Improvements in Telephonic Installations.
Year: 1895

page_text: Date of Application, 6th July, 1895
Complete Specification Left, 6th Jan.. 1896-Accepted, 6th July, 1896
[Communicated from abroad by ED. BAIVY, of 75 Rue Lesbroussart, Brussels, in
the Kingdom of Belgium, Engineer.]
Improvements in Telephonic Installations.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby declare
the nature of this invention to be as follows:-
This invention relates to improvements in telephonic installations.
The characteristic feature of this improved telephonic installation is the
connection of the central station with the instruments of the customers in such a
manner that all manipulations beyond the telephonic communications are effected
upon the single-wire line, whereas the communications take place upon the double
wire line, this new combination resulting in such a simplification that the instal-
lations of the simple wire systems can be utilized for the new double wire system.
without modification of the appliances and of their connections, while at the same
time permitting the suppression of any source of electricity at the customers
instruments for the call and permitting the use of annunciators with exclusively.
automatic function, forming part of the new combination, whilst on the other hand
the system allows of the use of all kinds of microphones irrespective of their
acting with or without induction-coil, so that the advantage and saving resulting
therefrom for the whole arrangement, largely compensate for supplementary
expenses necessitated by the double wire of the line so that one can say that this.
is the telephonic installation for double wire systems in the simplest possible form of
construction.
This remarkable progress in the double wire installations is due to and realized
by the combination with the double-wire line, of an earth connection in common at
the central station and an earth connection at the instruments of each subscriber,
so that if the latter calls the central station, it is one of the wires of the line that
constitutes with these two earth connections one single wire line and that, if on the
contrary the station calls the subscriber, it is the other wire of the line that
constitutes a single-wire line with these same earth connections, whereas the
communication between two connected subscribers takes place over the circuit
closed by the two wires of the line.
Let us suppose two given wires of the double line connecting two subscribers
with the central station, further given a source of electricity and the earth
connections in common and the earth connection at the customer's instruments in
which the bells are included by the hook of his telephone. Further given the
jacks, the plug connections, the automatic annunciators, the clearing out annunciator,
the call buttons, the listening key and the source of electricity with continuous.
or alternate currents according to the nature of the call bells of the subscribers.
It will in the first instance be observed that apart from the automatic
annunciators all the accessories of the multiple board remain the same as for a.
simple wire system and that especially the jacks are made with only one
interruption and with two contacts, the massive part and the single blade,'
connected respectively to the wires of the double line, of which the opposite
extremities are likewise connected with two contacts at the subscriber's instru-
ments. The said massive parts are integrally connected on the one hand by the

page_text: battery to the earth in common to the central station by a simple auxiliary wire,
passing through the annunciators, and on the other by one wire of the line, the
hook of the telephone and the contact to the bell and earth at the subscriber's
instrument when the telephone is hooked on or at rest. The blades of the jacks
are likewise all connected, on the one hand, by contacts and the auxiliary wires or
connections to the annunciator and to the source of electricity and earth in
common to the central station and on the other hand by one wire of the line to the
respective contact at the customer's instrument.
The annunciators act automatically to engage as well as to release of the
indicator according to an appropriate permanent conjunction of this latter with
the armature of the electro-magnet, this conjunction being effected in the con-
structional form of the present example by coupling the armature to the frame
work of the indicator by an intermediate connecting rod. This arrangement
permits of disposing the indicator indifferently so that the same rises or falls in
order to show the number of the calling subscriber.
When it rises the fixed point of the pivot of the indicator is situated above the
electromagnet whereas in the case of falling, this point lies below.
The operation of this installation can now be very easily understood from the
preceding and in order to explain the same in all its simplicity we will follow
the operations effected between two subscribers and the official of the central
station.
One subscriber calls and for this purpose he only needs to unhook his telephone.
The hook while passing through the intermediate position connects two contacts
and closes the simple wire-circuit to the earth, causing a current to pass from the
source of electricity through the annunciator, the attracted armature of which lifts
the indicator. It is evident that the connection of the contacts aforesaid for the
call may likewise be effected by a special switch button with automatic rising after
depression for the call, but this would be one mechanism in addition and thus.
complicate the arrangement. As the intermediate position of the hook upon the
said two contacts is only temporary, because of its continuing to rise in order to
reach its resting position and to remain in the position for hearing, the indicator
would at once fall back if the circuit of the annunciator had not been closed again
at the same time by the armature itself upon an auxiliary earth connection by its
contact with a small spring, thus maintaining the indicator lifted and indicating
the call. It is evident that this auxiliary earth connection would not be necessary,
if instead of the automatic indicator an ordinary indicator were used the indicator
of which being engaged by hand.
