Improvements in Apparatus for Making Records and Visible Indications of Sound-effects, and for Recording and Reproducing Sound Effects.
Year: 1896

page_text: Date of Application, 29th Feb., 1896
Complete Specification Left, 28th Nov., 1896-Accepted, 27th Feb., 1897
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Making Records and Visible
Indications of Sound-effects, and for Recording and
Reproducing Sound Effects.
I, MAX HOEFT, of 75 Krausenstrasse, Berlin, Germany, Manufacturer, do
hereby declare the nature of this invention to be as follows:-
This invention has reference to apparatus designed to enable sound waves-dug
for example to noises, musical sounds, and speaking-capable of being appreciated
by the eye, so that a measure of the nature quantität of the sound waves can be
obtained or recorded.
For this purpose, my apparatus comprises a membrane or diaphragm which is
caused to vibrate by the sound waves, and thereby to close or open, in a mechanical
manner, electrical circuits or to increase or weaken the intensity or strength of
electric currents.
The current impulses and current fluctuations thus produced are then proportional
to the quantity of the sounds acting upon the diaphragm, from which it follows
that the work done by the currents-whether the work be of a mechanical or
chemical nature is also proportional to the quantity of the sounds. In order to
render these electrical current impulses and current fluctuations visible to the eye,
I can proceed in various ways:-Thus I may pass the electrical current impulses
through measuring apparatus, such as for instance, galvanometers, compasses and
the like, and note the deflections of the pointer in these instruments, which is
preferably done automatically; or I may produce by means of these currents
chemical actions which can be measured in a voltameter; or I may with these
currents energise electromagnets, the fluctuations of the electrical conditions of
which serve to actuate suitable registering and recording apparatus.
Fig. 1 of the accompanying drawings is a diagrammatic representation of a very
simple arrangement of apparatus according to this invention. In this arrangement,
a diaphragm A, which may be of wood, metal, or other suitable material, is
suspended by a thin and very elastic metallic spring a, or is flexibly mounted in
any other suitable manner so as to be capable of vibrating. If, now, sound-waves
impinge upon this diaphragm-in front of which there may be provided a bell-
inouth or sound-funnel B, which, however, is quite superfluous in view of the great
sensitiveness of my apparatus, they will cause the diaphragm to vibrate. Its
vibrations will be transmitted to the contact-piece b, which is soldered to the lower
end of the metallic spring a, and this contact-piece will be thereby caused to move
alternately into and out of contact with a stud c. To the spring a there is
connected one pole of a galvanic element C, the other pole of which is electrically
connected with the stud c through the coils of a galvanometer D. At each make
and break of the circuit, the galvanometer needle is deflected, and from the number
of these deflections in a given time a deduction may be drawn as to the quantity
or pitch (hereinafter called pitch) of the sound-wares which have impinged upon
the diaphragm.
For the purpose of drawing this deduction there may be employed au apparatus
for counting the deflections of the needle. Such apparatus can be constructed in

page_text: Fig. 2 is a diagrammatic illustration of a method of constructing such an
apparatus. In accordance therewith the pointer of of the galvanometer D makes
contact, at each deflection, with a contact piece e. From this contact piece e lends
metallic conductor e to the winding of an electro magnet E, from which a
conductor e lends through a battery Fto the pointer d. In front of the legs of
the electro-magnet E there is arranged an armature which is pivoted at land
is provided with a writing pencil g. This writing pencil 7, when the armature is
caused to vibrate, comes in contnet with a strip of paper which is caused to travel
uniformly over a roller h, similarly to the arrangement in the well known Morse
apparatus.
