IMPROVEMENTS IN SIGNALLING BY ELECTRICITY
Year: 1878

page_text: LETTERS PATENT to Edward Brailsford Bright, of 11, Delabay Street,
Westminster, in the County of Middlesex, Civil Engineer, for the Invention
of "IMPROVEMENTS IN SIGNALLING BY ELECTRICITY."
Sealed the 21st March 1879, and dated the 26th September 1878.
PROVISIONAL SPECIFICATION left by the said Edward Brailsford Bright
at the Office of the Commissioners of Patents on the 26th September 1878.
EDWARD BRAILSFORD BRIGHT, of 11, Delahay Street, Westminster, in the County
of Middlesex, Civil Engineer. "IMPROVEMENTS IN SIGNALLING BY ELECTRICITY."
In my Invention I cause warnings of fire, or calls for assistance or services to be
given from various points in streets or buildings by means of artificial electrical
resistances, whereby the locality of the warning or nature of the call is indicated
by the agency of the difference in the electrical resistance of the conducting wire
which is placed in circuit by a finger key or connecting plug or other nicans
of making or breaking electrical contact. I place such artificial resistances in posts
or boxes fixed in the streets or buildings, and by differential coils connected with
corresponding artificial electrical resistances and actuating magnets or armatures
at the place to which it is desired to communicate the signals; such signals are
there made known by an electrical alarum and indicated to the sight or recorded on
paper..

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Brailsford Bright in the Great Seal Patent Office on the
24th March 1879.
EDWARD BRAILSFORD BRIGHT, of 11, Delahay Street, Westminster, in the County
of Middlesex, Civil Engineer. "IMPROVEMENTS IN SIGNALLING BY ELECTRICITY."
My Invention consists in the employment of electrical measures of resistance
placed in posts or boxes fixed in streets or buildings whereby a warning of fire or
a call of any kind is given by a finger key, connecting plug, or push knob, or other
convenient means of making or breaking or varying an electrical circuit or circuits.
By this means the locality of the warning or call is indicated by balancing the
electrical resistance of the conducting wire in combination with such electrical
measures of resistance, by the use of differential coils connected to the apparatus at
the fire brigade station or other place to which the call is given, which is furnished
with corresponding electrical measures of resistance.
Or instead of differential coils the bridge arrangement may be used for balancing
the line and local circuits.
Figures 1 and 2 show the side and front of the upper part of a street post
(partly in section) fitted with my Invention. A is the "localiser" (or electrical
measure of resistance) consisting of a coil of insulated wire which may be as shown
an electro-magnet. The length of wire in the "localiser" is varied according to the
electrical resistance which it is desired to place in circuit, and its ends are con-
'nected severally to the wires B, C, which with the "localiser" form part of the line
circuit. The wire C is also connected to a metallic block D, which is insulated by
ebonite or other suitable material from the post or box which is connected to the
earth. E is a "push knob " (shown in Fig. 1 but not in Fig. 2) which is in con-
nexion with the metal post or box. On the push knob E being pressed into the
opening in the block D metallic contact is made by means of the wire C between
the "localiser" A and the earth at the post or box.
At the place or station where the warning or call is given by this means, I
employ the same indicating apparatus as described in my Patent dated the 13th
February 1878, No. 596, Figures 4, 5, 6, 8, 9, 10, and 11. The series of resistance
coils in such indicating apparatus corresponds in electrical resistance with the series
of "localisers" in the posts or boxes and the line wire. One pole of a galvanic
battery (or other suitable means of producing electricity) is connected to the
starting end of the line wire at the place or station at which the warning or call is
indicated, and the other pole is connected to earth.
A diagram of the arrangement of circuits which I prefer is shown in Figure 3,
where a series of street posts lettered G are shown with their "localisers" numbered
from 1 to 7 inclusive. At H the fire brigade station or other place to which the
warning or call is given, the indicating apparatus consists of differential coils i
acting upon a balanced magnet k. One end of both of the differential coils is con-
nected through an alarum 7 to one pole of the battery m, the other pole of the
battery being connected as shown to earth. The other ends of the differential coils
are connected as follows:-One to the line wire n and thence through the
"localisers in the posts or boxes, and the other to the end of the set of local
resistance coils lettered o, which correspond with the resistance of the line wire
and "localisers," and can be brought successively into circuit by the contact arm p
(which is connected to earth as shown) until an electrical balance is obtained
between them and the line wire with its "localisers" to the point of warning or
call where the connexion with earth at the post or box is made by the push knob.
To give an answering signal from the station to the post or box in acknow-
ledgement of the warning or call it is only necessary to have an ordinary telegraphic
finger key connected at the station which will break the connexion between the
battery and the line wire when pressed. Upon this the armature and sounder

page_text: shown at F, Figures 1 and 2, will be acted upon as many times as required by the
temporary withdrawal of the current by the key shown at q, Fig. 3.
In Figure 3 seven posts are shown, but more can be connected on a circuit as
required.
With the view of having each post in thorough connexion with the earth it is
desirable in order to provide against the ground at the base of any post being
exceptionally dry to connect each post to the iron pipe in which the conducting
wire is laid when underground, or in the case of overground wires to connect the
post or box with the nearest gas or water pipe.
In the case of street posts or boxes the door opposite the push knob may be
opened by keys issued to the police and other responsible persons, and a plate of
glass may be placed in the door which can be broken by any person wishing to
give a warning or call by means of the push knob and not having a key.
Instead of a push knob being employed a series of numbered keys may be issued
to the police and householders, and on a key being put into a post the key itself
makes the requisite contact between the "localiser and the earth to give the
warning or call. A spring or clip inside the post against which the key presses
will by means of a notch or stud on the key prevent the withdrawal of the key
except by a master key in the hands of the fire brigade or police, and thus check
false alarms being given.
Words such as "fire alarm" may be prominently shewn on the posts or boxes
in red or other colour, and at night I consider it desirable that such words should
be illuminated by a small gas jet placed within each street, post, or box, the letters
being transparent.
Having thus described my Invention, and the best means I am acquainted
with for carrying the same into effect, I wish it to be understood that what I
claim is,―
Firstly. Indicating the place from which a warning, call, or other signal is com-
municated by means of artificial measures of electrical resistance (or rheostats) in
combination with finger keys or other suitable means of making, breaking, or
varying an electrical circuit.
Secondly. The general arrangement and construction of apparatus, substantially
as described.
In witness whereof, I, the said Edward Brailsford Bright, have hereunto set
my hand and seal, this Twenty-fourth day of March, in the year of our
Lord One thousand eight hundred and seventy-nine.
Witness,
CHARLES T. BRIGHT, Knight,
11, Delahay Street
Westminster.
E. B. BRIGHT. (L.S.)