Improvements in Electric Telephony
Year: 1886

page_text: Date of Application, 13th May, 1886.
Complete Left, 14th Feb., 1887.
Complete Accepted, 15th Mar., 1887.
I, JAMES GRIEVE LORRAIN, of Norfolk House, Norfolk Street, London, W.C.
Consulting Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to Improvements in Electric Telephony whereby certain
advantages are obtained.
A method of transmitting and reproducing speech electrically, discovered and
described by Mr. W. H. Preece, consists in utilising the heat generated in a wire
or conductor by the passage of a current of electricity through it. When such a wire
is placed in a receiver and connected with a microphone transmitter the variations of
intensity of the current sent from the microphone transmitter and passing through the
said wire causes similar variations in the temperature produced in the wire, the
temperature being raised to a greater or less extent according as a greater or less
amount of electrical energy is passed through the wire. These variations in the
temperature of the wire produce variations in the expansion of the air surrounding the
wire, and such variations of expansion may be caused to actuate a diaphragm and so
reproduce the sound vibrations actuating the transmitter. The effects produced by
this means are however too feeble for practical application.
The subject of my invention is somewhat similar to the above, to this extent at
least that I take advantage of thermal effects produced by the passage of electricity
through a conductor. My invention however differs from that of Mr. Precce in that
instead of relying upon variations of the amount of expansion I rely upon the
differences between expansion and contraction, so that a much greater range of effect
and amplitude of movement is obtained.
In carrying my invention into effect I may employ a receiving instrument consist-
ing of a close case fitted with a diaphragm. In this case I may have a compound
conductor consisting of two wires or pieces of dissimilar conducting substances
soldered together or otherwise in intimate contact with one another. To obtain
the greatest effect I may employ substances as far apart as possible on the thermo-
electric scale or series one being highly electro-positive and the other highly electro-
negative. The two constitutents of the compound conductor may be of any

page_text: convenient size or shape and they may be in contact with each other by simple pressure
or by rolling or twisting together or by soldering binding or the like. In order to
actuate this receiving apparatus I employ a transmitter generating alternating currents
that is one which instead of varying the amount of electrical energy transmitted to
the receiver, which is the action of the microphone transmitters now in use, causes
currents alternating in direction to be transmitted.
The action of my invention is as follows:-When a current of electricity is sent
from the transmitter through the junction of the two conductors constituting the
compound conductor in the direction of the electro-negative to the electro-positive
conductor the temperature of the junction is raised, and when the current is sent
through the junction of the two conductors constituting the compound conductor in
the direction of the electro-positive to the electro-negative conductor the temperature
of the junction is lowered. The effect of the alternate raising and lowering of the
temperature of the junction is to alternately expand and contract the air surrounding
it, and such alternation of expansion and contraction of the air in the receiver case will
cause alternations of pressure on the diaphragm so causing it to vibrate in unison with
the vibrations of the transmitter, and reproduce the speech after the usual manner in
telephony.
COMPLETE SPECIFICATION.
Improvements in Electric Telephony.
1 JAMES GRIEVE LORRAIN of Norfolk House, Norfolk Street, London W.C.
Consulting 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:—
My invention relates to improvements in Electric Telephony whereby certain
advantages are obtained.
A method of transmitting and reproducing speech electrically, discovered and
described by Mr. W. H. Precce F.R.S. consists in utilizing the heat generated in a
wire or conductor by the passage of a current of electricity through it. When such
a wire is placed in a receiver and connected with a microphone transmitter the
variations of intensity of the current sent from the microphone transmitter and passing
through the said wire causes similar variations in the temperature produced in the
wire the temperature being raised to a greater or less extent according as a greater or
less amount of electrical energy is passed through the wire. Those variations in the
temperature of the wire produce variations in its linear expansion. Thus if one end