The mode of operation of this device is as follows:-The vibrations of the
diaphragm A which is provided with a contact device G (shown in rear elevation
in Fig. 10) similar to tho well known carbon contact in a microphone, act to weaken
or to strengthen the current produced by the element C, the variations in the
electrical condition of the conductor leading to the galvanometer D, being rendered
visible by the deflections of the pointer d. When now the pointer d comes in
contact with the contact piece e, a current flows from the battery F through the
conductor e, the winding of the electro magnet E, the conductor e', and the
pointer d to the other pole of the battery F. This current energises the electro-
imagnet which then attracts the armature, which rebounds back again by its
elasticity when the energizing current circuit is opened at e by the return movement
of the pointer d. At each rebound of the armature, the writing pencil y produces
a mark on the paper strip i. The number of these marks is proportional to the
pitch of the sounds acting upon the diaphragm. As will be obvious, such a mark
could be produced on the attraction of the armature by the electro maguet. Also,
the roller can be coated with any suitable plastic material in which the pencil g
will produce impressions as in a phonograph.
Fig. 3 illustrates diagrammatically an arrangement similar to that Inst described,
but which in practice lins proved to be more efficient.
In this arrangement the diaphragm A which is assumed to be a small round plate
of fir wood, rests in an annular frame 1 of suitable material such as wood or hand
rubber, connected to the funnel B. A rubber cushion may serve as an intermediate
elastic support. The diaphragm is held in position by means of a metallic spring
which is bent over at its upper end and bears firmly against the diaphragm. For
the purpose of regulating the pressure of this spring, a suitable adjusting device
may be provided such for example as the set screw I shown by way of example in
Fig. 4. Upon the spring & lightly bears a platinum point or pin m carried by a
metallic spring n which is also arranged to be very finely adjusted by means of a
set screw, or in any other suitable manner. One pole of the galvanic cell C is
connected to the spring &. From the other pole leads a metallic conductor to the
winding of the electro-magnet D', and thence to the spring n. When the apparatus
is at rest, the platinum point or pin m bears lightly on the spring k. Consequently
a current passes constantly through the electro-magnet D, whose armature dis
therefore held attracted. When however sound waves reach the diaphragm A,
the latter is caused to vibrate, the vibrating motion being transmitted to the spring
and thence to the spring n. The result of this is that an exceedingly quick
opening and closing of the circuit, that is to say, diminution and increase of the
electric current, takes place at the point of contact between the contact pin m and
the spring k, and a corresponding vibration of the armature which moves about
the point 2 as a centre and is pressed by a detaching spring o against the contact
pin p when the attraction of the electro-magnet D decreases sufficiently. Each
time this takes place the circuit of a battery F is closed, and the armature of an
electro-magnet E attracted. When the current ceases to 'flow, this armature is
returned by its own elasticity into its position of rest, thereby making a mark upon
the paper stripi. Or if desired the movement of the armature may be utilized
to actuate another recording device, such for instance as a counting mechanism
acting after the manner of i revolution counter.

page_text: Fig. 4 illustrates in vertical section a contact device which is characterised by
an extreme sensitiveness and accuracy of transmission. In an annular frame H
there is mounted the diaphragm A which is kept in position in an elastic manner
by the pressure of the spring . At its upper end the spring carries an
extension which terminates in an insulating piece. On this insulating piece q
is fixed an elastic metallic spring n' which terminates in a contact pin m. One
pole of a galvanic cell is connected to the spring kl, and the other pole is connected
to the spring . The mode of operation is substantially the same as that of the
arrangement shown in Fig. 3.
In the contact device shown in vertical section in Fig. 5, one pole of the galvanic
cell is connected to a stapler on which is freely mounted a roller-shaped metal
blocks, provided with a metallic shank or stems which carries a metal knob all at
its lower end. To this knob s" there is electrically connected a contact pin m¹¹
which bears with a slight pressure on the elastic metallic spring t.
In consequence of the vibrations of the diaphragm A, the pin m" is alternately
repelled by the spring t and allowed to fall back again by gravity on to the said
spring, the circuit being thereby opened and closed in rapid succession.
Another contact device possessing very great sensitiveness, is illustrated in
vertical section in Fig. 6, and in rear elevation in Fig. 7. In this arrangement,
the diaphragm A is covered on its edge with a ring K of thin rubber which ends
to both sides of the diaphragm. On the front side, this rubber ring bears against
the casing I of the apparatus, whilst on the rear side a metal ring L screwed or
bolted to the casing serves to close in the same, and to prevent accidental alteration
of the position of the diaphragm.
