Year: 1894

page_text: Date of Application, 30th Apr., 1894
Complete Specification Left, 29th Jan., 1895-Accepted, 24th May, 1895
I EMILE ANDREOLI Journalist of 18 Somerleyton Road Brixton London S.W.
in the County of Surrey do hereby declare the nature of this invention to be as
follows:-
The object of this invention is to provide efficient means whereby the telephonic
communication between a very great number of subscribers may be satisfactorily
effectuated.
To this end we make use in our invention of a peculiar manner of distribution
and association of the ordinary elements of multiple double cord switch
boards, and this mode of association is based upon the arithmetical principle of
combination.
corre-
In this system the employment of arithmetical combination is realized in such
a way that the totality of subscribers' lines are divided into a number n of sections,
n (n-1).
number large enough to make the number of binary combinations
spond with that of multiple tables necessitated by the usual division of work in
central telephone exchanges.
2
The subscribers of every one of said sections have general contact devices
(multiple jacks or plugging holes) on (n-1) binary combination boards and usually
none on the other boards; every subscriber possesses also at some place of the
exchange a call receiving device (subscriber's annunciation drop).
Each combination board is provided with multiple jacks belonging to two
different sections and is more especially charged to realize the possible connection
between any subscriber's line of one section and anyone of all subscribers' lines
contained in the second section of the said board.
For the establishment of most of the conversations orders are transmitted
telephonically between two or more of the operators.
Suppose, for example, the organization of a central telephone exchange designed
for 60,000 subscriber lines. These lines are divided into 25 sections (number of
sections n-25) each of which is distinguished by a letter of the alphabet.
The number of combination boards will be 300, as given by the number of binary
25
combinations of those 25 sections (300 24 n (n-1)) each of these boards
=
2
-
2
being distinguisbed by the association of the two letters ascribed to the two combined
sections, such as A H, E V, ER, HS, etc.
Each section presents itself on 24 combination boards (24 = n-1) and, as already
stated, is distinguished from others by a letter of the alphabet, which letter may
conveniently be accompanied by the number expressing its order of parity in the
alphabet, such as A, B, C, D,.
X 24 Z95
The number of lines of each section is (for convenience of division) made a
decimal multiple of the number (n-1) of combination boards contained in each
section; taking our actual example, this number of lives is 2,400 for (2400 = 24 100).

page_text: In each section the numeration goes on by hundreds of lines from 1 to 25 (1 to n).
and one series of hundred lines, the one corresponding by its number to the letter of
the section, suppressed.
The call of each subscriber's line is received and made apparent by an individual
device (annunciator drop) which may be located anywhere within the exchange.
The system above described works on the following general lines.
A call comes in from any line. The subscriber announces what communication
he wants.
If the call arrives at a combination board, and if the line wanted is
located in one of the two combined sections of that board, the operator may directly
connect the two lines together as is usually done with multiple double cord switch
boards.
In all other cases, on the contrary, the operator, speaking through a local
telephonic intercommunication line, transmits the order which he has received to
the operator having charge of that combination board which contains together the
section of the calling subscriber and the section of the demanded one. The
subscriber may be enabled to hear the transmission of the demand after the reception
of which the operation of connecting the two subscribers' lines occupies solely the
Fecond operator.
Two lines, as for example one belonging to the section H, and the other one to
the section S, are thus finally connected by the usual connecting cord making
communication between the jacks of said two lines located on sections H and S of
combination board H S. It may be noted that the telephonic transmission of
orders between operators is only a transient operation and does not introduce nor
occupy any trunk line during the conversation.
In its practical applications this telephone exchange may utilize the apparatus
of any of the different double cord multiple switchboards in use in Europe and
America.
Dated this 30th day of Anril 1894
EMILE ANDREOLI.
