Year: 1885

page_text: I SILVANUS PHILLIPS THOMPSON of 20 Arundel Gardens Notting Hill in the
County of Middlesex Doctor of Science and Professor of Experimental Physics
do hereby declare the nature of this Invention to be as follows:-
My improved instruments are designed chiefly for increasing the power of
telephonic transmission and embody several new features of construction and a
new method of working-A very large number of small and light microphones are
arranged in parallel arc and capable of being tested and adjusted either singly or in
groups. They are supplied with current either singly or in groups from a battery
or batteries and where fewer batteries are employed than microphones resistances
may be introduced to equalize their action. These microphones are so arranged
that the vibrations of the voice are simultaneously imparted to the whole of them
or to the contact points of the whole of them at the same instant either directly or
by means of a suitable diaphragm or diaphragms or by a suitable tube or tubes
and a convenient way of doing this is to attach to the back of a diaphragm a light
rod or tube into which all the separate microphones which may be some hundreds
in number, articulate, the rod or tube itself may form an electrode. The other
ends of the microphone are articulated into suitable supports, which may be
tubular.
When very loud effects are desired or where speech has to be transmitted to a
very great distance I find it useful to assist the action which goes on at the points
of contact by vibration or by heat When mechanical vibration is applied it may
be obtained by clockwork or by the varying movements of a friction brake upon
a rotating wheel or other moving surface the said friction brake being itself con-
trolled by the vibrations of the voice and in turn controlling the amount of
mechanical movement imparted to the microphones.
When heat is applied it is convenient to pass heated air from a burner or flame
or other suitable source of heat through the tubes which have been mentioned as
serving as electrodes or as supports for the contact pieces of the microphones; and
where tubes are employed they may be perforated to permit the heat to have access
to the contacts of the microphones or the heat may be conducted thereto by metal
rods or pieces.

page_text: I SILVANUS PHILLIPS THOMPSON of 20 Arundel Gardens Notting Hill in the
County of Middlesex Doctor of Science and Professor of Experimental Physics
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
My improved instruments are designed chiefly for increasing the power of
telephonic transmission and embody several new features of construction and a
new method of working-According to my Invention a very large number of small
and light microphones are arranged in parallel arc and they are capable of being
tested and adjusted either singly or in groups-They are supplied with current
either singly or in groups from a battery or batteries and where fewer batteries
are employed than microphones, resistances may be introduced to equalize their
action These microphones are so arranged that the vibrations of the voice are
simultaneously imparted to the whole of them or to the contact points of the
whole of them either directly or by means of a suitable diaphragm or diaphragms
or by a suitable tube or tubes or both together and a convenient way of doing this
is to attach to the back of a diaphragm a light rod or tube into which all the
separate microphones (which may be some hundreds in number) are articulated or
mounted the rod or tube itself may form an electrode. The other ends of the
microphone are articulated into or mounted in suitable supports which may be
tubular.
5
Figure 1 of the accompanying drawing represents in section and Figure 2 in
sectional plan on the line y. Figure 1 a transmitting instrument provided with
multiple microphones according to my Invention. A is the mouth piece and B the
diaphragm which may be mounted in or on a suitable case or carrier in the usual
or any convenient way. To the centre of the diaphragm B is connected one end
of a metal or other rod or tube C to which are fixed conducting pieces D preferably
of good conducting carbon, such as hard retort carbon having therein recesses d in
each of which is held one end of the microphonic rods or pieces E (also preferably
of like carbon) the other ends thereof being similarly mounted in suitable con-
ducting pieces F. preferably of like carbon notched at f and supported by any
suitable frame or support. The current is led in by branch wires
the pieces F and out of the wire h attached to the rod or tube C. Figure 3 shows
a similar arrangement to that shewn in Figures 1 and 2 but having the side
pieces F also fixed to rods or tubes 0 attached at one end to the diaphragm B.
attached to
In this arrangement the current is shown as coming in and leaving by the
pieces F on the side rods respectively, but it may come in by the side rods and
leave by the central rod or vice versa in any similar suitable manner, but so that
a large number of microphones are arranged in parallel arc with one another in the
circuit.
Figure 4 shows a central rod or tube C. of carbon in which the inner ends of the
microphonic rods are directly inserted the current being led in by the wires g and

