Improvements in and relating to Telephonic Systems.
Year: 1894

page_text: Date of Application, 10th Apr., 1894
Complete Specification Left, 10th Jan., 1895-Accepted, 6th Apr., 1895
PROVISIONAL SPECIFICATION.
Improvements in and relating to Telephonic Systems.
I, HENRI CARBONNELLE, of No. 24 Rue Rogiers, Brussels in the Kingdom
of Belgium, Electrician, do hereby declare the nature of this invention to be as
follows:-
My invention relates to telephonic systems and comprises an improved arrange-
ment of micro-telephonic lines for the transmission of speech, enabling the users of
the telephone to dispense with a source of electricity on the premises.
The object of this invention is to arrange and combine telephonic connections
between the main or central station and the local or private stations at the
customers' houses, without the assistance of an induction coil and with a microphone
of suitable resistance and sensitiveness, in such a manner as to attain the following
results:
(1) No source of electricity need be provided on the premises of the customer or
subscriber.
(2) The source of electricity, which has hitherto been arranged in the customer's
house, is replaced by another source of electricity arranged at the central station
and interposed between each pair of cords of the "
"multiple or other switch-boards.
(3) Where double wires are used, one battery of cells or accumulators is
sufficient to work the whole network of lines.
(4) All the methods of exchanging "calls" or signals hitherto employed, and
also the existing means for producing such siguals or calls may be retained;
though, if preferred, a special device may, for this purpose, be readily substitute l
for the old devices, in which case the source of electricity is transferred to the
central station, where the "call" of the customer is thus directly heard.
(5) A very considerable reduction in the number of batteries operating at the
same time, and in the quantity of electrical energy expended; and
(6) The transfer or conversion of the lines may be effected without causing any
interruption or disturbance in the operation of the whole network.
According to my invention the subscriber "calls" the central station either by
means of an alternate-current device or a continuous-current device. In the
former case, a magneto dynamo of the well known construction or another suitable
device is provided on the customer's premises, and can be made to generate a
current which will cause the index-shutter at the central station to drop. In the
latter case the circuit of a battery may be closed by pressing a button; such
battery being constantly kept charged at the central station. The current as it is
being sent on to the line from which the call proceeds, passes through a signalling
device of suitable construction, and in so doing opens or otherwise operates the
index-plate, thereby attracting the official's attention to the call. The current of
the call-battery of the central station is counterbalanced by a condenser arranged
on the subscriber's premises, or by a battery in opposition with the battery at the
central station. It will be understood that these two batteries should have the
same electro-motive force. If a condenser is used it opposes the passage of a con-
tinuous current, as long as it is in circuit but when the button or knob, hereinabove
mentioned is pressed said condenser is switched out of circuit, and the battery
current is enabled to pass. The opposition battery, which may be substituted for
the condenser, acts in the same manner. The customer's or branch station is

page_text: provided with a call or signalling device arranged to receive the call proceeding
from the central station. This signalling device is set in operation by a periodical,
undulatory, continuous, or other current, according to the arrangement preferred
and to the kind of call it is desired to produce, that is to say according as it is an
audible, optical, or other call or signal.
The induction coil on the customer's premises is dispensed with. The microphone,
when in position for conversation is directly connected to the line, and connected in
series with the telephonic receiver. As before stated the current which passes
through the microphone and receiver proceeds from the central station.
For the sake of greater clearness, I will describe the operation at the central
station as it takes place in two different cases, viz.: In the case of single wire
lines, and in the case of double wire lines. Mixed arrangements belong to the first
category. The two cases mentioned I will further subdivide into such as have
calls operated by alternate currents, and such as have their calls actuated by
continuous currents.
In the first case and when the subscriber communicates with the central office by
means of a call operated by alternate currents, the only alterations necessary to
enable the central office or station, having "multiple boards" to be operated in
accordance with this invention are (a) the introduction of a battery, consisting of
one or more cells, between each pair of cords of the multiple boards; and (6) the
removal of the induction coil from the local or branch station attended to by an
official of the company, in the same way as the said coil was removed from the
subscriber's private station. The receiver and battery are connected with the
microphone in series. The special battery of the local microphone, may however,
be dispensed with, the microphone and receiver being connected in series, so that
one end of the wire connecting them leads to the earth, and the other to a "jack
wherein is inserted the second peg of the pair of cords, the first peg being placed in
the "jack" of the subscriber or customer who has used the call device. The
remaining parts of the existing arrangement, at the central station, may continue
the same as before, and need not be further described here.
