An Improved Method of and Apparatus for Reproducing Sonorous Vibrations with Increased Amplitude, and its Application to Industrial and Useful Purposes.
Year: 1890

page_text: Date of Application, 26th Sept., 1890
Complete Specification Left, 26th June, 189'-Accepted, 19th Sept., 1891
PROVISIONAL SPECIFICATION.
An Improved Method of and Apparatus for Reproducing Sonorous
Vibrations with Increased Amplitude, and its Application to
Industrial and Useful Purposes.
I, ROBERT HOPE-JONES, of 11 Huskisson Street, Birkenhead, in the County
of Chester, Electrical Engineer, do hereby declare the nature of this invention to
be as follows:-
Attempts have been made to increase the volume or power of the human voice
and other considerable sources of sound, but none of the devices hitherto employed
have proved successful in practice.
Now I have discovered various means by which these sounds may be magnified
to a considerable extent, and instruments made in the manner herein delineated are
capable of yielding surprising and thoroughly practical results.
This invention is applicable as a receiver, as a relay, and as an auxiliary to a
transmitter in telephonic apparatus:
As a sensitive receiver for telegraphic or other electric signals or impulses:
As an adjunct to a phonograph, graphophone or similar instrument, by means of
which both the impressions and reproductions can be strengthened:
As an apparatus to assist in forming permanent records of sonorous or other
vibrations :
As a speaking apparatus by which one or more individuals can speak or sing to
enormous audiences :
As a means of enabling the one in command to make his orders heard either on
board ship, on the battle field, at fires, or in any place where the ordinary voice
would not be distinguished:
As an apparatus by which, in foggy weather, or at night, or otherwise, one ship
can speak to another, or a person, or phonograph or other instrument, can shout
the name of a lighthouse or other information or sound to be heard at very great
dista ices:
As a means of communication from or between moving carriages or trains :
For the purpose of increasing, variably or otherwise, the volume of sound emitted
by bells, an organ, or other musical instrument or instruments, thereby avoiding the
necessity of securing great power in designing such instruments:
As a means of increasing the efficiency of speaking tubes.
The original vibrations from the voice, telephone, phonograph, or other source
may be made to control the emission or flow of steam, gas, or other fluid, by means
of a diaphragm, valve, or combination of the two, the said valve or its equivalent
being so arranged that the movement produced by the original sound shall (in
contradistinction to other devices which may have been previously tried) open or
close a number of openings simultaneously, or one opening which is diverted, zig-
zagged or coiled, so as to be of a considerable length, and thus cause the steam or
fluid to form vibrations of much greater amplitude but of the same form and
frequency as the original ones.
Or, the original vibrations may be made to increase or diminish the intimacy of
contact between a number of loose particles, or to open and close the pores of some
pervious material, so as to regulate or govern the flow of steam or other fluid
through or between these materials, and so to act in the same mauner as the afore-
said valve.
Or, the original vibrations may be applied in such a manner as to vary the
co-efficient of friction between two or more surfaces, and so to govern the application
of an extraneous mechanical force to the diaphragm, sound-board, valve or other
device to be actuated.

page_text: Or, the original vibrations, being transformed into corresponding electrical
vibrations by means of a microphone or other form of telephonic transmitter, may
be made to circulate through the coils of an electro magnet or magnets, and to act
upon, and be re-acted upon by, a conductor of electricity which is caused to move
or revolve by some extraneous force in such a manner that a portion of this
extraneous force will be applied to produce secondary vibrations in exact accord
with the varying electrical and magnetic powers at work between the disc and the
magnet.
When sounds are magnified by the employment of a valve distinct from the
diaphragm, it is necessary so to arrange matters that a very large area of opening
will result from an almost inappreciable movement of the valve, it is also found
advisable, whenever practicable, to employ a valve which shall not be impeded in
its action by the steam pressure or by friction between the surfaces due to the same.
For this purpose, the valve is sometimes composed of two accurately fitting tubes
one sliding within the other, the tubes being pierced transversely by a considerable
number of fine saw-cuts in such a manner that, when placed in the position of
coincidence, the steam or fluid can pass from a casing surrounding the outer tube
through the saw-cuts and out of one or both ends of the inner tube (or vice versa)
and from thence to the apparatus it is desired to actuate or into the atmosphere
through a trumpet-shaped opening.
Such a valve may be actuated either by pulsations of the air directly or
by a diaphragm or similar body which is itself set in motion by sonorous
pulsations.
It is sometimes advisable, in order to avoid sideway thrust and consequent binding
of the valve, to convey the vibrations of the diaphragm or diaphragms to the valve
by means of one or more wires or rods; or, by closing one end of the inner portion
of the valve and connecting this inner portion with pressure from the boiler (and
leaving the casing open to the atmosphere) and so causing the valve to be pushed
out by the pressure of steam against a diaphragm, sound-board, or other vibrating
body.
It is occasionally advisable to employ light levers between the diaphragm and
the valve in order to increase either the amplitude or power of the movement of the
latter.
Another form of balanced valve may be thus described:
-
A number of thin concentric tubes are so arranged as to form a series of concentric
annular spaces between them for the passage of steam, or other fluid. At one end,
a chamber is arranged with openings into each alternate annular space, and this
chamber is supplied with steam from a boiler, or with other fluid under pressure,
the remaining alternate annular spaces are open at the same end of the tube to the
atmosphere through a trumpet mouth. The other end of this series of tubes is
closed or almost closed by a light disc valve which may be sometimes coated with a
soft material, and this disc valve, together with the free ends of the tubes, may, if
desired, be enclosed in a casing which is supplied with sufficient pressure to exactly
balance and neutralise that exerted upon the disc valve by the steam within the
annular spaces.
The disc valve may be vibrated by means of a wire, or rod, passing through a
stuffing box or its equivalent in the latter named casing, or through one of the
tubes, or through both of these; or the disc may be mounted on one end of a
light lever, the other end of which is actuated by a diaphragm, the said lever being
made to pass through the last named casing at the point of its fulcrum.
In instruments where the dia. itself is used to control the flow of the fluid, a
great many varieties of arrangement have been found to yield satisfactory results.
In one form, the diaphragm, which is sometimes covered with india-rubber,
leather, cloth or other material, is brought so near the open ends of two or more
thin concentric tubes (such as previously described) as almost or entirely to prevent
the flow of the gas or fluid, but yet leaving the diaphragm more or less free to
vibrate.

page_text: In another form, similar concentric tube arrangements are placed on each side of
the diaphragm, which, in this case, will be actuated by a lever or by a rod or wire
passing through one of the tubes.
Or, a wheel with flat periphery, which may be coated with wash-leather, paper,
resin, oil, dust, or other material, is caused to revolve by some mechanical
extraneous force. Upon the periphery of this wheel, a flat spring rests, which
spring is connected rigidly or by means of a section of rubber or other material to
a large receiving diaphragm or sound-board near its centre. A smaller diaphragm,
against which the original sound vibrations are caused to impinge, is placed with its
axis at right angles to the spring and with its centre opposite the point of contact
between the spring and the wheel. A short rod, which may be furnished with a
section of india-rubber, is so placed between the diaphragm and the spring that one
end presses lightly against the diaphragm and the other end against the spring,
thereby slightly increasing the friction between the wheel and the spring, and
consequently increasing the pull exerted by the spring upon the large or receiving
diaphragm. In the position of rest, the co-efficient of friction between the wheel
and the spring and the consequent pull upon the receiving diaphragm remain
constant, but when sound vibrations impinge against the smaller diaphragm, the
varying impulses transmitted therefrom by the little rod increase or diminish the
friction and so vary the pull on the spring as to throw the larger diaphragm or
sound-board into vibrations which correspond in form with the original ones, but are
much greater in amplitude.
It is generally advisable to increase the number of points of friction between the
body moved by the extraneous force and the body connected to the diaphragm.
This may be done in a variety of ways, two of which shall be named :-
-
(1) A bundle of strips of thin paper, mica, thin metal or, other material is
connected to the centre of a large receiving diaphragm by one end, the other or
free end of the strips being embraced on their flat sides by a pair of smaller
diaphragms, these smaller diaphragms bear upon the strips by little posts or pegs,
which, when the diaphragms are thrown into vibration by being connected to a
commion mouth-piece, will compress or relax the bundle of strips. A revolving
shaft is now placed with its axis parallel to the face of the large sound-board and
at right angles to the narrow faces of the thin strips, and on this axle are fixed a
number of circular discs of paper or other thin material in such a manner that one
disc will come between each and every pair of the strips. The rotation of these
discs, which have the free ends of the strips interleaved between them, will tend to
drag the strips in such a direction as to produce a slight pull upon the large
diaphragm or sound-board. When the small diaphragms are set into vibration, this
pull will be enormously increased and reduced, for the co-efficient of friction
between each pair of surfaces will be simultaneously varied.
(2) A number of wires may be stretched between a large receiving sound-board
and one or more transmitting diaphragms, a grooved revolving pulley may be so
placed as to bear against these wires, so that they shall bend partly round its
surface. The tightening and loosening of these wires, due to the original vibrations
which are caused to fall upon the smaller diaphragms, will increase and diminish the
friction between the pulley and each wire, and so throw the sound-board into..
vibrations of large amplitude.
It is usual for the active part of the periphery of the pulley to turn away from
the sound-board.
When an undulating current of electricity or a number of these, from one or
more of some sort of telephonic transmitter or similar instrument, are used in con-
nection with sound magnifying apparatus, the current may be caused to circulate
round the coils of one or more magnets so arranged as to actuate any form of the
diaphragm, valve, or frictional arrangements, above described.
Or, the lines of magnetic force may be caused to act directly or through the
agency of a magnet or magnets upon a moving or revolving mass of metal or other

