IMPROVEMENTS IN TELEPHONY
Year: 1884

page_text: I. JAMES GRIEVE. LORRAIN of The Whitehall Club, Parliament Street in the
City of Westminster Consulting Engineer do hereby declare the nature of my
Invention for IMPROVEMENTS IN TELEPHONY to be as follows:--
In carrying my invention into effect I employ a transmitting instrument for, so
to speak, converting the mechanical vibrations produced by the voice into electrical
pulsations or undulations, and a receiving instrument for reconverting such
electrical pulsations or undulations into mechanical vibrations.
My transmitter may consist of a condenser or accumulator formed of two plates
or masses of metal or other suitable material insulated from one another by a
stratum of air or a layer or layers of varnish or of paper or of other suitable material.
One of these plates or masses, hereinafter called the back plate, may be connected
to the line going to the receiving instrument. The other plate or mass, hereinafter
called the moveable plate, may be connected to earth. One of the plates or masses,
preferably the back plate, may be charged with electricity by any suitable means,
for example by a dry pile or by a rod formed of two dissimilar metals soldered
together or by a charge from a proof plane or otherwise.
My receiver consists of an apparatus resembling in principle what is known as a
"gold leaf electroscope." In its simplest form this consists of two sheets or strips
of metal or other suitable material joined together at one edge. When electrified
these sheets or strips repel one another. The greater the charge of electricity the
greater the repulsion between them, the less the charge the less the repulsion.
My apparatus acts as follows. The back plate of the transınitter being charged,
the sound waves produced by the voice may be made to impinge upon the other
or moveable plate so as to make it approach to and recede from the back plate.
As the moveable plate recedes from the back plate the capacity of the latter is
decreased & therefore its potential is raised. As the moveable plate approaches the
back one the capacity of the latter is increased and its potential lowered. The
electroscope receiver being in connection with the back plate, the sheets or strips
will diverge more as the potential rises & less as the potential falls, thus producing
vibrations in unison with those at the transmitter.
In practice I prefer to employ a receiver of a more complex form than that
above described. Instead of using only two sheets or strips I may employ a
considerable number connected together at one or more edges, and I prefer to

page_text: separate each sheet or strip from that on either side by thin sheets of paper, mica,
talc, or other suitable material. In the construction of my receiver I prefer to
employ tinfoil & thin paper as materials.
I may connect the transmitter and receiver by a single wire, using neither earth
return nor metallic circuit. Or I may use a return wire or metallic circuit, or
earth connections or earth return. In any of these cases may place a battery or
other source of electricity in circuit or in a derived or shunt circuit.
I may interpose an induction coil between the transmitter & the receiver,
placing the transmitter in the primary circuit and the receiver in the secondary, or
vice versa, but preferably the former. When I use an induction coil I may place a
battery or other source of electricity in the same circuit as the receiver or in a
shunt or derived.circuit. therefrom,, and I may also place one in the same circuit as
the transmitter or in a shunt or derived circuit therefrom. When I place a battery
or other source of electricity in a shunt or derived circuit I prefer to employ a
switch to open the battery circuit when the apparatus is not in use.
F
I may use either plate or mass of the transmitter as the back plate and either as
the moveable plate. I may charge either the back plate as above described or the
moveable plate, & I may connect either to earth. I may cause the sound waves to
impinge upon either plate or mass.
I may duplicate or multiply the parts of the transmitter so as to gain increased
effect; & I may make the plates or masses of any convenient form.

page_text: COMPLETE SPECIFICATION.
I, JAMES GRIEVE LORRAIN, of The Whitehall Club, Parliament Street, in the
City of Westminster, Consulting Engineer, do hereby declare the nature of my
invention for IMPROVEMENTS IN TELEPHONY, and in what manner the same is to
be performed, to be particularly described and acertained in and by the following
statement:-
My invention relates to Improvements in Telephony whereby certain advantages
are obtained.
In carrying my invention into effect I employ a transmitting instrument for, so
to speak, converting the mechanical vibrations produced by the voice into electrical
pulsations or undulations, and a receiving instrument for reconverting such electrical
pulsations or undulations into mechanical vibrations.
My apparatus is based on the principle of the instrument known as the condensing
electroscope, my Transmitter being represented in that instrument by the condenser,
and my Receiver by the gold leaves.
In the drawing accompanying this specification Fig I shows the usual form of
condensing electroscope.
Fig 2: shows one form of my apparatus, the two figures being similarly lettered
to show the parts which correspond in principle.
In Fig I, J is a glass jar having suspended within it two narrow strips of gold
leaf B B by means of a brass rod inserted through a cork fitting the mouth of the
jar. The upper end of the rod is provided with a round plate of metal P, varnished
on its upper surface. On this rests another and similar plate P¹, furnished with an
insulating handle and varnished on its lower surface so that the two plates are
insulated from each other. A A¹ are two strips of metal opposite the gold leaves
and which are not insulated. When the gold leaves are charged they inductively
electrify these strips of metal, which then attract the gold leaves causing them to
diverge more widely. These strips thus render the instrument more sensitive than
it otherwise would be..
C is a metal cap surrounding the upper part of the glass jar and is uninsulated.
This shields the gold leaves from external inductive effects which might interfere
with their action.
The action of the condensing electroscope is as follows:-
Suppose the two plates to be charged and the upper one to be lifted by the
insulating handle, the capacity of the lower plate is greatly diminished, and the
potential of its charge rises causing the gold leaves to diverge.
If the upper plate be again lowered the capacity of the lower plate increases, and
the potential of its charge decreases, causing the gold leaves to come together
again. Any approach or recession of the moveable plate causes a corresponding
action in the gold leaves.
In Fig 2, which must be considered as diagramatic rather than as exactly illustra-
tive of the actual instruments, X represents the Transmitter and Y the Receiver.
B B' are discs of tinfoil corresponding to the gold leaves of the electroscope and
which are in contact at their edges, but which for clearness of representation are