When the subscriber uses the call device operated by a continuous current the
two alterations indicated above are made first, in addition to which, a battery of
sufficient electro motive force is introduced between the earth and the ends of all
the customers' lines, after these lines have passed the signalling devices. One
battery which I shall name "call battery," is quite sufficient to perform all the
work at the central station.
In the case of double wire lines it will be understood that the supply of electricity
may be provided for in the same manner as has just been described in reference to
single wire lines. But in addition to this instead of using one battery for each pair
of cords in sending the microphone current to the customer a single battery may
here be used to work the whole arrangement at the central station and all the pairs
of cords on the conductors of the said battery are connected in parallel. Batteries
of this class and used in this manner I shall call "microphone batteries." In the
same way as in the first case, one microphone battery will be sufficient to work the
microphones of all the subscribers or customers as well as the microphones of
the officials at the central station.
In order that the nature of my invention may be more clearly understood I will
proceed to describe by way of example one method of carrying it into practice.
I will first describe a customer's station with a call device operated by alternate
currents. The "line" wire first arrives at a binding post or screw at the entrance,
which communicates with the commutator hook. This book bears upon either of
two contact pieces according as the receiver is suspended from, or taken off, its
book, and causes the current to pass through either a magnetic call bell of ordinary
construction, or through a microphone of suitable resistance and sensitiveness.
A telephone receiver is connected in series with the microphone.
The binding posts at the exit end, connect the line wire to the earth wire after
baving travelled through the usual circuit. The remaining connections in the

page_text: magnetic call-bell arrangement are made in the same manner as in existing
apparatus.
The subscriber's or customer's line is led at the central station to the "jacks"
and then through the signalling or call device to the earth or the return wire.
The microphone and receiver operated by the attendant at the station are plugged
into the line when a call is received. Switch pegs or plugs with cords are connected
to the key of the multiple switch-board and a battery is interposed between each
pair of the switch-board cords. It is intended to supply electricity to the two
microphones of the subscribers or customers placed in communication by the said
cords.
The operation of this arrangement is as follows: When the telephone clerk
wants to communicate with the customer, he or she inserts one of the pegs or plugs
into one of the "jacks" the other peg resting with its base or bottom upon the
table and forming the earth connection. The key or switch being then properly
turned on, the circuit of the station call battery is closed through the clerks
telephone and microphone and through the cords and the pegs one of which forms
the earth connection through the table, while the other is connected with the line
and if the telephone hook happen to be raised at the subscriber's station the current
traverses the subscriber's microphone and telephone and then proceeds to earth.
When the attendant at the central station wishes to place in communication two
customers, he gives the usual signals and places the pegs into the corresponding
"jacks" appertaining to the customers who are about to enter into conversation.
He then places the key upon the call device, which is to announce the end of the
conversation, and within the circuit of which is comprised the microphone battery
which is to actuate the microphones of the persons who are conversing, through the
medium of the pegs with their cords, and of the lines. During the conversation,
the current passing through the call device is not sufficiently intense to cause the
index-shutter to drop; but it acquires a sufficient intensity for this purpose as soon
as the customers hang up their receivers again and give the handle the usual turn.
The signalling or call devices of the branch stations being exactly the same as
those of the central station on certain well-known lines, such as the Belgian lines,
it is unnecessary further to dwell here on this feature. The key or switch arrange-
ment of the multiple board requires no alteration whatever, when it is desired to
operate the signalling devices.
