IMPROVEMENTS IN TELEPHONIC APPARATUS
Year: 1885

page_text: JOHN MUNRO, Electrician, 2 Somerset Villas West Croydon Surrey do hereby
declare the nature of my invention for IMPROVEMENTS IN TELEPHONIC APPARATUS
to be as follows....
The main object of these improvements is to provide a self-adjusting metal
microphone transmitter and overcome the irregularity of working which is a
drawback to the use of metal contacts in telephone transmitters. This is done by
the use of several balls, or other rolling bodies, free to roll on the electrodes
between which they convey the current. The electrodes may take the form of
rails, or wires, with the balls, cylinders, or other rolling bodies, supported by and
between them, or of plates above and below the rollers. If only one plate or
electrode above or below is used, the balls or rollers should be connected together
so as to roll in company. The edges of the rails can with advantage be made
sharp and the contact surfaces of the rollers and electrodes are preferably
roughened, which may be done in divers ways. Wire guaze can be used for the
contacts.
The microphonic or telephonic contacts thus formed may be enclosed in an
air-tight box, or immersed in a preservative liquid. Glycerine or other sluggish
liquids are sometimes employed by me to damp the vibrations. The box
may be
supported from a bracket, or by a stand, or by lines more or less elastic. I may
also immerse the contacts under the surface of a mass of liquid; or I may leave
the metals open to the air and cause the sound waves to act direct upon them bý
means of a tube, bringing these over the moving pieces. I may also focus the
sound on the microphone by a sound lens: or screen it from the voice and breath
by an intervening screen, say of wire gauze, cloth, skin, or paper.
J
Single microphones consisting of the rollers and electrodes can be combined
together in "series" or in "quantity," and with one or more sources of electricity,
and induction coils, according to practice. Iron is a good material: but they may
be made of other metals and alloys.
With iron or other magnetic metals in the balls I may use the microphone as
a telephone relay by placing the pole of an electromagnet, in circuit with the line,
between the electrodes or so as to attract the balls or rollers which rest upon and
between or across them. The microphone being in circuit with a local battery and
telephone, or line, may be actuated by the current in the electromagnet. I may
also add a moveable magnet to the microphone for inductive and regulating
purposes..

page_text: Improvements in Telephonic Apparatus.
JOHN MUNRO of 2 Somerset Villas West Croydon, Surrey, Electrician, 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:-
The apparatus consists of an arrangement of contacts or current regulator of
a design such that it can be actuated by the sound waves direct without the
intervention of a tympan, and can also be made of metal. Two or more balls from
the size of a shot, say, and upwards according to the metal used or other circum-
stances, rest upon and between two parallel edged rails, or other sharp-edged
supports of metal, and are free to roll on the same, and take up new positions.
By giving them this freedom the balls do not get into a seat or fixed position;
fresh surfaces come into contact; and the instrument is in a measure self-adjusting.
Instead of balls, cylinders or other rolling bodies may be used; and wires may take
the place of the rails, as supports. The electric current passes from one rail to the
other through the balls or "rollers" as we may call them, and the sound waves
passing down through the open arrangement agitates the balls and regulates the
strength of current passing. To direct the sound waves evenly through the regu-
lator various well known devices are used, such as reflectors, speaking tubes, etc;
care being taken that the air-waves act directly on the regulator. Sometimes the
regulator is swung by strings in a small box.
A number of these single regulators can be grouped together "in series " in the
circuit, so that the sound-waves pass through them and affect them simultaneously.
This arrangement is to give louder effects; each regulator in the group influencing
the current in conjunction with the others. An advantage of having two or more
balls on the same pair of rails is that there is less danger of interrupting the
current by over loud speaking; as no device is used to keep a closed circuit. The
contacts are so designed that for ordinary loudness of speech they will not open.
In this respect the apparatus is a modification of the metal contacts of the well
known Reis transmitter.
By placing the pole of an electromagnet between the rails so as to act on the
balls or rollers when these are of a magnetic metal, a relay current regulator is
produced. For when a current passes through the coil of the electromagnet it
influences the balls by induction, and thus regulates the current passing through
them from rail to rail.
To prevent "extra"-sparking should the balls interrupt the current, a condenser
may be connected between the rails; or resistances may be connected in the same
position, the balls in their action serving to shunt these resistances.
More than one metal may be used to form the same regulator With thermo-
electric metals heat may be so applied as to warm the contacts of the rollers with
one rail, leaving the contacts with the other cool, thus generating a thermo-electric
current. The regulator may also be combined with other sources of current,
magneto-electric, voltaic, or other. Heat may also be used to prevent damp and
facilitate working. I do not rely upon carbon as a material in the making of the

page_text: regulator; although it may be permissible to do so since the sound-waves act
directly; iron is a material which I have found successful; but other metals may
be used.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:
(1.) I claim the current regulator consisting of a number of balls or rollers resting
on rails substantially as described.
(2.) I claim the use of this regulator, in a telephone, with reflectors, tubes, and
such devices to direct the sound-waves on it.
(3.) I claim the relay-regulator substantially as described.
(4.) I claim the combination of the regulator with induction coils, condensers,
resistances, and sources of electricity substantially as described.