IMPROVEMENTS IN ELECTRIC TELEPHONY
Year: 1882

page_text: LETTERS PATENT to James Grieve Lorrain of 2 Victoria Mansions in the
City of Westminster, Civil Engineer for an Invention of "IMPROVEMENTS IN
ELECTRIC TELEPHONY " Communicated to him from abroad by Albert
Dunand of Paris in the Republic of France, Professor of Mathematics
PROVISIONAL SPECIFICATION left by the said James Grieve Lorrain
at the Office of the Commissioners of Patents on the 20th June 1882.
13
JAMES GRIEVE LORRAIN of 2 Victoria Mansions in the City of Westminster,
Civil Engineer, "IMPROVEMENTS IN ELECTRIC TELEPHONY' A communication
to me from abroad by Albert Dunand of Paris in the Republic of France,
Professor of Mathematics.
This Invention relating to Improvements in Electric telephony has reference to
an arrangement and combination of apparatus, whereby articulate speech may be
transmitted and reproduced with greater clearness and intensity than heretofore.
In carrying out this Invention a condenser or series of condensers such as that
used in the base of an induction coil, are employed as the receiving telephone, in
combination with a battery, both arranged in the circuit of the secondary wire of
an induction coil, a microphonic or other transmitter with its battery being
arranged in the primary wire of the said coil.
The current from the transmitter battery passes through the circuit of the
primary wire of the Induction coil and this current is modified under the action of
the voice by the transmitter interposed in this circuit. One armature of the
receiving condenser communicates with one extremity of the secondary wire
the second armature with one of the poles of the receiver battery whose other pole
is connected to the other extremity of the secondary wire. When both a
transinitter and receiver are required at the same station, an induction coil is
used at each station its primary wire containing the transmitter and transmitter

page_text: battery as hereinbefore described, whilst the two receiving condensers are arranged
in the secondary wire of the two coils with a single receiver battery common to
the two or a receiver battery for each may be employed if found desirable
The condensers may be arranged in various forms, and when two or more are
employed, connected up by preference in quantity the intensity of the sounds is
increased. When two condensers are used they may be so arranged as to he
placed one at each ear or they may be located in a box or case provided with
acoustic tubes if desired. When a greater number of condensers is used they may
be arranged to radiate fanwise and be fixed at the converging ends to a board or
on a sounding box. The condensers may be used both as transmitter and as
receiver.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Grieve Lorrain in the Great Seal Patent Office on
the 20th December 1882.
JAMES GRIEVE LORRAIN of 2 Victoria Mansions in the City of Westminster
Civil Engineer "IMPROVEMENTS IN ELECTRIC TELEPHONY " A communication
to me from abroad by Albert Dunand of Paris in the Republic of France
Professor of Mathematics.
The said Invention relating to Improvements in Electric Telephony has reference
to an arrangement and combination of apparatus whereby articulate speech may
be transmitted and reproduced with greater clearness and intensity than heretofore.
In carrying out the said Invention a coudenser or series of condensers such as
that used in the base of an induction coil is employed as the receiving telephone
in combination with a battery, both arranged in the circuit of the secondary wire
of an induction coil a microphone or other transmitter with its battery being
arranged in circuit with the primary wire of the said coil.
In order that the said Invention may be perfectly understood 1 shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures in the accompanying sheet of drawings the same letters of
reference indicating corresponding parts in all the figures.
Figure 1 is a diagram illustrating the simplest arrangement of the apparatus
videlicit that in which a single instrument only (transmitter or receiver as the case
may be) is used at one station. Figures 2, 2 and 2b illustrate arrangements in
which both a transmitter and a receiver are employed at each station. Figures 3,
4, 5, 6, 7 and 8 illustrate as typical examples various arrangements of compound
condensers which may be used Figure 3 being a front elevation and Figure ta
longitudinal section of one form of compound condenser and Figures 5 and 7
respectively longitudinal sections and Figures 6 and S plans of two other forms
(drawn to a smaller scale than Figures 3 and 4).
Referring to Figure 1 A represents a microphone or other transmitter arranged
in the circuit of the battery B and primary wire a of the small induction coil Cat
the transmitting station; b is the secondary wire of the said coil one end of which
communicates with the line and with a battery D and thence with one of the two
series of plates or armatures forming the condenser E which constitutes the receiver
at the receiving station the other end of the secondary wire communicating with
the other series of plates or armatures of the condenser.
The current from the battery B passing through the primary wire of the
induction coil is modified or varied under the action of the voice by means of the
microphone or other transmitter A interposed in this circuit. This variation or
undulation of the current in the primary circuit causes electrical variations or
undulations to be set up in the secondary wire which increases or decreases the
charge of the condensers causing them to speak or emit sounds.
When both a transmitter and receiver are required at the same station an
induction coil is used at each station its primary wire containing the transmitter
and transmitter battery as hereinbefore described whilst the two receiving
condensers arc arranged in the circuit of the secondary wire of the two coils with a
single battery in the same circuit common to the two or a battery for each may
be employed if found desirable.
One mode of carrying out this arrangement is illustrated in Figure 2 in which
two condensers EE (one for each station) are shewn as interposed in the secondary
wire b common to the two induction coils C C a single battery D being employed
in the circuit of the secondary wire.

