Improvements in Fire Alarms.
Year: 1898

page_text: Date of Application, 8th Feb., 1898-Accepted, 19th Mar., 1898
Improvements in Fire Alarms.
I, WILLIAM ANDERSON GUTHRIE, of Durham, in the County of Durham, and State
of North Carolina, 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:-.
Fig. 1 is a perspective view, showing my invention in use.
Fig. 2 is a front elevation, with the cap removed.
Fig. 3 is a cross sectional view.
Fig. 4 is a perspective view.
This invention relates to an automatic fire alarm, and the object thereof is to
provide a simple device, which, should a fire occur in the room where it is located,
will be operated by the increased temperature, establish an electric circuit and ring an
alarm bell or indicate in any other desired manner, the presence of the fire.
With the above object in view, the invention consists of a casing which may be
attached to the wall or ceiling of the room, and having a metal plate to which one of
the wires of the circuit is attached; a spring plate to which the other wire is con-
nected, and which is normally held out of contact with the first named plate
by a screw-threaded rod extending through a plate of fusible metal and receiving
a nut.
"
The invention also consists in certain novel features of construction, and in com-
binations and arrangements of parts hereinafter fully described and afterwards
specifically pointed out in the appended claims.
Referring to the accompanying drawing, A indicates the 'base which is screw-
threaded to receive the cup A¹ which is contracted at its outer end and formed'
on the interior thereof adjacent said end, with the annular shoulder a. The
base may be secured to the ceiling or wall by screws or other securing
devices.
་
B is a metal plate secured to the inner side of the base by the screws b, to which
is attached one of the wires C of an electric circuit, in which is located an alarm bell
or other indicating device, the other wire C of the circuit being connected to one of
the screws, c, which secure the spring plate B¹ to the base. When this spring plate
makes contact with plate B, the circuit is established and the bell or indicating
device operated.
For holding the spring plate normally out of engagement with the plate B and the
circuit broken, I provide the rod E, screw-threaded at its outer end and formed with
a hook at its inner end to engage an eye carried by the spring plate. The outer
screw-threaded end of this rod extends through a plate F of fusible metal and
receives a nut E¹. Said plate of fusible metal engages the annular shoulder of the
cup, and as the nut is adjusted upon the rod, the spring plate is drawn out of contact
with plate B and held in that position.
Should a fire occur in the room, the metal plate will fuse and release the rod which
will permit the spring plate to return to its normal position, engaging plate B and
establishing the circuit, ringing the alarm bell or operating the indicating device and
viving warning of the fire.

page_text: By operating the nut by the hand, the alarm could also be sounded, as will be
readily understood.
From the above description, it will be seen that I have produced a very
simple construction of automatic fire alarm, which is positive and reliable in its
operation.
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 :-
1. In a device of the character described, the combination of the contact plates,
and a fusible metal retainer for holding the plates out of contact, substantially as
described.
2. In a device of the character described, the combination with the contact plates,
of a fusible metal plate, and a connection between the fusible plate and one of the
contact plates, whereby the latter are held out of contact, substantially as
described.
3. In a device of the character described, the combination with the contact plates,
-of a fusible metal plate, and an adjustable connection between said fusible plate and
. one of the contact plates, whereby the latter are held out of contact, substantially as
--described.
4. In a device of the character described, the combination with the contact plates,
of a fusible metal plate, a rod attached to one of said plates and to the fusible
plate and adapted to hold the contact plates out of engagement, substantially as
-described.
5. In a device of the character described, the combination with the contact plates,
of a fusible metal plate, and a rod attached at one end to one of the contact plates
and screw-threaded at its opposite end, said screw-threaded end passing through the
fusible plate and receiving a nut, substantially as described.
$
6. In a device of the character described, the combination of a contact plate, a
second spring contact plate adapted to engage the first plate, and means for holding
said spring plate out of engagement with the other contact plate, but adapted to
automatically release the same when the temperature has reached a certain point,
substantially as described.
7. The combination with a base, a cup carried thereby and provided with an
annular interior shoulder, contact plates carried by the base, a rod attached to one of
said contact plates and screw-threaded at its opposite end, and a fusible metal plate
engaging the annular shoulder of the cup and through which the screw-threaded
end of the rod extends and receives a nut, substantially as described.
Dated this 8th day of February 1898.