IMPROVEMENTS IN ELECTRIC TELEPHONY
Year: 1885

page_text: I, JAMES GRIEVE LORRAIN of 3 Vernon Chambers, Southampton Row, in the
County of Middlesex, Consulting Engineer, do hereby declare the nature of my
invention for IMPROVEMENTS IN ELECTRIC TELEPHONY to be as follows:-
My invention consists in improvements in Electric Telephony and has for its
object the overcoming of certain difficulties which have so far stood in the way of
the successful employment of instruments worked by statical or similar high
potential electricity. When the Telephone instruments consist of condensers or
other so called statical instruments insulation is difficult and leakage troublesome,
and my invention is designed to overcome these drawbacks and obtain other
advantages.
In carrying my invention into effect I may employ in the cases where condensers
or other so called statical instruments are employed both as transmitters and
receivers, two secondary generators, or their equivalents, one of which may be
placed close to the transmitter and the other close to the receiver. By this means
the high potential electricity at the transmitter may be converted into a com-
paratively low potential current before being passed along the line wire, and again
by means of the secondary generator or its equivalent at the receiving station into.
high potential electricity so as to actuate the condenser or other so called statical
instrument used as a receiver. I may place these secondary generators in immediate
proximity, say in the same case, to the transmitter or receiver respectively. When
I use the condenser or other statical instrument as receiver only then I may place
the secondary generator at the receiving station instead of at the transmitting
station as now done. By this means the electric current is not transformed into
one of high potential until it reaches the receiver. I may combine the condenser,
or other statical instrument used as a receiver and the secondary generator in one
instrument or apparatus. Instead of employing a microphone transmitter to
actuate a condenser or other statical receiver as is now done, I may employ an
electromagnetic transmitter generating alternating currents.
1007

page_text: Improvements in Electric Telephony.
I, JAMES GRIEVE LORRAIN of Norfolk House, Victoria Embankment, London W.C.,
formerly of 3 Vernon Chambers, Southampton Row, in the County of Middlesex,
Consulting Engineer, do hereby declare the nature of my Invention for IMPROVE-
MENTS IN ELECTRIC TELEPHONY and in what manner the same is to be performed to
be particularly described and ascertained in and by the following statement:-
My invention consists in improvements in Electric Telephony and has for its
object the overcoming of certain difficulties which have so far stood in the way of
the successful employment of instruments worked by so called statical or other high
potential electricity when such instruments are used for transmitting as well as for
receiving. When the telephone instruments consist of condensers or other so called
statical instruments connected up and worked as at present insulation is difficult
and leakage troublesome. My invention is designed not only to overcome these
drawbacks but to obtain other advantages.
(a.) In the case wherein condensers or other so called statical instruments are
employed both as transmitters and as receivers, that is both for the purpose of
transmitting and receiving, I employ, in carrying my invention into effect, two
secondary generators, or as they may be more properly called induction coils or
converters. These secondary generators (hereinafter termed converters) may consist
of any known form or modification of inductional apparatus serving to convert
electricity of large current and low electromotive force into electricity of small
current and high electromotive force or vice versa. I here use the terms large and
small and high and low in a relative sense. I prefer to place one of these con-
verters at the transmitting station and the other at the receiving station. The one
at the transmitting station is so wound or constructed as to convert high tension
electricity into electricity. of low tension for the purpose of being passed along the
line wire, whilst the one at the receiving station is so wound or constructed as to
convert this comparatively low tension electricity into electricity of sufficiently high
tension to actuate the condenser or other so called statical instrument acting as a
receiver. By this means it will be seen that when traversing the line the electricity
is of comparatively low tension so that insulation is not so difficult nor leakage so
troublesome as if the electricity. traversing the line were of the high potential
required to actuate the transmitting and receiving instruments. I sometimes place
the converters in the same containing cases or boxes with the speaking instruments,
that is the converter which converts the electricity from high into low potential in
the same containing case as the transmitter, and the converter which converts
the electricity from low into high potential in the same containing case as the
receiver.
2
(b.) In a known system of telephony a condenser is used as a receiver and a micro-
phone or other similar instrument transmitting undulatory continuous currents is
used as a transmitter. It has hitherto been a drawback to this system that, owing to
the high tension of the current passed over the line, insulation has been difficult,