The contact device proper is, in this case, formed by a thin metallic spring u
carrying a knob u' of any suitable material, which is firmly pressed against the
diaphragm so as to thereby produce a more powerful braking action on the diaphragm.
This braking action on the diaphragm is to be recommended, and is necessary in
order that the contact device shall act properly. The pressure exerted by the
knob u' may be regulated by means of a set screw which presses the bent lever v
(rotating in the bearing ') with more or less force against the spring .
On two
small metallic supports to which are insulated from the metal ring L, there is fixed
in electrical connection a small bright metal rod w' of circular form in cross section,
and on which there is pivoted a contact arm to. This contact arm carries, at
its upper end, a small contact screw to which is caused by gravity or by spring
pressure to bear against the spring with a slight and variable pressure.
pole of a galvanic cell is in electrical connection with one of the metal supports 1,
whilst the other pole is electrically connected with the spring u. The operation of
this arrangement is identical in all essential respects with that of the arrangements
hereinbefore described.
One
From the foregoing description, it will be obvious that a great many modifications
of my apparatus can be devised having a greater or less degree of sensitiveness.
The diaphragm A may be made of any suitable material, such as for examples,
wood, metal, hard rubber, horn, mica, paper, soft rubber and elastic fabrics. Its
shape may also vary greatly. It may be circular or polygonal. It may even be
replaced by a narrow strip, or even by a thread of suitable material. But in such
cases I recommend the arrangement of the strip or thread, to which a contact
piece must be attached, in front of a sounding board in order that the vibrations
of the strip or thread shall be rendered sufficiently powerful to make contact.
The size of the diaphragm does not play any decisive part; for instance, it is
quite sufficient to employ diaphragms of about the same size as those used in
ordinary telephonic apparatus, though diaphragms of considerably larger or smaller
size can be employed if desired.
It is possible, and in some cases advantageous, to dispense with a diaphragm, and
in its place to employ the casing in which the apparatus is enclosed. Obviously
the walls of such casing should be made of suitable material and of suitable
thickness, and the contact device should be attached to it in such a manner that

page_text: the vibrations of the wall of the casing shall produce exactly the same effect as
that produced by the use of a dinphragin.
As alrendy stated, the devices for rendering the effect of sound-waves visible,
and which are merely indicated in a diagrammatic manner in the nccompanying
drawings can be constructed in a great variety of ways. In addition to the devices
whereby a writing pencil g makes a record upon a moving strip of paper, a device
may be used whereby the movement of the armature is caused to actuate a
counting mechanism that is or may be similar to well known numbering apparatus,
and the construction nud operation of which is such that at each stroke of the
armature the number indicated will be one higher than the previous number. As
in such an arrangement the numbers will increase very rapidly, a modified arrange-
ment may be employed in which the vibrations of the armature are caused to
rotate a wheel having for instance 100 teeth, and which makes a completo
revolution before the counting apparatus advances to the next higher number.
Various other modifications of more or less like character may obviously be
employed if desired.
Apparatus constructed and operating as hereinbefore described can be employed
for a variety of purposes. Thus it may be employed for recording noises, as for
instance those produced by earthquakes, landslips or other disturbances of the
earth, whether such records be desired for scientific purposes or for practica!
purposes, for example, mining purposes. It may also be used in rooms, prison cells,
and other places for recording conversations or speech that may have taken place
therein. It can also be advantageously employed for scientific purposes, as for
example in the transmission of sound waves, or in the return-transmission of the
effects of sound waves. But probably the most important application of the
apparatus for practical purposes at present, is in telephony for recording the use of
a telephone, the apparatus providing a very correct means of estimating the dues
payable in respect of the use of the telephone, because the apparatus recurs only
the actually spoken words and sounds, and does not record the pauses in the
conversation.
This application of the apparatus to telephonic purposes can be effected in
various ways. Thus for example the apparatus may be hung up near to and
quite independently of the telephone; or the apparatus can be built direct in the
telephone.