I will now describe the arrangements at a subscriber's or branch station which
is arranged to communicate with the central station by means of an electric
call-bell. The "line" wire leads up to the commutator hook which serves to
carry the receiver. The said hook bears against one of two contacts according
A knob or buttor
as the telephone is suspended from, or taken off, its hook.
is provided which when pressed transmits the call to the central station by
bringing the line into connection with the earth. When said switch is in its
normal position a call sent from the central station sets in operation a suitable
notifying or signalling device and a condenser is provided in series with the said
signalling device which prevents the same being operated by the ordinary call
battery. Said condenser may be substituted by a battery of diminutive size but of
the same electro-motive force as the ordinary call battery.
The only difference between corresponding central station corresponding to this
arrangement of subscribers station and the arrangement hereinbefore described is
the addition of a call-battery one pole of which leads to earth and the other to the
extremities of all the customers' lines.
While at rest, the call battery keeps all the lines and the condensers of the
customers in the charged condition.
When either of the customers who are con-
versing presees this knob or button the telephone being on its hook it will be seen
that the connection of the line with the condenser is cut off, the line being connected
direct to the earth or to the return wire. A derived current from the call battery
will then pass through the call device, and cause the shutter to drop; and through
the customer's line to earth.

page_text: The official at the central station, in order to call a customer, inserts one of the
pegs into one of the customer's jacks, and then sends through the line a current
capable of operating a suitable call at the customer's station. The key or switch
arrangement of the multiple boards requires no alteration. The current employed
may be either periodical, undulatory or of any other suitable nature, according to
the type of apparatus used, and to the nature of the call (either audible or optical,
or other) which it is desired to produce.
Should it be desired to place at the customer's station a small battery of equal
electro-motive force with, and in opposition to, the call battery,- -as a substitute for
the condenser just mentioned, this would involve no change so far as the
customer's station is concerned, as the connections would remain exactly the same,
though the call device in this case may be an ordinary vibrating bell. When the
attendant at the central station wants to use the call device, it is only necessary for
him to increase the tension of the opposing battery.
The arrangement of such a small battery on the customer's premises would
occasion him no expense, since the battery would consume no extra current, its
charge being maintained in a uniform condition by the call battery arranged in
opposition to the other, at the central station.
When it is desired to substitute for the microphone batteries one single battery
to operate a double wire line or series of lines I provide two conductors extending
from the said battery. Along these conductors, the pairs of connecting cords are
arranged in parallel. I can thus join any pair of line wires by any two connecting
cords one from each set including the microphone battery between them. The
subscribers' stations are arranged in a manner similar to that hereinabove described
except that a return wire is taken to the central station instead of going down to
the earth on the customer's premises.
The microphone battery is alone sufficient to feed the cords whereby two
subscribers are placed in communication with each other or with the local stations
placed under the control of the officials of the company. It will also be seen that
whatever the number of subscribers or customers which the microphone battery is
to supply with current, there can rise no confusion in the communication.
In the case of town connections a double wire circuit serving for telephonic
purposes only is required.
If the customer's line be a double wire line it is sufficient to branch it off direct,
without, passing through the "translator" as in that case there is no condenser to
be met, or passed through on the line.
If the customer's line be a single wire line a connection should be made through
the medium of the "translator."
In the foregoing description no special microphone has been referred to in detail,
as I have found by experience that certain microphones, the proportions or
dimensions of which are well defined, when they are traversed by currents of
sufficient tension will be found satisfactory enough when operating at great
distances even though no induction coil be used. But I may state that I have
obtained the best possible results that it has been possible to accomplish hitherto by
the employment of a special type of apparatus forming the subject matter of a
separate Patent No. 7132 April 10th 1894. This being so I need not further
describe it here.
I have hereinabove passed in review & number of particular cases likely to occur
in practice, in order to show with what facility my improved arrangement is
applicable to each. It will be seen that my invention for all practical purposes
remains the same, with the exception of certain alterations which the peculiar
circumstances of the case, or the special object in view, may demand. It will of
course be understood that I cannot possibly give a detailed description of its
application to all the different types of switchboard used at present, or which may
be used in times to come, in the different central telephone stations; but such details
as I have given will be sufficient to show that there is no case to which my invention
will not successfully apply, while the trifling alterations or modifications which

page_text: ntual practice may demand in a given case will readily suggest themselves to any
skilled electrician.
