CHAPTER V.

TESTIMONY OF CONTEMPORARY WITNESSES.

1. Professor G. Quincke. 2. Professor C. Bohn. 3. Herr Léon Garnier. 4. Ernest Horkheimer, Esq. 5. Dr. R. Messel, F.C.S. 6. Herr Heinrich Holt. 7. Herr Heinrich F. Peter. 8. Mr. Stephen M. Yeates. 9. Dr. William Frazer.

Professor G. Quincke,

_Professor of Physics in the University of Heidelberg_.

[Professor Quincke, whose name is so well known in connection with his researches in molecular physics and in many problems of the highest interest to those acquainted with electrical science, was one of those present at the Naturforscher Versammlung held at Giessen in 1864, where Reis’s Telephone was publicly exhibited by its inventor, see page 93, _ante_. His testimony, coming from so high authority, is therefore of exceptional value.]

“Dear Sir,

“I was present at the Assembly of the German Naturalists’ Association (Naturforscher Versammlung) held in the year 1864 in Giessen, when Mr. Philipp Reis, at that time teacher in the Garnier Institute at Friedrichsdorf, near Frankfort-on-the-Main, showed and explained to the assembly the Telephone which he had invented.

“I witnessed the performance of the instruments, and, with the assistance of the late Professor Böttger, heard them for myself.

“The apparatus used consisted of two parts--a transmitter and a receiver. The transmitter was a box, one side of which was furnished with a tube into which the speaking was to be done. At the top or the side of the box there was a circular opening, covered by a tympanum of membrane, upon which was fastened a piece of platinum. This piece of platinum was in communication with one pole of the galvanic battery. Over the membrane, resting upon the platinum, and in contact with it, was a piece of metal furnished with a platinum point, also in connection with one pole of the battery.

“The receiver consisted of a common knitting needle of steel, surrounded by a magnetising coil of insulated wire, which also formed a part of the circuit, the whole resting on a resonant box.

“I listened at the latter part of the apparatus, and heard distinctly both singing and talking. I distinctly remember having heard the words of the German poem, ‘Ach! du lieber Augustin, Alles ist hin!’” &c.

“The members of the Association were astonished and delighted, and heartily congratulated Mr. Reis upon the success of his researches in Telephony.

(Signed) “Dr. G. Quincke, Professor.

“Heidelberg, 10th March, 1883.”

* * * * *

Professor C. Bohn.

[Professor C. Bohn, of Aschaffenburg, was formerly Secretary to the German “Naturforscher” Association, was also Secretary to the Physical Section of this Society (vide p. 93). In that capacity he had every opportunity of knowing what was going on in science; hence the following (translated) letter, addressed to the author of this book, is of peculiar value.]

“Most esteemed Sir,

“I willingly answer, as well as I am able to do so, the questions put by you. In order to explain that my recollections may not have all the sharpness that might be wished, I make the following prefatory statement. I have, about 1863, held numerous conferences with Mr. Reis and with my deceased colleague, Professor H. Buff, of Giessen, and on these occasions have argued the question how it is that the transmission of thoughts to a distance by the sensation of the ear has a distinctly less value than transmission by that which is written....

“And now to your questions. I was not at Stettin in 1863. At the experiments at Giessen in the Naturforscher Assembly on 21st September, 1864, I was present; the short notice about them in the journal (‘Tagesblatt’) is from my pen. I was Secretary of the Assembly and of the Physical Section. I remember, however, almost absolutely nothing about _these_ experiments. But I remember well that _previously_--therefore probably as early as 1863--having jointly made the experiments with Reis’s telephone in Buff’s house in Giessen.... I have _myself_, as speaker and as hearer, at least twice, in the presence of Reis, made the experiments.

“It was known to me (in 1863-64) that Reis intended to transmit words, and certainly spoken words as well as those sung. My interest in the matter was, however, a purely scientific one, not directed to the application as a means of profit.

“With great attention the sense of the words was understood. I have understood such myself, without knowing previously what would be the nature of the communication through the telephone. Words sung, especially well accentuated and peculiarly intoned, were somewhat better (or rather less incompletely) understood than those spoken in the ordinary manner. There was indeed a boy (son of Privy-Councillor Ihering, now of Göttingen, then of Giessen), who was known as specially accomplished as a speaker. He had a rather harsh North-German dialect, and after the first experiments hit on the right way to speak best, essential for understanding. I myself _did not_ understand Professor Buff through the telephone. Whether the speaker could be recognized by his voice I doubt. We knew beforehand each time who speaks. Yet I remember that a girl could be distinguished from that boy by the voice.

“The ear was at times laid upon the box of the apparatus, also upon the table which supported the telephone. Then it was attempted to hear at a distance, with the ear in the air; in this respect, when singing, with good result. At times the lid was taken off, or the same was connected more or less tightly or loosely with the lower part. The result of these changes I can no longer give with distinctness....

“Should you desire further information, I am ready to give you it according to my best knowledge.

“Hochachtungsvoll ergebenster, “Dr. C. Bohn.

“Aschaffenburg, “_10th September, 1882_.”

* * * * *

Léon Garnier.

[Herr Léon Garnier, Proprietor and Principal of the Garnier Institute at Friedrichsdorf, is the son of the late Burgomaster Garnier, who founded the establishment, and who, as previously narrated, encouraged Philipp Reis in his work and offered him the post of teacher of Natural Science. Herr Léon Garnier owns the small collection of instruments which Reis left behind, and which are preserved in the Physical Cabinet attached to the Institute, where also may be seen the gravitation machine--an ingenious combination of the principles of Atwood’s and Morin’s machines--and the automatic weather-recorder invented by Reis, both, however, very greatly out of repair. Herr Garnier has furnished to a friend the following particulars about Reis and his invention.]

“I knew Philipp Reis, now deceased, during his life-time.... About the year 1859, he was employed by my father, then proprietor and director of the Friedrichsdorf Garnier Institute, as teacher of mathematics and natural sciences. He employed his hours of leisure in experimenting for himself in a house occupied by himself, and in which he had established a physical laboratory with a view mainly of realizing an idea which he had conceived sometime before of transmitting the human voice over divers metallic conductors by means of a galvanic current.... I remember especially, that, standing at the end of the wire or conductor, Mr. Reis speaking through his instrument, I distinctly heard the words: ‘Guten Morgen, Herr Fischer’ (Good morning, Mr. Fischer); ‘Ich komme gleich’ (I am coming directly); ‘Passe auf!’ (Pay attention!); ‘Wie viel Uhr ist es?’ (What o’clock is it?); ‘Wie heisst du?’ (What’s your name?) We often spoke for an hour at a time. The distance was about 150 feet.

“Léon Garnier.”

* * * * *

Ernest Horkheimer, Esq. “Manchester, _Dec. 2, 1882_.

“Professor S. P. Thompson, “Dear Sir,

“In reply to your favour of 31st instant, I shall be very happy to give you all the information I can with respect to the telephonic experiments of my late friend and teacher Mr. Philipp Reis. I would express my gratification at finding that you are trying to put my old teacher’s claims on their just basis. I have always felt that in this race for telephonic fame, his claims have been very coolly put aside or ignored. That he did invent the Telephone there is not the remotest doubt. I was, I think, a great favourite of his; and at the time his assumption was that I was destined for a scientific career, either as a physicist or a chemist; and I believe that he said more to me about the telephone than to any one; and I assisted him in most of his experiments prior to the spring of 1862.

“Philipp Reis intended to transmit speech by his telephone--this was his chief aim; the transmitting of musical tones being only an after-thought, worked out for the convenience of public exhibition (which took place at the Physical Society at Frankfort-on-the-Main). I myself spent considerable time with him in transmitting words through the instruments. We never (in my time) got the length of transmitting complete sentences successfully, but certain words, such as ‘_Wer da?_’ ‘_gewiss_,’ ‘_warm_,’ ‘_kalt_,’ were undoubtedly transmitted without previous arrangement. I believe Reis made similar experiments with his brother-in-law.

“I recollect the instrument in the shape of the human ear very well: it was Reis’s earliest form of transmitter. The transmitter underwent a great many changes, even during my time. The form you sketch (Fig. 9, p. 20) was almost the oldest one, and was soon superseded by the funnel-shape (Fig. 35). The back was always closed by a tympanum of bladder, and many a hundred bladders were stretched, torn, and discarded during his experiments. I recollect him stating to me that he thought a very thin metal tympanum would eventually become the proper thing, and one was actually tried, coated over on one side with shellac, and on the other likewise, except at the point of contact (Fig. 36). I believe it was made of very thin brass, but at the time the experiments were not satisfactory. Talc was also tried, but without success, the platinum contacts being in all cases preserved.

“I remember very well indeed the receiver with a steel wire, surrounded by silk-covered copper wire. The first one was placed on an empty cigar-box, arranged thus:--

“The wire was a knitting-needle and the copper wire was spooled on a paper case.

“The spiral was supported by a little block of wood, so as to allow the knitting-needle not to touch it anywhere. Later on a smaller cigar-box was invented as a cover--thus; (Fig. 38)--having two holes cut into it like the _f_-holes in a violin.

“The practice was to place the ear close to the receiver, more particularly so when the transmission of words was attempted.

“The spiral was, during the early experiments, placed on a violin--in fact, a violin which I now possess was sometimes used, as it was of a peculiar shape, which Reis thought would help the power of tone.

“I have already enumerated some of the words which were transmitted, but there were many more; on one occasion a song, known in this country as ‘The Young Recruit’ (Wer will unter die Soldaten) was transmitted, the air and _many_ of the words being clearly intelligible.

“I do not recollect seeing the receiver shewn in the woodcut (Fig. 21), but Reis often said that he would make such a one, although the sketch he made for me then differed in some details from your woodcut. Reis intended to keep me fully informed of all he could achieve, but, immediately after leaving his tuition, I fell ill, and was laid up for a very long time. Shortly afterwards I left for England, and then he died, and I never saw him again. The electromagnet form was certainly strongly in his mind at the time we parted, and he drew many alternative suggestions on paper, which have probably been destroyed; but the electromagnets in all of them were placed upright, sometimes attached to the top of a hollow box, and sometimes to the bottom of a box arranged thus (Figs. 39, 40); but, to my recollection, they never got beyond the stage of drawings, whatever he may have done after he and I parted company.

“In conclusion, I beg to send you herewith a photograph of Philipp Reis (see Fig. 12, p. 23), holding in his hand the instrument I helped him to make, and which photograph he took of himself, exposing the camera by a pneumatic arrangement of his own, and which formed part of a little machine which he concocted for turning over the leaves of music-books.

“The instrument used by Reis at the Physical Society may have been the square block form: I believe that this cone-form was not quite completed then. At the Saalbau (Hochstift), however, I am _sure_ the instrument shown in my photograph was employed; not with a tin cone, but a wooden one. I send you herewith a sketch of what I remember that instrument to have been. I am not absolutely certain whether in the instrument there was not an electromagnet introduced, but I think not. My recollection leads me to suppose that the electromagnet arrangement was added subsequently. Thinking it over again, I should, however, think that the instrument in the photo must have been one in which a bent lever was placed behind the tympanum, and that the rectangular patch seen above was a wooden casing to shelter the parts. There may be some confusion in my mind as to the position of this box, but I somehow think the rectangular patch is only part of a larger box which is not apparent in the photograph. I have no idea where the original instrument is now, but I should hardly think it could be in existence. Reis used to take some instruments to pieces to utilise parts in subsequent experiments, and I recollect how keen he used to be about the bits of platinum, which he always described as ‘ein sehr kostbares Metall.’ What always was a great puzzle was the attaching of the platinum plate to the membrane, which he did generally by sealing-wax, saying at the same time: ‘Es ist nicht recht so, aber ich weiss nicht wie es anders gemacht werden kann!’

“Believe me, my dear Sir, yours truly, “Ernest Horkheimer.”

* * * * *

Dr. Rudolph Messel.

[The following letter from Dr. Rudolph Messel, F.C.S., addressed to the author of this book, in reply to enquiries concerning Reis and his inventions, speaks for itself. Dr. Messel’s letter differs from almost all the others here reprinted in having been specially written for the purpose of being inserted in this volume.--S. P. T.]

“36, Mark Lane, London, _30th April, 1883_. “Dear Professor Thompson,

“At last I find a moment to comply with your request. My knowledge of Philipp Reis dates from 1860, when I was a pupil at Professor Garnier’s School at Friedrichsdorf, of which school Reis was one of the undermasters. Reis, naturally communicative, was very fond of talking to us boys about his scientific researches. And it was on the occasion of one of our daily walks together that he told me how, when an apprentice at Beyerbach’s (colour-manufacturer), in Frankfurt-a.-M., he was one day amusing himself in watching the behaviour of a small magnetic compass. This compass he found, on being placed near to the base of various iron columns in the warehouse, was attracted. Disturbed by the entrance of one of the principals, who imagined that Reis ought to employ his time more profitably, he withdrew to a stage where he could pursue his experiments unobserved. Much to his surprise, he now found that the pole attracted by the base was repulsed at the top of the columns, which observation led him to examine other pieces of iron on the premises. He next built up a column with all the weights in the warehouse, and having verified his previous observations, he communicated what he believed to be his first and great discovery either to Professor Böttger or to Dr. Oppel. Great was his disappointment to learn at this interview that he had unwittingly stumbled across a well-known physical fact: but his disappointment stimulated in him the desire to learn more of the marvellous laws and mysteries of nature. That Reis evoked a similar desire in those with whom he came in contact need not cause surprise, and thus it came about that Horkheimer, Küster, Schmidt, and myself, soon enjoyed the privilege of private instructions in physics, and of being permitted to witness his telephonic experiments amongst others. I was, however, very young, and am sorry that much that I then saw and heard has been forgotten, Reis insisted that his transmitter (which he called the ‘ear’) should be capable of performing the functions of that organ, and he never tired of drawing diagrams of the numerous curves of sounds to explain how necessary it was that the transmitter should follow these curves before perfect speaking could be attained, and which kind of curves the instrument so far could reproduce. Numerous experiments were made with transmitters, exaggerating or diminishing the various component parts of the ear. Wooden and metallic apparatus, rough and smooth, were constructed in order to find out what was essential, and what was not.

