Improvements in Electrical Thief Detectors.
Year: 1889

page_text: Date of Application, 6th June, 1989
Complete Specification Left, 6th Mar., 1890-Accepted, 6th June, 1890
PROVISIONAL SPECIFICATION.
Improvements in Electrical Thief Detectors.
I HARRY WILLIAM CHARLES Cox, of 11, Galway Street, Bath Street, City Road,
London Electrician do hereby declare the nature of this invention to be as
follows:-
7.
My invention relates to improvements in Electrical Thief Detectors, and has for its
object, to give instant notice of a door or window being opened.
In carrying out my invention, I provide a sort of rectangular box of metal, whose
bottom is extended a short distance beyond each end, for the purpose of being sunk
into, and screwed to the framing of a window or door, in a similar manner to an
ordinary lock. Inside the box, and in the centre of the two sides, I pivot a lever
midway between its two ends, so as to form a "rocking bar," underneath one end of
which I fix a semicircular piece of metal, which projects through a rectangular slot in
the bottom of the box. On the upper surface of the same end of this lever, a spring
presses, which always keeps the semicircular piece of metal forced outwards, except
when the apparatus is not in actual use. The whole mechanism is covered in by a lid
which has the advantage of excluding all dust and dirt. On the outside of the lid,
and near one end, is screwed a small washer of vulcanite, or other suitable insulating
material, the screw being long enough to reach sufficiently far inside the box to touch
the lightest end of the lever, when the apparatus is in action.
The apparatus acts as follows:-
==
The window or door being closed, the semicircular projection is forced inwards, in
a similar manner to the latch of a door; consequently the light end of the lever is
kept away from the insulated screw, in the lid of the box. When the window or door
is opened, the semicircular projection is immediately forced out, under the action of
the spring, thus causing the light end of the lever to touch the insulated screw;
therefore completing the circuit, which was hitherto broken, and causing a bell
to ring.
On the window or door being closed, the lever returns to its' normal' position; the
contact is again' broken, and the bell ceases to ring
Dated this Red day of 1000
HARRY WILLIAM CHARLES COX;
11, Galway Street, Bath' Street, London, EC..
COMPLETE SPECIFICATION.
Improvements in Electrical Thief Detectors.
I, HARRY WILLIAM CHARLES Cox of 11 Galway Street Bath Street City Road
London EC. Electrician 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 :-
My Invention relates to improvements in electrical thief detectors, and has for its
object to give instant notice of a door or window being opened.
In carrying out my Invention, I provide a sort of rectangular metal box, whose
bottom is extended a short distance beyond each end, for the purpose of being sunk
into & screwed to the framing of a window or door in a similar manner to an ordinary
lock. Inside the box and in the centre of its two sides, I pivot a lever midway
between its two ends, so as to form a "rocking bar," underneath one end of which I
fix a semicircular piece of metal, which projects through a rectangular slot in the
bottom of the box. On the upper surface of the same end of this lever a spring
[Price 6d 1

page_text: presses which always keeps the semicircular piece of metal forced outwards, except
when the apparatus is not in actual use. The whole mechanism is covered in by a lid,
which has the advantage of excluding all dust and dirt. On the outside of the lid and
near one end is screwed a small washer of vulcanite, or other suitable insulating
material, the screw being long enough to reach sufficiently far inside the box to touch
the lightest end of the lever when the apparatus is in action.
And in order that my Invention may be more fully understood, I have shewn the
same in the accompanying sheet of illustrative drawings, in which Fig. 1 represents
my improved thief detector, one of the sides having been removed to shew the
internal mechanism. A represents the metal box, the front part of which, B, forms
the fastening plate as in an ordinary lock. This box is let into the door jamb to
which the hinges are secured, or into the lower jamb of the window sash if the
apparatus is to be used for a window alarm. C is a projecting piece forming part of
the lever D, which is flexible, and hinged at E, and kept pressed against the insulated
contact screw F, by the spring G, when the apparatus is in action.
The apparatus acts as follows:-
The window or door being closed, the semicircular projection C is forced inwards,
in a similar manner to the latch of a door, consequently the light end of the lever D is
kept away from the insulated screw F in the lid of the box. When the window or
door is opened, the semicircular projection is immediately forced out under the action
of the spring G, thus causing the light end of the lever to touch the insulated screw,
therefore completing the circuit, which was hitherto broken, and causing a bell to
ring.
On the window or door being closed, the lever returns to its normal position and
the contact is again broken as far as this apparatus is concerned, but the bell may
still continue ringing, if desired, by means of an independent circuit, caused by the
opening of the window or door, & which circuit cannot be broken except by some
person inside the building.
Fig. 2 shews a modified arrangement of the lever D. The bar H is partly cut
through in the centre, and the lever D is fixed in the recess thus formed. A hole is
drilled throughout the length of the bar H, for the purpose of admitting a screw I,
which passes through the bar H, & the eye of the spring, thus keeping it in position
on the top of the said lever D, the screw I serving the same purpose as the pivot E.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improved thief detector constructed, arranged, and operating substantially
as and for the purpose described, and as shewn in the accompanying sheet of
drawings.
2. The modified construction and arrangement of the lever D, and spring G,
substantially as described and shewn in the accompanying sheet of drawings.
Dated this Sixth day of March 1890
HARRY WILLIAM CHARLES COX,
11, Galway Street, City Road, London, E.C.