page_text: and leakage troublesome, whilst the inductive action of the current passing along
one line has affected other lines in the neighbourhood to such an extent as to
render their successful operation almost impossible. In the case where I make use
of this system, I employ, in carrying my invention into effect, only one converter
namely one so wound or constructed as to convert low into high tension clectricity;
and instead of placing this at the transmitting station as is at present, done in the
system I have referred to I place it at the receiving station, and connect it with
the transmitting station by means of its low tension circuit in which is the trans-
mitter and transmitter battery, so that the electricity passing along the line is
simply of the tension required to work the transmitter and its circuit.
(c.) In the known system of telephony herein before mentioned the receiving
instrument is actuated by an undulatory continuous current of electricity, that is,
by a current which, though caused to undulate or fluctuate, flows continuously in
one direction. A part of my present invention consists in actuating the receiving
instrument by an alternating current of electricity, that is, by a current alternately
flowing in opposite directions, and this I effect by using as a transmitter an electro-
magnetic instrument generating alternating currents. I find what is known as an
English mechanic or membrane telephone suitable for this purpose.
Having thus described my invention in general terms, I shall now, in order that
it may be better understood, proceed to describe it more in detail; and for this
purpose I shall refer to the several figures in the accompanying sheets of drawings
which diagrammatically illustrate typical instances of the carrying out of my
invention, and in which the same letters of reference indicate corresponding parts.
I however distinguish between the parts at the two different stations by indicating
those at one station by the simple letters and those at the other by the same letters
followed by a tick.
Figures 1, 2, 3 and 4 are diagrams illustrating the case referred to in paragraph (a).
In figure 1 the transmitting instrument is at station X and the receiving
instrument at station Y. T is the transmitting instrument arranged in the fine
wire or high tension circuit J of the converter A in which circuit is also the primary
battery D or other source or reservoir of high tension electrical energy serving to
charge the transmitting instrument. This circuit J is purely local and does not
extend between the two stations. K is the other or thick wire or low tension
circuit common to the two converters A and A¹. A¹ is the converter at station Y
and its high tension circuit J¹ has in it the receiving instrument R¹ and the source or
reservoir of high tension electrical energy D¹ used to charge it. The action is as
follows. The circuit J and the transmitting instrument T are highly charged by D
and this charge is varied by the action of the voice on T. This variation in J will,
as will be readily understood from the well known action of the converter, cause
similar variations to be set up in K but the electromotive force in K will be lower
than that in J. Similarly the variations in K will set up corresponding vibrations
in J¹ but the electromotive force in J' will be higher than that in K and these
variations will increase and decrease the charge in R¹ and cause it to emit sounds.
and speak.
Figures 2, 3 and 4 are diagrams somewhat similar to figure 1 except that in the
instances illustrated by these diagrams there are two instruments at each station
one for use as a transmitter and the other for use as a receiver. In figure 2 the
transmitting and receiving instruments are arranged in series with the charging
battery D in which case it will be seen that only one of the elements or series of
elements of T and of R are directly charged by the battery the other element or
series of elements being charged solely by induction. In figure 3 T and R are
arranged in parallel or multiple arc with D in which case it will be seen that both
elements or series of elements of T and R are directly charged and with electricity
of opposite sign by D. In figure 4 the circuit J is split into two parts (one being
practically a shunt or derived circuit from the other) in one of which is the trans-
mitter T and in the other the receiver R each provided with a separate battery.
The drawing of the connections at the two stations in this figure are different but

