further, the identity of the 
form of energy in the case of two powerful agents in nature 
has been conclusively established ; light and electrical radia- 
tion are essentially the same, different manifestations of the 
same processes, and so the old elastic-solid theory of optics 
is resolved into an electro-magnetic theory. The velocity of 
propagation of light is the same as that of electro-magnetic 
waves, and these in turn obey all the laws of optics. The 
scope of optics is thus enormously widened ; to the ultra- 
violet, visible, and infra-red rays, with their wave-lengths 
of thousandths of a millimetre, are now to be added, lower 
down the scale, electro-magnetic waves, producible in any 
length from fractions of an inch to thousands of miles. 

Hertz's ordinary waves were many metres long, and he 
does not appear to have ever worked with waves of less 
than 30 centimetres. Righi, however, by employing ex- 


citers with small spheres, obtained waves of 2 '5 centimetres; 
while Prof. Chunder Boze of Calcutta, using little pellets of 
platinum, was able to produce them of only 6 millimetres ! 
The smaller the pellets the shorter the electric waves, until 
we come in imagination to the pellet of the ultimate atom, 
whose waves should closely approximate to light. 

The following table compares approximately some of the 
known vibrations in ether and air : 

Ether vibrations per second 

billions (?) = Rontgen rays. 

10,000 (?) = Actinic 

8,000 it = Violet ,, 

5,500 M = Green .. 

4,000 u = Red 

2,800 n = Infrared 

1,000 to 2,000 = Radiant heat. 

50 thousands to 2,000 billions = Hertzian waves. 

Air vibrations per second 

33,000 = Highest audible note. 

4,000 = Highest musical note. 

2,000 = Highest soprano. 

150 to 500 = Ordinary voice. 

32 = Lowest musical note. 

16 = n audible u 

In another direction we owe much to Hertz's investiga- 
tions ; we are brought nearer to a solution of the question, 
What is electricity 1 He shows us that it is not an entity 
of the nature of a fluid as in the older theories ; what we 
wished to explain by assuming an electricity is in reality 
nothing but a condition of a medium which, although 
hypothetical, manifests itself by its effects namely, the 
ether which fills all space and permeates all matter. 1 

1 Our account of Hertz's investigations is chiefly drawn from Prof. 
Ebert's paper in the 'Electrician,' vol. xxxiii. pp. 333-335. 


The work of Hertz was immediately taken up, and is now 
being carried on (doubtless towards fresh conquests, for 
there is no finality in science) by a whole army of investi- 
gators, of whom we need only mention a few as Lodge, 
Eighi, Branly, Sarasin, and de la Rive whose discoveries, 
especially as regards the exciter and detector, more imme- 
diately concern us in this history. 

The exciter of Hertz, although sufficing for his special 
purposes, had the disadvantage that the sparks in a short 
time oxidised the little knobs and roughened their surfaces, 
which made their action irregular and necessitated their 
frequent polishing. Messrs Sarasin & de la Rive of Geneva 
obviated this difficulty by placing the knobs in a vessel con- 
taining olive-oil. The effect of this arrangement was at 
once to augment the sparks at the detector, so that when it 
was placed close to the exciter the sparks were a perfect 
blaze ; and at 10 metres' distance, with detectors of large 
diameter ('75 to 1 metre), they were still very bright and 
visible from afar. It is true that here, too, the oil carbon- 
ises in time and loses its transparency ; but if a considerable 
quantity, as two or three litres, be employed, there is no 
perceptible heating, and the intensity of the sparks is hardly 
altered, even after half an hour's continuous working. Prof. 
Righi substituted vaseline-oil, made suitably thick by the ad- 
dition of solid vaseline. His exciter is composed of two metal 
balls, each set in an ebonite frame ; a parchment envelope 
connects these frames and contains the oil which thus fills 
the spark-gap. Righi attributes the increased efficiency of 
his exciter (1) to the heightening effect which a cushion of 
(insulating) liquid seems to have on the electric potential 
which gives rise to the sparks a sort of (to adopt an ex- 
pressive French phrase) reculant pour mieux sauter; and 
(2) to some sort of regularising effect making their produc- 
tion more uniform. Like Sarasin and de la Rive, he found 


that the use of vaseline obviated the necessity of frequent 
cleaning of the knobs, for even after long usage, when the 
liquid had become black and a deposit of carbon had formed 
on the opposing surfaces, the apparatus continued to work 
satisfactorily. Kighi also found that solid knobs gave 
better results than hollow ones, the oscillations in the former 
case being perceptible in the detector at nearly double the 
distance attained in the latter case. 

The detector usually employed by Hertz consisted of a 
metal wire bent into a rectangle or a circle (see fig. 32), and 
terminated by two little knobs between which the sparks 
played. But this form is not obligatory : any two distinct 
conducting surfaces separated by a spark-gap will serve 
equally well. Many kinds of detectors have been em- 
ployed, but in this place we need only concern ourselves 
with those of the microphonic order, which alone enter into 
the construction of the Marconi system of telegraphy. 1 

Just mentioning the well-known electrical behaviour of 
selenium under the action of light; the fact observed by 
Prof. Minchin that his delicate "impulsion-cells" were 
affected by Hertzian waves ; the Righi detector, consisting 
of thin bands of quicksilver (as used for mirrors) rendered 
discontinuous by cross-lines lightly traced with a diamond ; 
and the original Lodge " coherer," consisting of a metallic 
point lightly resting on a metal plate, 2 we come to the 
special form known as Branly's detector, or, as he prefers to 
call it, the radio-conductor. 

1 For other forms of detectors, based on physiological, chemical, 
electrical, thermal, and mechanical principles, see Lodge's ' The Work 
of Hertz and his Successors,' pp. 25, 56. 

2 For the first suggestions of Lodge's detector see his paper, " On 
Lightning - Guards for Telegraphic Purposes," 'Jour. Inst. Elec. 
Engs.,' vol. xix. pp. 352-354. Even before this the learned professor 
succeeded in detecting electric waves by means of a telephone, ' Jour. 
Inst. Elec. Engs.,' vol. xviii. p. 405. 


The observance of the phenomenon manifested in Branly's 
detector goes back much further than is usually supposed. 
Mr S. A. Varley was, I believe, the first to notice it, and as 
long ago as 1866 he applied it in the construction of a 
lightning protector for telegraph apparatus. 

In his paper read before the British Association (Liverpool 
meeting, 1870), he says: 

"The author, when experimenting with electric currents of 
varying degrees of tension, had observed the very great resist- 
ance which a loose mass of dust composed even of conducting 
matter will oppose to electric currents of moderate tension. 

" With a tension of, say, fifty Daniell cells, no appreciable 
quantity will pass across the dust of blacklead or fine char- 
coal powder loosely arranged, even when the battery poles 
are approached very near to one another. 

" If the tension be increased to, say, two or three hundred 
cells, the particles arrange themselves by electrical attraction 
close to one another, making good electrical contact, and 
forming a channel or bridge through which the electric cur- 
rent freely passes. 

" When the tension was still further increased to six or 
seven hundred cells the author found the electricity would 
pass from one pole to the other through a considerable in- 
terval of the ordinary dust which we get in our rooms, and 
which is chiefly composed of minute particles of silica and 
alumina mixed with more or less carbonaceous and earthy 

"Incandescent matter offers a very free passage to electrical 
discharge, as is indicated by the following experiments. The 
author placed masses of powdered blacklead and powdered 
wood charcoal in two small crucibles ; no current would pass 
through these masses whilst they were cold, however close 
the poles were approached, without actually touching. The 
battery employed in this experiment was only twelve cells. 


"The crucibles were then heated to a red heat, and elec- 
tricity freely passed through the heated powder ; and on 
testing the resistance opposed by the heated particles, placing 
the poles 1 inch apart, and employing only six cells, the 
average resistance opposed by the blacklead was only four 
British Association units, and that opposed by the wood 
charcoal five units. The average resistance of a needle 
telegraph coil may be taken at 300 units, or ohms as they 
are now termed. 

" These observations go to show that an interval of dust 
separating two metallic conductors opposes practically a de- 
creasing resistance to an increasing electrical tension, and 
that incandescent particles of carbon oppose about -g^th 
part of the resistance opposed by a needle telegraph coil. 
Eeasoning upon these data, the author was led to construct 
what he terms a 'lightning-bridge,' which he constructs in 
the following way : 

" Two thick metal conductors terminating in points are 
inserted usually in a piece of wood. These points 

approach one another within 
about -iV^i of an inch in a 
chamber cut in the middle of 
the wood. 

" This bridge is placed in 
the electric circuit in the most 
direct course which the light- 
ning can take, as shown in 
the diagram (fig. 33), and the 
space separating the two points 
33 is filled loosely with powder, 

which is placed in the chamber, 

and surrounds and covers the extremities of the pointed 

" The powder employed consists of carbon (a conductor) 


and a non-conducting substance in a minute state of division. 
The lightning finds in its direct path a bridge of powder, 
consisting of particles of conducting matter in close proximity 
to one another ; it connects these under the influence of the 
discharge, and throws the particles into a highly incandescent 
state. Incandescent matter, as has been already demon- 
strated, offers a very free passage to electricity, and so the 
lightning discharge finds an easier passage across the heated 
matter than through the coils. 

" The reason a powder consisting entirely or chiefly of 
conducting matter cannot be safely employed is that, 
although in the ordinary conditions of things it would be 
found to oppose a practically infinite resistance to the 
passage of electricity of the tension of ordinary working 
currents, when a high tension discharge occurs the particles 
under the influence of the discharge will generally be found 
to arrange themselves so closely as to make a conducting 
connection between the two points of the lightning-bridge. 
This can be experimentally demonstrated by allowing the 
secondary currents developed by a Ruhmkorff's coil to spark 
through a loose mass of blacklead. 

" The crucial test, however, is the behaviour of the bridge 
in practice. 

" These lightning-bridges have been in use since January 
1866. At the present time there are upwards of one 
thousand doing duty in this country alone, and not a single 
case has occurred of a coil being fused when protected by 

" It is only right, however, to mention that three cases, 
but three cases only, have occurred where connection was 
made under the influence of electrical discharge between 
the two metallic points in the bridge. 

"The protectors in which this occurred were amongst 
those first constructed, in which a larger proportion of con- 



ducting matter was employed than the inventor now adopts. 
The points also in those first constructed were approached 
to -g^th of an inch from one another ; and the author has no 
doubt, from an examination of the bridges afterwards, that 
under the influence of a high tension discharge connection 
was made between the two metallic points by a bridge of 
conducting matter, arranged closely together, and if the 
instruments had been shaken to loosen the powder, all would 
have been put right. In one of these three cases and it 
was the only one in which the author was supplied with 
the details he ascertained that the protector was attached 
to a needle telegraph, having the ordinary magnetic needles 
made of tempered steel magnetised ; and on the removal of 
the bridge after the discharge, so completely had the elec- 
tricity been carried away by the bridge, that the magnet- 
ism of the magnetic needle was found* not to. have been 
affected." * 

In the little-known researches of the Italian professor, 
Calzecchi-Onesti, we find this curious phenomenon again 
cropping up. In 1884-85 Prof. Calzecchi-Onesti found that 
copper filings heaped between two plates of brass were 
conductors or non-conductors of electricity according to the 
degree of heaping, and that in the latter case they could be 
made conductors under the influence of induction. Fig. 34 
illustrates his experiment. In the circuit of a small battery 
A he placed a telephone B, a galvanometer c, and two brass 
plates D E, separated by the copper filings. So long as the 

1 Mr Preece tells us the arrangement acted well, but was subject to 
what we now call coherence, which rendered the cure more trouble- 
some than the disease, and its use had to be abandoned. Mr Preece 
also says that the same action is very common in granulated carbon 
microphones like Runnings', and shaking has to be resorted to to de- 
cohere the carbon particles to their normal state. But here the 
coherence is only partially, if at all, an electrical effect, being chiefly, 
if not entirely, due to mechanical pressure. 



short-circuit arrangement F (a wire dipping into mercury) was 
open, the galvanometer showed traces of a very feeble current 
across the filings ; but, on dipping the wire for a moment 
into the mercury and then withdrawing it, a sharp click is 
heard in the telephone and the galvanometer indicates the 
passing of a strong current, showing that the filings must 
now be conductors. This change he traced to the induced 

Fig. 34. 

current of the telephone coil (the extra-current direct) at the 
moment of opening the short-circuit. He repeated this 
experiment with various powders or filings of metal, and 
ended by showing that some of them became conductors 
under the influence of a very feeble spark, while others 
became so only after being subjected to strong sparks as 
from an electrical machine. 

These important observations were published in 'II 
Nuovo Cimento,' 1884, p. 58, 1 but attracted no attention ; 
and it was only after Prof. E. Branly, of the Catholic Uni- 
versity of Paris, had published his results in 1890 that the 
earlier discoveries of Yarley and Onesti came to be remem- 
bered and appreciated at their proper value. 

1 See also 'Jour. Inst. Elec. Engs.,' vol. xvi. p. 156. 


Prof. Branly's investigations are very clearly described in 
'La Lumiere Electrique, May and June 1S91.' 1 As this 
now classic paper deals with facts which are at the very 
foundation of the Marconi system, I give some extracts 
from it in Appendix C. Here, therefore, I need only say 
that Branly verified and extended Calzecchi-Onesti's obser- 
vations, and made the further (and for our purpose vital) 
discovery that the conducting power, imparted to filings by 
electric discharges in their vicinity, can at once be destroyed 
by simply shaking or tapping them. 

The Branly detector, as constructed by Prof. Lodge, is 
shown in fig. 35. It consists of an ebonite or glass tube 

Fig. 35. 

about 7 inches long, half-an-inch outer diameter, and fitted 
at the ends with copper pistons, which can be regulated to 
press on the filings with any required degree of pressure. 
To bring back the filings to their normal non-conducting 
state, Lodge applied to the tube a mechanical tapper, worked 
either by clockwork or by a trembling electrical mechanism. 2 
These, then, the exciters and the detectors of Hertzian 
waves, are the bricks and mortar, so to speak, of the Marconi 
system, and it now only remains to see how they have been 
shaped and put together to produce a telegraph without 
connecting wires, which is the realisation of the dream of 

1 See also an abstract in the ' Electrician,' vol. xxvii. pp. 221, 448. 

2 Dr Rupp of Stuttgard has proposed to suppress the tapper and to 
effect decoherence by making the detector revolve on its axis. See 
' Elektrotechnische Zeitschrift,' April 14, 1898, or ' Electrical Review,' 
April 22, 1898. 


Steinheil in 1838. And, first, we must notice two or three 
applications, or suggested applications, which preceded the 
announcement of Marconi's invention. We do so without 
in the least meaning to detract one iota from the merit due 
to the young Irish-Italian inventor, 1 for we believe the idea 
was entirely original with him, and was unprompted by any 
suggestions from outside. The history of the applications 
of science to art shows us that these applications often occur 
simultaneously to several persons, and it is, therefore, not 
strange that such is the case in the present instance. 

Sir William Crookes, the eminent chemist and elec- 
trician, was, I believe, the first to distinctly foresee the 
applicability of Hertzian waves to practical telegraphy. In 
a very interesting paper on "Some Possibilities of Elec- 
tricity," 2 he gives us the following marvellous forecast of 
the Marconi system: 

" Rays of light will not pierce through a wall, nor, as we 
know only too well, through a London fog; but electrical 
vibrations of a yard or more in wave-length will easily 
pierce such media, which to them will be transparent. Here 
is revealed the bewildering possibility of telegraphy without 
wires, posts, cables, or any of our present costly appliances. 
Granted a few reasonable postulates, the whole thing comes 
well within the realms of possible fulfilment. At present 
experimentalists are able to generate electric waves of any 
desired length, and to keep up a succession of such waves 
radiating into space in all directions. It is possible, too, 

1 Guglielmo Marconi was born in Marzabotto, near Bologna, 25th 
April 1874, and was educated at Leghorn, and at the Bologna Uni- 
versity, where he was a sedulous attendant at the lectures of Prof. A. 

2 Fortnightly Review, February 1892, p. 173. Prof. Lodge has since 
kindly pointed out to me that about 1890 Prof. R. Threlfall of Sydney, 
N.S. Wales, threw out a suggestion of the same kind at a meeting of 
the Australasian Association for the Advancement of Science. 


with some of these rays, if not with all, to refract them 
through suitably shaped bodies acting as lenses, and so to 
direct a sheaf of rays in any given direction. Also an ex- 
perimentalist at a distance can receive some, if not all, of 
these rays on a properly constituted instrument, and by con- 
certed signals messages in the Morse code can thus pass 
from one operator to another. 

" What remains to be discovered is firstly, simpler and 
more certain means of generating electrical rays of any 
desired wave-length, from the shortest, say a few feet, which 
will easily pass through buildings and fogs, to those long 
waves whose lengths are measured by tens, hundreds, and 
thousands of miles ; secondly, more delicate receivers which 
will respond to wave-lengths between certain defined limits 
and be silent to all others ; and thirdly, means of darting 
the sheaf of rays in any desired direction, whether by lenses 
or reflectors, by the help of which the sensitiveness of the 
receiver (apparently the most difficult of the problems to be 
solved) would not need to be so delicate as when the rays 
to be picked up are simply radiating into space, and fading 
away according to the law of inverse squares. . . . 

"At first sight an objection to this plan would be its 
want of secrecy. Assuming that the correspondents were a 
mile apart, the transmitter would send out the waves in all 
directions, and it would therefore be possible for any one 
living within a mile of the sender to receive the communica- 
tion. This could be got over in two ways. If the exact 
position of both sending and receiving instruments were 
known, the rays could be concentrated with more or less 
exactness on the receiver. If, however, the sender and 
receiver were moving about, so that the lens device could 
not be adopted, the correspondents must attune their instru- 
ments to a definite wave-length, say, for example, 50 yards. 
I assume here that the progress of discovery would give 


instruments capable of adjustment by turning a screw, or 
altering the length of a wire, so as to become receptive of 
waves of any preconcerted length. Thus, when adjusted to 
50-yard waves, the transmitter might emit, and the receiver 
respond to, rays varying between 45 and 55 yards, and be 
silent to all others. Considering that there would be the 
whole range of waves to choose from, varying from a few 
feet to several thousand miles, there would be sufficient 
secrecy, for the most inveterate curiosity would surely recoil 
from the task of passing in review all the millions of pos- 
sible wave-lengths on the remote chance of ultimately hitting 
on the particular wave-length employed by those whose 
correspondence it was wished to tap. By coding the 
message even this remote chance of surreptitious tapping 
could be rendered useless. 

" This is no mere dream of a visionary philosopher. All 
the requisites needed to bring it within the grasp of daily 
life are well within the possibilities of discovery, and are so 
reasonable and so clearly in the path of researches which 
are now being actively prosecuted in every capital of Europe, 
that we may any day expect to hear that they have emerged 
from the realms of speculation into those of sober fact. 
Even now, indeed, telegraphing without wires is possible 
within a restricted radius of a few hundred yards, and some 
years ago I assisted at experiments where messages were 
transmitted from one part of a house to another without an 
intervening wire by almost the identical means here de- 
scribed." 1 

In 1893 Nikola Tesla, the lightning-juggler, proposed to 

1 The experiments here referred to were made in 1879 by Prof. 
Hughes, who has kindly supplied the author with an account of 
them. As this interesting and important document was received 
too late for embodiment in the text, I must ask my readers to 
refer to Appendix D. 


transmit electrical oscillations to any distance through space, 
by erecting at each end a vertical conductor, connected at 
its lower end to earth and at its upper end to a conducting 
body of large surface. Owing to press of other work this 
experiment was never tried, and so has remained a bare 
suggestion. 1 

At the Eoyal Institution, June 1, 1894, and later in the 
same year at the Oxford meeting of the British Association, 
Prof. Lodge showed how his form of Branly detector could 
be made to indicate signals at a distance of about 150 yards 
from the exciter, but at this time the applicability of his 
experiment to practical long-distance telegraphy was hardly 
grasped by him. Referring to this in his * Work of Hertz ' 
(p. 67, 1897 edition), he says : 

" Signalling was easily carried on from a distance through 
walls and other obstacles, an emitter being outside and a 
galvanometer and detector inside the room. Distance with- 
out obstacle was no difficulty, only free distance is not very 
easy to get in a town, and stupidly enough no attempt was 
made to apply any but the feeblest power so as to test how 
far the disturbance could really be detected. 

"Mr Rutherford, however, with a magnetic detector of 
his own invention, constructed on a totally different prin- 
ciple, and probably much less sensitive than a coherer, did 
make the attempt (June 1896), and succeeded in signalling 
across half a mile full of intervening streets and houses at 

Between 1895 and 1896 Messrs Popoff, Minchin, 
Rutherford, and others applied the Hertzian method to 
the study of atmospheric electricity ; and their mode of 
procedure, in the use of detectors in connection with vertical 
exploring rods, was much the same as that of Marconi. 

1 See a full account of Tesla's marvellous researches in ' Jour. 
Inst. Elec. Engs.' for 1892, No. 97, p. 51. 



Popoff s arrangement especially is so like Marconi's that 
we are tempted to reproduce it from the ' Elektritchestvo ' 
of St Petersburg for July 1896. Fig. 36 shows the 
apparatus, the action of which is easily understood. The 




Fig. 36. 

relay actuates another circuit, not showu, containing a 
Richard's register, which plots graphically the atmospheric 

Prof. PopofFs plans were communicated to the Physico- 
Chemical Society of St Petersburg in April 1895 ; and in a 
further note, dated December 1895, he adds : " I entertain 
the hope that when my apparatus is perfected it will be 
applicable to the transmission of signals to a distance by 
means of rapid electric vibrations when, in fact, a suffi- 
ciently powerful generator of these vibrations is discovered." 
We shall see presently that Popoff was looking in the wrong 
direction. It was not so much a more powerful generator 


(which is easily obtained) that was wanted, as a more 
sensitive detector than the ordinary Branly-Lodge arrange- 
ment which he used. Mr Marconi, we shall see, supplied 
this, and in doing so did the main thing necessary to make 
PopofFs apparatus a practical telegraph. 1 

Mr Preece tells us that in December 1895 Captain 
Jackson, K.N., commenced working in the same direction, 
and succeeded in getting Morse signals through space before 
he heard of Marconi. His experiments, however, were 
treated as confidential at the time, and have not been 

In 1896 the Eev. F. Jervis-Smith had a detector made 
of finely-powdered carbon, such as is used in incandescent 
electric lamps, for observing atmospheric electricity ; and a 
little later (? after Marconi's announcement) he actually 
applied it to telegraphic purposes over a distance of more 
than a mile. This form of detector was to a certain extent 
self-adjusting in that it did not require any tapping 
device. 2 

I now come to Mr Marconi, whose special application of 
Hertzian waves to practical telegraphy will be easily under- 
stood if my readers have carefully followed me in the 
preceding pages. 

His apparatus for short distances, with clear open 
Spaces, consists of the parts which are shown in diagram- 
matic form in figs. 37, 38, 39, and 40. The apparatus at 
the sending station consists of a modified Eighi exciter A 

1 On hearing of Marconi's success in England, Prof. Popoff tried his 
apparatus quasi telegraph (presumably using more sensitive detectors), 
and in April 1897 succeeded in signalling through a space of 1 kilo- 
metre, then through 1, and finally through 5 kilometres, with vertical 
wires, 18 metres high. 

2 Quite recently, October 1898, I have seen it stated that Signer 
Rovelli has found that a detector made of iron filings acts well, and 
requires no tapping. 



(fig. 37), a Euhmkorff coil B, a battery of a few cells c, 
and a Morse key K. 

The exciter consists of two solid brass spheres A B (fig. 38), 
11 centimetres in diameter and 1 millimetre apart, yielding 
with a 6 -inch spark coil 
waves of about 25 centi- 
metres long. The spheres 
are fixed in an oil -tight 
case of parchment or 
ebonite, so that an out- 
side hemisphere of each 
is exposed, the other hemi- 
spheres being immersed 
in vaseline -oil thickened 
by the addition of a little 
vaseline. As already ex- Fig 37 

plained, the use of oil 

has several advantages, all of which combine to increase 
the effect, and therefore the distance at which this effect 

c -o[ ? 

Fig. 38. 

can be detected. It keeps the opposing surfaces of the 
spheres clean and bright ; it gives to the electric waves a 
uniform and regular (periodic) character ; and it reduces 


the length of these waves to the small limits best adapted 
for signalling. 1 Two small balls, also of solid brass, a b, 
are fixed in a line with the large ones, usually about 2 '5 
centimetres apart, and are capable of adjustment. The 
larger the spheres and balls, and the greater the distances 
separating them, the higher the potential of the spark, and 
consequently the greater the distance at which the oscilla- 
tions are perceptible. The balls a b are connected each to 
one end of the secondary coil of the Ruhmkorff apparatus B. 
The primary wire of the induction coil is excited by the 
battery c, thrown in and out of circuit by the key K. The 
efficiency of the sending apparatus depends greatly on the 
power and constancy of the induction coil : thus a coil yield- 
ing a 6-inch spark will be effective up to three or four 
miles ; but for greater distances than this more powerful 
coils, as one emitting 20-inch sparks, must be used. 2 

The various parts of the sending apparatus are generally 
so constructed and adjusted as to emit per second about 250 
million waves of about 1'2 metres long. 

At the receiving station N (fig. 39) is Marconi's special 
form of the Branly-Lodge detector, shown full size in fig. 40. 
This is the part which gave him the most trouble. While 
for laboratory experiments a detector of little delicacy suf- 
ficed to give indications on a sensitive mirror galvanometer 
at a distance of a few yards, Mr Marconi had to seek an 

1 Mr Marconi's later experience has led him to doubt these advan- 
tages, and to discard the use of oil. See 'Jour. Inst. Elec. Engs.,' 
No. 139, p. 311. 

2 But there is a limit ; powerful induction coils of the Ruhmkorff 
kind are difficult to make and keep in order, and do not by reason of 
their residual magnetism admit of the very rapid make-and -break 
action required. Doubtless other and more effective means of excite- 
ment will soon be discovered, as Tesla's oscillators, or by the use of 
Wehnelt's electrolytic contact-breaker, which can be made to inter- 
rupt a current one thousand times and more per second. See 'Jour. 
Inst. Elec. Engs.,' No. 131, p. 317. 



arrangement which would respond sufficiently to the very 
feeble waves which are found at a great distance from the 
source, so as to allow of the passage of a current strong 

A A'_ 

L s 

Fig. 39. 

enough to actuate a telegraph relay. His detector consists 
of a glass tube, 4 centimetres long and 2 '5 millimetres 
interior diameter, into which two silver pole-pieces, 1 milli- 

Fig. 40. 

metre apart, are tightly fitted, so as to prevent any scattering 
of the powder. The small intervening space is filled with a 
mixture of 96 parts of nickel and 4 of silver, not too finely 
powdered, and worked up with a trace of mercury. 

By increasing the proportion of silver powder the sensi- 
tiveness of the detector is increased pro rata; but it is 
better for ordinary work not to have too great sensitiveness, 
as the detector then too readily responds to atmospheric 
electricity and other stray currents. Similarly, the smaller 
the powder space the more sensitive is the instrument ; but 


if too small, the action is capricious. The quantity of 
powder required is, of course, very small, but it must be 
treated with care ; it must neither be too compressed nor 
too loose. If too tight the action is irregular, and often the 
particles will not return to their normal condition, or " deco- 
here," as Lodge expresses it ; if too loose coherence is slight, 
and the instrument is not sufficiently sensitive. The best 
adjustment is obtained when the detector works well under 
the action of the sparks from a small electric trembler at 
one metre's distance. The tube is then hermetically sealed, 
having been previously exhausted of air to about TWo'th 
of an atmosphere. This, though not essential, is desirable, 
as it prevents the oxidation of the powder. 

In its normal condition the metallic powder, as already 
stated, is practically a non-conductor, offering many megohms 
resistance. The particles (to use Mr Preece's expressive 
words) lie higgledy-piggledy, anyhow, in disorder. They 
lightly touch each other in a chaotic manner; but when 
electric waves fall upon them they are polarised order is 
installed they are marshalled in serried ranks and press on 
each other, in a word, they cohere, electrical continuity is 
established, and a current passes, the resistance falling from 
practical insulation to a few ohms or a few hundred ohms 
according to the energy of the received impacts. Usually it 
ranges from 100 to 500 ohms. 

The detector is included in the circuit of two electro- 
magnetic impedance or choking coils n n', a local battery of 
one or two Leclanche cells p, and a fairly sensitive polarised 
relay as ordinarily used in telegraphy R. The impedance or 
choking coils, consisting of a few turns of insulated copper 
wire on a glass tube, containing an iron bar 5 or 6 centi- 
metres long, are intended to prevent the. electric energy 
escaping through the relay circuit. Prof. Silvan us Thomp- 
son doubts the efficacy of this contrivance, but Mr 


Marconi's experience shows its great utility. Thus, when 
the coils are removed, all other things remaining the same, 
the signalling distance is reduced by nearly one-half. 