page_text: :-
conductor of electricity. Many instruments can be devised which magnify sound
in this last named manner, two of which shall be described by way of illustration:
(1) An accurately balanced sphere or disc of metal is mounted upon a small shaft
which runs perfectly truly in a pair of bearings. These bearings are fixed, rigidly
or by means of stout blocks of india-rubber, to a large sounding-board. The shaft
is furnished with a small fixed pulley, which is driven (at right angles to the sound-
board) by means of a light smooth and jointless belt from a large hand-wheel,
engine, or other motive power. Now, provided the speed he constant, the engine
belt will exert a uniform pull on the sound-board through the shaft and its bearings ;
but if active electro magnets, which are mounted on a separate base, are brought
so close that the lines of force from their poles shall be cut by the revolving sphere
or disc, the said disc or sphere will be retarded and the belt will, in consequence,
have to exercise a much greater pull. If now the undulating current from the
transmitting apparatus before named be made to circulate through the coils of the
magnet, the varying electrical vibrations will be transformed into mechanical
impulses which are strong enough to throw the large sound-board into considerable
vibration.
(2) In another form, the bearing of the disc may be fixed rigidly and the disc
rotated as before. A number of electro magnets, each one of which is mounted on,
or connected with, a sound-board, is placed so as to embrace, or come close to, the
disc at various points. Undulating currents, originated by sound waves now being
passed through the coils of these magnets, increase the mechanical energy absorbed
in revolving the disc and give rise to a reflex action on the magnets themselves,
which magnets will be found to throw the sound-board into powerful secondary
vibrations.
It is often advisable, in these cases, to use permanent magnets surrounded with
coils of wire or furnished with soft iron pole pieces, which are so surrounded.
For use in connection with organs or other musical instruments, it is often
advisable that apparatus for receiving the primary vibrations should be provided in
multiple and placed near certain departments of the instrument, and an arrange-
ment provided for enabling the performer to bring one or more of these parts of
the magnifying apparatus into action at will. It is not necessary that the whole of
the instrument, or indeed any part of it, should be placed absolutely in the building
in which it is to be heard, for, by means of a sounding-tube, a solid rod, or an
electric wire, or a number of these, the sound may be conveyed to the magnifiers
which will themselves be placed within the building.
In an organ, the swell box need not he provided with shutters for the trans-
mitting apparatus may be placed in a small box with variable opening within the
swell organ and a most wonderful crescendo or diminuendo can be thus obtained.
In many of the above forms of instrument, which are actuated by means of a
diaphragm, it is sometimes advisable that the diaphragm should give off its
vibrations through a light spring or section of india-rubber.
It will, of course, be obvious that any two or more of the devices above described
may be combined for the purposes of magnifying sound.
When using any of the above arrangements of instrument in connection with the
phonograph or graphophone, these latter may be made to take the place of the
original voice or other source of sound; or the sounds which are to be recorded
may themselves first be strengthened by means of the devices herein described.
It is found advisable, in some cases, to provide a mouth-piece in connection with
the diaphragm, which mouth-piece will vary in size and shape according to the
nature of the sounds to be dealt with.
In using the word "diaphragm," I have intended to refer to any solid body
capable of being vibrated by sound.
Dated this 25th day of September 1890.

page_text: COMPLETE SPECIFICATION.
An Improved Method of and Apparatus for Reproducing Sonorous
Vibrations with Increased Amplitude, and its Application to
Industrial and Useful Purposes.
I, ROBERT HOPE-JONES, of 11 Huskisson Street, Birkenhead, in the County of
Chester, Electrical Engineer, 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 relates to apparatus for reproducing sound vibrations on a
magnified scale, a practical apparatus of this description, which will magnify the
vibrations to many times their original amount, being a great desideratum and
capable of employment for a great variety of purposes, some of which are
enumerated hereinafter.
Attempts have hitherto been made to increase the volume or power of the human
voice and other considerable sources of sound, but none of the devices hitherto
employed have proved very successful in practice. I have, however, discovered
various means by which such sounds may be magnified to a considerable extent, and
in a thoroughly practical manner.
In carrying the invention into effect, I so control, regulate or vary the flow or
emission of a fluid under pressure, or the amount of mechanical friction applied to a
moving body, or the amount of electrical or magneto-electrical retardation offered
to a moving electric conductor, that successive portions of the energy or motive
power of said fluid, or moving body or conductor, varying in accordance with the
vibrations to be magnified, are utilised to produce, directly or indirectly, corre-
sponding vibrations of greater amplitude.
Figures 1 to 25 show various forms of apparatus in which a fluid under pressure
is employed as a means for producing the magnified vibrations.
Figures 26 to 36 illustrate various forms of apparatus in which the sound vibra-
tions are reproduced in a magnified manner in accordance with a varying amount of
mechanical friction applied to a moving body.
Figures 37 to 51 show various forms of apparatus in which the sound vibrations
are reproduced on a magnified scale in accordance with a varying amount of
electrical or magneto-electrical retardation applied to a moving electrical con-
ductor.
The principle upon which I construct the various apparatus shown in and
described with reference to Figures 1 to 25 consists in causing the original sound
vibrations to so control the flow or emission of a fluid under pressure that a series.
of fluid impulses or vibrations shall be produced having the same rate of sequence
and more or less the same form as the original vibrations, but having a greater
amplitude, the magnified impulses or vibrations being conveyed either directly to
the air or directly or indirectly to a vibratory diaphragm or similar body capable
of vibration under their influence, and the resulting sounds being of the same pitch,
and more or less of the same quality, as the original sounds, but having a much
greater intensity.
In applying the foregoing principle to the production of a practically working
apparatus embodying the invention, it is necessary so to construct such apparatus
that a very minute primary vibration or impulse shall produce a relatively large
secondary impulse or vibration.
This may be effected in part by employing the fluid, the flow or emission of which
is to be controlled, at very high pressures. There are, however, many practical
objections to the use of very high pressures, although their employment is not
absolutely impossible.
In order, therefore, to construct an apparatus which will work in a thoroughly
practical manner with the operating fluid at pressures ordinarily obtainable, it is

page_text: necessary that the controlling or regulating device of the apparatus shall be so
arranged and constructed that a very minute movement of its movable member
shall bring a comparatively large controlling or regulating action to bear upon
the operating fluid. In other words, it is necessary that a very minute movement
of the said movable member (hereinafter called the "controlling valve") shall
effect the release or arrest of a comparatively large body of the fluid under
pressure, that is, it shall permit a comparatively large amount of the fluid to pass,
or prevent it from passing, through or past the stationary (or relatively
stationary) member of the controlling device (hereinafter called "the controlling
valve seat").
To this end, I construct the valve, or valve seat, or both, with a series of
very small or narrow openings, or with one or more narrow openings of con-
siderable length so arranged that a very minute movement of the valve will
open or close them all simultaneously and will thus open or close a comparatively
large area for or against the passage of the operating fluid and I have found,
as the result of a long series of experiments, that, no matter what the particular
form of the valve and its seat, it is essential for the production of a practicably
working apparatus-which will magnify the primary sounds considerably beyond
their original intensity and with pressures ordinarily obtainable-that the valve
and its seat be arranged as aforesaid. The opening or openings is or are
preferably so arranged that, while occupying a comparatively small area, they
present a much extended edge over or past which the operating fluid may
escape. The controlling valve is also balanced or so arranged that it will work
freely under the very slight impulses imparted to it.
The primary diaphragm, which, in most cases, receives the original vibrations,
may be attached to or it may bear against, or be otherwise connected directly with,
the controlling valve, or it may be connected indirectly to said valve by any
suitable arrangement of levers. Or the vibrations of the primary diaphragm may
be transformed into a series of electrical impulses as in a telephonic transmitter
and such impulses may be imparted to the valve in any suitable manner. Or the
primary vibration may be transformed, by means of a phonograph, into a series of
indentations or punctures upon or in a recording surface in the well known manner,
and these again may be employed to operate the controlling valve either directly
or through levers or through the intermediary of the transmitting diaphragm usually
employed in phonographs.
The magnified vibrations or impulses may be conveyed directly to the air by
means of a suitably shaped trumpet mouth, or they may be transmitted in an indirect
manner through the medium of a larger secondary diaphragm acted upon either
directly or indirectly by the operating fluid. It is even possible to cause such
secondary diaphragm to act as a primary diaphragm to a second controlling device
of larger dimensions than the first.
The drawings (Figures 1 to 25) show various forms of apparatus constructed
upon the lines briefly sketched above;
Figures 1 to 22 relating to apparatus adapted to be worked by gaseous fluids,
generally air or steam, and
Figures 24, 24 and 25 illustrating a form of apparatus more especially adapted
to be operated by liquid fluids, such as water.
In these :-
Figure 1 is a central section of a type of apparatus in which the primary
diaphragm itself forms the valve of the controlling device.
Figure 2 is a plan of same with the mouthpiece, diaphragm, etcetera, removed.
Figure 3 is a section on line z z, Figure 2.
Figure 4 is an end elevation of a part of an adjusting device shown in Figure 3,
and employed for a purpose hereinafter described.
Figure 5 is an enlarged view of a portion of the valve seat shown in Figure 2.
Figure 6 is a sectional elevation of a duplicate form of apparatus of the type
shown in Figure 1, the external lagging being removed.