Fig. 8 is a diagram illustrating an arrangement of this kind. Behind the month-
piece or funnel 13, of the telephone, there is arranged the circuit-closing diaphragm A
which makes and breaks contact between band c. Behind the circuit-closing
diaphragm A there is arranged the diaphragm proper A' of the telephone with the
microphone carbon contact G. When words are spoken into the telephone, the
sound waves cause the diaphragin A and also the diaphragm A'to vibrate, and ench
serves its particular purpose independently of the other.
In place of a single circuit-closing diaphragm A, two or more of such diaphragms,
or of their equivalents, may be employed, not only in this example, but in other
arrangements of my apparatus; these circuit closing diaphragms inay be arranged
in front of or behind the telephone diaphragm A, or it may be, partly in front and
partly behind the same.
It is also optional to employ in this case also, in place of the circuit-closing
diaphragms A, one of the equivalents therefor hereinbefore referred to. It is also
possible in this case, to employ, in place of a solid or imperforato circuit-closing
diaphragm A, a perforated diaphragm (see Figs. 9 and 11); or a vibrating cord or
string; or a vibrating strip or band.
Exhaustive practical experiments have shewn that by arranging one or more
circuit-closing diaphragins in front of or behind, or partly in front of, and partly
behind the microphone diaphragm, the transmission of sound in the telephone itself
is not only not hindered or interfered with, but the reproduced sound gains
considerably in purity of tone. This may be explained by the fact that the two

page_text: adjacent diaphragms enclose between them an air space which has au eminently
clastic action upon the vibrations of the diaphragms.
Fig. 12 illustrates diagrammatically an arrangement in which the microphone
diaphragm A" acts also as a circuit-closing diaphragm, the contact device 'b being
mounted directly thereon. In this case the microphone leads must be insulated
from the contact device bc. It is obviously also practicable, and even of
advantage from a practical point of view to employ, in place of the spring
suspension-mounting of the diaphragm A", another of the contact devices herein-
before described.
Now in order that only conversations actually carried on through the exchange
shall be recorded, it is advisable to carry the current lead of the recording
apparatus (as shown) through the well known' hook cut-out M, so that the apparatus.
will not operate so long as the receiver hangs on the book.
The recording apparatus proper which as before stated may be variously
modified, should in this case be actuated by the rotation of a toothed wheel N or
axle .r.
From the foregoing description it will be understood that by completing the
circuit through an electro-magnet E and a battery F, (Figs. 2 and 3) the effects
produced by the sound waves can be multiplied. If now this principle be so
applied that the writing pencil g acts like the stylus of a phonograph, then-if the
contact device be adjusted with a sufficient degree of fineness-corrugations or
wave-like impressions or indentations can be formed in a roller covered with plastic
material, and these impressions or indentations can be utilized in a reverse manner,
to reproduce the original sound waves, as with a phonograph. But the reproduced
sound can be increased in intensifying to any desired degree by reason of the
aforesaid multiplication. Now this is a matter of the greatest importance because
it is now for the first time possible to improve the phonograph in such a manner
that the same shall really satisfy practical requirements, since, by the entire
omission of the troublesome hearing tubes heretofore used, the sound reproduced
by the phonograph, can be easily intensified to such a degree that it can be clearly
heard by the car direct without further aid.
Improvements in Apparatus for Making Records and Visible
Indications of Sound effects, and for Recording and
Reproducing Sound Effects.
