An Electrical Fire Call
Year: 1898

page_text: An Electrical Fire Call,
WILLIAM BLENHEIM, Egham, Surrey, Electrical Engineer, do hereby declare
the nature of this invention to be as follows; -
It is to call firemen in case of fire. It consists of four parts: (1) Apparatus
at fire or central station:-(2) Bells at firemen's houses:-(3) Call points from
which calls to the fire station can be given:-(4) The line wire.
At the fire station is arranged an indicator to indicate from what point the
call has been given, and if required, to call automatically the firemen; and
also an electric generator to work the whole of the apparatus. This electric
generator may be a battery or a continuous current magneto electric generator.
At the firemen's houses is fixed a special call bell, described below.
The calling apparatus to be used by the public consists of a generator to
produce alternating, undulating or intermittent electric currents.
The line wires are connected with the indicator at the fire station also to the
bells at the firemen's houses and to the generator at the call points. The other
terminal of the bells and generator are connected with the earth or a return
wire. It will be noticed that the bells and generator are connected with the
same wire in the same way, that is, between the line and return.
The bells at the firemen's houses have a high resistance, and are so constructed
as to possess a very high magnetic inertia. The magnets are so arranged as to
form as near as possible a closed magnetic circuit. The object of this high mag-
netic inertia is to avoid as much as possible leakage through the bells, of the
current sent from the call points.
In the call box is arranged a magneto electric generator that sends into the
line an alternating, undulating or intermittent current. This will not leak
through the bells on account of their high magnetic inertia, but will set in
action the indicator at the fire station. The indicator will shew the position of
the call point from which the call has been given. It will also put in action
a battery or magneto generator wherby a current is put into the line which
being a continuous one will set in action the bells at the firemen's houses con-
nected with the line.
The magneto generator at the station can be driven by a spring or a weight
which is released by the indicator, in which case no battery will be necessary.
The advantages of my invention are as follows:-
(1) The firemen's calls and call points are connected to the same wire, thus
avoiding separate wires from each call point to the fire station.
(2) The whole can be worked without a battery.
(3) There is no outside wire charged with electricity excent during the verv
short time that a call is being given. This prevents the leakage from the bat-
tery and the corroding of the apparatus &c.

page_text: (4) No false calls can occur through the line coming in contact with another
conductor.
Dated this Twenty-second day of January 1898.
WILLIAM BLENHEIM, Egham, Surrey, Electrical Engineer, 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:-
-
It is to call firemen in case of fire. It consists of four parts, (1) Apparatus at
fire or central station. (2) Bells at firemen's houses. (3) Call anparatus fixed
at points, from which calls to the fire station can be given. (4) Line wire. At
the fire station is arranged an indicator, to indicate from what point the call
has been given, and if required to call automatically, the firemen, and also an
electric generator to work the whole of the apparatus. This electric generator
may be a battery or a continuous current magneto electric generator.
At the firemen's houses is fixed a special call hell, described below.
The calling apparatus, to be used by the public, consists of a generator to
produce alternating, undulating or intermittent electric currents.
The line wires are connected with the indicator A at the fire station, also to
the bells "A" at the firemen's houses and to the generator at the call points "B."
The other terminals of the bells and generator are connected with the earth as
shewn in drawing with a return wire, "A" bells, "B" generator at call points,
"C" apparatus at fire station, D generator. It will be noticed that the bells and
generator "B" are connected with the same wire in the same way as that
between the line and earth. The bells at the firemen's houses have a high
resistance and are so constructed as to possess a high magnetic inertia. The
magnets are so arranged as to form, as near as possible, a closed magnetic
circuit. The object of this high magnetic inertia is to avoid as much as pos-
sible leakage through the bells, of the current sent from the call apparatus "B."
In the call box "B" is arranged a magneto electric generator that sends into
the line an alternating, undulating or intermittent current. This will not leak
through the bells on account of their high magnetic inertia but will set in
action the indicator "C" at the fire station. The indicator will show in this
case by the dropping of the shutter, the position of the call point from which the
call has been given. It will also put in action a battery (by making contact
with the spring in connection with the battery "D" as shewn) or magnetic gene-
rator wherby a current is put into the line, which being a continuous one will
set in action the bells "A" at the firemen's houses connected with the line. In
place of a battery "D," a magneto generator can be used which can be driven
by a spring, or a weight which may be released by the indicator, in which case
no battery will be necessary.
The advantages of my invention are as follows:-
1. The firemen's calls and public call points are connected to the same wire,
thus avoiding separate wires from each call point to the fire station.
2. The whole can be worked without a battery.
3. There is no outside wire charged with electricity, except during the very
short time that a call is being given. This prevents the leakage from the
battery and the corroding of the apparatus, &c.

page_text: 4. No false calls can occur through the line coming into contact with any
other conductor.
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:
The use of call bells of high magnetic inertia, which are connected to the same
wire as the calling apparatus, and arranged as described and shewn in drawing
in such a manner that the same wire that gives the call to the firemen will also
act as call wire from the calling apparatus to the fire or central station.
Dated this 22nd day of October 1898.