The official then places his station into the circuit by manipulating the hearing
key in order to establish the respective contacts, he then introduces the pin into
the respective jack of the subscriber and communicates with him. The lifting of
the blade of the jack having broken the contact of the simple wire circuit of the
annunciator, the indicator falls back.
In order to ascertain whether the called subscriber is disengaged or in order to
test the line according to the time used, it is sufficient that the official touches the.
massive part of his jack and if the line is not occupied the official will hear
nothing, whereas he will hear a noise in his telephone in case the subscriber is
engaged. This noise is produced by the charge of any appropriate condenser
inserted into a shunt circuit of his post and to the earth. If now the subscriber is
occupied, one of the massive parts is in contact with the metal of a pin and as
during the communication the bearing key is engaged, the massive parts of all
jacks communicate with the source of electricity and the earth, so that if a second
pin is introduced making a contact with one of the massive parts the condenser is
charged according to the respective position of the hearing key of the official who
then hears the noise in question. For testing the line, the condenser may also be
omitted, if one will allow the annunciator, indicating the end of the conversation at
the occupied board to produce a slight movement during the test, which would no
longer be inconvenient, because this movement can not be mistaken for the

page_text: indication of permanent non-reply. This slight movement can be avoided in two
ways; first by disposing the coils of the two parts of the annunciator in such a
manner as to produce contrary magnetic effects caused by the circuits formed in
the position occupied on the annunciator or also by replacing the condenser by a
resistance performing the same duty and decreasing the current sufficiently in
order that the same no longer actuates the annunciators.
If on the contrary the called. subscriber is disengaged, it is sufficient that the
official inserts the plug into one of the corresponding jacks, which permits him to
first ring the subscriber over the simple wire by closing the respective circuit by
the depression of the call button the rising of which subsequently closes the double
wire circuit of the line.
In this system the clearing out annunciator always indicates to the official that
the called subscriber has replied without the official being obliged to execute any
manipulation whatever for this purpose.
In fact as long as his hook has not risen again into the highest position and
remains on the earth connection, clearing out annunciator is traversed by a current
emitted from the source, the circuit of which is closed by the two respective earth-
connections and which lifts the indicator thus indicating that the subscriber does
not reply. But from the moment when the subscriber produces the simple
operation consisting in unhooking his telephone for replying, the circuit is broken
and the indicator falls and thus indicates that the two subscribers are in communi-
cation and rises again at the end of the communication when the subscribers place
their receivers back on to the hooks, until the official withdraws the plugs and thus
breaks the circuit.
In the simplest constructional form of connecting the line with the corresponding
contact of the subscribers instruments the one line which transmits the currents for
the call traverses in the case where no induction coil is used, the telephone and the
microphone and in case where induction coils are used, the line traverses the
secondary circuit and the telephone. If for any reason one wishes to prevent
the current from traversing these resistances it would be sufficient to establish a
direct connection of the line with the contact. This connection being a simple
wire united with the line in front of the telephone and to which likewise corre-
sponds a special wire at the central station, where it directly connects the line with
the indicator, while not in the least complicating the installation because of its
being neither connected to the jack nor to the key.
It results therefrom that the installation is applicable with the same facility to
all systems irrespective of the nature of the microphones employed and whether for
the microphones without coil the pile be arranged at the subscribers apparatus or
at the central station.
This new automatic annunciator the essential feature of which is a constant
connection between the indicator and the armature and which is described in its
application to double wire systems can be adapted with the same facility to
ordinary simple wire systems and in this case the same is advantageously
constructed in the following manner.
The characteristic part of this modified form of connection is the rigid fixing of
a lever upon the armature with which latter it pivots when said armature is
attracted, so that the lever rises and thus lifts at the same time the indicator
which pivots on the point of fixation and to which the lever is jointed by a small
connecting rod.
