Improvements in Electric Fire Alarms.
Year: 1895

page_text: Date of Application, 1st Aug., 1895
Complete Specification Left, 1st June, 1896-Accepted, 1st Aug., 1896
PROVISIONAL SPECIFICATION.
Improvements in Electric Fire Alarms.
We ALFRED CHARLES BROWN of 129 Algernon Road Lewisham in the County
of London Electrician and GEORGE RICHARD NEILSON of 96 New Park Road
Clapham Park in the County of London Secretary to Public Company do hereby
declare the nature of this invention to be as follows:-
In the ordinary street fire alarm telegraphs it is found very essential that calls
coining from the posts or call points shall produce at the station a signal which is
very decidedly distinguishable from the effects of any contacts or other faults that
may happen to or on the line wire. To do this more definitely than heretofore is
one of the objects of the present invention.
For this purpose we place in the street or other post or wall box a rapid make
and break or "buzzer "adapted to be operated electrically on either the breaking
of the glass, opening of the door, or pulling or pushing of a knob or button at
option, and arranged thenceforth rapidly to make and break an electrical circuit so
as to produce a rapidly intermittent or pulsatory current which actuating a
telephone, or electromagnet opposed to a diaphragm at the station causes a loud
noise to be made therein, which serves as a fire (or other) call instead of a bell,
with the advantage that such sound is certain never to be produced by a fault on
the wire or wires. Or instead of the intermittent or pulsatory current being
received on a telephone the rate of the make and break in the call point may be
somewhat lower and the current received upon the electromagnet of a single stroke
bell at the station which is thereby caused to act as a trembling or continuous
ringing bell when operated by current that has gone out through the make and
break in the call point but which will only give a single stroke when the line is put
in contact or to earth.
The curient to operate the above arrangement may be supplied by a battery or
magneto or dynamo placed either at the fire station or at the call point or otherwise
and where the rapid rate make and break and telephone is used, the current which
operates the receiver may be either the direct current that has passed through the
make and break instrument itself or may be induced or transformed therefrom. In
the posts or wall box, and in either series or parallel circuit, with the coils of the
make and break instrument we prefer to place also a loud-speaking telephone
receiver having preferably a funnel mouthpiece opening into the post head or else
toward louvred openings in the containing case, or this telephone receiver may also
itself form the rapid make and break for the buzzer call, by having a contact screw
arranged to make contact at its point with the diaphragm from which it is otherwise
insulated at its attachments the screw and diaphragm being then included in series
in circuit with the coils of the receiver. We also place in the cail point a trans-
mitter preferably adapted to work on direct circuit by current that has come out
from the station to avoid the necessity of batteries in the street. But if desired a
local cell or cells and induction coil may be applied in the ordinary way and the
contacts to complete the circuit through them may be actuated by the same
mechanism as puts the current from the buzzer to line.
At the fire station we also provide a loud-speaking telephone transmitter preferably
with induction coil, and telephone receiver and to which instruments the line can be

page_text: switched by a two way switch attached to each wire, which switch operates to divert
the current either on to these speaking instruments or to the ordinary indicator
drop coil and sounder receiver, or single stroke bell, as above described on which it
stands normally.
We also arrange to enable a return call to be given from the station to the call
point at any time over a single line where such only is used with an earth return
and without requiring any batteries or other generators at the post for sending the
call from there to the station.
To do this we place in the station a buzzer or rapid make and break and a key to
switch same into circuit together with a current generator, and either directly into the
line circuit or preferably into circuit with the primary circuit of an induction coil the
secondary circuit of which is connected between the call point line and earth or
return. Or the extra currents from an electro-magnet which may be the one
operating the "buzzer " or make and break instrument itself may be diverted by
the key into the line circuit.