I, MAX HOEFT, of 75 Krausenstrasse, Berlin, Germany, Manufacturer, do
hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
This invention of improvements in apparatus for making records and visible
indications of sound effects and for recording and reproducing sound effects, is
designed more particularly for making a record whereby the time during which
telephonic apparatus has been in actual use for conveying telephonic messages, or
during which other sounds have been produced in the locality in which the
apparatus is located or the number of times the apparatus has been brought into

page_text: action in any known time, can be readily determined. In this sense the apparatus
may for brevity and distinction be called a conversation or sound counter.
shall now describe my invention by the aid of the drawing filed with my
Provisional Specification wherein Fig. 1 is a diagrammatic representation of a
very simple arrangement. of apparatus according to this invention. In this
arrangement, a diaphragm A, which may be of woul, metal, or other suitablo
material, is suspended by a thin and very elastic metallic spring a, or is flexibly
mounted in any other suitable manner so as to be capable of vibrating. If, now,
the sound waves proceeding from the telephone impinge upon this diaphragm-in
front of which there may be provided a bell-mouth or sound funnel B, which,
however, is quite superfluous in view of the great sensitiveness of my apparatus,
they will cause the diaphragm to vibrate. Its vibrations will be transmitted to the
contact-piece b, which is soldered to the lower end of the metallic spring a, and this
contact-piece will be thereby caused to move alternately into and out of contact
with a stud c. To the spring a there is connected one pole of a galvanic
clement C, the other pole of which is electrically connected with the stud a through
the coils of a galvanometer D. At each make and break of the circuit, the
galvanometer needle will be deflected, and from the number of these deflections in
given time a deduction may be drawn as to the pitch or quantity of the sounds
which have impinged upon the diaphragm.
For the purpose of easily drawing this deduction, there is employed according
to this invention an apparatus for counting the deflections of the needle. Such an
apparatus can be constructed in various ways.
Fig. 2 is a diagrammatic illustration showing how such an apparatus can be
constructed. In accordance therewith the pointer d of the galvanometer D makes
contact, at each deflection to the left, with a contact piece e From this contact
piece leads a metallic conductor to the winding of an electromagnet E, from
which a conductor e" leads through a battery F to the pointer d. In front of the
legs of the electro-magnet E there is arranged an armature which is pivoted at 1
and is provided with a writing pencil g. This writing pencil, when the armature
is caused to vibrante, comes in contact with a strip of paper i which is caused to
travel uniformly over a roller h, similarly to the arrangement in the well known
Morse apparatus.
The mode of operation of this device is as follows:-The vibrations of the
diaphragm A, which is provided with a contact device G (shown in rear elevation
in Fig. 10) similar to the well known carbon contact in a microphone, act to
wenken or to strengthen the current produced by the element C, the variations in
the electrical condition of the conductor lending to the galvanometer D, being
rendered visible by the deflections of the pointer d. When now the pointer d comes
in contact with the contact piece e, n current flows from the battery through the
conductor e, pointer d, contacte, conductor and the winding of the electro
magnet E, to the other pole of the battery F. This current energises the electro-
magnet which then attracts the armature which rebounds back again by its
elasticity when the energizing current circuit is opened at a by the return movement
of the pointer d. At each rebound of the armature, the writing pencil y produces
a mark on the paper strip i. The number of theso marks is proportional to the
pitch or quantity of the sounds acting upon the diaphragm, and approximately
represents the time the apparatus has been in use. As will be obvious, such
marks could be produced on the attraction of the armature by the electro magnet.
Also the roller can be coated with any suitable plastic material in which the
pencil will produce impressions as in a phonograph.
Fig. 3 illustrates diagrammatically an arrangement similar to that last described,
but which in practice has proved to be more efficient.
In this arrangement the diaphragm A which is assumed to be a small round plate
of fir wood, rests in an annular frame H of suitable material such as wood, or hard-
rubber, connected to the funnel B. A rubber cushion may serve as an inter-
mediate elastic support. The diaphragm is held in position by menus of a metallic

page_text: spring k which is bent over at its upper end and bears firmly against the diaphragm.
For the purpose of regulating the pressure of this spring, a suitable adjusting
device may be provided, such for example as the set screw shown by way of
example in Fig. 4. Upon the spring k lightly bears a platinum point or pin m
carried by a metallic spring n which is also arranged to be very finely adjusted by
means of a set screw, or in any other suitable manner. One pole of the galvanic
cell C is connected to the spring k. From the other pole leads a metallic conductor
to the winding of the electro magnet D' and thence to the spring n. When the
apparatus is at rest, the platinuin point or pin m bears lightly on the spring k.