EMILE ANDREOLI, Journalist of 18 Somerleyton Road, Brixton, S. W. London,
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 :-
The object of the present invention is a new switch arrangement for central
telephone exchanges, particularly for such exchanges where there are a great
number of subscribers. The mode of connecting up the lines results from a new
application of the arithmetical principle of combinations, in subdividing and
associating the usual constituent parts.of multiple double-cord switches.
A feature of this invention is the use of an order transmitted locally in the
exchange.
2
The use of combinations includes in this system the subdivision of the subscribers
into a number n of sections, sufficiently large for the number
n (n-1)
of binary
combinations of these sections among themselves, to correspond to the usual division
of the work in the central telephone exchanges, according to the series of general
jacks and to the number of operators necessary for carrying out the work.
The subscribers of any one section have multiple "jacks or "plugging holes"
in (n-1) combination boards and usually none on the other boards, and in the
exchange, a subscriber's "annunciator-drop." In addition, the subscribers in each
section, have a jack for interurban communication.
"

page_text: Each combination board is provided with " multiple jacks" belonging to two
different sections and is more specially devoted to establish the possible connection
between any subscriber's line of one section and any other subscriber's line in the
second section of the said board.
The detailed description of the whole system will clearly explain the short
preliminary introduction, but which is necessary in order to show the general idea
of the system, independently of the several methods of application.
Fig. 1 shows the detailed arrangement of a central telephone exchange with
multiple combination boards and also numbers and diagrains. It represents a
central telephone exchange for 60000 town subscribers, capable of being put in
connection with circuits from other towns leading to the same exchange, who
necessarily, may also be put in connection with interurban circuits, forming a
special section of the same exchange.
.
The triangular diagram of Fig. 1, includes all the combination boards by means
of which the connections between town subscribers may he realized, and the upper
Z W contains
horizontal row of combination boards, denoted A W, BW,
the auxiliary combination boards which may be added for enabling the same
exchange to put the town subscribers' lines in connection with interurban lines.
These interurban lines form the group or section denoted W and repeated on all
the combination boards of the upper horizontal row.
Fig. 1 does not show all the lines running through the exchange; it only shows
as examples the run of two subscribers' lines as will be explained later on.
But, it
should be understood that all the 60000 single or double lines of the 60000 sub-
scribers come into the exchange, where they are divided into 25 different sections
(the number of sections n = 25) each denoted by a letter of the alphabet. The
number of town combination boards is 300, the number. of binary combinations
¸n (n-1) 25 × 24
300 and each one is distinguished by the two letters of
being"
2
=
2.
-
the combined sections, e.g.: A V, E V, ER, H S.
In Fig. 1, the 300 combination boards A B
Y Z, each one formed of two
of these different sections of town subscribers are indicated.
Fig. 2 exemplifies the general arrangement of one of these combination
boards HS, before which sit the operators with the necessary devices for
establishing connections.
In order to ensure the connection of the inter urban circuits with the town
circuits, there is a special combination board for each of the 25 sections combined
with the supplementary section W, formed of the inter urban lines, considered as
subscribers.
Each section is repeated on 24 town combination boards (24 = [n-1] town-boards
and on an inter-urban board; each section is distinguished by a letter of the
alphabet which letter may be accompanied by the number denoting its order of
This method of distinction is
parity in the alphabet, such as A, B, C, D, etc.
useful for allotting reference numbers to the subscribers in each section.
The number of lines in each section is generally, for convenience of classification,
a decimal multiple of the number (n-1) of combination boards in each section; in
the example above, it is 2400 i.e. 24 x 102.
In each section, the numeration goes by hundred of lives, and runs from 1 to n
(1 to 25), eliminating the hundred whose number corresponds by order of parity
with the letter of that section-; thus, the 2400 lines of the section H bear the
number 100 to 799 and 900 to 2599; the hundred whose name would be 8 does not
exist in this section, the letter H being the eighth in the alphabet.