“One form of transmitter was at that time constructed which I miss amongst the various woodcuts you were good enough to send me, and one which Reis based great hopes upon. The instrument was very rough, however, consisting of a wooden bung of a beer-barrel (which I had hollowed out for an earlier telephone--it was not turned inside like others), and this was closed with a membrane. The favourite ‘Hämmerchen’ was replaced by a straight wire, fixed in the usual way with sealing-wax, and the apparatus stood within a sort of tripod, membrane downwards, the pin just touching the surface of a drop of mercury contained in a small cup forming one of the terminals of the circuit. The apparatus started off with splendid results, but may probably have been abandoned on account of its great uncertainty, thus sharing the fate of other of his earlier instruments. In my belief it is to these mechanical imperfections, due principally to the want of sufficient means at his command, that we must look to find the reason why Reis’s telephone did not come to an earlier fame. Thus Reis informed me that he intended to exhibit it once at some scientific meeting at Cassel, but notwithstanding a perfect rehearsal it was impossible to show the working to the audience; the failure was attributed by Reis to atmospheric influence (stretching of the diaphragm), and he felt much grieved at having lost his chance. To make matters worse, the early transmitters had no adjusting screws, and the contact was only regulated by a piece of bent wire, and the ‘hammer’ was fixed to the membrane. Philipp Schmidt should recollect what I state, as many experiments were made when only he, Reis, and myself were present, he being at one and I at the other end of the apparatus. The wire was stretched from Reis’s house, in the main road, through the yard to a hayloft, near the garden or field. We transmitted musical sounds (organ, &c.), singing popular songs (‘Wer will unter die Soldaten,’ ‘Ich hatt’ einen Kameraden,’ &c.) and speaking, or, more correctly, reading. We had a book, and were to find out what part of the page the reader was just transmitting. We frequently used a sort of ‘Exercier Reglement,’ a soldiers’ instruction book, or something of that sort. I have a distinct recollection of electromagnetic receivers being used, but not of their construction, except that the use of one of them was accompanied by a rattling and disturbing noise. The knitting-needle put in the _f_ of a violin was, however, the more favoured receiver, but at this time, in Reis’s mind, all seemed to hinge on the electromagnet, as it had before, and, I dare say, did again afterwards on the transmitter. I left Friedrichsdorf in ’62, and rarely saw Reis after that, except a few times at Mechanicus Albert’s (who made some of his apparatus), and at Professor Böttger’s, to whom he introduced me. Reis attended Professor Böttger’s lectures at the Physikalischer Verein, when in Frankfort, prior to his settling down at Friedrichsdorf; but I do not know that any particularly intimate relation existed between them. Dr. Poppe, director of the Gewerbeschule (Trade School), now deceased, on whose advice he chiefly relied, was then one of his more intimate friends, Professor Oppel being occasionally consulted about more intricate mathematical problems. Of the ‘meteorological recorder’ invented by Reis I recollect but its existence, but nothing at all of a ‘fall-machine’ of his construction. The velocipede I only recollect, because he lent it to me for a masquerade. At his suggestion we altered it into a large musical-box, putting Herr Peter inside, who played on the clarinet when I turned a handle. Dr. Kellner states that its chief merit consisted in being able to go downhill, and that poor Reis came back (uphill) puffing away, dragging his velocipede behind him. Kellner no doubt could give valuable information on Reis’s theory of electricity, his conviction that there was only one kind of electricity, his acoustic researches, and those on radiation of electricity, his galvanoplastic experiments, &c., &c.

“In personal appearance Reis was not very refined, but he had a striking countenance and a very powerful look. Though occasionally very irritable, especially with dunces, he was always warm-hearted, and showed great kindness to those who cared to understand him. Reis’s views of the telephone may, of course, have changed after I knew him, and looking at his later instruments, one of which I possess, I cannot help thinking they did; at any rate, I do not see how, in these instruments, the current got interrupted at all, and the instruments must have acted like microphones, whether known or unknown to him. When listening to the instrument he frequently said to me, “You understand it is a ‘molekular Bewegung’ (molecular motion).

“I am sorry that, owing to the lapse of time, I am unable to throw more light on Reis’s original labours in a field of physical science which promised so much for the future; but insufficient as are my recollections, they may not be without public interest, and at any rate I am glad of this opportunity of offering my humble tribute of regard and affection to the memory of my old teacher and friend.

“Yours truly, “Rudolph Messel.”

* * * * *

Heinrich Hold.

[Herr Hold, formerly a colleague of Philipp Reis in the Garnier Institute at Friedrichsdorf, but now proprietor of a leather factory in the same place, was teacher of mathematics. He was in his younger days a fellow-student of Professor Tyndall at Halle, and was well acquainted with physical science in general. His intimate connection with Reis, and close knowledge of Reis’s work, enable him to confirm the testimony of others in many important points.]

To Professor S. P. Thompson in Bristol.

“Esteemed Sir,

“I have much pleasure in furnishing you with the following particulars concerning my late colleague Philipp Reis, the inventor of the Telephone. He was himself educated at the Garnier’s Institute in Friedrichsdorf where I was also teacher of mathematics. I knew him very well during his life-time. Among his numerous original researches, his invention of the telephone was the principal one. His idea was to reproduce the tones both of musical instruments and of the human voice by means of electricity, using a covered wire wound in a spiral round an iron core, the same being placed upon a resonant box. In this he succeeded, inasmuch as with an apparatus, which he showed to the Physikalischer Verein in Frankfurt-a.-M., in the year 1861, he reproduced music, singing, single words and short sentences; all of which were distinctly audible over a short distance from his dwelling-house through the yard to the barn. Every voice was not equally well adapted for speaking into the apparatus, neither could every ear understand the telephone language equally well. Words spoken slowly, and singing, both in a middle tone, were the most easy to reproduce. I helped Mr. Reis to make many of his experiments, and have spoken and sung into the telephone, the same being generally heard and understood. I have also heard and understood short sentences when I was standing at the end station. A brother-in-law of Mr. Reis, who is now paymaster in the Imperial Navy at Wilhelmshavn, generally conducted the speaking and singing in the telephone.

“Heinrich Hold.”

* * * * *

Heinrich Friedrich Peter.

[Herr Peter is still Music-teacher in the Garnier Institute, and has a vivid recollection of his former colleague Philipp Reis, and of the experiments with the telephone.]

“Dear Sir,

“The following particulars concerning Reis’s Telephone I have several times narrated. I was teacher of music in Garnier’s Institute at the time when Mr. Reis invented the telephone, in the year 1861. I was much interested in his experiments, and visited him daily, giving him help and making suggestions. His first idea was to imitate the construction of the human ear. He constructed a funnel-shaped instrument, the back of which was covered with a skin of isinglass, upon which was fastened a piece of platinum, against which rested a platinum point. As receiver of the electric current he used a common knitting-needle, surrounded by a coil of insulated green wire, which was at first merely laid on a table. At first the tones were very much interfered with by a buzzing noise. At my suggestion he placed the spiral upon my violin as a resonant-box; whereupon the tones were perfectly understood, though still accompanied by the buzzing noise. He continued experimenting, trying various kinds of membranes, and made continual improvements in the apparatus. I was present and assisted at the experiments at Frankfort-on-the-Main, on the 26th of October, 1861; and after the meeting broke-up, I saw the members of the Society as they came and congratulated Mr. Reis on the success of his experiments. I played upon the English horn, and Philipp Schmidt sang. The singing was heard much better than the playing. At an experiment which we made at Friedrichsdorf, in the presence of Hofrath Dr. Müller, Apothecary Müller, and Professor Dr. Schenk, formerly Director of Garnier’s Institute, an incident occurred which will interest you. Singing was at first tried; and afterwards his brother-in-law, Philipp Schmidt, read long sentences from Spiess’s ‘Turnbuch’ (Book of Gymnastics), which sentences Philipp Reis, who was listening, understood perfectly, and repeated to us. I said to him, ‘Philipp, you know that whole book by heart;’ and I was unwilling to believe that his experiment could be so successful unless he would repeat for me the sentences which I would give him. So I then went up into the room where stood the telephone, and purposely uttered some nonsensical sentences, for instance: ‘Die Sonne ist von Kupfer’ (The sun is made of copper), which Reis understood as, ‘Die Sonne ist von Zucker’ (The sun is made of sugar); ‘Das Pferd frisst keinen Gurkensalat’ (The horse eats no cucumber-salad); which Reis understood as ‘Das Pferd frisst....’ (The horse eats ...). This was the last of these experiments which we tried. Those who were present were very greatly astonished, and were convinced that Reis’s invention had opened out a great future.

“H. F. Peter, Musiklehrer.”

* * * * *

Stephen Mitchell Yeates, Esq.

[Mr. Yeates is a well-known instrument-maker in the city of Dublin, and in 1865, purchased from Mr. W. Ladd, of London, a Reis’s Telephone of the form shown in Reis’s Prospectus (Fig. 29). Mr. Yeates, after a few experiments, rejected the knitting-kneedle receiver, and replaced it by the instrument shown in Fig. 42, which consisted of an electromagnet mounted above a sound-box, having a vibrating armature furnished with an adjusting screw to regulate its distance from the poles of the electromagnet. This instrument worked, even when the armature was in absolute contact with both poles of the electromagnet, and as the magnet did not during the experiments lose its hold on the armature, it was clear that the effects were due to alterations in the intensity of the magnetism of the magnet. The apparatus was shewn at the November meeting of the Dublin Philosophical Society, when singing and words were transmitted. With a careful adjustment it was possible to distinguish all the quality of the note sung into the transmitter and to distinguish the difference between any two voices. The instruments were then sold to the late Rev. Mr. Kernan, who was then Professor of Physics in Clongowes Wood College. The following recent letter from Mr. Yeates corroborates the above facts.]

“2, Grafton Street, Dublin, “_March 1st_, 1883.

“Dear Sir,

“There are several residing at present in Dublin who were present at my telephonic experiments in 1865; three of them, namely, Dr. W. Frazer, Mr. A. M. Vereker, and Mr. E. C. Tuke, took an active part in the experiments, and remember all the circumstances connected with them. The voice of each was instantly recognised in the receiver; in fact, this point attracted special attention at the time.

“I had no knowledge at that time that Reis had used an electromagnetic receiver, nor did I know that Reis was the inventor of the instrument which I got from Mr. Ladd.

“The original instrument made by me is, I believe, still in the Museum at Clongowes Wood College. The President kindly lent it to me some time ago, and I returned it to him again after showing it to Professor Barrett. I have a cut of this receiver, which I will send to you if it will be of any use to you.

“Yours truly, “S. M. Yeates.”

* * * * *

William Frazer, Esq., M. D.,

“20, Harcourt Street, Dublin, “_March 13_, 1883.

“Dear Sir,

“I have a distinct recollection of the Telephone. We had a small private club meeting once each month for scientific purposes. On referring to my note-books, I find that there was a meeting on Thursday evening, October 5th, 1865. It was held in Nassau Street, at the residence Mr. Horatio Yeates, now in Australia, and brother of Mr. Stephen Yeates. The Telephone was upstairs, in the third story of the house, and the voice heard in the hall. Mr. Vereker, of the Bank of Ireland, Mr. John Rigby, of rifle celebrity, the two Mr. Yeates, and, I think, Mr. Tuke, were present with myself. There were some others, whom I cannot now recollect, but our club was small.

“Rigby sang ‘Patrick’s Day’ and ‘God save the Queen,’ and various questions were asked and answered. The separate words were most distinct, the singing less so; but there was no difficulty in recognising the individual who spoke by his voice.

“Being much interested in the subject, I got Mr. Yeates to allow the apparatus to be shewn at a Conversazione (Presbyterian Young Men’s) at the Rotunda on October 12, at 8 P.M. His assistant, Mr. Tuke, took charge of it that night. It was placed in a side room off the main round room of the buildings.

“I exhibited at the October 5th meeting of our club a specimen termed ‘Locust gum,’ probably derived from some _Robinia_, but really can tell you nothing more about it. There is merely a brief note of it in my private memoranda.

“Yours, dear Sir,

Believe me very truly,

“William Frazer,

“Fellow and Examiner, Royal College of Surgeons, “Ireland, Member of Council, Royal Irish “Academy, &c.”

“Silvanus P. Thompson, Esq., University College, Bristol.”

APPENDIX I.

COMPARISON OF REIS’S TRANSMITTERS WITH RECENT INSTRUMENTS.

Any one who compares together the many different forms of Reis’s Transmitters cannot fail to notice that amidst the great variety of form, two essential points are preserved throughout, the presence of which is fundamental. These two essentials are, firstly, the tympanum to collect the voice-waves, and, secondly, an electric mechanism, consisting of two or more parts in loose or imperfect contact with each other, and so arranged in combination with the tympanum that the motions of the latter should alter the degree of contact, and consequently interrupt, to a greater or less degree, the current of electricity flowing between the contact-pieces. It was of course familiar to all electricians, long before Reis, that a bad, or imperfect, or loose contact in a circuit offered a resistance and interrupted the flow of an electric current. In all ordinary telegraphic and electric apparatus great care was taken to avoid loose and imperfect contacts by using clamping-screws and solid connectors. But Reis, having made up his mind (see p. 77) that the action due to the magnetising current must vary in a manner corresponding with, and therefore proportional to, the vibrations of the voice, utilised this property of imperfect contacts which alter their resistance according to the degree of contact, by arranging his mechanism so as to apply the voice to vary the degree of contact. This was the essence of his transmitters. In other words, he applied the voice to control or moderate the strength of the current generated by a battery. His “interruptors” may therefore with propriety be called “electric current contact regulators;” and put into technical language, the essence of this part of his invention lay in the combination with a tympanum of electric current regulators working upon the principle of variable contact.

