CHAPTER II.

THE INVENTOR’S APPARATUS.

In describing the various forms successively given by the inventor to his apparatus, as he progressed, from the earliest to the latest, it will be convenient to divide them into two groups, viz. the Transmitters and the Receivers.

_A.--Reis’s Transmitters._

So far as can be learned, Reis constructed transmitters in some ten or twelve different forms. The complete series in this course of evolution does not now exist, but the principal forms still remain and will be described in their historical order. Theoretically, the last was no more perfect than the first, and they all embody the same fundamental idea: they only differ in the mechanical means of carrying out to a greater or less degree of perfection the one common principle of imitating the mechanism of the human ear, and applying that mechanism to affect or control a current of electricity by varying the degree of contact at a loose joint in the circuit.

_First Form._--THE MODEL EAR.

Naturally enough the inventor of the Telephone began with crude and primitive[3] apparatus. The earliest form of telephone-transmitter now extant, was a rough model of the human ear carved in oak wood, and of the natural size, as shown in Figs. 2, 3, 4, & 5.

The end of the aperture _a_ was closed by a thin membrane _b_, in imitation of the human tympanum. Against the centre of the tympanum rested the lower end of a little curved lever _c d_, of platinum wire, which represented the “hammer” bone of the human ear. This curved lever was attached to the membrane by a minute drop of sealing-wax, so that it followed every motion of the same. It was pivoted near its centre by being soldered to a short cross-wire which served as an axis; this axis passing on either side through a hole in a bent strip of tin-plate screwed to the back of the wooden ear. The upper end of the curved lever rested in loose contact against the upper end _g_ of a vertical spring, about one inch long, also of tin-plate, bearing at its summit a slender and resilient strip of platinum foil. An adjusting-screw, _h_, served to regulate the degree of contact between the vertical spring and the curved lever. The conducting-wires by which the current of electricity entered and left the apparatus were connected to the screws by which the two strips of tin-plate were fixed to the ear. In order to make sure that the current from the upper support of tin should reach the curved lever, another strip of platinum foil was soldered on the side of the former, and rested lightly against the end of the wire-axis, as shown in magnified detail in Fig. 6. If now any words or sounds of any kind were uttered in front of the ear the membrane was thereby set into vibrations, as in the human ear. The little curved lever took up these motions precisely as the “hammer”-bone of the human ear does; and, like the “hammer”-bone, transferred them to that with which it was in contact. The result was that the contact of the upper end of the lever was caused to vary. With every rarefaction of the air the membrane moved forward and the upper end of the little lever moved backward and pressed more firmly than before against the spring, making better contact and allowing a stronger current to flow. At every condensation of the air the membrane moved backwards and the upper end of the lever moved forward so as to press less strongly than before against the spring, thereby making a less complete contact than before, and by thus partially interrupting the passage of the current, caused the current to flow less freely. The sound waves which entered the ear would in this fashion throw the electric current, which flowed through the point of variable contact, into undulations in strength. It will be seen that this principle of causing the voice to control the strength of the electric current by causing it to operate upon a loose or imperfect contact, runs throughout the whole of Reis’s telephonic transmitters. In later times such pieces of mechanism for varying the strength of an electric current have been termed current-regulators.[4] It would not be inappropriate to describe the mechanism which Reis thus invented as a combination of a tympanum with an electric current-regulator, the essential principle of the electric current-regulator being the employment of a loose or imperfect contact between two parts of the conducting system, so arranged that the vibrations of the tympanum would alter the degree of contact and thereby interrupt in a corresponding degree the passage of the current.

Mr. Horkheimer, a former pupil of Reis, informs me that a much larger model of the ear was also constructed by Reis. No trace of this is, however, known.

_Second Form._--TIN TUBE.

