Year: 1889

page_text: I, ALFRED ROSLING BENNETT of 8 Duddingston Park, Portobello, in the County
of Mid-Lothian, Telegraph 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 consists of improvements on and of modifications and developments
of the Invention described in my application for Letters Patent No. 2748 dated
16th February 1889, and the general objects of my invention are the same as are
therein set forth.
The more immediate objects of my invention are to dispense with one of the plugs
or pegs employed in connecting two subscribers' lines together, and to dispense with
the special wire uniting the several blocks common to a subscriber's line for the
purpose of enabling an operator to discover whether that line has been put into use
by any other operator.
Except where otherwise stated, the mode of connecting each subscriber's line to its
several blocks is precisely the same as set forth in the Specification and clearly
shewn in Figures 1, 4, 11 and 14 of the drawings under the aforesaid application.
The first improvement is shewn at Fig. 1 where B1, B2, B³, are the blocks
Each block
connected to line and B4, B5, B6, are the blocks, connected to line 2.
consists of a piece of metal with a hole, preferably circular, made in it suitable for
the reception of an appropriately shaped plug or peg.
The plugs or pegs used for connecting two of the blocks together are shewn at
Fig. 2 connected by a flexible conductor, in the circuit of which is included a source
of electricity, preferably a voltaic battery.
The pegs consist of pieces of metal shaped to fit tightly into the holes in the
blocks so as to afford good electrical contact therewith.
It will be evident that if one peg is inserted in any one of the blocks connected to
line 1 and the other peg in any one of the blocks connected to line 2 a current from
the source of electricity will flow over the two lines.
And that if an operator stationed at any of the blocks wishes to ascertain whether
the line is engaged or not, and touches the block nearest him with a metallic pin
=

page_text: connected to earth through a volta meter, or any other instrument capable of showing
by sound or movement etc. presence of electricity [such an arrangement is shewn in
fig. 7 of the drawings aforesaid] he will be able to so ascertain, for if the line is
engaged a portion of current from the source of electricity in the circuit of the
flexible conductor will flow through the metallic pin and voltameter or other
instrument where its presence will be evident. If the line is not engaged no current
will be perceptible.
In figures 3 and 4 are shewn other modifications of my invention, which modifications
refer more especially to the plans shewn in Figure 11 and 14 of the drawings under
my said previous application.
The blocks B', B2, B3, and B4, B5, 13 are connected to their respective lines as
herein before described. According to the modification shewn in Fig. 3 each block is
connected to earth through an electro magnet M of high magnetic inertia or self-
induction, one or all of which electro-magnets may be made to actuate one of the
many known devices for indicating the passage through the coils of the electro-
magnet of a current of electricity suitable for calling the attention of the operator
when the subscriber wishes to begin or terminate a correspondence. According to
the modification shewn in Fig. 4 only one such electro magnet M is used, which is
shewn connected to earth through the last block. In practice it may be connected
to the first or any of the blocks.
It is evident that if such a pair of pegs with a source of electricity in the circuit of
the flexible conductor as is shewn in Fig. 2 be used for connecting the blocks of
Figs. 3 and 4 together, an operator will be able to discover whether the line is or is
not engaged by the use of the same device as is described in connection with the
modification shewn in Fig. 1.
In figure 5 is illustrated another modification of my invention. The blocks B1, B2, B³,
and B, B, B are arranged as previously described and each of the blocks of each
line is connected permanently by means of a flexible conductor in the circuit of which
is a source of electricity to a peg such as the peg shewn in Fig. 2.
It is evident that so long as none of these pegs is inserted in a block one pole of the
But if
source of electricity will be insulated and consequently no current will flow.
any of the pegs connected with the blocks of Line 1 or Line 2 be inserted in any one
of the blocks connected to any other line. it is clear that a current will circulate, the
presence of which may be detected by the use of the device described in connection
with Figure 1.
The addition to the modifications shown in Figures 3 and 4 of a pog connected
permanently to each block of each line by a flexible conductor in the circuit of which
is a source of electricity will enable the pair of pegs as shewn in Figure 2 to be
dispensed with. The connecting of the blocks of any line to the blocks of any other
line will be managed with one peg and the mode of discovering whether or not the
line is engaged will be the same as in the modification shown in Figure 5.
An adaptation of my invention to the system of switching generally known as the
Multiple Switch Board of the Western Electric Company is shown in Figure 6.
According to that system each block connected to a subscriber's line is in two parts
which are normally in electrical contact with each other but are forced apart and
insulated from each other by the insertion of the form of peg employed with that
system. The subscriber's line is connected to the top contact of the first block, from
the bottom contact of the first to the top contact of the second, and so on through all
the blocks, the bottom contact of the last block being connected to the earth. At any
point of the circuit an indicator of any pattern efficient for signalling is inserted. The
adaptation of my invention to this system consists in the use of an electro-magnet of
high magnetic inertia or self-induction. in lieu of the indicator aforesaid and of a pair
of pegs connected by a flexible conductor in the circuit of which is a source of
electricity, the said pegs being constructed so that when inserted in a block the two
parts of the block shall not be insulated from each other but shall be kept in electrical
contact through the body of the peg. The adaptation also consists in modifying the
pattern of blocks, so that the top and bottom portions may be put in contact by the

page_text: insertion of a metallic peg. There are many methods well known to telephone
engineers of accomplishing this and which I do not claim as any part of this
Invention. One such method is shown at Figare 7 where B is a metallic block
normally retained against another metallic block, b, by the spring s. The blocks
are grooved for the purpose of receiving such a peg as is shown in Figure 2.
On the insertion of a pair of such pegs in any of the blocks connected to any
two subscriber's lines, it is evident that a current from the source of electricity will
circulate through both lines and all the blocks where its presence can be detected
by the device described in connection with Figure 1.
The addition to this adaptation of a peg connected permanently to each block of
each line by a flexible conductor in the circuit of which is a source of electricity
will enable the pair of pegs as shown in Figure 2 to be dispensed with. The
connecting of any of the blocks of Line 1 to any of those of Line 2 will be
managed with one peg and the mode of detecting whether the line is in use
or not will be the same as in the modification shown in Figure 5. The electro-
magnet M (Figure 6) is shown as connected to earth from the last block but in
practice it may be connected from the first or any of the blocks.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is: -
In telephonic switching apparatus the provision of devices substantially as herein-
before described for making connections between subscribers' lines and indicating
when subscribers are engaged.
IT......
M 1000
CRUIKSHANK & FAIRWEATHER,
62, Saint Vincent Street, Glasgow,
Agents..