In another appendix is discussed the precise nature of that which occurs at a point of variable or imperfect contact, and which results in a corresponding change of electrical resistance when the degree of contact is varied. Suffice it to say here that it is impossible to vary the degree of contact between two bodies which are lightly pressing one against the other, and through which an electric current is flowing, without altering the resistance offered to the current by this joint in the circuit. If the two surfaces are pressed together, so that there is a good contact, the current flows more freely, finding less resistance. If, on the other hand, by altering the pressure or the amount of surface exposed, we change the degree of contact and cause fewer atoms of one piece to touch those of the other piece, the current meets with greater obstruction and cannot flow with such strength as before: it is partially “interrupted,” to use the expressive term employed by Reis.

Now this operation of varying the degree of pressure in order to vary the resistance of the interrupter or contact regulator, was distinctly contemplated by Reis. We find his definite instructions, for example (see p. 75), for arranging the relative lengths of the two parts of the curved lever in one of his transmitters, so that the movement of one contact-piece may act on the other contact-piece with the greatest possible _force_; in other words, he shortened his lever at the working end, sacrificing its range of motion in order to get a greater range of pressure at the contact-point.

It has often been said, but incorrectly, that Reis intended his “interruptors” or contact regulators to make and break the electric circuit abruptly in the manner of a telegraphic key worked by hand. No doubt in the mouth of a professional telegraph operator the words “interrupting” the circuit, and “opening” and “closing” the circuit, do now-a-days receive this narrow technical meaning. But Reis was not a professional telegraph operator: he did not (see p. 87) even know the signals of the Morse code, and it is self-evident that he did not use the terms in any such restricted or unnatural sense as abrupt “make-and-break,” because he proposed at the outset to interrupt the current in a manner represented by the gradual rise and fall of a _curve_, stating emphatically in his very first memoir on telephony (p. 55), that to reproduce any tone or combination of tones all that was necessary was “to set up vibrations whose curves are like those” of the given tone or combination of tones. Moreover, in the construction of almost all his transmitters, even in the very first--the model of the human ear--he purposely introduced certain parts which could have no other effect than to prevent the occurrence of complete breaks in the continuity of the current. In fact, instead of using rigid supports for his interruptor, he mounted one or both of the contact-parts with springs, so that one should follow the movement of the other with a gentle pressure never amounting to absolute break, except perhaps in the accidental case of a too loud shout. By employing these following-springs, he introduced, in fact the element of _elasticity_ into his interruptor; and clearly he introduced it for the very purpose of avoiding abrupt breaking of the contact. In the first form Fig. 5, p. 16 (the “ear”), there was one spring; in the fourth form, Figs. 9 and 10, p. 21 (the “bored block”), there were two springs, one of steel, curved, and one, a straight but springy strip, of copper; in the eighth form (the “lever” form), Fig. 14, p. 25, there were two springs; in the ninth form, Fig. 15, p. 26, there was a springy strip of brass. In the final form, Figs. 17 and 18, p. 27 (the “square-box” pattern), there was, it is true, a springy strip of copper, but the light adjustment of contact was in this form obtained, not by a spring, but by the inertia of the upper contact-piece which by its own weight pressed gently upon the lower contact-piece. In every one of these forms, except the last, there was moreover an adjusting-screw to determine the exact degree of initial pressure between the contact surfaces. Doubtless the difficulty of adjusting this screw to give the exact degree of contact, enhanced as that difficulty was in consequence of the liability of the membraneous tympanum to become flaccid by the moisture of the breath, induced Reis to think that the later form of the apparatus in which this adjustment was no longer retained would be more easy to use, or, as he says in his Prospectus, more accessible to others. Yet undoubtedly the absence of the spring at the contacts led some persons to fancy that the instrument was intended to be shouted or sung to so loudly that every vibration should make the upper contact-piece jump up from the lower, and as Professor Müller even suggests (p. 98), produce a spark! But such a manner of using the instrument would entirely defeat Reis’s most fundamental principle, that the interruptions should be such as to correspond to the _undulating curve_ which represents the pressure due to vibration of the sound-wave; the possibility of representing the degree of pressure by a curve being one of the two principles set forth in his paper “on Telephony” (p. 55), in which he remarks, that “Taking my stand on the preceding principles, I have succeeded in constructing an apparatus by means of which I am in a position to reproduce ... even to a certain degree the human voice.” Reis was perfectly well aware, as his curves show, that a complicated sound-wave does not consist invariably of _one_ condensation followed by _one_ rarefaction, but that there are all sorts of degrees of condensation which may follow one another, and all capable of being represented by a curve. If all sounds consisted of one rarefaction following immediately after each one condensation there might be some propriety in proposing that after each “make” of contact there should be a “break” in the sense of an abrupt or complete breach in the continuity of the current. But, obviously, the fact that one condensation may follow another without a rarefaction between (which Reis’s curves show that he knew) must be amply sufficient to prove that on Reis’s own principle _his interruptor was meant to produce variations in the degree of contact in exact correspondence with the variations in the degree of pressure_, whatever these might be. Had he not meant this, he could not have talked about “taking his stand” on the principle of representing varying pressures by an undulatory curve. Now, from what has been adduced, the following points are clear:--

_Firstly_, that the contact-regulator which Reis combined with the tympanum was meant to interrupt the current, more or less, according to the varying movements imparted to it by the voice.

_Secondly_, that Reis intended such interruptions or variations of contact to be proportional to, or to “correspond” with, the variations indicated by the undulatory curve of varying pressures.

_Thirdly_, that for the purpose of preventing the occurrence of abrupt breaks in the continuity of the circuit, he used springs and adjusting screws, and in one form availed himself of the inertia of the moving parts to attain a similar end.

It is also clear from his own prospectus, that he was aware that for the simpler and ruder purpose of transmitting musical airs, in which the number of the vibrations is the only consideration and where each single condensation is actually followed by a rarefaction, actual abrupt breaks in the continuity of the circuit are admissible. Reis chose this simple case as the one capable of being readily grasped by a general audience, though it was obviously only a partial explanation of the action of the apparatus in the simplest case that could be presented.

* * * * *

Turning now to some of the more modern transmitters, we will inquire how far Reis’s fundamental principles are involved in their construction. We will first take Berliner’s transmitter, of which Fig. 43 is a drawing, reproduced from the sketch in the specification of his British Patent. This transmitter consists of a tympanum of thin metal to collect the sound-waves, and behind it is attached an interrupter or current regulator, identical in almost every respect with that of Reis. One of the contact-pieces, marked _E_, circular in form, is fixed to the centre of the tympanum, and vibrates with it, precisely as in Reis’s latest, and in some also of his earlier instruments. Against this there rests in light contact a second contact-piece, in the form of a small blunt spike, _F_, screwed into a short arm, loosely jointed to the part _N_, where the circuit is connected. As in Reis’s latest transmitter (Fig. 17, p. 27), so here, the contact-pieces are kept in contact by gravity. When any person talks to the tympanum it vibrates, and, as a result, the degree of contact between the two surfaces is varied, resulting in a greater or less interruption of the current, the inertia of the upper contact-piece, serving to prevent complete abrupt “break” of the circuit, except under unusually strong vibrations. In fact, if the speaker talks too loudly when speaking into Berliner’s transmitter, he will cause abrupt breaks to occur instead of partial interruptions; and a rattling noise comes in to confuse the speech at the receiving end of the line. But this is precisely what occurs in a Reis’s transmitter if one talks too loudly to it. It is obvious that if Berliner’s transmitter is a “make-and-break” instrument, so is Reis’s, because the principle of action is identical: and it is also obvious that if Berliner’s instrument is capable of varying the resistance at the contact-points by interrupting the current in a manner corresponding to the pressures of the air in the sound-waves, so also is Reis’s instrument.

It is a fact that in Berliner’s instrument it is usual to make the contact-pieces, or one of them, of hard artificial coke-carbon, as this substance will neither fuse nor rust. But Berliner’s transmitter will transmit speech perfectly if the contact parts be of brass, silver, platinum, carbon, or almost any other good conductor. In most of Reis’s instruments the contact-pieces were usually of platinum; but they work quite as well if artificial coke-carbon is substituted. In fact, Reis’s principle of variable and elastic contact is applicable to contact-pieces of _any material that is a good enough conductor of electricity_ and hard enough for the purpose. The main improvement in Berliner’s transmitter is the substitution of the metal tympanum for the membraneous one, which was liable to become flabby with moisture.

We pass on to Blake’s transmitter, which is the one more generally used in Great Britain than any other. The drawing, Fig. 44, of this instrument is taken from the specifications of Blake’s British Patent, and shews all that concerns the contact-parts. It does not show the accessories, the induction-coil, or the form of adjusting screw and frame peculiar to this instrument. Inspection of the figure shows that this transmitter consists of a mouthpiece in the form of a conical hole bored through a stout plank of wood, and closed at the back by a metal tympanum of exactly the same size as that of Reis, behind which the interruptor is placed, precisely as in some of Reis’s instruments. In this interruptor both the contact-parts are supported on springs, resembling, even in the curve given to them, the springs Reis used. The first of the contact-pieces is a small metal spike. Concerning it Mr. Blake remarks (page 4 of Specification):--“It is desirable that it should be formed of, or plated with, some metal, like platinum or nickel, which is not easily corroded. It may be attached directly to the diaphragm, but I prefer to support it independently, as shewn, upon a light spring.” ... “This method of supporting the electrode _ensures its contact_ with the other electrode _under some circumstances when otherwise they would be liable to be separated and the circuit broken_.” In fact this spring serves functions precisely identical with those of the springs used by Reis. The second of the contact-pieces may be described as a mass of metal at the end of a spring. Of it the patentee remarks:--“This weight may be of metal which may serve directly as the electrode, but I have obtained better results by applying to it, at the point of contact with the other electrode, a piece of gas-coke or a hard-pressed block of carbon.” As a matter of fact, a mass of silver or of nickel or of platinum will transmit talking perfectly, but these metals, though better conductors, are more liable to corrode and fuse, and may require therefore more frequent renewal, than gas-coke. Since, then, it is immaterial to the action of a Blake transmitter what substance is used for the contact-pieces, it is clear that the principle of employing an interruptor mounted on springs is the real feature of the instrument. Reis also mounted his interrupters with springs, and for the very same purpose. The function of the weight on the second spring of the Blake transmitter is to resist the movement of the tympanum, and to “modify by its inertia the variations of pressure” between the two contact-pieces. In other words, it acts partly as Berliner’s transmitter, by inertia. So did one of Reis’s instruments, as we have seen. In the Blake instrument there is the happy idea of applying both the spring-principle and the inertia-principle at once. Yet, in spite of this, if the speaker shouts too loudly into a Blake transmitter, he will cause abrupt breaks between the contact-pieces instead of producing partial interruptions in the contact, and in that case speech will, as heard at the other end of the line, be spoiled by a rattling noise. It is possible, also, with Reis’s instruments to spoil the articulation by shouting too loudly, and causing actual abrupt breaks in the continuity. If Blake’s interruptor can be worked as a make-and-break in this sense, so can Reis’s: for there is not one of the features which is essential to Blake’s instrument that cannot be found in Reis’s also.

By way of further carrying out the comparison between Reis’s methods of combining his tympanum with his contact-regulator, and the methods adopted by later inventors, we give, in Fig. 45, ten comparative sketches, the first five of which illustrate Reis’s methods. In these sketches the only liberty taken is that of representing no more of the instruments than the actual parts wanted in the comparison. No. 1 represents the working-parts of Reis’s first model ear, with its curved lever, platinum-tipped spring, and adjusting screw. No. 2 shows the springs, screw, and contact-pieces of Reis’s bored-block transmitter (“fourth form:” compare Figs 9 and 10, p. 21). No. 3 shows the curved lever, the springs, and the adjusting screw of Reis’s eighth transmitter (“lever” form). No. 4 gives the working parts of Reis’s ninth transmitter, described in detail on p. 27. No. 5, in which the tympanum is placed in a vertical position, merely for convenience of comparison with the other figures, shows the working parts of Reis’s final form of instrument, in which gravity and the inertia of the upper contact-piece enabled him to dispense with the adjustment of spring and screw. No. 6 shows in profile Berliner’s transmitter, which may be instructively compared with No. 5. No. 7 shows the working part of Blake’s transmitter, which should be compared with Nos. 2 and 4: even the curve of the springs imitates that adopted by Reis. Nos. 8, 9, and 10 are forms of transmitter devised by Edison. No. 8 is copied from Fig. 10 of the specification of Edison’s British Patent. It will be seen that here there is an interruptor placed on each side of the tympanum, and that each interruptor consists of a short spike mounted on a spring and furnished with an adjusting-screw. “Platina foil disks,” says the inventor, are to be secured to each side of the diaphragm, and against these disks, as in Reis’s instruments, press the contact-points of the interruptors. The patentee also states (p. 7 of his Specification), that for these contact-points “any substance not liable to rapid decomposition” may be used. This term includes all the substances used by Reis, and a great many others. It will therefore be seen that this whole device is nothing more than a Reis transmitter with the contact parts duplicated. Yet this instrument was intended by Edison to transmit speech, and will, like Reis’s instrument, transmit speech if properly used. No. 9 of the set of sketches is taken from Fig. 25 of Edison’s British Specification, but omits the induction-coil and other accessories, retaining the parts wanted for comparison. The patentee thus describes the parts figured. “The tension-regulator [meaning thereby the interruptor or contact-regulator] is made of platina-foil upon the surface of two soft rubber tubes; one on the diaphragm, the other on the adjusting-screw.” It is interesting to note here how the ingenuity of the later inventor led him to vary the construction adopted by the original inventor in substituting an elastic cushion of soft rubber for the springs of the older instruments. But the principle of combining a tympanum with a contact-regulator, which was Reis’s fundamental notion, is here also the leading idea; and the further idea of obviating abrupt breaks in the current by applying elastic supports is also carried out. Edison even copies Reis in having an adjusting-screw, and he applies the very same substance--platinum foil--which Reis used in his very first and his very last transmitter. Edison’s transmitter transmits speech very fairly, even without any of such later accessories as induction-coils; and why should it not? It is constructed on the very lines, nay, with details almost identical with those prescribed by Reis in describing his invention. It embodies those fundamental ideas which Reis set before him when he said, “Taking my stand upon the preceding principles, I have succeeded.”

