IMPROVEMENTS IN TELEPHONIC APPARATUS
Year: 1883

page_text: LETTERS PATENT to Alfred Rosling Bennett of 134 Douglas Street Glasgow
in the County of Lanark Telegraphic Engineer for an Invention of
"IMPROVEMENTS IN TELEPHONIC APPARATUS"
PROVISIONAL SPECIFICATION left by the said Alfred Rosling Bennett at
the Office of the Commissioners of Patents on the 1st March 1883.
ALFRED ROSLING BENNETT, of 134 Douglas Street, Glasgow, in the County of
Lanark, Telegraphic Engineer, "IMPROVEMENTS IN TELEPHONIC APPARATUS,"
"
The first part of my Invention has reference to the translation of telephonic
impulses between ordinary single wires joined to earth at their extremities, and
double wires or metallic circuits of which the earth forms no part, and is a
development of the Invention described in the Specification of my Patent N° 4428
of 1881.
When induction coils are used for this purpose in the manner fully set forth
and described in the Specification of my Patent N° 4428 of 1881, I find it
advantageous to wind the coils with a third or tertiary wire, superimposed upon
the primary and secondary wires, and to join the ends of this tertiary wire, either
directly together, or through a wire or conductor possessing electrical resistance.
Or they may be joined to earth either directly or through resistance.
Instead of being wound upon a soft iron core as set forth in the Specification of
the aforesaid Patent, N° 4,428 of 1881, the primary and secondary wires, upon
which may be superimposed a tertiary wire, may be wound upon one end or pole
of a steel permanent magnet, or upon one end or pole of an electro-magnet.
Another method of translating telephonic impulses between single wires and
metallic circuits, consists of a combination of a receiving telephone, which may be
either of the Bell or of the Edison type, with a Blake transmitter, or any other

page_text: transmitter to which the sound waves which it transforms into electrical impulses,
are conveyed through the medium of a disc or diaphragm. To the vibrating disc
of such a receiving telephone, I attach directly the mechanism of the transmitter,
in such a manner that the vibrations of the receiving disc set up by the passage of
electrical impulses through the coils of the receiving telephone are imparted to the
transmitter and by it re-converted into electrical impulses. The receiving telephone
being in circuit with one wire, and the transmitter with a second, the impulses will
clearly be translated or communicated from the first to the second wire. For
translation in both directions each wire must be furnished with a receiving
telephone, having attached to its disc a transmitter which is in circuit with the
other.
Another plan of accomplishing the same object consists in the use of electrical
condensers having three, four, or more plates instead of the two with which such
condensers have been invariably furnished. By one modification of this plan, the
end of the single wire and earth are connected to one pair of plates, and the ends
of the metallic circuit to another pair.
Any of these methods are adapted for translation between two single wires, or
between two metallic circuits, as well as between a single wire and a metallic
circuit.
The second part of my Invention relates to the transmission of telephonic
impulses, over long lengths of wire. As is well known, the effects of the
phenomenon termed electro-static induction has heretofore limited the successful
application of the telephone to lengths of about 200 miles of aërial wire, and to
much shorter lengths of buried or submerged wire.
To overcome the deleterious effects of electro-static induction, I divide the long
line over which it is desired to transmit telephonic impulses into convenient
sections, all of which must be short enough to be spoken over with ease by means
of ordinary instruments.
C..
At the termination of each section, I place translating apparatus which may be
of any of the types described in the Specification of my Patent N° 4,428 of 1881,
and in the present Provisional Specification, or of any other efficient type. The
long line being divided into sections having no direct or metallic connection with
each other, the total amount of retardation or interference due to electro-static
induction, on the whole will be only that proper to the longest section.
The third part of my Invention relates to the destruction or modification of the
effects upon a single telephonic wire of electro-dynamic induction from neighbouring
or parallel telegraphic or telephonic wires.
to
The destruction or modification of such effects may be accomplished, according
my Invention, in three ways:-
Firstly, by the insertion of ordinary induction coils in circuit with the line at
each end thereof, such induction coils to have primary wires of very small resistance,
and secondary wires of larger resistance. The coils may have iron cores, or no
cores at all. The primary wires of the coils should preferably be in circuit with
the line, while the receiving telephones are attached by their connecting wires to
the secondaries, but this arrangement may be reversed.
Secondly, by the insertion in circuit with the line at each end thereof of
electrical two-plate condensers of the ordinary construction of such small capacity
that the disturbing effects in the telephones, of the electro-dynamic induction from
other lines, are either entirely destroyed or greatly modified by being forced to pass
through them.
Thirdly, by the use of shunts or derived circuits at both ends of the line,
arranged so as to divert a portion of the received currents to earth before reaching
the receiving telephones, or to prevent a portion of the received currents passing
through the telephone by means of a loop of wire possessing some electrical
resistance between its terminals.
The effect of each of these devices is to diminish. the strength both of the

page_text: telephonic impulses proper to the line itself and of the inductive disturbances due
to the proximity of other telegraphic or telephonic wires.
The decrease in strength of the telephonic impulses I find can be easily
compensated for by the use of two, three, four, or more battery cells, which cells
must be joined for tension or quantity, according to the character of the transmitter
with which they are employed.
The degree of immunity from disturbing inductive effects obtained can be
regulated with considerable nicety, by varying the resistances of the primary and
secondary wires of the induction coils, and the size and character of their cores,
according to the first plan, by varying the size of the condenser plates according to
the second plan; and by varying the resistances of the shunts or derived circuits
according to the third plan.
+

