Improvements in Electric Fire Alarms.
Year: 1895

page_text: Date of Application, 10th Sept., 1895-Accepted, 12th Oct., 1895
COMPLETE SPECIFICATION.
Improvements in Electric Fire Alarms.
We, CHARLES DARWIN TISDALE, of 124 Trenton Street East Boston, Boston,
Suffolk County, State of Massachusetts Electrician, and JOHN DUNKLEE GOULD,
of 399 Flatbush Avenue, Brooklyn, County of Kings, State of New York, Broker,
both in the United States of America, do hereby declare the nature of this inven-
tion, and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
The object of the present invention is to provide a simple, cheap and efficient
electrical thermostat or electrical fire alarm system for use more particularly in
apartment houses dwellings, buildings and the like, although also applicable to
stores warehouses, factories and the like, and the invention consists in combination
with a room or other apartment or place, of a tube of any suitable material, and
constructed and located in the room or other place, of mercury or other suitable
heat expanding liquid material within the tube, an electric circuit, and a sounding
device all constructed and arranged for operation substantially as hereinafter fully
described.
The said invention is illustrated in the accompanying drawing in which
Figure 1 is a detail perspective view of two walls of a room with this invention
applied thereto;
Figure 2 is a longitudinal section of the tube and connecting parts;
Figure 3 is a diagram of the electric circuit.
In the drawings A, B, represents in detail two sides of a room in a house, and
C the mop or skirting board.
As shown in the drawings on one side of the room along the mop or skirting
board is a tube D, preferably of metal and of small diameter, and at one end it is
bent upward and its end E secured in the bottom of a vertical tube F preferably of
larger diameter.
Within this vertical tube F is a glass tube G, and secured therein by cement a,
and adapted to screw on to the upper end of the vertical tube is a cap H, the
central portion of which is filled with an insulating material J which extends
through a central opening in the head of the cap H.
Over the other end of the tube D is secured by a screw thread the end of another
metal tube K preferably of larger diameter and on this tube K is screwed another
tube or long cap L.
Within the chamber d of the tube K is a plunger or piston M adapted to move
to and fro therein, having a central rod e extending along the cap tube L and
projecting through a central opening fin its end, and on the end of this rod are two
Hanges g, h, one g, of which is inside the tube and bears against the inside of the
end cap, and the other h, of which bears against the outside holding the rod e to
the cap L but allowing free turning of the cap thereon.
The tube cap L is arranged to screw to and fro on the tube K, and in its
movements it carries with it the piston M along the tube chamber d.
P is a vertical tube or spout having a flaring mouth m, to be closed by a stopper n.
Mercury N is poured into the spout, which flows into the chamber d, between the
plunger M and tube D and along the tube D, and up the glass tube G, the plunger
being moved in or out to adjust the height of the mercury in the glass tube to the
temperature of the room at the time.
A longitudinal slit t is made in the front of the metal tube F over the glass

