EFFECTS OF THE GREAT EXHIBITION OF 1851 IN IMPROVING ENGLISH LOCKS.
We have now to refer to the effects of the lock controversy. It was no
doubt annoying to be told, on good authority, that the machines on which
we so much prided ourselves were wrong in principle; and that our locks,
in order to afford the degree of security which are expected of such
contrivances, must be re-constructed. The grumbling with which the first
part of this proposition was received would alone have sufficed to lead
to a suspicion of its truth, if the large number of new locks that have
actually appeared had not confirmed it. Whether the second part of the
proposition has been fairly carried out, is a point which must now be
considered.
One of the first locks produced during or immediately after the lock
controversy was Mr. Parnell’s, to which the bold term of _patent
defiance lock_ is attached. This lock is said to depend for its security
on a mode of arrangement which may best be described in the inventor’s
own words: “Viewing the lock from its exterior, it presents nothing
remarkable; but, upon removing the plate, it will be seen that all
possible access to the mechanism with false or surreptitious keys is
effectually prevented by a solid cylinder of _hardened_ [?] brass, with
protecting wards extending the whole depth of the lock, and having in
the centre the aperture for the key, which fits to a mathematical nicety
so exact as to preclude the possibility of any second instrument being
used to open it.... This protecting cylinder must revolve with the key
to get to the works; and the moment it passes from the key-hole in going
round to lock or unlock, the solid portion moves into its place, and so
completely closes that aperture that the point of a pin, or a fine
steel-pen, has failed to be inserted between it and the outer plate or
cap, to say nothing of the utter hopelessness of perforating the metal.
“The cylinder or protecting cap, though it revolves by the action of the
key somewhat in the same way as the cylinder of the Bramah lock, appears
to be intended rather for closing or protecting the key-hole than for
governing the movements of the bolt. The internal arrangements of the
lock are as follow: Supposing the bolt to be shot, and to be about to be
unlocked, the key, by the time it has made about one-third of a
rotation, meets with a forcible resistance in the shape of an upright
spring-bolt or detector of strong steel acting on the revolving
cylinder. The key passes this detector, and arrives at the levers or
tumblers. In the bolt-stud which works in the slot of these tumblers
there is a small deep serrated notch on one side, corresponding to
similar notches on each of the tumblers; if, therefore, the bolt be
forced, these notches would lock into each other in a similar manner to
the catch on a ship’s windlass or a hoisting crane. There is also a
double-action tumbler-bolt, so adjusted, that if any of the tumblers be
overlifted, this little appendage becomes thrust down at one end into
the bolt of the lock, where it wedges all fast until the tumblers
become properly re-adjusted. The double-action tumbler-bolt also falls
into the lock-bolt when the latter is locked or shut, thereby imparting
an additional strength to the lock. The key has a power of expansion or
enlargement while turning in the lock; it meets with an eccentric plate
which draws out the bits somewhat; so that, at the moment of acting on
the tumblers, they protrude farther from the pipe of the key than when
the key entered the key-hole. The key is, in fact, larger when in than
when out of the lock. There is connected with the works of the lock a
‘detention-cap,’ so formed that, in the event of a false key being used,
a powerful bolt instantly locks into the revolving cylinder, and holds
fast the surreptitious instrument.” Such is, in substance, the account
which Mr. Parnell has given of his own lock. It must, however, be
stated, that the points of security or novelty claimed by Mr. Parnell
for his lock were patented by previous inventors. The revolving cylinder
or curtain was claimed by Mitchell and Lawton in the patent of 7th
March, 1815, as noticed at page 52 _ante_. The expanding key-bit was
claimed by Mr. Machin of Wolverhampton in 1827, as noticed at page 61,
and by Mr. Mackinnon (page 62); while the serrated notches in the
tumbler were used by many lock-makers long before the date of Mr.
Parnell’s patent. The detention-cap for catching and holding a false key
when put into the lock was also patented by Mitchell and Lawton, as
noticed at page 53 _ante_.
We come now to notice a lock lately invented by Mr. E. B. Denison (the
author of the _Rudimentary Treatise on Clocks_ in this series), which
has the merit of combining considerable novelty in construction with
security. After the details given in the two preceding chapters, it will
certainly be no small praise when we express our conviction that in the
present state of the art of lock-picking, this lock may be considered as
secure. Mr. Denison has furnished us with a description of his lock,
which we insert almost in his own words. Mr. Denison claims for this
lock the following advantages:--
1. That a very large and strong lock on this construction only requires
a very small key. 2. That no key is required to lock it, although it is
free from the inconvenience pertaining to spring-locks, viz. that the
door cannot be shut without locking itself. Moreover this lock is more
secure than any spring-lock can be. 3. That it cannot get out of order
from the usual causes of the tumblers sticking together or their springs
breaking, inasmuch as the action of the tumblers does not depend on any
thing but the key and the handle, and there are no tumbler-springs. 4.