The second form, a tube constructed by Reis himself, of tin, is still to be seen in the Physical cabinet of Garnier’s Institute, at Friedrichsdorf, and is shown in Fig. 7. It consists of an auditory tube _a_, with an embouchure representing the pinna or flap of the ear. This second apparatus shows also a great similarity with the arrangement of the ear, having the pinna or ear-flap, the auditory passage, and the drum-skin (_a_, _b_, _c_). Upon the bladder _c_ there still remains some sealing-wax, by means of which a little strip of platinum, for the all-essential loose-contact that controlled the current, had formerly been cemented to the apparatus.

_Third Form._--THE COLLAR-BOX.

The third form, also preserved in the collection in Garnier’s Institute, is given in Fig. 8, which, with the preceding, is taken by permission from the pamphlet of the late Professor Schenk, consists of a round tin box, the upper part of which fits upon the lower precisely like the lid of a collar-box. Over this lid _b_, which is 15 centimetres in diameter, was formerly stretched the vibrating membrane, there being also an inner flange of metal. Into a circular aperture below opened an auditory tube _a_, with an embouchure representing the pinna. The precise arrangements of the contact-parts of this apparatus are not known. Mr. Horkheimer, who aided Reis in his earlier experiments, has no knowledge of this form, which he thinks was made later than June 1862. This is not improbable, as the design with horizontal membrane more nearly approaches that of the tenth form, the “Square-box” pattern.

_Fourth Form._--THE BORED-BLOCK.

The instrument described by Reis in his paper “On Telephony,” in the Annual Report of the Physical Society of Frankfort-on-the-Main, for 1860-61 (see p. 50), comes next in order. The inventor’s own description of this telephone (Fig. 9) is as follows:--

“In a cube of wood, _r s t u v w x_, there is a conical hole _a_, closed at one side by the membrane _b_ (made of the lesser intestine of the pig), upon the middle of which a little strip of platinum is cemented as a conductor [or electrode]. This is united with the binding screw _p_. From the binding screw _n_ there passes likewise a thin strip of metal over the middle of the membrane, and terminates here in a little platinum wire, which stands at right-angles to the length and breadth of the strip. From the binding-screw _p_ a conducting wire leads through the battery to a distant station.” The identical apparatus used by Reis was afterwards given by him to Professor Böttger, who later gave it to Hofrath Dr. Th. Stein, of Frankfort, from whose hands it has recently passed into the possession of the author of this work. It possesses one feature not shown in the original cut, viz. an adjusting screw, _h_, which, so far as the writer can learn, was put there by Reis himself. There appears no reason to doubt this, since there was an adjusting screw in Reis’s very earliest form of transmitter, the wooden ear. A section of the actual instrument is given in Fig. 10.

_Fifth Form._--THE HOLLOW CUBE.

Another form, a mere variety of the preceding, is described as follows by Professor Böttger in his “Polytechnisches Notizblatt” (see p. 61):--

“A little light box, a sort of hollow cube of wood, has a large opening at its front side and a small one at the back of the opposite side. The latter is closed with a very fine membrane (of pig’s smaller intestine) which is strained stiff. A narrow springy strip of platinum foil, fixed at its outer part to the wood, touches the membrane at its middle; a second platinum strip is fastened by one of its ends to the wood at another spot, and bears at its other end a fine horizontal spike, which touches the other little platinum strip where it lies upon the membrane.”

_Sixth Form._--THE WOODEN CONE.

Another transmitter, also a mere variety of the Fourth Form, has been described to me by Herr Peter, of Friedrichsdorf, who assisted Reis in his earlier experiments. Fig. 11 is prepared from a rough sketch furnished me by the kindness of Karl Reis. Herr Peter describes the apparatus as having been turned out of a block of wood by Reis upon his own lathe. The conical hole was identical with that of Fig. 9, but the surrounding portions of the wood were cut away, leaving a conical mouth-piece.

_Seventh Form._--“HOCHSTIFT” FORM.

