Improvements in Telephonic Apparatus.
Year: 1892

page_text: Date of Application, 3rd June, 1892
Complete Specification Left, 28th Jan., 1893-Accepted, 11th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in Telephonic Apparatus.
I, AMBROSE MYALL, of 21 Cockspur Street, in the City of Westminster, Civil
Engineer, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by W. Stuart Harrison, of Hongkong, Electrician)
to be as follows:-
•
The said invention relates primarily to the application of a single fluid cell to
provide the current for the microphone circuit in telephonic apparatus, and
secondarily to the elimination of a switch, subsequent upon this application.
A battery or cell is employed in which the zinc or other electro-positive element
is inserted in, or withdrawn from the exciting solution through a lever, or system
of levers, actuated by taking the receiver off the hook or replacing it, or by any
other method whereby the electro-positive element is inserted in the exciting
solution only during the period in which a current is required through the
microphone.
The connecting wires are so arranged that the withdrawal of the electro-positive
element from the solution takes the place of a switch in arresting the said current
through the microphone.
66
The form of battery, which is found to answer well for the purposes of the
invention, consists of a jar of glass, or other suitable material, half filled with a
solution of bichromate of potash and sulphuric acid, in which a carbon plate,
about 1 inches wide and an inch thick, preferably composed of what is known
as retort" carbon, is suspended permanently. This plate carries at its top a
lead cap in which is cast a brass terminal. From this a wire is led direct to the
primary coil of an induction coil, thence to the microphone and back to the zinc
element. The latter consists of an amalgamated round zinc rod of an inch in
diameter, inserted in the solution, when the battery is put in action, to a depth
of 14 inches and distant from the carbon plate about 1 inches, the latter being
permanently immersed to a depth of 2 inches. A battery so prepared has an
internal resistance of about 6 ohms and an electro-motive force of approximately
2 volts, and is upon the whole eminently adapted to the required purpose, a single
cell being all sufficient with any of the various types of microphones at present in
general use.
It is not intended to limit the battery to the use of a bichromate of potash and
sulphuric acid, or a chromic acid solution, and the carbon may either remain
permanently in the solution, or may be withdrawn simultaneously with the zinc,
and any form of battery may be used in which either one or both the elements can
be withdrawn in any suitable manner, when the current is not required.
The main advantages of the invention are as follows:-
It is less expensive to set up a cell of the kind above described, than a Leclanché,
as commonly used for telephonic purposes, this is especially the case where its high
electro-motive force and low internal resistance permit it to replace two Leclanché
cells, which are frequently required with the "pencil" forms of microphones.
For the production of the intermittent currents required in telephony, it is much
more durable than the Leclanche. There is positively no local action taking place
when the cell is not in use, and three times the quantity of current is obtained from
a given quantity of zinc, when used in this manner than is the case with the
Leclanche cell, while the unusually low internal resistance, before-mentioned, allows
the microphone to act more directly upon the current strength. The process of
recharging is much simpler, and occupies less time than with the Leclanché, as it

page_text: consists simply of replacing the spent solution by new, and when necessary replacing
the zinc rod.
The switch dispensed with by this invention is the one which gives the most
trouble in practice, chiefly on account of the sparking which takes place every time
this circuit is opened.
The invention may readily, and at trifling expense be applied to the general types
of telephonic apparatus, as at present constructed and in use.
Dated this 3rd day of June 1892.
AMBROSE MYALL.
COMPLETE SPECIFICATION.
Improvements in Telephonic Apparatus.
I, AMBROSE MYALL, of 21 Cockspur Street, in the City of Westminster, Civil
Engineer, do hereby declare the nature of this invention (which has been com-
municated to me by W. Stuart Harrison, of Hongkong, China, Electrician) and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
This invention has primarily for its object, the application of a single fluid cell
to provide the current for the microphone circuit in telephonic apparatus, and
secondarily the elimination of a switch, subsequent upon such application.
In applying the invention, a battery or cell is employed, in which the zinc, or
other electro-positive element is inserted in, or withdrawn from the exciting
solution, through a lever or system of levers, actuated by taking the receiver off
the hook, or replacing it, or by any other method whereby the electro-positive
element is inserted in the exciting solution only during the period in which a current
is required through the microphone.
The connecting wires are so arranged that the withdrawal of the electro-positive
element from the solution takes the place of a switch, in arresting the said current
through the microphone.
The accompanying drawing, which forms a part of this Specification, represents
diagrammatically a complete telephonic apparatus, arranged in accordance with this
invention.
66
The form of battery which is found to answer well for the purposes of the
invention consists of a jar J of glass, or other suitable material, half filled with a
solution J¹ of bichromate of potash and sulphuric acid, in which a carbon plate K,
about 1 inches wide and inch thick, and preferably composed of what is known
as retort" carbon, is suspended permanently. This plate carries at its top a lead
cap K', which is cast on a brass terminal K². From this terminal a wire P¹ is led
direct to the primary coil of an induction coil E, and from thence the wire P² leads
through the microphone H to the lever D², from the end of which is suspended the
zinc element L.
The latter consists of an amalgamated zinc rod, of an inch in diameter,
inserted in the solution, when the battery is put in action, to a depth of 1 inches
and distant from the carbon plate about 14 inches, the latter being permanently
immersed to a depth of 2 inches. A battery so prepared has an internal resistance
of about 6 ohms, and an electro motive force of approximately 2 volts, and is
upon the whole eminently adapted to the required purpose, a single cell being all
sufficient with any of the various forms of microphones at present in use.
The microphone shewn at H is merely symbolic.
A is the receiver, hung on the forked end of the lever D', which is pivoted at D³
and connected to the lever D², pivoted at D', by the link d, so that the weight
of the receiver lifts the zinc L out of the solution, and this movement throws the
battery out of action and serves the purpose of a switch, to break the circuit
through the microphone.

