CHAPTER VII.AMERICAN LOCKS.

fig. 33. Bramah’s first model.

The lock is supposed to be lying flat, with the boltBhalf-shot. Ranged somewhat diagonally are six levers, turning on a horizontal joint or pivot atA, each lever having a slight extent of vertical motion independent of the others. Eachlever rests on a separate spring of sufficient strength to sustain its weight, or, if depressed by a superior force, to restore it to its proper position when the force is withdrawn.Fis a curved piece of metal, pierced with six grooves or passages; these grooves are exactly equal in width to the thickness of the levers, but are of sufficient depth to allow the levers a free motion in a perpendicular direction. The ends of the levers are inserted in these grooves, and have this freedom of motion, whether lifted by the elastic power of the springs or depressed by a weight from above. In the boltBis a notch to receive a peculiarly-shaped lever, which shoots or withdraws the bolt according as it traverses to the right or the left. This lever, the six long levers, the springs beneath them, the bent pieceF, and the pivot, all alike are fixed to a circular platformP, which turns on a centre; so that if any force can make this platform turn partially round, the bolt must be shot or unshot by the lever which works in the notch. The six long leversare the contrivances whereby the platform shallnotbe allowed to turn until the proper moving agent (the key) shall have been applied, the platepbeing one of the assistants in this obstruction. This plate, which is hollow underneath, has six notches in one of its edges; the points of the levers catch into these notches; and while so caught, the levers cannot move horizontally, and all the machinery is at a stand-still. To enable the key to set the mechanism in action, other contrivances are necessary. Each lever has a notch at its extreme end, and the six are notched very irregularly in respect one to another. These notches must be brought all into one plane, to enable the levers to pass horizontally out of the notches in the plate, in the same way as the two prongs of a fork might traverse one above and the other below the blade of a knife; and when the lever-notches are in this position, all in one plane and in the plane of the plate, the levers can be moved, and with it the stump which shoots the bolt. To ensure this due pressing down of the levers, a key is used such as is shewn in thecut, having six steps or bits to correspond with the six levers; this key, put upon the pinK, presses down all the levers to the exact distance necessary for bringing their notches into one plane, viz. the plane of the plate; the key then being turned round turns the movable platformP, and shoots the bolt. It is evident at a glance, that unless the various steps of the key are so cut, that each shall press down its own lever to the proper extent, the ends of the levers cannot pass the notches in the plate, and the bolt can neither be locked nor unlocked.

It may be well to give Bramah’s own words in relation to this lock: “I may safely assert that it is not in art to produce a key or other instrument by which a lock constructed on this principle can be opened. It will be a task, indeed, of great difficulty, even to a skilful workman, to fit a key to this species of lock, though its interior face were open to his inspection; for the levers being raised by the subjacent springs to an equal height present aplanesurface, and consequentlyconvey no direction that can be of any use in forming a tally to theirregularsurface which they present when acting in subjection to the proper key. Unless, therefore, a method be contrived to bring the notches on the ends of the levers in a direct line with each other, andto retain them in that position till an exact impression of the irregular surface which the levers will then exhibit can be taken, the workman will in vain attempt to fit a key to the lock, or by any effort of art to move the bolt. And when it is considered that this process will be greatly impeded, and may perhaps be entirely frustrated, by the action of the springs, it must appear that great patience and perseverance, as well as great ingenuity, will be required to give any chance of succeeding in the attempt. I do not state this circumstance as a point essential or of any importance to the purpose of the lock, but to prove more clearly what I have before observed upon its principle and properties; for if such difficulties occur to a skilled workman, as to render it almost, if not altogether impracticable to form a key when the lock is open to his inspection and its parts accessible to his hand, it pretty clearly demonstrates the impossibility of accomplishing it when no part of the movement can be touched or seen.”