I have only referred above to currents generated by ordinary batteries, but it will
he obvious that ordinary batteries may easily be replaced by storage batteries or
other sources of electricity.
The advantages arising from my improvements in telephone connections are as
follows:
1. No battery need be arranged on the customer's premises and all the current-
producing elements or cells may therefore be centralized, and kept under control,
at one station; it follows therefore that
(a) A considerable amount of labour is saved, as there is no occasion to keep
the batteries in repair etc., and
(6) In offices or at stations where there are batteries fitted up, the necessary
conditions for insuring their durability and continuance in working order,
may be easily fulfilled.
2. The number of current-producing or operating elements to be kept charged at
the same time is considerably reduced. Thus in the case of single wire lines, at
least four-fifths of the battery cells may be dispensed with; while in the double
wire lines, the number of cells may still further, and to a very considerable extent,
be reduced.
3. The amount of electrical energy expended is also very materially reduced.
Taking, for example, a double wire line in connection with my improved
microphone, it may be sufficient to employ one microphone battery only supplying
one ampere at 1-5 volts to operate a series or network of telephone lines comprising
three thousand subscribers, assuming that it may be necessary at any moment to
place one-fifth of the total number of subscribers in communication with a second
fifth of that number at the same time.
4. Satisfactory operation is better ensured, inasmuch as
(a) Should a battery be defective, the telephone clerk is in a position
immediately to remedy the defect by changing the pair of cords;
(b) The microphones are not liable to be burnt (or if burnt at all, will be so to
a far less extent than hitherto) by the sparks produced in breaking circuits,
since the quantity of electrical energy passing through them is a great
deal less than that which passes through the microphones in use at the
present time.
5. The induction coil is dispensed with.
6. Such alterations as are necessary at the existing central stations, to work the
telephone on my improved system, may be made with great facility.
7. The same remark applies to the customer's or branch offices, which may be
left practically as they are.
8. New stations, specially constructed with a view to the adoption of my improved
system will be found less cumbersome and less extensive than stations of the old
arrangement.
9. The apparatus now in use may be replaced successively without any
interruption in the performance of the usual work, as a new station fitted up in
accordance with my invention, will operate very satisfactorily in conjunction with
one of the old stations.
10. The distance at which telephonic communications may be exchanged is
considerably extended, as the resistance of a conductor is greater when it is
traversed by an alternate current than when it is by a continuous current.
11. No such powerful induction as alternate currents in an induction coil
necessitate need be used here, the current being direct.
Dated this 10th day of Anril 1894
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: Improvements in and relating to Telephonic Systems.
I, HENRI CARBONELLE, of No. 24, Rue Rogiers, Brussels in the Kingdom of
Belgium, Electrician, 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 relates to telephonic systems and comprises an improved arrange-
ment of micro-telephonic lines for the transmission of speech, enabling the users of
the telephone to dispense with a source of electricity on the premises.
The object of this invention is to arrange and combine telephonic connections
between the main or central station and the local or private stations at the
customers' houses, without the assistance of an induction coil and with a microphone
of suitable resistance and sensitiveness, in such a manner as to attain the following
results:
(1) No source of electricity need be provided on the premises of the subscriber.
(2) The source of electricity, which has hitherto been arranged in the
subscriber's house, is replaced by another source of electricity arranged at the
central station and interposed between each pair of cords of the "multiple" or
other switch-boards.
(3) Where double wires are used, one battery of cells or accumulators is
sufficient to work the whole network of lines.
(4) All the methods of exchanging "calls" or signals hitherto employed, and
also the existing means for producing such signals or calls may be retained;
though, if preferred, a special device may, for this purpose, be readily substituted
for the old devices, in which case the source of electricity is transferred to the
-central station, where the "call" of the subscriber is thus directly heard.
(5) A very considerable reduction in the number of batteries operating at the
same time, and in the quantity of electrical energy expended; and
(6) The conversion of the lines may be effected without causing any interruption
or disturbance in the operation of the whole network.