page_text: When the receiver is taken off the book, the zinc drops into the solution, the
battery comes into action and the circuit through the microphone is closed.
F is the magneto alarm bell, the permanent magnet not being shewn, and G is the
magneto generator, the driving gear being omitted.
In the position of the parts shewn on the diagram with the receiver on the hook,
the battery is out of action, and consequently the microphone circuit inoperative,
while the magneto generator G and bell F are put to line through the switch B.
When the receiver is taken off the hook, contact is broken at B and the generator
and bell cut out, while the receiver and secondary coil S1 S2 of the induction
coil E are put to line through the switch C.
It is not intended to limit the battery to the use of a bichromate of potash and
sulphuric acid, or a chromic acid solution, and the carbon may either remain
permanently in the solution, as described, or may be withdrawn simultaneously
with the zinc, and any form of battery may be used in which either one or both of
the elements can be withdrawn in any suitable manner when the current is not
required. Again, I do not confine myself to the particular mechanical arrangement
shewn in the diagram for inserting or withdrawing the elements by the removal, or
replacement of the receiver.
The main advantages of the invention, are as follows;-It is less expensive to
set up a cell of the kind above described than a Leclanché as commonly used for
telephonic purposes, this being especially the case where its high electro-motive
force and low internal resistance, permit it to replace two Leclanché cells, which
are frequently required with the "pencil" forms of microphone.
For the production of the intermittent currents required in telephony this cell is
much more durable that the Leclanché.
use,
There is positively no local action taking place when the cell is not in and
three times the quantity of current is obtained from a given quantity of zinc, when
used in this manner, than is the case with the Leclanché cell, while the unusually
low internal resistance before mentioned, allows the microphone to act more directly
upon the current strength. The process of recharging is much simpler and occupies
less time than with the Leclanché, as it consists simply in replacing the spent
solution by new, and when necessary replacing the zinc rod.
The switch, which is dispensed with by means of this invention, is the one which
gives the most trouble in practice, chiefly on account of the sparking which takes
place every time the circuit is opened.
The invention may readily, and at trifling expense, be applied to the general
types of telephonic apparatus, as at present constructed and in use.
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 telephonic apparatus, a battery or cell in the microphone circuit of which
the electro-positive element is automatically withdrawn from the exciting solution
by placing the receiver upon its hook, thus throwing the cell out of action and
breaking the microphone circuit, while the said element is automatically inserted
in the solution by taking the receiver from the hook, thus putting the cell in action
and closing the said circuit, substantially as set forth.
2. In telephonic apparatus, a battery or cell in the microphone circuit, of which
both elements are automatically withdrawn from the solution or solutions, by
placing the receiver upon its hook, thus throwing the cell out of action and
breaking the microphone circuit, while the said elements are automatically inserted
in the solution or solutions by taking the receiver from the hook, thus putting the
cell in action and closing the said circuit, substantially as set forth.
3. In telephonic apparatus, an automatic switch in the microphone circuit,
consisting of a battery or cell in which one or both elements are automatically
withdrawn from or inserted in the solution or solutions, by placing the receiver on
the hook or removing it therefrom, substantially as set forth.

page_text: 4. In telephonic apparatus, a battery or cell J inserted in the circuit of the
microphone H, the zinc or electro-positive element L, suspended from a lever D³,
said lever being connected with a lever D¹ by a link d, so that when the receiver A
is hung on the lever D', the element L is withdrawn from the solution J¹, the cell
thrown out of action and the microphone circuit broken, and when the receiver is
taken off, the element L drops into the said solution and the said circuit is closed,
substantially as set forth.
5. In telephonic apparatus, a battery or cell J inserted in the circuit of the
microphone H, having a single fluid solution J', such as bichromate of potash and
sulphuric acid, or chromic acid, a carbon element K permanently inserted in said
solution, and a zinc element L automatically withdrawn from, or inserted in said
solution, by placing the receiver A on its hook or removing it therefrom,
substantially as set forth.
Dated this 28th dor of January 1893
AMBROSE MYALL.