Improvement in Automatic Fire Alarm Systems.
Year: 1891

page_text: Date of Application, 25th Aug., 1891
Complete Specification Left, 28th Jan., 1892-Accepted, 25th June, 1892
PROVISIONAL SPECIFICATION.
Improvement in Automatic Fire Alarm Systems.
I, GILMAN WELD BROWN, of West Newbury, in the County of Essex and
State of Massachusetts, United States of America, Gentleman, do hereby declare
the nature of this invention to be as follows:-
This invention in automatic fire alarm systems has for its object to provide a
novel system, whereby the sounding of false alarms is obviated and the system
rendered more reliable in case of fire.
In accordance with my invention one or more thermostats constructed as will be
described and located in a building or structure to be protected, are included in a
normally closed circuit supplied with current from a battery or other suitable
source of electricity, and provided at a main or central station with a receiving
instrument, consisting essentially of an audible signal controlled by the polarized
armature of an electro-magnet.
The thermostat referred to is constructed, so as to produce reversals of the
current over the main line and thereby operate the electro-magnet to sound the
audible signal in case of fire. The receiving instrument, preferably, also comprises
a visual indicating instrument by which the condition of the line circuit may be
made known to the operator or attendant at the fire station or central office.
The polarized armature of the electro-magnet is preferably adjusted so as to be
withdrawn from its electro-magnet when the strength of the current flowing over
the line falls below the normal, as, for instance, in case of a weakening of the
battery, a short-circuiting of the line, or a dead break in the line, the withdrawal
of the armature operating the audible signal to call the attention of the operator
at the central office to the fact that a change in the condition of the main line has
taken place.
The visual indicating device referred to is preferably provided with a scale
suitably marked to indicate a weakening of the battery, a broken line or a fire,
whereby the attendant upon hearing the alarm may sec at a glance under what
condition the line circuit is placed.
My invention in an automatic fire alarm system therefore, consists in the com-
bination of a main line circuit and an electro-magnet provided with a polarized
armature of a pole changing thermostat located in the line to operate.
The
The receiving instrument of my improved automatic fire alarm system consists
essentially of an audible signal, which preferably comprises an electro mechanically
operated gong or bell, of any usual or well known construction having a striker
on arm secured to a shaft having a crank arm joined by a connecting rod to a
pivoted arm provided with a detent cooperating with a detent on a lever or arm
also having at its upper end a detent with which co-operates another detent on a
pivoted armature carrying lever and provided with an armature for an electro-
magnet suitably supported within the case of the receiving instrument.
pivoted arm is rotated in the usual manner, as by a system of gears or clockwork
actuated by a normally wound spring or it may be by a weight. The armature of
the electro-magnet is preferably composed of hardened steel, and polarized or
made a permanent magnet and, under normal conditions, the polarity of the electro-
magnet is such as to attract the armature and place the detent on the pivoted
armature lever in the path of movement of the detent on the arm and thereby
hold the striker on the arm away from the gong or bell.
In accordance with my invention, the polarized armature of the electro-magnet
is repelled from the poles of the magnet by a reversal in the current flowing over
the line in which the electro-magnet is located. The reversal of the current is

page_text: effected by means of a pole changing thermostat.
This thermostat consists
essentially of a block or supporting base of insulating material, usually wood,
porcelain or hard rubber, and provided on one face with two springs formed of flat
strips of metal, constituting one set of pole changing arms for the thermostat.
These springs are firmly secured to the base at one end they being bent down
over the rear side of the block and the said strips have secured to them binding
screws to which the line wires are secured.
The free ends of the strips are normally secured by a fusible material or solder,
such as an alloy of lead, tin, cadmium or the like, to conducting strips secured to
the front side of the block or supporting base. The conducting strips have
secured to them binding screws by which the line wires may be connected with the
thermostat. The spring strips have secured to them on their under sides pro-
jecting, pole-changing arms constituting the other set of pole-changing arms for
the thermostat. The pole-changing arms project into a recess or cavity in the
base and co-operate with the circuit terminals extending across the said recesses.
The pole changing arms are provided with fingers, which extend under the circuit
terminals when the thermostatic springs are in their normal condition but which
are adapted to be brought up into contact with the circuit terminals when the
thermostatic springs are released by the melting of the solder or fusible connection,
as in the case of a fire.