The last of the ten sketches of Fig. 45 is taken from Edison’s first American Patent specification [No. 203,014, filed July 20, 1877], and shows a duplicated interrupter with springs and adjusting-screws combined with a tympanum. Further comment on this arrangement is needless, save to remark that in this patent for “_speaking_ telegraphs,” Edison himself describes the contact-apparatus which Reis termed an “interrupter,” as a “circuit-closer,” or in another place as “circuit-breaking connections,” and, in his British Patent quoted above, as a “tension-regulator.” It is evident that if Reis could transmit speech by an interrupter which closed and opened the circuit (always in proportion to the vibrations) there is no reason why Edison seventeen years afterwards should not accomplish the same result by a similar means. But it has lately been fashionable to deny that any such device as an interrupter mounted on springs can transmit speech at all!

We have now compared with Reis’s transmitters several of the more modern inventions. It would be possible to carry comparison further were that course needed. We have not thought it worth while to rake up Edison’s now discarded lamp-black button transmitter; and we have not yet spoken of Crossley’s transmitter nor of Theiler’s transmitter, nor of their parent the Hughes’ microphone, nor of dozens of other forms. In some of these there is no specific “tympanum,” but only a sounding-board of pine-wood, and in most of them the points of loose-contact, where interruption more or less complete may occur, are multiplied. But they all come back in the end to Reis’s fundamental idea, namely that of setting the voice to vary the degree of contact in a mechanism which he called an interruptor, and which others have called a current-regulator (or, less correctly, a tension-regulator) which, because the degree of contact between its parts was varied, caused those parts to offer more or less resistance to the flow of the current, and thereby threw it into vibrations corresponding to those of the sound-wave impressed upon the tympanum. There is not a practical transmitter used in any of the telephone exchanges of Great Britain to-day that does not embody this principle.

Reis did, indeed, penetrate to the very heart the principles necessary to be observed in a successful telephone. He was master of the situation. For, as in every practical transmitter in use to-day, so in his transmitter, there was _a loose contact in the circuit so arranged that the voice could act upon it, and thereby regulate the strength of the current_. If you eliminate this part of the apparatus,--screw up the loose-contacts of your transmitters, so that your voices cannot affect them,--what will your telephones be worth? No: the essential principle of the transmitter--“Das Telephon” emphatically as its inventor styled it--is _variable contact_; and that all-essential principle was invented and applied for the purpose of transmitting speech by Philipp Reis in 1861.

If this does not suffice as a claim for the invention of the Telephone transmitter, it may well be wondered what will. We can dispense with all other features save this one. We can even dispense with the tympanum or diaphragm which Reis introduced, and can operate on the contact-parts without the intervention of this part of the combination. We can use the very metals which Reis used, and dispense with lamp-black and all the fallacious rubbish that has been subsequently devised about semi-conductors, whatever that term may mean. We can even dispense with springs and adjusting screws. _But with the principle of variable contact we can not dispense._ That which alone is indispensable Philipp Reis discovered.

APPENDIX II.

ON THE VARIATION OF ELECTRIC RESISTANCE AT A POINT OF IMPERFECT CONTACT IN A CIRCUIT.

Ever since electricians had experimented with voltaic currents, and especially since the introduction of the electric telegraph, it had been a familiar fact that a loose or imperfect contact in the circuit caused a resistance to the flow of the current and interrupted it more or less completely. To obviate the occurrence of loose or imperfect contacts, binding-screws were invented; and many were the precautions taken to make tight contacts at joints in the line, the resistance of which it was desirable to maintain at a minimum. Young telegraphists were particularly instructed to press their keys well down in signalling, because a light contact would offer some resistance which, on an increase of pressure, would disappear. In fact, it was generally well known that the resistance of two pieces of metal or other conducting material in contact with one another might be made to vary by varying the goodness or badness of the contact with the application of more or less force. This fact was known to apply to good conductors, such as copper and other metals, and it was known to apply also to non-metallic conductors, such as plumbago. Plumbago points were used by Varley for the contacts of relays; it having been found that points of platinum were liable to become fused together with the passage of the current, and by so sticking rendered the instrument useless. Since plumbago was known to be infusible, it was hoped that a plumbago contact would prove more reliable. In practice, however, the plumbago relay did not turn out so well. True it did not fuse, or stick, or rust; but it was even more liable than platinum to form imperfect contacts, the resistance of the light contact being so high that a sufficient current did not pass. It is not known whether other non-metallic substances were tried; probably not, because of non-metallic substances plumbago is one of the few that are good conductors.

According to Edison (British Patent, No. 792, 1882), compressed graphite is a substance of _great conductivity_. According to Faraday (‘Exp. Res.’ vol. i. p. 24), retort-carbon is an _excellent conductor_. Both graphite and retort-carbon agree with the metals in the property that the electric resistance offered at a point of contact between them varies when the pressure at the contact is varied. It is indeed remarkable through what wide ranges of resistance the contact between two good conductors may vary. The resistance of contact between two pieces of copper may be made to vary in a perfectly continuous manner by changes of pressure through a range, according to Sir W. Thomson, from a small fraction of one _ohm_, up to a resistance of many thousand _ohms_. The same is true of silver, brass, and many other good conductors, including graphite and retort-coke, though with the latter materials the range of resistances is not so great. With partial conductors, such as oxide of manganese, sulphide of copper, sulphide of molybdenum, &c., and with bad conductors, such as lamp-black and selenium, whose conductivity is millions of times less than that of graphite, copper, and other good conductors, it is impossible to get equally wide variations of resistance, as the amount of pressure at a point which will bring the bad conductors into intimacy of contact, will not turn them into good conductors. Platinum being in the category of good conductors, is amongst those substances which yield a very wide range of electrical resistances at the contact-points which are submitted to varying pressures.

With the very highest conductors, such as silver and copper, the electrical range of contact-resistance is higher than with those of lesser conductivity, such as lead, platinum, graphite, and retort-coke.

But though the range of variation in electrical resistance at contacts is highest for the best conductors, there comes in another element, namely, the range of distance through which the contact-pieces, or either of them, must be moved in order to pass through the range of variations of resistance. This is quite a different matter, for here the best conductors have the smallest range, and some that are not so good a greater range. In any case the available range of motion is very small--to be measured in minute fractions,--millionth-parts, perhaps,--of an inch. So far as experiments go, however, silver has the smallest range of all, then gold, then copper. Platinum and nickel have a considerably wider range, plumbago and retort-coke a still wider one.

It is an extremely difficult matter to decide what is the precise nature of that which goes on at a point of contact between two conductors when the pressure at the point is altered. The principal suggestions hitherto advanced have been that the change of resistance observed is due:--

(_a_) To the mere changes in the amount of surface in contact.

(_b_) To a change in the resistance of the substance of the conductor itself.

(_c_) To the formation of a minute voltaic “arc,” or electric discharge.

(_d_) To the change in the thickness of the intervening film of air.

(_e_) To the change in resistance of the parts in contact consequent on the evolution of heat by the current.

It is admitted that this last suggestion, though it might account for a difference between different substances, in so far as they differ from one another in the effect of heat upon their specific resistance, implies as a preliminary fact that the amount of surface in contact shall be varied by the pressure. No convincing proof has yet been given that the alleged layer of air or other gases has any real part to play in the phenomena under discussion. Nor can the hypothesis, that minute voltaic arcs are formed at the contact be regarded as either proven or probable.

The only two theories that have really been investigated are (_a_) and (_b_) of the above series. Of these two (_b_) is certainly false, and (_a_) is probably, at least to a very large extent, true.

It is often said by persons imperfectly acquainted with the scientific facts of the case, that carbon is used in telephone-transmitters, because the resistance of that substance varies with the pressure brought to bear upon it, whilst with metals no such effect is observed. This statement, taken broadly, is simply false. Mr. Edison has, indeed, laid claim to the “discovery” (_vide_ Prescott’s ‘Speaking Telephone,’ p. 223), that “semi-conductors,” including powdered carbon and plumbago, vary their resistance with pressure. All that Mr. Edison did discover was that certain substances, whose properties of being conductors of electricity had been known for years, conducted better when the contact between them was screwed up tightly than when loose. The experiments made to test this alleged “property” of carbon are absolutely conclusive. The author of this book has shown[39] that when a rod of dense artificial coke-carbon, such as is used in many forms of telephone transmitters, such as Crossley’s for example, is subjected to pressure varying from less than one dyne per square centimetre up to twenty-three million times that amount, the resistance of the rod did not decrease by so much as one per cent. of the whole. In this case any doubt that might have been introduced by variable contact was eliminated at the outset by taking the precaution of electro-plating the contacts.

In 1879, Professors Naccari and Pagliani, of the University of Turin, published an elaborate series of researches[40] on the conductivity of graphite and of several varieties of coke-carbon, and found, even with great changes of pressure, that the changes of electric resistance were practically too small to be capable of being measured, and that the only changes in resistance appreciable were due to changes of contact.

In January 1882, Mr. Herbert Tomlinson communicated to the Royal Society[41] the results of experiments on a number of electric conductors. The change of conductivity by the application of stress was found to be excessively small. For carbon it was less than one-thousandth part of one per cent. for an increase of fifteen lbs. on the square inch in the pressure. For iron it was slightly greater, and for lead nearly twice as great, but with all other metals less. If this alleged property were the one on which the action of telephone transmitters depended, then lead ought to be twice as good a substance as graphite; whereas it is not nearly so good.

Professor W. F. Barrett, in 1879,[42] made some experiments on the buttons of compressed lamp-black used in Edison’s transmitter, and found that when an intimate contact was satisfactorily secured at the beginning, “pressure makes no change in the resistance.”

In the face of all this precise evidence, it is impossible to maintain the theory that the electric resistance of plumbago or of any other such conductor varies under pressure. The only person who has seriously spoken in favour of the theory is Professor T. C. Mendenhall, but in his experiments he took no precautions against variability of contacts, so that his conclusions are invalid.

More recently still, Mr. O. Heaviside and Mr. Shelford Bidwell have experimented on the variations of resistance at points of contact.[43] Mr. Heaviside’s experiments were confined to contacts between pieces of carbon, and though extremely interesting as showing that the resistance of such contacts are not the same, even under constant pressure, when currents of different strength are flowing, do not throw much light on the general question, because they leave out the parallel case of the metals. Mr. Bidwell’s very careful researches were chiefly confined to carbon and bismuth. The choice is unfortunate, because bismuth the most fusible and worst conductor amongst metals (save only quicksilver) is the one metal _least_ suited for use in a telephone transmitter. Mr. Bidwell’s conclusions, so far as they are comparative between carbon and “the metals,” are therefore necessarily incomplete.

Professor D. E. Hughes, whose beautiful invention, the Microphone, attracted so much attention in 1878, has lately thrown the weight of his opinion in favour of the view that with carbon contacts the effect is due chiefly to an electric discharge or arc between the loosely-contiguous parts. But Professor Hughes’s innumerable experiments entirely upset the false doctrine that a “semi-conductor” is necessarily required for the contact-parts. Speaking recently,[44] he has said: “I tried everything, and everything that was a conductor of electricity spoke.” In 1878, in a paper “On the Physical Action of the Microphone,” Professor Hughes stated:[45] “the best results as regards the human voice were obtained from two surfaces of solid gold.” Hughes also found carbon impregnated with quicksilver in its pores to increase its conducting power to work better than non-metallised carbon of inferior conductivity. Quite lately Mr. J. Munro has constructed successful transmitters of metal gauze, having many points of loose-contact between them.

It seems, therefore, much the most probable in the present state of investigations, that the electric resistance of a contact for telephonic purposes is determined solely by the number of molecules in contact at the surface, and by the specific conductivity of those molecules. The element of fusibility comes in to spoil the constancy of the surfaces in action; and hence the inadmissibility of general conclusions with respect to all metals drawn from the behaviour of the most fusible of them. At a mere point in contact physically with another point, there may be hundreds or even millions of molecules in contact with one another, all acting as so many paths for the flow of the electric current. An extremely small motion of approach or recession may suffice to alter very greatly the number of molecules in contact, and the higher the specific conductivity of the substance, and the denser its molecules, the shorter need be the actual range of motion to bring about a given variation in the resistance offered. Just as in a system of electric lamps in parallel arc, the resistance of the system of lamps increases when the number of lamps through which the current is flowing is diminished, and diminishes when the number of lamps connecting the parallel mains is increased; so it is with the molecules at the two surfaces of contact. Diminishing the number of molecules in contact increases the resistance, and _vice versâ_. Each molecule as it makes contact with a molecule of the opposite surface diminishes, by so much relatively to the number of molecules previously in contact, the resistance between the surfaces. Each molecule as it breaks from contact with its opposite neighbour adds to the resistance between the contact-surfaces. It may therefore be that the variations of resistance which are observed at contacts between all conductors, from the best to the worst, are all made up, though they _appear_ to pass through gradual and continuous changes, of innumerable minute makes-and-breaks of molecular contact. The very minuteness of each molecular make-or-break, and the immense number that actually must occur at every physical “point” of contact, explain why the effect seems to us continuous. We owe, moreover, to Mr. Edison[46] the experimental proof that actual abrupt makes-and-breaks of contact _can_ produce an undulating current when they recur very rapidly. Whether the heating action of the current itself may not also operate in changing the conductivity of the molecules which happen at the moment to be in contact is another matter. It may be so; but if this should hereafter be demonstrated, it will but confirm the contact-theory of these actions as a whole.