If now by the aid of the magnets or by another source of electricity at the
subscribers instrument a current is sent over the line, this current will pass into the
annunciator which attracts the armature and raises the lever, which latter produces
a contact with a spring and closes the respective circuit in such a manner that the
current from the source of electricity maintains the indicator in lifted position up
to the moment when the official at the central station inserts a plug into one of the
jacks of the subscriber and thus breaks the contact, the result of which contact
breaking is that the current from the source to the annunciator is cut off so that

page_text: the indicator of the latter falls back. The spring aforesaid instead of being
arranged above the lever, may also be arranged below the lever and so as to
depress the same by its own weight when the current does not pass and to thus
break the contact, whilst this latter is closed by the elasticity of the spring, from
the moment when the current passes into the annunciator and lifts the lever.
It is evident that these arrangements apart from their great simplicity moreover
permit of an easy transformation of all annunciators existing in automatic
annunciators.
Dated this 6th day of July 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements in Telephonio Installations.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, 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 this invention is to simplify as much as possible telephonic
installations arranged on the two wire system, more particularly at the central
or exchange office, both by simplifying the parts themselves and their connections
and also the operations to be effected by the attendants at such exchange.
The principal characteristics of my said invention consist in the special arrange-
ment of the call devices or annunciators and of the clearing out devices which
indicate that the conversation is at an end and also in the special manner
in which such devices are interposed in the circuit and connected with the
other parts.
In effecting the double purpose indicated above, the most satisfactory results
are obtained by employing annunciators which actuate their hammers or pendulums
automatically both for raising and depressing them, or vice versa, by a simple
suitable mechanical connection of the armature with the hammer of the
annunciator, which arrangement supersedes all the electrical connections which
are requisite in automatic annunciators in which an electro-magnet forms the
re-engaging device.
In the accompanying drawings
Figures 1, 2 and 3 represent three descriptions of automatic annunciators in side
elevation.
Figure 4 is a diagrammatic view shewing the arrangement at the exchange office
for connecting up two stations, and,
Figure 5 is a diagrammatic view of a modified manner of connecting the
annunciators.
The annunciators are of the ordinary construction with the exception of those
parts which effect the automatic action of the hammers or pendulums which parts
are extremely simple.
In the types shewn in Figures 1 and 2, a lever is integral with the armature a
and is suspended in a bracket c which is fixed upon the case of the electro-
magnet E.
In Figure 1 the front extremity of the lever is bent so as to form a
hook which engages with a similar hook arranged upon the hammer which is
pivoted in the ordinary way. With the foregoing arrangement, when the armature
is attracted the lever is raised and with it the hammer and both fall when the
current is interrupted. In Figure 2 the hook is replaced by a link m which is
jointed upon the lever and the hammer, the other parts remaining the same.

page_text: In Figure 3 the armature is shewn pivoted at its base and provided with a
projecting portion p; the lever is replaced by a connecting rod t connected to a
bent lever which is pivotally mounted in a bracket c and carries the hammer v.
In this case when the armature is attracted it pushes back the rod t which causes
the lever to rock and so raise the hammer which in again falling causes all the
parts to re-occupy their initial position.
It will be readily understood that with such an arrangement the circuit in which
the coil of the electro-magnets E is interposed is alone sufficient to automatically
actuate the hammer in both directions.
a "ringing-up" or
Now in inserting this type of annunciator, whether as
"clearing out" device, in a two wire circuit connecting two stations and passing
through the central office in the special manner which forms the principal
object of my invention, the number of parts and connections which form the
installation is reduced to a minimum and the operations to be effected by the
exchange attendant are confined to the manipulation of the pins of the "jacks."
and of the key of his station, since he will no longer have to concern himself with
the hammers which assume automatically the positions which correspond to the
functions they are to fulfil and in addition effect that special function which consists
in intimating to the exchange attendant that the subscriber whom he has rung up
has replied.
A usual mode of inserting aununciators in the circuit, according to the peculiarities
of the system to which they are to be adapted, is based upon that property of a two
wire telephone installation which consists in its being capable of being connected,
to earth at one of its points, without thereby producing any derangement, provided
only that such earth connection is effected in such a manner as not to disturb the
equilibrium of the circuit.
In utilising this property the annunciators are inserted in a shunt of the double
circuit, a point on the said shunt being put to earth but in such a manner that the
equilibrium of the circuit is not disturbed by such insertion.
Now it is evident that if the annunciator were inserted in one branch of the shunt
on one side of the earth connection, its coil would create a resistance which would
disturb the equilibrium of the whole circuit whilst this defect is wholly obviated by
inserting in the other branch a coil having the same electrical measurement as the
coil of the annunciator, as the equilibrium is then perfect and communication is in
no wise affected.