In the normal condition of the system, the thermostatic springs are secured to
the contact strips by the fusible connection, and the armature is attracted by its
magnet. the current flowing over the line in what may be termed the normal
direction.
If now the thermostat should be operated, as by the breaking out of a fire in its
vicinity, the thermostatic springs being released by the melting of the fusible
connections, would fly upward and thus bring the pole changing arms into contact
with the circuit terminals when the current would pass to the receiving instrument,
and through the electro-magnet in a reverse direction, and thence out over the
line again to the negative pole of the battery.
By the reversal of the current over the main line, as thus described the gong or
bell is sounded thus giving an alarm at the receiving instrument that a change in
the condition of the circuit has been effected.
In order that the operator at the central office may positively know whether the
alarm thus sounded is due to the operation of the thermostat or to a broken wire
or for other cause, an indicating device, preferably visual, is employed which may
be located within the case. The indicating device, consists of a galvanometer
coil having pivotally suspended within it a polarized needle preferably of hardened
steel, mounted on a shaft or arbor within the coil, said arbor having secured to it
a pointer which co-operates with the plate or dial secured in a suitable manner
to the framework of the case. The dial is provided with four graduations or
indications marked respectively "OK" battery run down line broken and "fire."
The attendant at the main office, by glancing at the dial, can ascertain from the
pointer the fact that the battery has been weakened, but in order to render this
feature more positive, I prefer that the alarm or audible signal should also be
sounded when the battery is thus weakened. This may be accomplished by
adjusting the tension of the retractor for the armature which retractor may consist
of a spiral spring. When the battery has been weakened, the spring will with-
draw the armature from its electro-magnet and release the motor mechanism and
sound the alarm.
In case of the broken wire, the current will cease flowing over the main line,
and the pointer will fall to zero or to the indication marked "broken line 80 also,
if the main line should be short circuited the same effect would be accomplished
auu, in either case the armature would be withdrawn by its spring to start the
motor and operate the alarm.
In the normal condition of the main line the pointer stands at the indication "OK,”
but when the thermostat is operated, as by the breaking out of a fire, the current

page_text: is reversed, and the pointer will pass beyond the zero position to the other side
toward the indication marked "fire." In this way the operator at the fire or
receiving station is enabled to know positively for what cause the alarm has been
sounded; or in other words, the true condition of the line circuit at all times is
made known to him so that in case of any accidents of the line circuit, the same
may be readily repaired without rendering the circuit inoperative for any consider-
able length of time.
In practice it might happen that the current would be reversed by the operation
of one thermostat, the alarm sounded and the pointer deflected to the indication
marked "fire," and immediately after a second thermostat might be operated and
the current again reversed and the current restored to its normal direction, thus
restoring the parts of the receiving instrument to their normal condition.
So
In order that the operator may know positively whether the alarm is due to a
fire I have provided a detent or catch for the pointer the said detent or catch being
located near the "fire" indication and adapted to engage the pointer when the
latter has been moved to the "fire" indication by the reversal of the current.
also I prefer that the polarized armature should be withdrawn by its spring when
repelled from its magnet, sufficiently far to remove it from the influence of its
magnet thus requiring that the said armature be replaced in operative position by
the operator.
Dated this 12th day of Anavat AD 1201
GILMAN WELD BROWN.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvement in Automatic Fire Alarm Systems.
I, GILMAN WELD BROWN, of West Newbury, in the County of Essex, and
State of Massachusetts, United States of America, Gentleman, 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 :-
This invention in automatic fire alarm systems has for its object to provide a
novel system, as will be described, whereby the sounding of false alarms is obviated,
and the system rendered more reliable in case of fire.
In accordance with my invention, one or more thermostats constructed as will be
described and located in a building or structure to be protected, are included in a
normally closed circuit supplied with current from a battery, or other suitable source
of electricity, and provided at a main or central station with a receiving instrument
consisting essentially of an audible signal controlled by the polarized armature of
an electro-magnet.
The thermostat referred to is constructed, as will be described, so as to produce
reversals of the current over the main line and thereby operate the electro-magnet
to the sound of the audible signal in case of a fire. The receiving instrument, pre-
ferably, also comprises a visual indicating instrument by which the condition of the
line circuit may be made known to the operator or attendant at the fire station or
central office.
