IMPROVEMENTS IN AND RELATING TO TELEPHONIC APPARATUS
Year: 1883

page_text: LETTERS PATENT to George Lee Anders of Queen Victoria Street in the City
of London for an Invention of "IMPROVEMENTS IN AND RELATING TO
TELEPHONIC APPARATUS"
PROVISIONAL SPECIFICATION left by the said George Lee Anders at the
Office of the Commissioners of Patents on the 13th October 1883.
GEORGE LEE ANDERS, of Queen Victoria Street, in the City of London,
"IMPROVEMENTS IN AND RELATING TO TELEPHONIC APPARATUS
"3
My invention relates to telephonic receivers and to methods of connecting the
same with the line and with the batteries and other apparatus necessary for its
effective operation
My improvements are designed to obviate the necessity heretofore experienced of
using a permanent magnet as part of the receiving instrument in cases where the
transmitting microphone is not connected in the main line circuit but influences
the latter through the medium of an induction coil such permanent magnets being
both heavy and costly.
To this end I combine two simple electro-magnetic receivers (such for example as
those described in "The English Mechanic and World of Science" for August 11th
1876) or two or more coils or parts of coils forming part of a single receiver of this
kind with two galvanic batteries and with the line in the following manner, that is
to say: I connect the two receivers or the two coils or parts or sets of coils of a
single receiver severally to two galvanic batteries, making the connection to the
positive pole of one of the batteries and to the negative pole of the other battery,
and I then connect the free poles of the two batteries to earth and the free terminals
of both the receivers or of the two coils or parts or sets of coils to the line, including
in the circuit such other apparatus as may be necessary according to well-known
systems as applied to other telephones now in use.
It is however necessary to modify the usual connections in such a manner that
the circuits of both the batteries attached to the receivers may be open when the
instruments are not in use For this purpose I prefer to place two contact springs

page_text: near the usual automatic switch, the latter being as usual connected to line, and to
connect one receiver to each spring so that when the switch is relieved from the
weight of the telephone it may make contact with both the said springs and thus
connect both telephones to line as above described but when the switch is depressed
by hanging the telephone thereon, it will leave the said springs and thus open both
the battery circuits as desired.
In the case where a single receiver only is used I may add a further coil or coils
through which the line current passes but not the battery current, all the coils of
the receiver or receivers however as well as the batteries connected with them
being in every case included in the circuit through which the line current must
pass

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Lee Anders in the Patent Office on the 12th April 1884.
GEORGE LEE ANDERS, of Queen Victoria Street in the City of London
"IMPROVEMENTS IN AND RELATING TO TELEPHONIC APPARATUS
"
My invention relates to telephonic receivers and to methods of connecting the
same with the line and with the batteries and other apparatus necessary for their
effective operation.
My improvements are designed to obviate the necessity heretofore experienced of
using a permanent magnet as part of the receiving instrument in cases where the
transmitting microphone is not connected in the main line circuit but influences the
latter through the medium of an induction-coil, such permanent magnets being both
heavy and costly.
To this end I combine two simple electro-magnetic receivers (such for example
as those described in "The English Mechanic and World of Science" for August 11th
1876) or two or more coils or parts of coils forming part of a single receiver of
this kind, with two galvanic batteries and with the line in the manner hereinafter
described.
In the accompanying drawing
Figure 1 is a diagram showing two receivers and two batteries arranged in
connection with the line wira
Figure 2 is a similar view but showing in section a single receiver provided with
three coils and hereinafter described.
Similar letters of reference indicate corresponding parts in both Figures.
a a' indicate two receivers connected respectively to the two galvanic batteries,
bb by the wires c c¹ the wire c being connected to the positive pole of the battery b
and the wire c¹ to the negative pole of the battery b¹. The other poles of the two
batteries are connected by the wires d d¹ to the contact pieces e e¹ of the automatic
switch fand the free terminals g, g¹ of the receivers are connected to earth as shown.
Such other apparatus as may be necessary according to well known systems as
applied to other telephones now in use is or may be included in each part of the
receiver circuit in order to render the resistance in the said parts uniform.
With this arrangement it will be seen that the circuit of the batteries and
receivers is open when the instruments are not in use, one of the said instruments
being then hung upon the hook of the switch fand the line wire being grounded
through the call bell h and wire i.
When the switch fis relieved from the weight of the telephone it makes contact
with the two contact pieces e, e¹ thereby closing the receiver circuit and magnetizing
the cores of the receivers, and at the same time connecting both receivers to line.
The line current has now two passages to earth but as the same resistance exists in
each portion of the receiver circuit between the contact pieces e, e¹ and the earth,
one half of the line current passes through the 1sceiver a and the other half through
the receiver a¹.
The line current passing through one part or branch of the receiver circuit
augments or reinforces the current produced by the battery therein while the said
line current opposes and decreases the current of the battery in the other branch. It
will thus be seen that according to the direction of the current in the main line
circuit the magnetism of one receiver will be increased while that of the other is
diminished.
The effect of the above described arrangement is that the instruments will be
sensitive to very slight variations of the main line current.

page_text: In the modification shown in Figure 2 the arrangement of circuits is substantially
the same but in this case a single receiver only is employed.
The said receiver is provided with two magnets k, k¹ attached to a metal plate
which magnets correspond with the magnets of the receivers a a¹ hereinbefore
mentioned.
The magnetic metal of the diaphragm m which is preferably composed of two
pieces of paper, membrane or similar material having the said magnetic metal
between them as in the receivers a a¹, is large enough to be acted upon by both
magnets kk' the poles of which are placed close to the said diaphragm. The said
magnetsk k¹ are wound in such a manner that both poles adjacent to the diaphragın
are of one polarity. Between the magnets k k¹ is placed a third magnet n through
the coils of which only the line current passes. This magnet is connected to the
plate and presents to the diaphragm a pole of opposite polarity to that of the
magnets k ki.
All the coils of the receiver as well as the batteries connected with them are in
every case included in the circuit through which the line current must pass.
In the operation of this receiver the two magnets k, k¹ draw the diaphragm m
towards them and tend to stretch it, so that the pulsations of current in the
magnet n will more readily produce vibrations of the said diaphragm.
:
I wish it understood that I do not limit myself to the precise arrangement of the
batteries and connections shewn in the accompanying drawing but may modify or
change the same to any extent which will not impair their efficiency for the purpose
of my invention.
Having thus fully described my said Invention and the manner of performing
the same I wish it understood that I claim.
First: The combination with the main line circuit of a telephone system, of a
receiver or receivers and batteries arranged substantially as herein described so that
all main line currents shall pass through them, for the purpose set forth.
Second-The telephone receiver provided with two electro-magnets included in
a circuit containing two batteries, and with a third electro-magnet. which is
magnetized by the line current, substantially as, and for the purpose, set forth.
In witness whereof I the said George Lee Anders have hereunto set my hand
and seal this tenth day of April in the year of our Lord One thousand eight
hundred and eighty four.
GEORGE LEE ANDERS (18)