Year: 1887

page_text: Date of Application, 27th Apr., 1887
Complete Left, 26th Jan., 1888
Complete Accepted, 2nd Mar., 1888
I, STUART CARADOO MUNRO, of No. 25 York Street, Baker Street, in the County
of Middlesex, Gentleman, do hereby declare the nature of this Invention to be as
follows:-
:―
This Invention relates to apparatus to be employed in combination with the ordinary
locks used in safes and is intended to prevent the opening of the same by means of a
duplicate key.
The apparatus works somewhat on the principle of the well known letter lock and
consists of a catch fixed on the inside of the keyhole cover in such manner that when
the cover is closed, an arm or finger projecting through the outer plate of the door of
the safe will engage therewith and prevent the cover from being displaced.
The projecting arm is attached to a vertical rod which can be moved up or down
inside the door plate, the upward motion serving to disconnect the arm from the catch
on the keyhole cover.
On the top of the vertical rod is a cross bar provided with a series (say four) of
vertical prongs or fingers, and above this is a corresponding series of discs having
cam grooves on their surfaces.
These discs are mounted on studs passing through the outer door plate and on the
outer ends of these studs, dial plates either figured or lettered are adjustably fixed in
such manner that when they are turned round so as to correspond with a previously
determined code word or number, the ends of the slots on the inner set of discs will
be opposite the ends of the prongs or fingers on the vertical bar and allow the studs
or pins thereon to enter the said cam, grooves or slots, thus allowing the bar to be
pushed upwards and the keyhole cover released. The slots in the discs are curved
so that as soon as the door is opened, the order of the numbers on the outer dials will
be changed and the same will have to be re-set before the safe can again be
opened.
In order to prevent the code word or number from being discovered by tampering
with each dial or disc separately, a metal strip is mounted horizontally underneath the
entire series so as to cover the openings of the slots or cam grooves. The strip is

page_text: maintained in position beneath the openings by cams on the discs so arranged as to
leave the supports of the strip free when the discs are in the proper order for opening,
in which case the strip will be removed from its position opposite the ends of the slots
by means of spiral or other suitable springs. As each one of the cams on the discs is
capable of retaining the spring in position, it follows that the accidental placing of one
of the dises in its proper position for opening, will not afford any clue towards the
discovery of the code word or number.
In combination with the metal strip I employ one or more alarm bells which will be
sounded in the event of any one attempting to tamper with the lock.
DL:
3 1
2
1087
HUGHES, ELI & HUGHES,
76, Chancery Lane, London, W.C.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Method of and Apparatus for Preventing the Fraudulent
Opening of Safes.
I, STUART CARADOC MUNRO, of No. 25 York Street, Baker Street, in the County
of Middlesex, Gentleman, 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 apparatus be employed in combination with the ordinary
locks used in safes and is intended to prevent the opening of same by means of a
duplicate key.
In the accompanying drawings Figure 1 represents outside or front view of the door
of a safe. Figure 2 an inside view thereof. Figure 3 an edge or side view, and
Figures 4, 5 and 6, details hereinafter described.
a represents a series of dises numbered round their margins and capable of being
turned round on studs a¹ until any number predetermined upon shall coincide with a
pointer or index a². The studs or axes a pass through the door plate and carry discs b
on the faces of which are formed grooves or channels 6. A series of bent pins c are
fixed to a horizontal plate & which is attached to a vertical bar d.
The plate d is slotted at d and screwed studs d³ pass through the slots into the door
plate so as to keep the plate d in horizontal contact therewith and yet leave it free to
slide up and down This sliding motion is imparted by a lever ffixed to the spindle
of the handle, the said lever engaging with pins on the vertical bar d'. g is the

