cm. An inclined mouthpiece of tin with funnel-shaped opening serves

to receive the tones. The longer side of this mouthpiece measures 6·7 cm., the shorter 4·7 cm.; the longer diameter of the widening measures 7·15 cm., the shorter diameter 7·5 cm., and finally the diameter of the narrow tube 3·9 cm.

It is clear that, if necessary, the platinum strip can be replaced by a strip of thin sheet-brass, the platinum or steel points by iron. Only in this case the points of contact must be oftener cleaned to a metallic polish.

(_c._) The receiver (Zeichengeber) C is in general a double resonant box, whose upper part, “the cover,” is moveable upon two hinges, and can be laid back. The length of this cover is 16·4 cm., its width 9·5 cm., and its height 3·2 cm. The length of the lower box measures 22·9 cm., its width 9·6 cm., and its height 2·5 cm. The under part of the resonant box bears two wooden bridges, which stand about 7·4 cm. from each other, and which serves as supports for the 21·5 cm. long, and 0·9 cm. thick iron needle destined for reproducing the tones. The length of spiral wound over the needle, and designed for making an electro-magnet of the same, is 15 cm. The wooden covers of both parts, scraped as thin as possible, and the greatest breadth of the circular holes shown in the figure, measures 13 mm.

(_d._) For a battery one can successfully use a small Smee’s consisting of four elements, or two larger Bunsen’s cells.

The conductor must be at least sufficiently long that one cannot perceive the tones that are produced. For correspondence between the two stations the inventor has employed the electro-magnetic telegraph arrangement, _e v g h_, seen in the mechanism, and easily understood. An agreement in reference to corresponding signs can be easily arranged, and the simplest way is to accept the signals arranged by the inventor. (See ‘Prospectus.’)

The receiver C gives, when the key _e_ is pressed, the corresponding telegraphic signals by means of tones in the rod E E, while at the transmitter, A, the electro-magnet _v_ gives the signals by means of the springy armature _z_.

[53.] Experiments with the Telephone.

(_a._) As soon as one brings the mouth to the funnel S and sings, the membrane of the transmitter, A, vibrates in a corresponding manner, and the iron rod, E E, at the second station begins to give forth a tone. Every time a spark is seen at the first station _s_, the rod at the other station certainly gives forth a tone. The same is true when one hears the peculiarly snarling tone which arises from the stroke of the vibrating platinum strip against the spike of angular hook resting upon it.

The appearance of these sparks or of the peculiar snarling at the transmitter A gives the sign to the observers at the station A that the rod in C is giving a tone. Tones and melodies which were sung into the sound aperture, and especially sounds in which the teeth and bones of the head also vibrated (so-called humming tones), always evoked a tone in the rod or needle E E, and indeed, as already mentioned (§ 51), without change in the pitch, but only with the reproduction of the rhythm of the respective song or words.

The pitch of the tone excited at C in the rod E E was in the apparatus at my disposal _h_; its strength not very great and its clang snarly, similar to that of a lightly sounding reed-whistle, somewhat like that of a child’s wooden trumpet. The cuticle lying about the heart of the smaller and even the larger mammals (from calves, &c.) makes the best membranes. Goldbeater’s-skins reproduce only the deeper tones. The cover of the sounding-box appeared in my apparatus superfluous, and indeed the tone was somewhat stronger without the cover.

1. In experiments with the telephone, one must look closely as to whether the ends of the platinum strip is still fastened to the membrane, and one must, if necessary, press upon the membrane. If the strip will no longer stick, heat a knife-blade, touch a small piece of sealing wax with it, and carry thus the melted sealing-wax to the under side of the round end of the platinum-strip, _n s_. Then press it immediately on the membrane, _m m_.

