Improvements in or relating to Automatic Electric Fire Alarms.
Year: 1892

page_text: Date of Application, 30th Mar., 1892
Complete Specification Left, 1st Apr., 1892-Accepted, 4th June, 1892
PROVISIONAL SPECIFICATION.
Improvements in or relating to Automatic Electric Fire Alarms.
I, LEONIDAS GORHAM WOOLLEY, of Grand Rapids, in the County of Kent,
in the State of Michigan, United States of America, Inventor, do hereby declore
the nature of this invention to be as follows:-
:-
The object of my invention is to produce an automatic electric fire alarm con-
structed to suddenly and automatically separate a magnet and armature, one of
which is provided with an induction coil, when the temperature of the room or
building in which it is placed has reached any prescribed degree, whereby a
momentary current is produced in the induction coil, for sounding an alarm at a
central station or other place through line wires connected therewith, thus doing
away with a battery and electric contacts so liable to be out of order when a fire
occurs, and avoiding the defects of an ordinary electric fire alarm.
An arrangement of fire alarm according to this invention is as follows:-
To an L-shaped bracket or support fixed within a room or building at any
desired point, but preferably to the ceiling, is secured a depending permanent
magnet preferably of the horse shoe type, which has two poles or arms of unequal
length, or it may be of equal length, as will appear further on.
Upon one arm of the magnet is placed an induction coil which has its opposite
ends connected with line wires connected with an electric indicator of any desired
construction, which is placed at a central station, or other place where it is
desired to sound an alarm. The magnet armature is held to the poles of
the magnet by magnetism, and is L-shaped to extend to the long and short ends
thereof.
A lever is pivoted near the inner ends to a depending arm of the said bracket.
The long end of this lever engages a notch made in the upper end of a thermostatic
bar while a weight is suspended upon the short end thereof.
This thermostatic bar is composed of dissimilar metals, the expansion of one
being greater than that of the other so that if the temperature of the room or
building is raised, the said bar will bend. This bar is set so that when the tem-
perature of the room or building has reached a prescribed degree, it will have bent
sufficiently at its upper end to disengage the notch thereof from the end of the
said lever, which allows the weight to drop.
A chain connects the weight and armature so that the dropping of the weight
suddenly removes the armature from the magnet, thus producing a momentary
current by induction in the coil which sounds an electric alarm to be connected
therewith. The armature is connected with the bracket by means of another
chain which prevents it and the weight from becoming detached from the device
when they drop.
By making one end of the magnet longer than the other, the coil can be wound
thereon by placing the magnet in a lathe, thus reducing the cost of winding the
magnet, while at the same time the inner coils of the induction coil can be wound
tightly thereon, thus intensifying the current over that produced when the coil is
wound and then slipped thereon. When the two arms of the magnet are of the
same length, the coils must be first wound and then slipped thereon, or if wound
directly thereon must be wound by hand, thus increasing its cost.
In a modified arrangement the releasing device consists of a fusible hook upon
which the weight is suspended. When the temperature has been raised sufficiently
to fuse the hook, the weight drops and causes a current in the manner hereinbefore
described.
In another arrangement there is a pivoted armature and a magnet, the arms of