The engraving presented below (Fig. 12) has been engraved with the utmost fidelity by Mr. J. D. Cooper, from a photograph lent to the author by Ernest Horkheimer, Esq., of Manchester, a former pupil of Reis. The original photograph was taken in 1862, having been sent by Reis in June of that year to Mr. Horkheimer, who had left for England. The photograph was taken by Reis himself with his own camera, the exposure being managed by a slight movement of the foot, actuating a pneumatic contrivance of Reis’s own invention, which was originally designed to turn over the pages of a music book at the piano. Reis is here represented as holding in his hand the telephone with which he had a few days preceding (May 11, 1862) achieved such success at his lecture before the Freies Deutsches Hochstift (Free German Institute) in Frankfort (see p. 66). This instrument was constructed by Reis, young Horkheimer assisting him in the construction. Mr. Horkheimer has very obligingly indicated from memory the form of the instrument--but dimly seen in the photograph--in a sketch from which Fig. 13 has been prepared. Mr. Horkheimer adds that the cone was a wooden one; and that the square patch behind at the back was, he thinks, a box to contain an electro-magnet.

_Eighth Form._--LEVER FORM.

The Transmitter described with so much minuteness by Inspector von Legat in his Report on Reis’s Telephone in 1862 (see p. 70), differs from the earliest and latest forms, so much so that some have doubted whether this form was really invented by Reis. It is not described anywhere else than in Legat’s Report (in the “Zeitschrift” of the Austro-German Telegraph Union, reprinted also in Dingler’s Journal), except in Kuhn’s Handbook, where, however, the description is taken from Legat. Nevertheless a comparison of this instrument (Fig. 14) with the original model of the ear, from which Reis started, will show that it embodies no new point. There is, first, a conical tube to receive the sound, closed at its end with a tympanum of membrane. There is next a curved lever, _c d_, the lower end of which rests against the centre of the membrane. Thirdly, there is a vertical spring, _g_, which makes contact lightly against the upper end of the curved lever. Lastly, there is an adjusting screw. It may be further pointed out that in each case the current enters (or leaves, as the case may be) the lever at its middle point. This form of transmitter is so closely allied indeed to the primitive “ear” as to be alike in every feature save the external form of the sound-gathering funnel. The only reasonable doubt is not whether it be, as Legat asserts, Reis’s transmitter, but whether it ought not in chronological order to rank second. Legat’s paper was not published, however, till 1862, whilst the fourth form was described by Reis in 1861. No trace of any instrument corresponding in form to Fig. 14, save modern reproductions from Legat’s drawing, has been found. The instrument held by Reis in his hand in the photograph (Fig. 12) is so strikingly like the form described by Legat, that it furnishes an additional reason for accepting Legat’s statement that this transmitter really is Reis’s invention.

_Ninth Form._--TRANSITIONAL FORM.

Our knowledge of this form is derived solely from information and sketches supplied by Mr. E. Horkheimer, who assisted Reis in its construction. Figs. 15 and 16 are engraved after Mr. Horkheimer’s sketches. The conical mouthpiece was of wood: the contact pieces of platinum. The point _c_ was attached to a springy slip of brass, _g_, fixed across the wooden box; and the adjusting-screw, _h_, served to regulate the degree of initial pressure at the point of contact which controlled the current.

_Tenth Form._--THE SQUARE BOX.

The last form of Reis’s Transmitter is that which has become best known, being the only one (except Fig. 9) which found its way into the market. It is here named, for the sake of distinction, as the “Square Box” pattern. It consisted of a square wooden box, having a hinged lid. Fig. 17 is reproduced from Reis’s “Prospectus” (see page 85), whilst Fig. 18 is taken from Prof. Schenk’s biographical pamphlet.

