Improvements in Multiple Switchboard Apparatus for Telephonic Installations with Metallic Circuits of the system Berthon."
Year: 1892

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by SOCIÉTÉ GÉNÉRALE DES TÉLÉPHONES (Resedux
Téléphoniques et Constructions electriques), of 41, Rue Caumartin, Paris,
France, Manufacturers.]
Improvements in Multiple Switchboard Apparatus for Telephonic
Installations with Metallic Circuits of the system Berthon."
66
I, CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane,
in the County of London, Chartered Patent Agent, 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 :-
This invention relates to improved constructions and arrangements of the plugs
and spring jacks for multiple switchboards of the system "Berthon" of telephonic
apparatus with metallic circuits, which I will describe with reference to the
accompanying drawings. The plug shewn in end view at Fig. 1, in longitudinal
sections on lines A B and C D, at Figs. 2, and 3 and in cross section at E F
at Fig. 4, is constructed of two pieces of brass or other metal a b, a¹ b¹ imbedded
along part of their length in a block c d of insulating material known as "ivorine"
the metal pieces being formed with notches or bulges e e' into which the ivorine.
penetrates so as to be effectually secured thereto.
Outside the block c d the two pieces of metal a b, a¹ b', are separated from each
other by a thickness of ivorine f which is held in grooves g in the metal
pieces a b, a' b¹.
The inner ends of the strips of metal have longitudinal holes h bored in them
into which pass the metal rods that are secured to the ends of the wires of the
flexible conducting cable i.
For preventing all contact between the two metal rods, the block c d of ivorine
is extended as a partition j between them.
In the insulating block c d are also imbedded two screw nuts k k¹ into which are
screwed the screws that secure the sheath 1 m of ivorine that encloses exactly the
above described parts.
The closed rear end m of the sheath has a hole formed in it through which
passes the flexible conducting cord i.
A small copper tube n or ring is clamped on the worm covering of the flexible
conductor within the rear end of the sheathing, so as to constitute a collar that
prevents the conductor from being drawn out of the sheathing.
The block of ivorine is moulded in a divided steel mould, the interior of which
has the exact configuration of the block to be produced. This mould being heated
to the required degree, the above mentioned pieces of metal which are to be
imbedded in the block namely a, b, a b', and k are first introduced into the
mould, and the remaining spaces are then filled in with ivorine and the whole is
then subjected to strong pressure in the mould. After cooling, the formed mass is
removed from the mould.
The flexible conducting cable i contains two conductors each of which is formed
of a coiled brass wire n the end of the coil being screwed on to a threaded copper
rod a Fig. 5, and is then covered over by a winding of metal thread for diminishing
the resistance of the joint, and this is then covered by a silk or cotton winding or
braiding o Fig. 5 and over this is fixed a thin metal tube c Fig. 6 which covers both
the end d' of the metal rod a and that of the said windings or braidings, to which
it is secured by indentations e", ell. Fig. 6 shews one end of the flexible con-
ducting cable, the metal rods, of which are secured in the holes of the plug as
before described, and, the metal covering at the other end of the flexible con-
ductor shewn at Figs. 7 and 8, which is constructed in the same manner without
.

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page_text: The contact with the plug F1, will then cause a sound in the telephone T¹.
The reduced size of the above described spring jacks allow of the construction
of switchboards of great capacity which can be served by the telephone attendants
when seated.
Figs. 13 and 14 shew the complete installation of a switchboard for 6000
circuits.
The call signals of the subscribers are at the upper part at Z; and just below
these, the signals for the end of speech, Y; then come the local spring jacks
at X, and the general spring jacks at U. The table V carries the plugs y y', the
lever commutators λ, and the calling keys u. The return cables of the call
signals are placed at K. The last call signal is placed at 1.86 metres_above_the
ground line, this being a height that can readily be reached by an official seated on
a high seat.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The herein described construction and arrangement of plugs for the spring
jacks of telephone apparatus.
2. The herein described construction and arrangement of the flexible conducting
cables and their attachment devices.
3. The herein described construction and arrangement of the rows of spring
jacks.
4. The combination of the devices referred to in the preceding claims and their
application as described to multiple commutators of telephonic apparatus, substan-
tially as described.
Dated this 14th day of Mo 1900
ABEL IMRAY,
Agents for the Applicant.