That for the same reason, the parts of this lock do not require any
polishing or delicacy of execution. 5. That the key-hole being
completely closed by a curtain, except when the key is in, the lock is
protected from the effects of the atmosphere and dust entering at the
key-hole. 6. That this lock is secure against any known mode of picking;
the smallness of the key-hole prevents the insertion of any instrument
strong enough to open the lock by violence. 7. That this lock, from the
simplicity of its construction, admits of being made at small cost.
These objects are accomplished as follows:--In the large-sized locks,
such as would be used for safes and large doors, the tumblers T, fig.
51, are made of pieces of hoop-iron, 6 or 7 inches long and 1¹⁄₂ inch
wide: these tumblers are supported by and turn on a pin _a_, placed at
about the middle of their length; so that being balanced on the pin, or
nearly so, and having their separating plates P between them, which
cannot turn, the tumblers will stand in any position indifferently; and
in order to secure sufficient friction to keep them steady, one or more
of the separating plates P is bent a little, so as to act as a spring
when the cap of the lock is screwed down. The lock is shewn in fig. 51
as locked, the bolt B having been shot by the fantailed piece _f_ on the
handle, and the tumblers sent down, so that the stump _s_ cannot enter
their jaws by the other piece of the handle; and it is evident that the
handle cannot draw the bolt back again until the tumblers have all been
raised by the key to the proper position to allow the stump _s_ to enter
their jaws. It will be observed that in the position shewn in the
figure, the stump does not touch the tumblers; and consequently, so long
as the bolt is kept in the position represented, no pressure of the
stump against the tumblers can be felt, although by means of a false key
or pick-lock the tumblers be raised to any height. No implement,
however, can be pushed into the key-hole without first pressing in the
curtain K, which is held up against the cap of the lock by the two
spiral springs _c c_ on each side of the key-hole; and at the back of
the curtain there is a square plug _p_, which goes through a hole in the
back of the lock, and has a notch in it through which the bolt can pass
when the curtain is up, closing the key-hole, but at no other time. In
other words, the act of pushing in the key sends down the curtain plug,
the effect of which is to hold the bolt fast in the position in which
the stump cannot be made to touch the tumblers. If the proper key be
used and turned about half round to the right, it will bring the
tumblers to the proper height for the stump to pass. The key is then
taken out; for so long as it is in the lock, the bolt cannot be moved;
and then turning the handle to the right, the bolt is drawn and the door
opened.
[Illustration: fig. 51. Mr. Denison’s large lock.]
The handle H should be so made, that as soon as the fantailed piece _f_
has sent the bolt just clear of the tumblers, the other arm to the right
of H may begin to move the tumblers; but the fantail need not send the
stump above one-sixteenth of an inch beyond the tumblers; and the
curtain-plug and bolt must be so adjusted that the curtain cannot be
pushed in until the bolt is so far out that the stump is this
one-sixteenth of an inch beyond the tumblers. The curtain K need only be
a thin piece of steel, and the bolt B must be thick enough for the
curtain to go down just to the level of the thin plate P between the
bolt and the first tumbler T. The curtain-plug _p_ is made as long as
the key-hole and rather broader, and of the shape represented, partly
for the sake of steadiness in pushing in the curtain, and also for more
completely protecting the key-hole; for if an attempt be made to pick
the lock by drilling into the key-hole, the drill will pass into the
inside of the door and not into the inside of the lock.[10]
[10] Mr. Denison informs us that there is a further contrivance, which
he will explain privately to any persons who wish to manufacture these
locks, of which the object is, not to add any thing to the security of
the lock under ordinary circumstances, but to provide against the
unusual case of a very dexterous thief having occasional access to the
lock when open; in which case (but for some such further provision) he
might manage to construct a false key capable of opening the lock at
any other time, by a method which, for obvious reasons, it is not
advisable to publish.
It is true that iron safes have been made for some years in which any
number of large bolts are shot by a handle and then locked by a very
small key. But in such locks the key must be used in locking, and this
leads to certain objections, viz. the key must occasionally at least be
confided to some person whose duty it is to lock up the safe after the
owner has left the place; there is also the temptation to leave the key
in the lock, since it will be wanted in locking up; and thus there is
the danger of some dishonest person taking an impression of the key.