In this instrument the idea of the human ear is still carried out. The tin funnel, with its flaring embouchure, still represents the auditory tube and pinna. The tympanum, no longer at the very end of the tube, is strained across a circular aperture in the lid. Upon it rests the strip of platinum foil which serves as an electrode, and resting in loose contact with this lies the little angular piece of metal which Reis called the “Hämmerchen.” Above all lay a circular glass disk (a cover to keep out the dust), which was removed when the instrument was used. So sensitive did this form prove itself that it was found unnecessary to speak right into the mouthpiece, and the speaker in practice talked or sang with his mouth at some little distance vertically above the instrument; a method which had the advantage of not so soon relaxing the membrane by the moisture of the breath. The figures show also the auxiliary apparatus attached at the side, consisting of a key for interrupting the circuit (added at first to enable the experimenters to single out the “galvanic tones” from the reproduced tones, and later applied, as Reis explains in his “Prospectus,” on page 87), and an electro-magnet to serve as a “call,” by which the listener at the other end could signal back to the transmitter.

This form of instrument, which has been so frequently described in the Text-books of Physics, was constructed for sale first by Albert of Frankfort, later by Ladd of London, König of Paris, and Hauck of Vienna. Further details concerning it will be found in this book, in Reis’s “Prospectus,” and in other contemporary documents.

Although this form is the one most commonly referred to as “the Reis Telephone,” it is evident from a consideration of the entire group of forms that Reis’s invention was in no way limited to one individual pattern of instrument. For in all these forms there was embodied one all-embracing principle;--that of controlling the electric current by the voice working upon a point of imperfect contact, by the agency of a tympanum, thereby opening or closing the circuit to a greater or less degree, and so regulating the flow of the current.

_B.--Reis’s Receivers._

_First Form._--THE VIOLIN RECEIVER.

The first form of apparatus used by Reis for receiving the currents from the transmitter, and for reproducing audibly that which had been spoken or sung, consisted of a steel knitting-needle, round which was wound a spiral coil of silk-covered copper-wire. This wire, as Reis explains in his lecture “On Telephony,” was magnetised in varying degrees by the successive currents, and when thus rapidly magnetised and demagnetised, emitted tones depending upon the frequency, strength, etc., of the currents which flowed round it. It was soon found that the sounds it emitted required to be strengthened by the addition of a sounding-box, or resonant-case. This was in the first instance attained by placing the needle upon the sounding-board of a violin. At the first trial it was stuck loosely into one of the _f_-shaped holes of the violin (see Fig. 19): subsequently the needle was fixed by its lower end to the bridge of the violin. These details were furnished by Herr Peter, of Friedrichsdorf, music-teacher in Garnier’s Institute, to whom the violin belonged, and who gave Reis, expressly for this purpose, a violin of less value than that used by himself in his profession. Reis, who was not himself a musician, and indeed had so little of a musical ear as hardly to know one piece of music from another, kept this violin for the purpose of a sounding-box. It has now passed into the possession of Garnier’s Institute. It was in this form that the instrument was shown by Reis in October 1861 to the Physical Society of Frankfort.

_Second Form._--THE CIGAR-BOX RECEIVER.

Later a shallow rectangular wooden box was substituted for the violin, and the spiral was laid horizontally upon it (Fig. 20). The date when this modification was made was either at the end of 1861 or the early spring of 1862. A cigar-box was the actual sounding-box, and the needle was supported within the coil, but not touching it, with its ends resting upon two wooden bridges.

_Third Form._--THE ELECTRO-MAGNET RECEIVER.