According to this convention, no subscriber's circuit bears any figure below 100;
thus the preceding reference numbers exist on the lower part of Fig. 2, where they
indicate the horizontal strips of multiple-jacks.
1.
It can be seen that each subscriber's line having multiple-jacks for town
connections in the (n-1) combination boards of his section, can be put into com-
munication at each of these with the 2400 lines of another combined section; thus,

page_text: the (n-1) boards with 57600 subscribers' lines (57600 = 24 × 2400); the remaining
2399 possible connections with the subscribers of his own section, can be made at
any of the boards of this section.
To ensure the proper working of the system thus described, the operators at
the exchange must be advised of the connection required this result is obtained
by the transmission of an order telephonically between operators stationed at the
combination boards of each section.
Every subscriber calls up the exchange by an annunciator-drop, which can be
placed anywhere in the exchange without interfering with the general working of
the system. However, in the example shown, the annunciator drops of the town
circuits are supposed to be distributed in two hundreds accompanying the binary
combination boards, and it is the order of parity of the letter of the section which
determines that of the hundred annunciator-drops of the other section belonging to
that board; thus, Fig. 2, in the combination board H, S₁,, the name of the hundred
annunciators accompanying the letter H is 19, 1900 to 1999, corresponding to the
order of parity of the letter S of the combined section. On the board S, the
annunciator drops bear the figure 800 to 899, the name of the hundred being 8.
In the same Fig. 2, the numbers 1-10, 11-20 refer to the usual clearing-out drops
belonging to the operators' apparatus set.
Fig. 1 shows the necessary interdependence of the boards of each section (due
to the passage of the wires) as an example, one sees Fig. 1, the course through the
exchange of two subscribers' lines, belonging to two different sections, the one
jj of section H, the other one l'z of section S. Each line possesses in each
half-board of its section a multiple-jack shown as a black dot on the diagram.
The combination board HS is the one having the multiple-jacks of the two
different sections H and S.
The line of section H is supposed having a reference number belonging to
the hundred whose name is 22, and its annunciator is therefore situated on com-
bination board HV (annunciator represented on diagram by a square) V being
the 22nd letter, of the alphabet. The line of section S has its annunciator on
combination board R S. It does not follow however, that the triangular disposition
of the combination boards, as shown, is essential in fitting up an exchange.
Fig. 3 shows for example, the arrangement of the boards in a straight line as is
usually done; it is the result of putting in a single row one after the other, the
several successive vertical rows of boards, shown in the general arrangement in
Fig. 1 A B C D E etc. are the strings of wires which connect up the multiple jacks
of the subscribers of the correspondingly named sections.
According to the way in which the installation is fitted up, the relative positions
of the boards may help to systematically suppress other boards whose work can be
done by the adjoining ones.
Thus, Fig. 4, shows a reproduction of the original triangular diagram with these
suppressions, which the adoption of the linear arrangement of boards allows of; the
boards to be suppressed, are shown cut or radiated by diagonal lines.
Fig. 5 shows the rearrangement of the remaining boards, in order that the
continuous order of the vertical columus still corresponds to that of the boards in
their linear arrangement in the installation, and Fig. 6 represents the linear row
arrangement with the run of the strings or cables of wires.
The utilisation of the relative positions of vicinity by means of systematic
suppressions as above, can according to the special conditions of each application
of the system, lead to various but analogous uses, according to the requirements of
the case, which telephone people will understand.
Without going into all the details of installation; the method of working the
system is as follows:
A subscriber's call on the exchange is made known to the operator by the fall of
the-subscriber's annunciator drop; the subscriber makes known, by means of the
telephone the connection he requires; should the call arrive at a combination
board as in Fig. 2, and should the subscriber, wanted belong, to, one of the two.
24.