page_text: shewn apart in the drawing. These foils have discs of thin paper or other suitable
material between them to prevent sticking. A A¹are thin plates of metal insulated.
from the tinfoil and serving the same purpose as the strips of metal A A' in the
electroscope. C is a metal case clamping the whole together, and acting together
with A A¹ as a shield to external inductive influences in the same way as the
metal cap C in the electroscope. D is a terminal in contact with the tinfoil discs.
In this figure I have for convenience of illustration shewn the leaves of the
Receiver as separate and parallel, whereas in reality they would be, in the instru-
ment illustrated, in actual contact all round their circumferences.
In the Transmitter P. P¹ are two discs of metal insulated from each other, and
. corresponding to the condenser plates P P¹ in the electroscope.
i
The terminals T T¹ are in connection with P and P¹ respectively.
E is the Transmitter case.
My Transmitter may consist of a condenser or accumulator formed of two or
more plates or masses of metal, or other suitable conducting material, insulated
from one another by a stratum of air, or a layer or layers of varnish, or of paper, or
other suitable material.
One of these plates or masses, hereinafter called the back plate, may be connected
to the line going to the receiving instrument. The other plate or mass, hereinafter
called the moveable plate, may be connected to carth.
One of the plates or masses, preferably the back plate, may be charged with
electricity by any suitable means; for example by a dry pile, or by a rod formed
of two dissimilar metals soldered together, or by a charge from a proof plane or
otherwise.
My Receiver consists as already mentioned, of an apparatus resembling in
principle what is known as a "gold leaf electroscope."
My apparatus acts as follows:-
The back plate of the Transmitter being charged the sound waves produced by
'the voice may be made to impinge on the other or moveable plate, so as to make it
approach to and recede from the back plate.
As the moveable plate recedes from the back plate the capacity of the latter is
decreased, and therefore its potential is raised. As the moveable plate approaches
the back one the capacity of the latter is increased, and its potential lowered.
The electroscope Receiver being in connection with the back plate, the sheets or
strips will diverge more as the potential rises, and less as the potential falls, thus
producing vibrations in unison with those at the Transmitter..
In practice I prefer to employ a Receiver of a more complex form than that above
described. Instead of using only two sheets or strips I may employ a considerable
number connected together at one or more edges, or the whole of their circum-
ferences may be in contact or electrical connection, leaving only their central parts
free to vibrate towards and away from each other after the manner of diaphragms.
In order to prevent sticking I may separate each sheet or strip from that on
either side by thin sheets of paper, or by a nonconducting and non-adhesive
powder such as French chalk, or by thin sheets of mica, talc, or other suitable
material.
I may place two metal-discs one on each side of my electroscope Receiver, and
close to each of the outer leaves to serve the same purpose as the two metal strips
A A¹ in Fig I.
I may perforate one or both of these to allow of the passage of the sound waves
produced by the Receiver. I may also surround the whole or part of my Receiver
by a case of metal or other suitable material. to shield it from external inductive
effects, thus serving the same purpose as the metal cap C in Fig Ę
This shield, as also the metal discs above mentioned, may be connected to earth,
or which will frequently answer the same purpose held in the hand!
I may connect the Transmitter and Receiver by a-single wire, using neither earth
return nor metallic circuit..

page_text: Or I may use a return wire or metallic circuit, or earth connections or earth
return. In any of these cases I may place a charging battery in circuit, or in
a derived or shunt circuit.
I may interpose an induction coil between the Transmitter and the Receiver,
placing the Transmitter in the primary circuit and the Receiver in the secondary,
or vice versa, but preferably the former. When I use an induction coil I may
place a charging battery in the same circuit as the Receiver, or in a shunt or derived
circuit therefrom, and I may also place one in the same circuit as the. Transmitter,
or in a shunt or derived circuit therefrom.
When I place a charging battery in a shunt or derived circuit, I prefer to employ
a switch to open the battery circuit when the apparatus is not in use.
This switch may be an automatic one caused to act by the addition or removal
of the Transmitter, or Receiver, or calling apparatus.
I may use either plate or mass of the Transmitter as the back plate, and either
as the moveable plate.
I may charge either the back plate as above described, or the moveable plate,
and I may connect either to earth or to line.
I may cause the sound waves to impinge upon either plate or mass.
may.duplicate or multiply the parts of the Transmitter so as to gain increased
effect, and may make the plates or masses of any convenient form.
My Receiver as above described can be also used as a Transmitter, its action in
that case being readily understood.
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 a telephone the electroscopic instrument substantially as and for the
purpose set forth.
2. In a telephone the combination of a condenser as transmitter and an electro-
scopic instrument as receiver substantially as set forth.
3. In a telephone the combination of an electroscopic instrument and a charging
battery substantially as and for the purpose set forth.
4. In a telephone the combination of a condenser as a transmitter, an electro-
scopic instrument as a receiver and a charging battery substantially as described...
5. In a telephone the combination of a condenser acting as a transmitter and
a charging battery for same arranged in the primary circuit of an induction coil
substantially as described.