Besides this, the real strength and security of such safes is only that
due to the small lock which locks into the main bolt; whereas in Mr.
Denison’s lock the security and strength are those due to the lock
itself, with its large and strong tumblers, and other provisions
peculiar to its construction; and the key for a lock of the largest
size, which was lately exhibited at the Society of Arts by Messrs. S.
Mordan and Co., the makers, only weighs a little more than a quarter of
an ounce. It may be mentioned that for large locks the key may be solid,
although in the small ones it is more convenient to have a pipe-key, on
account of the different construction of the curtain.
[Illustration: fig. 52. Mr. Denison’s small lock.]
The arrangement of the small lock for drawers, &c. is somewhat different
from that of the large ones, and will be understood by referring to fig.
52. The action of the handle H on the bolt B and on the tumblers T is
sufficiently clear from the figure. The curtain in this case has no
plug, but is only a flat plate held up by a thin spring behind it, and
moving up and down on the drill-pin of the key, and kept from turning by
having one edge against the side of the lock. The bolt has a kind of
second stump, only coming up so high as to be able just to pass under
the corner of the curtain when it is up, but not able to pass when the
curtain is at all pressed down by any thing inserted in the key-hole. In
a drawer lock the key has only to be turned a quarter round in order to
raise the tumblers. In small locks, the friction of the tumbler-plates
is quite enough to keep them in any position, without putting the pin
in the middle so as to balance them, as in large locks with heavy
tumblers.
In the making of these locks the key must be made first, with proper
provisions to prevent the repetition of the same pattern; a kind of
pattern or model for locks of each size should be made; the tumblers put
on the pin with plates of the intended thickness between, and when
raised by the key to the proper height they should be clamped down; and
the jaws for the stump of the bolt may then be cut by a circular saw
moving in a slit in the model corresponding to the place of the stump.
The tumblers for large locks may be cut off from a strip of hoop-iron to
the proper lengths by a stamping cutter, giving them the proper circular
end, and a punch might at the same time make the pin-hole in the middle.
The tumblers for small locks should be stamped out of sheet brass or
iron.
It will thus be evident that from the general simplicity of
construction, and the small amount of finish required in the working
parts, this lock can be made at small cost. We may also add that this
lock is as creditable to the public spirit as to the mechanical skill of
the inventor; for the lock is not patented, patents being, in Mr.
Denison’s estimation, obstructions to the progress of science.
The next result of the “lock controversy” which we have to notice is the
production of not less than three improved locks by Messrs. Chubb. We
thought it our duty to invite the attention of this celebrated firm to
the preparation of this _Rudimentary Treatise_, and in answer to the
application of our publisher we received the following communication
from Messrs. Chubb, which we insert verbatim:--
“It will not be necessary to describe the lock as originally made, as a
description of it will be found in Mr. Chubb’s paper read before the
Institution of Civil Engineers.
“LOCK NO. 1.--The first of the improvements introduced consists of a
barrel, to which a circular curtain is attached, revolving round the
drill-pin in the lock; so that if any instrument is introduced to
attempt to pick it, the curtain immediately closes up the key-hole, and
prevents the introduction of any auxiliary instruments, there being
several required in action at once to produce any effect.
“If by any means these several instruments can be introduced
simultaneously, the barrel keeps them all confined in a very small
space, preventing their expansion, and renders it impossible to work
them independently of each other; therefore they are of no avail, being
incapable of acting as more than a single pick, which is perfectly
useless. The barrel and curtain have each been previously used
_separately_ in locks, but until patented by Mr. De la Fons in 1846 they
had not been used _in combination_. Neither of them, used separately, is
of much use, but when combined they afford a very great security. Locks
have been, and still are shewn, containing either the barrel or curtain
_singly_, and as these have been picked, it has been asserted that the
improvement now introduced in Chubb’s lock is equally insecure; but a
slight examination of the difference in their construction will prove
the contrary. Mr. Chubb has purchased the patent-right of this part of
Mr. De la Fons’ invention, and applies it to all his locks.
