in telephonic switching apparatus
Year: 1886

page_text: I, ALFRED ROSLING BENNETT of 90* George Street in the City of Edinburgh,
Telegraphic Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention which relates to improvements in telephonic switching apparatus
consists of modifications and developments of the invention described in the Speci-
fication of Letters Patent No. 16,964 of 1884 granted to me.
In lieu of the resistances marked Z¹ Z Z Z in figure 1 of the drawings forming
part of the Specification of Patent No. 16964 aforesaid I employ induction coils of
any efficient type one of the helices of which connect the annunciators X¹ X*X*X*
to the junction point U.
The junction point is then connected directly to the earth.
The other helices of the induction coils are connected all together, either in series
or in parallel arc, and to the receiving and transmitting apparatus.
The new connections are shown in figure 1 of the diagrams accompanying the
present Specification, in which L¹ L L L are four subscribers' lines; J¹ J³ J³ J*
are spring-jacks; X¹ X' X³ X' are annunciators; H H H H are induction coils,
and T, the receiving and transmitting apparatus, the connections of which may be
varied as set forth in the Specification of Patent No. 16,964 aforesaid.
In this figure the helices of the induction coils in connection with T are shown
in parallel arc.
With this modification the operator can either listen continually at T and be
communicated with by the subscribers without being signalled, or the subscribers
can signal by means of X¹ X*X* X' before communicating, the first method bein
suited to constant and the second to intermittent traffic.
Another modification of my invention is shown in figure 2 of the diagrams
accompanying the present Specification, in which L L L L are subscribers lines;
J1 J J J are spring-jacks; X1 X3 X³ X' are annunciators; C¹ C³ C³ C* are
electrical condensers similar to those used in telegraphy; K is a switch and T is
the transmitting and receiving apparatus.
According to this modification J J J J are each joined direct to one plate of
CCCC. X¹ X* X³ X* are connected in branches starting from J¹ Jª J³ J' and
terminating at one side of K. The other side of K is connected directly to the

page_text: earth. The second plates of C C C C are joined to one side of T, of which
the other side is connected directly to the earth. By this modification, when the
traffic is continuous, the switch K is made to disconnect the earth from X¹X*X*X*;
the operator listens continually at T and is spoken to by the subscribers without
being signalled. When the traffic is intermittent the switch K is made to put
X X X X in communication with the earth. The subscriber then signals to the
operator before speaking.
In lieu of the switch K, a resistance, composed preferably of a bobbin of wire,
may be used.
A further modification of my invention consists in employing only one condenser,
the subscribers' lines being joined to one plate and T to the other, the rest of the
connections being as in figure 2 of the annexed diagrams.

page_text: Improvements in Telephonic Switching Apparatus.
I, ALFRED ROSLING BENNETT of 90 George Street in the City of Edinburgh,
Telegraphic 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 which relates to improvements in telephonic switching apparatus
consists of modifications and developments of the invention described in the Speci-
fication of Letters Patent No. 16964 of 1884 granted to me.
In lieu of the resistances marked Z, Z, Z, Z, in figure 1 of the drawings forming
part of the Specification of Patent No. 16964 aforesaid I employ induction coils
of any efficient type one of the helices of each of which connect the annunciators
XXX X' to the junction point U.
The junction point is then connected directly to the earth.
The other helices of the induction coils are connected all together, either in series
or in parallel arc, and to the receiving and transmitting apparatus.
The new connections are shown in figure 1, of the diagrams accompanying the
present Specification, in which L L L L are four subscribers' lines; J₁˚ J³°³ J*
are spring jacks; X1 X3 X*X* are annunciators; H¹ H, H³ H' are induction coils,
and T, the receiving and transmitting apparatus, the connections of which may be
varied as set forth in the Specification of Patent No. 16964 aforesaid.
In this figure the helices of the induction coils in connection with T are shown
in parallel arc.
With this modification the operator can either listen continually at T and be
communicated with by the subscribers without being signalled, or the subscribers
can signal by means of X'X' X*X* before communicating, the first method being
suited to constant and the second to intermittent traffic.
Another modification of my invention is shown in figure 2 of the diagrams
accompanying the present Specification, in which L L L L are subscribers lines;
J1 J J J are spring jacks; X'X' X³ X' are annunciators; C¹ C C C are elec-
trical condensers similar to those used in telegraphy; K is a switch and T is the
transmitting and receiving apparatus.
According to this modification J J J J are each joined direct to one plate of
CCCC. X'X'X' X' are connected in branches starting from J¹ J* J3 J4 and
terminating at one side of K. The other side of K is connecting directly to the
earth. The second plates of C C C C are joined to one side of T, of which the
other side is connected directly to the earth. By this modification when tlie traffic
is continuous, the switch K is made to disconnect the earth from X¹ X'X' X*; the
operator listens continually at T and is spoken to by the subscribers without being
signalled. When the traffic is intermittent the switch K is made to put XX*X*X*
in communication with the earth. The subscriber then signals to the operator
before speaking.
Instead of one switch K, as shown in figure 2, it is preferable to have as many
switches as there are subscribers' lines, the lever of the first switch being connected

page_text: to ; the lever of the second switch to X', etc; etc; earth being joined to the
opposite sides of all the switches. These switches may be readily combined so
that one movement will suffice to charge them all from the "continuous" to the
"intermittent " positions or vice versa.
In lieu of the switch or switches, K, a resistance, or resistances, composed prefer-
ably of a bobbin, or bobbins, of wire may be used.
A further modification of my invention consists in employing only one condenser,
the subscribers' lines being joined to one plate and T to the other, the rest of the
connections being as in figure 2 of the annexed diagrams.
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. As a development of the invention described under Letters Patent No. 16964
of 1884 the employment in telephonic switch apparatus of induction coils for the
purpose set forth.
2. As a development of the invention described under Letters Patent No. 16964
of 1884 the employment of an electrical condenser or condensers for the purpose
set forth.
3. In telephonic switching apparatus the arrangement of induction coils and
connections substantially as described with reference to figure 1 of the annexed
drawings.
4. In telephonic switching apparatus the arrangements of an electrical condenser
or condensers and connections substantially as described with reference to figure 2
of the annexed drawings.
1000