Such an arrangement is represented in Figure 5 of the drawing in order to
make the foregoing quite clear and it will be seen that the earth connection is
situated in the middle of the shunt between the annunciator coil A° and the
corresponding coil W.
In practice, however, the most simple manner of carrying out this object is of
course chosen and this consists in transferring the earth connection to the middle
of the annunciator coil itself, by dividing it in halves which form exactly similar
coils and thus preserve the equilibrium of the circuit, and the same result is attained
more economically and with a more compact arrangement, as may be seen on referring
to the clearing out annunciator shewn as forming part of the telephonic installation
represented by way of example in Figure 4.
As the equilibrium which is maintained in the circuit in the above manner is
likewise not affected if a source current, a battery P for example, be interposed
in the connection between the shunt and the earth, as shown in Figure 4, it is
evident that by disconnecting the double circuit and thus decomposing it into
single lines which in their turn are put to earth on one side or the other of the
annunciator, such single lines cause the annunciator to act by means of that half of
the coil which is situated on the side where the corresponding single circuit is run
to earth.
:
It follows then that if rendered necessary or desirable by the different forms of
installation which may be employed, the coil W in Figure 5 may also serve as the
coil of a second annunciator instead of serving simply as a coil for maintaining

page_text: equilibrium, and it will be capable of acting independently of the other annunciator A
and the one or several coils inserted in the shunt on the double circuit may them-
.selves be subdivided several times and such subdivisions may be utilized for effecting
the most diverse functions.
By arranging the automatic annunciators above described in shunts upon the
circuit in the manner described they may also be so disposed as to act in conformity
with any description of two wire telephonic installation, but if in any description
of installation whatever, the clearing out annunciators must always be inserted in
shunt upon the double circuit as described, this does not always apply to the
-ringing up annunciators which may, in certain installations, be so inserted as
not to remain in derivation upon the circuit, but, on the contrary, may be put
out of circuit whilst communication is established whilst at the same time the
automatic carrying out of their functions is assured by the insertion of a special
device such as is employed in the installation shewn by way of example in
Figure 4:
:
In this form of installation no source of current is provided at the stations of
the subscribers X, X' for ringing up the exchange, this current being supplied by
one battery P only which is provided at the exchange office, one pole of such battery
being put to earth at To whilst the other pole supplies with current all the ringing
up annunciators A, A' which are inserted normally, that is to say when at rest,
in the line wires L', L' of the double circuit, connected with the battery P by a
wire L which establishes communication between the contacts K° and the blades J
of the jacks of which M, M are the plugs which are connected by the wire L³ to
the line wires L2, L2 on the one hand and to the contact blades arranged above
the levers of the annunciators A, A¹ on the other hand, the said levers / being put
to earth at T³, T³.
The clearing out annunciator A' is inserted in shunt upon the double circuit L' L'
as above described, and is put to earth at To through the battery P. The said
aununciator is interposed in the circuit or put out of circuit by means of the
contacts K, K of the key of the attendant which are connected with that portion
of the double circuit which forms the connection between the cords F F', such cords
having at their extremities the pins with two contacts e, f, the contacts fƒ corre-
sponding to the blades J of the jacks whilst the others e, e, correspond on the
one hand to the plugs M M and on the other to the call pushes R R which are
normally closed upon the contacts K, K¹ and serve, by means of the contacts q, q',
to close the circuit of the common source G put to earth at T for actuating the
call bells S, S¹ at the subscribers stations.
The annunciator A' is thus in circuit when the contacts K, K° of the key are
closed upon the blades DD of the shunts, whilst by closing them upon the blades o, o
the attendants station X is put in derivation upon the double circuit the derived
circuit of which station is also put to earth at T, a resistance coil Ro being
interposed.
At the subscribers stations X, X' the line wires L', L' of the double circuit
terminate in the contacts Y, Y and the wires L³, L' connect with the telephone
suspension hooks B, B which in their position of repose connect the bells S S¹ to
earth at T, T' by means of the contacts Z, Z.
The series of operations can readily be understood from the above description
and takes place in the following order assuming that X wishes to communicate
with X¹.
First operation. Ringing up the central office.-The subscriber X simply has to
unhook his telephone; the hook B rises and when it reaches the position B¹ it
momentarily connects the contacts Y Z closing the circuit T L J L P To of the
annunciator A which disengages, that is to say raises, its hammer or pendulum v by
means of the lever acting by the attraction of the armature a.
