IMPROVEMENTS IN AND APPER- TAINING TO MICROPHONIC APPARATUS
Year: 1879

page_text: LETTERS PATENT to Williamı Phillips Thompson, of the Firm of W. P.
Thompson and Co., Patent Agents and Consulting Engineers, of 6, Lord
Street, Liverpool, in the County of Lancaster, and 323, High Holborn, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN AND APPER-
TAINING TO MICROPHONIC APPARATUS." A communication from abroad for
Monsieur Leon De Locht, of Liége, in the Kingdom of Belgium, Civil
Engineer.
Sealed the 16th December 1879, and dated the 29th August 1879.
PROVISIONAL SPECIFICATION left by the said William Phillips Thompson,
at the Office of the Commissioners of Patents on the 29th August 1879.
WILLIAM PHILLIPS THOMPSON, of the Firm of W. P. Thompson and Co., Patent
Agents and Consulting Engineers, of 6, Lord Street, Liverpool, in the County of
Lancaster, and 323, High Holborn, in the County of Middlesex. "IMPROVEMENTS
IN AND APPERTAINING TO MICROPHONIC APPARATUS." A communication from.
abroad from Monsieur Leon De Locht, of Liége, in the Kingdom of Belgium, Civil
Engineer.
The following is a literal translation of the Specification sent me from Belgium
with orders to file.
"
The apparatus consists in a very thin but rigid wooden, metal, or other
planchette "board or plate, of which the form and dimensions, so long as they are
sufficiently spread out, can be otherwise varied. Its form is usually that of a
rectangle of six centimetres of base upon five of height. Its thickness is two
millimetres. This planchette is movable round one of its edges as an axis, and for
this purpose at the two extremities of this edge are arranged two small metal
straps in which the points of two metallic screws engage fixed by their supports
upon the main board.
At the part opposed to the axis of suspension is attached a prism of dogwood
charcoal, of graphite, of graphitic carbon, or of any other mediocre conductor of
electricity. Upon the anterior face of this prism are held by means of metallic
flexible springs fixed upon the main board one, two, or more little fragments of
graphite, of graphitic carbon, or of any other similar matter. These metallic springs
can be straight or spiral, their tension is regulated by the aid of a screw.
springs are preferably sheet brass soldered to their supports by one of their
ID 631
These

page_text: extremities, being traversed about a centimetre from that extremity by a screw,
which turning in a tapped nut in the support determines the movement of the
spring in one direction or another.
The movements of the planchette, limited in one direction by the springs and
their extremities in graphite, are limited in the other direction by the pressure of
an antagonistic spring, which can be regulated at will. A long flat spring is some-
times used for the purpose fastened by one of its extremities to the main board, the
other free extremity pressing itself upon the planchette while a screw turning in a
nut soldered at a centimetre from the extremity of the spring regulates the
movements of said spring.
The planchette is habitually arranged in a vertical position of unstable
equilibrium.
Instead of being moveable about one of its edges the planchette can be fixed to
the extremity of a vertical rigid trunk which has for its function the elongating
of the arm of the lever of the movable apparatus. In another disposition the
planchette is parted at its lower part by a metallic point plunged into a metal
sheath, it carries at its upper part two fragments of graphite or other like material
of little conductivity movable in supports of the same material, the position
of which can be regulated by springs in the same way as the position of the
planchette.
One increases the sensitiveness of the apparatus for the transmission of feeble
sounds by placing an ear trumpet before the planchette.
The "microphone planchette" is introduced in the circuit of a voltaic battery
containing the telephone receptors (receiving telephones) or in the primary circuit
of an induction coil attached to the voltaic battery; the secondary circuit of the
coil containing the telephones.
The current can traverse the microphone in going by the metallic conductor to
the prism of graphite onward to the springs and to other conductors, or by the
springs exclusively, the prism of graphite forming the conducting connection
between them in such manner that the current entering by the metallic conductor
and the left spring traverses the prism of graphite and goes out by the right spring
of the metallic conductor. The multiplying microphone-planchette disposes upon
the same voltaic circuit (or upon many circuits tied to one or many telephonic
lines) several microphonic-planchettes placed side by side in one or many ranges,
they can be adapted upon a single main board of sufficient dimensions. These
planchettes receive synchronously the impulsions of sound transmitting them
synchronously in such manner as to propagate them in many directions simul-
taneously, or to increase them and render them more distinct in a single receiving
apparatus.
In conclusion the object of the Invention is to augment the sensibility and the
regularity of speaking microphones.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Phillips Thompson in the Great Seal Patent Office on the
28th February 1880.
WILLIAM PHILLIPS THOMPSON, of the Firm of W. P. Thompson and Co., Patent
Agents and Consulting Engineers, of 6, Lord Street, Liverpool, in the County of
Lancaster, and 323, High Holborn, in the County of Middlesex.
IMPROVEMENTS,
"
IN AND APPERTAINING TO MICROPHONIC APPARATUS." A communication from
abroad from Monsieur Leon De Locht, of Liége, in the Kingdom of Belgium, Civil
Engineer.
In the following I have endeavoured to give a literal translation of the
Specification sent me from Belgium with orders to file, only altering it occasionally
to suit English law and practice where absolutely necessary.
"
The apparatus consists in a very thin but rigid wooden, metal, or other
planchette" board or plate of which the form and dimensions, so long as they are
sufficiently spread out, can be otherwise varied. In the Drawings annexed Fig. 1
is a front elevation, and Fig. 2, a longitudinal section; the planchette is shown at
A, A. Its form is usually that of a rectangle of six centimetres of base upon five of
height; its thickness is two millimetres. This planchette is movable round one
of its edges as an axis, and for this purpose, at the two extremities of this edge, are
arranged two small metal caps a, a, in which the points of two metallic screws b, b,
engage, fixed by their supports upon the main board B, B. At the part opposed
to the axis of suspension is attached a prism C, C, of dogwood charcoal, of graphite,
of graphitic carbon, or of any other mediocre conductor of electricity. Upon the
anterior face of this prism are held by means of metallic flexible springs r,, fixed
upon the main board B, B, one, two, or more little fragments d, d, of graphite of
graphitic carbon or of any other similar matter. These metallic springs can be
straight or spiral, their tension is regulated by the aid of a screw. Upon the
Drawings the two springs r, r, are flut springs of sheet brass soldered or brazed to
their supports by one of their extremities, being traversed about a centimetre from
that extremity by screws V, V, which, turning in tapped nuts in the support,
determine the movement of the spring in one direction or another.
The movements of the planchette, limited in one direction by the springs r, r,
and their extremities in graphite, are limited in the other direction by the pressure
of an antagonistic spring, which can be regulated at will. Figs. 1 and 2, show at
E, E, a long flat spring fastened by one of its extremities to the main board B, B,
the other free extremity pressing itself upon the planchette A, A, while a screw
H, turning in a nut solldered at a centimetre from the extremity of the spring
regulates the movements of said spring.
The planchette A, A, is habitually arranged in a vertical position of unstable
equilibrium. Instead of being movable about one of its edges the planchette A, A,
can be fixed to the extremity of a vertical rigid trunk t, t, Fig. 3, which has for its
function the elongating of the arm of the lever of the movable apparatus; the stem
t, is soldered at its lower end to the movable axis u, a. In another disposition the
planchette is parted at its lower part by a metallic point plunged into a metal
sheath. It carries at its upper part two fragments of graphite or other like
material of little conductivity, movable in supports of the same material, the
position of which can be regulated by springs in the same way as the position of
the planchette. One increases the sensitiveness of the apparatus for the trans-
mission of feeble sounds by placing an ear trumpet before the planchette. This
instrument known as the "De Locht Pantéléphone" is introduced into the circuit
of a voltaic battery containing the receiving telephones, or into the primary circuit
of an induction coil attached to the voltaic battery; the secondary circuit of the
coil containing the telephones.

