An Improved Burglar Alarm.
Year: 1896

page_text: Date of Application, 10th Sept., 1896--Accepted. 13th Mar., 1897
COMPLETE SPECIFICATION.
An Improved Burglar Alarm.
We, MARTIN PHILIP MCDERMOTT, Plumber &c., and Dr. JOHN LOGAN
CAMPBELL, Merchant, both of Auckland, in the Colony of New Zealand, 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:-
Our invention relates to a burglar alarm whereby the tampering with the doors,
windows, safes or other fittings of a building can be detected and sigualled by the
movement of the same, completing an electric circuit and actuating a signal bell.
We carry our invention into effect by providing suitable contacts fixed wherever
required, and a special form of relay for maintaining a continuous ringing of the
signal bell when once the latter has been started.
Our invention is illustrated on the accompanying sheets of drawings, on which
similar letters represent like parts in all the figures:-
Figure 1 is a view of our signal bell.
Figure 2 is a view of an ordinary electric bell.
Figure 3 is a view of a switch.
Figure 4 is a view of our relay.
Figure 5 is a view of a pair of electric cells.
Figure 6 is a view of another pair of the same.
Figure 7 is a view of a window fitted with one of our contacts..
Figure 8 is a view of a contact suitable for the tread of staircase or for a floor.
Figure 9 is a view of a contact suitable for a trap door.
Figure 10 is a view of a safe fitted with another form of our contact.
Figure 11 is a view of the contact of the same on a larger scale.
Figure 12 is a view of a contact luck.
Figure 13 is a view of an ordinary door lock.
Figure 14 is a view of the staple of the same fitted with our contact.
In these views (A) Figure 5, are the cells of a battery having attached to their
negative pole wire (N) which passes to switch (b), Figure 3, and thence to electro
magnet at (c). The positive pole of such battery has wire (P) attached. When
the switch is closed, the circuit will be closed when any of the contacts, to be
hereinafter described, are operated the return current passing through wire (P¹) to
electromagnet at (c2). Immediately the circuit of cells (A) is closed, armature (c)
will be drawn towards the magnet until it touches points (p³) and (g) of wires (P)
and (Q) respectively. A current will now pass from cells (B) through wire (Q)
armature (c) wire (P') to bells (Figure 1 and 2); the return current passing
through wire (R) back to battery (B). Also the current will pass from cells (A)
through wire (P) contact (p³) and the relay magnet (c) to wire (N) and switch (b)
hence the magnet is maintained energized and its armature (c) attracted so that
the bells, which may be placed in any desired position either within or without
a building, will continue to ring until switch (b) is actuated to break the circuit.
Referring to the various forms of our contact, Figure 7 shews the mechanical
arrangement by which our burglar alarm is put into action when a window is
being opened, (e) is the bottom sash of the window which is recessed at (el) so
that when the window is in its normal or closed position, the spring (e) which is
attached to wire (P), and spring (e) which is attached to wire (P¹) are out of

page_text: contact as shewn, but as soon as the sash is raised, spring (e) is pressed by the
edge of the sash into contact with spring (3) so that a current of electricity may
continuously pass.
Figure 8 shows a form of contact to be used upon the tread of a staircase, or
fastened in any convenient position, such as to a joist under the floor, a portion of
which is left loose for the purpose. The circuit is closed when the floor above (f)
is trodden upon, and points (f) and (12) made to touch. In a normal condition
the points will be separated by action of spring (ƒ³).
Figure 9 is a contact for use with trap doors when the weight of the latter
will press upon the stud (9) and keep points (g') and (92) apart, against the action
of spring (93). When the trap door is raised the spring will come into play to
cause points (9) and (92) to touch and complete the circuit.
Figure 11 shows on a large scale a contact suitable for safes, the same being
shown in position at (h) Figure 10, and is connected to safe by recessing the casing
to admit back portion of Figure 11, so that the front plate only is visible, the
circuit wires being carried through tube (4), and out of bottom of safe.
the safe is closed, stud (4) is pushed back and points (2) and (3) kept apart, but
when the safe is opened spring (4) forces the said points together and completes
the circuit.
When
Figure 12 shows an auxiliary lock (n) to be used in connection with doors,
whereby the door may be opened without the circuit being closed.
Figure 13 shows the ordinary lock (m) with the bolt (m') shot, and spring (m²)
held by the said bolt out of contact with point (m³).
It will be seen that when bolt (m1) is withdrawn to unlock the door,
spring (m2) will press upon point (m3) and will close the circuit. Lock (n)
which is in the same circuit as lock (m) is therefore provided and must be unlocked,
so as to break the circuit by separating its bolt (n 1) from spring (n2), before
lock (m) is unlocked. The door may then be opened without the signal bells
being operated. Upon leaving a building lock (n) must be locked after lock (m).
Referring to Figure 1, gong (s) and bell stand (s1) are attached to wire (P3),
which is a continuation of wire (P), and bell hammer (s2) is in connection with
wire (P1),
so that if the bell is tampered with and hammer (s2) brought into
contact with projection (3) of stand (s1), or into contact with gong (s) the circuit
will be closed and other bells in the circuit will be made to ring.
It will be obvious that the details of our invention may be modified in several
ways by one skilled in the art to which it appertains without departing from the
principle of the same, and we do not wish it to be understood that in our description
we have exhausted all cases to which our invention is applicable, but our apparatus
is suitable for indicating the tampering with safes and all descriptions of doors,
windows, or openings with which a burglar may tamper.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is,
1. In a burglar alarm an auxiliary lock working in connection with a door lock
for completing the connection of wires after the door is locked, and for breaking
the connection when the door is opened, substantially as, and for the purposes set
forth herein.
2. In a burglar alarm a lock having a spring tongue for completing the connec-
tion of the wires by the withdrawal of the bolt, substantially as, and for the
purposes set forth herein.
3. In a burglar alarm the arrangement of springs to enable contact to be made
and the signal bell rung by the raising of the window sash, substantially as, and
.for the purposes set forth herein.
4. In a burglar alarm the combination of the arrangements shewn in Figures 1, 2, 3
and 4 with dry or wet electric batteries, Figures 5 and 6 actuating electric bells
Figures 1 and 2, substantially as, and for the purposes set forth herein.

page_text: 5. In a burglar alarm an electro magnetic apparatus as illustrated in Figure 4,
having contact points which touch the armature when the latter is drawn towards
the magnet by the unlocking of the door, or raising the sash, or the like, and thus
putting the signal bells into continuous action, substantially as, and for the purposes
set forth herein.
6. In a burglar alarm the arrangement of parts as shewn in Figure 8, to enable
contact to be made, and the signal bells rung by the treading upon a loose stair
tread or the like, substantially as, and for the purposes set forth herein.
7. In a burglar alarm the arrangement of parts as shewn in Figure 9 to enable
contact to be made, and the signal bells rung by the raising of a trap door and
the like, substantially as, and for the purposes set forth herein.
8. In a burglar alarm the arrangement of parts as shewn in Figure 9 to enable
contact to be made, and the signal bells rung by the opening of a safe door,
substantially as, and for the purposes set forth herein.
9. In a burglar alarm the arrangement of parts by which other bells in the
circuit are made to ring when hammer of bell shewn in Figure 1 is tampered with,
substantially as, and for the purposes set forth herein.
10. The whole combination and arrangement of parts constituting our improved
burglar alarm as, and for the purposes described herein, and illustrated on the
accompanying drawings.
Dated thie Tonth dor of Sontombar 1906
W. P. THOMPSON & Co.,
322 High Holborn, W.C., Patent Agents for the Applicants.