page_text: practically these two methods of connecting up are the same. In practice I prefer
to employ this method. The electromotive force required to actuate the instru-
ment as a transmitter is much higher than that required to actuate it when used as
a receiver.
Figures 5 and 6 are diagrams illustrating the case referred to in paragraph (b)
namely that in which a microphone or similar instrument is used as the transmitter
and a condenser or other statical instrument as the receiver.
Figure 5 represents the simplest form of installation namely that with a
transmitter alone at one station and a receiver only at the other. In this case
instead of having the converter at the same station as the transmitter (as is the
case in the known system of telephony hereinbefore referred to, in which the high
tension current required to actuate the condenser is sent along the line between the
two stations, so rendering insulation difficult and leakage troublesome), I place the
converter at the receiving station, leaving the line wire to form part of the low
tension circuit of the said converter in which are the microphone or other similar
transmitter and the battery required to actuate it. By this method it will be seen
that the only current traversing the line wire is the low tension one required to
actuate the transmitter. In this figure B. is the battery of comparatively low
potential serving to actuate the microphone transmitter.
Figure 6 is a diagram representing an instance similar in principle to that in
figure 5 except that there is a transmitter and a receiver at each station, the
transmitters being microphones or similar instruments and the receivers condensers
or other statical instruments as before. In such a case I connect up the instruments
as shown, the transmitters being in the low tension line circuit common to the two
converters, and the receivers being with their charging batteries in the high tension
local circuits. It will be seen that instead of having the high tension current
.necessary to charge the condenser or other statical instrument passing over the line,
the current which is sent over the line has only the comparatively low electromotive
force required for the transmitter circuit.
In the case mentioned in paragraph (b) the microphone or other similar
transmitter, under the influence of the sound waves produced by the voice which
impinge upon it, produces variations uniform with such sound waves in the current
passing through the low tension circuit of the converter. These variations of the
current in the low tension circuit of the converter set up similar variations in the
high tension circuit, which by increasing and decreasing the charge in the
condensers or other statical instruments cause them to emit sounds and speak.
The greater the variations in the charge of the condenser or other statical
instrument the more pronounced are the effects produced. When a microphone
or other similar transmitter producing undulatory continuous currents is employed
the difference of potential between the two elements or series of elements of the
condenser or other statical receiver is increased or diminished but I find it
advantageous instead of employing an undulatory continuous current, that is
one which although it varies flows always in the same direction, to employ an
alternating current because thereby alternations instead of mere variations in the
charge of the condenser are produced. Instead of the charge on each element or
series of elements of the receiver simply varying between being more or less
positive or more or less negative as the case may be, they alternate between being
positive and negative. The one element or series of elements of the receiver
alternates between being positive and negative whilst the other element or series
of elements alternates between being negative and positive. Increased and more
marked effects are thus obtained.
In carrying this part of my invention, which is that herein before referred to in
paragraph (c), into effect, I use as a transmitter au electromagnetic instrument
producing alternating currents, by preference an instrument of the type known as
an English mechanic or membrane telephone; and I prefer to connect it up in
circuit in the same manner as the microphone transmitter is connected up in
figures 5 and 6. Although I prefer so to connect it up yet when desired I may

page_text: connect it up as is the microphone transmitter in the known system of telephony
to which I have before referred.
The form of so called statical instrument which I prefer to use is one arranged
in the form of a singing condenser, or such form of condenser as is usually found
in the base of a sparking coil, and consisting 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 sheets of tin-foil being connected
together so as to form two series of elements or armatures with which the opposite
ends of the high tension circuit respectively communicate.
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. In the case wherein condensers or other so called statical instruments are used
both as telephonic transmitters and receivers the improvement in Electric Telephony
consisting in the use of two converters substantially as and for the purposes
set forth.
2. In the case wherein a condenser or other so called statical instrument is used
as a receiver and a microphone or other instrument transmitting undulatory
continuous currents is used as a transmitter the improvement in Electric Telephony
consisting in the use of a converter or converters so placed and arranged that the
line wire shall form part of the low tension circuit substantially as and for the
purpose set forth.
3. In the case wherein a condenser or other so called statical instrument is used
as a receiver and a microphone or other instrument transmitting undulatory
continuous currents is used as a transmitter the improvement in Electric Telephony
consisting in the placing of the transmitter or transmitters in the line wire circuit
substantially as set forth.
4. In the case wherein a condenser or other so called statical instrument is
employed as a receiver the improvement in Electric Telephony consisting in
the use of an electromagnetic transmitting instrument transmitting alternating
currents substantially as and for the purpose specified.
5. In a system of electric telephony the improvement consisting in the com-
bination of an electromagnetic telephone as transmitter and a singing condenser
as receiver substantially as described.
1000