Improvements in Electric Fire Alarms.
Year: 1892

page_text: Date of Application, 27th June, 1392-Accepted, 3rd Sept., 1892
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COMPLETE SPECIFICATION.
Improvements in Electric Fire Alarms.
I, HARVEY CORTLAND, of 1, Rose Avenue, in the City of Toronto, in the
Province of Ontario, in the Dominion of Canada, Electrician, do hereby declare
the nature of my invention for "IMPROVEMENTS IN ELECTRIC FIRE ALARM AND,
CIRCUIT-CONTROLLING THERMOSTAT AND CLOCK MECHANISM," and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
My invention has reference to an automatic electric alarm, controlled by a
thermostat in such manner that when an excessive temperature occurs an alarm
will be sounded in the building, or at a central station, or both, and that if the
increase in temperature continues a second alarm will be sounded.
To this end combine with a thermostat adapted to first open and then close a
circuit as the temperature increases, circuits including alarms, and a clock mechanism
controlling the circuits, as presently to be explained.
In the accompanying drawings:-
Fig. 1, is a diagrammic illustration of my system of fire alarm.
Fig. 2, is a rear face view of one of the thermostats.
Fig. 3, is a cross section of the same, on line 3-3, and
Fig. 4, is an enlarged view of the switch-moving mechanism.
Referring to the drawings:-
A, represents the thermostat, of which there may be any suitable number,
consisting mainly of an annular metal ring or frame a, a concave disk a', of hard
rubber or analogous material seated firmly therein, a conducting finger a², sustained
at the middle by a screw a³, resting centrally on the concave side of the disk, and
two conducting fingers, and a. lying on opposite sides of the finger, a, and
connected in like manner with binding posts. The fingers a², and a', are normally
in contact so that the circuit is closed through them, but as the temperature rises,
and increases the concavity of the disk by expansion of the material, the finger a²,
is permitted first to separate from the finger, and open the original circuit, and
thereafter, as the heat continues, to contact with the finger a, and close the circuit
through a new channel. The two circuits thus controlled, will be hereinafter
referred to as the primary and secondary local circuits.
B, represents the main normally closed circuit connecting with the fingers a, a,
of the thermostat. This circuit includes the main battery B', and the relay C.
The relay in turn controls a normally open local circuit D, which includes first, a
local battery E; second, a local magnetic alarm bell F, of any ordinary construction,
intended to give a cautionary alarm; third, a central office instrument M, which
may be an alarm or annunciator, or both; fourth, the controlling magnet of a spring
actuated mechanical switch and signalling instrument L, and its switch proper
hereinafter described in detail.
From the main circuit B, there is extended a normally open branch circuit G,
leading to the finger a, of the thermostat, and containing a relay H, which controls
a second normally open local circuit I.
3:
This last named circuit contains first, the magnetic alarm bell K, to indicate the
existence of a fire; second, the battery E, and third, the magnet of the before
mentioned instrument L, and its switch /.
This secondary local circuit is open both at the switch, and at the thermostat.
The instrument L, contains a rotary signal wheel P, located in a circuit Q, which
includes a central office instrument R, which may be of any construction adapted
to be operated electrically, for example, an ordinary annunciator or alarm bell.
This circuit to the central office may be arranged independently of the other

page_text: circuits, as shown, or connected with them in any suitable manner, the one require-
ment being that the operation-of the instrument L, shall transmit a definite or
distinctive signal to the central station.
One central office instrument may be connected with any desired number of
circuits, each serving to transmit its individual or distinctive signal to the office.
The operation of the system is as follows:-
The main circuit B, is closed at the thermostat through the fingers, a², and a',
so that the relay C, holds the local circuit D, open. When the temperature rises
above the predetermined limit, the separation of the fingers a², and a', opens the
main circuit B, whereupon the relay C, permits the closing of the local circuit D,
which is followed by the sounding of the cautionary alarm F, and by the starting
of the switch and signal instrument L, through the action of its magnet l. The
instrument L, transmits a signal to the central office instrument and at the same
time shifts the switch, so as to open the local circuit D, and prevent the wastage
of the battery E. The switch continuing its movement, closes a second local
circuit I, which is, however, held open in the meantime at the relay H. If the
temperature continues to rise, as it will do in the event of a fire occurring in its
vicinity, the fingers a², and a³, will close the main circuit through its branch G,
thereby causing the relay H, to close the secondary local circuit I, which is followed
by the sounding of the local fire alarm K, and by the operation of the instrument L,
and the transmission of the signal thereby to the central office, the reception of
this second signal at the office will at once be recognized as an indication of fire.
I will now describe in detail the construction of the instrument L.
A frame 2, contains an ordinary clock train and its actuating spring. This
train carries a signalling wheel, having on its periphery a series of teeth or
insulated portions, co-operating, with a conducting finger 1, after the manner of
ordinary signalling instruments now in use, to transmit the signal to the central
station. The shaft which carries the signal wheel also carries an eccentric 16, which
acts on an overlying lever, from which a rod 18, is extended downward to one
end of the angular switch finger P. As the eccentric revolves, it lifts the lever
and shifts the switch to open the 'primary local circuit and close the secondary
local circuit, as before described.
After the sounding of the second or fire alarm, the switch is restored to its
normal condition by hand. The starting and stopping of the instrument L, is
effected by a detent lever S, such as is commonly used in striking clocks, this lever
being provided with an armature, in the field of the electro-magnet before referred
to. Whenever the magnet attracts the lever in consequence of the closing of
either of the local circuits, the eccentric and signal wheel are permitted to make a
single revolution.
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 combination with the double acting thermostat, the main spring and branch
circuits controlled thereby; the relays in said circuits; the local circuits controlled
by the relays and containing alarm instruments, and a 'switch mechanism controlled
by one local circuit and acting to open the same and to close the other.
2. In combination with the double acting thermostat, the main and branch
circuits, their relays, the local circuits controlled by the relays and containing alarm
instruments, and the mechanical alarm switch mechanism or instrument L, adapted
to open one local circuit and close the other, and also adapted and arranged to
transmit a signal to a central office instruinent, and a magnet to control the
instrument L, located in the local circuit.
.
3. The improved thermostat, consisting of the frame, the convex expansible
disk, the conducting fingers aª, and a', and the intermediate conducting finger a²,
operated by the disk.
4. In an alarm mechanism, the combination of a double acting thermostat and

page_text: two circuits controlled by the thermostat, and each controlling an independent.
alarm.
5. In combination with a thermostat, and two circuits controlled thereby, the
mechanical switch instrument L, consisting of the spring actuated clock train and
its eccentric, the lever moved by the eccentric and connected to the switch proper,
and the controlling magnet.
6. The combined switch and signal instrument, consisting of the spring actuated
clock train, the signal wheel and finger, the eccentric, the lever actuated thereby,
the switch proper connected with the lever, the detent, and the magnet controlling
the detent.
Dated this 6th day of L. 1000
HARVEY CORTLAND.