The polarized armature of the electro-magnet is preferably adjusted so as to be
withdrawn from its electro-magnet when the strength of the current flowing over
the line falls below the normal as, for instance, in case of a weakening of the
battery, a short circuiting of the line, or a dead break in the line, the withdrawal
of the armature operating the audible signal to call the attention of the operator at
the central office to the fact that a change in the condition of the main line has
taken place.
The visual indicating device referred to is preferably provided with a scale

page_text: suitably marked to indicate a weakening of the battery, a broken line or a fire,
whereby the attendant upon hearing the alarm may see at a glance under what
condition the line circuit is placed.
My invention in an automatic fire alarm system therefore, consists in the com-
bination of a main line circuit and an electro magnet provided with a polarized
armature, of a pole changing thermostat located in the line to operate substantially
as will be described.
The particular features of my invention will be pointed out in the claims at the
end of this Specification..
Figure 1 is an elevation of the receiving instrument employed on an automatic
fire alarm system embodying my invention.
Fig. 2 is a sectional detail on an enlarged scale of the upper portion of the
receiving instrument, the section being taken on the line 2, 2.
Fig. 3, a top or plan view of a thermostat embodying my invention, the thermostat
being shown in operative condition.
Fig. 4, a longitudinal section of the thermostat shown in Fig. 3 on line 4, 4.
Fig. 5, an under side view of the thermostat shown in Fig. 3.
Fig. 6, a longitudinal section of the thermostat shown in Fig. 3 on line 4, 4,
showing the thermostat as having been operated.
Fig. 7 is a diagram of circuits, showing two thermostats as connected to the
receiving instrument, only a portion of the case of which is shown, the thermostats
being in their operative positions ready to send in an alarm of fire: and
Fig. 8, a diagram of circuits showing the thermostats connected to the operative
parts of the receiving instrument, the thermostats being shown as having been
operated by a fire.
The receiving instrument of my improved automatic fire alarm system consists
essentially of an audible signal, shown as an electro-mechanically operated gong or
bell, of any usual or well known construction, it consisting of a striker on an arm a
secured to a shaft a', having the crank arm a² joined by a connecting rod a³ to a
pivoted arma provided with a detent a' co-operating with a detent on a lever or
arm a, having at its upper end a detent a', shown in dotted lines in Fig. 1, with
which co-operates a detent a³ on an armature carrying lever a, pivoted as at a
and provided with an armature a¹² for an electro magnet als, suitably supported
within the case a" of the receiving instrument. The pivoted arm a is rotated in
the usual manner, as herein shown, by a system of gears or clockwork as actuated
by a normally wound up spring a¹, or it may be by a weight. The armature a
of the electro magnet is preferably composed of hardened steel, and polarized or
made a permanent magnet and, under normal conditions, the polarity of the electro-
magnet a¹³ is such as to attract the annature a¹ and place the detent as on the
armature lever uº in the path of movement of the detent a' on the arm a, and
thereby prevent the movement of the pivoted arm a', and consequently hold the
striker on the arm a away from the gong or bell A.
In accordance with my invention, the polarized armature a¹ of the electro-
magnet is repelled away from the poles of the magnet a¹³ by a reversal in the
current flowing over the line in which the electro-magnet a¹³ is located. The
reversal of the current is effected by means of a pole changing thermostat, preferably
constructed as shown in Figures 3 to 6 inclusive. The thermostat consists essen-
tially of a block or supporting base 6 of insulating material, usually wood, porcelain
or hard rubber, and provided on one face with two springs 2, shown as flat
strips of metal, constituting one set of pole changing arms for the thermostat.
These springs are firmly secured to the base b at one end, they being herein shown
as bent down over the rear side of the block b; and the said strips have secured
to them binding screws b³ respectively, to which the line wires are secured, as
will be described.
