IMPROVEMENTS IN THE CONSTRUCTION OF LOCKS
Year: 1853

page_text: LETTERS PATENT to Michael Leopold Parnell, of the Strand, in
the County of Middlesex, Lock Manufacturer, for the Invention
Sealed the 27th January 1854, and dated the 9th September 1853.
PROVISIONAL SPECIFICATION left by the said Michael Leopold
Parnell at the Office of the Commissioners of Patents, with his
Petition, on the 9th September 1858.
I, MICHAEL LEOPOLD PARNELL, of the Strand, in the County of
Middlesex, Lock Manufacturer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF LOCKS" to be
as follows:-
The improvements are set forth and represented in the annexed
Drawing. a, a, are the levers or tumblers, supported on a pin or
fulcrum b, placed at or near the center of the tumblers, instead of the
end, as in the ordinary plan; b', is the bolt; c, is a notch at the outer:
end of the levers to receive the lock stop c'; and d, is a notch at the
opposite end of the lever to receive the detector stop d'. Upon the
outer end of each of the levers (or it may be in any other convenient
part) are formed two inclined planes e, e', and springs f, are placed in
such position as to be capable of acting upon either incline, so as to
move the tumblers in opposite directions. When the bolt is shot the

page_text: springs pressing upon the inclines e, force the tumblers against the
locking stop c', so as to retain it in the notch c; but if an attempt be
made to pick the lock the moment any of the tumblers is lifted too
high the pressure of the corresponding spring becomes transferred to
the incline e', of that tumbler, and the tumbler is thereby forced into
contact with the detector stop d', which enters the notch d, and is
retained therein by the pressure of the spring upon the incline e'. g, is
a horizontal stop acting against the butt end of the levers when the
bolt is shot out.
I claim as constituting my Invention the supporting the tumblers or
levers upon a central axis, the arrangement for maintaining a tumbler
in contact with the detector stop after the withdrawal of a false key,
and, lastly, the horizontal stop..
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Michael Leopold Farnell in the Great Seal Patent
Office on the 9th March 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
MICHAEL LEOPOLD PARNELL, of the Strand, in the County of Middlesex,
Lock Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of September, in the year
of our Lord One thousand eight hundred and fifty-three, in the seven-
teenth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Michael Leopold Parnell, Her
special licence that I, the said Michael Leopold Parnell, my executors,
administrators, and assigns, or such others as I, the said Michael
Leopold Parnell, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and law-
fully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF LOCKS," upon
the condition (amongst others) that I, the said Michael Leopold
Parnell, by an instrument in writing under my hand and seal, should.

page_text: particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Michael Leopold Parnell, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof (that is to say):
My improvements in the manufacture of locks consist of an im-
proved detector stop, of improved stops to resist or frustrate pressure
exerted on the bolt endwise, or in the direction of the bolt's motion,
and of an improved curtain for preventing the introduction of several.
picks at one time to act upon the levers or tumblers.
The mode of carrying out these improvements is set forth in the fol-
lowing description thereof, reference being had to the Drawings hereunto
annexed, and to the figures and letters marked thercon, observing that
the same letters denote the same parts in all the Figures.
"
Figure 1, represents my improvements applied to a door lock, the
cover plate and curtain being removed to show the "detector" portion
more clearly; and Figure 2, represents the same lock with the levers or
tumblers removed to shew the position and operation of the "end
pressure stop." a, is the box or case of the lock; b, the bolt; and c,
the stump; d, d, the tumblers, supported on a central axis, that is, an
axis e, situated between the two extremes, having the gating on one
side of the axis, and the detector springs upon the opposite side. d', d",.
are two inclines formed upon the inner end of the tumblers; and f, f,
are the detector springs acting upon the inclines. In the position of the
parts shewn in Figure 1, it will be seen that the detector springs act upon
the lower incline d', thereby tending to depress the opposite end of the
tumblers; but if one of the tumblers be overlifted by means of a pick
or false key the spring of that tumbler is brought to bear on the upper
incline d, thereby elevating the opposite end of the tumbler, and retain-
ing it in that position, so as to prevent the stump from entering the
gating 9, of the tumbler h, Figure 2, (shewn dotted in Figure 1, and
detached in Figures 3, and 4,) represents one kind of "end pressure stop"
which I employ. It turns upon an axis fixed to the casing of the lock.