It is evident that Mr. Bramah had his thoughts directed to that mode of picking locks which depends on taking impressions of the moving parts, rather than to themechanicalorpressuremethod which has been developed in later times. There can be little doubt that a lock was, to his mind, a beautiful and admirable machine, far elevated above the level of mere blacksmith’s work; and his name will ever be associated with what may be termed the philosophy of lock-making.

After the model-lock, which has just been described, was constructed, and found to corroborate the idea which was working in Mr. Bramah’s mind, he proceeded to the construction of his barrel or cylinder-lock, embracing similar elements placed in more convenient juxta-position. In his Essay he gives an engraving to illustrate the principle on which his lockacts, rather in the manner of a diagram than as depicting any lock actually made; his main object being to impart a clear notion of the action of the slides which form such a distinguishing feature in his lock.

fig. 34. Diagram to illustrate the Bramah lock.

Viewed in this sense, therefore, simply as an illustrative diagram, the annexedcutmay represent the action of the safety slides.Bis a sliding bar or bolt, having a power of longitudinal motion in the frameF. This frame has six notches cut on each of its long sides, the two series being exactly opposite each other; and there are six similar notches cut in the boltB. The concurrent effect of all these eighteen notches is, that the six slidesa b c d e fcan move freely up and down across the bolt. When the slides are thus placed, the bolt cannot move, and may in this case be considered to be locked. There are six clefts or notches in the six slides, one to each (1, 2, 3, 4, 5, 6); and until all these are brought in a right line, the bolt cannot move through them. If a tally or key be prepared, as shewn atTin the lower part of the cut, with six projections, and if these projections thrust up the six slides till their clefts rise to the plane of the bolt, then can the bolt be withdrawn or the lock opened. This serves to illustrate the relation between the slides and the key, as carried out in the way now to be described.

One peculiarity of the Bramah lock is, that from theessential part of the apparatus being a barrel or cylinder, much of the working can be conducted in the lathe; and this has given a beauty to the details generally and deservedly admired. Mr. Bramah, when he worked out the theory of his lock, resolved to discard altogether the use of fixed wards, and also the use of tumblers working on a pivot at one end; substituting in their stead a system of slides, working in a very novel way. The body of a Bramah lock may be considered as formed of two concentric brass barrels, the outer one fixed, and the inner rotating within it. The inner barrel has a projecting stud, which, while the barrel is rotating, comes in contact with the bolt in such a way as to shoot or lock it; and thus the stud serves the same purpose as the bit of an ordinary key, rendering the construction of a bit to the Bramah key unnecessary. If the barrel can be made to rotate to the right or left, the bolt can be locked or unlocked; and the problem is, therefore, how to ensure the rotation of the barrel. The key, which has a pipe or hollow shaft, is inserted in the keyhole upon the pin, and is then turned round; but there must be a very nice adjustment of the mechanism of the barrel before this turning round of the key and the barrel can be ensured. The barrel has an external circular groove at right angles to the axis, penetrating to a certain depth; and it has also severalinternallongitudinal grooves, from end to end. In these internal grooves thin pieces of steel are able to slide, in a direction parallel with the axis of the barrel. A thin plate of steel, called the locking-plate, is screwed in two portions to the outer barrel, concentric with the inner barrel; and at the same time occupying the external circular groove of the inner barrel; this plate has notches, fitted in number and size to receive the edges of the slides which work in the internal longitudinal grooves of the barrel. If this were all, the barrel could not revolve, because the slides are catching in the grooves of the locking-plate; but each slide has also a groove, corresponding in depth to the extent of this entanglement; and if this groove be brought to the plane of the locking-plate,the barrel can be turned, so far as respects that individual slide. All the slides must, however, be so adjusted that their grooves shall come to the same plane; but as the notch is cut at different points in the lengths of the several slides, the slides have to be pushed in to different distances in the barrel, in order that this juxta-position of notches may be ensured. This is effected by the key, which has notches or clefts at the end of the pipe equal in number to the slides, and made to fit the ends of the slides when the key is inserted; the key presses each slide, and pushes it so far as the depth of its cleft will permit; and all these depths are such that all the slides are pushed to the exact position where their notches all lie in the same plane; this is the plane of the locking-plate, and the barrel can be then turned.

fig. 35. Exterior of a Bramah lock.

fig. 36. Details of the Bramah lock.