page_text: combined sections of that board, the operator can connect the two lines, directly
as is usually done with multiple double-cord switches. In every other case, the
operator transmits verbally, by means of a local intercommunication telephone
line the order which he has received to the operator stationed at the combination
board of the two sections to which the two subscribers in question belong. The
calling-subscriber hears the verbal transmission of the local order for the connection
required in the exchange, the object of which is to substitute the second operator
for the first, and who alone has now to connect up the two subscribers. The
connecting up of two subscribers, one belonging to the section H and the other to
the section S is brought about, according to the principle of the system, by means
of the combination board H S, the only one having the jacks of these two sections
together, and which can connect them up directly, in the usual way, as with
multiple double cord switches.
The local orders alluded to before between operators of different combination
boards of the same section are transmitted by special telephonic local circuits.
As an indication of the use of such service lines, the diagram Fig. 1 shows for
section M, by 2, the run of such a line. In the lower part of Fig. 2, the
rows A B C
show the strips of jacks of these local service lines. G are devices
by means of which the operator may be called up by the other operators of the
same section.
This description refers generally to the various modes of installation of electrical
intercommunication of the lines, according to the way of putting up the circuits
wherever the system is to be applied.
While particularly claiming the general applications of the system, we specify
that it can be applied, with suitable alterations-by making use of the ordinary
multiple double cord switches, particularly those of the Western Electric Co. for
"two-wire" or mixed circuits, those of the German system known as the
Orsterreich system, those of the Post Office and of the Western Electric Co.
used for the "branching system."
I will now fully describe the application of the system of telephone exchanges
with multiple combination boards, and utilizing the jacks and appliances as used in
the branching system.
Fig. 7 shows the stations of two subscribers with the double wires from each
passing through the boards of their respective sections, for each line, are shown
several jacks denoted by the letters of the combination boards on which they are
located (S. . . SH, ST
SR.. Sz; Hw..
H, H... Hx... Hz) as
already shown in Fig. 1. The same letters l, refer to the wires of the line of
the calling subscriber, whose course through the exchange is also shown in Fig. 1.
The letters j¹ are in a similar manner attributed to the called subscriber's line.
Fig. 7 gives also the apparatuses and connections of the operator who receives
directly the calling subscriber's signal (first answering operator's set SR). In a
like manner, the apparatuses of the second operator (connecting operator's set SB)
are shown in the middle of Fig. 7; the local lines (r) which are used in the
intercommunication between the operators at the boards SB & Sд are shown.
Fig. 1 also shows the course followed by the two subscribers' lines in the
exchange, one from the section S and the other from the section H, together with
the boards where these lines are joined to jacks; also the combination board S H,
which being that common to the two sections, is that used for putting them into
direct communication. The inter communication between the operators at the
board of any one section is carried out for each half board by a local telephonic
line (2) provided with a local annunciator G, (Fig. 7) with listening key V,
battery p and contact to earth e, and having a local jack at each town board of the
section S and at the interurban board S W.
"
In Fig. 7, the apparatuses and connections represented are situated in different
regions. So, for example, shall it be understood that the "calling subscriber's set
includes the different devices placed at this subscriber's station. From there the
line goes to the exchange where it first reaches a jack located on halfboard Sw'of

page_text: combination board S W. Then the line runs through all the halfboards SA, SB,
Sc,....SH. . Sz of the combination boards A°S, B S, CS, . . . . H S...
SZ belonging to the same section S, and reaches on each board, a jack, so that the
different general jacks represented in Fig. 7 are placed on different boards of the
exchange (to simplify the diagram, a great number of jacks have been omitted,
but their situation may be seen in Fig. 1). Similar representations have been
adopted for the called subscriber's line shown on the right side of Fig. 7, as also
for the local lines r¹.
Further on,
it is to be understood that the first operator (SR) is stationed before
the halfboard SR of combination board R S, and that the second operator (SЯ) is
stationed before the half-board S₁ of combination board H S.