page_text: (preferably the axis of the tumblers), and is pressed against the stump by
the tumblers, and in this position relieves the tumblers from all end
pressure, rising (by the action of the spring i,) only when the last
.tumbler is raised, so as then to permit the stump to enter the gating of
the tumbler. j, represents another kind of "end pressure stop;" it
consists of two arms 1, 2, turning upon a pin immediately above the
-bolt. The arm 1, in the position shewn in Figure 2, relieves the
tumblers from all end pressure, and it is raised by one of the tumblers
-acting upon the stud or pin k, on the stop to allow the bolts to recede;
but should it be overlifted the end 2, descends behind the back end
of the bolt and prevents it passing. When the bolt is shot out the
stop may be restored to the position shewn in Figure 2, by the action
of the tumbler upon the end 2, or by a spring. This stop may be
modified by suppressing the arm 2, and employing a spring to depress
the arm 1.
Another mode of frustrating the effect of end pressure upon the bolt
is shewn in Figure 5, and consists in cutting a false notch m, in all the
tumblers immediately behind the stump when the bolt is shot. The
.bolt is held out to its full extent by the yielding stop n, (or any other
convenient contrivance). Upon the application of pressure the stop n,
yields, and the bolt slightly recedes, but is stopped by the stump entering
the false notches m, in the tumblers. Figures 6, 7, 8, and 9, represent
my improved curtain; Figure 6, being a view of the front side; Figure 7,
a view of the opposite side; Figure 8, an elevation; and Figure 9, a
section; the improvement consisting in the addition a socket o, to the
curtain p, the said socket descending to the bottom of the lock, and
turning upon the ward q, surrounding the drill pin, (or in the case of
locks which lock from both sides) surrounding the hole which receives
the pin of the key.
Figures 10, 11, 12, and 18, represent one of my improved end
pressure stops applied to an ordinary cabinet tumbler lock. In this
application the stop is represented as acting within the outer chambers
of the tumblers. Figure 10, represents the lock with the face plate
and curtain removed; Figure 11, the lock with the tumblers removed,
to shew more clearly the action of the stop; and Figures 12, and 13,
shew the stop detached. I should observe, that the first and second of

page_text: the end pressure stops above described may be employed in the same
lock, as shewn in Figures 1, and 2.
Having thus described the nature of my Invention, and the manner
of carrying the same into effect, I claim in respect thereof the applica-
tion to tumbler or lever locks of the following parts:-
First, the improved detector stop, in which the tumblers or levers
turn upon au axis situated between the two ends of the levers, and
have two inclined planes formed upon their inner ends, upon which
inclines the springs act, as herein-before described.
Second, the end pressure stop turning upon an axis fixed to the case
of the lock (preferably upon the tumbler axis), and kept down by the
levers, as herein-before described.
Third, the end pressure stop (whether with one or two arms) turn-
ing upon a pin placed immediately above the tumblers, and raised by
the action of one of the tumblers, as herein-before described.
Fourth, the end pressure stop formed by cutting a false notch
through all the tumblers immediately behind the stump (when the
bolt is shot) to receive the stump so as to prevent the bolt receding
beyond the depth of the false notch, the bolt being retained in its
proper position by a yielding stop.
Lastly, the improved curtain, having a socket formed upon it, which
turns upon a cylindrical ward, and descends to the bottom of the lock,
the ward being concentric with the drill pin, or (in the case of locks
which lock from both sides) with the hole which receives the key
pin.
In witness whereof, I, the said Michael Leopold Parnell, have
hereunto set my hand and seal, this Eighth day of March,
..
in the year of our Lord One thousand eight hundred and fifty-
0
Witness,
JAMES MURDOCH.
M. L. PARNELL. (L.S.)