page_text: When a separate battery for each station is employed they are arranged in the
secondary circuit as shewn in Figure 2ª the battery Ď being placed in one part of
the secondary circuit between the receivers EE and the battery D' in the other
part of the said circuit; the positive and negative poles of the batteries are so
connected with the receivers that the positive of one battery and the negative of
the other are connected with the two series of plates of each condenser as shewn
in figure 2ª.
I prefer however to place a single battery in the secondary circuit as shown in
Figure 2b wherein it will be seen that the battery is substantially arranged in a
shunt or derived circuit from the secondary circuit the essential condition in this
case being that the condensers at each end or station are arranged to be charged in
quantity by the battery and are not as in the preceding cases (figures 2 and 2)
arranged in series with the battery or batteries.
The condensers employed are of the kind used in the base of induction coils as
before mentioned and consist of thin sheets of a conducting material such for
example as tin foil alternating with thin sheets of insulating material such for
example as paper, a sheet of tin foil being interposed between each two sheets of
paper and the alternate plates of tin foil being connected together so as to form
two series of plates or armatures with which the opposite ends of the secondary
wire respectively communicate as hereinbefore explained.
Although however I have in all cases found it desirable to use condensers of the
generic character hereinbefore referred to, yet it should be understood that the
details of construction and the shape and arrangement of the condensers may be
varied to an almost indefinite extent.
In practice 1 have found that the condensers which give the best results are
those composed of alternate sheets of tin foil and thin paper such for example as
tissue paper or the paper may be dispensed with and the leaves of tin foil be
insulated by a varnish The two exterior surfaces of the condenser are by
preference formed of a thin sheet of strong sonorous material such for example as
card board, vulcanite, glass, celluloid, or metal, which may be provided with an
opening.
A suitable number of insulated sheets of tin foil connected up and provided with
a resistant and sonorous facing and backing as hereinbefore described may be
used as a receiver without any additional ear piece or other appendages.
Good results have been obtained with the use of from 30 to 40 of the insulated
sheets of tin foil in a single receiver but the number may be varied.
The result is rendered still more satisfactory by combining in a single receiver
two of such condensers connected up in quantity and arranged so that each may
be conveniently placed against an ear.
When more intense sounds are required capable of being heard at a distance I
combine in a single receiver say five six or more of the condensers connected up
in quantity in which case the number of sheets of tin foil in each condenser may
be advantageously reduced. The multiple condensers so combined together may bo
arranged in boxes or otherwise in various ways according to the exigencies of
particular cases
I have shewn in Figures 3 to S of the accompanying sheet of drawings three
examples of the methods in which a number of condensers may be combined
together in a single instrument but many other modifications suitable for special
circumstances will readily suggest themselves to those skilled in the art.
In the arrangement represented in Figures 3 and 4 the condensers d d d are
disposed parallel to each other a short distance apart in a box F; the alternato
sheets of tin foil are respectively connected at the opposite sides by wires 1-2
with the two binding screws 3-4 communicating with the two extremities of the
secondary wire of the induction coil, a battery being interposed in the circuit as
herein before described. On one side of the box F is a cover c with an opening f
which may be placed against one ear; on the other side is a cover c¹ having an

page_text: opening over which may be fixed a flexible acoustic tube to be applied to the
other car.
Another modification in the arrangement of the multiple condensers is illustrated
in Figures 5 and 6 in which a number of condensers d d d are arranged in such
a manner as to be in contact along their side 5 and then to radiate from each
other fanwise so as to be separated on their other sides a short distance. The
condensers are fixed at the side 5 in any convenient manner on a board or
sounding box F and are connected up in quantity as herein before explained.
With this arrangement of apparatus it is not necessary to place the instrument
directly to the car as transmitted articulate sounds can be distinctly heard at
several yards distance.
According to a further modification which is illustrated in Figures 7 and 8 five
condensers d d d d d' connected up in quantity as herein before described are
combined together in such a manner that one d¹ forms a bottom and the four d d
dd form the sides of a species of funnel shape box which causes sounds electrically
transmitted to be heard at a considerable distance as in the modification last
berein before described. In these figures the connections are omitted for the sake
of clearness of illustration.
Although I prefer to connect the several condensers forming the compound
condenser up in quantity as herein before described yet they may be connected up
in series if desired.
The battery which charges the condenser consists of a number of cells connected
up in tension. When only one condenser is used or two joined up in quantity
say from five to ten battery cells connected up in tension will usually be found
sufficient but when a larger number of condensers is employed in the receiver
joined up in quantity the number of cells in the condenser battery, connected up
in tension, should be augmented, it being found that the sounds emitted increase
in intensity with the number of condensers and the number of battery cells
employed.
The induction coil used may be composed simply of a primary wire and a
secondary wire without any condenser in its base.
Having now described and particularly ascertained the nature of the said
Invention and the best methods with which I am acquainted of carrying the same
into effect I would observe in conclusion that I am aware that it has been
previously proposed to employ a condenser or series of condensers as a receiver in
electric telephony and therefore to this in itself I lay no clain but what I consider
to be novel and original and therefore claim as the Invention secured to me by
the hereinbefore in part recited Letters Patent is :-
First The employment of a battery or batteries in combination with a condenser
or series of condensers used as a receiving telephone, the said battery or batteries
and condenser or series of condensers being both arranged in the circuit of the
secondary wire of an induction coil, substantially as herein before described.
Second-The peculiar arrangement of compound condensers substantially as
herein before described with reference to Figures 5 and 6 of the accompanying
drawings.
In witness whereof I the said James Grieve Lorrain have to this my
Specification set my hand and seal this nineteenth day of December One