According to my invention the subscriber "calls" the central station either by
means of an alternate-current device or a continuous-current device. In the former
case, a magneto dynamo of the well known construction or another suitable device
is provided on the subscriber's premises, and can be made to generate a current
which will cause the index-shutter at the central station to drop. In the latter case'
the circuit of a battery may be closed by pressing a button; such battery being
constantly kept charged at the central station. The current, as it is being sent on
to the line from which the call proceeds, passes through a signalling device of
suitable construction, and in so doing opens or otherwise operates the index-plate,
thereby attracting the official's attention to the call. The current of the call-
battery of the central station is counterbalanced by a condenser arranged on the
subscriber's premises, or by a battery in opposition with the battery at the central
station. It will be understood that these two batteries should have the same
electro-motive force. If a condenser is used it opposes the passage of a continuous
current, as long as it is in circuit but when the button or knob hereinabove
mentioned is pressed the said condenser is switched out of circuit, and the battery
current is enabled to pass. The opposition battery, which may be substituted for
the condenser, acts in the same manner.
The subscriber's station is provided with a call or signalling device arranged to
receive the call proceeding from the central station. This signalling device is set
in operation by a periodical, undulatory, continuous, or other current, according
to the arrangement preferred and to the kind of call it is desired to produce, that is
to say according as it is an audible, optical, or other call or signal.

page_text: The induction coil on the subscriber's premises is dispensed with. The micro-
phone, when in position for conversation is directly connected to the line, and con-
nected in series with the telephonic receiver. As before stated the current which
passes through the microphone and receiver proceeds from the central station.
For the sake of greater clearness, I will describe the operation at the central
station as it takes place in two different cases, viz.: In the case of single wire lines,.
and in the case of double wire lines. Mixed arrangements belong to the first
category. The two cases mentioned I will further subdivide into such as have
calls operated by alternate currents, and such as have their calls actuated by
continuous currents.
In the first case and when the subscriber communicates with the central office by
means of a call operated by alternate currents, the only alterations necessary to
enable the central office or station, having "multiple boards" to be operated in
accordance with this invention are (a) the introduction of a battery, consisting of
one or more cells, between each pair of cords of the multiple boards; and (b) the
removal of the induction coil from the local or branch station attended to by an
official of the company, in the same way as the said coil was removed from the
subscriber's private station. The receiver and battery are connected with the
microphone in series. The special battery of the local microphone, may however,
be dispensed with, the microphone and receiver being connected in series, so that
one end of the wire connecting them leads to the earth, and the other to a "jack
wherein is inserted the second peg of the pair of cords, the first peg being placed in
the "jack' of the subscriber or customer who has used the call device. The
remaining parts of the existing arrangement, at the central station, may continue
the same as before, and need not be further described here.
"
When the subscriber uses the call device operated by a continuous current, the
two alterations indicated above are made first, in addition to which, a battery of
sufficient electro motive force is introduced between the earth and the ends of all
the subscribers' lines, after these lines have passed the signalling devices. One
battery which I shall name "call battery," is quite sufficient to perform all the
work at the central station.
In the case of double wire lines it will be understood that the supply of
electricity may be provided for in the same manner as has just been described in
reference to single wire lines.
But in addition to this instead of using one battery for each pair of cords in
sending the microphone current to the subscriber, a single battery may here be
used to work the whole arrangement at the central station and all the pairs of cords
on the conductors of the said battery are connected in parallel. Batteries of this
class and used in this manner I shall call "microphone batteries." In the same
way as in the first case, one microphone battery will be sufficient to work the
microphones of all the subscribers as well as the microphones of the officials at the
central station.
In order that the nature of my invention may be more clearly understood I will
proceed to describe the same by way of example with reference to the accompanying
drawings, in which:
Figure 1 is a diagram of a customer's station with a call device operated by
alternate currents.
Figure 2 is a diagram of the central station.
Figure 3 is a diagram of a subscriber's or branch station arranged to communicate
with the central station by means of an electric call bell.
Figure 4 is a diagram of the corresponding central station and
Figure 5 is a diagram showing the alteration which should be made when it is
desired to substitute for the microphone batteries one single battery to operate a
double wire line or series of lines.