page_text: Figure 7 is a longitudinal section of a type of apparatus in which the valve is in
the form of a flat disc and is connected indirectly with the primary diaphragm by
means of a lever.
Figure 8 is a transverse section on line Y Y, Figure 7, as seen from below.
Figure 9 is a transverse section cn line Y¹ Y¹, Figure 7, as seen from above.
Figure 10 is a central longitudinal section illustrating another type of apparatus
in which there is employed a cylindrical valve bearing against and worked directly
by the primary diaphragm.
Figure 11 is an end view of the valve seen in Figure 10.
Figure 12 is a transverse section on linea, Figure 10.
Figure 13 is a longitudinal section showing a modification of the preceding
arrangement, in which the cylindrical valve is more or less rigidly attached to the
primary diaphragm.
Figure 14 is a sectional elevation showing another modification in which the
cylindrical valve is attached to an extended wire secured at one end to the
diaphragm.
Figure 15 is a longitudinal section, on a larger scale, of the controlling device of
the apparatus shown in Figure 14.
Figure 16 is an enlarged sectional view of an adjusting device employed in the
apparatus shown in Figure 14.
Figures 17 and 18 are longitudinal section and elevation respectively, on a much
enlarged scale, of a portion of the aforesaid cylindrical valve and of a slightly
modified form of seat therefor.
Figure 19 is a modified form of the apparatus in which two valves and diaphragms
are employed.
Figure 20 is a longitudinal section of a form of apparatus in which the sound
vibrations act directly on the controlling valve itself.
Figure 21 is a plan of a modified form of valve scat hereinafter described.
Figure 22 is a longitudinal section through the discharge pipe or trumpet mouth
of any of the preceding apparatus, and illustrates an arrangement by which the
magnified fluid vibrations or impulses are caused to act upon an enlarged secondary
diaphragm.
Figure 23 is a longitudinal section of a modified form of apparatus in which the
magnified vibrations act on a large secondary diaphragm.
Figures 23 and 23 are enlarged section and plan respectively of one of the
valve seats shown in Figure 23.
Figure 24 is a longitudinal section, showing another type of apparatus which is
adapted more especially to be operated by the pressure of a liquid such as water,
the valve being, in this case, a flat disc connected to the primary diaphragm in such
manner as to be capable of vibrating slightly in a direction perpendicular to its
face, and the magnified vibrations or impulses being conveyed to a large secondary
diaphragm, as in the case of the apparatus shown in Figures 22 and 23.
Figure 24 shows a modified arrangement of the apparatus depicted in Figure 24.
Figure 25 is a section (on a much enlarged scale) of the valve and valve seat
shown in Figure 24.
Referring first to Figures 1 to 5 :-
A, is the primary diaphragm which is adapted to receive the sound vibrations
through a suitable mouthpiece B. The diaphragm is secured at its edges to the
base C of the mouthpiece, by means of an annular ring C and screws c.
63
The base C is adjustable within the casing C, being, to that end, screwed therein
as shown at c. To attain a very fine adjustment, the base is provided, on its
periphery, with a circular rack c² into which a pinion gears, the said pinion being
rotated at will from the exterior of the apparatus by means of a key or milled head
attached to the end of its shaft c. The pinion and its shaft may be upheld in
position by means of a small pin passing through a fixed sleeve and resting
within a peripheral groove e in the shaft. When the base C of the mouthpiece
is to be removed or when a very coarse adjustment is required, the pin c is

page_text: withdrawn and the pinion allowed to drop out of gear with the rack into a recess
provided in the lagging C2 within which the apparatus is enclosed.
C³ is an annular chamber formed in the upper part of the base C. 10 is a metallic
plate forming the upper wall of said chamber. The chamber communicates, by several
holes, as e, with the interior of the casing C' for a purpose hereinafter described.
D is the valve seat of the controlling apparatus, the diaphragm A itself forming
the controlling valve. E is a piece of yielding material such as cloth, felt, rubber
or soft leather inserted between the diaphragm and the valve seat. This yielding
material E may be attached directly to the face of the diaphragm, but it will be
found generally more convenient, especially when steam is employed as the operating
fluid, to stretch the strip of yielding material across the valve face. To this end,
it may be secured at one end to a standard e and at the opposite end to a piece e¹
sliding within a standard e² and adjustable from the exterior of the apparatus by
means of a screw e³, a hole being left in the external lagging for this purpose. The
screw e² may be so adjusted that the strip E offers a perfectly even and sufficiently
elastic bed for the diaphragm.
The valve seat is provided with a series of very narrow openings d d', separated
by very narrow strips b as shown in Figures 2 and 5, the size of such openings and
strips being, however, in Figure 5, very much exaggerated. These openings are so
arranged that each alternate one communicates, by a pipe G, with the operating
fluid supply, while the others communicate by a discharge pipe H and trumpet-
mouth H or otherwise, as aforesaid, with the atmosphere. It will thus be seen that
a very minute movement of the diaphragm will be sufficient to unseal the openings d¹
and permit the operating fluid to pass over the narrow strips d² into the adjacent
openings d. The total area for the escape of the fluid being equal to nearly one
half the area of the face of the valve seat and the openings themselves being very
narrow, it will be apparent that a very small movement of the diaphragm will
present a very large area for the escape of the fluid into the pipe H, and yet the
diaphragm will not be unduly strained or bent by the pressure exerted by the
operating fluid.
A valve seat, having two alternating series of very narrow openings separated by
narrow strips as above described may be constructed in a variety of ways. In the
apparatus shown in Figures 1 and 5, the seat is formed by doubling up a metallic
ribbon in zigzag fashion, as shown in Figure 5, the ribbon, when thus folded to leave a
slight space between each two laps, is supported within a suitable casing D'. One
edge of the zigzag ribbon is brought to a true or to a slightly dome-shaped surface,
and forms a bearing face for the diaphragm A and bed E. The opposite edge is
placed upon the bottom of the casing C₁ or other plate serving as an end wall to
the spaces of the ribbon at that edge thereof. The spaces d'x opening out in one
side of the ribbon are connected by slots d³ in the casing D³, to the fluid supply
pipe G aforesaid. The spaces d* opening out from the opposite side of the ribbon
communicate by slots dx with the discharge pipe H and trumpet-mouth H'.
The mode of operation of this form of apparatus is as follows:-
The supply of operating fluid having been turned on, it fills the alternate
spaces d communicating with the valve seat openings d'. The diaphragm is then
nicely adjusted as aforesaid, so that the fluid is just upon the point of escaping
between the face of the valve seat D and the bed E into the casing C. When the
diaphragm is vibrated by the sound vibrations, it compresses the yielding bed at the
forward stroke of each vibration, and, on the return stroke of each vibration, a certain
amount of the operating fluid is permitted to rush into the trumpet mouth H¹,
the absolute amount of fluid passed being small, but large as compared with
the movement of the diaphragm. The fluid rushing into the pipe H and trumpet-
mouth Hat each vibration of the diaphragm produces therein vibrations exactly
corresponding in their form and rate of sequence to the original vibrations, but of
much greater amplitude, so that the resultant sound is much intensified, the amount
of such increase depending largely upon the pressure employed and upon the
number of openings in the valve seat.