The hook continues to rise until it reaches the position B2 and breaks
contact between Y and Z so that the hammer v will fall back; now in rising
the lever has been put in contact with the blader and has thus closed the

page_text: circuit TL'L'B' LJLPTº passing also into the annunciator A which thus
indicates a call.
Second operation. Communication of the attendant with the subscriber giving
the call. The attendant introduces the pin into the corresponding jack and raising
the blade J with the contact f he breaks at K° the circuit of the annunciator A
which then resumes its position of rest, whilst the contact e touches the plug M;
then by placing the contacts K K of the listening key upon O O, the attendant
connects his own station X and that of the subscriber X by a two wire circuit and.
the subscriber can state his requirements.
Third operation. Testing the line and calling the subscriber asked for.-The
attendant touches the plug M of the jack of the subscriber asked for with the.
point of the pin. If this subscriber is free such contact produces no effect since
it closes upon the attendant's station the circuit T L M ƒ KOT which contains.
no source of current. If on the other hand the subscriber X should be occupied..
a pin would be inserted in one of the jacks and all the corresponding plugs M
would be connected to earth at To by the circuit T P K O Mf and as this
circuit contains the source of current P, the attendant would hear a click in his
telephone X°. This click will be attenuated by the resistance coil R° interposed.
in the earth connection T of the attendant's station. In practice this earth will
be taken from the middle of the resistance coil of the station itself, but for greater
clearness it has been shewn separately in the drawings.
If the subscriber who has been asked for is free, the attendant rings him up by
depressing the push R¹ and thus closing the circuit T₁ q¹e M L² T¹ which contains
the source of current G which causes the bell S¹ to act.
Having done this, the attendant by means of his key, puts his station X° out of
circuit and puts in circuit the clearing out annunciator A', in such a manner that
if the subscriber X₁ wishes to reply he has simply to unhook his telephone in
order to do so, the hook B assumes the position B2 and the double circuit is closed
upon the two stations ready for conversation to take place and the clearing out
annunciator remains in derivation upon the said circuit. Now first of all it
has intimated to the attendant that the subscriber has replied, because as
long as the hook B remains depressed the circuit T' L' M/D P T is closed
upon the corresponding half of the annunciator coil and keeps the pendulum v
of the said annunciator raised, but as soon as the hook rises and breaks this
circuit, the pendulum falls back and the attendant knows that the subscribers are
in communication.
The termination of such communication is intimated to him in the same manner,
that is to say, the subscriber simply by replacing his telephone upon its hook
re-establishes the same circuit and the pendulum again rises.
The attendant then replaces the parts in their position of repose by withdrawing
the pins and putting the key out of circuit, that is to say in the position which it
is represented as occupying in the drawing.
It will be remarked in the first place that the pins, the jacks and their
connections are quite as simple as in a single wire installation and that the
switches, tables and the like can thus be utilised without appreciable alteration
in this system of two wire installation; also the same source of current serves for
both the ringing-up and for the clearing out annunciators and that no source of
current is required at the subscribers' stations; further that the attendant has now
only his key and the pius to manipulate and above all that he is advised of
the subscriber's having replied, which is not effected by any other system,
by reason of the special manner in which the clearing out annunciator is
inserted in the circuit. It should also be remarked that this last advantage
is still obtained if instead of the automatic annunciators above described, the
ordinary form of annunciator is employed; but in this case the attendant will
have to see to the pendulums, so that all the advantages of my improved system
are not obtained.

page_text: 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 in two wire telephonic installations, is-
1. The special manner of interposing the annunciators in a shunt of the double
circuit which is put to earth at its middle, in such a manner that the annunciator
coil is interposed in one of the branches of the shunt and a coil of exactly similar
electrical measurement is interposed in the other branch so as to keep the equilibrium
of the double circuit unimpaired.
2. A modification of the manner of interposing the ringing-up annunciators which
consists in arranging within the reach of one of the movable parts of the said
annunciators, such as the armature or the pendulum, a part which in making contact
with such movable part closes upon the coil of the annunciator a circuit different
from its normal circuit which normal circuit is then broken, substantially as
described and for the purpose specified.
3. In combination with the methods of interposing as above described automatic
non-polarised annunciators characterized by a constant articulated connection
between the armatures and the pendulums, substantially as above described and as
represented in the accompanying drawing.
Dated this 2nd day of July 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.