Assuming, then, broadly, that the observed resistance at a point of contact is due to the number of molecules in contact and to their individual resistances, it is evident that the property of varying resistance at contact ought to be most evident, _ceteris paribus_, in those substances which are the best conductors of electricity. Unfortunately, the _cetera_ are not _paria_, for the question of fusibility comes in to spoil the comparison; and carbon, which has less fusibility than the metals, is commonly credited with giving a better result than any. This common opinion is, however, based on comparisons made without taking into consideration the question of range of motion between the parts in contact, and without taking into consideration the point that whilst some forms of carbon are excellent conductors, others do not conduct at all. In a telephonic transmitter so arranged that the actual range of motion shall be very small, the metals are just as good as carbon--some of them better. I have heard from a transmitter with contacts of pure bright silver better articulation than with any carbon transmitter. And this is exactly what theory would lead one to expect. As to the suggestion that plumbago makes a successful transmitter, because it is a “semi-conductor”--whatever that term may mean[47]--it is one of those suggestions which are peculiarly fitted to catch the unscientific mind as affording an easy explanation for an obscure fact; unfortunately, like a good many other similarly catching suggestions, _it is not true_. The very best conductor--_silver_--will serve to transmit articulate speech: and so will the one of the very worst conductors--_lamp-black_! So much for this fallacious doctrine of semi-conductors!

Reis used for his contact-points substances which, by reason of their non-liability to fuse or oxidize, were customary in electrical apparatus, and chiefly platinum. In his earliest transmitter (model ear), and in his last, platinum was used. In his lever-form of transmitter, so minutely described by von Legat, the material is not specified. The lever-shaped contact-piece was to be a conductor, and as light as possible, and since all metallic parts are particularly described as metallic, whilst this is not so described, the obvious inference is that this was non-metallic. The number of light, non-metallic conductors is so few that the description practically limits choice to some form of hard carbon. No other materials are named by Reis, but Pisko says (p. 103) that brass, steel, or iron might be used for contacts. Any one of these materials is quite competent, when made up into properly-adjusted contact-points, to vary the resistance of a circuit by opening and closing it in proportion to the vibrations imparted to the contact-points. That is what Reis’s transmitter was intended to do, and did. That is what all the modern transmitters--Blake’s, Berliner’s, Crossley’s, Gower-Bell’s, Theiler’s, Johnson’s, Hunning’s do, even including Edison’s now obsolete lamp-black button transmitter. Mr. Shelford Bidwell has very well summarized the action of the current-regulator in the following words: “The varying pressure produces alterations in the resistance at the points of contact in exact correspondence with the phases of the sound-waves, and the strength of a current passing through the system is thus regulated in such a manner as to fit it for reproducing the original sound in a telephone.”

Reis constructed an apparatus consisting of a tympanum in combination with a current-contact-regulator, or “interruptor,” which worked on this principle of variable contact, and he called it “The Telephone” (see pp. 57, 85). The very same apparatus we now-a-days call a “Telephone-transmitter,” or simply a “transmitter.” It is curious to note that Reis seems to have regarded his receiver or “reproducing-apparatus” as no new thing. He says explicitly (p. 56) that his receiver might be replaced by “any apparatus that produces the well-known galvanic tones.” “_The_ Telephone” was with Reis emphatically the _transmitter_. Bell in 1876 invented an instrument which would act either as transmitter or receiver, and which, though never now used as transmitter, is still called “a Telephone.” Edison’s “sound-telegraph,” or “telegraphic apparatus operated by sound,” was patented in 1877. In his specification _he never called his transmitter a “telephone_;” that name he reserved exclusively for his receiver. He found it, however, convenient a year later to rechristen his transmitter as the “_carbon telephone_,” though throughout the whole of his specification _neither “carbon” nor “telephone” are mentioned_ in connection with the transmitter! Within that year Hughes had brought out another instrument--“The Microphone”--which, like Reis’s instrument, embodied the principle of variable contact. Hughes’s instrument, usually constructed with contacts made of loose bits of coke-carbon, was simply a Reis’s Telephone minus the circular tympanum; and the really important new fact it revealed, was that very minute vibrations, such as those produced by the movements of an insect, when transmitted immediately through the wooden supports, sufficed to vary the resistance of a telephonic circuit, though far too slight in themselves to affect it if they had to be first communicated to the air and then collected by a tympanum. Put a specific tympanum to a Hughes’s microphone, and you get a Reis’s telephone. Take away the tympanum from a Reis’s telephone, and you get a Hughes’s microphone. Hughes is not limited to one material, nor is Reis. But the fundamental principle of the electrical part of each is identical. The Blake transmitter (Fig. 44), and the Berliner transmitter, and also Lüdtge’s microphone,[48] which was even earlier than that of Hughes, are all embodiments of the same fundamental principle of variable contact which Reis embodied in his “Telephone.”

The numerous experiments which Reis made, and the many forms of instruments which he devised, prove his conviction of the importance of his invention to have been very deeply rooted. He had indeed penetrated to the very soul of the matter. He did not confine himself to one kind of tympanum, he tried many, now of bladder, now of collodion, now of isinglass, and now of thin metal. He varied the forms of his instruments in many ways, introducing the element of elasticity by springs and adjusting-screws. Though he chiefly employed one metal for his contact-pieces, he did not limit himself to that one, but left us to infer that the principle of variable contact was applicable to any good conductor, metallic or non-metallic. He knew better, indeed, than to limit himself in any such fashion; better, indeed, than some of the eminent persons who are now so willing to ignore his claims. Modern practice has taught us to improve the tympanum part of Reis’s invention, and to obviate the inconveniences to which a membrane is liable: in that part we have gone beyond Reis. But in the question of contact-points for opening and closing the circuit in correspondence with the vibrations, we are only beginning to find how much Reis was a-head of us. We have been thrown off the track--blinded perhaps--by the false trail of the “semi-conductor” fallacy, or by the arbitrary and unnatural twist that has been given by telegraphists to Reis’s expression, “opening and closing the circuit,” forgetting that he practically told us that this operation was to be proportional to, “in correspondence with,” the undulations of the tympanum. When we succeed in freeing ourselves from the dominance of these later ideas, we shall see how much we still have to learn from Philipp Reis, and how fully and completely he had grasped the problem of the Telephone.

FOOTNOTES:

[39] ‘Philosophical Magazine,’ April 1882.

[40] ‘Atti del R. Istituto Veneto di Scienze,’ vol. vi. ser. 5.

[41] Proc. Roy. Soc. No. 218, 1882.

[42] See Proc. Roy. Dubl. Soc. Feb. 17, 1879.

[43] Vide ‘The Electrician,’ Feb. 10, 1883.

[44] Journal Soc. Telegr. Engin. and Electricians, vol. xii. p. 137.

[45] Proc. Physical Soc. vol. ii. p. 259, 1878.

[46] ‘Journal Soc. Telegraphic Engineers,’ vol. iv. p. 117, 1874.

[47] The term “semi-conductor” is very rarely used by electricians, who prefer the term “partial conductor” as being more correct. Moreover, electricians, from Faraday downwards, are practically agreed in calling plumbago a good conductor, and worthy of being classified by reason of its high conductivity along with the metals. The substances known as “semi-conductors” are those given in Ferguson’s ‘Electricity,’ p. 49 (edition of 1873), namely, alcohol, ether, dry-wood, marble, paper, straw, and ice. Mascart and other eminent authorities agree in this classification. It would tax even Mr. Edison’s unrivalled ingenuity to make of these materials a transmitter that should alter its resistance by pressure!

[48] Lüdtge’s German Patent, dated Jan. 12, 1878, describes a “Universal Telephone” in which a tympanum was applied to convey vibrations to an interruptor made of hard coke-carbon.

APPENDIX III.

COMPARISON OF REIS’S RECEIVERS WITH RECENT INSTRUMENTS.

The receivers invented by Reis for the purpose of reconverting into audible mechanical vibrations the varying electric currents transmitted from the speaking end of the line were of two classes, viz.:

(1.) Those in which the magnetic expansion and contraction of a rod of steel or iron, under the influence of the varying current, set up mechanical vibrations and communicated them to a sound-board.

(2.) Those in which the current by passing round the coils of an electro-magnet caused the latter to vary the force with which it attracted its armature, and threw the latter into corresponding mechanical vibrations.

The first of these principles is embodied in the “knitting-needle” receiver described above and depicted in figures 22 & 23 on page 33. This receiver differs wholly from the later instruments of Bell, and others, and depended for its action upon the phenomenon of magnetic expansion discovered by Page and investigated by Joule. It was well known before Reis’s time that when a needle or bar of iron was magnetised it grew longer, and when demagnetised it grew shorter. Page detected the fact by the “tick” emitted by the bar during the act of magnetisation or demagnetisation. Joule measured the amount of expansion and contraction. To these discoveries Reis added two new facts; _first_, that if the degree of magnetisation be varied with rapid fluctuations corresponding to those of the sound waves impressed on the transmitter, the expansion and contraction of the rod followed these fluctuations faithfully, and therefore emitted at the receiving end sounds similar to those uttered at the transmitter. _Secondly_, by employing a needle of _steel_ instead of the bar of iron used by Page, Reis obtained an instrument which once used could never become completely demagnetised on the cessation of the current; it was thenceforth a _permanent magnet_, and all that the fluctuating currents could do was to vary its degree of magnetisation. Reis carefully explained in his memoir “On Telephony,” how the frequency of such fluctuations in the magnetising current could act in reproducing the pitch, and further, how the amplitude of the fluctuations set up vibrations of corresponding amplitude in the rod: he added with significance, that the quality of the reproduced note depended upon a number of variations of amplitude occurring in a given time. His theory of these actions was that the atoms (or perhaps our modern word _molecules_ would more correctly represent what Reis spoke of as atoms) of the rod or needle were pushed asunder from one another in the act of magnetisation, and that on the cessation of the magnetising influence of the current, these same atoms strove to return to their previous position of equilibrium, and thus the oscillations of the atoms led to the vibration of the needle as a whole. Whether all Reis’s speculations as to the behaviour of the atoms under varying degrees of magnetising force are justified in the present aspect of science or not, is, however, not of any great importance; the important point is, that, whether his theory be right or wrong, the instrument he devised will perform the function he assigned to it: it will reproduce speech, not loudly, but in reality far more articulately than many of the telephonic receivers in use under the names of Bell, Gower-Bell, &c.

One very curious point in connection with this “knitting-needle” receiver of Reis, is its extremely bad acoustical arrangements. It was laid horizontally upon a small sounding-box covered by a lid. If the _end_ of the needle had been made to press on the resonant-board (as indeed appears to have been done at first with the violin, p. 29) the vibrations would have been much more directly reinforced. But when merely supported by two wooden bridges the direct communication was largely lost. The pressure of the lid downwards upon the spiral, as recommended by Reis, is no doubt an important matter acoustically. It is strange that a man who had grappled in so masterly a way with the acoustical problem of the transmitter, and had solved it by constructing that transmitter on the lines of the human ear, should not have followed out to the same extent those very same principles in the construction of his receiver. An extended surface he did employ, in the shape of a sounding-board; but it was not applied in the very best manner in this instrument.

The second principle applied by Reis in the construction of his telephone-receivers, was that of the electro-magnet. He arranged an electro-magnet so that the fluctuating currents passing round the coils set up corresponding variations in the degree of force with which it attracted its armature of iron, and so forced the latter to execute corresponding mechanical vibrations. This principle is common both to the receiver of Reis, and to the later receivers of Yeates, Bell, and Edison. Reis’s armature was an iron bar of oval section; Yeates’s an iron strip screwed to a sound-board, Bell’s was an iron plate, and Edison’s an iron plate also.

For the better comparison of Reis’s electro-magnetic receiver with those of more modern date, we here present in Fig. 46 a comparative view of a number of different forms of receiver in which Reis’s principle of causing an electro-magnet to set up vibrations in an armature is applied. In this set of figures, _A_ and _B_ are the suggested forms mentioned in the letter of Mr. Horkheimer, p. 119, and show an electro-magnet, opposite the poles of which is placed an armature (a bar) which must be of iron or other metal capable of having magnetism induced in it, and which, by reason of its attachment to an elastic spring, is capable of being made to oscillate to and fro when attracted with a varying force. Reis clearly recognised the necessity of further providing a sufficient resounding surface by means of which the surrounding air could be set in motion: for in the case of these two suggestions the electro-magnet and its elastically-mounted armature were placed within a cigar box. _C_ is a plan of the receiving instrument previously described and figured in Plate II. and in figures 21 and 34 on pages 32 and 109. In this instrument the electro-magnet was horizontal, the armature, a bar of iron of oval section (which in the original drawing in plate II. appears to have been in reality a hollow bar or tube) attached to a thin lever described as a plank, pivoted like a pendulum to an upright support, but prevented by a set-screw and a controlling spring from vibrating in the manner of a pendulum. Such an arrangement, in fact, vibrates in perfect correspondence with any vibrations that may be forced upon it by the electro-magnet. The broad flat surface of the lever--he specially directed that it should be broad and light--transfers the vibrations to the air, and is aided by the surface of the sounding-board on which the apparatus stands. This apparatus has, therefore, all the elements of a successful receiver, except only that its shape renders it inconvenient for portability. But by reason, firstly of its armature of iron, secondly of the elastic mounting of that armature, thirdly of the extended surface presented, it is admirably adapted to serve as an instrument for reproducing speech.

Fig. 46 _D_ represents the excellent electro-magnetic receiver devised in 1865 by Yeates (compare Fig. 42, p. 128) to work with the Reis transmitter, and is in many respects identical with the preceding form. The armature, a strip of iron, was attached at one end by a very stiff steel spring to a pine-wood sounding-board over a hollow box, from the base of which rose the metal pillar which supported the electro-magnet. This receiver also contains all the elements of a successful receiver, the armature being of a material capable of inductive action, and elastically supported; whilst the sound-box provided adequate surface to communicate the vibrations to the air.