“LOCK NO. 2.--The next improvement, recently patented by Mr. Chubb, is
based upon the assumption that there may be a possibility of overcoming
the security of the barrel and curtain as already described (although
this assumption is not in the slightest degree admitted), and consists
in applying what is called a ‘tumbler-bolt,’ working on a hinge
connected with the main bolt. The web of the key does not in any case
touch the main bolt in unlocking, but acts only on the tumbler-bolt. All
the tumblers must first be lifted, each to its proper position, before
the tumbler-bolt will act. Should any pressure be applied to either bolt
before the tumblers are all at their exact position, the effect would be
to throw the bolts out of gear, and thus effectually to stop the stump
of the main bolt from passing through the racks of the tumblers. None of
the many plans of picking which have been suggested, such as smoked
key-blanks, thin key-bits, &c., would be of the least avail against a
lock made on this principle. Different kinds of detectors may be applied
to these locks. It is submitted that this lock, retaining all the
simplicity and durability which have distinguished Chubb’s lock for so
many years, and combining with them these important improvements,
affords a complete security against all surreptitious attempts of any
nature. Locks on the same principle are being made on the permutation
plan, with any number of tumblers, and any number of changes in
combination that may be desired.
“It has been suggested that the ‘detector,’ instead of giving additional
security to Chubb’s lock, affords a partial guidance to a person
attempting to pick it. This objection holds good to a certain extent in
these locks as originally made, in which all the tumblers had an _equal_
bearing against the detector-stump; but in the locks as now constructed
this objection is entirely obviated, by giving the tumblers an _unequal_
bearing, whereby, if an operator feels the obstruction of the
detector-stump, he cannot tell whether the tumbler which he is lifting
is raised too high, or not high enough.
“LOCK NO. 3.--For banks, Mr. Chubb has introduced what he particularly
calls his ‘bank lock.’ It contains a barrel with a series of curtains.
While the key-hole is open, all access to the tumblers from the key-hole
is completely cut off by two sliding pieces of solid metal, which fit
closely on either side of the barrel. These pieces are acted upon by an
eccentric motion, so that when the key is applied to the lock, and
turned in it, the key-hole is shut up by the revolution of the curtains,
and then only do the sliding pieces of metal move aside to allow the key
to act upon the tumblers. These pieces return to their position when the
key has passed; therefore, while the key is lifting the tumblers, all
communication is cut off from the exterior of the lock by these sliding
pieces and the series of curtains. The bolt is made in two pieces, the
main bolt never being in contact with the key, which acts only on the
talon-bolt, and by it transmits the motion to the main bolt. After the
action of locking, the talon-bolt is partly repelled, and a lever or
‘dog’ connected with it locks into a series of combinations arranged
upon the front parts of the tumblers, and holds them securely down, so
that none of them can be lifted in the least degree until the talon-bolt
is thrown forward to release them, If, therefore, any pressure be
applied to this talon-bolt, to endeavour by its help to ascertain the
combinations of the tumblers, it will only the more tightly lock them
down, and render the attempt ineffectual. By another contrivance it is
rendered impracticable to move a pick or picks round in the lock more
than a small distance, unless the tumblers could previously be all
lifted to their right positions, which can only be done by the right
key. Should one or more of the tumblers be surreptitiously raised by any
possible means, they cannot be detained in this uplifted position, for
the action of turning back the pick to try to raise another tumbler sets
in motion a lever which allows the tumblers already raised to drop to
their former position, leaving the operator just as far from the
attainment of his object as at the outset.”
Such is the statement with which Messrs. Chubb have favoured us
respecting their three new locks. We are willing to admit the
enterprising spirit which has led to their production, and the ingenuity
which has been bestowed on their construction; but whether they mark a
step in advance in the art of lock-making may perhaps admit of doubt.
With respect to the lock No. 1, we would remark, that locks with the
barrel and curtain combined were made by Mr. Aubin of Wolverhampton in
1833, and that a specimen of such a lock was exhibited on his stand of
locks in the Great Exhibition. Locks with the combined barrel and
curtain were also made and sold by Mr. Jones of Newark, N.J., as stated
at p. 104.
With respect to the lock No. 2, the object of the _tumbler-bolt_ is
evidently intended to produce the same effect as the _movable stump_ in
Mr. Hobbs’s protector-lock, fig. 47, page 100; but with greater
complexity in the construction, there is less efficiency in the action
of this part of Mr. Chubb’s lock as compared with that of Mr. Hobbs,
inasmuch as a pressure of the stump against the tumblers, corresponding
with the strength of the spring which holds the bolt in its place, can
always be produced, thereby giving friction, and affording indication as
to which tumbler it is that is in tight contact with the stump.
With respect to the barrel and curtains of lock No. 3, and all similar
contrivances, the object of which is said to be to prevent the entrance
into the key-hole of all instruments except the proper key, we would
offer the self-evident remark, that the same aperture which admits the
key will also admit some other instrument. In the case of Mr. Chubb’s
“bank-lock,” it may be questioned whether the revolving curtain, &c.
give it any advantage over the other locks already referred to which are
furnished with similar contrivances. The effect of the _talon-bolt_ in
this lock appears to be the same as that of the false notches, namely,
to hold the tumblers in the position in which they were placed when the
pressure was applied. Hence, a pressure applied to the talon-bolt
affects the parts which come in contact with the key in the act of
locking and unlocking; and this circumstance brings the lock under the
application of the principle stated at page 99, and thus, if this
principle be admitted, may render the security of the lock somewhat
questionable.