A A' are resonance plates or wings (copper strips) whose 
dimensions must be adjusted so as to bring the detector 
into tune electrically with the exciter. 

The relay actuates two local circuits on the parallel or 
shunt system, one containing an ordinary Morse instrument 
M, and the other the tapper s. The relay and tapper are 
provided with small shunt coils ^ and s 2 to prevent sparking 
at the contacts, which would otherwise impair the good 
working of the detector. The Morse instrument and the 
tapper may also be connected in series in one circuit, in 
which case the former may be made to act as a buzzer, the 
signals being read by sound. Indeed, the Morse machine 
may be left out altogether and the signals be read from the 
sound of the tapper alone. The printing lever of the Morse 
is so adjusted an easy matter as not to follow the rapid 
makes and breaks of the local current caused by the action 
of the tapper. Consequently, although the current in the 
coils of the Morse is rapidly discontinuous, the lever remains 
down (and prints) so long as the detector is influenced by 
the waves sent out by the exciter. In this way the lever 
gives an exact reproduction of the movements of the distant 
sending key, dots and dashes at the key coming out as dots 
and dashes in the Morse. The speed at which signalling 
can be carried on is but little slower than that in ordinary 
(Morse) telegraphy, fifteen words a minute being easily 

In practice, the sending part of the apparatus should be 
screened as much as possible by interposed metal plates from 
the receiving instruments, so as to prevent local inductive 
interferences ; or better, the detector may be shut up in a 
metal box. 



* This arrangement is effective for short distances, up to 
two miles, with clear open spaces, especially if parabolic 
reflectors are erected behind the exciter and detector, and 
carefully focussed so as to throw the electric rays in the 
right direction. But for long distances, and where obstacles 
intervene, as trees, houses, hills in fact, for practical 
purposes certain modifications are necessary which are 

Fig. 41. 

shown in fig. 41. Reflectors are discarded which are 
troublesome and expensive to make and difficult to adjust. 
One knob of the exciter is connected to a stout insulated 
wire, led to the top of a mast and terminating in a square 
sheet or a cylinder of zinc, or a pennant-like structure of 
wire netting. For still greater distances the wire may 
be flown from a kite or balloon 1 covered with tinfoil. 

1 In a recent popular lecture it is seriously stated that, when kites 
are used to carry the conductors, " the electricity obtained from the 


The other knob of the exciter is connected to a good 

At the receiving station the resonance wings of the 
detector are discarded, and one side is connected to a vertical 
wire and the other side to earth, as in the case of the exciter. 
Of course, in practice only one vertical wire is required at 
each station, as by means of a switch it can be connected 
with the exciter for sending, or with the detector for re- 
ceiving, as may be necessary. The parallelism of the plates 
x and y should be preserved as much as possible in order to 
obtain the best effects. 

The raison cCetre of the earth connections is not yet 
clearly understood. An earth wire on the exciter for lonsj 
distances is essential, but at the detector it may apparently 
be dispensed with without any (appreciable) effect. 1 Break- 
ing the connection does not prove to me that earth does not 
enter into the effect. It only increases the resistance of the 
earth-connecting medium, which now is not wire, but consists 
of the walls, floor, table, and base-board of the instrument. 
Again, why suppose that sparks are emitted at the top of 
the vertical wire only"? Why not also into the ground, 
giving us a complete closed circuit through the ether above 
and through the ground below 1 If I may hazard an opinion 
I would say that the Marconi effect is but, on a large scale, 
an electrical machine effect such as every schoolboy is 

air, when they were flown high enough, was sufficient to enable the 
operator to do away with a primary battery" ! (' Electrical Engineer,' 
October 1, 1897). This is the Mahlon Loomis idea redivivus (see 
p. 73 ante), and is as true as another " vulgar error " to wit, that 
Marconi, and now Tesla, can explode torpedoes and powder-magazines 
at their own sweet will. This, of course, might be done, if they 
could plant a properly adjusted exploding apparatus near the powder ; 
but if they could do this, they could, as Mr Preece says, do many 
other funny things. 

1 Jour. Inst, Elec. Engs., No. 137, pp. 801, 802, 900, 918, 946, 962, 


familiar with, and that it conforms to the same laws and 

However this may be, an earth wire (and a good one too) 
should be used on the detector as well as on the exciter, if 
only as a protection from lightning. The vertical wire is 
practically a lightning - catcher, and the detector is an 
excellent lightning-guard when connected to earth. But if 
disconnected from earth, and lightning strikes the wire, 
then we may expect all the disastrous results which follow 
from a badly constructed or defective lightning-protector. 
The fear, then, that the Marconi apparatus is dangerous 
may be put aside. Being excellent lightning-conductors 
and lightning-guards in one, they may, in my opinion, be 
safely used, even in a powder-magazine. 

Delicate as the apparatus undoubtedly is, and complicated 
as it may seem, its action is simplicity itself to the telegraph- 
ist, differing only in the kind of electricity and the medium 
of communication from that of the everyday telegraph. On 
depressing the key k (fig. 41) to make, say, a dash, induced 
currents are set up in the secondary coil of the Euhmkorff 
machine, which pass in sparks across the spark-gaps 1, 2, and 
3, and out into space at x. The sparks at x set up electric oscil- 
lations in the ether, which are radiated into space in waves. 
On arriving at the receiving station some of these waves 
strike the wire y, are carried to the detector, which coheres, 
allowing the local battery to act ; the relay closes, and the 
Morse instrument sounds, or prints the signal as may be re- 
quired, the tapper all the while doing its work of decohering. 

Marconi's first trials on a small scale were made at 
Bologna, and these proving successful he came to England 
and applied for a patent, June 2, 1896. 1 Soon after, in 

1 This being the first patent of the New Telegraphy order, is his- 
torically interesting. I have therefore thought it convenient to 
reproduce it in Appendix E, with the original rough drawings. 


July, he submitted his plans to the postal-telegraph authori- 
ties, and, to his honour be it said, they were unhesitatingly 
even eagerly taken up by Mr Preece, although, as we 
have already seen, he was introducing a method of his own. 

The first experiments in England were from a room in 
the General Post Office, London, to an impromptu station 
on the roof, over 100 yards distant, with several walls, &c., 
intervening. Then, a little later, trials were made over 
Salisbury Plain for a clear open distance of nearly two miles. 
In these experiments roughly-made copper parabolic reflec- 
tors were employed, with resonance plates on each side of 
the detector (see figs. 37, 39). 

In May 1897 still more extensive trials were made across 
the Bristol Channel between Lavernock and Flat Holm, 3 -3 
miles, and between Lavernock and Brean Down, near 
Weston-super-Mare, 8 '7 miles (see tig. 21, ante). Here the 
reflectors and resonance plates were discarded. Earth and 
vertical air wires were employed, as in fig. 41, the vertical 
wires being in the first case 50 yards high, while in the 
second case kites carrying the wires were had recourse to. 

The receiving apparatus was set up on the cliff at Laver- 
nock Point, which is about 20 yards above sea-level. Here 
was erected a pole, 30 yards high, on the top of which was 
a cylindrical cap of zinc, 2 yards long and 1 yard diameter. 
Connected with this cap was an insulated copper wire 
leading to one side of the detector, the other side of which 
was connected to a wire led down the cliff and dipping into 
the sea. At Flat Holm the sending apparatus was arranged, 
the Ruhmkorff coil used giving 20-inch sparks with an eight- 
cell battery. 

On the 10th May experiments on Mr Preece's electro- 
magnetic method (already fully described) were repeated, 
and with perfect success. 

The next few days were eventful ones in the history of 


Mr Marconi. On the llth and 12th his experiments were 
unsatisfactory worse, they were failures and the fate of 
the new system trembled in the balance. An inspiration 
saved it. On the 13th the receiving apparatus was carried 
down to the beach at the foot of the cliff, and connected by 
another 20 yards of wire to the pole above, thus making a 
height of 50 yards in all. Result, magic ! The instru- 
ments, which for two days failed to record anything intelli- 
gible, now rang out the signals clear and unmistakable, and 
all by the addition of a few yards of wire ! Thus often, as 
Carlyle says, do mighty events turn on a straw. 

Prof. Slaby of Charlottenberg, who assisted at these ex- 
periments, has told us in a few graphic words the feelings 
of those engaged. " It will be for me," he says, " an 
ineffaceable recollection. Five of us stood round the ap- 
paratus in a wooden shed as a shelter from the gale, with 
eyes and ears directed towards the instruments with an 
attention which was almost painful, and waited for the 
hoisting of a flag, which was the signal that all was ready. 
Instantaneously we heard the first tic tac, tic tac, and saw 
the Morse instrument print the signals which came to us 
silently and invisibly from the island rock, whose contour 
was scarcely visible to the naked eye came to us dancing 
on that unknown and mysterious agent the ether!" 

After this the further experiments passed off with scarcely 
a hitch, and on the following day communication was estab- 
lished between Lavernock and Brean Down. 

The next important trials were carried out at Spezia, by 
request of the Italian Government, between July 10 and 18, 
1897. The first three days were taken up with experiments 
between two land stations 3 '6 kilometres apart, which were 
perfectly successful. On the 14th, the sending apparatus 
being at the arsenal of San Bartolomeo, the receiving instru- 
ments were placed on board a tug vessel, moored at various 


distances from the shore. The shore wire was 26 metres 
high, and could be increased to 34 if necessary; the tug wire 
was carried to the top of the mast, and was 16 metres high. 
The results were unsatisfactory : signals came, but they were 
jumbled up with other weird signals, which came from the 
atmosphere (the weather was stormy) in the way which 
telegraph and telephone operators know so well. On the 
15th and 16th (the weather having moderated) better results 
were obtained, and communication was kept up at distances 
up to 7*5 kilometres. 

On the 17th and 18th the receiving apparatus was trans- 
ferred to a warship (ironclad), and, with a shore elevation of 
34 metres and a ship elevation of 22 metres, signals were 
good at all distances up to 12 kilometres, and fairly so at 16 

During these experiments it was observed that whenever 
the funnels, iron masts, and wire ropes of the vessels were 
in line with the shore apparatus the detector did not work 
properly, which was to be expected from the screening pro- 
perty of metals ; but another and more serious difficulty 
was also encountered. When the vessel got behind a point 
of the land which cut off the view of the shore station, the 
signals came capriciously, and good working was not estab- 
lished until the shore was again in full view. Here was a 
difficulty which must be surmounted if the new system was 
to be of any practical utility. We have seen in our account 
of the work of Hertz that electric waves pass without ap- 
preciable hindrance through doors and walls and, generally, 
non-conducting bodies, being only arrested by metals and 
other conductors; but in practice, when we come to deal 
with doors and walls in large masses as trees, buildings, 
hills, especially if near the vertical wires they partake of 
the nature of metals, and largely absorb the waves, just as 
light passes through a thin sheet of glass, but is obscured or 



absorbed by a thick sheet. This difficulty is in the nature 
of things, and must always remain. It is surmountable to 
a very great extent by increasing the height of the vertical 
wires, terminating with suitable capacity areas, and by in- 
creasing the power of the sending and the delicacy of the 
receiving apparatus ; but we speedily reach a limit in these 
directions, so that as far as one can see at present the effec- 
tive distance of the new system must be small compared 
with the older methods. 

Fig. 42, which I borrow from Mr Preece, shows how hills 
are apparently bridged over. 

Fig. 42. 

From a long series of experiments in Italy in 1895 Mr 
Marconi worked out a law of distance which all his later 
experience seems to verify. " The results," he says, " showed 
that the distance at which signals could be obtained varied 
approximately as the square of the height of the capacity 
areas from earth, or, perhaps, as the square of the length of 
the vertical conductors. This law furnishes us with a safe 
means of calculating what length the vertical wire should 
be in order to obtain results at a given distance. The law 
has never failed to give the expected results across dear 
space in any installation I have carried out, although it 
usually seems that the distance actually obtained is slightly 
in excess. I find that, with parity of other conditions, 
vertical wires 20 feet long are sufficient for communicating 


one mile, 40 feet four miles, 80 feet sixteen miles, and 
so on. 

" Professor Ascoli has confirmed this law, and demon- 
strated mathematically, using Neumann's formula, that the 
inductive action is proportional to the square of the length 
of one of the two conductors if the two are vertical and 
of equal length, 1 and in simple inverse proportion of the 
distance between them. Therefore the intensity of the in- 
duced oscillation does not diminish with the increase of 
distance if the length of the vertical conductors is increased 
in proportion, or as the square root of the distance. That 
is, if the height of the wire is doubled, the possible distance 
becomes quadrupled." 2 

On his return to Germany after witnessing the Marconi 
experiments in England, Prof. Slaby in September 1897 
engaged in some very instructive experiments in the vicinity 
of Potsdam, first between Matrosenstation and the church at 
Sacrow, 1*6 kilometre, and then between the former place 
and the castle of Pfaueninsel, 3'1 kilometres. I take the 
following particulars from the ' Electrical Engineer,' De- 
cember 3, 1897 : 

Prof. Slaby recently, at a technical college in Berlin, gave 
an interesting report of his experiments on telegraphy with- 
out wires, or, as he wants it to be called, " spark telegraphy." 
He mentioned an experiment made by himself by which he 
was able to send by means of one wire two different messages 
simultaneously without interfering with each other. He 

1 If of unequal lengths then the action is proportional to the pro- 
duct of the two lengths, which, however, must not be too dissimilar. 

2 This law ia correct for clear open spaces over water ; but over 
land allowance must be made for obstacles, as trees, buildings, hills, 
&c., which carry off some of the passing energy. The conductors 
must be parallel (' Jour. Inst. Elec. Engs.,' No. 137, p. 902), but 
need not necessarily be of the same height, although it is preferable 
that they should be so. 


explained that the continuous current used in ordinary teleg- 
raphy is conducted along the middle of the wire, and he 
proved that electric waves on their way through the ether 
are attracted by wires which come in their way, and that 
they travel along the outside of those wires without in- 
fluencing the interior. In making use of these observations 
he succeeded in sending a wave message along the outside 
of the wire while another message was proceeding through 
the centre by the continuous current. 

Prof. Slaby says that, in conjunction with Dr Dietz, he 
made many experiments with " spark telegraphy " before 
Marconi's inventions became known, but did not achieve 
any important results. 1 

After his return, however, from England he experi- 
mented still further. The Emperor of Germany was present 
at some of these experiments, and put a number of sailors 
and the large royal gardens at Potsdam at his disposal. 
The receiver was erected at the naval station and the 
transmitter on Peacock Island. The first experiments gave 
no result, because the coherers used were a great deal too 
sensitive, and contained, among other things, too much 
silver, and were affected by the electricity in the atmo- 

1 Referring to these experiments in his book, ' Die Funkentele- 
graphie,' Berlin, 1897, Prof. Slaby handsomely acknowledges Marconi's 
merits in the following words : " Like many others, I also had taken 
up this study, but never got beyond the limits of our High School. 
Even with the aid of parabolic reflectors and great capacity of 
apparatus I could not attain any further. Marconi has made a dis- 
covery. He worked with means the full importance of which had not 
been recognised, and which alone explain the secret of his success. I 
ought to have said this at the commencement of my subject, as latterly, 
especially in the English technical press, the novelty of Marconi's 
process was denied. The production of the Hert/ian waves, their 
radiation through space, the sensitiveness of the electric eye, all were 
known. Very good ; but with these means 50 metres were attained, 
but no more." 


sphere, and in consequence were constantly affected even 
when no signals were sent from the sending station. 
Further experiments showed that the result^ increased in 
the same measure as the sensitiveness of the coherer de- 
creased. Prof. Slaby uses now very rough and jagged 
nickel filings which have been carefully cleaned and 
dried. As the receiving station could not be seen from the 
island, the sending station was removed to a church a little 
farther away, and the exciter was put between the columns 
of the portico, while the mast which carried the wire was 
erected on the spire. The experiments then went very well. 

When the sending apparatus was put back a little farther 
into the church, and the wire was put for about a length of 
2 yards parallel with the stone slabs of the floor and a yard 
and a half above it, it ceased to work properly, because the 
waves seek the earth. Hence one must not bring the wire 
too near to the earth, or lay it parallel when near the earth. 
When the sending apparatus was moved back to the island, 
it was found that trees near the wire proved an obstacle 
because they received the waves. Therefore the Professor 
says that it is best to so arrange that the wires on the 
receiver and on the transmitter can be seen from each 
other. Even the sail of a little boat or the smoke from 
a steamer cause small interruptions, which make the words 
more or less indistinct. The waves get through impedi- 
menta, and even through buildings, but there is always 
much loss. In order to make the wire which was placed 
on the island more visible from the mainland, it was 
lengthened from 25 to 65 yards, and placed upon a boat 
on the river. That did not remedy matters ; but when the 
wire on the receiver was also lengthened to 65 yards very 
good results followed, showing that the length of the wire 
is of great importance. 

Prof. Slaby next proceeded, early in October, to experi- 


ment over an open stretch of country, free from all inter- 
vening obstacles, between Eangsdorf (sending station) and 
Schoneberg (receiving station), a distance of 21 kilometres. 
Captive balloons raised to a height of 300 metres were 
employed. On the first two days the results were dis- 
appointing, and the fault was found to be in the vertical 
conductors, which consisted of the wire cables holding the 
balloons. With a double telephone wire there was a slight 
improvement ; and eventually, on the 7th October, " fine 
insulated copper wire of '46 millimetres diameter was sub- 
stituted with excellent results." l 

Correspondence was now always good, except when dis- 
turbed by atmospheric discharges (the weather being- 
stormy). At such times the signals were distorted and con- 
fused, and often the discharges were so strong as to un- 
pleasantly shock the operators, making it necessary to 
handle the apparatus with the greatest care. Here is 
another serious difficulty with which Mr Marconi has to 
contend, and from which we see no escape short of total 
suspension of operations during stormy weather namely, 
the great liability to accident and derangement, not merely 
from lightning flashes, to which all telegraph systems are 
subject, but from all those other electrical disturbances of 
the atmosphere which have hitherto been of little account. 
The greater the distance worked over, the higher must be 
the conductors, and, consequently, the greater must be the 

The apparatus used by Prof. Slaby differed somewhat 
from Marconi's, the following being the more important 
points : 

1. A Weston galvanometer relay, which, it is curious to 

1 The statement in inverted commas needs verification, as theo- 
retically one would suppose the larger wires should have given the 
better result. 


note, is our old friend in modern guise, the Wilkins' 
relay, used by Mr Wilkins in his wireless telegraph 
experiments in 1845 (see p. 38, ante). 

2. An ordinary Branly- Lodge -detector with hard nickel 

powder only. 

3. No impedance or "choking" coils. 1 

The further course of Marconi's experiments is so suc- 
cinctly given by the chairman of the Wireless Telegraph 
Company in a recent address, October 7, 1898, that we 
cannot do better than follow him. 2 

" A year ago," he says, " when this company was started 
(July 1897), Mr Marconi happened to be in Italy making 
experiments for the Italian Government, and for the King 
and Queen at the Quirinal. On his return to this country, 
the first long-distance trial was made between Bath and 
Salisbury. The receiver in this case was given to a post- 
office official, who went to Bath and by himself rigged up a 
station, at which he received signals thirty-four miles distant 
from where they were sent at Salisbury. After this we put 
a permanent station at Alum Bay, Isle of Wight. This 
station at first was used in connection with a small steamer 
that cruised about in the neighbourhood of Bournemouth, 
Boscombe, Poole Bay, and Swanage, a distance of eighteen 
miles from the Needles Hotel station, with which it was in 
constant telegraphic communication. 

" Various exhibitions were given later one at the House 
of Commons, where a station was erected, and another sta- 
tion at St Thomas's Hospital opposite (May 1898). Within 

1 About this time Dr Tuma of Vienna was engaged on similar ex- 
periments, using, however, instead of a Ruhmkorff coil a Tesla oscillator 
or exciter, with nickel powder only in the detector. I have not seen 
any detailed account of these experiments. 

2 I have incorporated a few passages from Mr Marconi's recent paper 
(Institution of Electrical Engineers, March 2, 1899), so as to make the 
account more complete. These are shown in brackets thus [ ]. 


an hour of the time our assistants arrived to put up the 
installation, the system was at work. We had many 
exhibitions at our offices, at which a number of people 
attended; amongst others Mr Brinton, a director of the 
Donald Currie .line of steamers, who asked if we could 
report a ship passing our station. This was done. The 
ship was the Carisbrooke Castle, on her first voyage out, 
and as she passed the Needles a message reporting the 
fact was wirelessly telegraphed to Bournemouth, and there 
put on the ordinary telegraph wires for transmission to 
Mr Brinton. 

"After this Lord Kelvin visited our station at Alum Bay, 
and expressed himself highly pleased with all he saw. He 
sent several telegrams, via Bournemouth, to his friends, for 
each of which he insisted on paying one shilling royalty, 
wishing in this way to show his appreciation of the system 
and to illustrate its fitness for commercial uses. The follow- 
ing day the Italian Ambassador visited the station. Among 
other messages, he sent a long telegram addressed to the 
Aide-de-camp to the King of Italy. As it was in Italian, 
and as Mr Marconi's assistant at Bournemouth had no know- 
ledge of that language, it may be taken as a severe test as, 
in fact, a code message. The telegram was received exactly 
as it was sent. Previously, we had a display for the 
' Electrical Review ' and the ' Times,' both of which papers 
sent representatives. They put the system to every possible 
test, and, among others, sent a long code message, which 
had to be repeated back. In their reports they stated that 
this was done exactly as sent, 

[In May Lloyd's desired to have an illustration of the 
possibility of signalling between Ballycastle and Eathlin 
Island in the north of Ireland. The distance between the 
two positions is seven and a half miles, of which about four 
are overland and the remainder across the sea, a high cliff 


also intervening between the two positions. At Ballycastle 
a pole 70 feet high was used to support the wire, and at 
Eathlin a vertical conductor was supported by the light- 
house 80 feet high. Signalling was found quite possible 
between the two points, but it was thought desirable to 
bring the height of the pole at Ballycastle to 100 feet, as 
the proximity of the lighthouse to the wire at Rathlin 
seemed to diminish the effectiveness of that station. At 
Rathlin we found that the lighthouse-keepers were not long 
in learning how to work the instruments, and after the sad 
accident which happened to poor Mr Glanville, that installa- 
tion was worked by them alone, there being no expert on 
the island at the time. 1 ] 

" Following this, in July last (1898) we were requested 
by a Dublin paper, the 'Daily Express,' to report the 
Kingstown regatta. In order to do this we erected a [land] 
station at Kingstown, and another on board a steamer which 
followed the yachts. A telephone wire connected the 
Kingstown station with the ' Daily Express ' offices, and as 
the messages came from the ship they were telephoned to 
Dublin and published in successive editions of the evening 
papers. 2 

" After this, Mr Marconi was requested to put up a sta- 
tion at Osborne to connect with the Prince of "Wales' yacht 
Osborne. Bulletins of the Prince's health (his Royal High- 
ness, as we all know, met with a lamentable accident just 
before then) were reported to her Majesty : not only that, 
but the royalties made great use of our system during the 
Cowes week. After the regatta had concluded the Prince 

1 Mr Glanville, a promising young electrician (only twenty-five 
years old), was missing from Saturday to the Tuesday evening fol- 
lowing, when his body, terribly mutilated, was found at the foot of 
a cliff 300 feet high in Rathliu Island. 

2 Very full illustrated accounts of this remarkable experiment are 
given in the Dublin ' Mail,' July 20, 21, and 22, 1898. 


wished to cruise about, and he did so as far as Bembridge 
on one occasion. The next day they went over to the 
Needles, at the opposite side of the Isle of Wight. The 
royal yacht was kept in telegraphic communication with the 
Osborne station on the first day. On the second occasion 
they were able not only to communicate with Osborne, but 
also with our station at the Needles Hotel. They rang up 
the Needles Hotel when seven or eight miles away, and 
immediately had a reply, although about the highest land 
in the Isle of Wight lay between the royal yacht and the 
Needles Hotel station. 

" Within the last few days we have had to move our 
station at Bournemouth four' miles farther west, where we 
have put up the same instruments, the same pole, and 
everything at the Haven Hotel, Poole, which is eighteen 
miles from Alum Bay. This increase of distance has no 
detrimental effect on our work ; in fact it seems rather 
easier, if anything, to receive signals at the Haven Hotel 
than at our former station : thus, the height of the conductor 
at Bournemouth was 150 feet, but this is now reduced to 
100 feet, which is a very great improvement. 1 

[The vertical conductors are stranded fa copper wire in- 
sulated with india-rubber and tape. A 10-inch spark induc- 
tion coil is used at each station, worked by a battery of 100 
Obach cells M size, the current taken by the coil being 14 
volts of from 6 to 9 amperes. The sparks take place be- 
tween two small spheres about 1 inch diameter, this form 
of transmitter having been found more simple and more 
effective than the Kighi exciter previously used. The 
length of spark is adjusted to about 1 centimetre, which, 
being much shorter than the coil can give, allows a large 
margin for any irregularity that may occur. No care is 
now taken to polish the spheres at the place where the 
1 The height has since been reduced to 60 feet. 


sparks occur, as working seems better with dull spheres 
than with polished ones.] 

"We have sent our assistants to various countries to 
make demonstrations in connection with our patent rights ; 
and lately we sent one of our staff to Malta, where some 
excellent experiments were carried out for the Government 

" The Marconi invention is the only (electric) telegraph 
by means of which a moving object can be kept in commu- 
nication with any other moving object, or a fixed station, 
and therefore any one can see the great use of the invention, 
not only to the Royal Naval authorities, but also to the 
mercantile marine. A ship fitted with Mr Marconi's 
apparatus can not only keep in telegraphic communi- 
cation with the shore up to any reasonable distance it 
has been thoroughly tested up to twenty -five miles off 
the shore but ships can also, if properly equipped, 
be warned of approaching danger or their proximity 
to dangerous coasts which are fitted with the wireless 
apparatus. 1 

"The weather has no effect at any rate no adverse 

1 I fear the apparatus is not yet adapted for this. Take the case of 
an outlying rock lighthouse. As the electric waves would radiate in 
all directions, a ship in darkness or a fog could not say from the 
intercepted rays what her position was, whether north, south, east, 
or west of the lighthouse, which may be a matter of vital importance 
for her. 

By reverting, however, to the original form of the apparatus (dis- 
carding vertical wires), and by revolving a metallic screen about the 
detector until the position of maximum effect is obtained, the ship 
could possibly fix the direction whence come the rays. But this, 
though important, is not enough. As the ship does not know her 
distance from the rock, it does not tell her enough as to her exact 
position. The distance might possibly be ascertainable if the detector 
could be calibrated to varying degrees of electric energy a very 
great difficulty. 


effect. The only thing we find is that on a foggy day, 
when a place is obscured, everything is made easier for us. 
Our worst electrical day is a fine, bright, sunny day in July, 
when everything can be seen ; but directly everything 
becomes obscured the facilities of wireless telegraphy are 
increased. I had a telegram handed to me just as I came 
in, querying if the Government or the Post Office were not, 
as has been reported, trying to stop us. So far from that 
being the case, they have actually requested us to put the 
system up between Guernsey and Sark, and they have 
offered us a post office at each end for the instruments. 
That matter is occupying our attention, and we shall go on 
with it at once. Also, as we wish to work the thing in 
France as well as in England, we now intend to put up a 
station between Calais and Dover. There is not the least 
doubt of success being achieved, because we are doing a 
parallel distance to-day without the slightest difficulty. The 
sea between Calais and Dover is the same sea as between 
the Isle of Wight and Poole, so the things being equal in 
both cases we may expect the same success between Calais 
and Dover as between the other points." 

[In December of last year the Company thought it desir- 
able to demonstrate that the system was available for tele- 
graphic communication between lightships and the shore. 
This, as you are aware, is a matter of much importance, as 
all other systems tried so far have failed, and the cables by 
which ships are connected are exceedingly expensive, and 
require special moorings and fittings, which are troublesome 
to maintain and liable to break in storms. The officials of 
Trinity House offered us the opportunity of demonstrating 
to them the utility of the system between the South Fore- 
land Lighthouse and one of the following light-vessels 
viz., the Gull, the South Goodwin, and the East Goodwin. 
We naturally chose the one farthest away the East Good- 


win which is just twelve miles from the South Foreland 

[The apparatus was taken on board in an open boat and 
rigged up in one afternoon. The installation started working 
from the very first, December 24, without the slightest 
difficulty. The system has continued to work admirably 
through all the storms, which during this year have been 
remarkable for their continuance and severity. On one 
occasion, during a big gale in January last, a very heavy sea 
struck the ship, carrying part of her bulwarks away. The 
report of this mishap was promptly telegraphed to the 
superintendent of Trinity House, with all details of the 
damage sustained. 

