IMPROVE- MENTS IN APPARATUS FOR THE TRANSMISSION OF VOCAL AND OTHER SOUNDS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Frederick John Smith at the Office
of the Commissioners of Patents on the 31st October 1881.
FREDERICK JOHN SMITH, of Taunton, in the County of Somerset. " IMPROVE-
MENTS IN APPARATUS FOR THE TRANSMISSION OF VOCAL AND OTHER SOUNDS."
This Invention has for object improvements in apparatus for the transmission
of vocal and other sounds.
According to my Invention, I make transmitters in special forms according to
the nature of the sound or sounds that they are designed to transmit as described
below. In one form of transmitter adapted for the transmission of vocal and
musical sounds, a cubical or rectangular box of wood or of other suitable material
has holes cut in each of its sides, and has pine wood sounding boards attached to
two or more of such sides for carrying the carbon conductors. By this arrange-
ment sounds coming to the rectangular box in any direction will strike some
sound board at an advantageous angle, and so cause the vibration of the carbon
conductor which may be connected in parallel arc or in series, or partly parallel
and partly in series. Or one side of the cubical or rectangular box may be open,
sound being directed into the interior of the cube through the aperture. In a
transmitter according to this part of my Invention I prefer to arrange the cube as
follows: The bottom is connected to the support or stand, No. 1 side is open for
the reception of the sound; sides Nos. 2, 3, and 4, cach carry a carbon microphone,
while a fourth microphone is placed on the top. The connections are so designed
as to provide two parallel circuits for the current, each circuit comprising two
microphones in series.
In a modified form of transmitter for vocal and musical sounds, the cubical or
rectangular box has no open side, the sound being conveyed into its interior by a
flexible pipe attached to its lower or one of its other sides, and terminating in a
mouth piece. A carbon microphone is attached to or carried by each side, and
two such microphones are also placed on the top. These microphones I connect
together in any suitable manner to produce several parallel circuits.
In a transmitter for talking and general uses, according to my Invention I
employ rods or cylinders of carbon that have not been reduced or shouldered down
as is usual, and these are carried in a frame having cells, each cell being designed
Dino A77

page_text: to receive one carbon cylinder. In practice I employ more or fewer carbon cylin
ders according to the object I have in view, the greater the number the better
being the timbre or quality of the sound or voice transmitted, and the fewer the
number the greater the volume or intensity of the sound. Each carbon cylinder
rests at its ends upon rods or strips of carbon running crosswise of the cells, the
contact being either that of two circles touching externally, or that of a circle and
a straight line.
In one form of transmitter for talking and general purposes according to my
Invention a rectangular frame is divided by six longitudinal and two cross bars
or partitions into twenty one cells. Immediately below the partitions are four
cross bars of carbon which support the rods or cylinders that lie in the cells, the
said cross bars being carried by the frame to which the sound board is attached.
The connections are so arranged that the current can enter at the first carbon
cross bar and leave at the fourth, thus traversing the carbon cylinders in several
parallel lines, cach consisting of three carbon cylinders placed in series; or the
current may enter at the first and third bars, and leave at the second and
fourth.
In transmitting music, etcetera, several rectangular transmitters may be
electrically connected together and situated in different parts of the room, theatre,
or other place, each being provided with a separate induction coil, or all may be
connected with one induction coil, with a primary wire to each transmitter.
When using the apparatus for speaking purposes, the sounding board which
forms the underside of the transmitter, as hereinabove described, is spoken to and
is placed at a suitable height for the purpose.
The cutting out of the bell, the connection of the secondary-wire-of-the-
induction coil to the line,-the-connection of the primary wire of the induction coil
to the battery, etcetera, are effected in apparatus for the transmission of vocal and
other sounds according to my Invention by means of a hooked lever so arranged
that when the telephone or a weight taken off one end, the lever falls, carrying
with it a slide provided with two contact pieces moving in front of three fixed
contact pieces, one of the moving contact pieces being in connection with the
battery for working the microphone, and the other in connection with the line
wire. Movement of the slide in one direction cuts out the battery and connects
the bell to line, and movement in the contrary direction couples the battery to
the transmitter, and the secondary wire of the induction coil to line, cutting out
the bell.
In a telephone according to my Invention the vibrating diaphragm has under
it, instead of one or two coils as usual, several coils, by preference six, placed in a
circle, the cores and bobbins being segmental in shape. Flat coils may be also
used placed side by side under a round or an oblong vibrating plate or diaphragm.
The soft iron cores of each telephone are magnetized by induction as in other
systems by a horse shoe magnet, each opposite coil of the six, when six are used,
being respectively on the N and S of a U shaped magnet.
The U shaped magnets are of gradually diminishing lengths, in order that their
poles may be arranged in a circle without their rounded ends coming into contact
with each other. In the case of flat coils the magnets are flat, the two outer coils
forming the poles of one magnet, the next couple within forming the next poles,
The coils may be so connected together that the current may be either
sent through the whole of them successively by a single line wire, or it may be
sent from three line wires, a cable of three strands of insulated wire into three
pairs of bobbins simultaneously, each line wire being by preference attached to
a separate transmitter.
and so on.
The flexible electric connections to the telephone or telephones are fixed to the
wall or any firm mass near to the transmitter, so that the vibrations of the
hand of the person holding the telephone are not imparted to the transmitter.
To exclude outer sounds, and to prevent the telephone from touching the ear, I
employ an annular elastic ear pad, which I attach or slip on to the mouth of the

page_text: telephone. This ear pad I make by preference of india rubber, and I so construct
it as to be applicable to existing telephones.
For the bell push I employ a small weighted lever pivotted on axis connected
to the line wire, and which in moving rubs against two small springs, the upper of
which is connected to the positive pole of the battery, and the lower to the bell,
and through it to the negative pole; the weight keeps the line wire in circuit with
the bell, except when the push is depressed to call the distant station.
When a relay is required, as in long circuits, I employ an instrument generally
resembling a single needle telegraph placed in the horizontal position. In such an
instrument a galvanometer needle suspended by a thread moves in a flat coil, and
is connected to a vertical spindle passing through the coil. This vertical spindle
carries a finger, which as it is moved up to a stop by the galvanometer needle
under the line current completes the circuit of a local battery through a bell.
The local current is conducted to the vertical spindle by means of a coil or
helix of fine wire, and passes down the spindle through the abovementioned finger
to the stop. If desired two bells may be used, each connected to one of the stops,
or only one bell may be used connected to one stop, the other stop being
insulated.
In some cases I construct terminals, each of a metallic washer stamped out with
a radially projecting tail.
This tale I bend down at right angles and pass through the base board of the
apparatus, attaching it to the instrument wire at the other side.
A screw with a flat head makes good the contact between any wires connected
with the instrument and the washer.