The intermittent current thus produced runs down the line and through the coils
of the telephone receiver at the call point (a condenser being then used at the post
to bridge across the call contact so as to enable the return call to be sent from the
station to the post when the line circuit is disconnected thereat in consequence of
the call contact not being closed the capacity of the condenser permitting plenty
of undulatory current to pass in and out to operate the call but the insulation
between the plates giving the necessary disconnection to prevent the flow of the
battery current) and into and out of a small condenser which we place in circuit
between the telephone coils and earth, and which condenser therefore forms a
complete disconnection in the circuit to prevent the running of the current from
the battery or generator the potential of which we keep constantly on the line from
the station for other purposes but permits the free movement of the undulatory
current through the telephone coils (by charging and discharging) so as to make a
loud sound to call.
Or instead of using an induction coil or electromagnet to generate extra currents
at the station we may send an undulatory or reversed pulsatory current direct to
line and may then receive same at the post either on the telephone or on a magneto
(or other rapidly acting single stroke) bell mechanism capable of being operated by
the short but rapid currents running into and out of the condenser.
Where a metallic circuit is used however we may dispense with the condenser for
the return call by placing our telephone receiver or bell at the call point between
any point of the line directly incoming from the station, and earth, and our
generator at station between same line and earth, the connection there being taken
off preferably at a point before the circuit has passed through any other instru-
ments, the whole of the resistance of which, required for other purposes, are kept
in the metallic circuit.
Or conversely when a metallic circuit is used, we may work our return call (from
station to call point) in the metallic circuit, and cause the fire alarm call (from call
point to station) to be operated between the metallic circuit and earth.
Dated this First day of August 1895.
A. C. BROWN,
Electrician.
GEO. R. NEILSON,
Secretary to Public Company..

page_text: ALFRED CHARLES BROWN of 129 Algernon Road Lewisham in the County of
London Electrician and GEORGE RICHARD NEILSON of 96 New Park Road
Clapham Park in the County of London, Secretary to Public Company 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 :-
In the ordinary street fire alarm telegraph it is found very essential that calls
coming from the posts or call points shall produce at the station a signal which is
very decidedly distinguishable from the effects of any contacts or other faults that
may happen to or on the line wire. To do this more definitely than heretofore is one
of the objects of the present invention.
For this purpose we place in the street or other post or wall box a rapid make
and break or "buzzer "adapted to be operated electrically on either the breaking
of the glass, opening of the door, or pulling or pushing of a knob or button at
option, and arranged thenceforth rapidly to make and break an electrical circuit so
as to produce a rapidly intermittent or pulsatory current which actuating a
telephone, or electro-magnet opposed to a diaphragm at the station causes a loud
noise to be made therein, which serves as a fire (or other) call instead of a bell,
with the advantage that such sound is certain never to be produced by a fault on
the wire or wires.
The current to operate the above arrangement may be supplied by a battery or
magneto or dynamo placed either at the fire station or at the call point or otherwise,
and the current which operates the receiver may be either the direct current that
has passed through the make and break instrument itself or has been induced or
transformed therefrom. In the post or wall box, and in either series or parallel
circuit, with the coils of the make and break instrument we prefer to place also a
loud-speaking telephone receiver having preferably a funnel mouthpiece opening
into the post-head or else towards louvred openings in the containing case, or this
telephone receiver may also itself form the rapid make and break for the buzzer
call, by having a contact screw arranged to make contact at its point with the
diaphragm from which it is otherwise insulated at its attachments, the screw and
diaphragm being then included in series in circuit with the coils of the receiver.
We also place in the call point a transmitter preferably adapted to work on direct
circuit by current that has come out from the station to avoid the necessity of
batteries in the street. But if desired a local cell or cells and induction coil may
be applied in the ordinary way and the contacts to complete the circuit through
them may be actuated by the same mechanism as completes the line circuit through
the buzzer.
At the fire station we also provide a loud-speaking telephone transmitter preferably
with induction coil, and telephone receiver and to which instruments the line can
be switched by a two way switch attached to each wire, which switch operates to
divert the circuit either on to these speaking instruments or to the ordinary indicator
diop coil and sounder receiver, as above described and on which it normally stands.
We also arrange to enable a return call to be given from the station to the call
point at any time over a single line where such only is used, with an earth return,
and without requiring any batteries or other generators at the post, for sending the
call froin there to the station.