We now come to the more modern instruments of Gray, Bell, and Edison. So far the receivers of Reis and of Yeates were intended for reproducing any sound; but now for the first time, ten years after the date of these early telephonic receivers, we meet with instruments devised with the express purpose of receiving only certain selected tones.

For the purposes of multiple acoustic telegraphy, that is to say for the purpose of signalling the “dots” and “dashes” of the Morse code in a number of different fixed musical notes, each of which is to be signalled out and repeated by a receiver adapted to vibrate in that note alone, it is clear that the instruments of Reis, adapted as they were to transmit and receive _any_ sound that a human ear can hear, would not answer. Accordingly those experimenters, who from about the year 1873 to the year 1870, applied themselves to multiple telegraphy--foremost amongst them being Mr. Elisha Gray and Prof. Graham Bell--dropped the use of the tympanum in the transmitter and devised new transmitters and new receivers, in most of which the ruling idea was that of employing a vibrating tongue or reed, tuned up to one particular note. Now it is obvious that a receiver which, like those of Reis, is adapted to receive _any_ tone, can also receive a musical note. But for the operation of “selective” reception, a receiver must be employed, not only tuned to one note, but tuned to the very note emitted by the particular transmitter with which it is to be in correspondence. Elisha Gray found this out very early in his researches. In the winter of 1873-4[49] he was transmitting musical tones by a sort of tuning-fork interruptor, and received them on an instrument shown in Fig. 46 E, which represents a form of electro-magnet mounted for the purpose. It was “a common electro-magnet, having a bar of iron rigidly fixed at one pole, which extends across the other pole, but does not touch it by about one sixty-fourth part of an inch. In the middle of this armature a short post is fastened, and the whole is mounted on a box made of thin pine, with openings for acoustic effects.” It was, in fact, very similar to Yeates’s receiver just described, and Gray found it capable of receiving not only simple musical tones but composite tones, and even harmonies and discords. In fact, like Reis’s and Yeates’s receivers, it could receive anything that the transmitter sent to it, even including speech. Now this did not suit Gray, who wished to have selective receivers, one to take up note A, another note C, &c. Accordingly in 1870 we find Gray taking out a fresh patent[50] for selective receivers, which he also called harmonic analysers, each of which consisted of “a tuned bar or reed suitably attached to an electro-magnet, and the whole mounted upon a resonant box.” Fig. 46 _F_ is reproduced from Gray’s British patent. “A vibrating tongue reed, or bar” of steel “is united with one pole of the magnet. The free end of the reed passes close to, but does not touch the other pole of the magnet.” Gray further says that the reed is made with parallel sides and tuned by cutting it away at one point, as this mode prevents false nodal vibrations from occurring.

Selective receivers for multiple telegraphy were also invented by Graham Bell. The form shown in Fig. 46 _I_ is transcribed from Fig. 15 of Bell’s Specification to his British Patent, No. 4765, of the year 1876 (dated 9th December), which the inventor thus describes: “It is preferable to employ for this purpose an electro-magnet _E_, Fig. 15, having a coil upon only one of its legs. A steel spring armature _A_ is firmly clamped by one extremity to the uncovered leg _h_ of the magnet, and its free end is allowed to project above the pole of the covered leg.” In fact the arrangement was almost identical with, but not quite as good mechanically as that patented seven months previously by Gray. The inventor further said that a number of these instruments might be placed on one circuit, and that if one of them were set in vibration, only those would respond which were in unison with its note; and further that “the duration of the sound may be used to indicate the dot or dash of the Morse alphabet, and thus a telegraphic despatch may be indicated by alternately interrupting and renewing the sound.”

Anything more totally different from Reis’s telephone than these selective harmonic telegraphs with their tuned tongues can hardly be imagined. Reis was not aiming at selective harmonic telegraphy; he wanted his one instrument to transmit every sound that a human ear could hear. He did not dream of using a tuned bar or reed; his typical structure was the tympanum of the ear. In fact, as we have seen above, the tuned reed or tongue was introduced into telegraphy for the purpose of transmitting single selected notes to the exclusion of all others.

Strange though it may seem, a tongue receiver like those of Graham Bell and of Gray just described can be used for receiving speech! It is true, as Gray remarks, that a thick bar of steel, cut away as described, is best adapted for its own tone only. But Bell’s thin steel tongue, though it has its own fundamental note (and so has every tympanum, for that matter) when left free to vibrate in its own time, will reproduce _any_ other note or sound that may be _forced_ upon it by the varying attraction of the electro-magnet. There is, indeed, the whole difference between “free” and “forced” vibrations. One of the strangest delusions that has somehow grown up in recent telephonic discussions is the almost incredible proposition that a tongue cannot talk because it is a tongue. It would be equally veracious to affirm that an ear (_i.e._ a tympanum) cannot hear because it is an ear.

But leaving harmonic telegraphy and its “tuned bars,” both Gray and Bell applied themselves to the old problem of transmitting human speech. What was their very first step? They threw away their “tuned bars” and “steel springs,” and returned _to the tympanum_! Elisha Gray devised the receiver shown in Fig. 46, _G_, taken from his caveat of date February 14, 1876.[51] In that document Gray says: “My present belief is that the most effective method of providing an apparatus capable of responding to the various tones of the human voice, is a _tympanum_, drum, or diaphragm,” stretched across one end of a chamber. He adds that in the receiver there is (see Fig. 46, _G_) an electro-magnet, acting upon a diaphragm to which is attached a piece of soft iron, and which diaphragm is stretched across a vocalising chamber.

Graham Bell’s receiver (the American specification of which was filed the same day as Gray’s caveat) is shown (in the form patented in Great Britain, Dec. 9, 1876) in Fig. 46 _H_, which is taken from Fig. 19 of Bell’s British patent. “The armature,” says the inventor, “is fastened loosely by one extremity to the uncovered leg, _h_, of the electro-magnet _E_, and its other extremity is attached to the centre of a stretched membrane.” The armature, in fact, was capable of vibrating like a pendulum on its pivot, but was elastically restrained by its attachment to the tympanum; the armature would therefore vibrate in perfect correspondence with any vibrations forced upon it by the electro-magnet. This instrument as also that of Gray, was admirably adapted to receive speech, for it embodied the three essential points which Reis had already discovered: viz., firstly, that the armature must be of iron, or capable of being acted upon by magnetic induction; secondly, that it must be elastically mounted; thirdly, that it should present an extended surface. Bell’s form of receiver had the advantage over Reis’s (compare p. 158), that its extended surface was a true tympanum of membrane, and not a mere broad thin plank. Being a tympanum, it therefore realised Reis’s fundamental notion of imitating the human ear more fully than even Reis’s own receiver did.

Figures 46, _J_, _K_, and _L_ represent the more recent types of receiver of Bell and Edison. Fig. 46 _J_ is reproduced from Fig. 20 of Bell’s British Patent, and shows the substitution of a thin steel plate, attached to a frame, in front of the electro-magnet, for the membrane and iron armature. This form of instrument also embodies Reis’s three principles--but with this improvement, the armature capable of inductive action, the elastic mounting, and the extended surface, are here all united in one organ, the thin flexible tympanum of steel. Apart from this unification of parts there is absolutely nothing in this form of Bell’s receiver, that Reis did not invent fourteen years before. Bell’s great and most signal improvement was not this beautiful mechanical modification of the Reis receiver, but lay in the entirely new suggestion to use such a receiver _as a transmitter_ to work by magneto-electric induction. Two of Reis’s receivers (Fig. 21) if coupled up with a battery will talk together as transmitter and receiver: but Reis did not know and never suggested this. Two of Yeates’s receivers (Fig. 42) if coupled up with a battery will talk together as transmitter and receiver; but Yeates did not know and never suggested this. Bell did discover this, and thereby invented a transmitter which, though now abandoned as a transmitter, for want of loudness, was more reliable than the anterior transmitters of Reis had been. He made another discovery, presently to be alluded to--that of putting a permanent magnet into the transmitter, to enable him to dispense with the battery; but beyond this and the other mechanical simplifications previously mentioned, all that he discovered may be summed up by saying that he found out that a receiver constructed on Reis’s principles could work as a transmitter also. That was Bell’s really great and important discovery which took all the world by storm at the Centennial Exhibition of 1876.

Bell subsequently added to his claims the substitution of a permanent magnet with an iron pole-piece, in place of the simple electro-magnet, thus enabling him to transmit his fluctuating currents without the trouble of using a battery, and the Bell transmitter, thus modified, is used to this day as a receiver, Reis had in his “knitting-needle” telephone, employed a permanent magnet of steel to serve as a receiver, he had not, however, applied it as Bell did to attract a plate of thin steel.

Fig. 46, _K_, exhibits a form of electro-magnetic receiver described in Edison’s British Specification, No. 2909, 1877, Fig. 24. This instrument, though patented seven months after Bell’s instrument, differs from it in no point of importance. Its armature was a thin plate of iron, elastic, and having an extended surface; being, in fact, a tympanum.

No one can examine the set of receiving instruments collected in Fig. 46 without being struck with the extraordinary similarity of design which pervades the entire series. In every one of the set there is an electro-magnet, the function of which is to set an armature[52] into vibration by attracting it with a variable force. In every one the armature is of a material capable of magnetic induction; that is to say, iron, steel, or equivalent material. In every one of them the armature is either elastically mounted, or is in itself elastic. In every one of them (save only the two quite recent forms, _F_ and _I_, which were intended not to speak, but to emit only one fixed musical note) there is an extended surface (either a sound-board or a tympanum) to communicate the vibrations to the air. Lastly, every one of these forms, when connected with the line through which the telephonic currents are being transmitted, is perfectly capable of reproducing articulate speech. But the inventor who had the genius to discover all these essential points, and to combine them in an instrument, and to use it to reproduce articulate speech, is surely the true inventor of the system. The inventor of the system embodying these essential points was Philipp Reis.

FOOTNOTES:

[49] See Prescott’s ‘Speaking Telephone,’ p. 158.

[50] ‘British Patent,’ No. 1874, of the year 1876 (dated 4th May).

[51] Prescott, ‘Speaking Telephone,’ p. 203.

[52] Yet Bell’s claim (British Patent Specification) runs: “I claim the production of any given sound or sounds from the _armature_ of the receiving instrument.”

APPENDIX IV.

ON THE DOCTRINE OF UNDULATORY CURRENTS.

“_In this Specification the three words ‘oscillation,’ ‘vibration’ and ‘undulation,’ are used synonymously._”--Graham Bell, U.S. Patent, No. 174,465, filed Feb. 14, 1876.

In the preceding appendices it has been demonstrated that all that is essential in both transmitter and receiver of a Telephonic system was to be found existing in 1863 in the Telephone of Reis. There yet remains to be met the _doctrinaire_ objection that as Reis never explicitly mentions an undulatory current as distinguished from an intermittent one, he never intended to use such a current. This objection is advanced only by those persons who have committed themselves to the idea that speech cannot be transmitted by a transmitter which opens and closes the circuit.

It is certain that Reis did not in any of his writings explicitly name an undulatory current: but it is equally certain that, whether he mentioned it or not, he both used one and intended to use one. He did not concern himself as to the precise manner in which the current fluctuated provided only he attained the end in view--namely, that the vibrations of the armature of the receiver should be similar to those of the transmitter. This he did lay down with great clearness and emphasis as his guiding principle; and he cared not about the intermediate question as to how the current did the work. He told the world that the electromagnet at the receiving end must be magnetised and demagnetised correspondingly with the vibrations imparted by the air to the tympanum of his transmitter, in order that the armature might be set into vibrations similar to those of the speaker’s voice. If the tympanum of the transmitter vibrated or oscillated or undulated--the terms are synonymous--so must the armature of the receiver. Graham Bell has told us precisely the same thing: “The current traversing the coils of the electromagnet _E_ occasions an increase and diminution in its intensity” [that is to say, magnetises and demagnetises it], “and the armature _A_^1 is thrown into vibration” ... “and thus imparts to the air at _n_^1 a facsimile copy of the motion of the air that acted upon the membrane _n_.” Bell agrees then absolutely in every detail with what Reis said on this point. That sound-waves should be transmitted by a Telephone requires indeed a process of several stages. (1.) The sound-waves must strike upon the tympanum of the transmitter and make it undulate, or, oscillate, or vibrate--whichever term you please--in a corresponding manner. (2.) The undulating tympanum must act upon the circuit, and either itself induce undulating or vibrating currents (Bell’s plan, by magnetic induction), or else throw a current already flowing there, into undulations, or vibrations, or oscillations (Reis’s plan, by varying contact-resistance), but in either case these undulations of the current must correspond to the original undulations of the air-waves. (3.) The undulating, or vibrating, or oscillating current must run round the coils of the electromagnet and cause its magnetic force to undulate, or oscillate, or vibrate by demagnetising it and then magnetising it, but this also must be in a manner corresponding to the original undulations. (4.) Further, the armature of the receiver must be set into undulations, or vibrations, or oscillations corresponding to those of the force of the electromagnet, and therefore to the undulations of the current that is magnetising and demagnetising it, and therefore identically corresponding with the original undulations of the sound-waves. (5.) The armature must communicate its vibrations to the air and to the ear of the listener. Of these successive stages Reis explicitly told the world that his instrument was to do the first one and the last three, and he several times emphasized the statement, that the final undulations of the last stage were to be similar to the original undulations of the first stage. The air at the listening end, the armature of the receiver, and the magnetism of the magnet, were all to be set by the fluctuations of the current into undulations corresponding with those of the tympanum at the speaker’s end, and of the waves of his voice. It is perfectly clear therefore, that he regarded as self-evident the intermediate stage, and he did not dwell upon the necessity of the point, that his transmitting-current must also vibrate, because this was obviously so, and was only an intermediate matter of secondary moment. He chose rather to point out the necessity of unification between the first and last stages, leaving it to common sense to see that the “interruption” or the “opening and closing” of the circuit must be effected in a manner corresponding to the undulations of the impressed sound-wave. Had the “interruptions” not been of the nature of corresponding variations of contact, the current could not have been set into corresponding vibrations, and the armature of the electromagnet could not have reproduced the vibrations of the transmitter. Clearly Reis’s whole conception of telephony included as a minor and intermediate step the fact that the current was, by the action of the transmitter, caused to vary in strength in correspondence with the undulations of the tympanum--that, in fact, it was made to undulate by the action of the tympanum and of the interruptor which opened and closed the circuit in obedience to the undulations of the tympanum and in proportion to them.