page_text: A small amount of the fluid will escape over the edges of the valve seat into the
chamber C. This is, however, led away by a vent pipe c¹² opening into the atmo-
sphere. When steam is employed, any water of condensation collected in the
chamber C¹ is also discharged by the pipe c¹². The steam or other heated fluid
employed has a tendency to heat the diaphragm, and, by causing it to expand at a
greater rate than the base C, it tends to make the diaphragm buckle, so that it does
not respond as readily to the sound vibrations. To obviate this, I provide the steam
chamber C³, as before described, which, communicating with the chamber C¹, by
the holes c, permits the steam to pass to the back of the base C and cause the
latter to expand to about the same extent as the diaphragm. The diaphragm is
thus always kept in a taut condition.
113
Both
In Figure 6, a double arrangement, very similar to the foregoing, is depicted.
In this case, both edges of the zigzag ribbon are utilised as valve seat faces. The
valves are each formed as before by a diaphragm A having a yielding bed E. The
diaphragms are, in this case, shown adjustable by means of a milled rim c¹³ on each
base C. No lagging C2 nor steam jacket C³ is shown, but it should be understood
that such may be applied, if desired. The supply pipe G communicates, as shown,
with the spaces opening out into both the faces of the valve seat, and the discharge
pipe H communicates with the spaces opening out in a similar manner.
bases C are connected by a branched pipe B' with a commou mouth-piece B.
bbare movable collars for connecting the branched mouth-piece to its bases C.
The operation of this arrangement is precisely the same as the one previously
described. As, however, double the amount of vibratory movement is obtained in
the diaphragms that is, double the amount of valve opening at each vibration―
this apparatus is capable of magnifying the original vibrations to a greater extent.
than is the case with the apparatus as shown in Figure 1, other things being equal.
In the arrangement shown in Figures 7, 8 and 9, the face of the valve seat D is
provided with openings arranged on the same principle as those of the seat shown
in Figures 2 and 5, namely, two alternating series of narrow openings communi-
cating respectively with the pressure supply and the trumpet-mouth, and separated
by narrow strips. In this case, however, the openings are arranged concentrically,
the valve seat being, in fact, formed of a series of concentric tubes d' placed at a
very short distance apart and having their adjacent ends faced to form a bearing
surface for the valve F. The width of the spaces dx and d¹× is, for the sake of
clearness, exaggerated in the drawings. One alternate series of spaces ¹× communi-
cates at the end remote from the valve with a chamber G', into which the pressure
supply pipe G opens. The other series d* communicates in a similar manner with
a chamber H2 opening out by the pipe H into the trumpet-mouth H¹.
The valve is formed of a simple disc F, which bears directly upon the valve
seat and may, if desirable, be provided with a slightly yielding face. A is the
primary diaphragm mounted as before upon the base C, which is adjustable upon a
supporting ring and carries a mouthpiece, not shown. The diaphragm is con-
nected with the disc valve F by means of a rod or link J and a lever J', the latter
being pivotted as at j in such manner as to multiply, on the valve, the movement
of the diaphragm. The rod J may conveniently be provided with screwed ends which
pass through holes in the lever and diaphragm respectively, and are provided, at
opposite ends of these holes, with small nuts having rounded bearing faces, as shown.
The action of the apparatus is precisely the same as in the construction
described with reference to Figures 1 to 5.
In order to balance the pressure of the operating fluid on the underside of the
dise valve, the latter is sometimes enclosed in a suitable chamber I supplied with
fluid at such a pressure as will keep the valve perfectly balanced or bearing with
a very slight pressure upon its seat. The pressure in the chamber I may be con-
veniently obtained from the supply pipe G by a branch pipe i provided with an
adjustable pressure reducing device is a drain pipe provided with a cock
and useful, when steam is employed as the operating fluid, for drawing off any
water of condensation which may accumulate within the chamber I.

page_text: The valve lever J passes through an opening in the side of the casing, its
pivot being mounted at or about the centre of the casing wall. Any escape of
the balancing fluid from the chamber past the lever may be prevented by a sleeve i³
of rubber, leather, or other very flexible material surrounding the lever, and
secured at one end thereto and at the opposite end to the adjacent wall of the
casing.
The concentric tube arrangement of valve seat may be also used directly in con-
junction with the primary diaphragm, as in the arrangement shown in Figure 1.
Or the disc valve F may be attached to one end of an extended wire J2 as shown
in dotted lines and operate as hereinafter described with reference to Figures 14
and 15, the wire passing through the central tube dx and through the chamber G
and casing I. Any escape of fluid past the wire may be prevented by the flexible
sleeves It will be obvious that a duplicated arrangement of the apparatus
shown in Figure 7 could be obtained by simply providing the upper side of the
lever J with a second disc valve adapted to bear upon the face of a superposed
valve seat, both valves being provided with yielding beds E and the parts being
so adjusted that both valves bear normally with a light pressure against their beds
as already described with respect to the apparatus shown in Figure 1. In this
case, distinct trumpet-mouths would be used for each valve, and the balancing
pressure chamber I would not be required. If the above duplicated arrangement
were to be operated by an extended wire device such as shown in dotted lines in
Figure 7, the duplicated valve (or its equivalent, a diaphragm with yielding beds
on opposite sides) would be connected to said wire instead of to the lever J.
In the apparatus shown in Figures 10 to 18, the controlling valve F is of a
cylindrical form and bears upon a cylindrical seat D2 surrounding the valve
and forming a casing therefor. The valve may be connected directly or indirectly
to the primary diaphragm in such manner that, at each vibration of the diaphragm,
it receives a slight impulse in an appropriate direction to effect the opening or
closing of the openings in the valve seat. In the apparatus shown, however, the
valve in each case has a sliding movement imparted to it in a line parallel with its
axis, though it will be obvious that it could be so connected to the diaphragm as to
receive an oscillatory or spirally reciprocatory movement.
In the arrangement shown in Figures 10, 11 and 12, the valve F1 bears at one
end against the primary diaphragm A and at the other end against an elastic plate Ja
which serves to keep the valve always in contact with the diaphragm and also
forms one end wall of the discharge chamber H2. are small discs of cloth or
thin leather inserted between the ends of the valve and the diaphragm A and
plate J³ respectively, for the purpose of preventing any jarring between these parts
when vibrated. The diaphragm A. and the elastic plate J³ are adjustable in the
direction of their axis for the purpose of adjusting the valve within its seat. To
this end, they are supported respectively upon bases C J' being each clamped
at the edge between the two annular plates forming the base. The base C carries
the mouth-piece B as aforesaid. Both bases may be conveniently mounted upon
the screwed cylindrical ends of the discharge chamber H2, as shown in Figure 10.
The valve is provided with a series of fine transverse openings or slits fand its
seat is also provided with a corresponding series of slits d'. The valve is so set
that, when the diaphragm is in its normal position, all these slits or ports are just
closed (as shown in Figures 13, 15 and 17) but when the valve is vibrated with the
diaphragm, the ports are opened and closed more or less at each vibration, the
valve being shown in Figure 10 in its fully opened position.
At each vibration of the valve, the operating fluid escapes from the pressure
chamber G through the openings in the seat D' and valve F respectively
into the interior of the valve. Thence it escapes through the open ends of the
valve into the discharge chamber H2 and so by the pipe H into the trumpet-
mouth H¹.
To permit the free passage of the operating fluid past the ends of the valve, the
latter are each provided with light bows or cross pieces f which bear respectively

page_text: against the diaphragm A and elastic plate J'as shown in Figures 10 and 11. hhare
a series of radial arms which serve to support the pressure chamber G¹ within the
discharge chamber H².
In Figure 13, the cylindrical valve F' is shown with one end closed and more or
less rigidly attached to the diaphragm A. by a short stem J, and which may, in
some cases, be of flexible material such as rubber. The other end of the valve
opens directly into the trumpet-mouth H. As in the preceding arrangement, the
operating fluid enters the pressure chamber G¹ by the pipe G and thence passes,
when the valve is operated through the seat openings & and valve openings ƒ into
the interior of the valve and so out into the trumpet-mouth.
In the apparatus shown in Figures 10 and 13, the valve has a slight tendency
(unless it and its seat be very carefully fitted and the latter carefully adjusted with
respect to the diaphragm) to bind on its seat, and so interfere with the ready
response of the valve to the vibrations of the diaphragm. Hence, when a very
delicate and smoothly working instrument is required, it is advisable to attach the
valve to an extended wire or fine rod J2 connected at one end with the diaphragm
and at the other end with a flexible support. Such an arrangement is shown in
Figures 14 and 15, in which the valve F is mounted as before within a cylindrical
seat D². 2 is a bridge piece attached to one end of the valve, the latter being, in
this case, open at both ends. To this bridge piece, a fine wire J2 is attached, one
end of the wire being connected to the centre of the diaphragm A and the other
end to an elastic plate or diaphragm J. For the purpose of adjusting the tension
of the wire and the position of the valve, the ends of the wire may be passed
through small tubes 2, Figures 14 and 16, and connected to the latter by knotting
the wires as at j³. The tubes are screwed and provided with nuts bearing on the
outer faces of the diaphragm and plate respectively. The ends of the valve open
directly into the short pipes H of the trumpet-mouths in a similar manner to the
apparatus shown in Figure 13. G'is the pressure chamber, provided with a supply
pipe G. As before, the entire apparatus is shown mounted upon a rough wooden
frame K, this being the form used in my original model. K'K' are guard plates
used to prevent the magnified vibrations issuing from the trumpet-mouths from
interfering with the vibrations of the primary diaphragm and with the corre-
sponding vibrations of the spring plate. In some cases, it is advisable to mount
the diaphragm and valve seat or one of them upon supports of lead or other heavy
inert material, in order to prevent undue vibrations being imparted to the valve
through the supporting framework.
In order to ensure that the valve shall work perfectly smoothly and freely
within its seat, the wire J² and valve are lined up in the following manner :-
Fine perforations are made at the centres of the diaphragm A, spring plate J
and bridge. One or more of the above pieces are then adjusted until the three
perforations are brought into accurate alignment as found by sighting through
them from one end. The parts are then secured in position and the wire is then
threaded through the perforations, tightened up & adjusted.
It
In all the cylindrical valves and valve seats above described, the openings or
slits are made as fiue as possible. They may be conveniently formed by
temporarily fastening the valve and its seat together and sawing through them
both. To facilitate this sawing operation as well as to impart additional rigidity
to the seat, it is sometimes preferable to form the latter of comparatively thick
metal, as shown in Figures 17 and 18, and to turn on its periphery a series of deep
tapering grooves do, having a similar pitch to the openings to be formed, and to
then saw through the material intervening between the bottoms of the grooves and
the interior face of the valve.
In the arrangements hereinbefore described, the valve seat has been an absolutely
stationary piece. It will be obvious, however, that it may only be a relatively
stationary piece. An arrangement of this kind is shown in Figure 19. F' F' are
two cylindrical slitted valves sliding one within the other and each forming a seat
for the other. Each valve is attached by a bridge piece f' and stem J' to a