This is the principle which Mr. Bramah adopted; and we have now to trace it, step by step, by means of illustrative details.Fig. 35represents the exterior of a box or desk lock, one among many varieties which the Bramah lock presents.A Ashews the bolt, formed something like two hooks rising out of a bar of metal, which bar has a backward and forward motion upon the plateB B. The upper edge of this plate is turned over at right angles, forming a small horizontal surface through which two openings are cut to receive the two hooked portions of the bolt. The movements of the bolt are otherwise guided by the edges of square holes through which it works;the holes being made in the edge-pieces of the lock, riveted to the main plate. The bolt is further prevented from rising out of its place by means of a plate of metalC, which is secured to the edge-pieces by two screws 1, 1, and by two steadying pieces. This plate has on its surface a cylindrical projectionD, which contains in effect all the working mechanism of the lock. The pins 4 4 are employed for securing a plate, which we shall have to describe presently. When such a lock is fixed upon a desk or box, the portionDprojects to a small distance through a hole in the wood-work, forming in itself a very neat escutcheon, with a key-hole in the centre.

fig. 37. The slides.

So much for the exterior. We must now proceed to examine the interior of the lock, especially the part contained within the cylinder. Infig. 36, for convenience of arrangement, the several parts are exhibited separately, and as if the plane of the lock were horizontal, with the key acting vertically. The essential part of the mechanism is a barrel or cylinderE, pierced or bored with a cylindrical hole down its centre. The inside of the bore has six narrow grooves, cut parallel with the axis, and in the direction of radii; the grooves are not cut through the thickness of the cylinder, but leave sufficient substance of metal for strength. In every groove is fitted a steel slide of peculiar form, such as is shewn ata´ a´infig. 37. Each slide is split in its thickness (seen in section), so that it may move up and down in its groove with a slight friction, andthereby not fall simply by its own weight. Each slide has three small notches (3, 2, 3´), the use of which will presently appear. Reverting tofig. 36, the lower part of the opening through the cylinderEis closed by a circular plate of metal, fixed to it by two screws; this plate is represented atF, in the lower part of the figure. This plate has a vertical pin rising from its centre (also seen atb,fig. 39), and serving as a key-pin on which the pipe of the key may work or slide; and it has also a short circular studcprojecting from its under side, and fitted to enter into a curved opening in the bolt presently to be described.

The point to be now borne in mind is this, that if the cylinderEturns round, the plateFwill also turn round, and with it the studc; and as this stud works into the peculiarly formed cavitydin a portion of the bolt (fig. 38), it causes the bolt to be shot backwards or forwards. Now, in order to prevent this rotating of the cylinder unless the proper key be employed, the following mechanism is introduced: the cylinder has a groove cut round its circumference ate e, extending sufficiently near to the internal bore to produce the desired effect without too much weakening the metal. Into this notch is introduced the thin circular plate of metalf f, it being divided into two halves for this purpose; and when so placed, it occupies the position shewn by the dotted portione e. When this plate is screwed to the case of the lock by the screws 4, 4, it cannot of course turn round; but the cylinder itself will or will notturn round according to the position of the slides. The platef fhas six notches, 5, 5, 5, &c. in the inner edge or circle; so adjusted that, when the plate is in its place, the slidesa acan move up and down. The cylinder cannot move round in a circle without carrying the slides with it; and these cannot so move unless they are all depressed to such exact distances in their respective grooves, that the deep notch of each slider (shewn at 2 infig. 37) shall come into the plane of the circular plate: when all are so brought, the cylinder can be turned. If any one of the slides be pressed down either too low or not low enough, this turning of the cylinder cannot be effected, because the slides will be intersected by the edges of the notches 5, 5; and it is the office of the key, therefore, to press all the six slides down to the exact distances required. When the slides are not pressed upon by the key, they are forced upwards to the top of the cylinder by a spiral spring 6, coiled loosely round the pinb; this pressure forces up a small collet, 7, on which the upper part of the slides rest by a sort of step.

fig. 38. The bolt.