[The height of the wire on board the ship is 80 feet, the 
mast being for 60 feet of its length of iron, and the re- 
mainder of wood. The aerial wire is led down among a 
great number of metal stays and chains, which do not 
appear to have any detrimental effect on the strength of the 
signals. The instruments are placed in the aft-cabin, and 
the aerial wire comes through the framework of a skylight, 
from which it is insulated by means of a rubber pipe. As 
usual, a 10-inch coil is used, worked by a battery of dry 
cells, the current taken being about 6 to 8 amperes at 14 

[Various members of the crew learned in two days how to 
send and receive, and in fact how to run the station ; and 
owing to the assistant on board not being as good a sailor 
as the instruments have proved to be, nearly all the messages 
during very bad weather are sent and received by these 
men, who, previous to our visit to the ship, had probably 
never heard of wireless telegraphy, and were certainly 
unacquainted with even the rudiments of electricity. It is 
remarkable that wireless telegraphy, which had been con- 
sidered by some as rather uncertain, or that might work one 



day and not the next, has proved in this case to be more 
reliable, even under such unfavourable conditions, than the 
ordinary land wires, very many of which were broken down 
in the storms of last month. 1 

[The instruments at the South Foreland Lighthouse are 
similar to those used on the ship ; but as we contemplate 
making some long-distance tests from the South Foreland 
to the coast of France, the height of the pole is much 
greater than would be necessary for the lightship installa- 
tion alone. 2 ] 

It has been objected to the Marconi system that, with 
the removal of the reflectors and the resonance wings on 
the detectors, the condition of privacy in telegrams no 
longer holds good, since any one provided with the neces- 
sary apparatus can receive the signals at any point within 
the circle of which the sending station is the centre and the 
receiving station the radius. Another, and in some cases 
more serious, objection is that any one by erecting a wire or 
wires in the vicinity of a Marconi station can propagate 
therefrom Hertzian waves, which by interference will so 
confuse the effects as to make correct signalling impractic- 
able. It is not even necessary to propagate counter-waves : 
a large sheet of metal (or several such sheets) erected high 
in air, in line with the stations, and connected by a wire to 
the earth, will intercept much of the energy, and the more 
so as it is near to either of the stations, and at right angles 
to the direction of the waves. Thus, if used for naval or 
military purposes, an enemy could either tap the dispatches 
or render them unintelligible at pleasure. The latter ob- 
jection is from the nature of things unavoidable, and in 

1 Pace Mr Marconi, the system is affected by stormy weather. See 
p. 218 ante; also 'Jour. Inst. Elec. Engs.,' No. 137, p. 945. 

2 This has since been done. See all the London papers of March 29 
and 30, 1899. 


practice must limit the application of the system to lines of 
communication sufficiently apart as not to interfere with one 
another. The first objection, however, can be obviated by 
reverting to the condition of syntony or resonance, and 
it is in this direction that improvements may soon be 
expected. 1 

Dr Oliver Lodge, F.R.S., the distinguished Professor of 
Physics, University College, Liverpool, and the great dis- 
ciple and expounder of Hertz in England, has long been 
engaged on this problem of a Hertzian-wave telegraph 
more especially with a view of securing syntony in the 
sending and receiving apparatus, and thereby limiting the 
communications to similarly attuned instruments, the ab- 
sence of which selective character is at present one of the 
great drawbacks of the Marconi system. 

We have seen (p. 200, ante) that as early as June 1, 1894, 
Prof. Lodge had exhibited apparatus which was effective 
for signalling on a small scale, but, as he says, "stupidly 
enough no attempt was then made to apply any but the 
feeblest power, so as to test how far the disturbance could 
really be detected. . . . There remained, no doubt, a 
number of points of detail, and considerable improvements 
in construction, if the method was ever to become practic- 
ally useful." ' These he has since worked out, and some of 

1 Indeed we already hear of radical changes. Mr Pasqualini, who 
is charged with the working of the Marconi system under the Italian 
Government, is reported to have found that electrical oscillations do 
not entirely explain the process, and, following out his idea, has 
altered the apparatus greatly. He is able to signal with certainty 
over a distance of twenty-four miles " with apparatus that requires 
no attention, and is not erratic like Marconi's " (' Electrical Engineer,' 
April 7, 1899). Then, news comes from Vienna that Mr Bela Schafer, 
a student of the Buda-Pesth Polytechnic, has so altered the Marconi 
apparatus that he is able to determine the presence and course of 
a ship six to eight miles distant. 

2 The Work of Hertz, pp. 67, 68. 



them are embodied in his patent, No. 11,575, of May 10, 
1897, " Improvements in Syntonised Telegraphy without 
Line Wires." 

As capacity areas, spheres or square plates of metal may 
be employed ; but for the purpose of combining low resist- 
ance with large electro-static capacity, cones or triangles are 
preferred, with the vertices adjoining and their larger areas 
spreading out into space. Or a single insulated surface may 

H H 

Fig. 43. 

be used in conjunction with the earth the earth, or con- 
ductors embedded in it, constituting the other capacity area. 
As radiation from these surfaces is greater in the equatorial 
than in the axial direction, so, when signalling in all direc- 
tions is desired, the axis of the emitter should be vertical. 
Moreover, radiation in a horizontal plane is less likely to 
be absorbed during its passage over partially conducting 
earth or water. 

Fig. 43 shows the arrangement for long-distance signalling. 


H H 1 are large triangular sheets of metal, which by means 
of suitable switches (not shown) can be connected to the 
sending- or the receiving apparatus as desired. Those on 
the left-hand side of the figure are shown in connection 
with polished knobs H 2 H 3 (protected by glass from ultra- 
violet light), which form the adjustable spark-gap of the 
exciter. Between each capacity area and its knob is 
inserted a self -inductance coil of thick wire or metallic 
ribbon (see H 4 , fig. 44) suitably insulated, the object of 
which is to prolong the electrical oscillations in a succession 
of waves-, and thereby obtain a definite frequency or pitch, 
rendering syntony possible, since exactitude of response 
depends on the fact that with the emission of a number of 
successive waves the feeble impulse at the receiving station 
is gradually strengthened till it causes a perceptible effect, 
on the well-known principle of sympathetic resonance. 

The capacity areas and inductance coils are exactly alike 
at the two communicating stations, so as to have the same 
frequency of electrical vibration. This frequency can be 
altered either by varying the capacity of the Leyden jars 
used in the exciting circuit, or by varying the number and 
position of the inductance coils, or by varying both in the 
proper degree, thus permitting only those stations whose 
rate of oscillation is the same to correspond. 

To actuate the exciter a Kuhmkorff coil may be used, or 
a Tesla coil, a Wimshurst machine, or any other high 
tension apparatus. 

Fig. 44 shows the details of the arrangement for exciting 
and detecting the electric waves. When used as a trans- 
mitter the receiving circuit is disconnected from the capacity 
areas by a suitable switch (not shown). Let us first con- 
sider the arrangement as a transmitter. Putting the Euhm- 
korff coil A in action, it charges the Leyden jars J J, whose 
outer coatings are connected, first, through a self -inductance 



coil H 5 of fairly thin wire, so as to permit of thorough 
charging of the jars ; and, second, to the " supply gaps " 
H 6 H 7 . When the jars are fully charged to sparking- point, 
sparks occur at the " starting-gap " H 8 . These precipitate 
sparks at the " supply gaps," which evoke electrical charges 
in the capacity areas H H 1 . These charges surge through 
the inductance coils H 4 , and spark into each other across 
the " discharge gap " between the knobs H 2 H 3 . This last 

Fig. 44. 

discharge, according to Prof. Lodge, is the chief agent in 
starting the oscillations which are the cause of the emitted 
waves ; but it is permissible to close the " discharge gap," 
and so leave the oscillations to be started by the sparks at 
the " supply gaps " only, whose knobs must then be polished 
and protected from ultra-violet light, " so as to supply the 
electric charge in as sudden a manner as possible." 

When used as a receiver the " discharge-gap " is bridged 
over by a suitable cut-out, and connection is made with the 



receiving circuit, as shown on the top of fig. 44. As 
detector, Lodge uses 

1. His own original form of coherer, fig. 45, wherein 
a metallic point N rests lightly on a flat metallic surface 
o (for instance, a needle point of steel or platinum making 
light contact with a steel or aluminium bar like a watch 
spring), fixed at one end p, and delicately adjustable by a 
micrometer screw Q, so as to regulate the pressure at the 
point N. Or 

2. A Branly tube filled with selected iron filings of 


Fig. 45. 

uniform size, sealed up in a good vacuum, and with the 
electrodes, which are of platinum, reduced to points a short 
distance apart. 

His latest form of the Branly coherer is shown full size in 
fig. 46, and is said to be exceedingly sensitive and certain 
in its action, especially in a very high vacuum. A A is a 
glass tube held tightly by ebonite supports B B ; c is a 
pocket or reservoir for spare filings, which can be added to, 
or taken from, the effective portion as required by inverting 
the tube ; D D are the silver electrodes immersed in the 
filings, which are, as before, of carefully selected iron of 



uniform size as nearly as possible ; E is one of the terminals 
of the silver electrodes, the other of which is hidden from 

The instrument is secured by the clamp screw F to any 

convenient support, to 
which the tapping or 
decohering apparatus is 
applied. 1 

When an electric wave 
from a distant exciter 
arrives and stimulates 
electric vibrations in the 
syntonised capacity areas, 
the electrical resistance 
of the coherer suddenly 
and greatly falls and per- 
mits the small battery F, 
fig. 44, to actuate a relay 
G, or a telephone, or other 
telegraphic instrument. 

To break contact, or to 
restore the original great 
resistance of the coherer, 
any form of mechanical 
vibration suffices, as a 
clock, or a tuning-fork, 
or a cog-wheel (as in fig. 
45), or other device for 
causing a shake or 


Fig. 46. 
by a spring, 

tremor, and kept in 
or weight, or by electrical means. 

1 It appears that to Professor Blondel is due the credit of first 
constructing a coherer of this kind in August 1898. See the ' Elec- 
trician,' vol. xliii. p. 277. 


Indeed, the mere motion of any clockwork attached to 
the coherer stand will suffice, an exceedingly slight, 
almost imperceptible, tremor being all that is usually 

Usually the coherer is arranged in simple series with 
the battery and telegraphic instrument, and is so joined to 
the capacity areas as to include in its circuit the self -induct- 
ance coils an arrangement which Prof. Lodge considers of 
great advantage, or, as he says, "an improvement on any 
mode of connection that had previously been possible with- 
out these coils." 

The patent specification figures and describes another 
way viz., enclosing the inductance coils in an outer or 
secondary coil (constituting a species of transformer), and 
making this coil part of the coherer circuit. In this case 
the coherer is stimulated by the waves in the secondary coil 
rather than primarily by those in the inductance coils, which 
with their capacity areas are thus left free to vibrate without 
disturbance from attached wires. 

In all cases it is permissible, and sometimes desirable, to 
shunt the coils of the telegraphic instrument G by means of 
a fine wire or other non-inductive resistance coil w, "in 
order to connect the coherer more effectively and closely to 
the capacity areas." 

At the Royal Society Conversazione on May 11, 1898, a 
complete set of Lodge's apparatus was shown in action, in 
which certain modifications in the signalling and recording 
parts were introduced at the suggestion of Dr Alexander 
Muirhead. Instead of the ordinary Morse key, Muirhead's 
well-known automatic transmitter with punched tape was 
employed at one end of the suite of rooms, and a siphon- 
recorder as the receiving instrument at the other end. The 
recorder was so arranged as to print, not as usually zigzag 
traces, but (the needle working between stops) a momentary 


deflection mark for a dot and a longer continued mark for 
a dash. 

The siphon-recorder is so quick in its responses that it 
indicates each one of the torrent of sparks emitted from the 
sending apparatus : hence a dash is not merely a deflection 
held over, but is made up of a series of minute vibrations ; 
and even a dot is seen to consist of similar vibrations, 
though of course of a lesser number. If the speed of 
signalling is slow and the recorder tape moves slowly, these 
vibrations appear as actual dots and dashes ; but each signal, 
when examined with a microscope, is seen to consist of a 
short or long series of lines representing the constituent 

At a slow rate of working the signals can thus be got 
with exceeding clearness ; but for actual signalling this is 
not at all necessary, and it is possible to attain a high speed, 
making such brief contacts that a single deflection of the 
recorder needle indicates a dot, and three consecutive deflec- 
tions a dash. The paper thus marked does not look like 
the ordinary record, but more resembles the original Morse 
characters as depicted on pp. 404 and 409 of Shaffner's 
' Telegraph Manual ' (New York, 1859), and is easily legible 
with a little practice. 

An ordinary telephone was also available as a receiver, 
connected through a transformer coil, in which the dots and 
dashes were heard very clearly and distinctly. 

The apparatus is reported to have worked well (except at 
the high speeds, when it occasionally missed fire), and did 
not seem to be in the least affected by any of the numerous 
electrical exhibits in the neighbourhood, although some of 
them must have set up considerable radiation of Hertzian 

Based on the same principles viz., the emission of 
electric waves at one place and their detection by some 


form of coherer at another place there is naturally a 
similarity in the outlines of the Lodge system and that of 
Marconi for short distances (where vertical wires are not 
used), as depicted in fig. 39, ante. The differences are 
differences of arrangement and detail only, but they appear 
to be fraught with some important consequences. 

In the first place, Prof. Lodge claims that his arrange- 
ment of the sending apparatus is a more persistent exciter, 
in that it emits a longer train of longer waves, 1 which by 
acting cumulatively on the detector breaks down its insula- 
tion, when more powerful but fewer impulses of shorter 
waves might be inoperative. Then in the next place, this 
element of persistency permits of the use of syntonising 
contrivances, by means of which the rate of oscillation of 
any desired set of instruments can be accurately attuned so 
that only those instruments can correspond, without affect- 
ing or being affected by other sets tuned to a different fre- 
quency, thus securing the undoubted advantage of privacy 
in the communications. 

Lodge's arrangement has worked well in the laboratory 
and lecture-room, but he does not appear to have tried it 
(which is a pity) over any considerable distance, so that it 
remains to be seen how far he can go without having 
recourse to vertical wires, which Marconi finds so essential 
for practical work over distances of more than two or three 
miles. 2 

A few words as to the future, by way of conclusion, and 
our task is completed. On this point we find some recent 
remarks of Prof. Silvanus Thompson so appropriate that we 
quote them in full, as being more authoritative than anything 

1 For some important observations on this point see Mr A. Camp- 
bell Swinton, 'Jour. Inst. Elec. Engs.,' No. 139, p. 317. 

2 For Professor Lodge's newest developments see his paper, ' Jour. 
Inst. Elec. Engs.,' No. 137, p. 799, which deserves careful study. 


we could ourselves say. Prof. Thompson has thoroughly 
studied the subject, and therefore " speaks by the card." 

"It has been shown," he says, "that there are three 
general methods of transmitting electric signals across space. 
All of them require base lines or base areas. The first 
conduction requires moist earth or water as a medium, and 
is for distances under three miles the most effective of the 
three. The second induction is not dependent upon 
earth or water, but will equally well cross air or dry rock. 
The third electric wave propagation requires no medium 
beyond that of the ether of space, but is interfered with by 
interposed things such as masts or trees. Given proper base 
lines or base areas, given adequate methods of thro wing- 
electric energy into the transmitting system, and sufficiently 
sensitive instruments to pick up and translate the signals, it 
is possible, in my opinion, so to develop each of the three 
methods that by any one of them it will be possible to 
establish electric communication between England and 
America across the intervening space. It is certainly pos- 
sible, either by conduction or by induction; whether by 
waves I am somewhat less certain. Conduction might very 
seriously interfere with other electric agencies, since the 
waste currents in the neighbourhood of the primary base 
line would be very great. It is certainly possible either by 
conduction or induction to establish direct communication 
across space with either the Cape, or India, or Australia 
(under the same assumptions as before), and at a far less cost 
than that of a connecting submarine cable. 

" Instruments which operate by means of alternating cur- 
rents of high frequency, like Mr Langdon-Davies's phono- 
phore, are peculiarly liable to set up disturbance in other 
circuits. A single phonophore circuit can be heard in lines 
a hundred miles away. When this first came to my notice 
it impressed me greatly, and coupled in my mind with the 


Ferranti incident mentioned above" (see note, p. 145, ante), 
"caused me to offer to one of my financial friends in the City, 
some eight years ago, to undertake seriously to establish 
telegraphic communication with the Cape, provided .10,000 
were forthcoming to establish the necessary basal circuits in 
the two countries, and the instruments for creating the cur- 
rents. My offer was deemed too visionary for acceptance. 
The thing, however, is quite feasible. The one necessary 
thing is the adequate base line or area. All the rest is 
detail." l 

En attendant, we have the Marconi system, which has been 
proved to be practicable up to thirty-five miles, and within 
this limit there ought to be a wide and useful field for 
activity. Thus, many outlying islands are within this dis- 
tance from each other and from the continents, with which 
communication at all times has hitherto been practicable 
only by the use of cables, which are always costly to make 
and lay, and often costly to keep in repair. Here, especially 
between places where the traffic is not great, is a large field 
to be occupied as cables grow old and fail. 

Then we have just seen from the address of the chairman 
of the Wireless Telegraph Company that negotiations are 
going on with Lloyd's which, if carried into practical effect, 
will result in an extensive application for signalling between 
Lloyd's stations and outward and inward bound vessels 
passing in their vicinity. Indeed it is not rash to predict 
that the lighthouses and lightships around the coasts, not 
only of the British Isles but of all countries, will in time 
be supplied with wireless telegraphs, keeping up constant 
correspondence with all who go down to the sea in ships. 
Then, again, there is the application to intercommunication 
between ships at sea. Ships carrying the Marconi ap- 
paratus can carry on a definite conversation with the occu- 
1 Journal, Society of Arts, April 1, 1898. 


pants of lighthouses and lightships and with each other. 
It will readily be seen that this might, in many cases, be 
far more serviceable than the few light signals now obtain- 
able, or the signalling by flags a tedious process at best, 
and one that is often full of uncertainty, if not of positive 

Turning from sea to land, we find, for the reasons we 
have already indicated, a more circumscribed field of ap- 
plicationat all events until means are devised for focus- 
sing the electric rays and rendering the apparatus syntonic. 
But even then, although by these means we will be able to 
record messages only where intended, there still remain 
cross interferences of which I fear we can never be rid, 
and therefore we can never use the system in a network 
of lines as now, where wires cross, recross, and overlap each 
other in all ways and directions. The waves of electricity, 
like waves of light and sound in similar circumstances, 
would so interfere with each other that the result would be 
chaos. Therefore wireless telegraphy can only be used 
in lines removed from each other's disturbing influences, 
as in sparsely populated countries and undeveloped regions. 

However, many cases of impromptu means of communi- 
cation arise where, as Prof. Lodge says, it might be advan- 
tageous to "shout" the message, spreading it broadcast 
to receivers in all directions, and for which the wireless 
system is well adapted, seeing that it is so inexpensive and 
so easily and rapidly installed, such as for army manoeu- 
vres, for reporting races and other sporting events, and, 
generally, for all important matters occurring beyond the 
range of the permanent lines. 

But for the regular daily correspondence of a nation 
with its lines ramifying in all directions and carrying 
enormous traffics, the Marconi system is not adapted, 
no more than any other wireless method that has been 


proposed, or is likely to be invented. So, for a long time to 
come we must keep to our present telegraphic and tele- 
phonic wires, using the wireless telegraph as an adjunct for 
special cases and contingencies such as I have mentioned. 


April 17, 1899. 

On the 27th of last month communication was established 
by the Marconi system between England and France. As 
all the London daily papers of March 29 and 30 contain full 
and glowing accounts of this installation, it may not be 
necessary to do more than to refer my readers to these 
reports. Still I think it desirable, so as to bring my record 
quite up to date, to add these few words as the book is 
passing through the press. 

" On this side of the Channel the operations took place, by 
permission of the Trinity House, in a little room in the front 
part of the engine-house from which the power is derived for 
the South Foreland lighthouses. The house is on the top 
of the cliffs overlooking the Channel. The demonstrations 
are being conducted for the benefit of the French Govern- 
ment, who have the system under observation, and besides 
Signer Marconi there were present at the Foreland yesterday 
Colonel Comte du Bontavice de Heussey, French Military 
Attache in England ; Captain Ferrie, representing the 
French Government; and Captain Fieron, French IsTaval 
Attache in England. During the afternoon a great number 
of messages in French and English crossed and recrossed 
between the little room at the South Foreland and the Chalet 
D'Artois, at Wimreux, near Boulogne. 

"The whole of the apparatus stood upon a small table about 
3 feet square, in the centre of the room. Underneath the 
table the space was fitted with about fifty primary cells ; a 


10 -inch induction coil occupied the centre of the table. 
The spark is 1J centimetre long, or about three-quarters of 
an inch ; the pole off the top of which the current went into 
space is 150 feet high. The length of spark and power of 
current were the same as used for communication with the 
East Goodwin lightship, a fact which seems remarkable 
when it is considered that the distance over which the 
messages were sent yesterday was nearly three times as 
great. The greater distance is compensated for by the 
increased height of the pole. 

" Throughout the whole of the messages sent yesterday 
there was not once a fault to be detected everything was 
clearly and easily recorded. The rate of transmission was 
about fifteen words a minute." 1 

The first international press message sent by the new 
system was secured by the 'Times,' and is as follows : 

" (From our Boulogne Correspondent) 

"WIMKEUX, March 28. 

"Communication between England and the Continent 
was set up yesterday morning by the Marconi system of 
wireless telegraphy. The points between which the experi- 
ments are being conducted are South Foreland and 
Wimreux, a village on the French coast two miles north of 
Boulogne, where a vertical standard wire, 150 feet high, has 
been set up. The distance is thirty-two miles. The experi- 
ments are being carried on in the Morse code. Signor 
Marconi is here conducting the trials, and is very well 
satisfied with the results obtained. 

"This message has been transmitted by the Marconi 
system from Wimreux to the Foreland." 

Other demonstrations (for Mr Marconi will no longer 

1 The Daily Graphic, March 30, 1899. 


permit us to call them "experiments" and rightly) are 
now contemplated, as between Newhaven and Dieppe, 
sixty-four miles ; between Nice and Cape Corso in Corsica, 
over a hundred miles ; between the South Foreland and 
the Eiffel Tower, about 230 miles; and, finally, between 
England and America, which, as shown in the First Period 
of this history, was the dream of the earliest experimenters 
in wireless telegraphy. 

A press telegram of April 12 says: "The Wireless 
Telegraph Company have been approached by the repre- 
sentative of a proposed syndicate which desires to acquire 
the sole rights of establishing wireless telegraphic communi- 
cation between England and America. The directors of 
the Company will consider the matter at their first meeting, 
which is fixed for an early date." 

Thus I end my task as I began it, with a dream the 
self-same dream ! As to its realisation in the distant future 
who can say nay ? 

" There are more things in heaven and earth, Horatio, 
Than are dreamt of in our philosophy." 

In conclusion, I give a few extracts from a letter (the 
'Times,' April 3, 1899) of Prof. Fleming of the University 
College, London. Prof. Fleming is an expert in electrical 
science, and therefore his views may be taken as represent- 
ing the last word on our subject : 

To the Editor of the ' Times.' 

" SIR, During the last few days I have been permitted 
to make a close examination of the apparatus and methods 
being employed by Signer Marconi in his remarkable tele- 
graphic experiments between South Foreland and Boulogne, 
and at the South Foreland lighthouse have been allowed by 



the inventor to make experiments and transmit messages 
from the station there established both to France and to the 
lightship on the Goodwin Sands, which is equipped for 
sending and receiving ether wave signals. Throughout the 
period of my visit messages, signals, congratulations, and 
jokes were freely exchanged between the operators sitting on 
either side of the Channel, and automatically printed down 
in telegraphic code signals on the ordinary paper slip at the 
rate of twelve to eighteen words a minute. Not once was 
there the slightest difficulty or delay in obtaining an instant 
reply to a signal sent. No familiarity with the subject 
removes the feeling of vague wonder with which one sees a 
telegraphic instrument merely connected with a length of 
150 feet of copper wire run up the side of a flagstaff begin 
to draw its message out of space and print down in dot 
and dash on the paper tape the intelligence ferried across 
thirty miles of water by the mysterious ether. . . . v 

"I cannot help thinking that the time has arrived for a 
little more generous appreciation by his scientific contem- 
poraries of the fact that Signer Marconi has by minute atten- 
tion to detail, and by the important addition of the long, 
vertical air wire, translated one method of space telegraphy 
out of the region of uncertain delicate laboratory experiments 
and placed it on the same footing as regards certainty of 
action and ease of manipulation, so far as the present results 
show, as any of the other methods of electric communica- 
tion employing a continuous wire between the two places. 
This is no small achievement. The apparatus, moreover, is 
ridiculously simple and not costly. With the exception of 
the flagstaff and 150 feet of vertical wire at each end, he can 
place on a small kitchen table the appliances, costing not 
more than .100 in all, for communicating across thirty or 
even a hundred miles of channel. . . . 

" In the presence of the enormous practical importance 


of this feat alone, and of the certainty with which com- 
munication can now be established between ship and shore 
without costly cable or wire, the scientific criticisms which 
have been launched by other inventors against Signor 
Marconi's methods have failed altogether in their appreci- 
ation of the practical significance of the results he has 
brought about. 

" The public, however, are not in the least interested in 
learning the exact meed of merit to be apportioned to various 
investigators in the upbuilding of this result. They do, 
however, want to know whether the new method of com- 
munication across the Channel established by the expendi- 
ture of a few hundred pounds will take the place to any 
considerable extent of submarine cables which have cost 
many thousands of pounds to lay and equip. They do also 
desire to learn what reasons, if any, will prevent every 
lighthouse and lightship round our coasts from being forth- 
with furnished with the necessary apparatus for placing it 
in instantaneous and secure connection with the mainland. 
They also hope to hear that the methods can be applied to 
enable ships to be able in addition to communicate instantly, 
in case of need, with shore stations. To understand how far 
these things can be done, and to appreciate the necessary or 
present limitations of the method, it is requisite to explain 
that each vertical wire or rod connected to a Marconi receiv- 
ing or sending apparatus has a certain ' sphere of influence/ 
Signor Marconi has proved by experiment up to certain 
limits that the distance to which effective signalling extends 
varies as the square of the height of the rod. A wire 20 
feet high carries the effective signal one mile, 40 feet high 
four miles, 80 feet sixteen miles, and so on. Up to the 
present time he has not yet discovered any method of 
shielding any particular rod so as to render it responsive 
only to signals coming from one station, and not from all 


others within its sphere of influence. In spite, however, of 
what has been said, there is no inherent impossibility in 
attaining this desired result. At present all signals sent 
from the South Foreland to France affect the receiver on 
board the Goodwin lightship. But this offers no difficulty. 
In an ordinary electric bell system in a hotel the servant 
recognises the room from which the signal conies by means 
of a simple apparatus called an indicator, and a very similar 
arrangement can be applied to distinguish the origin of an 
ether wave signal when several instruments are at work in a 
common region. Subsequent inventions, as also, perhaps, 
the promulgation of some necessary Board of Trade regula- 
tions for the use of the ether, will prevent official ether 
wave receivers from being disturbed by vagrant electric 
waves sent out by unauthorised persons in their neighbour- 
hood. The practical upshot, however, of the matter is that 
at present if more than two stations are not established 
within certain regions, these stations, pair and pair, can 
communicate with each other freely and regularly by means 
of ether wave signals sent out and received by long vertical 
rods or wires. No state of the atmosphere, and neither 
darkness nor storm, interrupts, so far as yet found, the 
freedom of communication. 

" Up to the present time none of the other systems of 
wireless telegraphy employing electric or magnetic agencies 
has been able to accomplish the same results over equal 
distances. Without denying that much remains yet to be 
attained, or that the same may be affected in other ways, 
it is impossible for any one to witness the South Foreland 
and Boulogne experiments without coming to the conclusion 
that neither captious criticism nor official lethargy should 
stand in the way of additional opportunities being afforded 
for a further extension of practical experiments. Wireless 
telegraphy will not take the place of telegraphy with wires 


each has a special field of operations of its own. But the 
public have a right to ask that the fullest advantage shall 
be taken of that particular sendee which ether wave teleg- 
raphy can now render in promoting the greater safety of 
those at sea ; and that, in view of our enormous maritime 
interests, this country shall not permit itself to be outraced 
by others in the peaceful contest to apply the outcome of 
scientific investigations and discoveries in every possible 
direction to the service of those who are obliged to face the 
perils of the sea. If scientific research has forged a fresh 
weapon with which in turn to fight Nature, ' red in tooth 
and claw,' all other questions fade into insignificance in 
comparison with the inquiry how we can take the utmost 
advantage of this addition to our resources. I am, &c., 





Before Hertz. 