Referring to the diagram Figure 1 the "line" wire L first arrives at a binding
post or screw a which communicates with the commutator hook C. This hook
bears upon one or the other of two contact pieces for g according as the receiver

page_text: is suspended from, or taken off, its hook, and causes the current to pass through
either S, which is a magnetic call bell of ordinary construction, or through M',
which is a microphone of suitable resistance and sensitiveness, provided with its
diaphragm m. T is a telephone receiver connected in series with the microphone.
T' designates the earth or the return wire.
The binding posts 6 and e, at the exit end, connect the line wire L to Te' after
having travelled through the usual circuit. d is the binding post for a current
traversing the microphone and the receiver when in position for conversation.
The remaining connections in the magnetic call-bell arrangement are made in the
same manner as in existing apparatus.
Referring to the diagram of the central station shown in Figure 2 L is the
subscriber's or customer's line leading up to the "jacks" J, J, J³, J and then
through the signalling or call device A' to the earth or the return wire Te².
M² and T2 are respectively the microphone and receiver operated by the attendant
at the station. m² is the diaphragm, and P¹ the battery of the said microphone.
Switch pegs or plugs F F with cords are connected to the key of the multiple
switch-board. A' is the device for notifying that the conversation is at an end.
P is a battery interposed between each pair of the switch-board cords. It is
intended to supply electricity to the two microphones of the subscribers placed in
communication by the said cords.
I will now describe the arrangements at a subscriber's or branch station which
is arranged to communicate with the central station by means of an electric call-
bell as shown in Figure 3. The "line" wire L leads up to a commutator hook C
which serves to carry the receiver T¹. The said hook Ċ bears against one of two
contacts for g, according as the telephone is suspended from, or taken off, its hook.
A knob or button B is provided which when pressed transmits the call to the
central station by bringing the line into connection with the earth. When said
switch B is in its normal position, a call sent from the central station sets in
operation a suitable notifying or signalling device A and a condenser C is
provided in series with the said equalling device which prevents the same being
operated by the ordinary call battery. Said condenser may be substituted by a
battery of diminutive size but of the same electro-motive force as the ordinary call
battery. M is a microphone of suitable resistance and sensitiveness fitted with its
membrane or diaphragm m³ and Te' is the earth or return wire.
Figure 4 is a diagram of the corresponding central station, the only difference
between it and the arrangement shown in Figure 2, Sheet I, being the addition of
a call-battery P³, one pole of which leads to earth at Te, and the other to the
extremities of all the subscribers' lines.
Figure 5 shows the alteration which should be made when it is desired to
substitute for the microphone batteries one single battery to operate a double wire
line or series of lines. It will be seen that this view represents nothing but the
parts involved in the said alteration, as it has been regarded as unnecessary here
to give a detailed representation of the calls, jacks and the like, in fact, any of the
special fittings which a double wire central station, such as that of Paris for
example, requires.
From P being the microphone battery, there extend two conductors R Q.
Along these conductors, the pairs of connecting cords C¹ c'. C' c³.... C₁ (ª are
arranged in parallel.. 1. L L L L L L designate the double
wire lines. d. d² . . . dª . D' . D'... Dª are respectively diagrams of complete
subscribers' or branch stations. The subscribers' stations are arranged in a manner
similar to that shown in Figures 1 and 3 except that a return wire Te¹ is taken to
the central station instead of going down to the earth on the subscriber's premises.
The operation is as follows:
Referring to Figures 1 and 2 the signalling or call devices of the branch stations
being exactly the same as those of the central station on certain well-known lines,
such as the Belgian lines, it is unnecessary further to dwell here on this feature.
The key or switch arrangement of the multiple board requiring no alteration

page_text: whatever, when It is desired to operate the signalling devices, we have not
represented it in detail in the drawings.
When the telephone clerk wants to communicate with the subscriber, he or she
inserts one of the pegs or plugs F into one of the "jacks" J, the other peg resting
with its base or bottom upon the table and forming the earth connection. The
key or switch being then properly turned on, the circuit of the station call
battery PI is closed through the clerks telephone and microphone T* M* and
through the cords and the pegs F F one of which forms the earth connection
through the table, while the other is connected with the line L L; and if the
telephone hook C happen to be raised at the subscriber's station, the current d
traverses the subscriber's microphone and telephone M' and T¹ and then proceeds
to earth e b and Te¹.