page_text: diaphragm A, the two diaphragms forming the end walls of the discharge chamber
as in Figure 10 and being provided with a branched mouthpiece as in the
arrangement shown in Figure 6.
In operation, the operating fluid passes from the supply chamber G' through
the openings in the two cylindrical valves, out at the open ends of the valves
and thence by the discharge chamber and discharge pipe into the trumpet
mouth.
In all the arrangements previously described herein, the sound vibrations are
transmitted to the controlling valve through the medium of a vibratory diaphragm.
In Figure 20, however, an arrangement is shown in which the sound vibrations act
directly upon the valve itself. B is the mouthpiece which opens into a vertical
speaking tube B². F₁ is the valve which is of the slitted cylindrical type and has
one end closed. The closed end works loosely within the end of the tube 132,
its area being, if necessary, extended to the size of the tube by an annular flange f
The valve is upheld in position by an adjustable rod J which rests upon a rubber
tip on the end of the valve. is a cross stay having a bearing for the rod J.
The sound vibrations entering the tube B' impinge directly upon the end of the
valve and vibrate it as before described. The valve is returned into its normal
position at each vibration by its own weight or by a light spring connected to it
in any convenient inanner. This latter arrangement of apparatus, although it does
act to a certain extent, does not give very satisfactory results, and I do not
recommend it as a practical working apparatus.
It will have been noted that the narrow openings in the valve seats and valves
hereinbefore described are arranged in a comparatively small area, and in such
manner that they present a much extended edge over or past which the operating
fluid may escape at each vibration of the valve. It will be obvious, however, that
it is not absolutely essential that a numerous series of openings should be employed,
as the valve seat could be constructed with one or a few narrow openings so
diverted, zigzagged or coiled as to present, within a comparatively small area, a
much extended edge over or past which the operating fluid could escape as above
described. An example of such a form of valve seat is depicted in Figure 21, in
which D is the valve seat having in its face a single narrow opening d¹ for the
fluid supply and two openings for the discharge. The opening d extends in a
zigzag manner across the face of the seat, and presents a very extended edge past
which the fluid may escape through the openings d and pipes H to the discharge
orifice. The valve seat is formed, in a somewhat similar manner to that shown in
Figures 2 and 5, by two stiff zigzagged ribbons placed one within the other at a
short distance apart, and provided with distance pieces, if necessary. As before, the
edges of the ribbons form the face of the seat. The zigzagged space between the
ribbons leads from the opening d in the face of the seat to a chamber Gat
the opposite end of the seat which is supplied with the operating fluid by a pipe G.
Figure 22 shows how the magnified vibrations or impulses may be transmitted
indirectly to the air through the medium of a large secondary diaphragm L. This
diaphragm may conveniently be placed across the enlarged end of the trumpet
mouth H' as shown. The successive puffs of the escaping fluid strike the diaphragm
and vibrate it in accordance with the original vibrations, any accumulation of
pressure within the trumpet mouth being prevented by a series of holes or openings
which permit the fluid to escape after having impinged upon the diaphragm. The
diaphragm may, if desired, be connected to a second and larger controlling valve,
as shown in dotted lines in Figure 22, or to one of the frictional devices hereinafter
described.
In Figure 23 there is shown a modified form of apparatus in which the magnified
vibrations or impulses are transmitted indirectly to the air by a large secondary
diaphragm L. A is the primary diaphragm and F the valve connected therewith
by a post J bearing at its ends upon the valve and diaphragm respectively. The
valve is a simple disc, by preference, faced on both sides with a slightly yielding
material such as cloth or thin leather. The disc F bears lightly against the faces

page_text: of two opposing perforated valve seats D D, one of which communicates with the
supply pipe G and the other with the atmosphere. The valve seats are provided
respectively with a series of small holes d d each of which is surrounded at the
face of the seat by a narrow bearing strip as shown on an enlarged scale in
Figures 234 and 23B. It will be seen that, the aggregate of the bearing rings d
being taken, this construction of seat offers a very extended and narrow edge
past which the operating fluid may freely escape at each minute movement of
the valve into or out of the chamber H2 containing the valve. This construc-
tion also has the advantage that it permits the operating fluid to act upon a
large portion of the area of the back of the disc F, when the latter is pressed
against the seat D remote from the supply pipe G, thus reducing the force
necessary to operate the disc and rendering its action more sensitive. are guide
pins for retaining the valve in position. One side of the chamber H2 is cut
away at H³ and furnished with a large secondary diaphragm L. is one of a series
of grooves formed in the side of the chamber for the purpose of facilitating
the flow of the operating fluid towards the diaphragm L. The pressure of the
valve on the valve seats may be regulated by screwing one of the seats as at d
into the side wall of the chamber. The position of the diaphragm A with
reference to the valve may be regulated as before described. At each vibration
of the primary diaphragm the pressure in the chamber H2 is alternately decreased
and increased by reason of the holes d and d being alternately more or less opened
or closed to the atmosphere and supply pipe respectively. This rise and fall of
the pressure in chamber H2 causes the secondary diaphragm L to be vibrated, the
vibrations having the same form and rate of sequence as those of the primary
diaphragm but a greater amplitude. The diaphragm L is, by way of illustration,
shown connected with a friction sound-magnifying apparatus, as seen in dotted lines
and hereinafter described with reference to Figure 26, the said diaphragm acting as
primary diaphragm to said apparatus.
In Figure 24 an apparatus is shown in which the operating fluid employed may
be a liquid, as, for instance, water. In this case, the openings d in the valve seat D
are normally open, and the vibrations of the primary diaphragm A so act upon
the controlling valve F2 as to close these openings to a greater or less extent, at
each vibration of the said diaphragm. G2 is a reservoir supplying the operating
fluid under a sufficient head or pressure. G is the supply pipe. The valve seat D
which is in the form of a perforated plate is placed transversely at the end of the
supply pipe G. H is the discharge pipe leading from the valve seat. The operating
fluid flows continuously through the small openings d in the valve face.
The valve F2 is formed of a flat plate or disc, located directly opposite to the
valve face. The valve is connected with the diaphragm in any appropriate manner
which will permit of it moving in a direction parallel with the face of the valve
seat and also, to a slight extent, in a direction at right angles thereto. To this
end, the valve may be conveniently attached to the centre of the diaphragm by a
rod J having a slightly flexible portion which permits of a small lateral move-
ment in the valve. The openings in the valve correspond exactly with those in the
valve seat and may be so adjusted that the operating fluid can flow continuously
through both the seat and the valve without in any way affecting the latter. On
the primary diaphragm being vibrated, the valve closes the openings in the seat
more or less at each vibration, and the impact of the operating fluid against the
valve imparts to it vibrations having the same form and rate of sequence but a
much greater amplitude than the original vibrations.
The valve is connected by any suitable device, such as a stem J', (which, by
preference, rests with one end against the back of the valve) with a large secondary
diaphragm L so that each vibration imparted to the valve by the impact of the
issuing fluid is transmitted to said secondary diaphragm, the vibrations of the latter
being of a much greater amplitude than those of the primary diaphragm. The
secondary diaphragm may be provided with a trumpet mouth H.
The primary diaphragm A is adjusted by means of a sleeve c" having its ends