SUBSTANCE of a lecture by Prof. Oliver Lodge, London In- 
stitution, December 16, 1880. 1 

Ever since the subject on which I have to speak to-night 
was arranged, I have been astonished at my own audacity 
in proposing to deal, in the course of sixty minutes, with 
a subject so gigantic and so profound that a course of sixty 
lectures would be inadequate for its thorough and exhaustive 
treatment. I must, therefore, confine myself to some few of 
the most salient points in the relation between electricity and 
light, and I must economise time by plunging at once into the 
middle of the matter without further preliminary. 

What is electricity ? We do not know. We cannot assert 
that it is a form of matter ; neither can we deny it. On the 
other hand, we cannot certainly assert that it is a form of 
energy ; and I should be disposed to deny it. It may be 
that electricity is an entity per se, just as matter is an 
entity per se. Nevertheless, I can tell you what I mean 
by electricity by appealing to its known behaviour. 

Here is a voltaic battery. I want you to regard it, and 
all electrical machines and batteries, as kinds of electricity- 
pumps, which drive the electricity along through the wire 
very much as a water-pump can drive water along pipes. 

1 Based on a report in ' Design and Work,' February 5, 1881. 


While this is going on, the wire manifests a whole series of 
properties, which are called the properties of the current. 

[Here were shown an ignited platinum wire, the electric 
arc between two carbons, an electric machine spark, an in- 
duction coil spark, and a vacuum tube glow. Also a large 
nail was magnetised by being wrapped in the current, and 
two helices were suspended and seen to direct and attract 
each other.] 

To make a magnet, then, we only need a current of elec- 
tricity flowing round and round in a whirl. A vortex or 
whirlpool of electricity is in fact a magnet, and vice versd. 
And these whirls have the power of directing and attracting 
other previously existing whirls according to certain laws, 
called the laws of magnetism. And, moreover, they have 
the power of exciting fresh whirls in neighbouring con- 
ductors, and of repelling them according to the laws of 
diamagnetism. The theory of the actions is known, though 
the nature of the whirls, as of the simple streams of elec- 
tricity, is at present unknown. 

[Here was shown a large electro-magnet and an induction- 
coil vacuum discharge spinning round and round when placed 
in its field.] 

So much for what happens when electricity is made to 
travel along conductors i.e., when it travels along like a 
stream of water in a pipe, or spins round and round like 
a whirlpool. 

But there is another set of phenomena, usually regarded 
as distinct and of another order, but which are not so 
distinct as they appear, which manifest themselves when 
you join the pump to a piece of glass or any non-conductor 
and try to force the electricity through that. You succeed 
in driving some through, but the flow is no longer like that 
of water in an open pipe ; it is as if the pipe were com- 
pletely obstructed by a number of elastic partitions or dia- 
phragms. The water cannot move without straining and 
bending these diaphragms, and if you allow it, these strained 
partitions will recover themselves and drive the water back 
again. [Here was explained the process of charging a Leyden 
jar.] The essential thing to remember is that we may have 
electrical energy in two forms, the static and the kinetic; 


and it is therefore also possible to have the rapid alternation 
from one of these forms to the other, called vibration. 

Now we will pass to the second question : What do you 
mean by light ? And the first and obvious answer is, Every- 
body knows. And everybody that is not blind does know to 
a certain extent. We have a special sense-organ for appreci- 
ating light, whereas we have none for electricity. Neverthe- 
less, we must admit that we really know very little about the 
intimate nature of light very little more than about elec- 
tricity. But we do know this, that light is a form of energy ; 
and, moreover, that it is energy rapidly alternating between 
the static and the kinetic forms that it is, in fact, a special 
kind of energy of vibration. We are absolutely certain that 
light is a periodic disturbance in some medium, periodic both 
in space and time that is to say, the same appearances regu- 
larly recur at certain equal intervals of distance at the same 
time, and also present themselves at equal intervals of time 
at the same place ; that, in fact, it belongs to the class 
of motions called by mathematicians undulatory or wave 

Now how much connection between electricity and light 
have we perceived in this glance into their natures? Not 
much truly. It amounts to about this : That on the one 
hand electrical energy may exist in either of two forms 
the static form, when insulators are electrically strained by 
having had electricity driven partially through them (as in 
the Leyden jar), which strain is a form of energy, because 
of the tendency to discharge and do work ; and the kinetic 
form, where electricity is moving bodily along through con- 
ductors, or whirling round and round inside them, which 
motion of electricity is a form of energy, because the con- 
ductors and whirls can attract or repel each other and thereby 
do work. 

On the other hand, light is the rapid alternation of energy 
from one of these forms to the other the static form where 
the medium is strained, to the kinetic form when it moves. 
It is just conceivable then that the static form of the energy 
of light is electro- static that is, that the medium is electrically 
strained and that the kinetic form of the energy of light is 
electro-kinetic that is, that the motion is not ordinary motion, 


but electrical motion in fact, that light is an electrical vibra- 
tion, not a material one. 

On November 5 last year there died at Cambridge a man in 
the full vigour of his faculties such faculties as do not appear 
many times in a century whose chief work had been the 
establishment of this very fact, the discovery of the link con- 
necting light and electricity, and the proof for I believe that it 
amounts to a proof- that they are different manifestations of 
one and the same class of phenomena, that light is, in fact, an 
electro-magnetic disturbance. The premature death of James 
Clerk Maxwell is a loss to science which appears at present 
utterly irreparable, for he was engaged in researches that no 
other man can hope as yet adequately to grasp and follow out ; 
but fortunately it did not occur till he had published his book 
on 'Electricity and Magnetism,' one of those immortal pro- 
ductions which exalt one's idea of the mind of man, and which 
has been mentioned by competent critics in the same breath 
as the ' Principia ' itself. 

The main proof of the electro-magnetic theory of light is 
this : The rate at which light travels has been measured 
many timer, and is pretty well known. The rate at which 
an electro-magnetic wave disturbance would travel, if such 
could be generated (and Mr Fitzgerald, of Dublin, thinks 
he has proved that it cannot be generated directly by any 
known electrical means), can be also determined by calcula- 
tion from electrical measurements. The two velocities agree 

The first glimpse of this splendid generalisation was caught 
in 1845, five-and-thirty years ago, by that prince of pure ex- 
perimentalists, Michael Faraday. His reasons for suspecting 
some connection between electricity and light are not clear to 
us in fact, they could not have' been clear to him ; but he 
seems to have felt a conviction that if he only tried long 
enough, and sent all kinds of rays of light in all possible direc- 
tions across electric and magnetic fields in all sorts of media, 
he must ultimately hit upon something. Well, this is very 
nearly what he did. With a sublime patience and persever- 
ance which remind one of the way Kepler hunted down guess 
after guess in a different field of research, Faraday combined 
electricity, or magnetism, and light in all manner of ways, and 


at last he was rewarded with a result and a most out-of-the- 
way result it seemed. First, you have to get a most powerful 
magnet, and very strongly excite it ; then you have to pierce 
its two poles with holes, in order that a beam of light may 
travel from one to the other along the lines of force ; then, as 
ordinary light is no good, you must get a beam of plane 
polarised light and send it between the poles. But still no 
result is obtained until, finally, you interpose a piece of a rare 
and out-of-the-way material which Faraday had himself dis- 
covered and made, a kind of glass which contains borate of 
lead, and which is very heavy or dense, and which must be 
perfectly annealed. 

And now, when all these arrangements are completed, what 
is seen is simply this, that if an analyser is arranged to stop 
the light and make the field quite dark before the magnet is 
excited, then directly the battery is connected and the magnet 
called into action a faint and barely perceptible brightening 
of the field occurs, which will disappear if the analyser be 
slightly rotated. [The experiment was shown.] Now, no 
wonder that no one understood this result. Faraday himself 
did not understand it at all. He seems to have thought that 
the magnetic lines of force were rendered luminous, or that the 
light was magnetised ; in fact he was in a fog, and had no idea 
of its real significance. Nor had any one. Continental phil- 
osophers experienced some difficulty and several failures 
before they were able to repeat the experiment. It was, in 
fact, discovered too soon, and before the scientific world was 
ready to receive it, and it was reserved for Sir William 
Thomson briefly, but very clearly, to point out, and for Clerk 
Maxwell more fully to develop, its most important conse- 

This is the fundamental experiment on which Clerk Max- 
well's theory of light is based ; but of late years many fresh 
facts and relations between electricity and light have been 
discovered, and at the present time they are tumbling in in 
great numbers. 

It was found by Faraday that many other transparent 
media besides heavy glass would show the phenomenon if 
placed between the poles, only in a less degree ; and the very 
important observation that air itself exhibits the same phenom- 


enon, though to an exceedingly small extent, has just been 
made by Kundt and Rontgen in Germany. 

Dr Kerr, of Glasgow, has extended the result to opaque 
bodies, and has shown that if light be passed through mag- 
netised iron its plane is rotated. The film of iron must be 
exceedingly thin, because of its opacity ; and hence, though 
the intrinsic rotating power of iron is undoubtedly very great, 
the observed rotation is exceedingly small and difficult to 
observe ; and it is only by very remarkable patience and care 
and ingenuity that Dr Kerr has obtained his result. Mr 
Fitzgerald, of Dublin, has examined the question mathemati- 
cally, and has shown that Maxwell's theory would have 
enabled Dr Kerr's result to be predicted. 

Another requirement of the theory is that bodies which are 
transparent to light must be insulators or non-conductors of 
electricity, and that conductors of electricity are necessarily 
opaque to light. Simple observation amply confirms this. 
Metals are the best conductors, and are the most opaque bodies 
known. Insulators such as glass and crystals are transparent 
whenever they are sufficiently homogeneous, and the very 
remarkable researches of Professor Graham Bell in the last few 
months have shown that even ebonite, one of the most opaque 
insulators to ordinary vision, is certainly transparent to some 
kinds of radiation, and transparent to no small degree. 

[The reason why transparent bodies must insulate, and why 
conductors must be opaque, was here illustrated by mechanical 

A further consequence of the theory is that the velocity of 
light in a transparent medium will be affected by its electrical 
strain constant ; in other words, that its refractive index will 
bear some close but not yet quite ascertained relation to its 
specific inductive capacity. Experiment has partially con- 
firmed this, but the confirmation is as yet very incomplete. 

But there are a number of results not predicted by theory, 
and whose connection with the theory is not clearly made out. 
We have the fact that light falling on the platinum electrode 
of a voltameter generates a current, first observed, I think, by 
Sir W. K. Grove ; at any rate it is mentioned in his * Correla- 
tion of Forces ' extended by Becquerel and Robert Sabine to 
other substances, and now being extended to fluorescent and 


other bodies by Professor Minchin. And finally for I must 
be brief we have the remarkable action of light on selenium. 
This fact was discovered accidentally by an assistant in the 
laboratory of Mr Willoughby Smith, who noticed that a piece 
of selenium conducted electricity very much better when light 
was falling upon it than when it was in the dark. The light 
of a candle is sufficient, and instantaneously brings down the 
resistance to something like one-fifth of its original value. 

This is the phenomenon which, as you know, has been 
utilised by Professor Graham Bell in that most ingenious and 
striking invention, the photophone. 

I have now trespassed long enough upon your patience, but 
I must just allude to what may very likely be the next strik- 
ing popular discovery, and that is the transmission of light by 
electricity. I mean the transmission of such things as views 
and pictures by means of the electric wire. It has not yet 
been done, but it seems already theoretically possible, and it 
may very soon be practically accomplished. 

After Hertz. 

Substance of a lecture by Prof. Oliver Lodge, Ashmolean 
Society, Oxford, June 3, 1889. l 

For now wellnigh a century we have had a wave-theory of 
light ; and a wave-theory of light is certainly ;rue. It is 
directly demonstrable that light consists of waves of some 
kind or other, and that these waves travel at a certain well- 
known velocity, seven times the circumference of the earth 
per second, taking eight minutes on the journey from the sun 
to the earth. This propagation in time of an undulatory dis- 
turbance necessarily involves a medium. If waves setting out 
from the sun exist in space eight minutes before striking our 
eyes, there must necessarily be in space some medium in which 
they exist and which conveys them. Waves we cannot have 
unless they be waves in something. 

i Based on a report in the (London) ' Electrician/ September 6, 1889. 


No ordinary medium is competent to transmit waves at 
anything like the speed of light ; hence the luminiferous 
medium must be a special kind of substance, and it is called 
the ether. The luminiferous ether it used to be called, because 
the conveyance of light was all it was then known to be capable 
of ; but now that it is known to do a variety of other things 
also, the qualifying adjective may be dropped. 

Wave motion in ether light certainly is ; but what does one 
mean by the term wave ? The popular notion is, I suppose, 
of something heaving up and down, or perhaps of something 
breaking on the shore in which it is possible to bathe. But 
if you ask a mathematician what he means by a wave, he will 
probably reply that the simplest wave is 
# = asin (pt-nx\ 

and he might possibly refuse to give any other answer. And 
in refusing to give any other answer than this, or its equivalent 
in ordinary words, he is entirely justified ; that is what is 
meant by the term wave, and nothing less general wonld be 

Translated into ordinary English, the phrase signifies " a dis- 
turbance periodic both in space and time." Anything thus 
doubly periodic is a wave ; and all waves whether in air as 
sound waves, or in ether as light waves, or on the surface of 
water as ocean waves are comprehended in the definition. 

What properties are essential to a medium capable of trans- 
mitting wave motion ? Roughly we may say two elasticity 
and inertia. Elasticity in some form, or some equivalent of 
it, in order to be able to store up energy and effect recoil ; 
inertia, in order to enable the disturbed substance to overshoot 
the mark and oscillate beyond its place of equilibrium to and 
fro. Any medium possessing these two properties can transmit 
waves, and unless a medium possesses these properties in some 
form or other, or some equivalent for them, it may be said 
with moderate security to be incompetent to transmit waves. 
But if we make this latter statement one must be prepared 
to extend to the terms elasticity and inertia their very largest 
and broadest signification, so as to include any possible kind 
of restoring force and any possible kind of persistence of 
motion respectively. 

These matters may be illustrated in many ways, but perhaps 


a simple loaded lath or spring in a vice will serve well enough. 
Pull aside one end, and its elasticity tends to make it recoil ; 
let it go, and its inertia causes it to overshoot its normal 
position : both causes together cause it to swing to and fro 
till its energy is exhausted. A regular series of such springs 
at equal intervals in space, set going at regular intervals of 
time one after the other, gives you at once a wave motion and 
appearance which the most casual observer must recognise 
as such. A series of pendulums will do just as well. Any 
wave-transmitting medium must similarly possess some form 
of elasticity and of inertia. 

But now proceed to ask what is this ether which in the 
case of light is thus vibrating? What corresponds to the 
elastic displacement and recoil of the spring or pendulum? 
What corresponds to the inertia whereby it overshoots its 
mark? Do we know these properties in the ether in any 
other way ? 

The answer, given first by Clerk Maxwell, and now reiter- 
ated and insisted on by experiments performed in every im- 
portant laboratory in the world, is 

The elastic displacement corresponds to electro -static charge 
(roughly speaking, to electricity). 

The inertia corresponds to magnetism. 

This is the basis of the modern electro-magnetic theory of 
light. Now let me illustrate electrically how this can be. 

The old and familiar operation of charging a Leyden jar 
the storing up of energy in a strained dielectric any electro- 
static charging whatever is quite analogous to the drawing 
aside of our flexible spring. It is making use of the elasticity 
of the ether to produce a tendency to recoil. Letting go the 
spring is analogous to permitting a discharge of the jar per- 
mitting the strained dielectric to recover itself, the electro- 
static disturbance to subside. 

In nearly all the experiments of electro - statics ethereal 
elasticity is manifest. 

Next consider inertia. How would one illustrate the fact 
that water, for instance, possesses inertia the power of per- 
sisting in motion against obstacles the power of possessing 
kinetic energy? The most direct way would be to take a 
stream of water and try suddenly to stop it. Open a water- 


tap freely and then suddenly shut it. The impetus or 
momentum of the stopped water makes itself manifest by a 
violent shock to the pipe, with which everybody must be 
familiar. The momentum of water is utilised by engineers in 
the <c water-ram." 

A precisely analogous experiment in electricity is what 
Faraday called " the extra current." Send a current through 
a coil of wire round a piece of iron, or take any other arrange- 
ment for developing powerful magnetism, and then suddenly 
stop the current by breaking the circuit. A violent flash 
occurs if the stoppage is sudden enough, a flash which means 
the bursting of the insulating air partition by the accumulated 
electro-magnetic momentum. 

Briefly, we may say that nearly all electro-magnetic experi- 
ments illustrate the fact of ethereal inertia. 

Now return to consider what happens when a charged con- 
ductor (say a Leyden jar) is discharged. The recoil of the 
strained dielectric causes a current, the inertia of this current 
causes it to overshoot the mark, and for an instant the charge 
of the jar is reversed : the current now flows backwards and 
charges the jar up as at first ; again flows the current, and so 
on, discharging and charging the jar with rapid oscillations 
until the energy is all dissipated into heat. The operation is 
precisely analogous to the release of a strained spring, or to 
the plucking of a stretched string. 

But the discharging body thus thrown into strong electrical 
vibration is embedded in the all-pervading ether, and we have 
just seen that the ether possesses the two properties requisite 
for the generation and transmission of waves viz., elasticity, 
and inertia or density ; hence, just as a tuning-fork vibrating 
in air excites aerial waves or sound, so a discharging Leyden 
jar in ether excites ethereal waves or light. 

Ethereal waves can therefore be actually produced by direct 
electrical means. I discharge here a jar, and the room is for 
an instant filled with light. With light, I say, though you 
can see nothing. You can see and hear the spark indeed, 
but that is a mere secondary disturbance we can for the 
present ignore I do not mean any secondary disturbance. I 
mean the true ethereal waves emitted by the electric oscilla- 
tion going on in the neighbourhood of this recoiling dielectric. 


You pull aside the prong of a tuning-fork and let it go : vibra- 
tion follows and sound is produced. You charge a Leyden jar 
and let it discharge : vibration follows and light is excited. 

It is light just as good as any other light. It travels at the 
same pace, it is reflected and refracted according to the same 
laws ; every experiment known to optics can be performed 
with this ethereal radiation electrically produced, and yet you 
cannot see it. Why not ? For no fault of the light ; the fault 
(if there be a fault) is in the eye. The retina is incompetent 
to respond to these vibrations they are too slow. The vibra- 
tions set up when this large jar is discharged are from a hun- 
dred thousand to a million per second, but that is too slow for 
the retina. It responds only to vibrations between 4000 bil- 
lions and 7000 billions per second. The vibrations are too 
quick for the ear, which responds only to vibrations between 
40 and 40,000 per second. Between the highest audible and 
the lowest visible vibrations there has been hitherto a great 
gap, which these electric oscillations go far to fill up. There 
has been a great gap simply because we have no intermediate 
sense-organ to detect rates of vibration between 40,000 and 
4,000,000,000,000,000 per second. It was, therefore, an un- 
explored territory. Waves have been there all the time in 
any quantity, but we have not thought about them nor at- 
tended to them. 

It happens that I have myself succeeded in getting electric 
oscillations so slow as to be audible. The lowest I have got 
at present are 125 per second, and for some way above this 
the sparks emit a musical note ; but no one has yet succeeded 
in directly making electric oscillations which are visible, though 
indirectly every one does it by lighting a candle. 

Here, however, is an electric oscillator which vibrates 300 
million times a second, and emits ethereal waves a yard long. 
The whole range of vibrations between musical tones and some 
thousand millions per second is now filled up. 

These electro-magnetic waves have long been known on the 
side of theory, but interest in them has been immensely quick- 
ened by the discovery of a receiver or detector for them. The 
great though simple discovery by Hertz of an " electric eye," 
as Sir W. Thomson calls it, makes experiments on these waves 
for the first time possible, or even easy. We have now a sort 


of artificial sense - organ for their appreciation an electric 
arrangement which can virtually "see" these intermediate 
rates of vibration. 

The Hertz receiver is the simplest thing in the world 
nothing but a bit of wire, or a pair of bits of wire, adjusted 
so that when immersed in strong electric radiation they give 
minute sparks across a microscopic air-gap. 

The receiver I have here is adapted for the yard-long waves 
emitted from this small oscillator ; but for the far longer waves 
emitted by a discharging Leyden jar an excellent receiver is 
a gilt wall-paper or other interrupted metallic surface. The 
waves falling upon the metallic surface are reflected, and in 
the act of reflection excite electric currents, which cause sparks. 
Similarly, gigantic solar waves may produce aurorae ; and 
minute waves from a candle do electrically disturb the retina. 

The smaller waves are, however, far the most interesting 
and the most tractable to ordinary optical experiments. From 
a small oscillator, which may be a couple of small cylinders 
kept sparking into each other end to end by an induction coil, 
waves are emitted on which all manner of optical experiments 
can be performed. 

They can be reflected by plain sheets of metal, concentrated 
by parabolic reflectors, refracted by prisms, concentrated by 
lenses. I have at the College a large lens of pitch, weighing 
over 3 cwt, for concentrating them to a focus. They can be 
made to show the phenomenon of interference, and thus have 
their wave lengths accurately measured. They are stopped by 
all conductors, and transmitted by all insulators. Metals are 
opaque, but even imperfect insulators, such as wood or stone, 
are strikingly transparent, and waves may be received in one 
room from a source in another, the door between the two being 

The real nature of metallic opacity and of transparency has 
long been clear in Maxwell's theory of light, and these elec- 
trically produced waves only illustrate and bring home the 
well-known facts. The experiments of Hertz are in fact the 
apotheosis of that theory. 

Thus, then, in every way Maxwell's brilliant perception of 
the real nature of light is abundantly justified ; and for the 
first time we have a true theory of light, no longer based upon 


analogy with sound, nor upon a hypothetical jelly or elastic 

Light is an electro-magnetic disturbance of the ether. Optics 
is a branch of electricity. Outstanding problems in optics are 
being rapidly solved now that we have the means of definitely 
exciting light with a full perception of what we are doing, and 
of the precise mode of its vibration. 

It remains to find out how to shorten down the waves to 
hurry up the vibration until the light becomes visible. No- 
thing is wanted but quicker modes of vibration. Smaller oscil- 
lators must be used very much smaller oscillators not much 
bigger than molecules. In all probability one may almost 
say certainly ordinary light is the result of electric oscillation 
in the molecules of hot bodies, or sometimes of bodies not hot 
as in the phenomenon of phosphorescence. 

The direct generation of visible light by electric means, so 
soon as we have learnt how to attain the necessary frequency 
of vibration, will have most important practical consequences. 

For consider our present methods of making artificial light : 
they are both wasteful and ineffective. 

We want a certain range of oscillation, between 7000 and 
4000 billion vibrations per second, no other is useful to us, 
because no other has any effect upon our retina ; but we do 
not know how to produce vibrations of this rate. We can 
produce a definite vibration of one or two hundred or thousand 
per second in other words, we can excite a pure tone of 
definite pitch ; and we can command any desired range of 
such tones continuously by means of bellows and a keyboard. 
We can also (though the fact is less well known) excite 
momentarily definite ethereal vibrations of some millions per 
second, as I have explained ; but we do not at present seem to 
know how to maintain this rate quite continuously. To get 
much faster rates of vibration than this, we have to fall back 
upon atoms. We know how to make atoms vibrate, it is 
done by what we call "heating" the substance; and if we 
could deal with individual atoms unhampered by others, it is 
possible that we might get a pure and simple mode of vibra- 
tion from them. It is possible, but unlikely ; for atoms, even 
when isolated, have a multitude of modes of vibration special 
to themselves, of which only a few are of practical use to us, 


and we do not know how to excite some without also the 
others. However, we do not at present even deal with indi- 
vidual atoms ; we treat them crowded together in a compact 
mass, so that their modes of vibration are really infinite. 

We take a lump of matter, say a carbon filament or a piece 
of quicklime, and by raising its temperature we impress upon 
its atoms higher and higher modes of vibration, not transmut- 
ing the lower into the higher, but superposing the higher upon 
the lower, until at length we get such rates of vibration as our 
retina is constructed for, and we are satisfied. But how waste- 
ful and indirect and empirical is the process ! We want a small 
range of rapid vibrations, and we know no better than to make 
the whole series leading up to them. It is as though, in order 
to sound some little shrill octave of pipes in an organ, we are 
obliged to depress every key and every pedal, and to blow a 
young hurricane. 

I have purposely selected as examples the more perfect 
methods of obtaining artificial light, wherein the waste radia- 
tion is only useless, and not noxious. But the old-fashioned 
plan was cruder even than this : it consisted simply in setting 
something burning, whereby not the fuel but the air was 
consumed ; whereby also a most powerful radiation was pro- 
duced, in the waste waves of which we were content to sit 
stewing, for the sake of the minute almost infinitesimal 
fraction of it which enabled us to see. 

Every one knows now, however, that combustion is not a 
pleasant or healthy mode of obtaining light ; but everybody 
does not realise that neither is incandescence a satisfactory 
and unwasteful method, which is likely to be practised for 
more than a few decades, or perhaps a century. 

Look at the furnaces and boilers of a great steam-engine 
driving a group of dynamos, and estimate the energy ex- 
pended ; and then look at the incandescent filaments of the 
lamps excited by them, and estimate how much of their 
radiated energy is of real service to the eye. It will be as 
the energy of a pitch-pipe to an entire orchestra. 

It is not too much to say that a boy turning a handle could, 
if his energy were properly directed, produce quite as much 
real light as is produced by all this mass of mechanism and 
consumption of material. There might, perhaps, be something 


contrary to the laws of nature in thus hoping to get and util- 
ise some specific kind of radiation without the rest ; but Lord 
Eayleigh has shown in a short communication to the British 
Association at York that it is not so, and that therefore we 
have a right to try to do it. 

We do not yet know how, it is true, but it is one of the 
things we have got to learn. 

Any one looking at a common glowworm must be struck 
with the fact that not by ordinary combustion, nor yet on the 
steam-engine and dynamo principle, is that easy light pro- 
duced. Very little waste radiation is there from phosphor- 
escent things in general. Light of the kind able to affect the 
retina is directly emitted ; and for this, for even a large supply 
of this, a modicum of energy suffices. 

Solar radiation consists of waves of all sizes, it is true ; but 
then solar radiation has innumerable things to do besides 
making things visible. The whole of its energy is useful. In 
artificial lighting nothing but light is desired ; when heat is 
wanted it is best obtained separately by combustion. And so 
soon as we clearly recognise that light is an electrical vibra- 
tion, so soon shall we begin to beat about for some mode of 
exciting and maintaining an electrical vibration of any required 
degree of rapidity. When this has been accomplished, the 
problem of artificial lighting will have been solved. 




(Extracted from the l Journal of the Telegraph? Neio York, 
Sept. 1, 1877.) 

WASHINGTON, March 11, 1876. 

DEAR SIR, In answer to your letter of the 7th inst, I have 
to say that the discrepancy which exists as to the question 
whether electricity passes at the surface or through the whole 
capacity of the rod has arisen principally from experiments on 
galvanic electricity, which, having little or no repulsive energy, 
passes through the whole substance of the rod, and also from 
experiments in which a very large quantity of frictional elec- 
tricity is transmitted through a small wire : in this case the 
metal is resolved into its elements and reduced to an 
impalpable powder. 

In the case, however, of the transmission of atmospheric 
electricity through a rod of sufficient size to transmit the dis- 
charge freely, there can be no doubt that it tends to pass at 
the surface, the thickness of the stratum of electricity varying 
with the diameter of the rod and the amount and the intensity 
of the charge. 

To test this by actual experiment I made the following ar- 
rangement : through a gun-barrel about 2 feet in length a 
copper wire was passed, the ends projecting. The middle of 
the wire in the barrel was coiled into the form of a magnetis- 
ing spiral, and the ends of the gun-barrel were closed with 
plugs of tinfoil, so as to make a perfect metallic connection 
between the wire and the barrel. On the outside of the barrel 
another magnetising spiral was placed, the whole arrangement 
being shown in the sketch. 


A powerful charge was now sent through the copper wire 
from a Leyden jar of about two gallons' capacity. The needle 
within the barrel showed not the least sign of magnetism, 
while the one on the outside was strongly magnetic. 

From this experiment I conclude that a gas-pipe can convey 
an ordinary charge of electricity from the clouds as well as a 
solid rod of the same diameter. 