page_text: of the wire he attached to the centre of a diaphragm and the other end be attached to
a fixed point or to an adjustable screw or the like the said variations in the expansion
of the wire will produce variations in the tension upon the diaphragm thus causing it
to vibrate and so reproduce the sound vibrations actuating the transmitter. This
form of telephone is fully described and illustrated in the paper communicated by
Mr. Preece to the Royal Society on April 28th 1880.
The subject of my invention is somewhat similar to the above to this extent at
least that I take advantage of thermal effects produced by the passage of electricity
through a conductor. My invention however differs from that of Mr. Precce in that
instead of relying upon variations in the amount of expansion I take advantage of
what is known to Electricians as the Peltier effect by which I rely upon the differences
between direct expansion and direct contraction caused by positively produced heat
and cold depending upon the direction in which the current of electricity is passed
through the junction of a compound conductor as hereinafter described so that a much
greater range of effect and amplitude of movement is obtained.
x
In carrying my invention into effect 1 employ a receiving instrument consisting of
a closed case fitted with a diaphragm. In this case I have a compound conductor
consisting of two wires or pieces of dissimilar conducting substances soldered together
or otherwise in intimate contact with one another. To obtain the greatest effect
I prefer to employ substances as far apart as possible on the thermo-electric scale or
series one being highly electro-positive and the other highly electro-negative. The
two constitutents of the compound conductor may be of any convenient size or shape
and they may be in contact with each other by simple pressure or by rolling or
twisting together or by soldering binding or the like. In order to actuate this
receiving apparatus I employ a transmitter generating alternating currents that is one
which instead of varying the amount of electrical energy transmitted to the receiver
(which is the action of the microphone transmitters now in use) causes currents
alternating in direction to be transmitted.
:-
The action of my invention is as follows: When a current of electricity is sent
from the transmitter through the junction of the two conductors constituting the
compound conductor in the direction of the electro-negative to the electro-positive
conductor the temperature of the junction is raised, and when the current is sent
through the junction of the two conductors constituting the compound conductor in
the direction of the electro-positive to the electro-negative conductor the temperature
of the junction is lowered. The effect of the alternate raising and lowering of the
temperature of the junction is to alternately expand and contract the compound wire
when it is arranged in the same manner as the simple wire used in Mr. Preece's
telephone or to cause expansions and contractions of the air in the receiver when
arranged as illustrated in the accompanying drawings which will cause alternations of
stress on the diaphragm so causing it to vibrate in unsion with the vibrations of the
transmitter and reproduce the speech after the usual manner in telephony. It will
be readily understood that the wire away from the joint is heated independently of
the direction in which the current is passed such heating being due not to any Peltier
effect but to the resistance offered to the passage of the current. In the case however
where the wire is arranged in the manner of Mr. Preece's wire the effect of my
invention is still advantageous whilst in the case wherein I arrange the compound wire
as shown in the accompanying drawings wherein the diaphragm is caused to vibrate
by the expansion and contraction of the air I get over any difficulty arising through.
the heating of the wire at such parts which are away from the junction by covering
such parts with a non-conductor of heat.
It will be understood that in the case wherein the diaphragm is caused to vibrate
by the expansion and contraction of the compound conductor attached to it instead of
by means of the expansion and contraction of the air it is not necessary that the
containing case of the instrument should be entirely closed.
In the accompanying drawings which in order to be more readily understood are
diagrammatic rather than illustrative of actual apparatus the compound conductor is
in each case shown as a wire or strip but I desire it to be understood that I do not

page_text: limit myself to wires or strips but may make the compound conductors of any size or
shape desired and such size or shape will depend as a rule on the nature of the materials
employed in each particular case.
Figure 1 is a cross section through the centre of one form of telephone constructed
according to my invention. A and B are wires or strips of dissimilar substances consti-
tuting the compound conductor. C is a diaphragm of any suitable material such as
ivory celluloid wood iron or the like and D is a containing case formed of wood ebonite
or other suitable material. J is the joint formed between the two dissimilar wires or
strips constituting the compound conductor and it is made by soldering or otherwise
as hereinbefore mentioned. The compound conductor is covered by any suitable
substance E which is a good non-conductor of heat except at the part where the joint J
is situated. Fand G are terminal pieces for the attachment of the ends of the
compound conductor or of wires or strips H K connected therewith.
Figure 2 is a section of another form of telephone constructed according to my inven-
tion In this case the compound conductor is composed of several pairs of pieces of two
dissimilar substances A. A and B B which are placed alternately in continuous electrical
connection and bent at the joints into a zigzag form as shown. The compound
conductor thus constructed is embedded in any suitable non-conductor of heat E but
all the joints are uncovered. It will be seen that the joints J, J, J, J¹, taken in order
are alternately in the space F inside the case D below the diaphragm Cand in the other
space G which is formed between the partition H and a perforated plate or gauze K.
The joints in the two spaces are marked JJ and JJ respectively. When the joints J
produce heat the joints J¹ produce cold and vice versa but the partition H and the
non-conductor of heat E prevent the diaphragm C from being influenced by other
than the one set of junctions J. For convenience of illustration I have only lettered some
of the joints or junctions but it will be readily understood that all the joints in the
space F are referred to by the letter J and all the joints in the space G are referred
to by the letter J¹.
Figures 3 and 4 are respectively a plan and section of another form of my inven-
tion. The lettering of each part is the same as in figure 2 and the same description
is entirely applicable the only difference between the two forms being that in figures 3
and the compound conductor in its zigzag form after the manner shown in figure 2
is arranged in a circle so that it occupies a position immediately under the centre of
the diaphragm which position is the most suitable one to produce the vibration of the
diaphragm.
Having now particulary 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. The improvement in Electric Telephony consisting in the utilization of what is
known to Electricians as the Peltier effect substantially as set forth.
2. The improvement in Electric Telephony consisting in the combination of a
transmitter transmitting alternating currents and a receiver whose action depends
on what is known as the Peltier effect substantially as set forth.
3. The improvements in Electric Telephony consisting in the combinations of
parts constituting the receiving instruments substantially as set forth with reference
to figures 1, 2, 3 and 4 respectively.