IMPROVEMENTS IN LOCKS.
Year: 1853

page_text: LETTERS PATENT to William Choppin, of the City of London.
Lock-maker, for the Invention of "IMPROVEMENTS IN LOCKS.".
PROVISIONAL SPECIFICATION left by the said William Choppin
at the Office of the Commissioners of Patents, with his Petition,
on the 11th February 1853.
I, WILLIAM CHOPPIN, of the City of London, Lock-maker, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN LOCKS"
to be as follows:-
The object of the first part of my improvements is to detect tam-.
pering with a lock by means of a false or wrong key. The principle of
this part of my Invention is applicable to single shot locks, and consists
in the use of a peculiar lever, which I call a "double paul," so acting
as to hold or detain a false key, and not permit of its extraction. The
double paul or lever is fixed to the bolt of the lock. The key is
inserted through a disc or circular plate. imoving with it, and on the
inside of this disc or plate there is another smaller disc perforated
in part like the first one for the admission of the key, and having a

page_text: notch or series of notches into which the paul is to drop. On the
large circular plate there is a small nib or projection, which, when
the key turns the disc or plate round, acts on the double paul, causing
one end of the said lever or double paul to catch or drop into the
notches on the inner disc, and on the completion of the revolution of
the key stops on the paul, which prevents its turning further, whether
in locking or unlocking. For example, in locking both discs turn with
it; the nib or projecting part having released one end of the double
paul is brought by the revolution to the opposite end of the paul,
which drops into the notches on the inner dise, so that this nib or
projecting part alternately raises and depresses each end of the paul.
The Invention may be carried into effect by using one plate instead
of two, in which case the paul has hooks instead of points, and a
projection on the disc in turning pushes up each end of the paul
alternately. The simplest manner of arranging the plate or plates is.
by placing them on a barrel which the key enters when passing into
the lock, so that the plates or plate turn with the key.
My second improvement in locks has reference to that description of
lock in which there are two or more shots, that is, when the bolt is
projected by two or more revolutions of the key, and the objects, are,
1st, to cause different parts of the key to act on different tumblers at
each shot, or different parts of the same tumblers; 2nd, to prevent
a key which has turned one or more of the shots in one direction from
turning them back in the other direction, unless it has first turned every
succeeding shot in the original direction. The tumblers in this lock
are placed in a box which is attached to the bolt; a spring in the
interior of this box over the tumblers acts upon them when moved by
the key. A stop piece is affixed to the plate of the lock which these
tumblers must pass, the tumblers having openings to correspond with
this stop piece. For example, when the key makes its first revolution
some of the tumblers will be raised so as to pass the stop piece, and
the bolt will make one shot; the tumblers then fall again.. In the
second revolution the key raises other tumblers, and may also (if
desired) be made to raise again the tumblers which had been raised
before. The tumblers thus raised pass the stop piece, and a second

page_text: shot is made, when the tumblers fall again as before. The same process
takes place at each succeeding revolution until the whole of the shots
are made, and the locking or unlocking completed. In unlocking tlie
same operations take place in reversed- order, and the whole series of
the shots must be made either in locking or unlocking in one direction
before they can be made in a contrary direction. A double paul or
lever is placed on the plate of the lock, which falls into notches cut in
the bolt. In locking, on the first shot being made, the paul falls into a
notch in the bolt, and thus prevents unlocking until the whole of the
shots are made. In making the last shot a projection on the bolt
forces up the end of the paul which has been in operation during the
locking, thereby bringing down the other end to act in unlocking.. In
like manner in the last shot of the unlocking the same projection sets
the paul to act again in the unlocking. When it is desired that the
false key should be detained in the lock until the whole locking or
unlocking is completed a sliding plate attached to and moving with
the bolt, having two keyholes in it, is affixed. It should be mentioned
that a spring acts upon the paul above alluded to. Instead of making
the tumblers move in a box, I can fix them to a bolt by a pin passing
through one end of them, leaving them to be operated upon by the key
at the other end; these come into operation in the second shot, and
only in the unlocking. They are acted on by a spring, which presses
them down until raised by the key in unlocking. There are deep
openings in the edges of the tumblers at the ends raised by the key, so
that when the tumblers are raised to the proper height by the key they
slide up an inclined stop fixed on the plate of the lock, and remain in
that position until the lock is locked, when the tumblers, advancing
with the bolt, fall down again from the incline, and stop the bolt from
being unlocked until they are again raised by the key. This operation
may be improved by making, the openings in the edges of the tumblers
different from each other in their direction, so that' different tumblers
would be raised to different heights. I propose that, in addition to
these tumblers, another set should be fixed to the plate of the lock
to operate in the common way; and in these, as in all the tumblers used
in these locks, I would make false notches, which add to the difficulty
in nicking the lock.

