AN IMPROVED CONSTRUCTION OF ALARUM APPARATUS
Year: 1881

page_text: LETTERS PATENT to Percival Everitt, of Queen Victoria Street, in the City
of London, Engineer, for an Invention of "AN IMPROVED CONSTRUCTION OF
ALARUM APPARATUS."
PROVISIONAL SPECIFICATION left by the said Percival Everitt at the Office
of the Commissioners of Patents on the 7th February 1881.
PERCIVAL EVERITT, of Queen Victoria Street, in the City of London, Engineer.
"AN IMPROVED CONSTRUCTION OF ALARUM APPARATUS."
The object of this Invention is to provide at a small cost an alarum which may
be used to guard entrances against the surreptitious approach of burglars, and it
may also be used to announce the presence of a visitor at a shop or warehouse.
The apparatus is adapted both to doorway and window openings, and it may be
used with advantage to give warning of an accidental conflagration. The apparatus
in its simplest form may be described as consisting of a spindle, which terminates
in a spike or wood screw, and carrying loose upon it a barrel to which two fine
threads or cords are attached. To the free end of one cord a weight is connected,
and to the free end of the other cord a ring or loop is attached for catching onto
a stud, fixed in some place adjacent to the opening to be guarded.
The spindle which carries the barrel has attached to it a bell, and within the
bell a hammer having an elastic stem is mounted. Projecting from the end of the
barrel near the hammer are stud pins or tappets, which are intended as the barrel
rotates to lift the hammer and letting it go suddenly, cause it to strike the bell.
This will be repeated for every stud or tappet that passes the hammer stem. To
apply the apparatus it is only necessary to drive the spike or screw of the spindle
into a wall or other fixed point, and draw from the barrel the cord having the ring
or loop across the space to be guarded, and then to hook the ring onto the fixed
staple prepared to receive it. The second cord will at this time be wound upon
the barrel, the weight being in suspension. If now a person attempts to pass, the
cord will be unhitched, and the weight being thus released, it will pull round the
[Price CdJ1

page_text: barrel, thereby causing the hammer to operate upon the bell until the weight has
dropped to its lowest position.
As any desired length of cord for carrying the ring or loop may be adapted to
this apparatus, it may be conveniently used for guarding the entrance to a
warehouse, the attendant on which is posted at a considerable distance from the
entrance, and should have the alarum situate near him.
When adapting the apparatus as an indicator for fire, I propose to fit the
barrel with a coiled spring instead of a weighted cord for setting the hammer in
action.
On the flame reaching the extended tension cord the spring will be released,
and driving round the barrel it will cause the hammer to sound the alarum.