When the attendant at the central station wishes to place in communication two
subscribers, he gives the usual signals and places the pegs F F into the corresponding
"jacks" appertaining to the subscribers who are about to enter into conversation.
He then places the key upon the call device A' which is to announce the end of
the conversation, and within the circuit of which is comprised the microphone
battery P which is to actuate the microphones of the persons who are conversing,
through the medium of the pegs F F with their cords, and of the lines L.
During the conversation, the current passing through the call device A2 is not
sufficiently intense to cause the index-shutter to drop; but it acquires a sufficient
intensity for this purpose as soon as the customers hang up their receivers again
and give the handle the usual turn.
Referring to Figures 3 and 4. While at rest, the call battery P³ keeps all the
lines Land the condensers C¹ of the customers in the charged condition. When
either of the customers who are conversing presses this knob or button B, the
telephone being on its hook C, it will be seen that the connection of the line with
the condenser is cut off, the line being connected direct to the earth or to the
return wire. A derived current from the call battery will then pass through the
call device A', and cause the shutter to drop; and through the customers line
to earth.
The official at the central station, in order to call a subscriber, inserts one of the
pegs F into one of the customer's jack J, and then sends through the line a current
capable of operating a suitable call A at the subscriber's station.
The key or
switch arrangement of the multiple boards requires no alteration and is therefore
omitted from the drawing. The current employed may be either periodical,
undulatory, or of any other suitable nature, according to the type of apparatus A
used, and to the nature of the call (either phonic, sonorous, or other) which it is
desired to produce.
Should it be desired to place at the subscriber's station a small battery of equal
electro-motive force with, and in opposition to, the call battery, as a substitute
for the condenser just mentioned, this would involve no change so far as the
subscriber's station is concerned, as the connections would remain exactly the
same, though the call device A in this case may be an ordinary vibrating bell.
When the attendant at the central station wants to use the call device, it is only
necessary for him to increase the tension of the opposing battery.
The maintenance of such a small battery on the subscriber's premises would
occasion him no expense, since the battery would consume no extra current, its
charge being maintained in a uniform condition by the call battery arranged in
opposition, at the central station.
As regards the micro-telephonic connections, reference may be had to Figures 1
and 2 of the accompanying drawings in which they are fully illustrated.
By referring to Figure 5 and to what has been said before in reference to
Figures 1 to 4, the operation of the arrangement shown in Figure 5 will be readily
understood. The microphone battery P₁ is alone sufficient to feed the cord's
whereby two subscribers are placed in communication with each other or with the
ocal stations placed under the control of the officials of the company.

page_text: By examining the connections shown in Figure 5 it will also be seen that
whatever the number of subscribers which the microphone battery P is to supply
with current, there can arise no confusion in the communication.
In the case of town connections a double wire circuit serving for telephonic
purposes only is required.
If the subscriber's line be a double wire line, it is sufficient to branch it off
direct, without passing through the "translator," as in that case there is no
condenser to be met, or passed through, on the line.
If the subscriber's line be a single wire line a connection should be made through
the medium of a "translator."
Circuit serving simultaneously for telephony and telegraphy.
The circuits are connected as usual through the medium of a translator.
In the foregoing description no special microphone has been referred to in detail,
as I have found by experience that certain microphones, the proportions or dimensions
of which are well defined, when they are traversed by currents of sufficient tension,
will be found satisfactory enough when operating at great distances without the
use of an induction coil. But I may state that I have obtained the best results
that it has been possible to accomplish hitherto by the employment of a special
type of apparatus forming the subject matter of a separate Patent No. 7132
April 10th 1894. This being so I need not further describe it here.
I have hereinabove passed in review a number of particular cases likely to occur
in practice, in order to show with what facility iny improved arrangement is
applicable to each. It will be seen that my invention for all practical purpose-
remains the same, with the exception of certain alterations which the peculiar
circumstances of the case, or the special object in view, may demand.