page_text: My third improvement is, where two locks are used in connexion
with each other on the same plate; & the object of this improvement
is to prevent a key from opening one lock unless the other has also
being unlocked, and to cover the keyhole of one until opened by the
unlocking, of the other lock. The first lock to be, opened I call A,
and the second B. A paul or lever is fixed on the plate of the locks,
acted upon by a spring. In locking A, (when B, is locked,) a pro-
jection on the bolt of A, raises the paul at one end, and the spring
presses the paul down upon the other end of the bolt of A; and if the
bolt of B, is locked, the paul acting on the bolt of A, prevents A, when,
unlocked from being relocked until B, is unlocked. In unlocking B,
a projection on the bolt, of it acts upon the upper side of the paul, and
raises the end that prevented the locking of A, by pressing down the
other end, and this continues, until B, and A, are again locked. The
paul does not act at all if B, is unlocked. To the bolt of. A, a plate a
is attached which covers the keyhole of B, when A, is locked, and
which may also be made to cover the keyhole' of A, in part, when A, is
unlocked with key in it.. The action of this lock is as follows:
Suppose the key of A, to be introduced when both locks are locked,
A, is then unlocked, and the paul falls into, a notch in the bolt of A,
and prevents its being. relocked: The withdrawal of the bolt. of A,
moves the plate off the keyhole of B. The key of B, is then introduced,
and B, unlocked, and in. this unlocking the bolt of B, acts on the paul,
and releases the bolt of A, from it. Both locks may then be succes
sively, relocked, but if it desired to leave B, unlocked, and to use A,
without the check of the paul, the key of B, is taken out without
relocking B; .A, can then be locked and imlocked at pleasure. A, may
or may not fasten the door. The lock of A, may be made to fasten the
door, but when this is the case. the sliding plate cannot be made to
cover the keyhole of A, without the inconvenience of detaining the the
key in the door when it is locked.
It must be understood that I make no claim to any improvement in the
tumblers of locks; I use those already known, and I reserve the right
to vary the details, of arrangement, but substantially my Invention is
herein-before described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Choppin in the Great Seal Patent Office,
on the 11th August 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
WILLIAM CHOPPIN, of the City of London, Lockmaker, send greeting.
'WHEREAS Her 'most Excellent Majesty Queen Victoria, by Her.
Letters Patent, bearing date the Eleventh day of February, in the year.
of our Lord One thousand eight hundred and fifty-three, in the six-
teenth year of Her reign, did for Herself, Her heirs' and 'successors,
give and grant unto me, the said William Choppin; Her special licence;
that T, the said William Choppin, my executors, administrators, and
assigns, or such others as I, the said William Choppin, 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 lawfully might make, use, exercise, 'and:
vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention of "IMPROVE-
MENTS IN LOCKS," upon the condition (amongst others) that I, the said.
William Choppin, by an instrument in writing-under my hand and.
seal, should particularly describe and ascertain the nature of the said In-
vention, 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 William Choppin; do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement::
The object of the first part of my improvements is to detect" tam-
pering with a
lock by means of a false key. This improvement is:
applicable to single shot locks, or for those in which the key makes
only one revolution, and consists of a peculiar lever, which term a
double paul," and a circular plate, having a portion of its periphery
cut or notched like the teeth of a saw; these act so as to hold or detain
a false key, and prevent its withdrawal.