Ph. Reis showed his apparatus in very primitive form for the first time in October, 1861, to the Physical Society at Frankfort-on-the-Main; on July 4th, 1863, before the same society, he showed the form represented in Fig. 33. This time he experimented upon a distance of 300 feet. Professor Boettger brought the apparatus before the Naturforscher-Versammlung at Stettin (1863) in the section for Physics.

[=16.=] HESSLER’S ‘TEXT-BOOK OF TECHNICAL PHYSICS,’ vol. i. p. 648.

[Next in chronological order comes a notice of the Telephone in Hessler’s ‘Lehrbuch der technischen Physik,’ edited by Prof. Pisko, and published at Vienna in 1866. The brief account given in this work adds nothing to the accounts previously given, and is evidently written by some person ignorant of Reis’s own work, for beside omitting all mention of the transmission of speech by the instrument, or of its being constructed upon the model of the human ear, the writer appears not even to know how to spell Reis’s name,[37] and speaks of him as “Reuss.”]

[=17.=] KUHN’S ‘HANDBOOK OF APPLIED ELECTRICITY,’

(‘Handbuch der Angewandten Elektricitätslehre,’ von Carl Kuhn), being vol. xx. of Karsten’s ‘Universal Encyclopædia of Physics’ (Karsten’s ‘Allgemeine Encyclopädie der Physik’).

[Karsten’s ‘Encyclopædia of Physics,’ which has been for many years a standard work of reference, both in Germany and in this country, consists of a number of volumes, each of which is a complete treatise, written by the very highest authorities in Germany. Thus Helmholtz contributed the volume on Physiological Optics, Lamont that on Terrestrial Magnetism, whilst the names of Dr. Brix, Professor von Feilitzsch, and others, are included amongst the authors. Carl Kuhn, who wrote vol. xx., was Professor in the Royal Lyceum of Munich, and member of the Munich Academy. Kuhn’s volume on ‘Applied Electricity,’ published in 1866, is to be found on the shelves of almost every library of any pretensions in Great Britain. The account given therein of Reis’s Telephone is interesting, because it describes two forms, both of transmitter and of receiver. In fact the descriptions and figures are taken almost directly from von Legat’s Report (p. 70), and from Reis’s Prospectus (p. 87). The extract translated below includes all the matter that is of importance.]

P. 1017. The researches established by Reis on the 26th of October, 1861, in Frankfurt[38] have already shown that if the current interruptions follow one another almost continuously and very rapidly, in a spiral arranged with a thin iron core, the iron wire can be set into longitudinal vibrations, whereby therefore the same is constrained to reproduce tones of different pitch.

* * * * *

[Here follows a reference to Petrina’s Electric Harmonica.]

* * * * *

From the communications made known by Legat, it follows that “the ideas concerning the reproduction of tones by means of electro-galvanism which were put forward some time since by Philipp Reis of Friedrichsdorf, before the Physical Society, and the meeting of the Free German Institute in Frankfort-on-the-Main,” relate to similar arrangements. “What has hitherto been attained in the realisation of this project,” Legat announces in his report, and we extract therefrom only that part which gives an explanation of the disposition of the telegraphic apparatus, with which it is said to be possible to produce the vibrations and the excitement of tones in any desired manner, and by which the employment of electro-galvanism is said to make it possible “to call 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.”

This apparatus consists of the tone-indicator (transmetteur) and the tone-receiver (récepteur). The tone-indicator (Fig. 34, p. 109) consists of a conical tube, _a b_, having a length of about 15 cm., a front aperture of about 10 cm., and a back aperture of about 4 cm., the choice of the material and the greater length of which is said to be indifferent, while a greater width is said to be injurious; the surface of the inner wall should be as smooth as possible. The narrow back aperture of the tube is closed by a membrane, _o_, of collodion, and upon the centre of the circular surface formed by this membrane rests the one end, _c_, of the lever, _c d_, the supporting-point of which, _e_, being held by a support, remains in connection with the metallic circuit. This lever, the arm, _c e_, of which must be considerably longer than _c d_, should be as light as possible, so that it can easily follow the movements of the membrane, because an uncertain following of the lever, _c d_, will produce impure tones at the receiving station. During the state of rest the contact, _d g_, is closed, and a weak spring, _n_, keeps the lever in this state of rest. Upon the metallic support, _f_, which is in connection with one pole of the battery, there is a spring, _g_, with a contact corresponding to the contact of the lever, _c d_, at _d_, the position of which is regulated by means of the screw, _h_. In order that the effect of the apparatus may not be weakened by the produced waves of air communicating themselves towards the back part, a disc “of about 50 (?) cm. diameter, which rests fixedly upon the exterior wall of the tube,” is to be placed above the tube, _a b_, at right angles with its longitudinal axis.