A difficulty has been raised by telegraph operators that opening and closing the circuit means opening and closing the circuit in abrupt alternations of make-and-break. Reis never said so. Reis never used the phrase in this restricted and technical sense. He was not a professional telegraphist, and, as pointed out in Appendix I., he so arranged his contacts with the following springs and other contrivances, that the “opening and closing” of the circuit should not and could not be abrupt. A Reis transmitter is no more a “make-and-break” instrument than the Blake transmitter is. Both will give undulatory currents by opening and closing the circuit to a greater or less degree, if spoken gently to. Both will give abrupt makes-and-breaks of the circuit if shouted to, in spite of the following-springs, which are used to prevent abrupt interruptions. The term “opening and closing” which Reis applied to his transmitter, is used by him in exactly the same way as the phrase is used by engineers in describing the action of the governing throttle-valve of a steam-engine. The function of the governor, we are told in treatises on engineering, is to open and close the throttle-valve in a manner corresponding to the fall or rise of the governor-balls. No one in his senses imagines that the opening and closing action here referred to means an absolutely abrupt intermittence in the supply of steam. If the governor-balls rise a little by increase of speed, there is a corresponding closing, proportionate in amount to the amount of rise. If any person were to impress an oscillatory motion of rise and fall upon the governor, the supply of steam would be thrown into corresponding undulations. The matter stands precisely so with Reis’s “interruptor” or “regulator;” it opens and closes the circuit in a manner corresponding with the undulations communicated to it. If it did not, it would violate the principle of correspondence so emphatically laid down by Reis.

It is, however, true that Reis’s instruments, in spite of springs and adjusting screws, and other devices to prevent abrupt make-and-break occurring, were prone, by reason of the very lightness of the parts, to break contact, if too loudly spoken to. They share this fault with the more perfect transmitters of Blake and Berliner which are used to-day so generally. The undulatory currents of these transmitters are, like those of Reis’s transmitters, liable to an occasional abrupt interruption, which, though it may not seriously affect the intelligibility of the words, does, to some extent, mar the perfection of the articulation. Still, in practice, to judge by the instruments used in the telephone exchanges of Great Britain, the Blake transmitter with its liability to make-and-brake abruptly is a more satisfactory instrument than the Bell transmitter, which is not used at all. Now the Bell transmitter working on the principle of which Bell is the first and undisputed inventor, is one in which the degree of contact in the circuit is never changed: for it works by the principle of “induction,” whereby currents are set up in a circuit that is never opened or closed, either partially or wholly. Nevertheless the Blake transmitter, which opens and closes the circuit in proportion to the undulations of the tympanum, is the more satisfactory instrument for producing the undulating currents required to procure the all-essential correspondence between the undulations of the tympanum of the transmitter and those of the armature of the receiver. To sum the matter up, it appears that an instrument which opens and closes the circuit on Reis’s principle of transmitting is in practice a more satisfactory transmitter of undulatory currents than Bell’s transmitter which cannot open or close the circuit in the least. Reis, with his instruments, transmitted speech--as Herr Hold tells us (p. 126)--when the words spoken were not too loud. That is a proof that he did really use, whether he knew it or not, undulatory currents of electricity: and an undulatory current is none the less an undulatory current, even if occasionally abruptly interrupted. A speech is none the less a speech, even if the orator sneeze once or twice while speaking. Nay, we may go further, and say that an undulatory current is an undulatory current, even though the finer ripples of the waves are lost in transmission. This is what seems to have been the case with Reis’s instruments as they were in 1861 and 1862. The consonants were satisfactorily transmitted, and so were all musical tones within the range of the instrument. But the finer ripples of the vowels were lost somehow in transmission. Reis, whose innate honour and modesty led him always rather to understate than overstate the facts, most frankly acknowledged this, nay even invited attention to the fact, and discussed the imperfection from a high scientific standpoint. He proposed to rely for the correctness of his views upon the actual recorded curves of sound-waves, as taken down automatically by the then newly-invented phonautograph of Scott (see p. 60). It is perfectly marvellous how precise his views were upon the correspondence between the graphic curve or wave-form of a sound and the actual sound itself; a precision amply justified by the experience and the discoveries of the last ten years.

This matter of representing sounds--or rather the varying density of the air in the sound-wave--by a graphic curve, was a vital one to Reis. Had he had a less clear view of the nature of sound-waves than that afforded by a graphic _curve_, I doubt whether he would ever have grasped the problem of the telephone--that the final vibrations, or undulations, or oscillations of the armature in the receiver must _correspond with_--must be the very counterpart of--those of the tympanum of the transmitter. The clearness with which Reis saw this is only surpassed by the clearness with which he expressed himself upon it. For him a sound was simply a complicated series of variations in the density of the air, and capable, in all its complexity, of being represented by the rise and fall of an undulatory _curve_. “Every tone, and every combination of tones, evokes in our ear vibrations ... the motions of which may be represented by a _curve_” (p. 54). “That which is perceived by the auditory nerve ... _may be represented graphically according to its duration and magnitude by a curve_” ... (p. 53). “Our ear can perceive absolutely nothing more than is capable of being represented by _similar curves_” (p. 53). The curves with which he accompanied his original memoir--and now reproduced in facsimile, from Legat’s plates, at the end of this volume--are evidence of the thoroughness of his grasp on the undulatory principle. And he explicitly states this principle amongst “the various requisite conditions which must be fulfilled by the transmitting _and receiving_ apparatus for the solution of the problem that has been set” (Legat’s Report, p. 71). He declared that so soon as it should become possible “at any place, and _in any prescribed manner_” (that is to say, whether by electric undulations or by mechanical undulations, as in the string of the toy telephone, or by any other means), “to set up vibrations whose _curves_ are like those of any given tone or combination of tones,” we should then receive the same impression as that tone or combination of tones would have produced upon us.

So much for Reis’s principle of correspondence of undulations between the transmitter and the receiver; we have seen how clear and precise, yet how comprehensive it was, and how the general proposition necessarily included within itself, as an intermediate step, the particular minor proposition that the undulations of the current must also be in correspondence with the voice.

Keeping these points in mind, it is very remarkable that when Graham Bell, fourteen years later, followed Reis “into the field of telephonic research,” he selected the very same method of expressing the relations between sounds and the undulations which corresponded with them. To show how remarkably in agreement the views of Reis and Bell are upon this question of representing by a curve the undulations which correspond to the voice, we select the following paragraphs and place them in parallel columns.

_Reis._

That which is perceived by the auditory nerve ... may be =represented graphically=, according to its duration and magnitude by a =curve=.--(Memoir ‘On Telephony’ in the Jahresbericht of the Physical Society of Frankfurt-a.-M. 1860-61, p. 59.) [p. 53.]

=The height or depth of the sound produced= ... depends upon =the number of vibrations made in a given time=.--(_Ib._ p. 63.) [p. 59.]

_Bell._

Electrical undulations, induced by a body capable of inductive action, can be =represented graphically=, without error by the same sinusoidal =curve= which expresses the vibration of the inducing body itself, and the effect of its vibration upon the air; for, as stated above, the rate of oscillation in the electrical current corresponds to the =rate of vibration= of the inducing body--that is, to =the pitch of the sound produced=.--(Specification of U. S. Patent No. 174,465, dated March 7, 1876.)

_Reis._

The greater the condensation of the sound-conducting medium at any given moment, the greater will be the =amplitude= of vibration of the membrane.--(_Ib._ p. 58.) [p. 52.]

_Bell._

The intensity of the current varies with the =amplitude= of the vibration--that is, with the loudness of the sound;--(_Ib._)

_Reis._

... each tone is dependent not only on the number of vibrations of the medium, but also on the =condensation or rarefaction= of the same.--(Legat’s Report, Zeitschrift des D.-Oesterr. Telegr. Vereins, 1863, p. 125.) [p. 77.]

_Bell._

and the polarity of the current corresponds to the direction of the vibrating body,--that is, to the =condensations and rarefactions= of air produced by the vibration.--(_Ib._)

_Reis._

Let us exhibit the condensation curves for three tones--each singly (Plate I): then, by adding together the ordinates corresponding to equal abscissæ, we can determine new ordinates and develop a new curve which we may call the =combination-curve=. Now this gives us just exactly what our ear perceives from the =three simultaneous tones=.--(Memoir ‘On Telephony,’ p. 59.) [p. 54.]

_Bell._

The combined effect of A and B, when induced simultaneously on the same circuit, is expressed by the curve A + B, Fig. 4, which is the algebraical sum of the sinusoidal curves A and B. This curve A + B also indicates the actual motion of the air when =two musical notes= considered are sounded =simultaneously=.... (_Ib._) The electrical movement, like the aerial motion, can be represented by a sinusoidal curve, or by the =resultant of several= sinusoidal =curves=.--(_Ib._)

The very remarkable agreement of the preceding passages receives a most striking confirmation by comparing the curves respectively drawn by Reis and by Bell. These are facsimiled below, Reis’s “combination”-curve (Fig. 47) from Plate I. of his Memoir (also Plate I. of this volume), and Bell’s “resultant”-curve (Fig. 48) from Fig. 4 of his United States Patent Specification No. 174,465.

The most casual observer cannot fail to notice here that the three lines of undulatory curves of Bell’s specification are practically identical with the three lower lines of undulatory curves of Reis’s memoir. They are, moreover, in each case introduced for the sake of showing how a complex curve corresponds to a compound undulation.

_Reis._.

_Bell._.

Far be it from me even to hint that either curve was plagiarised from the other. Bell tells us that his curve is to represent electrical oscillations, which, he adds, have the same curve as that both of the vibrating body and of the air. Reis tells us that his curve is to represent the oscillations of a tympanum, or of the air, or of the magnetisation of the magnet, or of the armature at the receiving end. How the magnetization of the electro-magnet was made to vary “correspondingly with the condensations and rarefactions of the air,” as represented by such a curve, Reis did not explicitly say, but left to the common sense of his readers to infer. Though the inference was obvious, Bell, who possibly had not then read Reis’s researches, seized upon this intermediate stage of the process employed by Reis, and probably quite unconscious that Reis had already employed it, announced it as a discovery of his own; and then, losing sight of the point that all that was wanted was to secure correspondence between the initial and final stage, he magnified to an absurd and unwarranted importance this intermediate correspondence of the vibrations of the current with those of the tympanum, which correspondence any one reading Reis’s papers would know at once Reis had implicitly assumed and actually employed when he transmitted articulate speech.

If we pass from the method of graphically representing undulations by curves, and proceed to compare the language in which Reis described the action of his machine in reproducing the undulations imparted to the transmitter, with that in which Graham Bell described the action of his machine some fourteen years later, we shall find[53] an agreement even more precise.

_Reis._

The =electromagnet= ... will be demagnetised and magnetised correspondingly with the condensations and rarefactions of the mass of air, ... and =the armature ... will be set into vibrations= similar to those of the =membrane= in the transmitting apparatus.--(Legat’s Report, Zeitschrift, p. 128, 1862.) [p. 77.]

_Bell._

The current traversing the coils of the =electromagnet E=, occasions an increase and diminution in its intensity, and =the armature A^1 is thrown into vibrations= ... and thus imparts to the air at _n^1_ a =facsimile= copy of the motion of the air that acted upon the =membrane= _n_.--(Specification of British Patent, No. 4765, Dec. 9th, 1876, p. 17.)

_Reis._

The transmitter, Fig. A, consists of a =conical tube= ... closed by a =membrane= ... by speaking ... into the tube ... there will be evoked a motion of the =membrane= ... (_op. cit._)

_Bell._

A =cone A= is used to converge sound vibrations upon the =membrane=.

When a sound is uttered in the cone the =membrane= _a_ is set in vibration....

_Reis._

The apparatus ... offers the possibility of =creating these vibrations= in every fashion that may be desired, and the employment of electro-galvanism gives us the possibility of calling into life, at any given distance, =vibrations similar to the vibrations= that have been produced, and in this way to reproduce at any place the tones that have been originated at another place.--(Legat’s Report, _op. cit._)

_Bell._

... and thus electrical =undulations are created= upon the circuit E _b_ _e_ _f_ _g_.... The undulatory current passing through the electromagnet _f_ influences its armature _h_ to copy the motion of the armature _c_.... These =undulations are similar in form to the air undulations caused by the sound=.

_Reis._ As soon therefore as it shall be possible ... to set up vibrations whose =curves are like= those of any given tone or combination of tones, we shall receive the same impression as that tone or combination of tones would have produced upon us.--(Memoir ‘On Telephony,’ p. 60.) [p. 55.]

_Bell._

--that is, they are represented graphically by =similar curves=....

A similar sound to that uttered into A is then heard to proceed from I.--(Specification of U. S. Patent, No. 174,465.)

_Reis._

=Any sound will be reproduced=, if strong enough to set the membrane in motion.--(Letter to Mr. Ladd, 1863.) [p. 84.]

_Bell._

There are many other uses to which these instruments may be put, such as ... the telegraphic transmission of noises or =sounds of any kind=.--(_Ib._)

I would have it understood that what I claim is:--... Tenth. In a system of electric telegraph or telephony consisting of transmitting and receiving instruments united upon an electric circuit, I claim the production in the armature of each receiving instrument of any given motion by subjecting said armature to an attraction varying in intensity, however such variation may be produced in the magnet, and hence =I claim the production of any given sound or sounds from the armature of the receiving instrument= by subjecting said armature to an attraction varying in intensity in such manner =as to throw the armature into that form of vibration that characterizes the given sound= or sounds.--(Specification of British Patent, No. 4765, Dec. 9, 1876.)