page_text: Figure 1, shows this improvement applied to an ordinary tumbler
lock. A, is a thin metal plate, to which is screwed the serrated dise B.
C, is a small nib or stop which acts on the double paul D; a spring E,
presses on the paul, keeping it in contact with the disc B. (The lines
of these parts have been drawn "full" as if the materials were trans-
parent.) The bolt F, is represented thrown back or unlocked; when
the key is inserted and turned it carries with it the plate A, the double
paul D, travelling over the notches; when the bolt is shot the nib or
stop C, is pressing against the opposite side of the paul D, as shewn at
Figure 2; thus it serves alternately to raise and depress the paul. In
a lock of this construction the key cannot be partly turned round, then
turned back and withdrawn; thus, if a quarter of a revolution be made
with the key, the paul acting against the teeth of the disc B, will
prevent its withdrawal until the complete revolution is made; so also if
any attempt be made with a false key it will be detained in the lock,
unless the complete revolution can be made. Figures 3, 4, represent
a modification of this improvement. In this case the notched disc B,
is a single plate, and the ends of the double paul D, are hooked, as
shewn in the Figures, the action being similar to the foregoing.
Figure 3, represents the bolt thrown back. Figure 4, the bolt shot or
locked. The projection C', lifts the ends of the paul alternately.
The next part of my improvements relates to that class of locks
in which the bolt is projected by two or more revolutions of the
key or "shots," and the object is to prevent a key which has turned
one or more of the shots in one direction from turning them back in
the other direction, unless the whole of the shots have been made
in the original direction. Figures 5, 6, 7, represent a lock of this
construction. The tumblers of this lock A, Figure 5; are placed
in a box attached to the bolt B. C, is a steel spring cut through
a portion of its length into as many parts as there are tumblers,
forming a separate spring to each tumbler, and acting upon them when
moved by the key. D, is a stop piece or stump affixed to the back
plate of the lock; the tumblers have openings cut in them to allow of
their passing the stop. At one revolution of the key the tumblers are
lifted and the bolt carried forward one shot, the stop being now in the

page_text: notch D'; at the next revolution of the key the tumblers must be lifted
higher than before, distinct portions of the key being brought into
action for this purpose; the tumblers now pass the stop through the
space D, and fall into the notch D, when the lock is double shot.
In unlocking the same operation takes place in reversed order, and
both shots must be made before the bolt can be thrown back. This is
effected by means of the double paul E, which falls into notches E'; E",
cut in the bolt B, Figures 5, 6. In locking, the paul falls into the
notch E', as shown at Figure 6; and thus prevents the return of the
bolt; upon the next revolution of the key the projecting nib F, on the
bolt raises the paul, throwing it back to the position shown at Figure 7,
ready to act in the unlocking as before. The spring G, maintains a
slight pressure of the paul on the bolt B. If it be desired to detain a.
false key in the lock a plate H; Figures 6, 7, is secured to the bolt or
tumbler box by screws, and thus travels with the bolt; this plate has a
double keyhole and slot cut in it, as shown in the Drawing. Supposing
a false key to have passed one set of tumblers, and thus effected one.
shot of the bolt, the key will be midway between the keyholes in the
plate H, as shown at I, Figure 6; the bolt being securely held by the
paul, the key cannot be withdrawn. Figure 7; represents the bolt
completely shot, and the keyhole of the plate H, opposite tlie true key-
hole, Figure 5. In the foregoing I have referred only to a double shot
lock, but I do not confine myself to this number of shots, as the.
improvements may be applied to locks having any other number of
shots, and bringing different tumblers into operation at each shot.
Instead of making the tumblers move in a box, as above described, I
propose, in some cases, to fix them to the bolt by a pin passing through.
one end of them, causing them to be operated upon by the key at the
other end, and only at the second shot in unlocking. This improve-
ment is shown by Figures 8, 9. A, is the bolt; C, the tumblers;"
D, a spring which presses down the tumblers until they are raised by.
the key in unlocking; E, the stop piece or stump fixed to the back
plate of the lock; this is inclined so that when the tumblers are
raised to the proper height by the key they slide up the stop and
remain in that position until the bolt is shot by the key, when the