page_text: which are of the same length, though one arm may be shorter than the other and
the armature correspondingly shaped, if desired. There is also provided a spring
actuated lever which is held set by means of a fusible block placed between the
free end of the lever and the pin; or this pin itself may be made fusible. In this
case when the block or pin is fused, the spring actuated lever will be released. and
strike the free end of the armature thereby moving it suddenly from the poles of
the magnet and creating a momentary current in the induction coils.
Another modification of the releasing device consists of a glass ball filled with
gases which will explode and burst the ball when the temperature of the room or
building has reached a certain degree, thus releasing the spring lever for striking
the armature and moving it from the magnet.
From the above description it will be seen that I do not limit myself to any
particular kind of magnet releasing device, or means for suddenly releasing the
armature, for any one or all of these may be varied to any desired degree, without
departing from the spirit of my invention, which comprises a magnet having an
armature, a stored up power for suddenly releasing it, and a thermostatic trip
device for suddenly removing the power.
By means of an alarm of this character, all danger of its becoming inoperative
from inattention, corroding or oxidizing or the lapse of time is entirely overcome,
as will be understood, thus producing a simple and cheap fire alarm without the
serious defects usually attending devices of this character.
I make the induction coil of very fine wire, whereby a current of very high
electro-motor force is obtained as compared with that of the current produced by a
battery.
For instance I can use a wire so fine that a momentary current of high voltage
is obtained, to produce which by a battery would require a great number of
cells.
The induction coil or helix has its terminals permanently connected to a suitable
electro-magnet in a signalling apparatus. The purpose of the electro-magnet is
simply to momentarily release an armature or tripping device in a large mechanical
gong, actuated by weights or springs, as the current generated by a single sudden
removal of the armature from the magnetic poles is but momentary, and too feeble
to directly operate a bell striker. It will now be understood that the coil or helix
of insulated wire to be brought under the influence of the permanent magnet by
the sudden removal of its armature, is placed in a permanently closed circuit with
the signalling apparatus, the current necessary to operate the entire system being
produced wholly by induction from a permanent magnet thus all circuit closing
devices and batteries are entirely dispensed with.
Owing to this fact I am enabled to use smaller conductors than can be used with
a battery, and at the same time produce a more certain result with a corresponding
lessening of expense.
Although I have stated that the induction coil or coils is or are placed upon the
magnetic poles, the said coil or coils may be placed upon the armature and the
same result produced.
So also in either case, the armature may be permanently held, and the
magnet itself suddenly removed therefrom the result being nearly the same.
Dated this 30th day of March .1892.

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Automatic Electric Fire Alarms.
I, LEONIDAS Gorham Woolley, of Grand Rapids, in the County of Kent, in
the State of Michigan, United States of America, Inventor, do hereby declare
the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement:-
The object of my invention is to produce an automatic electric fire alarm con-
structed to suddenly and automatically separate a magnet and armature, one of
which is provided with an induction coil, when the temperature of the room or
building in which it is placed has reached any prescribed degree, whereby a
momentary current is produced in the induction coil, for sounding an alarm at a
central station or other place through line wires connected therewith, thus doing
away with a battery and electric contacts so liable to be out of order when a fire
occurs, and avoiding the defects of an ordinary electric fire alarm.
In the drawings,
Fig. 1 is a side elevation of a fire alarm which embodies my invention complete.
Figs. 2 and 3 are similar views showing modifications.
Fig. 4 is a detached view showing a modification of the destructible or fusible
device.
Fig. 5 is a view of a modified form showing the armature stationary, and magnet.
removable.
A indicates an L-shaped bracket or support which is secured within a room or
building at any desired point, but preferably to the ceiling. Secured to this bracket
and depending therefrom is a permanent magnet B, preferably of the horse shoe
type, which has two poles or arms of unequal length, the arm C, being here shown
the longer, though this specific construction can be reversed if desired, or the arms
made of equal length, as will appear further on.
Where the magnet is formed as shown in Fig. 1, an induction coil L is placed on
the longer arm C, which has its opposite ends connected with line wires connected
with an electric indicator of any desired construction, which is placed at a central
station, or other place where it is desired to sound an alarm. The armature E is
held to the poles of the magnet by magnetism, and is L-shaped to extend to the
long and short ends thereof.
A lever I, is pivoted near the inner ends to a depending arm H, of the bracket A.
The long end of this lever engages a notch made in the upper end of a thermostatic
bar J, while a weight G is suspended upon the short end thereof.
This thermostatic bar is composed of dissimilar metals, the expansion of one being
greater than that of the other so that if the temperature of the room or building is
raised, the bar J bends in the direction indicated by arrow. This bar is set so that
when the temperature of the room or building has reached a prescribed degree, it
will have bent sufficiently at its upper end to disengage the notch thereof from
the end of the lever 1, which allows the weight to drop as shown in dotted lines.
A chain F connects the weight and armature E, so that the dropping of the weight
suddenly removes the armature from the magnet, thus producing a momentary current
by induction in the coil L, which sounds an electric alarm to be connected therewith.
The armature E is connected with the bracket by means of a chain F, which prevents
it and the weight from becoming detached from the device when they drop.
By making one end of the magnet longer than the other, the coil L can be wound
thereon by placing the magnet in a lathe, thus reducing the cost of winding the
magnet, while at the same time the inner coils of the induction coil can be wound
tightly thereon, thus intensifying the current over that produced when the coil is
wound and then slipped thereon. When the two arms of the magnet are of the

