An Improvement in or Connected with Electrical Connections for Burglar Alarms.
Year: 1889

page_text: Date of Application, 17th Jan., 1889
Complete Specification Left, 17th Oct., 1889-Accepted, 23rd Nov., 1889
PROVISIONAL SPECIFICATION.
An Improvement in or Connected with Electrical Connections for
Burglar Alarms.
We, JOHN CRISP FULLER, and GEORGE FULLER, both of Newcastle Wharf Works,
Old Ford Road, Bow, in the County of Middlesex, Electricians and Telegraph
Engineers, do hereby declare the nature of this invention to be as follows:-
In the existing forms of electrical contacts used in buildings to give an alarm in
case of the attempted entrance of burglars or other unauthorized person or persons an
arrangement is now used in which a spring is compressed by the window or door.
The releasing of this spring makes contact and thus causes the electrical alarm bell to
ring. In practice however it is found that the spring is a constant source of trouble;
it either oxydates and decays or else takes a permanent set, and consequently at the
required moment is not in a condition to act. To remedy this fault we dispense with
a spring of any kind whatever and substitute a falling weight or lever.
The pressure
By
of the door or window lifts this lever and thus keeps the contacts apart, but as soon as
the pressure is taken off, the lever falls and completes the electrical connection.
our invention we thus make a contact, suitable either for windows or doors, that
cannot get out of order, that has no springs to corrode or set, and that can be fitted
with an ordinary centre bit by any common workman.
Dated this 17th day of January 1889.
COMPLETE SPECIFICATION.
An Improvement in or Connected with Electrical Connections for
Burglar Alarms.
We, JOHN CRISP FULLER, and George Fuller, both of Newcastle Wharf Works,
Old Ford Road, Bow, in the County of Middlesex, Electricians and Telegraph
Engineers, 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 the existing forms of electrical contacts used in buildings to give an alarm in
case of the attempted entrance of burglars or other unauthorized person or persons,
an arrangement is now. used in which a spring is compressed by the window or
door. The releasing of this spring makes contact and thus causes the electrical
alarm bell to ring. In practice however it is found that the spring is a constant
source of trouble, it either oxydates and decays, or else takes a permanent set, and
consequently at the required moment is not in a condition to act. To remedy this
fault we dispense with a spring of any kind whatever and substitute a falling weight
or lever.
The pressure of the door or window lifts this lever and thus keeps the contacts apart,
but as soon as the pressure is taken off, the lever falls and completes the electrical
connection, and in order that our invention may be more fully understood we will
describe same with reference to the accompanying drawings.
Figure 1 is an elevation, and Figure 2 a plan, of an apparatus constructed according
to our invention.
A is the weighted lever, B the fulcrum of same, (is a plate to which the weighted
ever A is fulcrummed at B; D is a contact plate having a terminal screw Ď¹ for

page_text: fastening a conducting wire to the said plate D. The plate D may have a platinum
surface if desired. E is a plate of non-conducting material by means of which the
contact plate D is kept away from electrical contact with the plate C. F is an arm
made in a piece with or fastened to the weighted laver A and having preferably a
platinum surface.
The apparatus is fitted to the door or window frame so that when the door or window
is open the weight of the weighted lover A keeps the arm F against the contact plate D
thus allowing the electric current to pass from one terminal G by way of the plate C,
falcrum pin B, weighted lever A, arm F and contact plate D to the other terminal D¹,
thus sounding the aların; but on closing the door or window the said door or window
comes against the projecting part of the weighted lever A and rocks said weighted
lever A on its fulcrum B thus withdrawing the arm F from the contact point D and
breaking the circuit which thus stops the alarm.
By our invention we thus make a contact, suitable either for windows or doors, that
cannot get out of order, that has no springs, and that can be fitted with an ordinary
centre bit by any common workman.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what
we claim is --
1. In burglar alarms, the woighted lever A fulcrummed at B and actuated by the
opening or closing of the door or window, for connecting and disconnecting an electric
current as and for the purposes set forth.
2. In electrical connections for burglar alarms, the combination of the weighted
lever A, fulcrum B, arm F, plate C, contact plate 1) and the two terminal screws G
and D¹ substantially as set forth.
n72
1000