page_text: provided internally with right and left hand threads adapted, respectively, to mesh
with corresponding threeds upon the supporting ring C+ and mouth piece base C.
e is a pin, which projects from the base C into a recess c formed on the
supporting ring C and serves to prevent the diaphragm turning about its axis
during the adjustment, and thus placing the valve out of parallel with the valve
seat.
is a device for adjusting the length of the stem j. The latter passes through
a hole in the discharge pipe, said hole being a loose fit for the stem. On the
exterior of the pipe surrounding this hole is a pocket 3 into which any fluid leaking
past the stem finds its way. The hole through which the stem passes in the outer
end of the pocket is provided with a conical flexible sleeve such as has already
been described with reference to Figure 7. This sleeve prevents any possibility
of leakage past the stem and does not interfere with the free movement of the
latter.
is a pipe connecting the bottom of the pocket h³ with some point in the
discharge pipe below the pocket. Its vocation is to draw away any water entering
the pocket past the stem, and its size is such as to prevent any pressure of fluid
within the pocket, as such pressure would act detrimentally to the responsive
vibration of the secondary diaphragm, by exerting a pressure on the stem through
the medium of the flexible sleeve. It will be seen that, by the above arrange-
ment, the steni can nove with perfect freedom and it is not in any way affected by
the pressure or flow of the operating fluid in the discharge pipe H through which
it passes.
In Figure 244 an arrangement slightly differing from the preceding is shown.
In this, the valve face D is attached to the stem J' of the primary diaphragm and
is connected by a short flexible tube g with the supply pipe G in such manner that it
may vibrate freely with the diaphragm. The valve F is attached to the end of the
rod J and vibrates with the secondary diaphragm. The action of the apparatus is
the same as that shown in Figure 24.
Figure 25 is an enlarged section of a portion of the valve seat and valve,
and shows the form of openings which I prefer in the valve seat. It will be
understood that the distance of the valve from the face of the valve seat is somewhat
exaggerated, it being only necessary to have such a space between the two as shall
permit of the secondary diaphragm vibrating freely.
With some forms of the apparatus, especially those having a cylindrical slitted
valve as described, it will be sometimes found advisable to filter the operating fluid
before passing it through the valve, as a very slight amount of impurities lodged
about the openings in the valve and its seat is sufficient to interfere with the free
working of the valve.
By the words "fluid under pressure" is to be understood a fluid having an
absolute pressure greater than that of the fluid in the discharge pipe or chamber,
which communicates through the controlling device with the pressure supply.
"Pressure" being only a comparative term, it will be obvious that the absolute
pressure in the supply pipe or chamber may be equal to, or even less than, atmo-
spheric pressure, it being only necessary in this case to maintain in the discharge
pipe or chamber a partial vacuum of an amount sufficient to produce the required
difference of pressure between the fluids in the two pipes or chambers. Moreover,
a partial vacuum could be maintained in any case in the discharge pipe or chamber
with the object of increasing the difference of pressure as aforesaid and thus
increasing the power of the apparatus. Also a partial vacuum could be main-
tained in the supply chamber, the fluid in the discharge pipe or chamber being at
atmospheric pressure. In this case, the operation of the fluid controlling device is
reversed, the supply chamber becoming in fact the discharge chamber and vice versa.
For example, in the arrangement shown in Figures 10 and 12, the fluid would, on
the vibration of the diaphragm, pass from the pipe H and chamber H2 to the interior
of the valve, and thence through the valve and valve seat to the chamber G¹ and
pipe G, the latter being provided with a trumpet mouth,

page_text: The principle upon which the various apparatus shown in and described with
reference to Figures 26 to 36 is constructed, consists in causing the original
sound vibrations, acting directly or indirectly through the medium of a vibratory
body, to so vary the co-efficient of friction between a body moving in a constant
direction and a piece movable with a vibratory diaphragm, as to govern the
application of the motive power of said moving body to the diaphragm, or its
equivalent, in such manner that there is set up in the latter a series of vibrations
having the same rate of sequence as, but of a much greater amplitude or magnitude
than, the vibrations to be magnified. Sounds may thus be produced having the same
pitch, and more or less of the same quality, as the original sounds, but having a much
greater intensity or magnitude.
It
In applying this principle to the construction of practical working apparatus, the
vibrations to be magnified are transmitted by suitable means to a vibratory diaphragm
or other suitable vibratory body, hereinafter called the "primary diaphragin.
a convenient position with respect to the latter, there is arranged a moving body,
having either a curved or rectilinear motion in a constant direction, and hereinafter
called the "motive body." At a suitable distance from the motive body there is
mounted a second vibratory diaphragın, preferably a larger one, hereinafter called
the "secondary diaphragm." A piece movable with the secondary diaphragm, and
connected to it in any suitable manner, bears lightly upon the surface of the motive
body. The primary diaphragm is connected, by any suitable means, with the
aforesaid piece, at or about its point of contact with the motive body, in such
manner that each vibration imparted to the primary diaphragm varies the co-efficient
of friction between said piece and motive body, and so causes the latter to exert an
increased or diminished momentary pull or push on the piece.
The secondary
diaphragm, bearing piece and its connections are preferably so arranged with respect
to the motive body that the said push or pull is transmitted to the diaphragm in a
direction more or less perpendicular to its surface.
Other vibratory bodies may, as hereinafter described, be substituted for the
secondary diaphragm.
Figure 26 is a vertical section of one form of apparatus constructed on the lines
just described.
Figure 27 is a modification of the preceding apparatus.
Figures 28 and 29 are plan and elevation, respectively, of another modified form
of apparatus.
Figure 29 shows another form of the wheel seen in Figure 28.
Figure 30 shows in horizontal section another form of apparatus.
Figure 31 is a section on line W W, Figure 30.
Figures 32 and 33 are enlarged end elevation and sectional plan respectively of a
portion of the apparatus shown in Figures 30 and 31.
Figure 34 is a plan showing another modified form of the apparatus.
Figures 35 and 36 are transverse and longitudinal section respectively of an
arrangement in which the primary diaphragm is dispensed with.
Referring first to Figure 26 :-
A, is the primary diaphragm mounted upon a base C, which is provided with a
mouthpiece B and is adjustable as at e' upon the supporting ring C
M is the
motive body which, in this case, is a wheel or disc mounted upon a shaft M'. The
wheel has, by preference, a flat periphery and is caused, by any suitable extraneous
force, to revolve in a constant direction. L is a large secondary diaphragm mounted,
in this instance, with its axis at right angles to that of the diaphragm A, and
provided, at its side remote from the wheel, with a trumpet mouth H'. N is a thin
Hat strip of any suitable material projecting perpendicularly from about the centre
of the secondary diaphragm L and bearing, at or near its outer end, upon the
periphery of the wheel M, with respect to which it is arranged more or less
tangentially. The strip N is slightly flexible in a direction to and from the
periphery of the wheel M, being made of elastic material or connected in a
flexible manner to the diaphragm L, as by a section of rubber. The diaphragm A

page_text: is located with its centre approximately opposite the point of contact of the
strip N with the wheel M, and a short post or stem P extends from about the
centre of the diaphragm to the side of the strip opposite its said point of contact.
The post P may be connected to the diaphragm A in a slightly flexible manner, as
by a section of rubber, or it may be provided with pointed ends as shown, adapted
to enter respectively into a small indentation in the strip M and in a button a on
the diaphragm.
The diaphragm A is so adjusted upon its supporting ring C₁ that the strip N is
pressed lightly against the wheel M. The slight friction thus set up between the
wheel and strip causes the latter to exert on the diaphragm L a slight pull-or
push, if the wheel be rotating in the opposite direction-sufficient to keep the
diaphragm and strip in a taut and sensitive condition. In the position of rest, the
co-efficient of friction between the wheel and the strip and the consequent pull (or
push) on the diaphragm L remain constant, though comparatively slight. When,
however, the primary diaphragm A is vibrated, its varying vibrations are trans-
mitted to the strip N, thus increasing the friction between it and the wheel to a
correspondingly varying extent, and so varying the force of the pull on the
strip as to set up in the diaphragm L a series of vibrations having the same
rate of sequence and more or less the same form as those of the diaphragm A,
but of much greater amplitude. It will be understood that the momentary
diminutions of friction occurring on the return movements of the primary
diaphragm permit of corresponding return movements in the secondary diaphragm
by virtue of its elasticity.
Various devices may be employed for increasing the friction between the motive
body and the piece connected with the secondary diaphragm. For example, the
bearing surface of either or both of the said parts may be coated with wash leather,
paper, resin, oil, dust or the like, or the surface or surfaces may be roughened
or grooved in a suitable manner.
Or the strip N may be bent round a portion of the periphery of the wheel, as
at n, Figure 27, so that the diaphragm A and post P operating on its extreme end,
as at n', tend to draw it round the periphery of the wheel. This action may be
still further increased by placing the diaphragm A and post P at an acute angle to
the bar N, as shown in dotted lines in Figure 27.
Or the bearing piece N and post P may be in the form of a number of wires N¹,
Figures 28 and 29, which may be stretched between the primary diaphragm A.
and the secondary diaphragm L, and a grooved revolving wheel M may be so
located with respect to the wires and diaphragms that the wires are bent partly
round its periphery. The grooves in the wheel, being very small, are not shown
on Figure 28. I prefer, in this case, to make the wheel M stepped as in Figure 29ª,
as by this means I can use wires of different lengths and I then find that the
diaphragm L responds more accurately to the various kinds of vibrations set up
in the diaphragm A. The tightening and slackening of these wires, due to the
vibrations of the primary diaphragm, increase and diminish the friction between the
wheel and each wire, and so set up in the secondary diaphragm corresponding
vibrations of greater amplitude, as before described.
Figures 30 to 33 show another arrangement, in which the friction is still further
increased. N2 is a laminated bundle of thin strips N of paper, mica, wood, metal
or other suitable material, which is attached at one end to the centre of the
secondary diaphragm L. The shaft M', revolving in the direction of the arrow,
Figure 32, is mounted upon a frame K2, with its axis at right angles to the
bundle N2. On the shaft is a wheel M formed of a series of circular discs M² of
paper or other thin and sufficiently flexible material. The free ends of the strips N
and those portions of the disces M2 which are turning away from the secondary
diaphragm are interleaved, as seen in Figures 30 and 33, one disc being placed
between each two strips and the latter lying more or less tangential to the path of
revolution. A A are a pair of adjustable primary diaphragms furnished, on their
outer faces, with a branched mouthpiece B B', and connected on their inner faces,