Consequently a current passes constantly through the electro-magnet D, whose
armature d' is therefore held attracted. When however sound waves reach the
diaphragm A, the latter is caused to vibrate the vibrating motion being transmitted
to the spring & and thence to the spring n. The result of this is that an exceeding
quick opening and closing of the circuit, that is to say, diminution and increase of
the electric current, takes place at the point of contnet between the contact pin
and the spring k, and a corresponding vibration of the armature d which moves
about the point 2 as a centre and is pressed by a detaching spring o against the
contact pin p when the attraction of the electro-magnet D decreases sufficiently.
Each time this takes place the circuit of a battery Fia closed, and the armature/
of an electro-magnet E attracted. When the current ceases to flow, this armature
is returned by its own elasticity into its position of rest thereby making a mark
upon the paper strip i. Or if desired the movement of the armature may be
utilized to actuate another recording device, such for instance as a counting
mechanism acting after the manner of a revolution counter.
Fig. 4 illustrates in vertical section a contact device which is characterized by
an extreme sensitiveness aud accuracy of transmission. In an annular frame H
there is mounted the diaphragm A which is kept in position in au elastic manner
by the pressure of the spring . At its upper end the spring carries an
extension which terminates in an insulating piece g. On this insulating piece
is fixed an elastic metallic spring n which terminates in a contact pin m. Ouc
pole of a galvanic cell is connected to the spring &', and the other pole is connected
to the spring n. The mode of operation is substantially the same as that of the
arrangement shown in Fig. 3.
In the contact device shown in vertical section in Fig. 5, one pole of the
galvanic cell is connected to a stapler on which is freely mounted a roller-shaped
metal blocks provided with a metallic shank or stem s which carries a metal
knob a at its lower end. To this knob a" there is electrically connected a contact
pium which bears with a slight pressure on the elastic metallic spring .
ennsequence of the vibrations of the diaphragm A, the pin m" is alternately
repelled by the spring t and allowed to fall back again by gravity on to the said
spring, the circuit being thereby opened and closed in rapid succession.
Another contact device possessing very great sensitiveness, is illustrated in
vertical section in Fig. 6, and in rear elevation in Fig. 7. In this arrangement,
the diaphragm A is covered on its edge with a ring K of thin india rubber which
extends to both sides of the diaphragm. On the front side, this rubber ring bears
against the casing of the apparatus, whilst on the rear side a metal ring L
screwed or bolted to the casing, serves to close in the same, and to prevent
accidental alteration of the position of the diaphragm.
The contact device proper is, in this case, formed by a thin metallic spring
carrying a knob w' of any suitable material, which is firmly pressed against the
diaphragm so as to thereby produce a more powerful braking action on the
diaphragm. This braking action on the diaphragm is to be recommended, and is
necessary in order that the contact device shall act properly. The pressure exerted
by the knob u may be regulated by means of a set screw which presses the bent
lever (rotating in the bearing ) with more or less force against the spring a
On two small metallic supports w which are insulated from the metal ring L, there
is fixed, so as to be in electrical connection with the supports w, a small bright
metal rod of circular form in cross section and on which there is pivoted a

page_text: contact arm to. This contact arm carries, at its upper end, a small contact
screw which is caused by gravity or by spring pressure to bear against the
spring with a slight pressure. One pole of a galvanic cell is in electrical
connection with one of the metal supports e, whilst the other pole is electrically
connected with the spring . The operation of this arrangement is identical in all
essential respects with that of the arrangements hereinbefore described.
From the foregoing description, it will be obvious that a great many
modifications of my apparatus can be devised having a greater or less degree of
sensitiveness.
The diaphragm A may be made of any suitable material, such as for examples,
wood, metal, hard india rubber, horn, mica, paper, soft india rubber and elastic
fabrics. Its shape may also vary greatly. It may be circular or polygonal. It
may even be replaced by a narrow strip, or even by a thread of suitable material.