To do this we place in the station a buzzer or rapid make and break, and a
key to switch same into circuit together with a current generator, and either
directly into the line circuit or preferably into circuit with the primary circuit of

page_text: an induction coil the secondary circuit of which is connected between the call
point line and earth or return. Or the extra currents from an electro-magnet
which may be the one operating the "
"
"' buzzer or make and break instrument itself
may be diverted by the key into the line circuit.
The intermittent current thus produced runs down the line and through the coils
of the telephone receiver at the call point (a condenser being then used at the post
to bridge across the call contact so as to enable the return call to be sent from the
station to the post when the line circuit is disconnected thereat in consequence of
the call contact not being closed, the capacity of the condenser permitting the
undulatory current to operate the call, but the insulation between the plates giving
the necessary disconnection to prevent the flow of the battery current).
Or instead of using an induction coil or electro-magnet to generate extra currents
at the station we may send an undulatory or reversed pulsatory current direct to
line and may then receive same at the post either on the telephone or on a magneto
(or other rapidly acting single stroke) bell mechanism capable of being operated
by the short but rapid currents running into and out of the condenser.
Where a metallic circuit is used however we may dispense with the condenser
for the return call by placing our telephone receiver or bell at the call point
between any point of the line directly incoming from the station, and earth, and
our generator at station between same line and earth, the connection there being
taken off preferably at a point before the circuit has passed through any other
instruments, the whole of the resistances of which, (required for other purposes)
are kept in the metallic circuit.
Or conversely when a metallic circuit is used, we may work our return call
(from station to call point) in the metallic circuit, and cause the fire alarm call
(from call point to station) to be operated between the metallic circuit and earth.
In working out our invention we find it also very desirable to give the buzzer or
rapid make and break armature a knock off mechanically in order to ensure its
starting in presence of a little irregularity and also provide a second contact lever
to come into action on the opening of the door of the call point, post or wall box,
and complete the circuit to earth or return without passing through the rapid
make and break, so as to give the station a signal to attend to telephone, without
constituting a fire call.
DESCRIPTION OF DRAWINGS.
Figs. 1 & 2 of the accompanying diawings are respectively a front elevation and
section through vertical centre line of the complete apparatus which we prefer to
use in the "call point" or street post or wall box, although the details may be
considerably varied. Fig. 3 is a smaller scale cross section of receiver only without
magnet, on line x x of Fig. 2. Similar letters apply to both. A is a base board
on which is mounted a telephone receiver, B, preferably of the Collier type as
shown. C. & D are bell crauk-shaped levers rotating independently on a common
spindle P fixed in lugs F F1 cast on part of the receiver frame as shown. Each of
these levers are separately pulled over in one direction by the tensile spiral
springs G G¹. The lever C carries at one end a contact screw H which makes
contact with a platinised contact on one of the diaphragms of the receiver when
the lever is pulled home by the spring so that the contact screw end thereof abuts
on the faced seating on the side of the receiver case as shown more clearly
in Fig. 3. The cranked end C¹ of lever C is normally held down by a stud
bearing on the giass front of the door of the street post, wall box, or other
containing case, (the said stud preferably sliding through a grid metallic backing
for the glass) so that when in this position the contact screw H is held out of
contact with the diaphragm of the receiver. The cranked end of the becond
lever D is also held back when the door of the post or wall box is closed by the
adjustable and insulating screw J, pressing on the back of the grid behind the
glass, but which pressure is released on the door being opened, thus allowing

page_text: the lever to spring forward and bringing the wire contact K into contact with
stud O but which contact is normally open. M is a telephone transmitter
preferably of the form described in Patent Specification No. 4021 of February 24th,
1894, and which is preferably shunted by a wire resistance of about 50 ohms,
indicated by N, to prevent damage from the heavy direct currents sometimes used
on the fire alarm. The electrical connections and action of the apparatus are as
follows. At the fire station is a battery with one end joined to earth or return
line, and the other to line through the coils of an indicator drop motion (for
showing which line calls), and a loud telephone receiver preferably of the Collier
form and having a cone over its mouthpiece. The line from the fire station then