In Fig. 7, similar objects are denoted by the same letters; thus telephone
receivers are denoted by the letter t or t', they being distinguished by the fact that
one belongs to the first operator's set, a second one to the second operator's set and
a third one to a subscriber's set. The same letter e denotes earth connections, all
these connections going to a common conductor, earth or wire.
In Fig. 7:
I is the secondary circuit of an induction coil and implies the existence of
the ordinary primary circuit with primary battery and microphone, .e. the local
organs of transmission which are not shown so as to avoid too complicated diagrams.
tt are the telephone receivers. b is a suspension hook which acts as an automatic
circuit. Its position as well as that of the listening and calling keys only shown
by the switch springs and that of the plugs and jack contacts depends on the
particulars given of the connections required.
e is a contact to earth or to a common wire.
C is a condenser which breaks the electric circuit without interfering with the
telephonic cominunication.
P is a battery used for calling up;
.
p is a local battery for working a line or for automatically raising an
annunciator drop;
S is a bell or calling device.
G is a galvanoscope or annunciating device.
The method of working can be followed from Figs. 1 and 7.
Taking Fig. 1, we see that a call coming in from subscriber's line z of
section S will be signaled by the annunciator located on halfboard SR of section RS.
If the calling subscriber desires, for instance to be put in communication with a
subscriber's line jj₁ = of section H, the operator stationed at halfboard SR transmits
telephonically, by the local service line passing through all the boards of section S
(just like local linerz shown as an example passes through all the boards of
section M) the demand of the calling subscriber to the operator stationed at half-
board SE of combination board HS, which board is the only one where the
connection of the two lines can be and is effectuated.
Fig. 7 will now show the details of the two lines to be connected, as also the
circuits connecting the operators' apparatuses.
The calling subscriber presses the calling key K at his end, closing the circuit
of his generator P, on the winding D of his own annunciator, located on half
board SR of the combination board R S of the exchange. (The book bat his
station is at that moment pressing on the lower contact, the telephone being
suspended at it) circuit P Kb IDP). The call is announced to the operator at
the board Sn who inserts in the multiple jack SB (a coull) the plug (fh m) of
one of the pair of flexible connecting cords at his disposal; tip f of the plug
comes then in contact with spring a of the jack; the insulated metal ring m of the
plug establishes communication of spring o with u, while sleeve h is in contact
with the metal ring o of the jack.
By means of the listening key (F F H) he listens to the caller's demands
(telephonic circuit: Ilchqq CItIki falt). Put me in connection with
section H or with subscriber No
of section H. as is usually done..

page_text: Now, naturally supposing that the subscriber wanted does not belong to the same
section as the calling subscriber, nor to the combined section of the combination
board at which the call is received, i.e. sections S and R (in which case the
connection is made without the help of another operator) the operator inserts the
second plug (f¹ h' m') of the pair of flexible connecting cords in the local jack of
the local telephone line (2) belonging to the board Sч required by the call.
The preliminary trial of the circuit can be made beforehand by touching the base U
of the jack with the tip of the plug, a sound being made in the telephone receiver t
should there already be somewhere, in that circuit, a plug in a jack. Every plug
has an insulated metal ring (m & m¹) which, when the plug is inserted in a jack,
connects up the springs o and ; this electrical communication between the
springs o and u by means of the insulated metal ring m, connects the line
and the base U with the local battery p which is thus able to allow the
preliminary trial of the circuit to take place through e po mu U f¹ Fik¹ It e
Should the line be clear, the insertion of the plug in the jack completes the
connection between the battery p and the line, and the current passing through
epomuz Ge works the galvanoscope G warning the operator stationed at the
board SH. The second operator Su, manipulating his listening key Y, communicates
telephonically with the first operator (circuit: Ita Fik¹ I t 1 C q q' h' cr)..
Notice of the connection required is transmitted by the first operator to the
second: "Connect up subscriber N°.... section H." During the transmission of
this order, the calling subscriber listens by means of the shunt telephonic
circuit 1 ki Ffalt I blch. The insertion of the first plug in the calling
subscriber's jack had the effect of automatically raising his annunciator drop.