The free ends of the strips 612 are normally secured by a fusible material or
solder, such as an alloy of lead, tin, cadmium, etc., to conducting strips 66 66, shown
in Figures 3 to 6 inclusive, as secured to the front side of the block or supporting

page_text: base. The conducting strips º º, as herein shown, have secured to them binding
screws 68 by which the line wires may be connected with the thermostat. The
spring strips have secured to them on their under sides projecting, pole-changing
arms 10, constituting the other set of pole-changing arms for the thermostat,
one of the said arms being shown in full lines, Figures 4 and 6, and both of which
are indicated by dotted lines in Fig. 5. The pole-changing arms 10 project into
a recess or cavity in the base b, and co-operate with the circuit terminals herein
shown as rods or bars 13614 extending across the said recesses.
The circuit terminal 618 is connected by a conducting wire to the binding
screw, and the circuit terminal 61 is connected by conducting wire 61 to the
binding screw, as clearly shown in Fig. 5. The pole-changing arms 66,10, as
herein shown, are provided with fingers, which extend under the circuit
terminals 13 when the thermostatic springs bare in their normal condition
shown in Figures 3 and 4; but which are adapted to be brought up into
contact with the circuit terminals 13 when the thermostatic springs are released
by the melting of the solder or fusible connection, as in the case of a fire.
This position of the thermostatic springs is indicated in Fig. 6. In the normal
condition of the system, the thermostatic springs are secured to the contact
strips by the fusible connection, and the armature a is attracted by its
magnet al, the current flowing over the line in what may be termed the normal
direction, as indicated by the arrows 20 in Fig. 7.
If now the thermostat should be operated, as by the breaking out of a fire in
its vicinity, the thermostatic springs, being released by the melting of the
fusible connection, would fly upward and thus bring the pole-changing arms 10
into contact with the circuit terminals 134, in which case the current would
flow over the line, as indicated in Fig. 8, it passing from the positive pole of
the battery B in the direction indicated by arrow 20, until it came to the
spring and the connection between the spring 2 and its co-operating strip 6
being interrupted, the current will flow down the pole-changing arm, as indicated
by arrow 21, and by the circuit terminal and wire 16 to the binding
screw, from whence it would pass into the receiving instrument, and through
the electro-magnet as in a reverse direction, and thence out over the line again
to the binding screw 8, from whence it would pass by the conducting wire 1,15
and terminal 13 to the pole-changing arm, and thence by the spring
the negative pole of the battery.
to
By the reversal of the current over the main line, as thus described, the polarized
armature a is repelled by its magnet a¹³, and the armature lever is turned on
its pivot a so as to withdraw the detent from engagement with the detent a
on the lever a, and thereby permit the spring or motor a" to turn the pivoted
arm a and the striker arm a and sound the gong or bell A, thus giving an alarm
at the receiving instrument that a change in the condition of the circuit has been
effected.
In order that the operator at the central office may positively know whether the
alarm thus sounded is due to the operation of the thermostat or to a broken wire or
for other cause, an indicating device, preferably visual, is employed which may be,
and preferably is, located within the case a. The indicating device, as herein
shown, consists of a galvanometer coil e, having pivotally suspended within it a
polarized needle c' preferably of hardened steel, mounted on a shaft or arbor c
within the coil c, said arbor having secured to it a pointer c³ which co-operates with
the plate or dial e secured in a suitable manner to the framework of the case. The
dial, as herein shown (see Fig. 1) is provided with four graduations or indications
marked respectively "OK," battery run down," "line broken," and "fire," the
"line broken" indication occupying a central or zero position on the scale.
66
If the galvanometer coil is not being traversed by an electric current, the
pointer would stand on the zero position or "line broken" indication, and when
the current is traversing the coil in its normal direction, the pointer will be
turned to one side of the zero position, as for instance to the left, as shown in

page_text: Fig. 1, and when the current is reversed as has been described, the pointer will be
deflected to the indication marked "fire."
The attendant at the main office, by glancing at the dial, might ascertain from
the pointer the fact that the battery had been weakened; but in order to render
this feature more positive, I prefer that the alarm or audible signal a should also
be sounded when the battery is thus weakened. This may be accomplished by
adjusting the tension of the retractor for the armature a¹, which retractor is herein
shown as a spiral spring d. When the battery has been weakened, the spring d¹
will withdraw the armature 12 from its electro-magnet and release the motor
mechanism and sound the alarm A. In case of a broken wire, the current will
cease flowing over the main line, and the pointer will fall to zero or to the
indication marked "broken line." So also, if the main line should be short circuited,
the same effect would be accomplished and, in either case, the armature a¹ would
be withdrawn by its spring d¹ to start the motor and operate the alarm.