Various other locks have been brought out since the date of the “lock
controversy” in the year 1851. We would gladly notice them all, did they
shew novelty of design and mark an advance in the art of the locksmith.
We must, however, admire the ingenuity with which Mr. Hobbs’s movable
stump has been more or less adopted; but in the attempts to imitate it
the objection has not been removed, that it is possible to produce on
the tumblers a pressure or friction equal to the strength of the spring
which holds the tumblers down.
There is, however, a lock which has lately been introduced to the
public, which calls for special notice, on account of the high honours
which have been bestowed upon it. We refer to the prize lock of the
Society of Arts, London, the invention of Mr. H. J. Saxby of Sheerness,
who has received the Society’s medal and the sum of ten guineas as the
reward of his ingenuity. The interior of this lock consists of a
cylinder with four pins or slides radiating from the centre, and pressed
into the key-hole by means of spiral springs. The pins project beyond
the periphery of the wheel or cylinder, and into slots in a ring which
is affixed to the case of the lock, thereby preventing the cylinder from
being turned. On each pin is a notch, so placed that when the proper key
is inserted into the key-hole, the notches on the several pins will be
brought into a position such as will allow the cylinder to turn. The
turning of the cylinder in this, as in the Bramah lock, shoots the bolt.
A lock on precisely the same principle, but more secure in its
construction, was described by Mr. Hobbs in a paper read by him before
the Society of Arts in January 1852, when diagrams illustrative of the
same were exhibited. This paper was not reported at any length in the
journal of the Society’s proceedings; but the same paper was read by Mr.
Hobbs, March 1, 1852, before the Liverpool Polytechnic Society, and a
full report thereof, and a description of the lock in question, is given
in the “Transactions” of that Society, from September 1849 to December
1852 (8vo, Liverpool, 1853). This lock is no other than the Yale lock
already noticed at page 83, and is thus described at page 196 of the
“Transactions:”
“Another description of cylinder-lock was invented, a few years since,
by a Mr. Yale of the State of New York, U.S.A.
“The Yale lock has two cylinders, one working within the other; and they
are held together by a series of pins reaching through the cylinders
into the key-hole, which is in the centre. On the back of the inner
cylinder is a pin that fits into a slot in the bolt, and moves it as the
cylinder is turned. The pins that hold the cylinders together and
prevent the inner one from turning, are cut in two at different lengths.
The key is so made, that by inserting it into the key-hole the pins are
moved, so that the joint in the pins meets the joint between the
cylinders, and allows the inner one to be turned. But, as with the
slides of the Bramah lock, should any one of the pins be pushed too far,
the cylinder is held quite as firmly as though it had not been touched.
Some of these locks have been made with as many as forty pins; and to a
person unacquainted with the principles on which locks are picked, they
would seem to present an insurmountable barrier.
“Figure 1[11] represents the case of the lock containing the bolt A,
having a groove B, to receive the pin C on the cylinder. Figure 2 shews
the cap or top-plate of the lock, and the cylinders; D D is the outer
cylinder, that is stationary, being fastened to the plate; E E the inner
or moving cylinder; F F the four rows of pins, being cut in two at
different lengths, and reaching through the cylinders into the key-hole;
G G are the springs that press the pins to their places; C the pin that
fits into the groove and moves the bolt. Figure 3 is an end view of the
key, shewing four grooves. Figure 4 is a side view, shewing the
irregular surface of the grooves by which the pins are adjusted.
[11] This and the following figures refer to the diagrams exhibited by
Mr. Hobbs.
“For the purpose of picking the lock, an instrument is made that will
fit between two of the pins; to that is attached a lever and weight,
thereby getting a pressure on the cylinder and causing the pins to bind;
then with another instrument the pins are felt, and as they are found to
bind, they are pressed in until they are relieved (as they will be when
the joint comes to the right place), thereby easily opening the lock.
There is a great similarity in the operation and security of this and
the lock manufactured by Mr. Cotterill of Birmingham.”
In the _Society of Arts Journal_ for the 24th June, 1853, is a letter
from Mr. Hobbs on the subject of the prize lock, which, it appears, he
picked, “in the presence of parties connected with the Society, in the
short space of three minutes.”