The repulsive energy of the electrical discharge at right 
angles to the axis remains of the same intensity as in the case 
of a statical charge. This I have shown to be the case by 
drawing sparks of considerable intensity from a conductor, one 
end of which was connected with the ground while sparks 
were thrown on the other end from a large prime conductor. 
This spark is of a peculiar character, for though it gives a 
pungent shock and sets fire to combustible substances, such as 
an electrical pistol, it does not affect a sensitive gold-leaf elec- 
trometer. The fact is, it consists of two sparks, the one 
negative and the other positive. The rod during the trans- 
mission of the electricity through it is charged + at the upper 
end, and immediately in advance of this point it is charged - 
by induction, and the electricity passes through it in the dis- 
charge in the form of a series of + and waves. Yours very 
truly, JOSEPH HENRY, Sec. Smithsonian Inst. 

Prof. E. C. KEDZIE, Lansing, Michigan. 

WASHINGTON, April 15, 1876. 

DEAR SIR, Your letter was received by due course of mail, 
but a press of business connected with the preparation of the 
Annual Keport for 1875 and the Lighthouse Board has pre- 
vented an earlier reply. 

I have now to say that, as far as I know, I am the only person 
who has made a special study of the conduction of frictional 
electricity in regard to lightning-rods. It has long been estab- 
lished by Coulomb and others that the electricity of a charged 
conductor exists in a thin stratum at the surface, and this is a 


necessary consequence of the repulsion of electricity for itself, 
every particle being repelled from every other as far as possible. 
From this it was hastily assumed that electricity in motion 
also moves at the surface ; but this was an inference without 
physical proof until I commenced the investigation. I found 
from a series of experiments that frictional electricity that is, 
electricity of repulsive energy, such as that from the clouds 
does pass at the surface, but that galvanic electricity, the kind 
to which Faraday, Daniell, De La Rive, and others refer, 
passes through the whole capacity of the conductor. This 
latter fact, however, was previously established by others. I 
further found that whenever a charge of electricity was thrown 
on a rod explosively, however well connected the rod was with 
the earth, it gave off sparks in the course of its length sufficient 
to fire an electric pistol and light flocculent substances. I also 
found that, in sending a powerful discharge from a battery of 
nine jars through a wide plate, no electricity passed along the 
middle of the plate, but that it was accumulated in its passage 
at the edges. 

From all my study of this subject I do not hesitate to say 
that the plan I have given of lightning-rods is the true one, 
and that a tube of a sufficient degree of thickness serves to 
conduct the electricity as well as a solid mass, provided the 
thickness is sufficient to give free conduction. A very heavy 
charge sent through a wire frequently deflagrates it, but no 
discharge from the clouds, of which I have any knowledge, has 
ever sufficed to deflagrate a gas-pipe of an inch in diameter. 

The plan of increasing the surface of a rod by converting the 
metal into a ribbon is objectionable. It tends to increase the 
power of the lateral discharge, and gives no increase of con- 
ducting power. 

Another fallacy is much insisted on viz., the better conduc- 
tion of copper than iron. It is true that copper is a better 
conductor of galvanic electricity, which pervades the whole 
mass, but in regard to frictional electricity the difference in 
conducting capacity is too small to be of any importance. Iron 
is sufficiently good in regard to conduction, and withstands 
deflagration better than copper : besides this, it is much 
cheaper. Yours truly, JOSEPH HENRY. 

Prof. R. C. KEDZIE. 



Substance of a lecture by Prof. H. A. Eowland, American 
Institute of Electrical Engineers, May 22, 1889. l 

How great, then, the difference between a current of water 
and a current of electricity ! The action of the former is con- 
fined to the interior of the tube, while that of the latter ex- 
tends to great distances on all sides, the whole of the space being 
agitated by the formation of an electric current in any part. 
To show this agitation, I have here two large frames with coils 
of wire around them. They hang face to face about 6 feet 
apart. Through one I discharge this Ley den jar, and imme- 
diately you see a spark at a break in the wire of the other coil, 
and yet there is no apparent connection between the two. I 
can carry the coils 50 feet or more apart, and yet, by suitable 
means, I can observe the disturbances due to the current in 
the first coil. 

The question is forced upon us as to how this action takes 
place. How is it possible to transmit so much power to such a 
distance across apparently unoccupied space ? According to 
our modern theories of physics, there must be some medium 
engaged in this transmission. We know that it is not the air, 
because the same effects take place in a vacuum, and therefore 
we must fall back on that medium which transmits light, and 
which we have named the ether that medium which is sup- 
posed to extend unaltered throughout the whole of space, 
whose existence is very certain, but whose properties we have 
yet but vaguely conceived. 

I cannot in the course of one short hour give even an idea 
of the process by which the minds of physicists have been led 
to this conclusion, or the means by which we have finally 
completely identified the ether which transmits light with the 
medium which transmits electrical and magnetic disturbances. 
The great genius who first identified the two is Maxwell, 
whose electro-magnetic theory of light is the centre around 

1 Based on reports in the (London) ' Electrician,' June 21 and 28, 


which much scientific thought is to-day revolving, and which we 
regard as one of the greatest steps by which we advance nearer 
to the understanding of matter and its laws. It is this great 
discovery of Maxwell which allows me to attempt to explain 
to you the wonderful events which happen everywhere in 
space when one establishes an electric current in any other 

In the first place, we discover that the disturbance does not 
take place in all portions of space at once, but proceeds out- 
ward from the centre of the disturbance with a velocity exactly 
equal to the velocity of light ; so that when I touch these 
wires together so as to complete the circuit of yonder battery, 
I start a wave of ethereal disturbance which passes outward 
with a velocity of 185,000 miles per second, and continues to 
pass outwards for ever, or until it reaches the bounds of the 
universe. And yet none of our senses informs us of what has 
taken place unless sharpened by the use of suitable instru- 
ments. Thus, in the case of these two coils of wire, suspended 
near each other, when the wave from the primary disturbance 
reaches the second coil we perceive the disturbance by means 
of the spark formed at the break in the coil. Should I move 
the coils farther apart, the spark in the second coil would be 
somewhat delayed, but the distance of 185,000 miles would be 
necessary before this delay could amount to as much as one 
second. Hence the effects we observe on the earth take place 
so nearly instantaneously that the interval of time is very 
difficult to measure, amounting in the present case to only 
T5 oo ooo oo th of a second. 

It is impossible for me to prove the existence of this interval, 
so infinitesimal is it, but I can at least show you that waves 
have something to do with the action observed. For instance, 
I have here two tuning-forks mounted on sounding-boxes and 
tuned to exact unison. I sound one and then stop its vibra- 
tions with my hand ; instantly you hear that the other is in 
vibration, caused by the waves of sound in the air between the 
two. When, however, I destroy the unison by fixing this piece 
of wax on one of the forks, the action ceases. 

Now, this combination of a coil of wire and a Leyden jar 
forms a vibrating system of electricity, and its time of vibra- 
tion is about 10,000,000 times a second. Here is another 


combination of coil and jar, the same as the first, and therefore 
its time of vibration is the same. You see how well the 
experiment works, because the two are in unison. But let me 
take away this second Leyden jar, thus destroying the unison, 
and you see that the sparks instantly cease. Eeplacing it, the 
sparks reappear. Adding another on one side, they disappear 
again, only to reappear when the system is made symmetrical 
by placing two on each side. 

This experiment and that of the tuning-forks have an exact 
analogy to one another. In each we have two vibrating 
systems connected by a medium capable of transmitting 
vibrations, and they both come under the head of what we 
know as sympathetic vibrations. In the one case, we have 
two mechanical tuning-forks connected by the air ; in the 
other, two pieces of apparatus, which we might call electrical 
tuning-forks, connected by the ether. The vibrations in one 
case can be seen by the eye or heard by the ear, but in the 
other case they can only be perceived when we destroy them 
by making them produce a spark. The fact that we are able 
to increase the effect by proper tuning demonstrates that 
vibrations are concerned in the phenomenon. This can, how- 
ever, be separately demonstrated by examining the spark by 
means of a revolving mirror, when we find that it is made up 
of many successive sparks corresponding to the successive 
backward and forward movements of the current. 

Thus, in the case of a charged Leyden jar whose inner and 
outer coatings have been suddenly joined by a wire, the elec- 
tricity flows back and forth along the wire until all the energy 
originally stored up in the jar has expended itself in heating 
the wire or the air where the spark takes place, and in gener- 
ating waves of disturbance in the ether which move outward 
into space with the velocity of light. These ethereal waves we 
have demonstrated by letting them fall on this coil of wire, 
causing the electrical disturbance to manifest itself by electric 

I have here another more powerful arrangement for produc- 
ing electro-magnetic waves of very long wave length, each one 
being about 500 miles long. It consists of a coil within which 
is a bundle of iron wires. On passing a powerful alternating 
current through the coil the iron wires are rapidly magnetised 


and demagnetised, and send forth into space a system of electro- 
magnetic waves at the rate of 360 in a second. 

Here also I have another piece of apparatus for sending out 
the same kind of electro-magnetic waves, and on applying a 
match we start it also into action. But the last apparatus is 
tuned to so high a pitch that the waves are only ^oooo i ncn 
long, and 55,000,000,000,000 are given out in one second. These 
short waves are known by the name of light and radiant heat, 
though the name radiation is more exact. Placing any body 
near the lamp so that the radiation can fall on it, we observe 
that when the body absorbs the rays it is heated by them. Is 
it not possible for us to get some substance to absorb the long 
(or electro-magnetic) waves of disturbance, and so obtain a 
heating effect 1 I have here such a substance in the shape of a 
sheet of copper, which I fasten on the face of a thermopile, 
and I hold it where these waves are strongest. As I have 
anticipated, great heat is generated by their absorption, and 
soon the plate of copper becomes very warm, as we see by this 
thermometer, by feeling it with the hand, or even by the steam 
from water thrown upon it. In this experiment the copper 
had not touched the coil or the iron wire core, although if it 
did they are very much cooler than itself. The heat has been 
produced by the absorption of the waves in the same way as a 
blackened body absorbs the rays of shorter wave length from 
the lamp. 

In these experiments, so far, the wave-like nature of the 
disturbance has not been proved. We have caused electric 
sparks, and have heated the copper plate across an interval of 
space, but have not in either of these cases proved experi- 
mentally the progressive nature of the disturbance. 

A ready means of experimenting on the waves, obtaining 
their wave length and showing their interferences, has hitherto 
been wanting. This deficiency has been recently supplied by 
Prof. Hertz, of Carlsruhe. 

I scarcely know how to present this subject to a non- technical 
audience and make it clear how a coil of wire with a break in 
it can be used to measure the velocity and length of ethereal 
waves. However, I can but try. If the waves moved very 
slowly, we could readily measure the time the first coil took to 
affect the second, and show that this time was longer as the 


distance was greater. But it is absolutely inappreciable by any 
of our instruments, and another method must be found. To 
obtain the wave length Prof. Hertz used several methods, but 
that by the formation of stationary waves is the most easily 
grasped. I hold in my hand one end of a spiral spring, which 
makes a heavy and flexible rope. As I send a wave down it, 
you see that it is reflected at the farther end, and returns again 
to my hand. If, however, I send a succession of waves down 
the rope, the reflected waves interfere with the direct ones, and 
divide the rope into a succession of nodes and loops which you 
now observe. So, a series of sound waves, striking on a wall, 
forms a system of stationary waves in front of the wall. 
Indeed we can use any waves for this purpose, even ethereal 
waves. With this in view Prof. Hertz established his apparatus 
in front of a reflecting wall, and observed the nodes and loops 
by the sparks produced in a ring of wire, somewhat resembling 
the coil I have been using, but much smaller. It is impossible 
for me to repeat this experiment before you, as it is a very 
delicate one, and the sparks produced are almost microscopic. 
Indeed I should have to erect an entirely different apparatus, 
as the waves from the one before me are nearly a quarter-mile 
long. To produce shorter waves we must use apparatus very 
much smaller tuned, as it were, to a higher pitch, so that 
several stationary waves, or nodes and loops, of a few yards 
long could be obtained in the space of this room. 

The testing coil would then be moved to different parts of the 
room, and the nodes would be indicated by the disappearance 
of the sparks, and the loops by the greater brightness of them. 
The presence of stationary waves would thus be proved, and 
their half -wave length found from the distance from node 
to node, for stationary waves can always be considered as 
produced by the interference of two waves advancing in op- 
posite directions. 

The closing of a battery circuit, then, and the establishment 
of a current of electricity in a wire, is a very different process 
from the formation of a current of water in a pipe, though 
after the first shock the laws of the flow of the two are very 
much alike. Furthermore, the medium around the current of 
electricity has very strange properties, showing that it is ac- 
companied by a disturbance throughout space. The wire is 


but the core of the disturbance, which latter extends indefin- 
itely in all directions. 

One of the strangest things about it is that we can calculate 
with perfect exactness the velocity of the wave propagation 
and the amount of the disturbance at every point and at any 
instant of time ; but as yet we cannot conceive of the details of 
the mechanism which is concerned in the propagation of an 
electric current. In this respect our subject resembles all 
other branches of physics in the partial knowledge we have of 
it. We know that light is the undulation of the luminiferous 
ether, and yet the constitution of the latter is unknown. We 
know that the atoms of matter can vibrate with purer tones 
than the most perfect piano, and yet we cannot even conceive 
of their constitution. We know that the sun attracts the 
planets with a force whose law is known, and yet we fail to 
picture to ourselves the process by which it takes our earth 
within its grasp at the distance of many millions of miles and 
prevents it from departing for ever from its life-giving rays. 
Science is full of this half -knowledge. 

So far we have considered the case of alternating electric 
currents in a wire connecting the inner and outer coatings of a 
Leyden jar. The invention of the telephone, by which sound 
is carried from one point to another by means of electrical 
waves, has forced into prominence the subject of these waves. 
Furthermore, the use of alternating currents for electric light- 
ing brings into play the same phenomenon. Here, again, the 
difference between a current of water and a current of elec- 
tricity is very marked. A sound wave, traversing the water 
in the tube, produces a to-and-fro current of water at any 
given point. So, in the electrical vibration along a wire, the 
electricity moves to and fro along it in a manner somewhat 
similar to the water, but with this difference : the disturbance 
from the water-motion is confined to the tube, and the oscilla- 
tion of the water is greatest in the centre of the tube ; while in 
the case of the electric current the ether around the wire is dis- 
turbed, and the oscillation of the current is greatest at the 
surface of the wire and least in its centre. The oscillations in 
the water take place in the tube without reference to the 
matter outside the tube, whereas the electric oscillations in the 
wire are entirely dependent on the surrounding space, and the 


velocity of the propagation is nearly independent of the nature 
of the wire, provided it is a good conductor. 

We have then in the case of electrical waves along a wire a 
disturbance outside the wire and a current within it, and the 
equations of Maxwell allow us to calculate these with perfect 
accuracy and give all the laws with respect to them. 

We thus find that the velocity of propagation of the waves 
along a wire, hung far away from other bodies and made of 
good conducting material, is that of light, or 185,000 miles per 
second ; but when it is hung near any conducting matter, like 
the earth, or enclosed in a cable and sunk into the sea, the 
velocity becomes much less. When hung in space, away from 
other bodies, it forms, as it were, the core of a system of waves 
in the ether, the amplitude of the disturbance becoming less 
and less as we move away from the wire. But the most 
curious fact is that the electric current penetrates only a 
short distance into the wire, being mostly confined to the 
surface, especially where the number of oscillations per second 
is very great. 

The electrical waves at the surface of a conductor are thus, 
in some respects, very similar to the waves on the surface of 
water. The greatest motion in the latter case is at the surface, 
while it diminishes as we pass downwards and soon becomes 
inappreciable. Furthermore, the depth to which the disturb- 
ance penetrates into the water increases with increase of the 
length of the wave, being confined to very near the surface for 
very short waves. So the disturbance in the copper penetrates 
deeper as the waves and the time of oscillation are longer, and 
the disturbance is more nearly confined to the surface as the 
waves become shorter. 1 

There are very many practical applications of these theor- 
etical results for electric currents. The most obvious one is 
to the case of conductors for the alternating currents used 

1 A striking illustration of this skin-deep penetration of high-voltage 
electricity was communicated by Lord Armstrong to Sir William Thom- 
son (now Lord Kelvin) at the Newcastle meeting of the British Associa- 
tion in 1889. A bar of steel about a foot long, which Lord Armstrong 
was holding in his hand, was allowed accidentally to short circuit the 
two terminals of a dynamo giving an alternate current of 85 amperes, at 
a difference of potential of 103 volts. He instantly felt a sensation of 


in producing the electric light. We find that when these are 
larger than about half an inch diameter they should be re- 
placed by a number of conductors less than half an inch dia- 
meter, or by strips about a quarter of an inch thick, and of 
any convenient width. 

Prof. Oliver Lodge has recently drawn attention to another 
application of these results that is, to lightning-rods. Al- 
most since the time of Franklin there have been those who 
advocated the making of lightning-rods hollow in order to in- 
crease the surface for a given amount of copper. We now 
know that these persons had no reason for their belief, as they 
simply drew the inference that electricity at rest is on the 
surface. Neither were the advocates of the solid rods quite 
correct, for they reasoned that electricity in a state of steady 
flow occupies the whole area of the conductor equally. The 
true theory, we now know, indicates that neither party was 
entirely correct, and that the surface is a very important factor 
in the case of a current of electricity so sudden as that from a 
lightning discharge. But increase of surface can best be ob- 
tained by multiplying the number of conductors, rather than 
making them flat or hollow. Theory indicates that the current 
penetrates only one-tenth the distance into iron that it does 
into copper. As the iron has seven times the resistance of 
copper, we should need seventy times the surface of iron that 
we should of copper. Hence I prefer copper wire about 
a quarter of an inch diameter and nailed directly to the house 
without insulators, and passing down the four corners, around 
the eaves, and over the roof, for giving protection from light- 
ning in all cases where a metal roof and metal down-spouts do 
not accomplish the same purpose. 

Whether the discharge of lightning is oscillatory or not does 
not enter into the question, provided it is only sufficiently 
sudden. I have recently solved the mathematical problem of 
the electric oscillations along a perfectly conducting wire join- 
burning and dropped the bar. His fingers were badly blistered, though 
on examining the bar a few seconds afterwards it was found to be quite 
cold. This proved that the action lay at the surface, and had not time to 
sensibly penetrate the substance of the bar. There were two little 
hollows burned out of the metal at the points where it touched the 
dynamo terminals. J. J. F, 


ing two infinite and perfectly conducting planes parallel to 
each other, and find that there is no definite time of oscillation, 
but that the system is capable of vibrating in any time in 
which it is originally started. The case of lightning between 
a cloud of limited extent and the earth along a path through 
the air of great resistance is a very different problem. Both 
the cloud and the path of the electricity are poor conductors, 
which tends to lengthen the time. If I were called on to 
estimate as nearly as possible what took place in a flash of 
lightning, I would say that I did not believe that the discharge 
was always oscillating, but more often consisted of one or more 
streams of electricity at intervals of a small fraction of a sec- 
ond, each one continuing for not less than TOSOUO second. An 
oscillating current with 100,000 reversals per second would 
penetrate about ^ inch into copper and g^ inch into iron. 
The depth for copper would constitute a considerable propor- 
tion of a wire J- inch diameter, and as there are other con- 
siderations to be taken into account, I believe it is scarcely 
worth while making tubes, or flat strips, for such small 

It is almost impossible to draw proper conclusions from ex- 
periments on this subject in the laboratory, such as those of 
Prof. Oliver Lodge. 1 The time of oscillation of the current in 
most pieces of laboratory apparatus is so very small, being 
often the yoooooo^o f a second, that entirely wrong inferences 
may be drawn from them. As the size of the apparatus in- 
creases, the time of oscillation increases in the same propor- 
tion, and changes the whole aspect of the case. I have given 
ro^onu ^ a second as the shortest time a lightning-flash could 
probably occupy. I strongly suspect it is often much greater, 
and thus departs even further from the laboratory experiments 
of Prof. Lodge, who has, however, done very much towards 
drawing attention to this matter and showing the importance 
of surface in this case. All shapes of the rod with equal sur- 
face are not, however, equally efficient. Thus, the inside 
surface of a tube does not count at all. Neither do the corru- 
gations on a rod count for the full value of the surface they 

1 For Prof. Lodge's views see his paper, 'Jour. Inst. Elec. Engs.,' 
vol. xix. p. 352, and the very interesting discussion thereupon. 
J. J. F. 


expose, for the current is not distributed uniformly over the 
surface ; but I have recently proved that rapidly alternating 
currents are distributed over the surface of very good conduc- 
tors in the same manner as electricity at rest would be dis- 
tributed over them, so that the exterior angles and corners 
possess much more than their share of the current, and corru- 
gations on the wire concentrate the current on the outer 
angles and diminish it in the hollows. Even a flat strip has 
more current on the edges than in the centre. 

For these reasons, shape, as well as extent of surface, must 
be taken into account, and strips have not always an advan- 
tage over wires for quick discharges. 

The fact that the lightning-rod is not melted on being struck 
by lightning is not now considered as any proof that it has done 
its work properly. It must, as it were, seize upon the discharge, 
and offer it an easier passage to the earth than any other. Such 
sudden currents of electricity we have seen to obey very dif- 
ferent laws from continuous ones, and their tendency to stick 
to a conductor and not fly off to other objects depends not only 
on having them of small resistance, but also on having what we 
call the self-induction as small as possible. This latter can be 
diminished by having the lightning-rod spread sideways as 
much as possible, either by rolling it into strips, or better, by 
making a network of rods over the roof with several connections 
to the earth at the corners, as I have before described. 

Thus we see that the theory of lightning-rods, which appeared 
so simple in the time of Franklin, is to-day a very complicated 
one, and requires for its solution a very complete knowledge of 
the dynamics of electric currents. In the light of our present 
knowledge the frequent failure of the old system of rods is no 
mystery, for I doubt if there are a hundred buildings in the 
country properly protected from lightning. With our modern 
advances, perfect protection might be guaranteed in all cases, 
if expense were no object. 

We have now considered the case of oscillations of electricity 
in a few cases, and can turn to that of steady currents. The 
closing of an electric circuit sends ethereal waves throughout 
space, but after the first shock the current flows steadily with- 
out producing any more waves. However, the properties of 
the space around the wire have been permanently altered, as 


we have already seen. Let us now study these properties more 
in detail. I have before me a wire in which I can produce a 
powerful current of electricity, and we have seen that the 
space around it has been so altered that a delicately suspended 
magnetic needle cannot remain quiet in all positions, but 
stretches itself at right angles to the wire, the north pole 
tending to revolve around it in one direction and the south 
pole in the other. This is a very old experiment, but we now 
regard it as evidence that the properties of the space around 
the wire have been altered rather than that the wire acts on 
the magnet from a distance. 

Put, now, a plate of glass around the wire, the latter being 
vertical and the former with its plane horizontal, and pass a 
powerful current through the wire. On now sprinkling iron 
filings on the plate they arrange themselves in circles around 
the wire, and thus point out to us the celebrated lines of mag- 
netic force of Faraday. Using two wires with currents in the 
same direction we get these other curves, and, testing the forces 
acting on the wire, we find that they are trying to move towards 
each other. 

Again, pass the currents in the opposite directions and we 
get these other curves, and the currents repel each other. If 
we assume that the lines of force are like rubber bands which 
tend to shorten in the direction of their length and repel each 
other sideways, Faraday and Maxwell have shown that all mag- 
netic attractions and repulsions are explained. The property 
which the presence of the electric current has conferred on the 
ether is then one by which it tends to shorten in one direction 
and spread out in the other two directions. 

We have thus done away with action at a distance, and have 
accounted for magnetic attraction by a change in the inter- 
vening medium, as Faraday partly did almost fifty years ago. 
For this change in the surrounding medium is as much a 
part of the electric current as anything that goes on within 
the wire. 

To illustrate this tension along the lines of force, 1 have con- 
structed this model, which represents the section of a coil of 
wire with a bar of iron within it. The rubber bands represent 
the lines of force which pass around the coil and through the 
iron bar, as they have an easier passage through the iron than 


the air. As we draw the bar down and let it go, you see that 
it is drawn upward and oscillates around its position of equili- 
brium until friction brings it to rest. Here, again, I have a 
coil of wire with an iron bar within it with one end resting on 
the floor. As we pass the current, and the lines of magnetic 
force form around the coil and pass through the iron, it is lifted 
upwards, although it weighs 24 lb., and oscillates around its 
position of equilibrium exactly the same as though it were 
sustained by rubber bands as in the model. The rubber bands 
in this case are invisible to our eye, but our mental vision 
pictures them as lines of magnetic force in the ether drawing 
the bar upward by their contractile force. This contractile 
force is no small quantity, as it may amount, in some cases, to 
one or even two hundred pounds to the square inch, and 
thus rivals the greatest pressure which we use in our steam- 

Thus the ether is, to-day, a much more important factor in 
science than the air we breathe. We are constantly surrounded 
by the two, and the presence of the air is manifest to us all ; 
we feel it, we hear by its aid, and we even see it under favour- 
able circumstances, and the velocity of its motion as well as the 
amount of moisture it carries is a constant topic of conversation. 
The ether, on the other hand, eludes all our senses, and it is 
only with imagination, the eye of the mind, that its presence 
can be perceived. By its aid in conveying the vibrations we 
call light we are enabled to see the world around us ; and by its 
other motions, which cause magnetism, the mariner steers his 
ship through the darkest night when the heavenly bodies are 
hid from view. When we speak in a telephone, the vibrations 
of the voice are carried forward to the distant point by waves 
in the ether, there again to be resolved into the sound waves 
of the air. When we use the electric light to illuminate our 
streets, it is the ether which conveys the energy along the 
wires as well as transmits it to our eye after it has assumed the 
form of light. We step upon an electric street-car and feel it 
driven forward with the power of many horses, and again it is 
the ether whose immense force we have brought under our 
control and made to serve our purpose no longer a feeble, un- 
certain sort of medium, but a mighty power, extending through- 
out all space, and binding the whole universe together. 





Substance of a paper by Prof. E. Branly, of the Catholic 
University of Paris. 1 

The object of this article is to describe the first results 
obtained in an investigation of the variation or resistance of a 
large number of conductors under various electrical influences. 
The substances which up to the present have presented the 
greatest variations in conductivity are the powders or filings 
of metals. The enormous resistance offered by metal in a 
state of powder is well known ; indeed, if we take a somewhat 
long column of very fine metallic powder, the passage of the 
current is completely stopped. The increase in the electrical 
conductivity by pressure of powdered conducting substances is 
also well known, and has had various practical applications. 
The variations of conductivity, however, which occur on sub- 
jecting conducting bodies to various electrical influences have 
not been previously investigated. 

The Effect of Electric Sparks. Let us take a circuit compris- 
ing a single cell, a galvanometer, and some powdered metal 
enclosed in an ebonite tube of one square centimetre cross section 
and a few centimetres long. Close the extremities of the tube 
with two cylindrical copper tubes pressing against the powdered 
metal and connected to the rest of the circuit. If the powder 
is sufficiently fine, even a very sensitive galvanometer does 
not show any evidence of a current passing. The resistance is 
of the order of millions of ohms, although the same metal 
melted or under pressure would only offer (the dimensions 
being the same) a resistance equal to a fraction of an ohm. 
There being, therefore, no current in the circuit, a Leyden 

1 Based on reports in the (London) ' Electrician/ June 26 and August 
21, 1891. 


jar is discharged at some little distance off, when the abrupt 
and permanent deflection of the galvanometer needle shows 
that an immediate and a permanent reduction of the resistance 
has been caused. The resistance of the metal is no longer to 
be measured in millions of ohms, but in hundreds. Its con- 
ductivity increases with the number and intensity of the 

Some 20 or 30 centimetres from a circuit comprising some 
metallic filings contained in an ebonite cup, let us place a 
hollow brass sphere, 15 to 20 centimetres in diameter, insu- 
lated by a vertical glass support. The filings offer an enormous 
resistance and the galvanometer needle remains at zero. But 
if we bring an electrified stick of resin near the sphere, a little 
spark will pass between the stick and the sphere, and imme- 
diately the needle of the galvanometer is violently jerked and 
then remains permanently deflected. On some fresh filings 
being placed in the ebonite cup, the resistance of the circuit 
will again keep the needle at zero. If now the charged brass 
sphere is touched with the finger, there is a minute discharge 
and the galvanometer needle is again deflected. With a few 
accumulators the experiment can easily be made without a 
galvanometer. The circuit consists of the battery, some 
metallic powder, a platinum wire, and a mercury cup. The re- 
sistance of the powder is so high that the interruption of the 
circuit takes place without any sparking of the mercury cup. 
If now a Leyden jar is discharged in the neighbourhood of the 
circuit the powder is rendered conducting, the platinum wire 
immediately becomes red hot, and a violent spark occurs on 
breaking the circuit. 

The influence of the spark decreases as the distance increases, 
but its influence is observable several metres away from the 
powder, even with a small Wimshurst machine. Repeating 
the spark increases the conductivity ; in fact, with certain 
substances successive sparks produce successive jerks, and a 
gradually increasing and persistent deflection of the galvan- 
ometer needle. 