page_text: leaving by the wires the diaphragm B being secured to the diaphragm B by a
screw as shewn.
Figure 5 shews an arrangement with the microphonic rods or tubes mounted in
the central rod or tube C and in segmental pieces F so that they radiate as shown.
There will be any suitable number of repetitions of these set one beneath the other
in layers or sets along the rod or tube C. Figure 6 illustrates in transverse section
and partial elevation a modification wherein there are separate vertical rods or
tubes F for each vertical line of microphonic rods or tubes in place of the curved
pieces shewn in Figure 5.
Figure 7 shews in longitudinal section and perspective an arrangement wherein
the microphonic tubes or rods E rake or slope and are supported in carbon
pieces D and F, those at D being fixed to a rod secured to the diaphragm B and
those at F being mounted on any suitable support.
Figure 8 shows an arrangement wherein the microphonic arrangement is like
that at Figures 1 and 2 and is marked with the same letters of reference but the
rod C is attached to a slip C³ of metal, wood, leather, or any other suitable material
to act as a friction brake bearing against a drum J slowly rotated as indicated by
the arrow by clockwork or any suitable means and of metal wood or any suitable
hard material. The diaphragm B is fixed by an adjusting screw b to a piece k
between which and the piece c on the brake is a presser L of rubber. The action
of this is hereinafter described.
The bottom end of the rod O should be fixed in some semi-rigid support, such as
a leather collar or strip as shewn clearly in section in Figure 9 where the collar or
strip is marked m.
Figure 10 shows the microphonic arrangement as in Figure 1, but with an electro
magnet N either in shunt or in series with the set of microphones above the soft
iron armature 63 at the centre of the diaphragm B. Figure 11 shews the electro
magnet N beneath a leather strip m like that at Figure 9 the lower end of the
rod C of the microphonic arrangement being furnished with the soft iron armature b*.
The actions of these are hereinafter described.
In all the arrangements the current or currents may be led in and out in any
suitable way (for example as hereinbefore shewn) so that it or they passes or pass
through all the microphonic contacts.
It will be understood that although in the drawing I have not shewn all the
microphonic rods or tubes that may be used throughout the length of the supports
that they are repeated throughout all the supports and are employed in superposed
sets or layers.
In operating large numbers of microphones at once or where very loud effects
are required or a great distance traversed I find it convenient to assist the
operation of the instrument by aiding by mechanical vibration or by heat the
action which goes on at the points of contact of the microphones when they are
vibrated by the voice-Such aids form a separate part of my Invention and I now
proceed to describe some of the ways which I consider best for carrying out this
part of my Invention for assisting the voice, vibrations by extraneous mechanical
or thermal motions.
To impart mechanical motion to the microphones or to the rod or tube to which
they are adjoined or to the diaphragm (if any) which is combined with the
microphones I may employ a mechanism such as is shewn in the herein before
described Figure 8 which depicts a sort of friction drum wheel roller or disk with
a friction brake driven mechanically but controlled by the vibrations of the voice
which act by means of a suitable diaphragm upon the friction brake The roller or
wheel rubs in rotating against the brake and tends to draw up the central rod-
This is held semi-rigidly at bottom by a stiff spring or leather collar or strip
or other like support and hence it slips back continually and is continually
catching and slipping on the friction drum or wheel. The voice vibrations vary.

page_text: the pressure of the brake on the drum and the movements of catching and slipping
therefore correspond to the voice vibrations but are of greater amplitude.
It is obvious that the friction roller may be rotated either by hand or by
clockwork driven by spring or by weight or by an electric motor. The driving
machinery of whatever species should move smoothly and noiselessly so as not to
impart needless jarring of any description to the microphones and it is expedient
where any risk of such jarring is likely to arise to mount the roller or wheel upon
a hub of soft rubber cork or other elastic body to deaden any such transmitted
extraneous vibrations.
This arrangement of friction brake and adjuncts may be employed with any
suitable description of transmitter or microphone such for example as that above
described or with a microphone consisting of granulated or powdered coke or
the like.
Another way of obtaining the requisite mechanical vibration to assist the
vibrations of the voice is by an electromagnet and its armature (as described
herein before with regard to Figures 10 and 11) suitably mounted upon a spring
or yielding support so as to afford the requisite moving surface the electro magnet
being in turn controlled by the microphones or by one or more of them so that
when the currents circulating in its coils are varied by the action of the micro-
phones the electromagnet imparts mechanical movements to the armature which
assist the vibrations and amplify them.
When heat is applied it is convenient to pass heated air from a burner or flame
or other suitable source of heat through the tube or tubes which have been
described as serving as electrodes or as supports for the contact pieces of the
microphones and where tubes are employed they may be perforated to permit
the heat to have access to the contacts of the microphones or the heat may be
conducted thereto by metal rods or pieces, copper being a suitable metal being the
best cheap conductor but it should be faced with platinum or with inlaid pieces of
good conducting carbon at the contacts being itself liable to oxidation when heated
in presence of air.
Figure 12 illustrates such an arrangement-The microphonic arrangements are
shewn as being like those hereinbefore described the corresponding parts being
marked with like letters of reference but the outer support F' (or all of them if
more than one be used) is a hollow carbon tube with a funnel at f* beneath which
is a small gas flame f³ the heat of which passes by the funnel into and along the
tube F and escapes by the copper tube F serving as a chimney.
Having now particularly described and ascertained the nature of my said
invention and the manner in which the same is to be performed I declare that what
I claim is
First. In telephonic transmitters the microphonic arrangement consisting of
multiple or superposed contacts arranged in superposed sets or layers substan-
tially as and for the purpose hereinbefore described and illustrated by the several
examples shewn in the Drawings.
Second. In telephonic transmitters the arrangement of microphones in sets or
layers acted upon by a central rod, tube or support which imparts the vibrations
of the sound to them simultaneously at each of its movements substantially as
hereinbefore described and illustrated.
Third. In a telephonic transmitter the hereinbefore described method of ampli-
fying the voice-vibrations by superadding mechanical or thermal motions to them
to assist them the said mechanical motions however derived being themselves
controlled by the voice vibrations which they assist substantially as hereinbefore
described and illustrated by figures 8. 9. and 12 of the accompanying drawings.
Fourth. The combination of a friction brake and roller with a telephone trans-
mitter or microphone substantially as and for the purpose hereinbefore described
and illustrated by Figure 8.,

page_text: Fifth. The combination of an electromagnet and armature with a microphone to
add mechanical movement to the microphone the said electro magnet being itself
controlled by the voice-vibrations as hereinbefore described and illustrated by
Figures 10 and 11 of the accompanying Drawings.
Sixth. The arrangement of artificially heated microphonic transmitter illustrated
in figure 12 of the accompanying drawings.
Seventh. The several arrangements and combinations of parts hereinbefore
described and illustrated and constituting or partly constituting microphonic
transmitters.