Improvements in Burglar Alarms.
Year: 1892

page_text: Date of Application, 13th Sept., 1892-Accepted, 15th Oct.; 1892
COMPLETE SPECIFICATION.
Improvements in Burglar Alarms.
I, HOMER TONG WILSON, of Louisville, in the County of Jefferson, and State
of Kentucky, United States of America, Clergyman, 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 burglar alarms, and more particularly to the con-
struction of the contact device.
The objects of the invention are to simplify such contact device whereby it is
compact and can be readily applied to a door, window or other object without the
necessity of previous preparation in the way of channeling said object for the
reception of the device.
With these objects in view the invention consists in two contact spring plates
whose contacting ends are normally contacting, which plates are provided in rear
of their contacting ends with screw-receiving openings an intermediate insulating
block having corresponding registering openings and interposed between the
perforated portions of the contact plates, which blocks are provided at opposite
sides with wire terminal receiving grooves, and in screws passing from the outside
through the plates and insulating block and serving to clamp the three together,
and thus secure the wire terminals as well, and also serve to secure the device in
position.
In the accompanying drawings
Figure 1 is a perspective view of a portion of a window provided with a device
constructed in accordance with this invention.
Figure 2 is a longitudinal sectional view of the same.
Figure 3 is a perspective view of the several parts of the device separated.
Referring to the accompanying drawings A represents an ordinary window
frame carrying the sliding sash B which is provided with a projecting oval-headed
screw or stud C secured to the lower sash rail at any suitable point thereon.
Secured to the window-sill at a point adjacent to said screw or stud upon the
lower sash rail are the upper and lower contact plates D and D₁ respectively
which are adapted to close and break the electric circuit at the proper time in
order to give the requisite alarm when the window sash is moved even so far
as an eighth of an inch. The said contact plates D and D₁ are spaced and
insulated from cach other at one end by the insulating block E placed there
between and are clamped to each other, to the insulating block and secured to
the window-sill by means of the securing screws F passing through per-
forations f, in each plate and said insulating block, said perforations in the
lower contact plate being sufficiently large to allow the screw to pass there-
through without contacting with the plate and thus keeping the said plates
effectually separated from each other said screws being sufficiently long to project
through the two plates and insulating block and beyond the same a sufficient
distance to penetrate the object upon which the device is secured, thus serving
the double function of securing the parts together composing the device and also
serving to secure said device to the object. It will be seen that by passing the
screws from the outside that the heads of the screws are upon the outside of the
device, while the under or inner side of the device is flat and consequently no
previous preparation or channeling of the object to which the device is secured
is required, and hence it can be sold to the public and applied by persons not
possessing mechanical skill.
The said insulating block E is provided with opposite wire grooves e, upon
each face thereof and which are designed to receive the bared ends of the aların

page_text: circuit wires G which are fitted in said grooves and are also clamped therein by
means of the contact plates clamped thereon by the screws F and which are thus
placed in circuit with said wires."
The upper contact plate is provided with a short downturned contact end H
while the lower plate D is provided with a longer upwardly pressing spring
contact end I which starts in rear of the contact end of the upper plate and extends
out beyond the same into the path of the screw or stud C secured to the lower
sash rail, the tendency of said spring contact end being to hold the same in contact
with the upper contact plate and thereby close the electric circuit which allows the
alarm to ring until the circuit is broken.
When the window is down the said screw or stud engages the projecting end of
the spring contact end I and presses the same below and out of contact with the
upper plate thereby breaking the circuit, but upon the slightest upward movement
of the window the circuit is immediately closed in the manner already stated and
the alarm sounds at once.
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
The herein described contact device adapted to be used in connection with a
projection on the lower rail of a window sash or other object, the same consisting
of the inner and outer spring contact plates provided with aligned perforations
near one end, an insulating block interposed between the plates and provided with
aligning perforations and at opposite sides with wire receiving grooves, and screws
passed through the aligned perforations of the plates and intermediate insulating
block and adapted to project beyond the same into a window-sill or other object
and to clamp the plates, block and wires, said plates having their ends beyond the
block bent and adapted to contact, substantially as set forth.
Dated this 13th day of September 1892.
W. P. THOMPSON & BOULT,
Agents for the Applicant.