But in such cases I recommend the arrangement of the strip or thread to which a
contact piece must be attached, in front of a sounding board in order that the
vibrations of the strip or thread shall be rendered sufliciently powerful to make
contact. The size of the diaphragm does not play any decisive part; for instance,
it is quite sufficient to employ diaphragms of about the same size as those used in
ordinary telephonic apparatus, though diaphragms of considerably larger or smaller
size can be employed if desired.
It is possible, and in some cases advantageons, to dispense with a diaphragm,
and in its place to employ the casing in which the apparatus is enclosed.
Obviously the walls of such casing should be made of suitable material and of
suitable thickness, and the contact device should be attached to it in such a manner
that the vibrations of the wall of the casing shall produce exactly the same effect as
that produced by the use of a diaphragm.
As already stated, the devices for rendering the effect of sound-waves visible,
and which are merely indicated in a dingrammnatic manner in the drawings referred
to, can be constructed in a great variety of ways. In addition to the devico
whereby a writing pencil g makes a record upon a moving strip of paper, a devico
may be used, as hereinbefore mentioned, whereby the movement of the armature f
is caused to netunte a counting mechanism that is or may be similar to wellknown
numbering apparatus, and the construction and operation of which is such that at
cach stroke of the armature the number indicated will be one higher than the
previous number. As in such an arrangement the numbers will increase very
rapidly a modified arrangement may be employed in which the vibrations of the
armature are caused to rotate a wheel having for instance 100 teeth, and which
makes a complete revolution before the counting apparatus advances to the next
higher number. Various other modifications of more or less like character may
obviously be employed if desired.
Apparatus constructed and operating as hereinbefore described can be employed
for a variety of purposes. Thus it may be employed for recording noises, as for
instance those produced by earthquakes, laudslips or other disturbances of the
earth, whether such records he desired for scientific purposes or for practical
purposes, for example mining purposes. It may also be used in rooms, prison cells
and other places for recording conversations or speech that may have taken place.
therein.
The most important application of the apparatus for practical purposes at present,
is in telephony for recording the use of a telephone, the apparatus providing a very
correct means of estimating the dues payable in respect of the use of the telephone,
because the apparatus records only the actually spoken words and does not record
the pauses in the converention.
This application of the apparatus to telephonic purposes can be effected in
various ways. Thus for example the apparatus may be hung up near to and
quite independently of the telephone; or the apparatus can be built direct in the
telephone.
Fig. 8 is a diagram illustrating an arrangement of this kind. Behind the mouth-

page_text: piece or funnel B of the telephone, there is arranged the circuit closing diaphragm A
which makes and breaks contact between b and c. Behind the circuit-closing
diaphragm A there is arranged the diaphragm proper A' of the telephone with the
microphone carbon contact G¹. When words are spoken into the telephone, the
sound waves cause the diaphragm A and also the diaphragm A' to ribrate, and each
serves its particular purpose independently of the other.
In place of a single circuit-closing diaphragm A, two or more of such diaphragms,
or of their equivalents, may be employed, not only in this example, but in other
arrangements of my apparatus; these circuit-closing diaphragms inay be arranged
in front of or behind the telephone diaphragm A', or it may be, partly in front and
partly behind the same.
It is also optional to employ in this case also, in place of the circuit-closing
diaphragms A, one of the equivalents therefor herein before referred to. It is also
possible in this case, to employ, in place of a solid or imperforate circuit-closing
diaphragm A, a perforated diaphragm (see Figs. 9 and 11); or a vibrating cord or
string; or a vibrating strip or band.
Exhaustive practical experiments have shown that by arranging one or more
circuit-closing diaphragms in front of or behind, or partly in front of, and partly
behind the microphone diaphragm, the transmission of sound in the telephoue itself
is not only not hindered or interfered with, but the reproduced sound gains
considerably in purity of tone. This may be explained by the fact that the two
adjacent diaphragms enclose between them an air space which has an eminently
elastic action upon the vibrations of the diaphragms. Fig. 12 illustrates diagram-
matically an arrangement in which the microphone diaphragm A" acts also as a
circuit-closing diaphragm, the contact device being mounted directly thereon.
