A Method of and Apparatus for Telephonic Transmission.
Year: 1891

page_text: Date of Application, 21st Nov., 1891
Complete Specification Left, 21st Sept., 1892-Accepted, 1st Oct., 1892
PROVISIONAL SPECIFICATION.
A Method of and Apparatus for Telephonic Transmission.
I, ERHARD LUDWIG MAYER, of 11 Billiter Square, London, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention to be as
follows:-
In my invention I employ a mutual induction coil wound with two primary
windings and one secondary winding. The secondary winding I connect to earth
and line in the usual manner. One of the said primary windings I place in circuit
with a transmitter a battery and one winding of a double wound clectromagnet.
The other of the said primary windings I place in circuit with a battery and with
the other winding of the above mentioned double wound electromagnet.
When carrying my invention into effect I pass the currents from the two
batteries through the electromagnet and the mutual induction coil in one of two
manners: that is to say I (a) pass the two currents through the electromagnet in
the same direction and through the mutual induction coil in opposite directions, or
() pass the two currents through the electromagnet in opposite directions and
through and through the mutual induction coil in the same direction.
In some cases instead of employing an electromagnet as above mentioned I
employ a suitable resistance or self induction coil.
It is not necessary that the two batteries be entirely distinct.
E. L. MAYER,
Per J. G. Lorrain, M. Inst. E.E., M. lust. M.E.,
Norfolk House, Norfolk Street, London, W.C.,
Applicant's Patent Agent.
COMPLETE SPECIFICATION.
A Method of and Apparatus for Telephonic Transmission.
I, ERHARD LUDWIG MAYER, of 11 Billiter Square, London, in the County of
Middlesex, Engineer, 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 :-
In my invention I employ a mutual induction coil wound with two primary
windings and one secondary winding. The secondary winding I connect to earth
and line in the usual manner. One of the said primary windings I place in circuit
with a transmitter, a battery and one winding of a double wound electromagnet.
The other of the said primary windings I place in circuit with a battery and with
the other winding of the above mentioned double wound electromagnet.
When carrying my invention into effect I pass the currents from the two
batteries through the electromagnet and the mutual induction coil in one of two
manners; that is to say I (a) pass the two currents through the electromagnet in
the same direction and through the mutual induction coil in opposite directions, or
I (6) pass the two currents through the electromagnet in opposite directions and
through the mutual induction coil in the same direction.
Having now described my invention in general terms I shall proceed to show
how it can be practised or carried into effect and for that purpose I shall proceed
to describe it more in detail and with reference to the accompanying sheet of
drawings.
Figures 1 and 2 illustrate the method of carrying my invention into effect.

page_text: In these figures X is the mutual induction coil and Y the double wound electro-
magnet. T is the transmitter, B the transmitter battery and B the other battery,
which I shall hereinafter refer to as the reinforcing battery. c is the core of the
mutual induction coil and e¹ the core of the electromagnet. The mutual induction
coil is furnished with two primary windings P and P₁ and a secondary winding S,
which latter is connected to carth E and line L in the usual well known manner,
or to the two line wires of a metallic circuit. The electromagnet is furnished
with two windings W and W₁. The current from the transmitter battery R
traverses the primary P, the winding W, and the transmitter T as shown, whilst
the current from the reinforcing battery B₁ traverses the primary winding P¹ and
the winding W of the electromagnet as shown.
Figure illustrates the case in which the currents from the two batteries
traverse the electromagnet in the same direction and the mutual induction coil in
opposite directions; whilst Figure 2 illustrates the case in which I pass the two
currents through the electromagnet in opposite directions and through the mutual
induction coil in the same direction.
It is not necessary that the two batteries be entirely distinct. A single battery
may be used some of the cells of which are connected up in the transmitter circuit
and some in the reinforcing circuit.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:―
1. The method of telephonic transmission which consists in reinforcing the
current traversing a circuit containing a transmitter, one primary winding of a
mutual induction coil, and one winding of an electromagnet, by means of the
current traversing another circuit containing a second primary winding of the
same mutual induction coil and another winding of the same electro-magnet,
substantially as set forth.
2. The apparatus for telephonic transmisssion which consists in the combination
of a transmitter, a transmitter battery, a reinforcing battery, a mutual induction
coil with two primary windings and a double wound electromagnet, substantially as
and for the purpose set forth.
Dated this 21st day of Sentember 1899