page_text: by light posts P, with the free ends of the outermost strips N, the ends of the posts
being pointed and inserted into indentations in the adjacent parts, as herein before
described with respect to Figure 26. The diaphragm supporting rings C* are
carried on the frame K2, as shown.
The diaphragms, being thrown into a state of vibration, will alternately compress
and relax the interleaved strips and discs, so that the co-efficient of friction between
a great number of surfaces is varied and the power of the apparatus thereby largely
increased.
In order to limit the surfaces of contact as much as possible to those parts of the
dises which are moving in a path more or less parallel with the strips, the ends of
It is
the latter are provided with small bearing discs n² of thin paper or the like.
preferable to form the outermost strips, as shown, of somewhat stouter material,
such as thin wood. The thickness of the discs M², strips N, and discs n² is much
exaggerated in Figure 33.
Figure 34 shows an apparatus in which the motive body is in the form of a
travelling endless band, cable or wire M³ mounted upon guide rollers M*. NN are
a pair of laterally flexible strips attached to the centre of the secondary diaphragm L
and bearing at their free ends against opposite sides of the band M³, the said ends
being preferably curved transversely, as shown at n³, to afford a greater bearing
surface. is a bridge piece serving as a lateral stay to the two strips N.
two primary diaphragms connected to the strips by posts P, as in the arrangement
shown in Figure 30, the operation of the apparatus being the same as herein-
before described.
A are
The tube N is
In some cases, I may dispense with the primary diaphragm entirely and cause
the sound vibrations to act directly upon one of the parts, the friction between
which is to be varied. An apparatus of this description is shown in Figures 35
and 36. M is a thin, slightly flexible metallic tube closed at one end and capable
of rotation about its axis in a constant direction. M' is the shaft carrying the
tube. m are the shaft bearings and m³ the driving pulley. B is the mouthpiece,
the inner end of which overlaps the open end of the tube, without, however,
impeding its movement. N is a rigid tube surrounding and closely fitting the
tube Ms and capable of oscillating thereon to a limited extent.
furnished with an arm N° which is connected by a link N' with the large secondary
diaphragm L. The inner tube M5 in its rotation tends to rotate the outer tube N
and exert a pull on the diaphragm L. On speaking into the mouthpiece B, the
walls of the thin tube M5 are caused to vibrate laterally and the friction between
its outer surface and the inner surface of the tube N is varied in accordance with
such vibrations. The power exerted by the rotating tube upon the diaphragm L
is thus correspondingly varied and the diaphragm is vibrated in accordance with
the sound vibrations entering the mouthpiece B and gives forth corresponding
vibrations on a magnified scale. The dotted lines at the left of Figure 10 show
how the apparatus may be connected with a second diaphragm L acting in unison
with the first.
It will be obvious that the preceding arrangement could be reversed, the outer
tube being rotated and the inner one connected to the diaphragm L.
It will be generally found most advantageous to so mount and drive the motive
body that the active part of its surface shall move away from the secondary
diaphragm in a direction at right angles thereto. It will be obvious, however,
that, by connecting the bearing strip or strips N with the secondary diaphragm by
means of suitable mechanical transmitting devices, the motive body may be
arranged in any convenient position with respect to the said diaphragm.
It will be obvious that the original sound vibrations may be transmitted
indirectly to the primary diaphragm or equivalent vibratory body, through the
medium of a telephonic transmitter in the well known manner, or through the
medium of a phonograph record-cylinder or the like.
The secondary diaphragm or equivalent vibratory body may be employed for
reproducing the magnified sounds directly by a trumpet mouth H', or the magnified
C

page_text: vibrations may be transferred to the recording surface of a phonograph or similar
instrument, or they may be employed to work the valve of a sound magnifying
apparatus such as hereinbefore described with reference to Figures 1 to 25.
The principle upon which I construct the various apparatus shown in-and
described with reference to Figures 37 to 51 consists in transforming the sound
vibrations to be magnified into a corresponding series of electrical vibrations or
impulses, passing such impulses through an electro-magnetic device capable of
creating or varying a magnetic field (or fields) in accordance with said impulses,
permitting such magnetic field to offer correspondingly varying amounts of retarding
force to the movement of an electric conductor passing through it in a constant
direction and driven by an extraneous power, and transmitting, to a suitable
vibratory diaphragm, successive portions of said extraneous motive power varying
in accordance with the power absorbed in overcoming the said varying amounts of
retarding force.
In applying this principle to the construction of practical working apparatus,
the vibrations to be magnified are transformed into a corresponding series of
electrical vibrations or impulses by means of a suitable electro-magnetic or variable
contact device, such as a telephonic transmitter. These electrical impulses are
then caused to circulate through the coils of one or more electro-magnets, preferably
of the horse-shoe type, which may be permanently magnetised or otherwise, whereby
a magnetic field (or fields) is (or are) created or varied in intensity. The strength
of this magnetic field varies in accordance with the impulses passing through the
coils. An electric conductor, driven by any suitable extraneous force, in a constant
direction and moving in either a curved or rectilinear path, is so mounted with
respect to the magnet or magnets that the whole or a portion of it passes through
the magnetic field. The magnetic field opposes, to the movement of the conductor,
a certain amount of retarding force, varying with the variations in the field.
Either the magnet or the conductor is mounted upon or otherwise made movable
with a secondary diaphragm or similar vibratory body. The various parts are
preferably so arranged that the moving conductor, or some part movable there-
with, normally exerts a constant, though generally very slight, push or pull upon
the diaphragm in a direction more or less perpendicular thereto. Momentary
variations in the amount of the aforesaid magnetic retardation cause corresponding
momentary variations in the force of said push or pull, with the result that there
is set up in the diaphragm a series of vibrations corresponding to the electrical
vibrations or impulses passing round the coils of the magnet. By properly pro-
portioning and arranging the apparatus, there may be set up in the diaphragm
vibrations exactly corresponding to, but of a much greater amplitude than the
original sound vibrations. Sounds may thus be produced having the same pitch
and more or less of the same quality as the original sounds, but having a much
greater intensity or magnitude than the latter, or than the sounds which would
have been produced had the magnet been applied directly to the secondary
diaphragm as in a telephonic apparatus.
Other vibratory bodies may, as hereinafter described, be substituted for the
secondary diaphragm.
Figures 37 and 38 are side elevation and plan respectively of a type of apparatus
in which the electric conductor is in the form of a revolving disc, the magnet not
being shown in Figure 38.
.
Figure 39 is a front elevation of the apparatus shown in Figures 37 and 38, parts
of the driving mechanism being removed.
Figures 40 and 41 are views, similar to Figures 37 and 39, showing a reversed
arrangement of the preceding apparatus,
Figure 42 is a side elevation of an apparatus in which the conductor is in the
form of an endless travelling band.
Figure 43 is a section on line V V, Figure 42.
Figures 44 and 45 are respectively elevation and sectional plan of a reversed
arrangement of the apparatus shown in Figures 42 and 43,

page_text: Figure 40 is a section on nine
Figure 44.
Figure 47 shows, in side elevation, a modified arrangement of the apparatus seen
in Figure 44.
Figure 48 is a section on line T T, Figure 47.
Figure 49 is a side elevation, and
Figure 50 a rear elevation, with parts removed, of a form of apparatus in which
the electric conductor is a continuous jet of liquid.
Figure 51 is a side elevation showing a reversed arrangement of the apparatus
seen in Figure 49.
Referring first more especially to Figures 37, 38 and 39:-
Qis an electro magnet, round the coils 7 of which the electric impulses from a
telephonic transmitter or similar device are caused to circulate. 7 are the
connecting wires for the coils. The magnet is mounted upon a fixed base K³.
This magnet may be polarised, if desirable, by a steel polariser placed in its
neighbourhood or by causing a uniform current of electricity to circulate round the
coils
R is an
99, or round an independent coil or coils wound on the same core.
electric conductor which may be in the form of a sphere or of a circular disc, as
shown, and is preferably of copper. The disc R is mounted upon a shaft r in such
manner that the poles of the magnet embrace the disc, as seen in Figure 39.
The disc R is rotated in a constant direction and at a more or less uniform speed
by any suitable means as by pulleys on its shaft, light smooth bands ², and
driving pulleys ³ operated by an extraneous force. is a bracket supporting the
conductor shaft r and attached, either rigidly or by stout blocks of india rubber, to
the secondary diaphragm L, or similar vibratory body, preferably at or about its
centre. Only a portion of the diaphragm is shown, but it is to be understood that
its size relative to the other parts of the apparatus is much larger than is depicted
in the drawings, and that it is supported in any manner which will permit of it
vibrating freely. Two sets of driving pulleys and bands are employed, as shown,
one on each side of the disc R, in order that the latter may run smoothly and not
impart undue vibrations to the diaphragm. The relative positions of the parts and
the direction of rotation are preferably such that the pull on the diaphragm acts
along lines more or less perpendicular thereto.
The operation of the apparatus is as follows:
The tension of the bands, or the speed of rotation, or both, is preferably so
adjusted that the bands exert normally a slight but uniform pull upon the diaphragm
sufficient to maintain the latter in a taut and sensitive condition. The electric
impulses, circulating round the coils q make, by means of the magnet, a magnetic
field whose strength varies as the force and duration of said impulses. The
variations in the magnetic field offer correspondingly varying amounts of retarding
force to the rotation of the conductor disc R, and thus cause to be applied to the
diaphragm similarly varying amounts of the motive power of said disc. In other
words, the force of the pull of the bands upon the diaphragm is varied in exact
accordance with the impulses passing around the magnet coils, with the result that
there is set up, in the diaphragm, a series of vibrations similar to the original
sound vibrations. The parts are so proportioned that the diaphragm reproduces
the original vibrations in a magnified degree, or produces vibrations having a
greater amplitude than would have been the case had the magnet been applied
directly to the diaphragm after the manner of a telephonic receiver.
In the apparatus shown in Figures 40 and 41, the electro magnet Q is mounted
upon the diaphragm L, and the disc R and its shaft are mounted upon a stationary
support in proximity to the diaphragm. The action of the apparatus is the same
as that previously described, the varying retardation offered to the movement of
the disc re-acting through the magnet to vibrate the diaphragm.
In Figures 42 and 43, the conductor is shown as an endless travelling band R'
supported at one end upon the pulley r', which is mounted upon the bracket
attached to the diaphragm. The opposite end of the band is supported upon the
driving pulley. The maguet Q is mounted upon a support, independent of the