The tone-receiver consists of an electro-magnet, _m m_, which rests upon a resounding-board, _u w_, and the surrounding coils of which are connected with the metallic circuit and the earth. Opposite to the electro-magnet there stands an armature, which is connected with a lever, _i_, as long as possible but light and broad, and which lever together with the armature, is fastened like a pendulum to the support _k_; its movements are regulated by the screw _l_ and the spring _q_. “In order to increase the effect of the apparatus, this tone-receiver may be placed in the one focus of an elliptically hollowed cavity of sufficient size, while the ear of the person who listens to the reproduced sounds ought to be placed at the second focus of the cavity.” The action of the two apparatus, the general manner of connection of which may be seen from the illustrations--at the one station being the tone-indicator, at the other the tone-receiver--is the following:--By speaking into, singing, or conducting the tones of an instrument into the tube, _a b_, there is produced in the tone-indicator (Fig. 34) in consequence of the condensation and rarefaction of the enclosed column of air, a motion of the membrane, _c_, corresponding to these changes. The lever, _c d_, follows the movements of the membrane, and opens or closes the circuit according as there occurs a condensation or rarefaction of the enclosed air. In consequence of these actions, the electro-magnet, _m m_ (Fig. 13), is correspondingly demagnetised or magnetised, and the armature (and the armature-lever) belonging to it is set into vibrations similar to those of the membrane of the transmitting apparatus. By means of the lever, _i_, connected with the armature, the similar vibrations are transmitted to the surrounding air, and these sounds thus produced finally reach the ear of the listener (the sounding-board increasing the effect). As regards the effectiveness of this apparatus, the author remarks that while the similar number of the produced vibrations is reproduced by the receiver, their original strength has not yet been obtained by it. For this reason also small differences of vibration are difficult to hear, and during the practical experiments hitherto made, chords, melodies, &c., could be, it is true, transmitted with astonishing (?) fidelity, while single words in reading, speaking, &c., were less distinctly perceived.

* * * * *

[The rest of the article deals with the “square-box” transmitter described in Reis’s Prospectus, and adds nothing to the information already published.]

[This is the last of the contemporary documents bearing upon the performance of Reis’s instruments. From the prominent notice obtained at the time by the inventor, it is clear that his invention was even then accorded an honourable place amongst the acknowledged conquests of science. A critical examination of this body of evidence proves not only the substantial nature of Reis’s claim, but that the claim was openly recognised and allowed by the best authorities of the time. The thing was not done in a corner.]

FOOTNOTES:

[15] [This was the number formerly accepted on the authority of Despretz as the minimum number of vibrations that could evoke the sensation of a tone in the human ear. The limit now more usually recognized is that of Helmholtz, who assigns from thirty to forty double vibrations per second as the minimum.]--S. P. T.