page_text: "
The current can traverse the microphone in going by the metallic conductor P.P,
to the prism of graphite C, C, onward to the springs 7, 7, and to other conductors
q, q, or by the springs r, r, exclusively, the prism of graphite forming the con-
ducting connection between them in such manner that the current entering by the
metallic conductor q, and the left spring traverses the prism of graphite and goes out
by the right spring and the metallic conductor q. The "De Locht Pantelephone
disposes upon the same voltaic circuit (or upon many circuits tied to one or many
telephonic lines) several microphonic planchettes A, A, placed side by side in one
or many ranges. They can be adapted upon a single main board B, B, of sufficient
dimensions. These planchettes receive synchronously the impulsions of sound
transmitting them synchronously in such manner as to propagate them in many
directions simultaneously, or to increase them and render them more distinct in
single receiving apparatus.
Figs. 4 to 7 show an improved or simplified form of the apparatus as shown in
Fig. 1.
The improvement consists in the new mode of fixing the movable planchette or
slab. Instead of making it act by simply pressing a spring E, E, (see Figs. 1
and 2) upon the posterior face of the planchette, oscillating upon its lower edge
of which the ends hollowed out of the cap receive the points of two metallic screws,
this movable slab is tixed directly with two flat very supple springs, and these
again are attached by their lower extremities to the support of the apparatus.
The apparatus instead of being suspended in a vertical position of unstable
equilibrium (the axis of suspension being situated below the centre of gravity of
the movable slab) can also be suspended in the inversed position.
One of the carbons establishing the contact of variable conductibility can be
replaced by platinum, copper, silver, or any other metal. One can equally
substitute for the other carbon a metallic body, and preferably spongy platinum.
The two pieces in contact have the same surface of revolution, but the one concave,
the other convex. This disposition increases the surface of contact and
improves the conductivity of the apparatus.
The pantelephone is represented in the annexed Drawings. Figs. 4 and 5 represent
the first type of the simplified form, front view and section; Figs. 6 and 7 show
the second type in the same manner.
DESCRIPTION OF THE FIRST TYPE —(Figs. 4 and 5).
The slab A, A, A, A, is formed of any convenient material, sheet iron, steel, or
brass, mica, wood; vulcanite, cork, aluminium, et cetera, et cetera. In the Drawing|
it is constituted of a frame of deal twelve millimetres thick in its section which is
rectangular. Upon the anterior face of the rectangle is glued a sheet of parchment
or paper P, P, lightly stretched. The rectangle is thirty two centimetres long and
fifty centimetres high.
Two little flat steel or brass springs R, R, are fixed by the axis of their
extremities upon the lower sides of the long sides of the rectangle, and penetrating
into a notch made half through the wood. The other extremity is fixed upon the
support S; S, of the apparatus. The length of the part of the springs which can
spring is in this instance five centimetres; this dimension can vary according to the
size of the apparatus.
The slab is inovable, but solely in one direction, in such fashion that the imaginary
axis a, a, of the apparatus is maintained always in a plane normal to that of the
support and to that of its suspension. Upon the middle of the upper side of the
movable rectangle or slab is fixed a fragment of graphite g hollowed to a surface of
revolution which weighs in its normal position also as feebly as possible against
the rounded convex surface of the "butoir" a second fragment of graphite h fixed
to the extremity of a little brass spring C; this last is brazed by its other extremity
to a support d, and a screw turning in a hole tapped in the support at a centimetre
from the brazing permits one to augment or diminish the tension of the spring.