It will of course be understood that I cannot possibly give a detailed description
of its application to all the different types of switchboard used at present, or which
may be used in times to come, in the different central telephone stations; but such
details as I have given will be sufficient to show that there is no case to which my
invention will not successfully apply, while the trifling alterations or modifications
which actual practice may demand in a given case will readily suggest themselves
to any skilled electrician.
I have only referred above. to currents generated by ordinary batteries, but it
will be obvious that ordinary batteries may easily be replaced by storage batteries
or other source of electricity.
The advantages arising from my improvements in telephone connections are as
follows:
1. No battery need be arranged on the subscriber's premises, and all the elements
in use may therefore be centralized, and kept under control, at one station; it
follows therefore that
(a) A considerable amount of labour is saved, as there is no occasion for the
maintenance of batteries and
(b) In offices or at stations where there are batteries fitted up, the necessary
conditions for insuring their durability and continuance in working order,
may be easily fulfilled.
2. The number of elements in use is considerably reduced.
In the case of single wire lines, at least four-fifths of the battery cells may be
dispensed with; while in the double wire lines, the number of cells may still further,
and to a very considerable extent, be reduced.
3. The amount of electrical energy expended is also very materially reduced.
Taking, for example, a double wire line in connection with my improved micro-
phone, may be sufficient to employ one microphone battery only supplying one
ampere at 15 volts to operate a series or network of telephone lines comprising
three thousand subscribers, assuming that it may be necessary at any moment to
place one-fifth of the total number of subscribers in communication with a second
fifth of that number at the same time.

page_text: 4. Satisfactory operation is much better ensured, inasmuch as
(a) Should a battery be defective, the telephone clerk is in a position imme-
diately to remedy the defect by changing the pair of cords;
(b) The microphones are not liable to be burnt (or if burnt at all, will be so to
a far less extent than hitherto) by the sparks produced in breaking circuits,
since the quantity of electrical energy passing through them is a great deal
less than that which passes through the microphones in use at the present
time.
5. The induction coil is dispensed with.
6. Such alterations as are necessary at the existing central stations, to work the
telephone on my improved system, may be made with great facility.
7. The subscribers or branch offices may be easily altered.
8. New stations, specially constructed with a view to the adoption of my
improved system, will be found less cumbersome and less expensive than stations
of the old arrangement.
9. The apparatus now in use may be replaced successively without any inter-
ruption in the performance of the usual work, as a new station, fitted up in
accordance with iny invention, will operate very satisfactorily in conjunction with
one of the old stations.
10. The distance at which telephonic communications may be exchanged is
considerably extended, as the resistance of a conductor is greater when it is
traversed by an alternate current than when it is by a continuous current.
11. No such powerful induction as alternate currents in an induction coil
necessitate need be used here, the current being direct.
.
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 :-
First. The employment of a battery interposed at the central station between
each pair of cords for the purpose of sending currents to the subscribers' stations
which are connected in position for conversation through the medium of pegs and
of the said cords attached to multiple or other switch boards; and dispensing with
the induction coil and the battery at the subscribers' stations, constructed in accord-
ance with my invention; it being possible to use existing stations simultaneously
with the new stations.
Second. In the case of a double wire line (or lines) in addition to sending the
current through a battery corresponding to each individual pair of cords, the
employment for one complete central station, of only one battery upon the con-
ductors of which the said pairs of cords are arranged in parallel.
Third. Dispensing, if necessary, with special batteries for feeding local or branch
stations (placed under the control of officials of the company) and substituting
therefor the current provided by or coming from the cords, the said branch stations
in that case operating exactly like the subscribers' stations.
Fourth. In the case of a call device being operated by means of a continuous
current, the employment of a battery arranged as the central station and adapted
to cause the index shutter corresponding to the line of the caller to drop; the
said battery being interposed between the extremities of all the customers' lines
and between the earth or return wires; such battery, being constantly kept charged,
and counterbalanced at the subscribers' station by a condenser or a local battery
of diminutive size but of the same electromotive force as the other battery.
Dated this 10th day of January 1895.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.