_Reis._ =the armature= belonging to the magnet =will be set into vibrations similar to those of the membrane in the transmitting apparatus=.--(Legat’s Report, 1862.) [p. 77.]

One cannot help thinking that some claims to great inventions are just a little “too previous.”

If it should still be said that Reis’s method of transmitting speech, whether it did its work by undulatory currents or no, was avowedly _imperfect_, and that therefore such a claim as that quoted above is justified by the subsequent invention of an instrument the articulation of which was more reliable, let us compare what each inventor has said about the imperfections[54] of his own instrument.

_Reis._

That which has here been spoken of will still require considerable improvement, and in particular mechanical science must complete the apparatus to be used.--(Legat’s Report, 1862.) [p. 78.]

_Bell._

It is a mistake, however, to suppose that the articulation was by any means perfect.... Still the articulation was there, and I recognized the fact that the indistinctness was entirely due to the imperfection of the instrument.--(‘Researches in Telephony,’ Journal of Soc. of Telegr. Engineers, Dec. 1877.)

If it should be said that Bell is here speaking only of an early and experimental form, and not of his real invention, it should be remembered that Bell here refers to the apparatus with cone and membrane, identical with that exhibited at Glasgow in September, 1876, by Sir William Thomson (who had received it from Bell) and by him described as the very “hardihood of invention,” and “by far the greatest of all the marvels of the electric telegraph.” It certainly worked upon the principle of undulatory currents,[55] whether it articulated or not. Bell had himself, speaking in May 1876, before the American Academy of Arts and Sciences upon his researches, even more explicitly admitted the imperfections of his own instrument.

The effects were not sufficiently distinct to admit of sustain ed conversation through the wire. Indeed, as a general rule, =the articulation was unintelligible=, excepting when familiar sentences were employed.--(Proceedings of American Academy of Arts and Sciences, vol. xii. p. 7.)

Yet this most imperfect machine, of which the articulation was, as a general rule, unintelligible, had, two months previously, had a patent granted to it as a new invention, the claim being for “the method of, and apparatus for, transmitting vocal or other sounds telegraphically, as herein described, by causing electrical undulations similar in form to the vibrations of the air accompanying the said vocal or other sounds, substantially as set forth.”

If then mere mechanical imperfections do not make an invention any the less a true invention capable of legal recognition, it would be dishonest to the last degree to deny to Philipp Reis the honour of his invention, of which he honestly and openly stated both the successes and the imperfections. He told the world what he aimed at, and in what measure success had crowned his aims. His claim to be the inventor of the Telephone he considered to be justified by that measure of success. If he was so far in advance of his time that the world was unprepared to receive or use the splendid discovery which he gave freely to it, that was not his fault; nor does neglect or apathy make him in one single degree the less entitled to the credit of his inventions. _Tulit alter honores_ has not unfrequently been truly said concerning the men of genius who have had the misfortune to live in advance of the age.

But posterity does not let the names of such truly great ones perish in the dust. The inventor of the Telephone will be remembered and honoured in the coming if not in the present age.

SCHEDULE OF AUTHORITIES

Key to Title of Work:

A. ‘Jahresbericht des Physikalischen Vereins zu Frankfurt-am-Main’ B. ‘Fortschritte der Physik’ (Krönig and Beetz) C. Dingler’s ‘Polytechnisches Journal’ D. ‘Polytechnisches Central-Blatt’(Schnedermann and Böttcher) E. Böttger’s ‘Polytechnisches Notizblatt’ F. ‘Didaskalia’ G. ‘Zeitschrift des Deutsch-Oesterreichischen Telegraphen Vereins’ (Dr. Brix) H. Kuhn’s ‘Handbuch der angewandten Elektricitätslehre’ I. Pisko’s ‘Die Neueren Apparate der Akustik’ J. (Pisko’s) ‘Hessler’s Lehrbuch der Technischen Physik’ K. Müller Pouillet’s ‘Lehrbuch der Physik’

+----------+------------+--------+---------------------+-------------+ | Title | Place of | Date. | Volume and | British | | of Work. | Issue. | | Page. | Museum. | +----------+------------+--------+---------------------+-------------+ | A. | Frankfurt |{1860-1 | p. 57 }| Ac. 4428 | | | -a.-M. |{1863 | p. 129 }| | | | | | | | | B. | Berlin |{1861 | xvii. p. 171-173 }| Ac. 3775 | | | |{1863 | ----? p. 96 }| | | | | | | | | C. | Stuttgart | 1863 |{clxviii. p. 185-187}| Pp. 1780 | | | | |{clxix. p. 23 }| | | | | |{clxix. p. 399 }| | | | | | | | | D. | Cassel | 1863 | xxix. p. 858 | Pp. 1615 b. | | | | | | | | E. | Mainz | 1863 |{No. 6 }| Pp. 1787 | | | | |{No. 15 }| | | | | | | | | F. | Frankfurt | 1862 | May 8, May 14 | .. | | | -a.-M. | | | | | | | | | | | G. | Berlin | 1862 | ix. p. 125 | .. | | | | | | | | | | | | | | H. | Leipzig | 1866 | p. 1017-1021 | 2244 i | | | | | | | | I. | Vienna | 1865 |{p. 94-103 }| 8705 cc. | | | | |{p. 241-243 }| | | | | | | | | J. | Vienna | 1866 | Vol. I. p. 648 | .. | | | | | | | | K. | Brunswick | 1868 | Vol. II. p. 386-388 | .. | | | | | | | +----------+------------+--------+---------------------+-------------+

AND REFERENCES.

Key to references: 1. Royal Society. 2. Ronald’s Library. 3. Institution Civil Engineers. 4. Royal Institution. 5. Great Seal Patent Office. 6. School of Mines. 7. University College, London. 8. Bodleian Library, Oxford. 9. King’s College. 10. Oxford University Museum Library.

+---------+-----+---+---+-------+------+---+-----+---------+---+---+ | Title | 1. | 2.| 3.| 4. | 5. | 6.| 7. | 8. | 9.|10.| | of Work.| | | | | | | | | | | +---------+-----+---+---+-------+------+---+-----+---------+---+---+ | A. |1846 | ..| ..| .. | .. | ..| .. | .. | ..| ..| | |-1860| | | | | | | | | | | | | | | | | | | | | | | B. | x | ..| x | x |6546, | x | x | .. | x | x | | | | | | |118 E | | | | | | | | | | | | | | | | | | | C. | x | ..| x | x |1296, | x | .. | .. | ..| ..| | | | | | | 94 A | | | | | | | | | | | | | | | | | | | D. | .. | ..| ..| .. |1132, | ..| .. | .. | ..| ..| | | | | | | 94 I | | | | | | | | | | | | | | | | | | | E. | .. | ..| ..| .. | .. | ..| .. | .. | ..| ..| | | | | | | | | | | | | | F. | .. | ..| ..| .. | .. | ..| .. | .. | ..| ..| | | | | | | | | | | | | | G. | .. | ..| x | .. |9511, | ..| .. | .. | ..| ..| | | | | | | 24 E | | | | | | | | | | | | | | | | | | | H. | .. | x | ..| x |13146,| ..| .. |198 e 133| ..| ..| | | | | | |163 C | | | | | | | | | | | | | | | | | | | I. | x | ..| ..| .. | .. | ..| .. | .. | ..| x | | | | | | | | | | | | | | J. | .. | x | ..| .. | .. | ..| .. | .. | ..| ..| | | | | | | | | | | | | | I. | .. | ..| ..|A newer| .. | x |(Ed. | .. | ..| x | | | | | |edition| | |1876)| | | | | | | | |(1872) | | | | | | | +---------+-----+---+---+-------+------+---+-----+---------+---+---+

FOOTNOTES:

[53] In making these comparisons in parallel columns, I wish to repudiate in the most emphatic way any sinister inference that might be drawn as to Graham Bell’s use of descriptions and curves identical in so many points with those of Reis. For, in the first place, I believe Professor Bell to be incapable of such contemptible appropriations, and the candour with which he has himself invited comparison by giving various references to Reis’s papers, itself precludes such inference. In the second place, I do not think that at the date of these quotations Bell understood German sufficiently well to comprehend Reis’s very precise statement of the problem of the Telephone. I simply exhibit these parallel extracts to show the thoroughness with which Reis had grappled with the problem with which, fourteen years later, Bell also grappled; and to prove in the most irrefragable manner, from the necessary identity in the terms selected for expressing the facts of the solution of the problem, that the problem to which each found a solution was identical. The circumstance that does, however, puzzle me, and which does not appear in these parallel extracts, is that, whilst in his original memoir, Reis speaks in detail of the auditory ossicles and their movements as having suggested his transmitter, and casually mentions the phonautograph of Scott in support of his views, Bell, in his original lecture before the American Academy, speaks in detail of Scott’s phonautograph as having suggested his transmitter, and casually refers to the auditory ossicles and their movements.

[54] Reis’s failures were chiefly with the vowels, Bell’s more particularly with the consonants. Reis’s contacts were liable to break, and the following-springs of his contact-regulators too little pliable. Bell’s transmitter could not open and close the circuit proportionally with the motions of the tympanum, and owing to the sluggishness due to self-induction in the coils of his telephone, the induced undulations of the current failed to come up in suddenness to those of the tympanum. In consequence _whip_ sounded like _whim_, and _kiss_ like _kith_, even in the perfected Bell Telephones made two years after Bell’s first “improvements” in telephony were patented.

[55] The following very remarkable passage occurs in the evidence given by Professor Graham Bell concerning Reis’s Telephones. (See published volume of ‘Proceedings in the United States Patent Office before the Commissioner of Patents.’ _Evidence for A. G. Bell_, p. 14.)

_Question 37._ “If a Reis Telephone, made in accordance with the descriptions published before the earliest dates of your invention, would in use transmit and receive articulate speech as perfectly as the instruments did which were used by you on June 25, 1876, at the Centennial, would it be proof to you that such Reis’s Telephones operated by the use of undulatory movements of electricity in substantially the same way as your instruments did upon the occasion referred to?”

_Answer by Bell._ “The supposition contained in the question cannot be supposed. Were the question put that if I were to hear an instrument give forth articulate speech transmitted electrically as perfectly as my instruments did on the occasion referred to in the question, I would hold this as proof that the instrument had been operated by undulatory movements of electricity, I would unhesitatingly answer, Yes.”

Surely no better authority is needed to support the proposition that if Reis made his Telephone speak, as he said he did, he employed undulatory currents.

ADDITIONAL PREFERENCES CONCERNING REIS’S TELEPHONE.

Schenk’s _Philipp Reis, der Erfinder des Telephons_, 1878.

Sack’s _Die Entwickelung der elektrischen Telephonie_, 1878.

Ferguson’s _Electricity_ (Ed. 1867), p. 257.

Wiedemann’s _Galvanismus_ (1874), Vol. ii. p. 598.

_Gartenlaube, die_; for 1863, No. 51, p. 807-809.

_Aus der Natur_; for 1862, xxi. p. 470-474.

_Cosmos_, Vol. xxiv. p. 349 (1864).

_Proc. Lit. Phil. Soc. Manchester_ (1865), Nov. 10, 1864.

_Rep. Brit. Assoc_. (1863), p. 19.

_Die Geschichte und Entwickelung des elektrischen Fernsprechwesens_, 1880. (Officially issued from the Imperial German Post-Office, Berlin.)

LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET AND CHARING CROSS.

Plate 1.

THO^s. KELL & SON. LITH 40, KING S^t. COVENT GARDEN #/

REPRODUCTION OF TONES IN THE ELECTRO-GALVANIC WAY.

THO^s. KELL & SON. LITH 40, KING S^t. COVENT GARDEN #/

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_A Pocket-Book for Chemists, Chemical Manufacturers, Metallurgists, Dyers, Distillers, Brewers, Sugar Refiners, Photographers, Students, etc., etc._ By Thomas Bayley, Assoc. R.C. Sc. Ireland, Analytical and Consulting Chemist and Assayer. Second edition, with additions, 437 pp., royal 32mo, roan, gilt edges, 5_s_.

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_The Mechanician_: A Treatise on the Construction and Manipulation of Tools, for the use and instruction of Young Engineers and Scientific Amateurs, comprising the Arts of Blacksmithing and Forging; the Construction and Manufacture of Hand Tools, and the various Methods of Using and Grinding them; the Construction of Machine Tools, and how to work them; Machine Fitting and Erection; description of Hand and Machine Processes; Turning and Screw Cutting; principles of Constructing and details of Making and Erecting Steam Engines, and the various details of setting out work, etc., etc. By Cameron Knight, Engineer. _Containing_ 1147 _illustrations_, and 397 pages of letter-press. Third edition, 4to, cloth, 18_s_.

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A complete Explanation of the London Practice. General Instructions. Order of Taking Off. Modes of Measurement of the various Trades. Use and Waste. Ventilation and Warming. Credits, with various Examples of Treatment. Abbreviations. Squaring the Dimensions. Abstracting, with Examples in illustration of each Trade. Billing. Examples of Preambles to each Trade. Form for a Bill of Quantities. Do. Bill of Credits. Do. Bill for Alternative Estimate. Restorations and Repairs, and Form of Bill. Variations before Acceptance of Tender. Errors in a Builder’s Estimate. Schedule of Prices. Form of Schedule of Prices. Analysis of Schedule of Prices. Adjustment of Accounts. Form of a Bill of Variations. Remarks on Specifications. Prices and Valuation of Work, with Examples and Remarks upon each Trade. The Law as it affects Quantity Surveyors, with Law Reports. Taking Off after the Old Method. Northern Practice. The General Statement of the Methods recommended by the Manchester Society of Architects for taking Quantities. Examples of Collections. Examples of “Taking Off” in each Trade. Remarks on the Past and Present Methods of Estimating.

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