[16] [The three plates or tables with which Reis accompanied his Memoir, containing a variety of undulatory curves corresponding to various combinations of tones, both of musical concords and of dissonant sounds, are not reprinted in this book in their entirety. Table I. contained three sets, the first of which is reproduced by photo-lithography in reduced facsimile in Fig. 47, p. 173. It was also reproduced by W. von Legat in his Report from which Plate I. at end of this book is copied, Fig. 1 of that plate being the same as Fig. 1 of Reis’s Table I. Fig. 2 of Plate 1, was in like manner copied by Legat from the first figure of Reis’s Table II., and Fig. 3 of Plate I., which represents the curves of a non-harmonious combination is the same as Reis’s Table III., the only difference being that in Reis’s Table III. the irregular undulations of the resultant curve were emphasised by being labelled ‘Dissonanz.’]--S. P. T.

[17] [This is true for speech-tones as well as for musical tones. Each kind of tone may be represented by its own characteristic curve.]--S. P. T.

[18] [This is the fundamental principle, not only of the telephone, but of the phonograph; and it is wonderful with what clearness Reis had grasped his principle in 1861.]--S. P. T.

[19] [That is, at any single demagnetisation of the needle, it vibrates and emits the same tone as if it had been struck or mechanically caused to vibrate longitudinally.]--S. P. T.

[20] [This range was simply due to the degree of tension of the tympanum; another tympanum differently stretched, or of different proportions, would have a different range according to circumstances.]--S. P. T.

[21] [The so-called “galvanic tone” heard on opening or closing the circuit _was_ well-known, and Wertheim had shown that this tone was, for any given rod of iron, identical with its “longitudinal tone,” _i.e._ the tone produced by striking it on the end so as to produce longitudinal vibrations. But it was one of the most important discoveries in Reis’s researches that such a rod could take up _any_ tone in obedience to the vibrations forced upon it by periodic interruptions in the magnetising current in the spiral of any degree of rapidity within very wide limits. The translator has had occasion to examine this point, and has found iron, steel, and cobalt wires varying from 4 to 10 inches in length, including some used by Reis himself as receivers, to be capable of taking up vibrations from as slow as 40 per second to the very shrillest whistle audible to human ears, or exceeding 36,000 per second. It is sometimes also mistakenly supposed that such a wire can respond only to the vibrations of tones that are musical, not to those that are articulate, including both consonants and vowels. This, however, is an entire mistake. For, using such a wire as a receiver (surrounded by its proper coil and mounted with an appropriate sounding board, or, better still, tympanum), in conjunction with a well-adjusted transmitter, the articulation transmitted surpasses that obtainable with any of the ordinary magnetic receivers in distinctness, though not in loudness. This discovery of Reis’s is of the greatest importance, especially as some who ought to know better have very unjustly denied the capability of this part of the apparatus to act as a telephone receiver for articulate sounds.]--S. P. T.

[22] [This limit is a mistake of Professor Böttger’s. The longitudinal tone of an unstrained iron or steel wire 10 inches long would be a note about four octaves above the middle _c_ of the piano; whereas, in fact, any note of the whole piano-gamut down to the lowest note, can be reproduced by such a wire, as stated in preceding footnote.]--S. P. T.

[23] [Professor Böttger had not to wait long for the fulfilment to a very large degree of this anticipation; for within six months Dingler’s Journal, in which this article appeared, contained Legat’s report on Reis’s instruments, in which not only were various modifications in their construction made known, but also the transmission of voice-tones, not yet perfectly but with recognisable modulations and intonations, was recorded. Reis had, indeed, succeeded nearly as well as this with his first instrument, as his memoir of 1861 shows. See p. 58.]

[24] [Compare ‘_Die Geschichte und Entwickelung des Fernsprechwesens_,’ a pamphlet issued officially in 1880 from the Imperial German Post-Office in Berlin, p. 6.]

[25] [Plate VIII. of the original in Vol. IX. of the Zeitschrift.]

[26] [Plate IX. of the original Memoir.]

[27] [This word, as the context and ending of the paragraph shows, should have been spelled _tones_. The letter, written in English by Reis himself, is wonderfully free from inaccuracies of composition; the slip here noted being a most pardonable one since the plural of the German “_ton_” is “_tönen_,” the very pronunciation of which would account for the confusion in the mind of one unaccustomed to write in English. So far as is known, this is the only piece of English composition ever attempted by Reis.--S. P. T.]

