IMPROVEMENTS IN AUTOMATIC FIRE ALARMS
Year: 1877

page_text: LETTERS PATENT to Frederick Bogen, of Valparaiso, at present residing at
10, London Wall, in the City of London, for the Invention of "IMPROVEMENTS
IN AUTOMATIC FIRE ALARMS." A communication from abroad by Charles
Albert Heinrich, of Leipzig, Saxony.
Sealed the 20th July 1877, and dated the 24th April 1877.
PROVISIONAL SPECIFICATION left by the said Frederick Bogen at the Office
of the Commissioners of Patents on the 24th April 1877.
FREDERICK BOGEN, of Valparaiso, at present residing at 10, London Wall, in the
City of London. "IMPROVEMENTS IN AUTOMATIC FIRE ALARMS." A communication
from abroad by Charles Albert Heinrich, of Leipzig, Saxony.
The object of this Invention is to provide an automatic fire alarm which shall be
able to give an immediate alarm in case of fire and before the fire has time to
increase to any material extent. For this purpose I employ two metallic coils, each
formed of two metallic strips united together, such as are sometimes used for moving
a pointer to indicate the temperature. One of the coils is enclosed within a thin
metallic case so as to be protected from currents of air, and consequently will not be
quickly affected by rapid changes of temperature. The other coil is on the exterior
of the case, and is made conical, so that the whole of it is freely exposed to the air
and is at once affected by changes of temperature. The inner end of this coil is
secured to a fixed stem, its outer end is free, and acts upon a crank arm carried by
an axis which passes into the interior of the case and through the centre of the coil
which is contained in this case.
The inner end of the coil within the case is carried by a fixed support, whilst its
outer end is free.
On the axis which passes into the case, as before mentioned, is an arm carrying a
metallic point. This point is ordinarily at a short distance from the end of the coil
within the case, but if any sudden rise in temperature takes place the outer coil,
being at once affected by the rise in temperature, moves the arm round and brings
it against the end of the coil. The contact may either be arranged to complete an
electric circuit and so set in action an alarm or alarms; or if the alarms are held out
of action so long as a current is passing, they may be caused to sound by the current
being diverted so soon as a contact is made in the manner described.

page_text: The alarm may also be caused to sound whenever the temperature rises steadily
and slowly beyond any given degree, by providing a stop for the outer end of the
enclosed coil to come against whenever the temperature has risen to the point fixed
upon, the revolving arm of the outer coil will then make contact as before described,
and the alarm will be sounded.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frederick Bogen in the Great Seal Patent Office on the 24th October
1877.
FREDERICK BOGEN, of Valparaiso, at present residing at 10, London Wall, in the
City of London. "IMPROVEMENTS IN AUTOMATIC FIRE ALARMS." A communication
from abroad by Charles Albert Heinrich, of Leipzig, Saxony.
The object of this Invention is to provide an automatic fire alarm which shall be
able to give an immediate alarm in case of fire and before the fire has time to
increase to any material extent. For this purpose I employ two metallic coils, each
formed of two metallic strips united together, such as are sometimes used for moving
a pointer to indicate the temperature. One of the coils is enclosed within a thin
metallic case so as to be protected from currents of air, and consequently will not be
quickly affected by rapid changes of temperature. The other coil is on the exterior
of the case, and is made conical, so that the whole of it is freely exposed to the air
and is at once affected by changes of temperature. The inner end of this coil is
secured to a fixed stem, its outer end is free, and acts upon a crank arm carried by
an axis which passes into the interior of the case and through the centre of the coil
which is contained in this case.
The inner end of the coil within the case is carried by a fixed support, whilst its
outer end is free.
On the axis which passes into the case, as before mentioned, is an arm carrying a
metallic point. This point is ordinarily at a short distance from the end of the coil
within the case, but if any sudden rise in temperature takes place the outer coil,
being at once affected by the rise in temperature, moves the arm round and brings
it against the end of the coil. This contact may either be arranged to complete an
electric circuit and so set in action an alarm or alarms; or if the alarms are held out
of action so long as a current is passing, they may be caused to sound by the current
being divorted so soon as a contact is made in the manner described.
The alarm may also be caused to sound whenever the temperature rises steadily
and slowly beyond any given degree, by providing a stop for the outer end of the
enclosed coil to come against whenever the temperature has risen to the point fixed
upon, the revolving arm of the outer coil will then make contact as before described,
and the alarm will be sounded.
Having thus described the nature of my Invention I will proceed to describe
more fully the manner of performing the same.
The Drawing hereunto annexed represents a self-regulating and self-acting fire
alarm, such as above described.
The instrument is intended to be suspended against the ceiling of an apartment,
and, when connected with a galvanic battery and an alarm bell, will, as above stated,
give immediate alarm in case of fire and before it has time to spread.
A, B, are two compound metallic springs; the spring B is enclosed by a box or
case D, whilst the spring A is on the exterior of this box; A is fastened by its
upper end to a brass stem t, t, which is secured to the lid of the box, and is coiled
into a conical shape so as to present a great surface to the current of heated air,
whereas B is bent into the form of a watch spring and is entirely enclosed; B is
suspended at its upper end by the arm p, which is soldered against the inner part of
the lid of the case D.