In the normal condition of the main line the pointer e stands at the indi-
cation "OK," but when the thermostat is operated, as by the breaking out of a
fire, the current is reversed and the pointer c will pass beyond the zero position to
the other side toward the indication marked "fire." In this way the operator at
the fire or receiving station is enabled to know positively for what cause the alarm
has been sounded; or, in other words, the true condition of the line circuit at all
times is made known to him, so that in case of any accidents of the line circuit, the
same may be readily repaired without rendering the circuit inoperative for any
considerable length of time.
Referring now to Figures 7 and 8, the current in the normal condition of the
circuit, as indicated in Fig. 8 by arrow 20, passes through the galvanometer and
electro-magnet back over the line wires; whereas when the thermostat is operated
and the polarity reversed, the current passes through the electro-magnet and
galvanometer, back over the line.
In practice it might happen that the current would be reversed by the operation
of one thermostat, the alarm sounded and the pointer c³ deflected to the indication
marked "fire," and immediately after a second thermostat might be operated and
the current again reversed and the current restored to its normal direction, thus
restoring the parts of the receiving instrument to their normal condition.
In order that the operator may know positively whether the alarm is due to a
fire, I have provided a detent or catch e (see Figures 1 and 2) for the pointer c³,
the said detent or catch being located near the "fire" indication and adapted to
engage the pointer when the latter has been moved to the "fire" indication by
the reversal of the current. So also I prefer that the polarized armature should be
withdrawn by its spring, when repelled from its magnet, sufficiently far to
remove it from the influence of its magnet, thus requiring that the said armature
be replaced in operative position by the operator.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1. In an automatic fire alarm system, the combination with a main line circuit,
an electro-magnet located therein and provided with a polarized armature, and a
receiving instrument controlled in its operation by the said polarized armature, of a
pole changing thermostat located in the main line circuit and consisting of two sets
of pole changing arms, one set being normally connected in the main line by a
fusible connection, and the other set being norinally not included in the said
circuit but adapted to be included in the said circuit by the melting of the fusible
connection, to re-establish the main line with reversed polarity after the said line
has been opened by the operation of the fusible connection, substantially as
described.
2. In an automatic fire alarm system, the combination with a main line circuit,
an electro-magnet located therein and provided with a polarized armature, and an

page_text: audible signal controlled in its operation by the said polarized armature, of a pole
changing thermostat located in the main line circuit and consisting of two sets of
pole changing arms, one set being normally connected in the main line by a fusible
connection, and the other set being normally not included in the said circuit but
adapted to be included in the said circuit by the melting of the fusible connection,
to re-establish the main line with reversed polarity after the said line has been
opened by the operation of the fusible connection, substantially as described.
3. In an automatic fire alarm system, the combination of the following
instrumentalities, viz.: a main line circuit, an electro-magnet located in said circuit
and provided with a polarized armature, a visual indicating device included in the
main line circuit, and a pole changing thermostat adapted to be operated by
increase in temperature to reverse the polarity of the main line and operate the
visual indicator reversely, substantially as described.
4. In an automatic fire alarm system, the combination of the following
instrumentalities, viz.: a main line circuit, an electro-magnet located therein, an
audible signal controlled by the said electro-magnet, a visual indicating device
operated by changes in condition of the circuit, and a pole changing thermostat,
substantially as described.
5. A pole changing thermostat having two sets of pole changing arms, one set
consisting of conducting springs held in tension by fusible solder and in position to
conduct the current in one direction, the other set of pole changing arms being
connected to the said springs and normally not included in the line circuit but
which are included therein by the operation of the said springs to reverse the line
current when said springs are released, substantially as described.
6. The herein described pole changing thermostat, consisting of a base, conducting
springs secured thereto at one end and provided with pole changing arms,
conductors on said base, fusible connections joining the said conducting springs to
the said conductors, and circuit terminals with which the pole changing arms
co-operate when the said springs are released by the melting of the fusible
connections, to re-establish the said circuit and reverse the polarity of the same,
substantially as described.
Dated this 17th day of December 1891
GILMAN WELD BROWN.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.