IMPROVEMENTS IN SIGNALLING BY ELECTRICITY
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I EDWARD BRAILSFORD BRIGHT of 31 Golden Square in the County of
Middlesex Civil Engineer do hereby declare the nature of my Invention for
IMPROVEMENTS IN SIGNALLING BY ELECTRICITY, to be as follows:-
In the employment of the Electric Fire Alarins, for which I obtained patents
No 596 and No 3801 in 1878, it has occasionally happened that the person giving
an alarm of fire by means of one of the street call posts has returned the handle
back too soon, before attention was given and the locality of the particular post
noted by means of the apparatus at the Fire Engine Station to which the call was
made.
To provide against this contingency I have devised the following improvements:―
The length of resistance wire in the street post or call box is wound on an iron
core and constitutes an electro-magnet which actuates a movable armature when
the electric current flowing from the Fire Engine station is made to pass through
the electro magnet. This takes place when the alarm handle is pulled out, which
separates two springs which had previously (while in contact with one another)
kept the electro-magnet on short circuit.
To this short circuiting arrangement I add a regulating stop (adjustable by a
screw) against which the movable armature rests when no call is being given; but
on an alarm call being given by pulling the handle, and the current thus diverted
through the electro-magnet by the "short-circuiting" springs being separated, the
armature is attracted to the electromagnet from the stop.
The armature is connected to the line wire in one direction (say the incoming)
and also to one end of the electro-magnet.
The other end of the electromagnet is connected to one of the short circuiting
springs, to which the line wire in the other direction (say the outgoing) is also
joined.
The other short circuiting spring is connected to the stop or stud against which
the armature rests when no call is being given.
Thus in each street call post or alarm box there are two points where the short
circuit in connexion with the electromagnet is closed or opened-Firstly between
the springs moved by the alarm handle, and Secondly between the armature of the
electromagnet and the stop or stud against which it rests when no alarm is being
given to the Fire Engine Station.

page_text: The effect of this arrangement is that when the alarm call is given by pulling
the handle and separating the springs, the movement of the armature from its stop
to the electromagnet makes a second break in the short circuit; so that any
premature replacement of the call handle. alone does not again put the electro-
magnet on short circuit, or interfere with the call signal and the locality of the post
being indicated at the Fire Brigade Station by the resistance wire of the electro-
magnet in the street post.
As soon as the flow of the current is temporarily interrupted at the Fire Engine
Station by the movement of a "make and break" key, the movable armature in
the street post is released from the electro magnet and returns to its stop.
The movable armature is connected to a red disc which is moved before an
aperture in the street post or call box upon the alarm being given, and which is
only moved away again when the acknowledging signal is given on the temporary
cutting off of the current by the 'make and break' key at the Fire Engine
Station as previously described.
I prefer to employ platinum for the points of contact between the armature and
its stop.

