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.
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
[Illustration: Fig. 4.]
[Illustration: Fig. 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.
[Illustration: Fig. 6.]
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.
[Illustration: Fig. 7.]
_Third Form._--THE COLLAR-BOX.
[Illustration: Fig. 8.]
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:--
[Illustration: Fig. 9.]
“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.
[Illustration: 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.
[Illustration: Fig. 11.]
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.
[Illustration: Fig. 12.]
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.
[Illustration: Fig. 13.]
_Eighth Form._--LEVER FORM.
[Illustration: Fig. 14.]
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.
[Illustration: Fig. 15.]
[Illustration: Fig. 16.]
_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.
[Illustration: Fig. 17.]
[Illustration: Fig. 18.]
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.
[Illustration: Fig. 19.]
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.
[Illustration: Fig. 20.]
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).
[Illustration: Fig. 21.]
_Fourth Form._--THE KNITTING-NEEDLE RECEIVER.
[Illustration: Fig. 22.]
[Illustration: Fig. 23.]
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.