Influence of a Conductor traversed by Condenser Discharges. 
While using the Wimshurst machine it was noticed that the 
reduction in the resistance of the filings frequently took place 
before discharge. This led me to the following experiment : 


Take a long brass tube, one end of which is close to the circuit 
containing the metallic powder ; its other end, several metres 
distant from the circuit, is fairly close to a charged Leyden 
jar. A spark takes place and the conductor is charged. At 
the same instant, the conductivity of the metallic powder is 
greatly increased. 

The following arrangement, owing to its efficacy, conven- 
ience, and regularity of action, was used by me in most of 
my researches, and I shall briefly call it the A arrangement 
(%. 1). 

The source of electricity is a two-plate Holtz machine driven 
at from 100 to 400 revolutions. A sensitive substance is intro- 
duced into one of the arms of a Wheatstone bridge, or into the 
circuit of a single Daniell cell at a dis- 
u^ 11 LIL1 j Uil tance of some 10 metres from the Holtz 

I , Q Q-J I j machine. Between the discharge knobs of 

the machine and the Wheatstone bridge, 
and connected to the former, there are 
two insulated brass tubes, A A', running 
A' parallel to one another 40 centimetres 

apart. The Leyden jars usually attached 
to a Holtz machine may be dispensed 
with, the capacity of the long brass tubes 
Fig. 1. being in some measure equivalent to them. 

The knobs s were 1 mm., *5 mm., or -1 mm. 
apart. When the plates were rotated, sparks rapidly succeeded 
each other. Experiments showed that these sparks had no di- 
rect effect at a distance of 10 metres. The two tubes A A' are not 
absolutely necessary ; the diminution of resistance is easily pro- 
duced if only one is employed, and in some cases, indeed, a 
single conductor is more efficacious. An increase in the speed 
of the machine increases its action to a marked extent. The 
sparks at s may be suppressed by drawing the knobs apart, 
but the conductor A will still continue to exert its influence, 
especially if there is a spark-gap anywhere about. 

Effects of Induced Currents. The passage of induced currents 
through a sensitive substance produces similar effects to those 
described above. In one instance an induction coil was taken, 
having two similar wires. The circuit of the secondary wire 
was closed through a tube containing filings, the galvanometer 



being also in circuit. Care was taken to ascertain before intro- 
ducing the filings into the circuit that the currents on make 
and break gave equal and opposite deflections. Filings were 
then introduced into the circuit, the primary being made and 
broken at regular intervals. The following table gives the 
results obtained in the case of zinc filings : 


Galvanometer throws. Galvanometer throws. 

1st closing . . 1 1st opening . . 18 

2nd . . 64 2nd . 100 

3rd . . 146 3rd / 140 

Effects of passing Continuous Currents of High E.M.F. If a 
continuous current of high E.M.F. is employed, it renders 
a sensitive substance conducting. The phenomenon may be 
shown in the following manner. A circuit is made up con- 
sisting of a battery, a sensitive substance, and a galvanometer. 
The E.M.F. of the battery is first 1 volt, then 100 volts, then 1 
volt. Below I give the galvanometer deflections obtained 
with an E.M.F. of 1 volt for three different substances before 
and after the application of the E.M.F. of 100 volts : 

Before application After application 
of current of current. 

16 100 


1 500 

In the case of some measurements taken on a Wheatstone 
bridge, a prism of aluminium filings interposed between two 
copper electrodes offered a resistance of several million ohms 
before a high E.M.F. was applied, but only offered a resistance 
of 350 ohms after the application of this pressure for one 
minute. The time during which the powder should be inter- 
posed in the battery circuit should not be too short. Thus, in 
one instance the application for 10 seconds of 75 mercury 
sulphate cells produced no effect, but their application for 60 
seconds resulted in the resistance being reduced from several 
megohms to 2500 ohms. 

It should be observed that the phenomenon of suddenly in- 
creased conductivity occurs even if the sensitive substance is 



not in circuit with a battery at the time it is influenced. 
Thus, the metallic filings, after having been placed in circuit 
with a Daniell cell, and their high resistance observed, may then 
be completely insulated and submitted in this condition to the 
action of a distant spark, or of a charged rod, or of induced 
currents. If, after this, the filings are replaced in their 
original circuit, the enormous increase in their conductivity 
is immediately apparent. 

The conductivity produced by these various methods takes 
place throughout the whole mass of the 
metallic filings, and in every direction, 
as the following experiment will show. 
A vertical ebonite cup containing alu- 
minium powder (fig. 2) is placed between 
two metal plates A, B ; laterally the pow- 
der is in contact with two short rods 
c, D, which pass through the sides of 
the ebonite cylinder. A and B can be 
connected to two terminals of one of 
the arms of the Wheatstone bridge, 
c and D being free, and vice versa. 
Whatever arrangement is adopted, if a 
battery of 100 cells is joined up for a 
few seconds with one or the other of 
the pairs of terminals, the increase in 

the conductivity is immediately visible in that direction, and 
is found to exist also in the direction at right angles. 

Substances in which Diminution of Resistance has been ob- 
served. The substances in which the phenomenon of the sudden 
increase of conductivity is most easily observed are filings of 
iron, aluminium, copper, brass, antimony, tellurium, cadmium, 
zinc, bismuth, &c. The size of the grains and their nature are 
not the only elements to be considered, for grains of lead of 
the same size, but coming from different quarters, offer at the 
same temperature great differences in resistance (20,000 to 
500,000 ohms). Extremely fine metallic powder, as a rule, 
offers almost perfect resistance to the passage of a current. 
But if we take a sufficiently short column and exert a suffi- 
ciently great pressure, a point is soon reached when the elec- 
trical influence will effect a sudden increase in the conductivity. 


Fig. 2. 



Thus, a layer of copper reduced by hydrogen, which does not 
become conducting under the influence of the electric spark or 
otherwise, will become so on being submitted to a pressure of 
500 grammes to the square centimetre (7 Ib. per square inch). 
Instead of using pressure, I employed as a conductor in some 
experiments a very fine coating of powdered copper spread on 
a sheet of unpolished glass or ebonite E (fig. 3), 7 centimetres 
long and 2 centimetres 
broad. A layer of this 
kind, polished with a 
burnisher, has a very 
variable resistance. 
With a little care one 
can prepare sheets which 
are more or less sensi- 
tive to electrical action. 
Metal powders or 
metal filings are not 
the only sensitive sub- 
stances, as powdered 
galena, which is slightly 
conducting under pres- 
sure, conducts much 
better after having been submitted to electrical influence. 
Powdered binoxide of manganese is not very sensitive unless 
mixed with powdered antimony and compressed. 

Making use of the A arrangement with very short sparks 
at s (fig. 1), the phenomenon of increased conductivity can be 
observed with platinised and silvered glass, also with glass 
covered with gold, silver, and aluminium foil. Some of the 
mixtures employed had the consistency of paste. These were 
mixtures of colza oil and iron, or antimony filings, and of ether 
or petroleum and aluminium, and plumbago, &c. Other mix- 
tures were solid. If we make a mixture of iron filings and 
Canada balsam, melted in a water bath, and pour the paste 
into a little ebonite cup, the ends of which are closed by 
metallic rods, a substance is obtained which solidifies on cool- 
ing. The resistance of such a mixture is lowered from several 
megohms to a few hundred ohms by an electric spark. Similar 
results are obtained with a solid rod composed of fused flowers 

Fig. 3. 


of sulphur and iron or aluminium filings, also by a mixture 
of melted resin and aluminium filings. In the preparation 
of these solid sensitive mixtures, care must be taken that the 
insulating substance should only form a small percentage of 
the whole. 

Some interesting results are also obtained with mixtures of 
sulphur and aluminium, and with resin and aluminium, when 
in a state of powder. When cold these mixtures, as a rule, do 
not conduct either directly or after they have been exposed to 
electrical influences, but they become conducting on combining 
pressure with electrical influences. Thus, a mixture of flowers-of - 
sulphur and aluminium filings in equal volumes was placed in a 
glass tube 24 mm. in diameter. The weight of the mixture was 
20 grammes, and the height of the column 22 mm., with a pres- 
sure of 186 grammes per square centimetre (2j Ib. per square 
inch). The mixture is not conducting, but after exposure to 
electrical influence, obtained by the A arrangement, the resist- 
ance falls to 90 ohms. In a similar manner a mixture of 
selenium and aluminium, placed in a tube 99 mm. long, was 
not conducting until after it was exposed to the combined in- 
fluence of pressure and electricity. 

The following is one of the group of numerous experiments 
of a slightly different character. A mixture of flowers-of - 
sulphur and fine aluminium filings, containing two of sulphur 
to one of aluminium, is placed in a cylindrical glass tube 35 
mm. long. By means of a piston, a pressure of 20 kilogrammes 
per square centimetre (284 Ib. per square inch) was applied. 
It was only necessary to connect the column for 10 seconds to 
the poles of a 25-cell battery, for the resistance originally in- 
finite to be reduced to 4000 ohms. 

The arrangement shown in fig. 4 illustrates another order of 
experiment. Two rods of copper were oxidised in the flame of 
a Bunsen burner, and were then arranged to lie across each 
other, as shown, and were connected to the terminals of the 
arm of a Wheatstone bridge, the high resistance of the circuit 
being due to the layers of oxide. Amongst the many measure- 
ments made, I found, in one case, a resistance of 80,000 ohms, 
which, after exposure to the influence of the electric spark, 
was reduced to 7 ohms. Analogous effects are obtained with 
oxidised steel rods. Another pretty experiment is to place a 




cylinder of copper, with an oxidised hemispherical head, on a 

sheet of oxidised copper. Before exposure to the influence of 

the electric spark, the oxide offers considerable resistance. 

The experiment can be 

repeated several times by 

merely moving the cylin- 

der from one place to 

another on the oxidised 

sheet of copper, thus 

showing that the pheno- 

menon only takes place 

at the point of contact of 

the two layers of oxide. 

It may be worth noting 
that, for most of the sub- 
stances enumerated, an 
elevation of temperature 
diminishes the resistance, but the effect of a rise of tempera- 
ture is transient, and is incomparably less than the effect due 
to currents of high potential. For a few substances the two 
effects are opposed. 

Restoration of Original Resistance. The conductivity caused 
by the various electrical influences lasts sometimes for a long 
period (twenty-four hours or more), but it is always possible to 
make it rapidly disappear, particularly by a shock. 

The majority of substances tested snowed an increase of 
resistance on being shaken previous to being submitted to any 
special electrical influence, but after having been influenced 
the effect of shock is much more marked. The phenomenon is 
best seen with the metallic filings, but it can also be observed 
with metallised ebonite sheets with mixtures of liquid insulators 
and metallic powders, mixtures of metallic filings and insulating 
substances (compressed or not compressed), and finally with 
solid bodies. 

I observed the return to original resistance in the following 
manner : 

The sensitive substance was placed at K (fig. 1), and formed 
part of a circuit which included a Daniell cell and galvanometer. 
At first no current passes. Sparks are then caused at s, and 
the needle of the galvanometer is permanently deflected. On 


smartly tapping the table supporting the ebonite cup in which 
the sensitive substance is contained, the original condition is 
completely restored. When the electric action has been of a 
powerful character, violent blows are necessary. I employed 
for the purpose of these shocks a hammer fixed on the table, 
the blows of which could be regulated. 

With some substances, when feebly electrified, the return 
seemed to be spontaneous, although it was slower than the 
return of the galvanometer needle to equilibrium. This resto- 
ration of the original resistance is attributable to surrounding 
trepidations, as it was only necessary to walk about the room 
at a distance of a few metres, or to shake a distant wall. This 
spontaneous return to original resistance after weak electrical 
action was visible with a mixture of equal parts of fine selenium 
and tellurium powders. The restoration of resistance by shock 
was not observable so long as the electrical influence was at 

After having been submitted to powerful electric action, 
shock does not seem to entirely restore substances to their 
original state ; in fact, the substances generally show greater 
sensitiveness to electric action. Thus, a mixture of colza oil 
and antimony powder being exposed to the influence of arrange- 
ment A, a spark of 5 mm. was at first necessary to break down 
the resistance ; but after the conductivity had been made to 
disappear by means of blows, a spark of only 1 mm. was suffi- 
cient to again render the substance conducting. Finely 
powdered aluminium has an extremely high resistance. A 
vertical column of powdered aluminium 5 mm. long of 4 square 
cms. cross-section, submitted to considerable pressure, com- 
pletely stopped the current from a Daniell cell. The influence 
of arrangement A produced no effect, but, by direct contact 
with a Leyden jar, the resistance was reduced to 50 ohms. The 
effect of shock was then tried, and after this the sparks pro- 
duced by arrangement A were able to reduce the resistance. 

The following experiment is also of the same kind : Alum- 
inium filings placed in a parallelipidic trough completely stopped 
the current from a Daniell cell, and the resistance offered to a 
single cell remained infinite after the trough had been placed 
in the circuit of 25 sulphate of mercury cells for 10 seconds. 
The aluminium was next placed in circuit with a battery of 75 


cells ; a single Daniell cell was then able to send a current 
through the substance. The original resistance was restored 
by shock, but not the original condition of things, since a single 
cell was able to send a current after the aluminium had been 
circuited for 10 seconds with a battery of only 25 cells. I may 
add that if the restoration of resistance was brought about by 
a violent shock, it was necessary to place the aluminium in 
circuit with 75 cells for one minute before the resistance was 
again broken down. 

It must be observed that electrical influence is not always 
necessary to restore conductivity after an apparent return to 
the original resistance, repeated feeble blows being sometimes 
successful in bringing this about. Both in the case of slow 
return by time and sudden return by shock, the original value 
of the resistance is often increased. Eods of Carre carbon, 1 
metre long and 1 mm. in diameter, were particularly noticeable 
for this phenomenon. 

Return to Original Resistance by Temperature Elevation. A 
plate of coppered ebonite rendered conducting by electricity, 
and placed close to a gas-jet, quickly regained its original 
resistance. A solid rod of resin and aluminium, or of sulphur 
and aluminium, rendered conducting by connection to the poles 
of a small battery, will regain its original resistance by shock ; 
but if the conducting state has been caused by powerful means, 
such, for instance, as direct contact with a Leyden jar, shock 
no longer has any effect, at least such a shock as the fragile 
nature of the material can stand. A slight rise of temperature, 
however, has the desired result. By suitably regulating the 
electric action it is possible to get a substance into such a 
condition that the warmth of the fingers suffices to annul con- 

Influence of Surroundings. Electric action gives rise to no 
alteration of resistance when the substance is entirely within a 
closed metal box. The sensitive substance, in circuit with a 
Daniell cell and a galvanometer, is placed inside a brass box 
(fig. 5). The absence of current is ascertained, the circuit 
broken, and the box closed. A Wimshurst machine is then 
worked a little way off, and will be found to have had no 
effect. The same result will be obtained if the circuit is kept 
closed during the time the Wimshurst machine is in operation. 



Fig. 5. 

If a wire connected at some point to the circuit is passed out 
through a hole in the box to a distance of 20 to 50 cms., the 
influence of the Wimshurst machine makes itself felt. On 

tapping the lid to re- 
store resistance, the 
galvanometer needle 
remains deflected so 
long as the sparks 
continue to pass. If, 
however, the wires 
are pushed in so that 
they only project a 
few millimetres, the 
sparks still passing, 
a few taps suffice to 
bring back the needle 
to zero. On touch- 
ing the end of the 
wire with the fingers or a piece of metal, conductivity is imme- 
diately restored. The movements of the galvanometer needle 
were rendered visible in these experiments by looking through 
apiece of wide -mesh wire -gauze with a telescope. The re- 
spective position of the things was reversed ; that is to say, 
a Kuhmkorff coil and a periodically discharged Leyden jar 
were placed inside, and the sensitive substance outside, the 
box, with the same results. 

In some later experiments with a larger metallic case, and 
with the Daniell cell, sensitive substance, delicate galvan- 
ometer, and Wheatstone bridge placed inside, I found that a 
double casing was necessary in order to absolutely suppress all 
effects. A glass covering afforded no protection. 

Considerations on the Mechanism of the Effects produced. 
What conclusions are we to draw from the experiments de- 
scribed ? The substances employed in these investigations 
were not conductors, since the metallic particles composing 
them were separated from each other in the midst of an in- 
sulating medium. It was not surprising that currents of high 
potential, and especially currents induced by discharges, should 
spark across the insulating intervals. But as the conductivity 
persisted afterwards, even for the weakest thermo - electric 


currents, there is some ground for supposing that the insulating 
medium is transformed by the passage of the current, and that 
certain actions, such as shock and rise of temperature, bring 
about a modification of this new state of the insulating body. 
Actual movement of the metallic particles cannot be imagined 
in experiments where the particles in a layer a few millimetres 
thick were fixed in an invariable relative position by extreme 
pressures, reaching at times to more than 100 kilogrammes 
per square cm. (1420 Ib. to the square inch). Moreover, in the 
case of solid mixtures, in which the same variations of re- 
sistance were produced, displacement seems out of the question. 
To explain the persistence of the conductivity after the cessation 
of the electrical influence, are we to suppose in the case of 
metallic filings a partial volatilisation of the particles creating 
a conducting medium between the grains of metal ? In the 
case of mixtures of metallic powders and insulating substances 
agglomerated by fusion, are we to suppose that the thin in- 
sulating layers are pierced by the passage of very small sparks, 
and that the holes left behind are coated with conducting 
material ? If this explication is admissible for induced cur- 
rents, it must hold good for continuous currents. If so, we 
must conclude that these mechanical actions may be produced 
by batteries of only 10 to 20 volts electromotive force, and 
which only cause an insignificant current to pass. The following 
experiment is worth quoting in this connection : 

A circuit was formed by a Daniell cell, a sensitive galvan- 
ometer, and some aluminium filings in an ebonite cup. The 
galvanometer needle remained at zero. The filings were cut 
out of this circuit, and switched for one minute into circuit 
with a battery of 43 sulphate of mercury cells. On being re- 
placed in the first circuit, the filings exhibited high conductivity. 
The result was the same when 10 or 20 cells were employed, or 
when the current was diminished by interposing in the circuit 
a column of distilled water, 40 cm. long and 20 mm. in diameter. 
The cells used (platinum, sulphate of mercury, sulphate of zinc, 
zinc) had a high internal resistance. Thus, 43 cells (60 volts), 
when short circuited, only gave a current of 5 milliamperes. 
The same battery, with the column of distilled water in circuit 
only, caused a deflection of 100 mm. on a scale one metre off, 
with an astatic galvanometer wound with 50,000 turns. We 


can, therefore, see how infinitesimally small the initial current 
must have been when the filings were added to the circuit. The 
battery acted, therefore, essentially by virtue of its electro- 
motive force. 

If mechanical displacement of particles or transportation of 
conducting bodies seem inadmissible, it is probable that there 
is a modification of the insulator itself, the modification per- 
sisting for some time by virtue of a sort of "coercive force." 
An electric current of high potential, which would be com- 
pletely stopped by a thick insulating sheet, may be supposed to 
gradually traverse the very thin dielectric layers between the 
conducting particles, the passage being effected very rapidly if 
the electric pressure is great, and more slowly if the pressure 
is less. 

Increase of Resistance. An increase of resistance was observed 
in these investigations less often than a diminution ; neverthe- 
less, a number of frequently repeated experiments enable me to 
say that increase of resistance is not exceptional, and that the 
conditions under which it takes place are well defined. Short 
columns of antimony or aluminium powder, when subjected to 
a pressure of about 1 kilogramme per square cm. (14'2 Ib. per 
square inch), and offering but a low resistance, exhibited an 
increase of resistance under the influence of a powerful electri- 
fication. Peroxide of lead, a fairly good conductor, always 
exhibited an increase, so also did some kinds of platinised 
glass, while others showed alternate effects. For instance, a 
sheet of platinised glass, which offered a resistance of 700 ohms, 
became highly conducting after 150 sulphate of mercury cells 
had been applied to it for 10 seconds. This condition of con- 
ductivity was annulled by contact with a charged Leyden jar, 
and reappeared after again applying 150 cells for 10 seconds, 
and so on. Similar effects were obtained with a thin layer of a 
mixture of selenium and tellurium poured, when fused, into a 
groove in a sheet of mica placed between two copper plates. 
These alternations were always observed several times in suc- 
cession, and at intervals of several days. 

These augmentations and alternations are in no way incom- 
patible with the hypothesis of a physical modification of the 
insulator by electrical influence. 





It may be desirable to place briefly on record the circum- 
stances under which the following remarkable communication 
was written. 

While revising the last sheets of this work, it occurred to the 
author to ask Sir William Crookes for some particulars of the 
experiments to which he alluded in his ' Fortnightly ' article, 
some passages from which are quoted on pp. 197-199. On April 
22, 1899, Sir William replied as follows : 

DEAR MR FAHIE, The experiments referred to at page 
176 of my 'Fortnightly' article as having taken place "some 
years ago" were tried by Prof. Hughes when experimenting 
with the microphone. 

I have not ceased since then urging on him to publish an 
account of his experiments. I do not feel justified in saying 
more about them, but if you were to write to him, telling him 
what I say, it might induce him to publish. 

It is a pity that a" man who was so far ahead of all other 
workers in the field of wireless telegraphy should lose all the 
credit due to his great ingenuity and prevision. Believe me, 
very truly yours, WILLIAM CROOKES. 

On receipt of this letter I wrote to Prof. Hughes. In reply 
he said : 

" Your letter of 26th instant has brought upon me a flood 
of old souvenirs in relation to my past experiments on aerial 
telegraphy. They were completely unknown to the general 
public, and I feared that the few distinguished men who saw 
them had forgotten them, or at least had forgotten how the 
results shown them were produced. . . . 

"At this late date I do not wish to set up any claim to 


priority, as I have never published a word on the subject ; and 
it would be unfair to later workers in the same field to spring 
an unforeseen claimant to the experiments which they have 
certainly made without any knowledge of my work." 

On second (and my readers will say, wiser) thoughts, Prof. 
Hughes sent me the following letter, in the eliciting of which 
I consider myself especially fortunate and privileged : 

40 LANGHAM STREET, W., April 29, 1899. 

DEAR SIR, In reply to yours of the 26th inst., in which 
you say that Sir William Crookes has told you that he saw 
some experiments of mine on aerial telegraphy in about De- 
cember 1879, of which he thinks I ought to have published an 
account, and of which you ask for some information, I beg to 
reply with a few leading experiments that I made on this 
subject from 1879 up to 1886 : 

In 1879, being engaged upon experiments with my micro- 
phone, together with my induction balance, I remarked that at 
some times I could not get a perfect balance in the induction 
balance, through apparent want of insulation in the coils ; but 
investigation showed me that the real cause was some loose 
contact or microphonic joint excited in some portion of the 
circuit. I then applied the microphone, and found that it gave 
a current or sound in the telephone receiver, no matter if the 
microphone was placed direct in the circuit or placed inde- 
pendently at several feet distance from the coils, through which 
an intermittent current was passing. After numerous experi- 
ments, I found that the effect was entirely caused by the 
extra current, produced in the primary coil of the induction 

Further researches proved that an interrupted current in 
any coil gave out at each interruption such intense extra cur- 
rents that the whole atmosphere in the room (or in several 
rooms distant) would have a momentary invisible charge, 
which became evident if a microphonic joint was used as a re- 
ceiver with a telephone. This led me to experiment upon the 
best form of a receiver for these invisible electric waves, which 
evidently permeated great distances, and through all apparent 
obstacles, such as walls, &c. I found that all microphonic con- 
tacts or joints were extremely sensitive. Those formed of a 


hard carbon such as coke, or a combination of a piece of coke 
resting upon a bright steel contact, were very sensitive and 
self -restoring ; whilst a loose contact between metals was 
equally sensitive, but would cohere, or remain in full contact, 
after the passage of an electric wave. 

The sensitiveness of these microphonic contacts in metals 
has since been rediscovered by Mons. Ed. Branly of Paris, 
and by Prof. Oliver Lodge, in England, by whom the name of 
" coherer " has been given to this organ of reception ; but, as 
we wish this organ to make a momentary contact and not 
cohere permanently, the name seems to me ill-suited for the 
instrument. The most sensitive and perfect receiver that I 
have yet made does not cohere permanently, but recovers its 
original state instantly, and therefore requires no tapping or 
mechanical aid to the separation of the contacts after moment- 
arily being brought into close union. 

I soon found that, whilst an invisible spark would pro- 
duce a thermo-electric current in the microphonic contacts 
(sufficient to be heard in the telephone in its circuit), it 
was far better and more powerful to use a feeble voltaic cell 
in the receiving circuit, the microphonic joint then acting 
as a relay by diminishing the resistance at the contact, 
under the influence of the electric wave received through 
the atmosphere. 

I will not describe the numerous forms of the transmitter 
and receiver that I made in 1879, all of which I wrote down in 
several volumes of manuscripts in 1879 (but these have never 
been published), and most of which can be seen here at my 
residence at any time ; but I will confine myself now to a few 
salient points. I found that very sudden electric impulses, 
whether given out to the atmosphere through the extra current 
from a coil or from a frictional electric machine, equally affected 
the microphonic joint, the effect depending more on the sudden 
high potential effect than on any prolonged action. Thus, a 
spark obtained by rubbing a piece of sealing-wax was equally 
effective as a discharge from a Leyden jar of the same poten- 
tial. The rubbed sealing-wax and charged Leyden jar had no 
effect until they were discharged by a spark, and it was evi- 
dent that this spark, however feeble, acted upon the whole 
surrounding atmosphere in the form of waves or invisible rays, 


the laws of which I could not at the time determine. Hertz, 
however, by a series of original and masterly experiments, 
proved in 1887-89 that they were real waves similar to light, 
but of a lower frequency, though of the same velocity. In 
1879, whilst making these experiments on aerial transmission, 
I had two different problems to solve : 1st, What was the true 
nature of these electrical aerial waves, which seemed, whilst 
not visible, to spurn all idea of insulation, and to penetrate all 
space to a distance undetermined. 2nd, To discover the best 
receiver that could act upon a telephone or telegraph instru- 
ment, so as to be able to utilise (when required) these waves 
for the transmission of messages. The second problem came 
easy to me when I found that the microphone, which I had 
previously discovered in 1877-78, had alone the power of 
rendering these invisible waves evident, either in a telephone 
or a galvanometer, and up to the present time I do not know 
of anything approaching the sensitiveness of a microphonic 
joint as a receiver. Branly's tube, now used by Marconi, was 
described in my first paper to the Eoyal Society (May 8, 1878) 
as the microphone tube, filled with loose filings of zinc and 
silver ; and Prof. Lodge's coherer is an ordinary steel micro- 
phone, used for a different purpose from that in which I first 
described it. 1 

During the long - continued experiments on this subject, 
between 1879 and 1886, many curious phenomena came out 
which would be too long to describe. I found that the effect 

1 Prof. Hughes is rightly regarded as the real discoverer of the elec- 
trical behaviour of a bad joint or loose contact, the study of which in his 
hands has given us the microphone ; but as in the case of Hertzian-wave 
effects before Hertz, so, long before Hughes, " mere phenomena of loose 
contact," as Sir George Stokes called them, must have often manifested 
themselves in the working of electrical apparatus. For an interesting 
example see Arthur Schuster's paper read before the British Association 
in 1874 (or abstract, ' Telegraphic Journal,' vol. ii. p. 289), where the 
effects are described as a new discovery in electricity, and disguised 
under the title of the paper, "On Unilateral Conductivity." Schuster 
suspected the cause "Two wires screwed together may not touch each 
other, but be separated by a thin layer of air "but he missed its real 
significance. The phenomenon was a kind of bye-product, cropped up 
while he was engaged on other work, and so was not pursued far enough. 
J. J. F. 


of the extra current in a coil was not increased by having an 
iron core as an electro-magnet the extra current was less 
rapid, and therefore less effective. A similar effect of a 
delay was produced by Leyden-jar discharges. The material 
of the contact-breaker of the primary current had also a great 
effect. Thus, if the current was broken between two or one 
piece of carbon, no effect could be perceived of aerial waves, 
even at short distances of a few feet. The extra current from 
a small coil without iron was as powerful as an intense spark 
from a secondary coil, and at that time my experiments 
seemed to be confined to the use of a single coil of my in- 
duction balance, charged by six Daniell cells. With higher 
battery power the extra current invariably destroyed the in- 
sulation of the coils. 

In December 1879 I invited several persons to see the re- 
sults then obtained. Amongst others who called on me and 
saw my results were 

Dec. 1879. Mr W. H. Preece, F.E.S. ; Sir William Crookes, 
F.RS. ; Sir W. Roberts - Austen, F.RS. ; Prof. W. Grylls 
Adams, F.RS. ; Mr W. Grove. 