[28] [Reis here sketched a figure identical in all its parts with that which a fortnight later was issued in his ‘Prospectus.’ His sketch is reproduced in facsimile in Fig. 28.]

[29] [This was the little auxiliary signalling apparatus at the side of the box, placed there for the same reasons as the auxiliary call-bell attached to modern telephones.]

[30] [This word is underscored in Reis’s original letter.]

[31] [Compare Böttger Polyt. Notizbl. 1863, p. 81, the notice translated at p. 61 preceding.]--S. P. T.

[32] [This rather obscure passage refers to the call-key or communicator fixed to the side of the instruments, and which as the inventor explains in his Prospectus (see p. 87), to be intended, like the call-bell or communicator of modern telephones, as a means of sending signals to the speaker, and which, as the Prospectus says, can also be used--as any call-bell can--for telegraphing words by a pre-arranged code of signals.]--S. P. T.

[33] [Fig. 30 of this book.]

[34] [References.] _Telephon von Reis_ im Jahresbericht des physikalischen Vereins zu Frankfurt-a.-M. für 1860-1861, pag. 57 bis 64. _Müller-Pouillet_, Physik, 1863, 6. Auflage, II pag. 352, Fig. 325. _Berl. Ber._ für 1861, xvii. pag. 171 bis 173. Der Musiktelegraph in der “Gartenlaube” 1863, Nr. 51, pag. 807 bis 909. Aus der Natur 1862, xxi. pag. 470 bis 484; _König’s_ Catalog, 1865, pag. 5.

[35] [This part of the apparatus is in fact a “call,” serving precisely the same function as the call-bell attached to ordinary telephones, by which the subscriber can be “called up” to listen to the instrument. It is not without importance to observe that this function was perfectly well-known at the time; for it was gravely argued during a former telephone law-suit in England that the presence of this “signal-call” at the side of the Reis Transmitter was a proof that it was intended to transmit singing only _and not speech_, or “else there would not have been that little Morse-instrument at the side by which to talk”! This suggestion is, however, self-evidently absurd, because if this had been the case the little electromagnetic Morse telegraph would have been fixed, not on the side of the transmitter but on that of the receiver. Reis himself explains the use of the “call” (see p. 87) in his “Prospectus.”]--S. P. T.

[36] [Professor Pisko seems to have got hold of an unusually unfortunate specimen of the instrument if he could make it neither speak nor sing. His transmitter must have been in exceedingly bad condition to fail so completely.]

[37] This error has been copied by Count du Moncel, along with the other defects of the article, into the fifth volume of his ‘Applications of Electricity,’ published in 1878. It is rather amusing now to read, at p. 106, of Du Moncel’s treatise that “Heisler” (_sic_) “pretends” that the telephone of “Reuss,” which “appears” to have been invented “anterior to the year 1866,” was capable of transmitting vocal melodies! Count du Moncel, though he has since posed as an authority on the telephone, did not in 1878 shine in that capacity, for on the very same page of the Count’s book may be found the following astounding sentiment:--“_If it is true_, as Sir W. Thomson has assured us, _that at the Philadelphia Exhibition of 1876 there was a telegraphic system transmitting words_, we may recognize,” &c. Count du Moncel has since found out that it _is_ true that there was a Telephone in Philadelphia in 1876: perhaps he will next discover that “Reuss” did, “anterior to the year 1866,” actually “appear” to transmit not only what “Heisler” “pretends” he did, but that he also transmitted spoken words.--S. P. T.

[38] Ueber Fortpflanzung der Töne auf wilkührlich weite Entfernungen, mit Hülfe der Elektricität (Telephonie). Polyt. Journ. clxviii. 185; aus Böttger’s Notizbl. 1863, Nr. 6. [See translation on page 61.]