connects to the lefthand terminal L of the call point instruments. From here the
circuit extends to the casting F F which when the door is closed and glass
unbroken is insulated from everything, so that the circuit is then disconnected at
this point. When the glass is broken however the cranked end C¹ of contact
lever C is released and flies out by the action of the spring G thus bringing the
contact screw H sharply up into contact with the diaphragm I Fig. 3 of receiver,
and the centre of which diaphragm is loaded with a little additional weight so that
on receiving this knock the diaphragm is thrown into vibration mechanically
independently of the electro-magnetic action which is also simultaneously com-
menced. This diaphragm connects electrically with stud O and thence to one side
of the receiver coils the other side of which connects to terminal R. From here
the circuit extends on through the telephone transmitter and the wire shunt across
same to terminal E which connects to earth or the return wire to station. On the
glass being broken therefore a rapid make and break is efficiently started and
maintained between diaphragm I and contact screw H which causes a loud buzzing
sound both at the call point and in the receiver at fire station, which constitutes a
fire call not capable of being imitated by the effects of any contact or other
accident likely to happen to the line. The fireman at station then by means of an
ordinary telephone jack plug switch or other ordinary well understood arrange-
ment switches the line circuit off the station battery (thus stopping the buzzing
sound) and on to and through an ordinary telephone speaking set, preferably
having also a powerful form of transmitter as described above, by means of which
the fireman is enabled to speak to the caller at post through receiver B so loudly
as to enable him to hear without applying the telephone to his car, altering any
switches, or doing anything requiring technical knowledge. A few cells of battery
are also included in the line circuit with the speaking set at station, not enough
the continue the sound of the buzzer, but sufficient to energise the direct-current-
transmitter M at call point, by means of which the fireman at station having
receiving-telephones to his ears is enabled to hear the callers' replies, and send the
engine direct to the fire. On the door of the post being opened without the glass
being broken however, the lever D comes up as well as C, which has the effect of
short circuiting the make and break contact (as will be seen on tracing the
connections,) thus dropping the indicator (and if desired also ringing a bell) at
station to call attention to telephone, as for use for ambulance purposes etc., but
without sounding the buzzer and thus giving a fire call.
A condenser indicated by S may also be placed across the normal open gap in
the circuit so as to provide that if a rapid intermittent current (as produced by an
induction coil &c.) be sent from the station to the post the receiver at the latter
will be caused to sound loudly at any time whether the contacts of levers C & D
be closed or open, thus constituting an effectual call from station to call point
available at any time, without the disadvantage of keeping current running, the
latter being prevented by the insulation between the plates of the condenser.
Instead of causing the lever C to spring up on the glass being broken a handle
may be applied to the former or its equivalent, and be required to be pulled up by
hand in addition to breaking the glass or opening the door, in order to give the
fire call, if desired by the officials in charge.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a fire alarm telegraph the use and employment in combination with each
other for the purpose of a fire signal, of an electromagnet and a rapidly vibrating
armature and contact placed at the call point, and operated by current that has
come out from the station through an ordinary drop indicator, and an electro-magnet
having an opposed diaphragm capable of responding to the current impulses
produced by the rapid make and break at the call point, as and for the purposes
above described.
2. The method described above of efficiently starting the rapid make and break
armature by giving it a knock mechanically simultaneously with the completion of
the electric circuit therethrough.
3. At a fire alarm call point the use of two contact levers one to complete the
circuit through and mechanically start a rapid make and break instrument, or
current intermitter, and the other to short circuit the rapid make and break
contact, or to complete the line circuit in such way that the current passes through
the rest of the apparatus to earth or return line but is diverted from the said make
and break contact, whether such contact levers are moved automatically or arranged
to be operated by hand.
4. The use for the purposes mentioned in Claim 3 of two automatic contact
levers, the one acting on the breaking of the glass, and the other as well as
the first on the opening of the door, to fulfil the objects enumerated above.
5. The combination with each other of the various mechanical parts and electrical
connections described above and illustrated in the accompanying drawings.
Dated this Thirtieth day of May 1896.
A. C. BROWN.
GEO. R. NEILSON.