page_text: I, EDWARD BRAILSFORD BRIGHT, of 31, Golden Square, in the county of
Middlesex, Civil Engineer do hereby declare the nature of the said invention
for "IMPROVEMENTS IN SIGNALLING BY ELECTRICITY” and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:—
In the employment of the electric alarms or calls for which I obtained Patents
No 596 and N° 3801 respectively in 1878 it has occasionally happened that the
person giving an alarm or call by means of one of the street posts or call boxes has
returned the handle back too soon, before attention was given and the locality of
the particular post or call box noted by means of the apparatus at the Fire Engine
station or other point to which the call was made.
To provide against this contingency I have devised the following improvements
represented in the accompanying drawing in which figure 1, shews the front
elevation of an alarm box constructed according to my present invention; figures 2,
and 4, are side elevations showing the mechanism the sides of the box being
removed; figure 3, is a back elevation showing the internal fittings the back of the
box being removed and figure 5, is an explanatory diagram clearly shewing the
electrical connexions. In figure 5, the alarm handle is indicated in a vertical
instead of a horizontal position in order to make the diagram clearer as to the
electric connexions. Similar letters in all the figures represent similar parts.
The length of resistance wire in the street post or call box is wound on an iron
core and constitutes an electro-magnet a, which actuates a movable armature b,
when the electric current flowing from the fire engine station, or other station, by
way of the terminals i, i¹, is made to pass through the electro magnet α, This
takes place when the alarmı handle c, is pulled out which action separates the two
springs d, e, which had previously while in contact with one another kept the
electro-magnet a, on short circuit.
To this short circuiting arrangement I add regulating stopf, (adjustable by a
screw f¹) against which the movable armature b, rests when no call is being given;
but on an alarm call being given by pulling the handle c, and the current being
thus diverted through the electro-magnet a, when the "short circuiting" springs d, e,
are thus separated, the armature b, is attracted to the electro-magnet a, from the
stop f.
The armature b, is connected to the line wire in one direction (say the incoming)
and also to one end of the electro-magnet a.
The other end of the electro-magnet a, is connected to the short-circuiting
spring e, to which the line wire in the other direction (say the outgoing) is also
joined.
The other short-circuiting spring d, is connected to the stop or stud f, against
which the armature rests when no call is being given. A spring c², is with
advantage attached to the "call" handle c, to return it to its point of rest after
the call is given, as shown in figures 2, and 5.
Thus in each street alarm post or call box there are two points where the short
circuit in connexion with the electro magnet is closed or opened. Firstly, between
the springs d, e, moved by the call handle c, and, secondly, between the armature b,
and the stop or stud f, against which it rests when no call is being given to the fire
engine or other receiving station.
The effect of this arrangement is that when the alarm call is given by pulling
the handle c, and separating the springs d, e, the movement of the armature b, from

page_text: its stop f, to the electro magnet a, makes a second break in the short circuit ;, so
that any premature replacement of the call handle c, alone, does not again put the
electro magnet a, on short circuit, or interfere with the call signal and the locality
of the post or call box being indicated at the fire engine or other receiving station
by the resistance wire of the electro-magnet a, in the street post or call box.
As soon as the flow of the electric current is temporarily interrupted at the fire
engine or other receiving station by the movement of a "make and break" key
placed there to answer the call, the moveable armature b, in the street pöst or call
box is released from the electro magnet a, and returns to its stop f
The moveable armature b, is mechanically connected to à disc h, colored red or
otherwise and which is moved before an aperture in the street post or call box
upon the alarm being given and which is only moved away again when the
acknowledging signal is given on the temporary cutting off of the current by the
"make and break" key at the fire engine or other receiving station as previously
described.
I prefer to employ platinum for the points of contact between the armature and
its stop. The platinum on the armature may be fixed as a light spring.
k, k², are terminals fixed to tlie inner face of the alarm box which, when the face
is fixed in the box, make contact in a convenient manner with springs such äs 1, 7¹;
connected to the outside terminals i, ¿¹.
When a large number of alarm posts or boxes are required on à circuit I find it
preferable to make the coils of the higher resistance of German silver or other low
conducting metal, in order to keep their size small; and if necessary to add a
subsidiary coil to make up the requisite resistance as shewn in figures 2, 3 and 4,
at m.
The indicating apparatus employed at the Fire Brigade stations or other points
to receive calls is the same as already described in the specifications of my said
patents Nos 596 and 8801 of 1878, tlie resistance coils a, in the call posts or boxes
being balanced by similar resistances in a second artificial circuit at the station to
which the call is given.
1
My improved apparatus may be employed för fire, police, or other culls as required.
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 double arrangement for closing or opening the short circuit apparatus in
fire alarm, or call boxes operated by electro magnetic resistance coils so as to
prevent an alarm or call being interfered with by subsequent movements of the
"call" handle until the acknowledging signal is given from the fire engine or other
station as hereinbefore described.
2. The street alarm post or call box apparatus, substantially as described and
represented in the accompanying drawing..
Dated the 4th don of N
4