Though the precise history of this form of telephonic receiver is defective, there can be little doubt that it was conceived by Reis amongst his earliest researches. When there were in common use so many electric and telegraphic instruments in which an electro-magnet is employed to move an armature to and fro, it is not surprising that Reis should have thought of availing himself of this method for reproducing the vibrations of speech. Speaking of the two parts of his invention, the Transmitter and the Receiver, Reis himself says:[5] “The apparatus named the ‘Telephone,’ constructed by me, affords the possibility of evoking sound-vibrations in every manner that may be desired. _Electro-magnetism_ affords the possibility of calling into life at any given distance vibrations similar to the vibrations that have been produced, and in this way to give out again in one place the tones that have been produced in another place.” A remark, almost identical with this, is also made by Inspector von Legat (see p. 74) in his Report on Reis’s Telephone. It may be here remarked that the form of this receiver is known only from the figure and description given in that Report, and from the extract therefrom printed in Kuhn’s ‘Handbook’ (see p. 109). Reis seems to have very soon abandoned this form, and to have returned to the needle, surrounded by a coil, in preference to the electro-magnet. The electro-magnet form is, however, of great importance, because its principle is a complete and perfect anticipation of that of the later receivers of Yeates, of Gray, and of Bell, who each, like Reis, employed as receiver an electro-magnet the function of which was to draw an elastically mounted armature backwards and forwards, and so to throw it into vibrations corresponding to those imparted to the transmitting apparatus. Fig. 21 shows the disposition of the electro-magnet, and of its vibratory armature upon a sounding-board. This apparatus was a good deal larger than most of Reis’s instruments. The sounding-board was nearly a foot long: the coils of the electro-magnet were six inches long, and over an inch thick. The armature, a rod of iron of elliptical section, was affixed cross-wise at the end of a “light and broad” vertical lever, about seven inches long, which seems to have been made of wood, as in Legat’s Report it is also denominated as a “plank” (Balken).

_Fourth Form._--THE KNITTING-NEEDLE RECEIVER.

The final form adopted by Reis for his Reproducing-apparatus is that commonly known as the Knitting-needle Receiver. It differs only from the first form in that the needle and its surrounding spiral no longer stand upright on a violin, but lie horizontally upon a rectangular sounding-box of thin pine wood. The coil of silk-covered copper wire is wound upon a light wooden bobbin, instead of being twisted round the needle itself. Two wooden bridges stand upon the sounding-box, and through these pass the protruding ends of the needle, whilst an upper box or lid, hinged to the lower at the back, is added above. Figs. 22 and 23 show this form, the former being reproduced from Reis’s own Prospectus (see p. 85), the latter being from Müller-Pouillet’s ‘Text-book of Physics’ (see p. 95). Herr Albert, mechanician, of Frankfort, who made and sold the Reis telephones, says that the upper box was added at his suggestion. Originally it was so constructed (see Fig. 22), that when closed it pressed upon the steel needle. In the instruments of later date, the notches which fitted over the needle were cut so deeply (see Fig. 23), that the lid did not press upon the wire. Reis’s own instructions are (see p. 86) that the sound is intensified by firmly pressing the lid against the needle, as was done occasionally by the listeners who pressed their ears against the lid in order to hear more distinctly. The little key seen at the end of the sounding-box, in Fig. 22, was used for interrupting the current and so to telegraph back signals to the transmitter.

FOOTNOTES:

[3] Dr. Messel, F.C.S., a former pupil of Reis, and an eye-witness of his early experiments, makes, in a letter to Professor W. F. Barrett, the following very interesting statement: “The original telephone was of a most primitive nature. The transmitting instrument was a bung of a beer-barrel hollowed out, and a cone formed in this way was closed with the skin of a German sausage, which did service as a membrane. To this was fixed with a drop of sealing-wax a little strip of platinum corresponding to the hammer of the ear, and which closed or opened the electric circuit, precisely as in the instruments of a later date. The receiving instrument was a knitting needle surrounded with a coil of wire and placed on a violin to serve as a sounding board. It astonished every one quite as much as the more perfect instruments of Bell now do. The instrument I have described has now passed into the hands of the Telegraph Department of the German Government.” [The instrument now in the museum of the Reichs Post-Amt in Berlin is not this, but is the first of the “Improved” Telephones described later by Reis in his “Prospectus” (see p. 85), and is stamped “Philipp Reis,” “1863,” “No. 1.”] S.P.T.

[4] Or sometimes “tension-regulators,” though the latter term is acknowledged by most competent electricians to be indescriptive and open to objection.

[5] See _Die Geschichte und Entwickelung des Elektrischen Fernsprechwesens_ (issued officially from the Imperial German Post-office, 1880), p. 7.