page_text: the
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Percival Everitt in the Great Seal Patent Office on
6th August 1881.
PERCIVAL EVERITT, of Queen Victoria Street, in the City of London, Engineer.
"AN IMPROVED CONSTRUCTION OF ALARUM APPARATUS,"
The object of this Invention is to provide at a small cost an alarum which may
be used to guard entrances against the surreptitious approach of burglars, and it
may also be used to announce the presence of a visitor at a shop or warehouse.
The apparatus is adapted both to doorway and window openings, and it may be
used with advantage to give warning of an accidental conflagration.
In the accompanying Drawing I have shewn two arrangements of alarum
apparatus, the one being intended for signalling the entrance of a visitor, and the
other the occurrence of fire.
Fig. 1 is a longitudinal section of the more simple form of the apparatus, and
Fig. 2 is an end view of the same partly in section, the bell which sounds the
alarum being removed the better to shew the construction of the parts.
The apparatus in this its simplest form is provided with a central spindle A,
which terminates at one end in a wood screw, or it may be a spike. Mounted
loosely upon this spindle is a sleeve which carries a barrel B, to which two fine
threads or cords C, C¹, are attached. To the free end of the cord C a weight c is
connected, and to the free end of the cord C¹ a ring or loop c¹is attached for
catching onto a stud fixed in some place adjacent to the opening to be guarded.
The spindle A has attached to it a bell D, and within the bell a hammer e,
having an elastic stem, is mounted. The stem of this hammer is made fast to a
short rock shaft E, which is mounted in a bracket bearing a attached to the
spindle A.
The inner end of this rock shaft E carries a tappet, which lies within an annular
space between two rings of tappets carried by a disc F. These rings of tappets
serve by their rotation to impart an axial motion to the rock shaft alternately
in opposite directions, and thereby to vibrate the hammer carried by the rock
shaft and set the bell sounding.
On the sleeve which carries the barrel B is keyed a ratchet wheel G into tho
teeth of which takes a spring pawl g mounted on the disc F.
To apply this apparatus it is only necessary to drive the screw of the spindle
into a wall or other fixed point, and draw from the barrel the cord C' having the
ring or loop across the space to be guarded, and then to hook the ring onto a
fixed staple prepared to receive it. The weighted cord C will at this time by the
drawing off of the cord C be wound up upon the barrel, the spring pawl having
yielded to the rotating ratchet wheel and thereby provided for the alarum
remaining silent.
If now a person were to attempt to pass through the guarded space the cord
would be unhitched, and the weight being thereby released it would pull round the
barrel in the opposite direction, thereby causing the hammer to operate upon the
bell until the weight has dropped to its lowest position.
As any desired length of cord for carrying the ring or loop may be adapted to
this apparatus it may be conveniently used for guarding the entrance to a
warehouse, the attendant on which is posted at a considérable distance from the
entrance, and should have the alarum situate near him.
For the purpose of arresting tho action of the hammer I drill the bell end of the
spindle A to receive a rod or wire fitted with a button H. The spindle A I slot
laterally to allow of the bent up end of this wire to protrude and reach the stem

page_text: of the hammer. By pressing on this button the bent up end of the wire will come
into the plane of motion of the hammer stem and arrest the vibration of the
hammer.
When adapting the apparatus as an indicator for fire I propose to fit the barrel
with a coiled spring instead of a weighted cord for setting the hammer in action.
This arrangement is shewn in the longitudinal section, Fig. 3, where I is the
coiled spring, taking the place of the weighted cord C. In this example the
attachment of the apparatus to the wall or other fixed part of the apartinent in
which it is placed is not effected through the central spindle, but by a bracket
extending from a case K. which encloses the main part of the apparatus.
This case forms a bearing for the spindle A, and to this spindle the barrel B is
made fast. The coiled spring I is connected at its outer end to the case K, and at
inner end to the spindle A.
The rock shaft which actuates the hammer has for its bearing a bracket attached
to the case.
The bell is in this instance carried by a hollow central stud K¹ pro-
jecting from the case, and it is through this stud that the wire for checking the
action of the hammer is inserted. When this apparatus is set in a warehouse or
other place at a tell-tale for fire, on the flame reaching the extended tension cord
the spring will be released, and driving round the barrel it will cause the hammer
to sound the alarum.
Having now set forth the nature of my Invention of "An Improved Construction
of Alarum Apparatus," and explained the manner of carrying the same into effect,
I wish it to be understood that under the above in part recited Letters Patent, I
claim,―
First. Fitting alarum apparatus with a thread or cord for holding the apparatus
quiescent, and releasing the apparatus in the manner and for the purpose above set
forth.
Second. The arrangement of apparatus, described with reference to Figures 1
and 2 of the Drawing, for setting an alarum in action.
Third. The arrangement of apparatus, described with reference to Fig. 3 of the
Drawing, for setting an alarum in action by the severance by fire of a tension
thread or cord.
In witness whereof, I, the said Percival Everitt, have hereunto set my hand
and seal, the Fifth day of August, in the year of our Lord One thousand
eight hundred and eighty one.
PERCIVAL EVERITT. (L.S.)