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Rosling Bennett in the Great Seal Patent Office on the
'30th August 1883.
い
L.
ALFRED ROSLING BENNETT, of 134 Douglas Street, Glasgow, in the County
of Lanark, Telegraphic Engineer, "IMPROVEMENTS IN TELEPHONIC APPARATUS'
.1.
i.
The first part of my Invention has reference to the translation of telephonic
impulses between ordinary single wires joined to earth at their extremities, aud
double wires or metallic circuits of which the earth forms no part, and is a develop-
ment of the Invention described in the Specification of my Patent No 4428
of 1881.
When induction coils are used for this purpose in the manner fully set forth and
described in the Specification of my Patent N° 4428 of 1881, I find it advantageous
to wind the coils with a third or tertiary wire, superimposed upon the primary and
secondary wires, and to join the ends of this tertiary wire, either directly together,
or through a wire or conductor possessing electrical resistance. Or they may be
joined to earth either directly or through resistance.
Instead of being wound upon a soft iron core, as set forth in the Specification of
the aforesaid Patent No 4428 of 1881, the primary and secondary wires, upon
which may be superimposed a tertiary wire, may be wound upon one end or pole
of a steel permanent magnet, or upon one end or pole of an electro-magnet.
Another method of translating telephonic impulses between single wires and
metallic circuits, consists of a combination of a receiving telephone, which may be
either of the Bell or of the Edison type, with a Blake transmitter, or any other
transmitter to which the sound waves which it transforms into electrical impulses
are conveyed through the medium of a disc or diaphragm. To the vibrating disc
of such a receiving telephone, I attach directly the mechanism of the transmitter,
in such a manner that the vibrations of the receiving disc set up by the passage of
electrical impulses through the coils of the receiving telephone are imparted to the
transmitter, and by it reconverted into electrical impulses. The receiving telephone
being in circuit with one wire, and the transmitter with a second, the impulses will
clearly be translated or communicated from the first to the second wire. For
translation in both directions each wire must be furnished with a receiving
telephone, having attached to its disc a transmitter which is in circuit with the
other.
Another plan of accomplishing the same object consists in the use of electrical
condensers, having three, four, or more plates instead of the two with which such
condensers have been invariably furnished. By one modification of this plan, the
end of the single wire and earth are connected to one pair of plates, and the ends of
the metallic circuit to another pair.
Any of these methods are adapted for translation between two single wires, or
between two metallic circuits, as well as between a single wire and a metallic
circuit.
The second part of my Invention relates to the transmission of telephonic
impulses over long lengths of wire. As is well known, the effects of the
phenomenon termed electro-static induction has heretofore limited the successful
application of the telephone to lengths of about 200 miles of aërial wire, and to
much shorter lengths of buried or submerged wire.
To overcome the deleterious effects of electro-static induction, I divide the long
line over which it is desired to transmit telephonic impulses into convenient
sections, all of which must be short enough to be spoken over with ease by means
of ordinary instruments,

page_text: At the termination of each section I place translating apparatus which may be
of any of the types described in the Specification of my Patent N° 4428 of 1881,
and in the present Complete Specification, or of any other efficient type. The long
line being divided into sections having no direct or metallic connection with each
other, the total amount of retardation or interference due to electro-static induction,
on the whole will be only that proper to the longest section.
The third part of my Invention relates to the destruction or modification of the
effects upon a single telephonic wire of electro-dynamic induction from neighbouring
or parallel telegraphic or telephonic wires. The destruction or modification of such
effects may be accomplished, according to my Invention, in three ways:-
Firstly, by the insertion of ordinary induction coils in circuit with the line at
each end thereof, such induction coils to have primary wires of very small resist-
ance, and secondary wires of larger resistance. The coils may have iron cores, or
no cores at all. The primary wires of the coils should preferably be in circuit with
the line, while the receiving telephones are attached by their connecting wires to
the secondaries, but this arrangement may be reversed.
Secondly, by the insertion in circuit with the line at each end thereof of electrical
two-plate condensers of the ordinary construction of such small capacity that the
disturbing effects in the telephones, of the electro-dynamic induction from other
lines, are either entirely destroyed or greatly modified by being forced to pass
through them.
Thirdly, by the use of shunts or derived circuits at both ends of the line,
arranged so as to divert a portion of the received currents to earth before reaching
the receiving telephones, or to prevent a portion of the received currents passing
through the telephone by means of a loop of wire possessing some electrical resist-
ance between its terminals.
The effect of each of these devices is to diminish the strength both of the
telephonic impulses proper to the line itself and of the inductive disturbances due
to the proximity of other telegraphic or telephonic wires.
The decrease in strength of the telephonic impulses I find can be easily compen-
sated for by the use of two, three, four, or more battery cells, which cells must be
joined for tension or quantity, according to the character of the transmitter with
which they are employed.
The degree of immunity from disturbing inductive effects obtained can be
regulated with considerable nicety, by varying the resistances of the primary and
secondary wires of the induction coils, and the size and character of their cores
according to the first plan; by varying the size of the condenser plates according to
the second plan, and by varying the resistances of the shunts or derived circuits
according to the third plan.
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, The various methods and improved arrangements of apparatus for
translating and transmitting telephonic impulses, substantially as herein described.
In Witness Whereof, I, the said Alfred Rosling Bennett, have hereunto set my
hand and seal, this Twenty-eighth day of August, in the year of our Lord
One thousand, eight hundred and eighty-three.
Witness
WALLACE FAIRWEATHER C.E. Fel. Inst. P.A.
96 Buchanan Street
Glasgow.
A. R. BENNETT. (L.S.)