page_text: The support d of the spring is fixed immovably upon the frame B, B, B, B, which
forms the main structure of all the apparatus. In place of the spring carrying the
"butoir" in carbon or inetal one can also employ a fixed "butoir."
The pantelephone can be attached to the wall by the eyelets 0, 0, 0, 0, two screws
V, V, turning in nuts in the upper part of the frame B, B, B, B, permitting said
frame to hang more or less apart from the wall, and to obtain the feeble contact of
the movable carbon g with the fixed carbon h. The carbon g has metallic con-
nection by copper wires which follow the long sides of the rectangle with the two
springs R, R; these are themselves attached metallically to the terminal L. The
spring C and its support d are on their part attached to the terminal T. The
electric current entering by L, for example, follows in the apparatus the route
L, R, g, h, C, d, T. To prevent too great amplitude of movement of the slab a
key M limits the back travel; the forward travel is limited by the spring C.
DESCRIPTION OF THE SECOND TYPE-(Figs. 6 and 7).
The apparatus of the second type is formed simply of a rigid planchette or slab
A, A, in thin sheet brass, with sides ten centimetres long carried by two blades of
the same metal solidly attached to the slab. These blades are two centimetres
by eighteen centimetres; they form springs at their lower parts for a length of five
centimetres. The screw V and the key M have the same functions here as in the
first type. The spring C carrying the carbon h is formed of a simple strip of thin
metal fixed upon a wooden support d.
The springs R, R, instead of being fixed by screws at their lower extremity upon
the supports S, S, can be screwed into two parallel jaws movable in the length of
the springs in such manner as to be able to lengthen or shorten their springing
parts as required. The movable planchette or slab can be shaped variously; its
superficial dimensions, weight, and material can also vary within wide limits; it
can be of wood, cardboard, gutta percha, mica, ivory, metal, et cetera. Noise
dampers (sourdines) of gutta purcha, india rubber, wadding, cotton, et cetera, can be
applied to the different inovable pieces as well as to the support of the apparatus.
The springs can be varied in their dimensions. One can by the aid of the eyelets
0, 0, 0, 0, suspend the apparatus from either end.
The inventor has endeavoured in this last design to simplify the construction of
the pantelephone by the suppression of movable hoods on the points of the screw,
and to assure its good working by the elimination of all cause of derangement, to
obtain by the flat springs a direction of movement perfectly normal to the axis of
suspension, to permit easy regulating of the apparatus, and in fine to construct
apparatus of all forms and of all sizes having each an appropriateness for the usages
to which it is destined.
The object of the entire Invention is, first, to augment the extent of sound
receptive surface, without augmenting the weight of the movable apparatus, in such
manner as to obtain by the increase of extent of surface struck by the layer of air
put in movement by the action of the voice a more intense effect; second, to augment
the mobility of the apparatus of which the position of unstable equilibrium is
regulated by two contrary forces of very feeble intensity; third, to augment the
tension of small antagonistic springs in such manner that all actions, however
feeble they may be, introduced into the system of forces, modify the position of
the apparatus; fourth, to augment the amplitude of the movements of the planchette
by the prolonging of the arm of the lever of its centre of pressure relatively to its
axis of suspension; fifth, in the microphone multiplier by the addition of like
effects obtained in each of the juxtaposed microphones to multiply the resulting
sound.
Having now described the Invention, I wish it to be understood that what 1
believe to be new and desire to protect under the herein before in part recited Letters
Patent is:-
First. The manufacture and use of the microphonic apparatus, substantially as
hereinbefore described and illustrated in the accompanying Drawings.

page_text: Second. The mode of multiplying the effect by connecting several microphonic
planchettes placed near together to the same voltaic circuit, substantially as
described.
In witness whereof, I, the said William Phillips Thompson, have hereunto set
my hand and seal, this Twenty seventh day of February, in the year
of our Lord One thousand eight hundred and eighty.
W*. P. THOMPSON. (L.S.)