page_text: tumblers advancing with the bolt fall down the incline, and prevent
the bolt from being unlocked until the tumblers are again raised by
the key.'
Figure 8, represents the lock with the bolt thrown back, and the
tumblers resting on the stop. Figure 9, shows the position of the
various parts with the bolt shot; F, is a double paul, the action of
which is the same as before described, and shown by Figures 5, 6, 7.
The above lock may be made with two sets of. tumblers, fixed to the
bolt by pins, and placed at the sides of two stumps or stop pieces. At
the first revolution of the key the set of tumblers to the right are
lifted and pass the first stump, the double paul being in the position
shown by Figure 6; at the next revolution the other set of tumblers-
are brought into action and pass the second stump.
The next part of my improvements is, where two locks are.used in
conjunction with each other, and affixed to one plate, and the object is
to prevent a key from opening one lock unless the other has been
unlocked, and also to cover the keyhole of one lock while the other
remains locked. Figures 10, 11, represent a lock of this construction;
the bolt a, of the lock B, is represented as unlocked, and the proper.
key will not relock it, by reason of the pawl b, pressing. against the
"notch "c, in the bolt by means of the springs d, and d. In order to
release the paul the bolt of the lock A, must be thrown back, when
the angular projecting piece of metal e, on the bolt of A, will depress
the paul, throwing it in the position shewn by Figure 11; the bolt of
the lock B, is now free, and will continue so until both locks are again
locked, when the paul will fall into the notch c, on unlocking B. The
action of the sliding plate f, is to cover the keyhole of A, when B,
is locked, or it may cover the keyhole of B, when unlocked.
- Figures 12, 13, represent a combination lock differing somewhat in
its action from the one above described. A, and B, are two locks
secured to one plate. The bolt of the lock A, may be thrown back by
the key when B, is in the position shown at Figure 12, but cannot be
thrown forward in consequence of the bolt being retained by a catch.
screwed to the bolt of the lock B. g, is a stud fixed to the back-
plate; h, a stud on the bolt of A i, a catch secured to the lock B.

page_text: When the lock A, is thrown back the catch i, falls on the stud h,
thereby retaining the lock A, in that position until the bolt is projected
by locking B, the bolt of which, when the key is turned, presses against
the end of the bolt of A; the catch i, slides up the stud g, where it
is held in the position shown at Figure 13. The lock A, cannot now
be unlocked until the bolt of B, is withdrawn by unlocking B; thus
this kind of lock can be locked with one key, but requires both keys
to unlock it. The paul k, retains the lock B, when thrown back, the
projection piece V, releasing it when the lock A, is thrown back. When
B, is locked, the keyhole of A, is covered by the plate m. When B,
is unlocked it cannot be relocked, by reason of the paul k, catching
in the bolt until A, is unlocked.
Having described the nature of my Invention, and the manner in
which the same is to be carried into effect, I would have it understood
that I do not confine myself to the precise details herein-before set-
forth, as they may be varied to some extent without departing from the
peculiar principle of my Invention. But I claim the construction and
use of the double paul in locks, as herein-before described and shown,
and I claim the construction of locks in the manner and on the prin-
ciple herein-before described, and shown by the Drawings annexed.
In witness whereof, I, the said William Choppin, have hereunto
set my hand and seal, this Eleventh day of August, One
thousand eight hundred and fifty-three.
W* CHOPPIN. (L.S.)