(circuit e p o mu zde).
=
The second operator having received the above order, the first operator
The second
withdraws his plugs and is now free to attend to other calls.
operator in his turn, now inserts his plug (fhm) in the calling subscriber's jack SẼ
and is connected up to him through tlki Ffalt I blch g'q Clt; at the
same time, he has manipulated the key Y and has thus cleared the local inter-
communication line, which is now at the disposal of any other operator.
пр
The second operator establishes the communication with the called subscriber
In first of all touching with the tip of
as soon as he is informed, in the usual way.
his second plug the base U' of the jack Hs of the line jj' of the subscriber
wanted, he is warned if it is already engaged by a sound being made in his telephone.
receiver; if the base is already, through the insertion of some other plug in another
jack, in connection with the battery p. In this case, after notifying the calling
subscriber, the operator withdraws his plugs; if on the contrary, no sound is heard
in the telephone receiver t, it indicates that the line ; j' is clear; the operator
connects it up by inserting his plug (f¹ h¹ m) in the multiple jack Hg of the
called up subscriber; he calls him up by pressing the key kq which brings the.
battery P into action (circuit P¹¹¹ƒ³àª¹ j¹ Skjª¹ c¹h¹ q¹´P).
When conversation is set up, the operator withdraws by releasing the listening
key F F H, and substitutes the device clearing out drop for announcing that
conversation between the two subscribers has ceased and which is a shunt on the two.
circuits through h h¹ and ƒ Fikk F¹ƒ.
The telephonic circuits established while the two subscribers are conversing are
The devices for connecting the two lines at a combination board, are, in fact,
the two flexible cords of a single operator, and it follows that the general
intervention, in the system of an order transmitted locally by telephone between.
operators, is but transitory and leads to less complication than the ordinary
trunk lines (kept closed in circuit while conversation lasts) and which the use-
of several telephone exchanges renders necessary.

page_text: Notice that conversation between the subscribers is at an end is given by either
of them pressing his calling key (circuit: P k blch X Ffal P).
All the apparatuses at the disposal of an operator, Fig. 7, are placed in such a
way that the listening keys F F1 H, each provided with a pair of flexible cords,
are placed in the circuits, ahead of all the other apparatuses of which there is only
one set for all the pair of cords at the disposal of an operator, so that the devices in
circuit, behind the contacts i, and are common to all the pairs of cords and
listening keys of one operator; the two calling-up keys k and kq are used for
all calls made by one operator, the connections are always made by means of
the three wires i common to all the listening keys of one operator.
The automatic raising of each of the annunciators which indicate that
conversation has ceased (winding ) is ensured so long as it is not shunted on
the pair of flexible wires, the listening key F F H closing then by the contact
of spring H, the circuit e pH e.
In my description, I have intentionally chosen for example the application of
my system of combination boards with appliances of the most complex and most
recent multiple pattern, so as not to leave any doubt as to the universatility of its
applications.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The general application in telephony of the above described principle of
binary combinations for the purposes set forth.
2. The subdivision of the lines of a central telephone exchange into sections,
which allows of the application of the arithmetical principle of combinations,
(Fig. 1).
3. The binary association of the boards of two sections, constituting a combination
board, (Fig. 2).
4. The use of binary combinations adapted to the usual multiple double cord
switches.
5. The attribution to a definite combination board of the connections during
the communication between subscribers belonging to two sections.
6. The use of a telephonic order transmitted locally between the operators of
the exchange.
7. The methodical classification of sections in a certain order, particularly the
alphabetical order as above described.
8. The subdivision of the calls of one section between the various operators
at the boards of that section, limiting the intercommunication between the
operators.
9. The installation of the combination
the triangular diagram above mentioned.
Dated this 29th day of January 1895.
boards, in any manner derived from
EMILE ANDREOLI.