Feb. 20, 1880. Mr Spottiswoode, Pres. RS. ; Prof. Huxley, 
F.RS. ; Sir George Gabriel Stokes, F.RS. 

Nov. 7, 1888. Prof. Dewar, F.RS. ; Mr Lennox, Royal 

They all saw experiments upon aerial transmission, as al- 
ready described, by means of the extra current produced from 
a small coil and received upon a semi-metallic microphone, 
the results being heard upon a telephone in connection with 
the receiving microphone. The transmitter and receiver were 
in different rooms, about 60 feet apart. After trying success- 
fully all distances allowed in my residence in Portland Street, 
my usual method was to put the transmitter in operation and 
walk up and down Great Portland Street with the receiver in 
my hand, with the telephone to the ear. 

The sounds seemed to slightly increase for a distance of 60 
yards, then gradually diminish, until at 500 yards I could 
no longer with certainty hear the transmitted signals. What 
struck me as remarkable was that, opposite certain houses, I 
could hear better, whilst at others the signals could hardly be 
perceived. Hertz's discovery of nodal points in reflected waves 


(in 1887-89) has explained to me what was then considered a 

At Mr A. Stroh's telegraph instrument manufactory Mr 
Stroh and myself could hear perfectly the currents trans- 
mitted from the third storey to the basement, but I could not 
detect clear signals at my residence about a mile distant. The 
innumerable gas and water pipes intervening seemed to absorb 
or weaken too much the feeble transmitted extra currents from 
a small coil. 

The President of the Eoyal Society, Mr Spottiswoode, to- 
gether with the two hon. secretaries, Prof. Huxley and Prof. 
G. Stokes, called upon me on February 20, 1880, to see my 
experiments upon aerial transmission of signals. The experi- 
ments shown were most successful, and at first they seemed 
astonished at the results ; but towards the close of three hours' 
experiments Prof. Stokes said that all the results could be 
explained by known electro - magnetic induction effects, and 
therefore he could not accept my view of actual aerial electric 
waves unknown up to that time, but thought I had quite 
enough original matter to form a paper on the subject to be 
read at the Eoyal Society. 

I was so discouraged at being unable to convince them of the 
truth of these aerial electric waves that I actually refused to 
write a paper on the subject until I was better prepared to 
demonstrate the existence of these waves ; and I continued my 
experiments for some years, in hopes of arriving at a perfect 
scientific demonstration of the existence of aerial electric waves 
produced by a spark from the extra currents in coils, or from 
frictional electricity, or from secondary coils. The triumphant 
demonstration of these waves was reserved to Prof. Hertz, who 
by his masterly researches upon the subject in 1887-89 com- 
pletely demonstrated not only their existence but their identity 
with ordinary light, in having the power of being reflected and 
refracted, &c., with nodal points, by means of which the length 
of the waves could be measured. Hertz's experiments were 
far more conclusive than mine, although he used a much less 
effective receiver than the microphone or coherer. 

I then felt it was now too late to bring forward my previous 
experiments ; and through not publishing my results and means 
employed, I have been forced to see others remake the dis- 


coveries I had previously made as to the sensitiveness of the 
microphonic contact and its useful employment as a receiver 
for electric aerial waves. 

Amongst the earliest workers in the field of aerial trans- 
mission I would draw attention to the experiments of Prof. 
Henry, who describes in his work, published by the Smithsonian 
Institute, Washington, B.C., U.S.A., vol. i. p. 203 (date un- 
known, probably about 1850), how he magnetised a needle in 
a coil at 30 feet distance, and magnetised a needle by a dis- 
charge of lightning at eight miles' distance. 1 

Marconi has lately demonstrated that by the use of the 
Hertzian waves and Branly's coherer he has been enabled to 
transmit and receive aerial electric waves to a greater distance 
than previously ever dreamed of by the numerous discoverers 
and inventors who have worked silently in this field. His efforts 
at demonstration merit the success he has received ; and if (as 
I have lately read) he has discovered the means of concentrating 
these waves on a single desired point without diminishing their 
power, then the world will be right in placing his name on the 
highest pinnacle in relation to aerial electric telegraphy. 
Sincerely yours, D. E. HUGHES. 

J. J. FAHIE, Esq., 
Claremont Hill, St Heller's, Jersey. 

In the fifty years (just completed) of a brilliant professorial 
career at Cambridge, Sir George Stokes has given, times out of 
number, sound advice and helpful suggestions to those who 
have sought him ; but in this case, as events show, the great 
weight of his opinion has kept back the clock for many years. 
With proper encouragement in 1879-80 Prof. Hughes would 
have followed up his clues, and, with his extraordinary keenness 

i The ' Polytechnic Review,' March 25, 1843, says : "Professor Henry 
communicated to the American Society that he had succeeded in mag- 
netising needles by the secondary current in a wire more than 220 feet 
distant from the wire through which the primary current, excited by a 
single spark from an electrical machine, was passing." Indeed, Prof. 
Henry noted many cases of what we now call Hertzian-wave effects, but 
what he and every one else in those days thought were only extra- 
ordinary cases of induction. Many experimenters after Henry must have 
observed similar effects. See for example the 'Electrician,' vol. xliii. 
p. 204. J. J. F. 


in research, there can be no doubt that he would have antici- 
pated Hertz in the complete discovery of electric waves, and 
Marconi in the application of them to wireless telegraphy, and 
so have altered considerably the course of scientific history. 

As a recent commentator pithily says : " Hughes's experi- 
ments of 1879 were virtually a discovery of Hertzian waves 
before Hertz, of the coherer before Branly, and of wireless 
telegraphy before Marconi and others." The writer goes on to 
say, " Prof. Hughes has a great reputation already, but these 
latter experiments will add enormously to it, and place him 
among the foremost electricians of all time" 1 praise which, 
knowing the learned professor as I do, I consider none too 



No. 12,039, A.D. 1896. 

Date of Application, 2nd June 1896. Complete Specification 
Left, 2nd Mar. 1897; Accepted, 2nd July 1897. 



I, Guglielmo Marconi, of 71 Hereford Eoad, Bays water, in 
the county of Middlesex, do hereby declare the nature of this 
invention to be as follows : 

According to this invention electrical actions or manifesta- 
tions are transmitted through the air, earth, or water by means 
of electric oscillations of high frequency. 

At the transmitting station I employ a Euhmkorff coil 
having in its primary circuit a Morse key, or other appliance 

1 The < Globe,' May 12, 1899. See also an able and appreciative paper 
by Mr John Munro, in the ' Electrical Review/ vol. xliv. p. 883. 


for starting or interrupting the current, and its pole appliances 
(such as insulated balls separated by small air spaces or high 
vacuum spaces, or compressed air or gas, or insulating liquids 
kept in place by a suitable insulating material, or tubes separ- 
ated by similar spaces and carrying sliding discs) for producing 
the desired oscillations. 

I find that a Kuhmkorff coil, or other similar apparatus, 
works much better if one of its vibrating contacts or brakes on 
its primary circuit is caused to revolve, which causes the 
secondary discharge to be more powerful and more regular, 
and keeps the platinum contacts of the vibrator cleaner and 
preserves them in good working order for an incomparably 
longer time than if they were not revolved. I cause them to 
revolve by means of a small electric motor actuated by the 
current which works the coil, or by another current, or in some 
cases I employ a mechanical (non-electrical) motor. 

The coil may, however, be replaced by any other source of 
high tension electricity. 

At the receiving instrument there is a local battery circuit 
containing an ordinary receiving telegraphic or signalling in- 
strument, or other apparatus which may be necessary to work 
from a distance, and an appliance for closing the circuit, the 
latter being actuated by the oscillations from the transmitting 

The appliance I employ consists of a tube containing con- 
ductive powder, or grains, or conductors in imperfect contact, 
each end of the column of powder or the terminals of the 
imperfect contact or conductor being connected to a metallic 
plate, preferably of suitable length so as to cause the system 
to resonate electrically in unison with the electrical oscillations 
transmitted to it. In some cases I give these plates or con- 
ductors the shape of an ordinary Hertz resonator consisting of 
two semicircular conductors, but with the difference that at 
the spark-gap I place one of my sensitive tubes, whilst the 
other ends of the conductors are connected to small con- 

I have found that the best rules for making the sensitive 
tubes are as follows : 

1st. The column of powder ought not to be long, the effects 
being better in sensitiveness and regularity with tubes contain- 


ing columns of powder or grains not exceeding two-thirds of 
an inch in length. 

2nd. The tube containing the powder ought to be sealed. 

3rd. Each wire which passes through the tube, in order to 
establish electrical communication, ought to terminate with 
pieces of metal or small knobs of a comparatively large surface, 
or preferably with pieces of thicker wire, of a diameter equal 
to the internal diameter of the tube, so as to oblige the powder 
or grains to be corked in between. 

4th. If it is necessary to employ a local battery of higher 
E.M.F. than that with which an ordinarily prepared tube will 
work, the column of powder must be longer and divided into 
several sections by metallic divisions, the amount of powder or 
grains in each section being practically in the same condition 
as in a tube containing a single section. When no oscillations 
are sent from the transmitting instrument the powder or im- 
perfect contact does not conduct the current, and the local 
battery circuit is broken ; but when the powder or imperfect 
contact is influenced by the electrical oscillations, it conducts 
and closes the circuit. 

I find, however, that once started, the powder or contact 
continues to conduct even when the oscillations at the trans- 
mitting station have ceased ; but if it be shaken or tapped, 
the circuit is broken. 

I do this tapping automatically, employing the current 
which the sensitive tube or contact had allowed to begin to 
flow under the influence of the electric oscillations from the 
transmitting instrument to work a trembler (similar to that of 
an electric bell), which hits the tube or imperfect contact, and 
so stops the current and, consequently, its own movement, which 
had been generated by the said current, which by this means 
automatically and almost instantaneously interrupts itself until 
another oscillation from the transmitting instrument repeats 
the process. Whilst for certain purposes I prefer working the 
trembler and the instruments on the same circuit which con- 
tains the sensitive tube or contact, for other purposes I prefer 
working the trembler and the instruments on another circuit, 
which is made to work in accordance with the first by means 
of a relay. It is by means of actions from the current, which 
the sensitive tube or contact allows to pass when the oscilla- 


tions influence it, that I prefer starting the apparatus that has 
to interrupt automatically the same current. 

In order to prevent the action of the self-induction of the 
local circuits on the sensitive tube or contact, and also to de- 
stroy the perturbating effect of the small spark which occurs at 
the breaking of the circuit inside the tube or imperfect contact, 
and also at the vibrating contact of the trembler or at the 
movable contact of the relay, I put in derivation across those 
parts where the circuit is periodically broken a condenser of 
suitable capacity, or a coil of suitable resistance and self-in- 
duction, so that its self-induction may neutralise the self- 
induction of the said circuits ; or preferably I employ in 
derivation on different parts of the circuit conductors or 
so-called semi-conductors of high resistance and small self- 
induction, such as bars of charcoal or preferably tubes contain- 
ing water or other suitable liquid, in electrical communication 
with those conductors of the local circuits which are liable in 
course of self-induction to assume such differences of potential 
as to transmit jerky currents such as would influence the 
sensitive tube or contact so as to prevent its working with 

In some cases, however, I find it suitable to employ an in- 
dependent trembler moved by the current from another 
battery. This trembler is prevented from generating jerking 
or vibrating currents by means of the appliances which I have 
described. This trembler is kept going all the time during 
which one expects oscillations to be transmitted, and, as 
already described, the powder or imperfect contact closes the 
circuit of a local battery, in which are included the instruments 
which one desires to work, for the time during which the elec- 
trical oscillations are transmitted, breaking the circuit in case 
of the mechanical vibrations as soon as the oscillations from the 
transmitting machine cease. When transmitting through the 
air, and it is desired that the signal or electrical action should 
only be sent in one direction, or when it is necessary to trans- 
mit electrical effects to the greatest possible distance without 
wires, I place the oscillation producer at the focus or focal line 
of a reflector directed to the receiving station, and I place the 
tube or imperfect contact at the receiving instrument in a 
similar reflector directed towards the transmitting instrument. 


When transmitting through the earth or water I connect one 
end of the tube or contact to earth and the other end to con- 
ductors or plates, preferably similar to each other, in the air 
and insulated from earth. 

I find it also better to connect the tube or imperfect contact 
to the local circuit by means of thin wires or across two small 
coils of thin and insulated wire preferably containing an iron 

Dated this second day of June 1896. 




I, Guglielmo Marconi, of 67 Talbot Road, Westbourne 
Park, formerly residing at 71 Hereford Eoad, Bays water, in 
the county of Middlesex, do hereby declare the nature of this 
invention and in what manner the same is to be performed to 
be particularly described and ascertained in and by the follow- 
ing statement : 

My invention relates to the transmission of signals by means 
of electrical oscillations of high frequency, which are set up in 
space or in conductors. 

In order that my specification may be understood, and be- 
fore going into details, I will describe the simplest form of my 
invention by reference to figure 1. 

In this diagram A is the transmitting instrument and B is 
the receiving instrument, placed at say J mile apart. 

In the transmitting instrument R is an ordinary induction 
coil (a Ruhmkorff coil or transformer). 

Its primary circuit c is connected through a key D to a battery 
E, and the extremities of its secondary circuit F are connected 
to two insulated spheres or conductors G H fixed at a small 
distance apart. 

When the current from the battery E is allowed to pass 
through the primary of the induction coil, sparks will take 
place between the spheres G H, and the space all around the 


spheres suffers a perturbation in consequence of these electrical 
rays or surgings. 

The arrangement A is commonly called a Hertz radiator, and 
the effects which propagate through space Hertzian rays. 

The receiving instrument B consists of a battery circuit J, 
which includes a battery or cell K, a receiving instrument L, 
and a tube T containing metallic powder or filings, each end 


Fig. 1. 

of the column of filings being also connected to plates or con- 
ductors M N of suitable size, so as to be preferably tuned with 
the length of wave of the radiation emitted from the trans- 
mitting instruments. 

The tube containing the filings may be replaced by an imper- 
fect electrical contact, such as two unpolished pieces of metal 
in light contact, or coherer, &c. 

The powder in the tube T is, under ordinary conditions, a 
non-conductor of electricity, and the current of the cell K can- 
not pass through the instrument ; but when the receiver is 
influenced by suitable electrical waves or radiation the powder 
in the tube T becomes a conductor (and remains so until the 
tube is shaken or tapped), and the current passes through the 

By these means electrical waves which are set up in the 



transmitting apparatus affect the receiving instrument in such 
a manner that currents are caused to circulate in the circuit J, 
and may be utilised for deflecting a needle, which thus re- 
sponds to the impulse coming from the transmitter. 

Figures 2, 3, 4, &c., show various more complete arrange- 
ments of the simple form of apparatus illustrated in figure 1. 

I will describe these figures generally before proceeding to 
describe the improvements in detail. 

Figure 2 is a diagrammatic front elevation of the instru- 
ments of the receiving station, in which k Tc are the plates 
corresponding to M sr in figure 1. g is the battery correspond- 

Fig. 2. 

ing to K, h is the reading instrument corresponding to L, n is a 
relay working the reading instrument h in the ordinary 
manner, p is a trembler or tapper, similar to that of an 
electric bell, which is moved by the current that works the 

Figure 3 is a diagrammatic front elevation of the instru- 
ments at the transmitting station, in which e e are two metallic 
spheres corresponding to Q H in figure 1. 

c is an induction coil corresponding to n. & is a key corres- 
ponding to D, and a is a battery corresponding to E. 

Figure 4 is a vertical section of the radiator or oscillation 
producer mounted in the focal line of a cylindrical parabolic 


reflector / in which a side view of the spheres e e of figure 3 
is given. 

Figure 5 is a full-sized view of the receiving plates Js k and 
sensitive tubey. 

Figure 5A is a modified form of sensitive tube. 

Figure 6 is a modification of the oscillation producer in which 
the spheres e e and d d are mounted in an ebonite tube d 3 . 

Figure 7 is another modification of the oscillation producer 
in which the spheres are substituted by hemispheres. 

Figure 8 is a modified form of receiver in which the plates 
k k are curved instead of being straight. 

Figure 9 is another form of transmitter in which two large 
metallic plates t 2 t 2 are employed. 

Figure 10 shows a modification of the arrangements at the 
transmitting station, and figure 11 a modification of the ar- 
rangements of the receiving station, which enables one to signal 
through obstacles such as hills or mountains. 

Figure 12 shows a detector which is useful for determining 
the proper length of the plates k k of the receivers. 

Figure 13 shows an improved interrupter (make-and-break) 
which is applicable to the induction coil of the transmitter. 

Figure 14 shows a water resistance, the use of which shall be 

My invention relates in great measure to the manner in 
which the above apparatus is made and connected together. 
With some of these forms I am able to obtain Morse signals, 
and to work ordinary telegraphic instruments and other appar- 
atus ; and with modifications of the above apparatus it is 
possible to transmit signals not only through comparatively 
small obstacles such as brick walls, trees, &c., but also through 
or across masses of metal, or hills, or mountains, which may 
intervene between the transmitting and receiving instruments. 

I will first describe my improvements which are applicable 
to the receiving instruments. 

My first improvement consists in automatically tapping or 
disturbing the powder in the sensitive tube, or in shaking the 
imperfect contact, so that immediately the electrical stimulus 
from the transmitter has ceased, the tube or imperfect contact 
regains its ordinary non-conductive state. This part of my 
invention is illustrated in figure 2, in which j represents the 



Fig. 5. 

Fig. SA. 

d 4 

Fig. 6. 


Fig. 7. 

Fig. 9. 

Fig. 8. 

Fig. 10. 

Fig. 11. 


Fig. 12. 

Fig. 13. 


Fig. 14. 


sensitive tube and p the trembler or tapper. The current 
which flows through the sensitive tube or contact, and which 
is commenced under the influence of the electrical oscillations 
from the transmitting instrument, is allowed to actuate 
(directly, or indirectly by means of a relay) the trembler, 
which is similar to an electric bell. This trembler must be so 
arranged, as hereinafter explained, that the effect of the spark- 
ing at its vibrating contacts, and the jerky currents caused by 
self-induction, &c., are neutralised or removed. 

The small hammer of the trembler hits the tube or imperfect 
contact and so stops the current, and consequently its own 
movement, which had been generated by the said current ; and 
by this means the current automatically and almost instantan- 
eously interrupts itself until another oscillation from the 
transmitting instrument again makes the sensitive tube or 
imperfect contact a conductor. 

I find, however, that the current which can be started by 
the sensitive tube or contact is not sufficiently strong to work 
an ordinary trembler and receiving instrument. 

To overcome this difficulty, instead of obliging the current of 
the circuit which contains the sensitive tube or contact to work 
the trembler and instrument, I use the said current for working 
a sensitive relay n (figure 2), which closes and opens the circuit of 
a stronger battery r, preferably of the Leclanche type. This 
current, which is much stronger than the current which runs 
through the sensitive tube or contact, works the trembler and 
other instruments. To prevent the sparks and jerks of current 
which would be caused by the self-induction of the relay from 
interfering with the action of the receiver, certain means must 
be taken similar to those referred to above in reference to the 
trembler or tapper, which will be explained hereafter. In the 
apparatus I have made I have found that the relay n should be 
one possessing small self-induction, and wound to a resistance 
of about 1000 ohms. It should preferably be able to work 
regularly with a current of a milliampere or less. The trembler 
or tapper p on the circuit of the relay n is similar in construc- 
tion to that of a small electric bell, but having a shorter arm. 
I have used a trembler wound to 1000 ohms resistance, having 
a core of good soft iron hollow and split lengthways like most 
electro-magnets used in telegraph instruments. 


The trembler must be carefully adjusted. Preferably the 
blows should be directed slightly upwards, so as to prevent the 
filings from getting caked. In place of tapping the tube the 
powder can be disturbed by slightly moving outwards and 
inwards one or both of the stops of the sensitive tube (see 
figure 5, j l j 2 \ the trembler p (figure 2) being replaced by a 
small electro-magnet or magnets or vibrator whose armature 
is connected to the stop. 

I ordinarily work the receiving instrument A, which may be 
of any description, by a derivation as shown from the circuit, 
which works the trembler p. It can also, however, be worked 
in series with the trembler. 

It is desirable that the receiving instrument, if on a deriva- 
tion of the circuit which includes the trembler or tapper, should 
preferably have a resistance equal to the resistance of the 
trembler p. 

A further improvement consists in the mode of construction 
of the sensitive tube. 

I have noticed that a sensitive tube or imperfect contact, 
such as is shown in figure 1 T, is not perfectly reliable. 

My tube as shown in figure 5 is, if carefully constructed, 
absolutely reliable, and by means of it the relay and trembler 
&c., can be worked with regularity like any other ordinary 
telegraphic instrument. 

In figure 5,j is the sensitive tube containing two metallic 
plugs j 2 connected to the battery circuit, between which is 
placed powder of a conductive material j l . The two plugs 
should preferably be made of silver, or may be two short pieces 
of thick silver wire of the same diameter as the internal 
diameter of the tube^', so as to fit tightly in it. The plugs^' 2 ^' 2 
are joined to two pieces of platinum wire j 3 . The tube is 
closed and sealed on to the platinum wires j 3 at both ends. 
Many metals can be employed for producing the powder or 
filings./ 1 , but I prefer to use a mixture of two or more different 
metals. I find hard nickel to be the best metal, and I prefer 
to add to the nickel filings about four per cent of hard silver 
filings, which increase greatly the sensitiveness of the tube to 
electric oscillations. By increasing the proportion of silver 
powder or grains the sensitiveness of the tube also increases ; 
but it is better for ordinary work not to use a tube of too great 


sensitiveness, as it might be influenced by atmospheric or other 

The sensitiveness can also be increased by adding a very 
small amount of mercury to the filings and mixing up until 
the mercury is absorbed. The mercury must not be in such a 
quantity as to clot or cake the filings : an almost imperceptible 
globule is sufficient for a tube. Instead of mixing the mercury 
with the powder, one can obtain the same effects by slightly 
amalgamating the inner surfaces of the plugs which are to be 
in contact with the filings. Very little mercury must be used, 
just sufficient to brighten the surface of the metallic plugs 
without showing any free mercury or globules. 

The size of the tube and the distance between the two 
metallic stops or plugs may vary under certain limits : the 
greater the space allowed for the powder, the larger or coarser 
ought to be the filings or grains. 

I prefer to make my sensitive tubes of the following size 
the tube j is 1^ inch long and ^ or ^ of an inch internal 
diameter. The length of the stops j* is about of an inch, 
and the distance between the stops or plugs j 2 j 2 is about B a o 
of an inch. 

I find that the smaller or narrower the space is between the 
plugs in the tube, the more sensitive it proves ; but the space 
cannot under ordinary circumstances be excessively shortened 
without injuring the fidelity of the transmission. 

Care must be taken that the plugs J 2 j 2 fit the tube exactly, 
as otherwise the filings might escape from the space between 
the stops, which would soon destroy the action of the sensitive 

The metallic powders ought not to be fine, but rather coarse, 
as can be produced by a large and rough file. 

The powder should preferably be of uniform grain or thick- 

All the very fine powder or the excessively coarse powder 
ought to be removed from it by blowing or sifting. 

It is also desirable that the powder or grains should be dry 
and free from grease or dirt, and the files used in producing the 
same ought to be frequently washed and dried, and used when 

The powder ought not to be compressed between the plugs, 


but rather loose, and in such a condition that when the tube 
is tapped the powder may be seen to move freely. 

The tube j may be sealed, but a vacuum inside it is not 
essential, except the slight vacuum which results from having 
heated it while sealing it. Care should also be taken not to 
heat the tube too much in the centre when sealing it, as it 
would oxidise the surfaces of the silver stops, and also the 
powder, which would diminish its sensitiveness. I have used, 
in sealing the tubes, a hydrogen and air flame. 

A vacuum is, however, desirable, and I have used one of 
about T ^o of an atmosphere obtained by a mercury pump. 

In this case a small glass tube must be joined to a side of the 
tube,/ (6gure 5), which is put in communication with the pump 
and afterwards sealed in the ordinary manner. 

If the sensitive tube has been well made, it should be 
sensitive to the inductive effect of an ordinary electric bell 
when the same is working from one to two yards from 
the tube. 

A sensitive tube well prepared should also instantly in- 
terrupt the current passing through it at the slightest tap or 
shake, provided it is inserted in a circuit in which there is little 
self-induction and small electro-motive force, such as a single 

In order to keep the sensitive tube j in good working order 
it is desirable, but not absolutely necessary, not to allow more 
than one milliampere to flow through it when active. 

If a stronger current is necessary, several tubes may be put 
in parallel, provided they all get shaken by the tapper or 
trembler ; but this arrangement is not always quite as satis- 
factory as the single tube. 

It is preferable, when using sensitive tubes of the type I 
have described, not to insert in the circuit with it more than 
one cell of the Leclanche type, as a higher electro-motive force 
than 1'5 volts is apt to pass a current through the tube, even 
when no oscillations are transmitted. 

I can, however, construct sensitive tubes capable of working 
with a higher electro-motive force. 

Fig. 5A shows one of these tubes. In this tube, instead of 
one space or gap filled with filings, there are several spaces j l j l 9 
separated by plugs of tight-fitting silver wire. A tube thus 


constructed observing also the rules of construction of my 
tubes in general will work satisfactorily if the electro-motive 
force of the battery in circuit with the tube is equal to about 
1*2 volts multiplied by the number of gaps. 

With this tube also it is well not to allow a current of more 
than one milliampere to pass through it. 

Figure 5 also shows the plates Jc , which are joined to each 
end of the sensitive tube, and which correspond to the plates 
M N in figure 1. 

The plates Tc (figure 5) are of copper or other metal, about 
half an inch or more broad, and may be about ^ of an inch 
thick, and preferably of such a length as to be electrically tuned 
with the length of the wave of the electrical oscillations 

The means I adopt for fixing the proper length of the plates 

Tc Tc is as follows : I stick a rectangular strip of tinfoil (see 

figure 12) m about 20 inches long (the length depends on the 

supposed length of the wave that one is measuring), by means 

of a weak solution of gum, on to a glass plate m 1 (figure 12) ; 

then by means of a very sharp penknife or point and ruler I cut 

across the middle of the tinfoil, leaving a mark of division m 2 . 

If this glass plate is held a few feet away from the origin of the 

electrical disturbances, and in such a position that the strips of 

tinfoil are about parallel to the line joining the centres of the two 

spheres in the transmitting apparatus, sparks will jump from 

one strip to the other at m 2 . When the length of the strips of 

tinfoil m has been so adjusted as to approximate to the length 

of wave emitted from the oscillator, the sparking will occur at 

a greater distance from the oscillation producer when the strips 

are of suitable length. By shortening or lengthening the 

strips, therefore, it is easy to find the length most appropriate 

to the length of wave emitted by the oscillation producer. 

The length so found is the proper length for the plates , or 

rather these should be about half an inch shorter on account 

of the length of the sensitive tube j (figure 5) connected 

between them. 

The plates &, tube,/, &c., are fastened to a thin glass tube 0, 
preferably not longer than 12 inches, firmly fixed at one end to 
a firm piece of wood o 2 , or the sensitive tube./ may be fixed 
firmly at both ends i.e., preferably grasped near the ends of 


the tube containing the powder, and not at the ends of the 
tube o o, which serves as support. 

By means of a tube with multiple gaps, as shown in figure 
5A, it is also possible to work the trembler and also the signal- 
ling or other apparatus direct on the circuit which contains the 
sensitive tube, but I prefer when possible to work with the 
single-gap tube and the relay as shown. With a sensitive and 
specially constructed trembler it is also possible to work the 
trembler with the single-gap tube in series with it without a 

In order to increase the distance at which the receiver can 
be actuated by the radiation from the transmitter, I place the 
receiver (i.e., the sensitive tube and plates) in the focal line of 
a cylindrical parabolic reflector I (figure 2), preferably of copper, 
and directed towards the transmitting station. 

In determining the proper length of the plates of the re- 
ceiver by means of the detector shown in figure 12, it is 
desirable to try the detector in the focus or focal line of the 
reflector, because the length of the strips or plates which gives 
the best result in a reflector differs slightly from the length 
which gives the best results without reflectors. 

The reflector I (figure 2) should be preferably in length and 
opening not less than double the length of wave emitted from 
the transmitting instrument. 

It is slightly advantageous for the focal distance of the re- 
flector to be equal to one-fourth or three- fourths of the wave- 
length of the oscillation transmitted. 

The plates Ic (figure 2) may be replaced by tubes or other 
forms of conductors. 

