Improvements in Burglar Alarms.
Year: 1892

page_text: Date of Application, 7th Dec., 1892-Accepted, 7th Jan., 1893
COMPLETE SPECIFICATION.
Improvements in Burglar Alarms.
I MATTHEW HENRY BARBER of 10 Corporation Street, Manchester in the
County of Lancaster, 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 :-
This invention relates to improvements in electric burglar alarms and especially
to such as are applied to windows, the object being to prevent the possibility of
any unauthorized person entering the room or apartment from without through the
window to which it is applied without sounding the alarm bell. The alarm may
also however be applied to doors.
My invention will be readily understood from the following description and the
drawings accompanying the same on which
Fig. 1 illustrates the apparatus and its application to a window sill (shewn in
section) Fig. 2 is a plan view of the same and Fig. 3 shews a detached part
hereafter alluded to.
The drawings are made on an exaggerated scale for the sake of better
illustration.
According to my invention I fix to the sill a of the window, preferably in a
bored recess or hole as seen at Fig. 1 a plate b through which passes a sliding rod
bar or pin c provided with a spring d or equivalent device for holding it in place.
The rod bar or pin c is formed or provided at the top with an inclined crank or
crook ex and, below the plate it is carried in a suitable bracket e or equivalent
bearing and it is provided with a projection c¹ which is in electrical connection with
a wire a forming one end of the circuit of an electric alarm or bell fixed in any
desired room or place.
This projection c¹ is set between two projections f and g on a bracket / insulated
from the plate b and rode by an ebonite block or otherwise and in electrical
connection with the wire x forming the other end of the above named electric
circuit.
I also fix a metal strap or loop i (shewn also detached at Fig. 3 and by preference
round in section as shown on Fig. 1) to the rod or the lower bar k of the window
blind, in such a position that when the latter is drawn down, the strap i can be
passed under the incline or crook e* and maintain the rod, bar or pin c in the
position illustrated so that the projection c¹ will be out of contact with both f
and g.
The alarm is thus set ready for action, but as soon as the blind is pushed inwards
(so that the strap i acts on the incline e*) or pulled up in the slightest degree the
rod bar or pin c will be lifted by the said strap or loop i and the projection c¹ will
come into contact with f, or if pushed further inwards so as to disengage the
crook c* from the strap or loop i the projection e¹ will come into contact with g.
In either case the electric circuit will be completed and the alarm instantly
sounded.
It will be evident that the projection c¹ may be upon the bracket h and the
projections and g (or the slot) may be carried by (or formed in) the rod bar or
pin c.
It will be evident also that with very slight modification the alarm can be
applied to doors, the loop i being fixed to the door or to a strap cord or blind drawn
across the nanels thereof.

page_text: 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
elaim is-
The improvements in burglar alarms constructed and operating substantially as
hereinbefore described and illustrated by the annexed drawing.
Dated this 6th day of December 1892.
M. H. BARBER.