In this case the microphone leads must of course be insulated from the contact-
device b c. It is obviously also practicable, and even of advantage from a practical
point of view, to employ, in place of the spring suspension-mounting of the
diaphragm A, another of the contact devices herein before described.
Now in order that only conversations actually carried on through the exchange
shall be recorded, it is advisable to carry the current lead of the recording apparatus
(as shown) though the well known hook cut-out M, so that the apparatus will not
operate so long as the receiver hangs on the hook.
The recording apparatus proper which, as before stated may be variously
modified, should in this ense be actuated by the rotation of a toothed wheel N or
axle.z.
From the foregoing description it will be understood that by completing the
circuit through an electro-magnet E and a battery F (Figs. 2 and 3) the effects
produced by the sound waves can be multiplied. If now this principle be so applied
that the writing pencil g acts like the stylus of a phonograph, then,-if the contact
device be adjusted with a sufficient degree of fineness-corrugations or wave-like
impressions or indentations can be formed in a roller covered with wax or other
suitable plastic material, such as used in phonographs, and these impressions or
indentations can be utilized in a reverse manner, to reproduce the original sound
waves, as with a phonograph. But the reproduced sound can be increased in
intensity to any desired degree by reason of the aforesaid multiplication. Now
this is a matter of the greatest importance, because it is now for the first time
possible to improve the phonograph in such a manner that the same shall really
satisfy practical requirements, since the troublesome hearing tubes heretofore used
can be omitted, because the sound reproduced by the phonograph will be of such
a loudness that it can be clearly heard by the ear direct without further aid.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. For making records and visible indications of sound effects, apparatus wherein
the sound effects are caused to alternately close and open electrical circuits or to

page_text: strengthen and weaken electric currents, and the intermittent or varying currents
thus obtained are caused to produce magnetic effects by which another electrical
circuit is alternately closed and opened, or another current alternately strengthened
and weakened, the intermittent or varying currents thus obtained being utilized to
operate a recording device or both a recording device and a visual indicating device
as set forth.
2. For making records and visible indications of sound effects, apparatus in which
the sound is caused to act upon one or more diaphragms A or its or their equivalent
as berein set forth, and by means of the vibrations thereof this produced are caused
to operate by mechanical means, a contact-making and breaking device whereby an
electric circuit is alternately closed and opened, or an electric current is alternately
strengthened and weakened, the resulting electric currents or current acting either
to drive a recording device directly, or to produce magnetic effects by which
further electric currents or circuits are produced or influenced so as to operate the
recording device as set forth.
3. The combination of apparatus of the kind referred to in the preceding claims,
with a telephone the said apparatus being arranged either near to but independent
of the telephone so as to record the sounds and words spoken into it; or being
combined with the telephone in such a manner that the diaphragm A is either
represented or constituted by the wall or casing of the telephone, or is in the form
of one or more plates, diaphragms, rods, or threads, arranged in front of or behind
or partly in front of and partly behind, the microphone diaphragm of the telephone,
substantially as described.
4. The combination of apparatus of the kind referred to in Claims 2, and 3 with
a phonograph in such a manner that sound waves are multiplied and recorded by
the aid of electric currents on the roller of the phonograph as set forth.
5. In apparatus of the kind referred to in the preceding claims for counting
telephonic conversations, a contact device adapted to be oscillated by the vibrations
of the elastic medium A, and comprising an adjustable metal spring & arranged to
bear against the said elastic medium A, and connected with one pole of an electric
generator C, and a contact arm that is connected with the other pole of the
electric generator and carries a contact pin m or m³ this contact arm being either
in the form of an arm that is pressed against the spring & by spring pressure, or
of an arm n', or tell that is pressed against the said spring by the action of gravity
substantially as herein described.
6. Apparatus for counting telephonic conversations constructed, arranged and
operating as herein before described with reference to and shown in Fig. 2;
in Fig. 3; and in Fig. 12, or modified according to Fig. 8.
Dated this 28th day of November 1896
Dated this 28th day of November 1896.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.