A further improvement has for its object to prevent the 
electrical disturbances which are set up by the trembler and 
other apparatus in proximity or in circuit with the tube from 
themselves restoring the conductivity of the sensitive tube 
immediately after the trembler has destroyed it, as has been 

This I effect by introducing into the circuits at the places 
marked p l , p 2 , q, A 1 , in figure 2 high resistances having as little 
self-induction as possible. The action of the high resistances is 
that, while preventing any appreciable quantity of the current 
from passing through them when the apparatus is working, 


they nevertheless afford an easy path for the currents of high 
tension which would be formed at the moment when the 
circuit is broken, and thus prevent sparking at contacts or 
sudden jerks of currents, which would restore or maintain the 
conductivity of the sensitive tube. 

These coils may conveniently be made by winding the wire 
(preferably of platinoid) on the bight, as it is sometimes 
termed, or double wound, to prevent them producing self- 

In figure 2, p 2 is one of these resistance coils which is inserted 
in a circuit connecting the vibrating contacts of the trembler 
p. I have used in the apparatus a coil which had a resistance 
about four times the resistance of the trembler p. 

p l represents a similar resistance (also of about four times 
the resistance of the trembler) inserted in parallel across 
the terminals of the trembler. 

A similar resistance q, figure 2, is placed in parallel on the 
terminals of the relay n (i.e., the terminals which are connected 
to the circuit containing the sensitive tube). 

The coil q should preferably have a resistance of about three 
or four times the resistance of the relay. 

A similar resistance h l of about four times the resistance of 
the instrument is inserted in parallel across the terminals of 
the instrument. 

In parallel across the terminals of the relay (i.e., correspond- 
ing to the circuit worked by the relay) it is well' to have a 
liquid resistance s constituted of a series of tubes, one of which 
is shown full size in figure 14 partially filled with water acidu- 
lated with sulphuric acid. The number of these tubes in 
series across the said terminals ought to be about ten for a 
circuit of 15 volts, so as to prevent, in consequence of their 
counter electro-motive force, the current of the local battery 
from passing through them, but allowing the high tension jerk 
of current generated at the opening of the circuit in the relay 
to pass smoothly across them without producing perturbating 
sparks at the movable contact of the relay. 

A double-wound platinoid resistance may be used instead of 
the water resistance, provided its resistance be about 20,000 

A resistance similar to h should be inserted in parallel on 


the terminals of any apparatus or resistance which may be 
apt to give self-induction and which is near or connected to 
the receiver. 

Condensers of suitable capacity may be substituted for the 
above-mentioned coils, but I prefer using coils or water re- 

Another improvement has for its object to prevent the high 
frequency oscillations set up across the plates of the receiver 
by the transmitting instrument, which should pass through the 
sensitive tube, from running round the local battery wires 
and thereby weakening their effect on the sensitive tube or 

This I effect by connecting the battery wires to the sensitive 
tube or contact, or to the plates attached to the tube through 
small coils (see k l in the figures) possessing self-induction, 
which may be called choking coils, formed by winding in the 
ordinary manner a short length (about a yard) of thin and 
well-insulated wire round a core (preferably containing iron) 
two or three inches long. 

Another improvement consists in a modified form of the 
plates connected to the sensitive tube, in order to make it 
possible to mount the receiver in an ordinary circular parabolic 
reflector. This part of my invention is illustrated in figure 8, in 
which I is an ordinary concave reflector. In this case the plates 
k k are curved and connected at one end to the sensitive tube^', 
and at the other to a small condenser formed by two metallic 
plates k* of about one inch square or more, facing each other 
with a very thin piece of insulating material k? between them. 
p is the trembler. The condenser may be omitted without 
much altering the effects obtainable. 

The connection to the local circuit is made through two 
small choking coils & l k l as already described. 

The adjustment of the whole is similar to that already de- 
scribed for the other receivers. 

The receiver should be put in such a position as to intercept 
the reflected ring of radiations which exists behind or before 
the focus of the reflector, and ought to be preferably tuned 
with the length of wave of the oscillation transmitted, in similar 
manner to that before described, except that a ring of tinfoil 
with a single cut through it is employed. 


I will now describe my improvements which are applicable 
to the transmitting instruments. 

My first improvement consists in employing four spheres for 
producing the electrical oscillations. 

This part of my invention is illustrated in figure 3, d d, e e, 
and in figure 6, d d, e e. The spheres d d, figure 3, are con- 
nected to the terminals c 1 of the secondary circuit of the induc- 
tion coil c. The spheres d d are carried by insulating supports 
d 1 d l . 

Preferably the supports d 1 consist of plates of ebonite having 
holes to receive the balls, which are fixed by heating them 
sufficiently to fuse the ebonite and then holding them in place 
until they cool, e e are two similar balls on supports e 1 e 1 , 
whose distance apart can be adjusted by ebonite bolts and nuts 
e 2 e 2 acting against other nuts e 3 . e 4 is a flexible membrane, 
preferably of parchment paper, glued to the supports e 1 and 
forming a vessel which is filled with dielectric liquid, prefer- 
ably vaseline-oil slightly thickened with vaseline. 

The oil or insulating liquid between the spheres e e increases 
the power of the radiation, and also enables one to obtain con- 
stant effects, which are not easily obtained if the oil is 

The balls d and e are preferably of solid brass or copper, and 
the distance they should be apart depends on the quantity and 
electro-motive force of the electricity employed, the effect in- 
creasing with the distance (especially by increasing the dis- 
tance between the spheres d and the spheres e) so long as the 
discharge passes freely. With an induction coil giving an 
ordinary 8-inch spark the distance between e and e should be 
from Jj to ^Q of an inch, and the distance between d and e 
about one inch. 

When it is desired that the signal should only be sent in one 
direction, I place the oscillation producer in the focus or focal 
line of a reflector directed to the receiving station. 

/ (figure 3) and / (figure 4) show the cylindrical parabolic 
reflector made by bending a metallic sheet, preferably of brass 
or copper to form, and fixing it to metallic or wooden ribs / l 
(figure 3). 

Other conditions being equal, the larger the balls the greater 
is the distance at which it is possible to communicate. I have 


generally used balls of solid brass of 4 inches diameter, giving 
oscillations of 10 inches length of wave. 

Instead of spheres, cylinders or ellipsoids, &c., may be em- 

Preferably the reflector applied to the transmitter ought to 
be in length and opening the double at least of the length of 
wave emitted from the oscillator. 

If these conditions are satisfied, and with a suitable receiver, 
a transmitter furnished with spheres of 4 inches diameter con- 
nected to an induction coil giving a 10-inch spark will transmit 
signals to two miles or more. 

If a very powerful source of electricity giving a very long 
spark be employed, it is preferable to divide the spark-gap 
between the central balls of the oscillator into several smaller 
gaps in series. This may be done by introducing between the 
big balls smaller ones (of about half an inch diameter) held in 
position by ebonite frames. 

Figure 6 shows a more compact form of oscillation producer. 
In this each pair of balls d and e is fixed by heat or otherwise 
in the end of tubes d 2 of insulating material, such as ebonite or 
vulcanite. The tubes c? 2 fit tightly in another similar tube d 3 
having covers d\ through which pass the rods c? 5 connecting 
the balls d to the conductors. One (or both) of the rods d 3 is 
connected to the ball d by a ball-and-socket joint, and has a 
screw thread upon it working in a nut in the cover d*. By 
turning the rod, therefore, the distance of the balls e apart can 
be adjusted, d 6 are holes in the tube c? 3 , through which the 
vaseline-oil can be introduced into the space between the 
balls e. 

A further improvement consists in causing one of the con- 
tacts of the vibrating brake applied to the induction coil to 
revolve rapidly. 

This improvement has for its object to maintain the plat- 
inum contacts of the interrupter in good working order, and to 
prevent them sticking, &c. 

This part of my invention is illustrated in figure 3 (c 2 , 
c* c). 

I obtain this result by having a revolvable central core e 2 
(figure 3 and figure 13) in the ordinary screw c 3 , which is in 
communication with the platinum contacts. I cause the said 


central core with one of the platinum contacts attached to it 
to revolve by coupling it to a small electric motor c 4 . 

This motor can be worked by the same circuit that works 
the coil, or if necessary by a separate circuit the connections 
are not shown in the drawing. 

By this means the regularity and power of the discharge of 
an ordinary induction coil with a trembler brake are greatly 

The induction coil c (figure 3) may, however, be replaced by 
any other source of high-tension electricity. 

When working with large amounts of energy it is, however, 
better to keep the coil of the transformer constantly working 
for the time during which one is transmitting, and, instead of 
interrupting the current of the primary, interrupting the dis- 
charge of the secondary. 

In this case the contacts of the key should be immersed 
in oil, as otherwise, owing to the length of the spark, the 
current will continue to pass after the contacts have been 

A further improvement has for its object to facilitate the 
focussing of the electric rays. 

This part of my invention is illustrated in figure 7, in which 
a view is given of the modified oscillation producer mounted in 
the focus of an ordinary parabolic reflector/. 

The oscillator in this case is different from the one I have 
previously described, because instead of being constituted of 
two spheres it is made of two hemispheres e e separated by a 
small space filled with oil or other dielectric. The spark be- 
tween the hemispheres takes place in the dielectric from small 
projections at the centres of the hemispheres. The working 
and adjusting of this oscillator are similar to that of the one 
previously described. 

This arrangement may be also solidly mounted in an ebonite 
tube, as shown in figure 6. 

A receiver which may be used with this transmitter is 
shown in figure 8, and has already been described. 

It is not essential to have a reflector at the transmitters and 
receivers, but in their absence the distance at which one can 
communicate is much smaller. 

Figure 9 shows another modified form of transmitter with 


which one can transmit signals to considerable distances with- 
out using reflectors. 

In figure 9, 1 1 are two poles connected by a rope t 1 , to which 
are suspended by means of insulating suspenders two metallic 
plates t 2 t* connected to the spheres e (in oil, or other dielectric, 
as before) and to the other balls t 5 in proximity to the spheres c 1 , 
which are in communication with the coil or transformer c. 
The balls t 3 are not absolutely necessary, as the plates t 2 may 
be made to communicate with the coil or transformer by means 
of thin insulated wires. The receiver I adopt with this trans- 
mitter is similar to it, except that the spheres e are replaced 
by the sensitive tube or imperfect contact j (figure 5), whilst 
the spheres t 3 may be replaced by the choking coils k l in com- 
munication with the local circuit. If a circular-tuned receiver 
of large size be employed, the plates t 2 may be omitted from the 
receiver. I have observed that, other conditions being equal, 
the larger the plates at the transmitter and receiver, and the 
higher they are from earth, and to a certain extent the farther 
apart they are, the greater is the distance at which correspond- 
ence is possible. 

For permanent installations it is convenient to replace the 
plates by metallic cylinders closed at one end, and put over the 
pole like a hat, and resting on insulators. By this arrange- 
ment no wet can come to the insulators, and the effects obtain- 
able are better in wet weather. 

A cone or hemisphere may be used in place of a cylinder. The 
pole employed ought preferably to be dry and tarred. 

Where obstacles, such as many houses or a hill or moun- 
tains, intervene between the transmitter and the receiver, I 
have devised and adopt the arrangement shown in figures 
10 and 11. 

In the transmitting instrument, figure 10, I connect one of 
the spheres d to earth E preferably by a thick wire, and the 
other to a plate or conductor u, which may be suspended on a 
pole v and insulated from earth. Or the spheres d may be 
omitted and one of the spheres e be connected to earth and 
the other to the plate or conductor u. 

At the receiving station, figure 11, I connect one terminal of 
the sensitive tube or imperfect contact./ to earth E, preferably 
also by a thick wire, and the other to a plate or conductor w. 


preferably similar to u. The plate w may be suspended on a 
pole X) and should be insulated from earth. The larger the 
plates of the receiver and transmitter, and the higher from 
the earth the plates are suspended, the greater is the distance 
at which it is possible to communicate at parity of other 

The figure does not show the trembler or tapping arrange- 
ment. k l Jc l are the choking coils, which are connected to the 
battery circuit, as has been explained with reference to the 
previous figures. 

At the receiver it is possible to pick up the oscillations from 
the earth or water without having the plate w. This may be 
done by connecting the terminals of the sensitive tube j to 
two earths, preferably at a certain distance from each other and 
in a line with the direction from which the oscillations are 
coming. These connections must not be entirely conductive, 
but must contain a condenser of suitable capacity, say of one 
square yard surface (parafined paper as dielectric). 

Balloons can also be used instead of plates on poles, provided 
they carry up a plate or are themselves made conductive by 
being covered with tinfoil. As the height to which they may 
be sent is great, the distance at which communication is 
possible becomes greatly multiplied. Kites may also be suc- 
cessfully employed if made conductive by means of tinfoil. 

When working the described apparatus, it is necessary either 
that the local transmitter and receiver at each station should 
be at a considerable distance from each other, or that they 
should be screened from each other by metal plates. It is 
sufficient to have all the telegraphic apparatus in a metal box 
(except the reading instrument), and any exposed part of the 
circuit of the receiver enclosed in metallic tubes which are in 
electrical communication with the box (of course the part of 
the apparatus which has to receive the radiation from the dis- 
tant station must not be enclosed, but possibly screened 
from the local transmitting instrument by means of metallic 

When the apparatus is connected to the earth or water the 
receiver must be switched out of circuit when the local trans- 
mitter is at work, and this may also be done when the apparatus 
is not earthed. 


Having now particularly described and ascertained the 
nature of my said invention, and in what manner the same is 
to be performed, I declare that what I claim is 

1. The method of transmitting signals by means of electrical 
impulses to a receiver having a sensitive tube or other sensitive 
form of imperfect contact capable of being restored with 
certainty and regularity to its normal condition substantially 
as described. 

2. A receiving instrument consisting of a sensitive imperfect 
contact or contacts, a circuit through the contact or contacts, 
and means for restoring the contact or contacts, with certainty 
and regularity, to its or their normal condition after the receipt 
of an impulse substantially as described. 

3. A receiving instrument consisting of a sensitive imperfect 
contact or contacts, a circuit through the contact or contacts, 
and means actuated by the circuit for restoring with certainty 
and regularity the contact or contacts to its or their normal 
condition after the receipt of an impulse. 

4. In a receiving instrument such as is mentioned in claims 
2 and 3, the use of resistances possessing low self-induction, 
or other appliances for preventing the formation of sparks at 
contacts or other perturbating effects. 

5. The combination with the receivers such as are mentioned 
in claims 2 and 3 of resistances or other appliances for pre- 
venting the self-induction of the receiver from affecting the 
sensitive contact or contacts substantially as described. 

6. The combination with receivers such as herein above re- 
ferred to of choking coils substantially as described. 

7. In receiving instruments consisting of an imperfect con- 
tact or contacts sensitive to electrical impulses, the use of 
automatically working devices for the purpose of restoring the 
contact or contacts with certainty and regularity to their 
normal condition after the receipt of an impulse substantially 
as herein described. 

8. Constructing a sensitive non-conductor capable of being 
made a conductor by electrical impulses of two metal plugs or 
theft- equivalents, and confining between them some substance 
such as described. 

9. A sensitive tube containing a mixture of two or more 
powders, grains, or filings, substantially as described. 


10. The use of mercury in sensitive imperfect electrical con- 
tacts substantially as described. 

11. A receiving instrument having a local circuit, including 
a sensitive imperfect electrical contact or contacts, and a relay 
operating an instrument for producing signals, actions, or 
manifestations substantially as described. 

12. Sensitive contacts in which a column of powder or filings 
(or their equivalent) is divided into sections by means of 
metallic stops or plugs substantially as described. 

13. Eeceivers substantially as described and shown in figures 
5 and 8. 

14. Transmitters substantially as described and shown at 
figures 6 and 7. 

15. A receiver consisting of a sensitive tube or other imper- 
fect contact inserted in a circuit, one end of the sensitive tube 
or other imperfect contact being put to earth whilst the other 
end is connected to an insulated conductor. 

16. The combination of a transmitter having one end of its 
sparking appliance or poles connected to earth, and the other 
to an insulated conductor, with a receiver as is mentioned in 
claim 15. 

17. A receiver consisting of a sensitive tube or other imper- 
fect contact inserted in a circuit, and earth connections to each 
end of the sensitive contact or tube through condensers or their 

18. The modifications in the transmitters and receivers, in 
which the suspended plates are replaced by cylinders or the 
like placed hat-wise on poles, or by balloons or kites substan- 
tially as described. 

19. An induction coil having a revolving make and break 
substantially as and for the purposes described. 

Dated this 2nd day of March 1897. 



Aerial telegraph, an, 73 et seq. 

Andres, Signer Senlicq d', 8 fn. 

Armstrong, Lord, 270 fn. 

Ascoli, Prof., 215. 

Atlantic telegraph, an, Lind- 
say's proposals, 21 et seq. 
a telegraph without a cable, 

Auticatelephor of Edwards, 8 
et seq. 

Barclay, A., 78. 

Bell, Prof. Graham, his photo- 
phone, 5 and f n. experi- 
ments in communicating be- 
tween ships at sea, 96 et seq. 
251, 252. 

Beron's ' M^te"orologie Simpli- 
fied ' referred to, 66 fn. 

Blake, Prof. Lucien, experiment 
showing sensitiveness of the 
telephone, 85130 fn. 

Blissett, Mr, 114. 

Blondel, Prof., 232 fn. 

Bonelli, 29 fn., 104. 

Bouchotte, 29 fn. 

Bourbouze, M., 71 et seq. 

Boze, Prof. Chunder, 188. 

Branly, Prof. E., 189 et seq., 
195 et seq. on variations of 
conductivity, 276 et seq. 291. 

Brett, 104. 

Bright, Mr C., 130 fn. 

Brooke, Sir William O'Shaugh- 
nessy, experiments in sub- 
aqueous telegraphy, 39. 

Brown, Mr A. C., the inventor 
of the photophone, 5 fn. 
induction in train signalling, 
104 et seq. 176 fn. 

Call apparatus on the Fastnet 
rock, 173. 

Calzecchi-Onesti, Prof., 194 et 

Carty, Mr, on the electro-static 
phenomena on telephone cir- 
cuits, 144 fn. 

Charming, Dr, experiments 
showing sensitiveness of the 
telephone, 81 et seq. 

Churchill, Lord A. S., 78. 

Clark, Edwin, 104. 

Coherer. See Detector. 

Coils, communication between 
ships, &c., by, 122 et seq., 

Conduction methods of com- 
munication, 130 et seq., 162 
et seq. variations of con- 
ductivity under electrical in- 
fluence, 276 et seq. 

Cooke, William Fothergill, his 
system of train signals, 104. 



Crookes, Sir William, 197, 289. 

Davy, Edward, 6 et seq. plans 
for telegraphing without 
wires, ib. proposal for com- 
munication with trains in 
motion, 103. 

Bering, G. E., his needle teleg- 
raphy, 48 methods of carry- 
ing off atmospheric electricity 
from the line- wires, ib. pro- 
posals for a transmarine tele- 
graph, 49 et, seq. attempt to 
apply his system, 53 et seq. 

Detector, Wilkins's, 36 et seq. 
Lord Kelvin's and other re- 
lays, 37 et seq. Highton's 
42 et seq. Hertz's, 182, 
1 90 Right's, ib. Lodge's 
" coherer," ib. Branly's 
radio - conductor, ib., 196 
- Mr Rutherford's detec- 
tor, 200 Rev. F. Jervis- 
Smith's, 202 Marconi's, 204 
et seq.. Lodge's form of the 
Branly coherer, 231 et seq. 

Dietz, Dr, 216. 

Dolbear, Prof. A. E., his system 
of wireless telegraphy, 99 et 

Dolbear, Mr C., 103 fn. 

Douat, 29 fn. 

Dufour, M. Henri, experiment 
in inductive effect in tele- 
phone circuit, 84. 

Dujardin, 104. 

"Earth as Part of a Voltaic 
Circuit, the," extract from 
'The Electrician' on, 66 
et seq. 

Earth, Salva's suggestion to 
electrify, 2 the earth bat- 
tery, 20 Steinheil's dis- 
covery of the earth circuit, 
3 earth- currents or leak- 
ages, 141 et seq. 

Edison, Mr T. A., his system 
of train signals, 107 et seq. 

Edser, Prof., 180. 

Edwards, Mr T. W. C., the 
Auticatelephor of, 8 et seq. 

Electric currents, nature of, 
264 et seq. electric waves 
and their application to wire- 
less telegraphy, 289 et seq. 

Electrical oscillations, 179 et 
seq. radiation, 186. 

Evershed, Mr Sydney, plan for 
communicating with light- 
ships, 128 fn. his relays, 

Exciter, Hertz's, 182, 189 
Sarasin and de la Rive's, ib. 
Righi's, ib. Marconi's, 
203 et seq. 

Fahie, J. J., reference to 'His- 
tory of Electric Telegraphy 
to 1837 'by, 1, 3 fn., 20 fn., 
104 fn. 

Faraday, Michael, 249. 

Feddersen, 179. 

Fitzgerald, Mr, of Dublin, 249, 

Fleming, Prof., on Marconi's 
system, 241 et seq. 

Galvanometer. See Detector. 

Gauss, 3. 

Gavey, Mr, 146, 161. 

Gilliland, E. T., 107 et seq. 

Gintl, 29 fn. 

Glanville, Mr, 221. 

Gott, Mr J. , use of the telephone 

in wireless telegraphy, 85 et 

Granier, Mr, proposal of an 

aerial line, 71. 
Granville, W. P., 166. 
Grove, Sir W. R., 251. 

Hamel, Dr, account of Salva's 
experiment, 2. 



Haworth, John, unintelligibility 
of his proposals, 55 et seq. 
summary of his specification, 
58 et seq. Mr Varley's cor- 
respondence with, 61 et seq. 
Mr Haworth's reply, 65. 

Heaviside, Mr A. W., 145, 

Helmholtz, 179. 

Henry, Prof. Joseph, experi- 
ments in induction, 93 et seq. 
185 fn. on high tension 
electricity, 261 et seq. 295. 

Hertz, Prof. Heinrich, 177 et 
seq., 267 et seq. 

Highton, Edward and Henry, 
experiments in transaqueous 
telegraphy, 40 et seq. 

Hippisley, Capt., R.E., 139 fn. 

Hughes, Prof. D. E., 199 fn. 
on electric waves, 289 et 

India, subaqueous telegraphy in, 
39, 114 et seq. 

Induction, employment in wire- 
less telegraphy of, 92 et seq. 
electro-static currents, 142 
etseq. electro-magnetic cur- 
rents, 144 et seq. com- 
munication by means of in- 
duction, 157 et seq. 

Insulation, telegraphing with- 
out, 21 et seq., 39 et seq., 49, 
53, 115 et seq., 176 fn. 

Jackson, Capt., R.N., 202. 

Jervis-Smith, Rev. F., 202. 

Johnston, Mr W. P., arrange- 
ment for signalling across a 
canal, 114 et seq. 

Kelvin, Lord, 179, 220, 256, 

270 fn. 

Kerr, Dr, of Glasgow, 251. 
Kerr's ' Wireless Telegraphy ' 

referred to, 28 fn. 

Langdon-Davies, Mr, his phono- 
phore, 236. 

Lighthouses, telegraphic com- 
munication with, 164 et seq. 

Lightning, effect of, on tele- 
phone, 80. 

Lightships, communication with, 
Evershed's plan, 128 fn. 
by Marconi's system, 224 et 

Lindsay, James Bowman, out- 
line of his life, 13 et seq. 
experiments in electric light- 
ing, 18 et seq. proposals for 
telegraph to America, 20 et 
seq. experiments without 
wires, 24 et seq. Mr Preece's 
recollection of, 28. 

Little, 104. 

Lodge, Prof. Oliver, 95 fn. on 
the law of distance, 127 fn. 
his conception of electricity, 
140 fn. 175, 189, 190, 196, 
197 fn., 200, 227, 291 on 
the relation between electric- 
ity and light, 246 et seq., 271 
et seq. 

Loomis, Mahlon, 73 et seq. 

Marconi, Guglielmo, 197 et seq., 
295 reprint of his specifi- 
cation, 296 et seq. 

Maxwell, James Clerk-, 178, 
186, 249, 254, 257, 264 et 

Melhuish, Mr W. F., experi- 
ments in signalling across 
rivers in India, 116 et seq. 

Minchin, Prof., 190, 200, 252. 

Molesworth, J., 78. 

Morse, Prof., 10 et seq. experi- 
ments in telegraphing through 
water without wires, 11 et 

Mower, J. H., 70 et seq. 

Muirhead, Dr Alexander, 233. 

Munro, Mr John, 296 fn. 



Nelson, Henry, of Galesburg, 

87 fn. 

Newton, A. V., 78. 
Newton, W. K, 78. 
Nickels, B., 78. 
Norrie's * Dundee Celebrities of 

the Nineteenth Century' 

quoted, 18 fn. 

O'Shaughnessy, Dr. See Brooke, 
Sir William O'Shaughnessy. 

Page's discovery of galvanic 
music, 94 fn. 

Pasqualini, Mr, 227 fn. 

Photophone, Steinheil's proposal, 
5 the true inventor of the, 
ib. fn. 

Pierce, Prof., experiments show- 
ing sensitiveness of the tele- 
phone, 79. 

Popoff, Prof., 200 et seq. 

Poynting's theory concerning 
electric current, 185. 

Preece, W. H., papers by, 136 
et seq. disturbances on tele- 
phone lines, 137 et seq. 
experiment in telegraphing 
across the Solent without 
wires, 138 et seq. definition 
of electricity, 140 resume 
of his experiments, 141 et 
seq. 194 fn., 202, 206, 211, 

Radio-conductor. See Detector. 

Railway: use of rails as con- 
ductors, 3 railway tele- 
graphs, 103 et seq. 

Rathbone, Mr Charles, experi- 
ments showing sensitiveness 
of telephone, 80. 

Rathenau, Prof. Erich, experi- 
ment on the conductive prin- 
ciple, 130 et seq. 

Relay, Wilkins's, 38. 

Righi, Prof., 189, 190. 

Rive, L. de la, explanation of 

"Galvanic Music," 94 fn. 

184, 189. 
Rosser, H. S., 78. 
Rovelli, Signer, 202 fn. 
Rowland, Prof. H. A., on the 

nature of electric currents, 

264 et seq. 
Rupp, Dr, 196 fn. 
Rutherford, 200. 

Sacher, Prof. E., inductive ef- 
fect in telephone circuits, 

Salva, suggestion to use the sea 
as a conductor, 1 87. 

Sarasin, E., 184, 189. 

Schafer, Mr Bela, 227 fn. 

Schilling, Baron, the needle 
telegraph of, 20. 

Schuster, Arthur, 292 fn. 

Schwendler, Mr, 114. 

Sennett, Mr A. R., 8 fn. 

Shaffner's ' Telegraph Manual ' 
referred to, 234. 

Ships, plans for intercom- 
munication between, at sea, 
90 et seq., 96. et seq., 102, 
122 et seq. 

Siemens' Serrated-Plate Light- 
ning-Guard, 48. 

Slaby, Prof., 212, 215 et seq. 

Smith, Mr Willoughby, on 
" Volta-Electric Induction," 
94 fn. induction in train 
signalling, 105 et seq. his 
system of wireless teleg- 
raphy, 162 et seq. 

Sommerring, experiment in sig- 
nalling through water, 2. 

Steinheil, Prof. C. A., 3 et 
seq. experiments with rail- 
way rails as conductors, ib. 
discovery of the earth circuit, 
ib. signalling without wires, 
4 et seq. suggestion of the 
photophone, 5 89. 



Stevenson, Mr C. A., his coil 
system, 122 et seq. 

Stokes, Sir George, 292 fn., 

Strong, Mr H. C., of Chicago, 
87 fn. 

Sturgeon's ' Annals of Elec- 
tricity' quoted, 4, 5. 

Sympathetic needle and sym- 
pathetic flesh telegraphs, 1. 

Taylor, Capt., R.K, the com- 
pressed air telephone of, 7. 

Telephone in relation to wire- 
less telegraphy, 79 et seq. 

Tesla, Prof. Nikola, his con- 
ception of electricity, 140 
fn. 199 et seq. 

Thompson, Prof. Silvanus, 206, 

Thomson, Sir W. See Kelvin, 

Threlfall, Prof. R., 197 fn. 

Trains, electric communication 
with moving, 103 et seq. 

Trowbridge, Prof. John, 32 et 
seq. experiments with the 
telephone, 87 et seq. an 
Atlantic telegraph without 
a cable, 90 communication 
between ships at sea, ib. et 
seq. induction in wireless 
telegraphy, 92 et seq. 

Tuma, Dr, 219 fn. 

Vail's * American Electro-Mag- 
netic Telegraph' quoted, 13. 
Van Reese, 29 fn. 
Varley, Mr S. A., 191. 

Walker, T., 78. 

Welding by electricity, 23. 

Wilde, H., 78. 

Wilkins, J. W., 32 et seq. 
proposal for telegraph com- 
munication without wires, 
33 et seq. the Wilkins re- 
lay, 36 et seq. 

Zickler, Prof. K., 183 fn. 





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