Improvements in and relating to Street and other Fire Alarms.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in and relating to Street and other Fire Alarms.
FRANCIS ELLIOTT STUART Volthurst Ealing London W. Electrical Engineer,
do bereby declare the nature of this invention to be as follows:-
An electrical fire-alarm apparatus, which when used will give a clear, and
distinctive signal that could not possibly be given by another wire coming in
contact with the fire alarm line wire, or by a break on the wire, or by any other
means, except the fire alarm sending apparatus itself.
At the receiving station I provide an ordinary indicator, and electric bell; and
battery; and at the sending, or fire alarm station, I fix a specially constructed
contact maker which is operated by a handle; and which makes and breaks a
contact, by the swing of a peudulum, started by the pull handle; and so arranged
that on each swing; the pendulum joins up an electrical circuit the duration and
rapidity of these contacts being arranged according to the weight and length of the
pendulum.
By means of a mechanism, the pull handle of the fire alarm sending instrument
is so arranged, that it can be pulled, held out, twisted, or pulled repeatedly and
pushed in again; without interfering with the swing of the pendulum, and therefore
allowing the regular intermittant currents to pass from the sending to the receiving
station; which are clearly and easily distinguished from a false alarm.
For the purpose of informing the caller that the bell at the receiving station is
working, and that the call has been received; I place in circuit at the sending
station a bell, either trembling, single stroke or shunt-wound, which will work in
unision and in circuit with the bell at the receiving station.
Dated this Twelfth day of March Eighteen hundred and ninety-five.
FRANCIS ELLIOTT STUART Voltburst Ealing London W. 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:-
In fire alarm apparatus, operated by putting the line wire to earth, at the
transmitting station; and thus closing an electric circuit through an indicator,
bell, or relay, or both; at the receiving station; false alarms continually occur,
through the line wire getting in contact with other wires, or connections leading
to earth, or through a line breaking, and making earth; or through currents from
other circuits leaking on to the fire alarm wire; and also by the wire being struck
by lightning; and in cases of underground wires, through leakage and other
causes.
These improvements are designed to obviate false alarms, by giving a clear and
distinctive signal when the handle at the transmitting station is operated, a
signal that cannot by any ordinary means be given; in ordinary fire alarms, the
Unin 71

page_text: signal is given by making a single contact by means of a pull handle, or push ;
with this new apparatus, I make by a single pull or push, a number of makes and
breaks of a contact, at regular or irregular intervals; which can be done by
several simple mechanical means, and which I here shew made by a pendulum at
the transmitting station.
By giving the pendulum; which is hung on needle points; a start; it swings
backwards and forwards, or from left to right until it is stopped, or exhausts the
momentum, and in thus exhausting itself the swing gets shorter, or smaller and
smaller, with each movement. When this pendulum moves out of its normal
perpendicular position at rest, it joins up or makes contact hetween two pieces of
metal, to which the line wire, and earth wire are connected; thus completing the
electrical circuit, but with each swing the contact is broken as the pendulum passes
the perpendicular. At the receiving station or other end of the fire alarm line the
bell; which can be either a single-stroke bell, or an ordinary trembling bell; rings
in unision with the contacts made by the pendulum; and as the momentum of the
pendulum ceases gradually, making a lighter contact each time, so the bell in the
receiving station is rung slower or with a greater interval between each ring, until
it dies away altogether.
Thus giving a clear and distinctive sigual; which the person at the receiving
station knows can only be given by a person operating the apparatus at the call
point, or sending station; and not by a contact or fault.
In order that my invention may be properly understood, I will now describe the
same with reference to the accompanying sheet of drawings.
The same letters denote the same parts in all the figures.
Fig. 1. shews the pendulum transmitter, with an ordinary single stroke bell in
circuit, and push contact maker for signalling.
In Fig. 1. A. is the pendulum, weighted at the end A 1; A 2. is the position of
the pendulum when swinging, and making contact with the two springs B1 and B2,
one of which only is shewn in this figure; C, and D, are the contact pieces of an
ordinary contact maker for signalling; E, is the dome of the bell; F, and F 1, are
the coils, and G is the hammer pivotted at H; I is a stop for the hammer to rest
against, when not in use.
In Fig. 2. which is the top view of the pendulum contact pieces, shewing the
means of hanging the pendulum, A, centered at K; and shewing the two contact
pieces B1 and B2.
Fig. 3. represents the arrangements at the receiving station, and consists of an
ordinary electric bell, indicator, Morse key, and battery. These are not shewn in
detail as any ordinary forms may be used.
The electrical connections will be made clear by the dotted lines on the
accompanying drawing.
When the pendulum at the calling, or transmitting station Fig. 1. is operated,
the metal top of the pendulum makes contact between the two springs B 1 and B2;
and a current passes from the earth terminal of the transmitting instrument through
the coils of the bell F, F 1, to contact spring B 1, to contact spring B2, and to
line terminal, to the line wire to the receiving instrument at the receiving station
Fig. 3, to the indicator coils corresponding to the alarm pulled, to the centre of
the reply key, to the back contact through the bell, or relay coils, to battery, and
battery to earth; thus completing the electric circuit.
When the pendulum swings back, it breaks the contact on passing the normal
perpendicular position, and again makes the same contact on the reverse side; and
so backwards and forward as it swings each time the hammer of the bell in the
receiving instrument strikes the bell in unision with the swing.
Should however an earth fault or contact occur on the line wire, or in the
sending instrument, the bell; if a single stroke would only strike once; if a
trembling bell continuously ring; until the contact was off; and the indicator
would also remain down, thus clearly denoting the difference between a genuine
call and a false alarm.

page_text: 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
Itclaim is :-
1. In an electrical fire alarm telegraph the use and employment of a mechanism
or means for making and breaking an electrical contact or contacts a number of
times automatically; after being started by hand; to distinguish at the receiving
station on a bell, indicator, or other apparatus the difference between a false alarm
caused by contacts or other faults on the electrical circuit; and a genuine call
given by a person operating the sending mechanism.
2. The combination with a make and break contact maker as above described
of an ordinary electric indicator, or relay, bell, battery, and reply-key at the
receiving station.
3. The combination with a make and break contact maker and station apparatus
as above described, of a repeater bell at the call point, arranged to ring simul-
taneously with the station bell; or, only when the reply-key is depressed during
the time the sending apparatus is in operation.
4. The combination with each other of the various mechanical parts, and
electrical connections, described above, and illustrated in the accompanying
drawings.
Dated this Fourth day of November 1895.
FRANK E. STUART.