page_text: The axis x, isolated by means of the tube c, c, of horn or such like material,
passes through the centre of the case, and carries at its extremities two levers or
crank arms h and h¹.
8
The lower arm h is provided with a contact screw v, whereas the upper arm h¹
carries an ivory stem e, through which the lower end o¹ of the coil A freely moves.
Opposite to the contact screw and at some little distance from the coil end o is
a piece of copper wire s fastened against the inner side of the box. This pin serves
as a stop for the coil end o, and, by bending, can be adjusted to arrest the movement
of the coil end whenever any degree of temperature has been reached. Wires are
led from two connecting studs m and n (the first not being visible on the Drawing)
to the inside of the box. The wire from the stud m is led to the arm p, from which
the electric current passes to the end o of the coil B, and the wire from the stud n
is led to the isolated crank arm h and its contact screw v; ordinarily this contact
screw is at a short distance from the coil end o. Thus vand o become the two poles
of the battery.
As soon as a sudden rise of temperature takes place, the outer coil A, being at
once affected, moves the arms h and h¹ round and brings the metallic point v against
o, by which the electric circuit is closed and the alarm sounded. But whenever the
temperature rises slowly, as is caused by a stove fire, the burning of gas, the heat
produced by the sun, or the glowing heat, such as often preceeds the outbreak of a
fire, both coils A and B are expanded together in more or less the same ratio, and
the alarm will therefore not be given until o having reached the stop 8, the contact
screw can follow and make the contact with o. By this contrivance the apparatus
becomes a self-regulating and self-acting fire alarm, which, once adjusted, will serve
as effectually in cold as in warm climates without any further adjustment.
The instrument shown in the Drawing is on the open circuit principle, and can
be connected with electric bells where they are already in use without incurring any
material expense. But the same apparatus may be used on the principle of a closed
circuit by so arranging that the contact made between o and v shall divert the
current from the alarm instrument and so allow the bell to be sounded. This
arrangement presents great advantages inasmuch as any casual or intentional
breaking of the wire would at once be detected by the alarm being sounded. An
electro-magnet may advantageously be included in the circuit, and so arranged that
if the battery in time should get out of order or become weak, which may happen
after a twelvemonth's use, the armature will fall away from the magnet and a
circular plate maked "defect" will present itself.
The material which I employ for the springs or coils are strips of steel or iron
and nickel or German silver soldered together. To protect the iron or steel strips
from oxidizing they may be tinned or coated with a metal which is not liable
to rust.
It is obvious that the form of the apparatus may be changed without departing
from the Invention, as, for example, straight strips may be substituted for the coils,
or, instead of solid springs and coils, hollow ones may likewise be used, either a void
or filled with liquid to increase the sensibility of expansion.
But what I claim is, the construction of automatic fire alarms with two coils or
strips, the one exposed and the other to some extent protected, and so arranged that
a sudden rise of temperature determines an electric contact by causing a more rapid
change of form in the exposed coil or strip than in the other.
In witness whereof, I, the said Frederick Bogen, have hereunto set my hand
and seal, this Twenty-third day of October, in the year of our Lord One
thousand eight hundred and seventy-seven.
FRED. BOGEN. (L.S.)