Detonating Fire Alarm.
Year: 1886

page_text: Date of Application, 3rd July, 1886.
Complete Left, 4th Apr., 1887.
Complete Accepted, 14th June, 1887.
Detonating Fire Alarm.
I, CARL JOHANN DAVID OPPERMANN of 55 Spencer Street Clerkenwell London
Engineer, do hereby declare, the nature of my invention for A DETONATING FIRE
ALARM to be as follows:-
This invention consists of the most inexpensive means for causing an explosion
when the temperature exceeds normal limits or a certain number of degrees. A
weight carrying a detonator, which may be a percussion cap, or a detonator of
sufficient weight to explode when striking the ground is suspended by means of a
substance or composition of suitable melting point, or indirectly by means of string,
wire, cotton or other suitable means at a sufficient distance from the ground. The
string, wire or cotton consists of pieces held together directly or indirectly by a
substance or composition of low melting point which flows or runs at a temperature
produced by, or preceeding an outbreak of fire. The detonator or weight carrying a
detonator may be suspended in such a manner, that a piece of compound metal,
consisting of metals of different expansion and contraction, like the compensation
balance, by altering its shape in an increased temperature dislodges the detonator and
allows it to strike the ground or other piece of resistance.

page_text: I, CARL JOHANN DAVID OPPERMANN of 55 Spencer Street Clerkenwell London,
Electrical Engineer do hereby declare the nature of my invention for A DETONATING
FIRE ALARM and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This invention supplies simple means for causing an explosion when the temperature
increases beyond limits of safety, and is to be used in dwellings, factories, warehouses
or other places used for storage to call attention to increased temperature or to the
danger of an outbreak of fire at the earliest possible moment.
A weight of suitable shape to which a detonator is attached, by preference a
percussion cap, or a detonator which explodes when striking the ground is suspended
at such a height above the floor, that when being released it will receive sufficient
impetus in falling to cause an explosion when striking the ground.
The weight or detonator is suspended either by means of a pair of metal discs stuck
together with stearine, paraffin wax, ozokerit, wax or a composition of these or any
others of the well known materials from which candles are made, and which have a
suitable melting point, or by means of string, wire or cotton thread, the ends of which
are held together by the above described materials or compositions. The most
suitable temperature at which the weight or detonator is to drop is about 100 degrees
and the material or composition used should be perfectly fluid at a somewhat higher
temperature, because the strain of the suspended weight will make it give at from
5 to 10 degrees below it's state of perfect fluidity. It is necessary to try carefully the
melting-point of each parcel of material before using it, as the exact melting point
cannot be relied upon, although the stuff may be obtained from the same source as
some bought previously.
When desirable the plate to be protected may contain only the discs or other parts
held together by the material or composition of low melting-point, a string or thin
wire connecting them to the weight or detonator which may be suspended at
considerable distance therefrom in a more suitable or central position.
A very convenient form of weight and disc, plan and section of which are shown,
is represented in the drawing, although the shape may be varied endlessly, and I do
not bind myself to this or the use of any particular shape. The weight A is pear-
shaped and has a nipple or projection below on which a percussion-cap fits. The
discs are of sheet metal or other suitable material and shaped as shown at B, and
being dished form a small pan in which a portion of the previously mentioned material
or composition can be conveniently molten and another similar pan being placed

page_text: inside, they form when cold a pan with two handles which separates at an increased
temperature. By mixing materials of lowest and highest melting-point in different
proportions, compositions of every melting-point required can be obtained.
The suspended weight may also be used, when released by increased temperature,
to move a semaphore or signal, or to start an alarm by electrical or mechanical means
in any well known manner.
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. The suspending of a detonator or weight with a detonator attached for the
purpose described.
2. The use of stearine, paraffin wax, ozokerit, wax, spermacety, sperm, composite,
yellow wax, or a composition of these and similar materials substantially as and for
the purpose described.
3. The use of a detonator or weight with a detonator attached to call attention to
increased temperature or the possible outbreak of fire substantially as described.
4. The use of a suspended weight, which when released by increased temperature
moves a signal or semaphore or starts an alarm bell mechanically or by forming
electric contact.