page_text: keyhole guard which is hinged at g', a staple g² fixed to the guard passing through the
keyhole where it is secured by the arm of a lever which passes through the slot
of the staple. The lever his fulcrummed at hand is slotted to receive a pin h³
projecting from the bar d'. Before proceeding further with the description of the
parts, I will explain the action of those already described.
Supposing that it is required to open the safe, this cannot be done until the keyhole
is exposed. To effect this the discs a are turned until the predetermined letters or
figures thereon have arrived opposite their index marks. When in this position the
whole of the cam grooves in the discs bare arranged as shewn in Figure 2, the
openings or entrances to the grooves being opposite the ends of the pins c. If
the handle be now turned, the lever will raise the bar d' the plate d and the pins c
the bent ends c¹ of which will enter the grooves and continuing to pass upwards
will turn round the discs b. During this upward motion the pins ³ will have with-
drawn the lever arm h' from the staple of the keyhole guard leaving the latter free.
The safe can now be opened and when closed again the pins e' will not pass out by the
grooves but by the grooves 62 which form a continuation thereof so that a
continuous rotary motion is imparted to the discs. If this were not the case, the
withdrawal of the pins from the grooves would leave the discs in the original
position and so afford no safeguard, but by turning the handle sharply
backwards a certain amount of impotus can be imparted to the discs which will
continue to revolve indefinitely after the pins have passed down out of contact
therewith.
In order to enable the person entrusted with the control of the safe to vary the
number or keyword at pleasure, the studs a¹ on which the dises bare mounted are
formed in the shape of small pinions the teeth of which correspond with the letters or
figures on the discs a and the holes in the centres of the discs bare indented to fit
onto these teeth so that if there are twelve numbers on the dials each or any of the
discs can be turned round a twelfth of a revolution, and so every variety of
combination afforded by the numbers on the discs can be made use of.
In order to prevent the discovery of the keyword or number by turning the handle
and raising the pins c until they come into contact with the edges of the discs b and
then turning the latter round in contact therewith until the break in the periphery can
be felt, I make use of a device consisting of a light metal angle bar i which is supported
in links jattached to each end of a plate k, this plate being pivotted at k in bearings k²
fixed to the door. On the axes af of the discs a are heart shaped locking pieces
which keep the bark rigid and only permit it to move when the pointed ends of the
cams are in the position shewn in the drawing.
Figures 5 and 6 are details of the edge and underside of one of the locking pieces,
what is meant by underside being the side in contact with the plate k. It will be
seen that on this underside is a boss or enlargement extending only half way round
the axis, the flat side of the boss being at right angles to the longer axis of the locking
piece.
When in the position shewn in the drawings, Figures 2 and 3, the half bosses /
bear against the plate k on the upper side of its rocking centres k¹ and thus if there is
a little play allowed between the bosses and the discs b, the lower edge of the plate
can move away from the discs, but if one of the pieces I be so turned that its half
boss projects ever so little below the centre line k k¹, then the plate k cannot rock
as its motion is gyrosed on both sides of its working centre.
Tho action of the parts is as follows:
Supposing the plate k to be free to move as shewn in the drawing; as the pins e
ascend they encounter the bar i which they raise, the bar turning partially round on
its axis and this movement coupled with the slight outward movement which is
permitted to the plate k, enables the pins e to pass the bar i and enter the grooves bl
in the discs b.
เ
Should however the plate & be locked by one or more of the pieces consequent on
the non-adjustment of the dials a, the pins c will not be able to push away the bar i
sufficiently to pass the same but will continue to raise it until it reaches the lower

page_text: edges of the discs b. Contact between the discs b and the pins c is thus prevented.
and if the dials a be revolved with a view to finding out the exact position of the
entrance to the groove b' by the sense of touch, the smooth surface of the bar i will
afford so little resistance to the motion of the disc oven where the edge of the latter is
broken by the opening of the groove that it will be impossible to detect the position
of the latter.
Although I have illustrated the best method I am acquainted with of carrying my
Invention into practice, it must be understood that I do not confine myself to the
precise details herein shewn as to the number, configuration or arrangement of parts,
as the same may be varied, but what I consider novel and original and therefore
claim, is:-
1. In apparatus such as described, the combination of a series of discs having
letters or figures marked thereon with a second series of discs having cam grooves
formed in the faces thereof substantially as specified.
2. The combination with a series of discs having cam grooves on the faces thereof of
a series of pins bent or hooked at their ends attached to a bar capable of being
moved vertically upwards and downwards from the outside of the safe substantially as
specified.
3. The combination with a series of grooved discs and pins for operating the same
of a lever for securing the keyhole guard substantially as specified.
4. The combination with a series of grooved discs of a swing supported bar such
as for covering the edges of the grooves substantially as specified.
5. The combination with a series of grooved discs of a har such as i supported
by a rocking bark the movement of which is dependent on the position of one
two or more plates 7 substantially as specified and illustrated in the accompanying
drawings.
1 A
1
1000
HUGHES, ELI & HUGHES,
76, Chancory Lane, London, W.C.,
Agents for the Applicant.