page_text: same length, the coils must be first wound and then slipped thereon, or if wound
directly thereon must be wound by hand, thus increasing its cost.
In Fig. 2 I show a modified form of releasing device which consists of a fusible
hook M, upon which the weight is suspended when the temperature has raised
sufficiently to fuse the hook, the weight drops and causes a current in the same
manner as shown in Figure 1.
In Figure 3, I show a pivoted armature E', and a magnet B₁, the arms of which
are of the same length, though one arm may be shorter than the other, and the
armature correspondingly shaped, if desired. I here show a spring actuated lever
which is held set by means of a fusible block placed between its free end and a
pin d, or the pin d itself may be made fusible. In this case when the block or pin
is fused the spring actuated lever is released, which strikes the free end of the
armature moving it suddenly from the poles of the magnet creating a momentary
current in the induction coils L¹.
Another modification of the releasing device is shown in Figure 4, which
consists of a glass ball which is filled with gases which will explode the ball
when the temperature of the room or building has reached a certain degree,
thus releasing the spring lever a for striking the armature and moving it from
the magnet.
From the above description it will be seen that I do not limit myself to any
particular kind of magnet releasing device, or means for suddenly releasing the
armature, for any one or all of these may be varied to any desired degree,
without departing from the spirit of my invention, which comprises a magnet
having an armature, a stored up power for suddenly releasing it, and a thermo-
static trip for suddenly removing the power.
By means of an alarm of this character, all danger of its becoming inoperative
from inattention, corroding or oxidising or the lapse of time is entirely over-
come, as will be understood, thus producing a simple and cheap fire alarm
without the serious defects usually attending devices of this character.
I make the induction coil of very fine wire, whereby a current of very high
electro-motor force is obtained, over that compared with the current produced by a
battery.
For instance I can use a wire so fine that a momentary current of high voltage
is obtained, to produce which by a battery would require a great number of
cells.
The induction coil or helix has its terniinals permanently connected to a
suitable electro-magnet in a signalling apparatus. The purpose of the electro-
magnet being simply to momentarily release an armature or tripping device in
a large mechanical gong, actuated by weights or springs, as the current
generated by a single sudden removal of the armature from the magnetic poles
is but momentary and too feeble to directly operate a bell striker. It will now
be understood that the coil or helix of insulated wire to be brought under
influence of the permanent magnet by the sudden removal of its armature, is
placed in a permanently closed circuit with the signalling apparatus, the current
necessary to operate the entire system being produced wholly by induction from
a permanent magnet, all circuit closing devices and batteries are entirely
dispensed with.
Owing to this fact I am enabled to use smaller conductors than can be used with
a battery, and at the same time produce a surer result with a corresponding lessening
of expense.
While I here show the induction coil or coils placed upon the magnetic poles it
may be placed upon the armature as shown in Figure 5, and the same result
produced.
So also in either case, the armature may be permanently held, and the magnet
itself suddenly removed therefrom, as shown in Figure 5, the result being nearly
the cama

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. An automatic electric fire alarm comprising a permanent magnet, an armature
therefor, an induction coil, a stored power for suddenly separating the armature
and magnet, and a thermostatic releasing device, substantially as specified.
2. An automatic electric fire alarm comprising a permanent magnet, an
armature therefor, an induction coil or helix in a permanently closed circuit
with a signalling apparatus, a. stored power for suddenly separating the armature
and magnet, and a thermostatic releasing device, substantially as set forth.
3. An automatic electric fire alarm comprising a permanent magnet, an
armature therefor, an induction coil, a means for suddenly separating the
armature and magnet, to produce a momentary current in the coil, and a thermo-
static holding and releasing device holding the means until the temperature
effects it sufficiently to release it, substantially as specified.
4. An electric fire alarm comprising a permanent magnet, an armature therefor,
an induction coil, a weight connected with the armature, and a thermostatic
device for holding and releasing the weight, substantially as set forth.
5. An automatic electric fire alarm comprising a magnet carrying a coil, an
armature therefor, a weight connected with the armature, a pivoted lever
supporting the weight, and a thermostatic device for holding and releasing the
lever, substantially as specified.
6. An automatic electric fire alarm comprising a magnet carrying an induction
coil, an armature therefor, a weight connected with the armature, a pivoted
lever supporting the weight, and a strip composed of dissimilar metals having
one end permanently held and its opposite free end engaging the said lever,
whereby heated temperature expands the metals unevenly and releases the lever
to allow the weight to suddenly remove the armature, substantially as specified.
Dated this 1st day of April 1892.
L. G. WOOLLEY,
By L. W., per F. B.