page_text: diaphragm, and the band R¹ passes between its poles as shown, the action of
the magnet on the band being similar to that of the magnet on the disc R
aforesaid.
In the modified arrangement shown in Figures 44, 45 and 46, the magnet Q is
attached to the diaphragm, and the band conductor R is mounted independently of
the diaphragm and runs between the poles q² of the magnet which are hollowed
out, as shown in Figure 46, to embrace the conductor, the latter having, in this
case, a circular cross section.
Figures 47 and 48 show a very similar arrangement in which the magnet Q,
instead of being attached directly to the diaphragm, is attached by a laterally
flexible stem q³ to the fixed support K³ in such manner that it can be vibrated as
in the case of the magnet shown in Figure 44 in accordance with the electric
impulses circulating round its coils. The vibrations of the magnet are transmitted
indirectly to the diaphragm by any suitable mechanical device, such as a post N³,
the ends of which are pointed, as shown, and rest, the one end within an indentation
in a button on the diaphragm and the other end within an indentation in a cross
piece q on the magnet.
The apparatus shown in Figures 49 and 50, is the same as that just described,
with the exception that the solid band conductor r¹ is placed by a liquid conductor R²
in the form of a continuous jet, preferably of water, which is projected between the
hollowed out poles of the magnet, as in the case of the travelling band R. is
the water supply pipe provided with a nozzle 6, and 7 is a funnel to receive the
water after it has passed the magnet and convey it to the discharge pipe.
In Figure 51 a reversed arrangement of the preceding apparatus is shown, in
which the magnet Q is fixed and the funnel is movable being connected to the
discharge pipe by a flexible section and to the diaphragm by the post N³.
The secondary diaphragm L, when employed for reproducing the magnified
sounds directly, may be provided with a trumpet mouth of any suitable shape.
The magnified vibrations of the diaphragm may be transferred to the recording
surface of a phonograph or similar instrument, or they may be employed to work
the valve or frictional device of sound magnifying apparatus such as hereinbefore
described with reference to Figures 1 to 36. In many cases, two or more of the
apparatus hereinbefore described may be worked in series.
The word "diaphragm," employed hereinbefore, is to be understood as embracing
any solid body so constructed and arranged as to be capable of being vibrated by
sound vibrations transmitted to it either directly or indirectly by mechanical,
electrical or other agency.
In many of the above forms of apparatus, which are actuated by means of a
diaphragm, it is sometimes advisable that the diaphragm should give off its
vibrations through a light spring or section of india-rubber. The shape of the
mouthpiece employed with the primary diaphragm will vary according to the nature
of the sounds to be dealt with.
The following are a few of the objects to which the invention is applicable :-
It is applicable as a telephonic receiver or relay and as an auxiliary to a
transmitter in telephonic apparatus, the primary diaphragm, where such is employed,
being provided with a small magnet which is acted upon in the well known manner
by the electric impulses produced by the telephone.
It is also applicable in a similar manner as a sensitive receiver for telegraphic
or other electric signals or impulses.
It is also applicable as a telegraphic relay, the weakened electric impulses being
utilised to vibrate the secondary diaphragm in any of the ways hereinbefore
described. The said diaphragm then becomes a primary diaphragm to transmit
the magnified impulses to the succeeding section of the electric line after the
manner of a telephonic transmitter.
It is also applicable as an adjunct to a phonograph, graphophone or similar
instrument, by means of which both the impressions and reproductions may be
strengthened. The impressions may be strengthened by causing the original sound

page_text: to be intensified by means of one of my apparatus before it is delivered to the
phonograph or like instrument. The reproductions may be strengthened by
connecting the valve, frictional device, or primary diaphragm of one of my apparatus
with the recording surface of the instrument in any well known manner, the said
diaphragm, frictional device, or valve being in fact vibrated by the recording
surface instead of by the original sound which has been recorded.
The invention is applicable as an apparatus to assist in forming permanent
records of sonorous or other vibrations, in which case the magnified vibrations may
be dealt with instead of the original ones in the ordinary manner, or the secondary
diaphragm aforesaid may be connected directly to the recording instrument.
It is applicable as a speaking apparatus by which one or more individuals can
speak or sing to large audiences :
As a means of enabling the one in command to make his orders heard either on
board ship, on the battle field, at fires, or in any place where the ordinary voice
would not be distinguished;
And as an apparatus by which, in foggy weather, or at night, or otherwise, one
ship can speak to another, or a person, or phonograph or other like instrument, can
shout the name of a lighthouse or other information or sound to be heard at very
great distances.
It is also applicable as a means of communication from or between moving
carriages or trains ;
And for the purpose of increasing, variably or otherwise, the volume of sound
emitted by bells an organ, or other musical instrument or instruments, thereby
avoiding the necessity of securing great power in designing such instruments. For
increasing the sound in a variable manner (in cases where the fluid pressure type
of apparatus is used) pressure regulating devices may be employed whereby the
pressure in the supply chamber may be varied at will. Or any of the apparatus
hereinbefore described may be provided in multiple, one or more of them being
brought into action as required. Or the original sound may be more or less
screened from the primary diaphragm. It is not necessary that the whole of the
musical instrument, or indeed any part of it, should be placed in the building in
which the magnified sounds are to be heard, for, by means of one or more sounding
tubes, solid rods, or electric wires, the sound may be conveyed from the instrument
or certain departments thereof to the magnifiers, which will themselves be placed
within the building.
In an organ, the swell box need not be provided with shutters, for the transmitting
part of the apparatus may be placed in a small box with variable opening within
the swell organ, and a most wonderful crescendo or diminuendo can be thus
obtained.
The invention may also be used as a means of increasing the efficiency of speaking
tubes.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an apparatus for reproducing sonorous vibrations with increased amplitude
by controlling the flow or emission of a fluid under pressure in accordance with the
vibrations to be magnified, a fluid controlling device operated in accordance with
said vibrations and having a series of small or narrow discharge openings, or one
or more narrow openings diverted, zigzagged or coiled in such manner as to present
within a limited area a much extended edge over or past which the effluent fluid
may escape, whereby, at each minute vibration of the movable member of said
controlling device, a comparatively large area is opened or closed for or against
the escape of the fluid, substantially as described.
2. The method of reproducing sonorous vibrations with increased amplitude,
which consists in causing such vibrations to govern the application of an extraneous
force to a vibratory diaphragm, or equivalent vibratory body as described, by

page_text: varying, directly or by mechanical means, the friction between two or more surfaces,
one (or more) of which is driven in a constant direction by said extraneous force,
and one (or more) of which is acted upon, directly, or through a mechanical device,
by the actuating vibrations, substantially as described.
3. The method. of reproducing sonorous vibrations with increased amplitude,
which consists in transforming such vibrations into a corresponding series of
electrical vibrations or impulses, passing such impulses through an electro-magnetic
device capable of creating or varying a magnetic field (or fields) in accordance
with said impulses, permitting such magnetic field (or fields) to offer correspondingly
varying amounts of retarding force to the movement of an electric conductor passing
through it (or them) in a constant direction and driven by an extraneous power,
and transmitting to a suitable vibratory diaphragm or its equivalent as described
successive portions of said extraneous power varying in accordance with the power
absorbed in overcoming the said varying amounts of retarding force, substantially as
described.
4. The various forms of apparatus, each taken as a whole, substantially as herein
described and illustrated and for the purpose herein set forth.
Dated this 25th day of June 1801
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.