page_text: tube G, so that the glass tube and the mercury therein can be seen, and along this
slit is a scale of degrees u for instance Fahrenheit, and it is preferably arranged
for the mercury in the glass tube G to indicate in the usual manner of thermometers
the degrees of heat in the room, although any suitable scale, can be used.
Extending down through the insulating material J into the glass tube G is a
metal wire which is arranged to be moved up and down therein as desired.
This wire and the mercury in the tube are connected electrically with an
electric battery as follows:
From the wire Q extends an electric wire R to an armature S pivoted at
to a support and from this extends a wire T which connects with an electro
magnet U.
From the electro magnet runs another wire V to the mechanism of a bell W
and from this mechanism runs another wire Y to one pole of an electric
battery A'.
From the pole of the electric battery extends a wire B¹ which connects with the
cap H of the vertical tube F or it can connect with the tube D at any place, so it
can make an electric connection with the mercury therein.
a
Connected to the wire B' is a wire C connected to a metal plate D' having
point w, which as shown is a little distance below the electro magnet U, this point w,
projecting beyond the vertical plane of the end a' of the magnet, so that if the
armature S is drawn toward the magnet it being of suitable length it will bear upon
the plate D' but not touch the end of the magnet at a' as shown by the dotted lines
in Figure 3.
With a room having this system of electrical fire alarm located therein, and
connected to any suitable sounding device at any place desired, the wire Q is moved
up in the glass tube, until its lower end is at the degree of the scale representing
the heat at which the alarm is to be given, which may be at 150 or 200 or any other
desired degree.
Now if a fire occurs in any room, the tube at such place becomes heated, which
communicates heat to the mercury therein and causes it to expand sufficiently to
rise in the glass tube until it touches the end of the wire Q; instantly owing to the
contact of the two, the electric circuit is completed causing the bell to sound,
giving warning of the fire in the room where this device is placed, at the same time
the electromagnet attracts the armature S until it bears and rests upon the plate D'
which short circuits the electric current, by completing the circuit from the plate
through the battery, bell, magnet and armature, which circuit will then be
maintained, continuously sounding the bell.
The object of this short circuit is to keep the bell sounding as long as possible
to ensure warning being given to the person desired, as for instance, without this
arrangement of short circuit, it, from one cause or another the mercury after it
had made contact aud the electric circuit as described should drop from its contact
with the wire, thus breaking the electric circuit, the sounding of the bell or alarm
would cease, which would often fail to accomplish the result desired, for if the
person who it was intended should be notified of the fire, should at that particular
time be away, he would not hear the alarm; but with the continuous sounding of
the bell by the maintaining of the short circuit through the plate the person would
be sure to be notified sooner or later.
The tube D can be very small in diameter in order not to use much mercury,
and to take up little room; as shown it is only on one side of the room, it can
extend away round the room, along the mop or skirting board or at any desired
place and height in the room, for instance, when near the floor can be disposed in
one of the hollows or grooves of the molding of the mop or skirting board, and
can be ornamented as desired; the vertical tube and glass tube can be arranged
in any part of the room desired, also the battery can be in any suitable place in
or out of the room; the bell however is preferably arranged to be in some other
room, or outside the room, or corridor, or on the outside of the building or in any
other building or room.

page_text: The great advantage of this system of electrical fire alarm, is that, the tube
with the mercury can extend round the room indefinitely, and into all places
connected therewith, making what might be called a continuous tubular electric
thermostat, so that the instant, flame or extreme and dangerous heat touches or
warms up any part of the continuous tube, the mercury therein immediately expands,
which forces up its column in the glass tube into contact with the terminal or
electrode wire Q making the electric circuit, and giving the alarm which by the
means of the electro magnet and the short circuiting of the electric current continues
to sound the bell until some person is notified. By this arrangement of the tube
so extensively around the room or other place an alarm will be given immediately
at the start of the fire and before it becomes dangerous or of any magnitude, which
obviously is very important.
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 an electric fire alarm device, a tube extending along and around the side
or sides of a room or other place, an upward extension of said tube, a wire connected
with one pole of an electric battery arranged in said tube extension insulated
therefrom a chamber at the other end of said first tube, a plunger or piston
therein, operated from the outside, and mercury in said tubes and chamber and
connected electrically with the other pole of the electric battery.
2. In an electric fire alarm device, a tube extending along and around the side
or sides of a room or other place, an upward extension of said tube, a glass tube
within said extension, a cap screwing on to said tube extension having insulating
material therein, a wire extending through the insulating material and into the
glass tube connected with one pole of an electric battery, and mercury in said
first tube and glass tube connected electrically with the other pole of the electric
battery.
3. In an electric fire alarm device, a tube arranged along and around the side or
sides of a room or other place, an upward extension of said tube, a wire connected
with one pole of an electric battery, arranged in said tube extension insulated
therefrom, mercury in said tube, connected electrically with the other pole of the
electric battery, a tube of larger diameter secured to the other end of said first
tube, a chamber therein, a cap screwing on to the end of said latter tube, a plunger
or piston in said chamber, a rod extending from said plunger out through the
head of said cap and connected thereto by flanges on said rod.
Dated this 10th day of September 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.