The first locks were made with a separate and independent spring to each slide; but it is a very great improvement, the introduction of one common spring to raise up the whole number; because if a person attempts to pick the lock by depressing the slides separately by means of any small pointed instruments, and by chance brings two or more of them to the proper depth for turning round, should he press any one too low, it is difficult to raise it again without relieving the spring 6, which immediately throws the whole number of slides up to the top, and destroys all that had been done towards picking the lock. Another improvement of this lock, and one which very much increased the difficulty of picking, and its consequent security, was the introduction of false and deceptive notches cut in the sliders, as seen at 3, 3. It was found that in the attempt to pick this lock, an instrument was introduced by the keyhole to force the cylinder round. At the same time that the slides were depressed by separate instruments, those slides which were not at the proper levelfor moving round were held fast by the notches 5, 5 in the platef fbearing against their sides; but when pressed down to the proper level, or till the notch 2 came oppositef f, they were not held fast, but were relieved. This furnished the depredator with the means of ascertaining which slides were pressed low enough, or to the point for unlocking. The notches 3, 3 in the slides are sometimes cut above the true notch 2, sometimes below, and at other times one on each side (one above and one below); they are not of sufficient depth to allow the cylinder to turn round, but are intended to mislead any one who attempts to pick, by his not knowing whether it is the true notch or otherwise, or even whether the slider be higher or lower than the true notch.

We have not yet sufficiently described the key of the Bramah lock. One merit of the lock is the remarkable smallness of the key, which renders it so conveniently portable. The key, as shewn in the upper part of the figure, has six notches or clefts at the end of its pipe or barrel; these clefts are cut to different depths, to accord with the proper extent of movement in the slides. There is a small projection, 10, near the end of the pipe, fitted to enter the notchDin the cylinder; this forces the cylinder round when the parts are all properly adjusted. The bolt of the lock, when properly shot or locked, is prevented from being forced back by the studcon the bottom,F, of the cylinder coming into a direct line with its centre of motion, as shewn infig. 39; in this position no force, applied to drive the bolt back, would have any tendency to turn the cylinder round.

fig. 39. Section of the Bramah cylinder.

To facilitate the comprehension of this very curious and beautiful mechanism, the cylinder is shewn in section in the annexedfig. 39, the same letters and figures of reference being used as before. In the whole of this description we have spoken of six slides, and six only; but Bramah locks may be, and have been, constructed with a much larger number.

There have been several attempts made to modify the action of Bramah’s lock, or to combine this action with that ofsome other inventor. It will suffice to describe one of these. The lock invented by Mr. Kemp of Cork, and for which a patent was obtained in 1816, is called by him theUnionlock, as combining the principles of Barron’s and Bramah’s locks. It contains two, three, or more sliders or tumblers, operated upon by two, three, or more concentric tubes. These concentric tubes are of different lengths, and are placed inside the barrel of the key; so that the barrel may, in fact, be conceived to consist of a series of concentric tubes. These tubes are made of such respective lengths as to push back the tumblers, sliders, or pins which detain the bolt; and this to the precise extent that will bring certain notches in all the sliders to the position which will allow the bolt to pass. The inventor gives this lock its distinctive appellation because it combines something of the pushing motion which Bramah gives to his key, with something of the tumbler-motion observable in Barron’s locks. The principle of safety is considered here to rest chiefly on the extreme difficulty of imitating the key.

Mr. Bramah calculates the number of changes of position which the slides of his lock are capable of assuming before the right one would be attained. “Let us suppose the number of levers, slides, or other movables by which the lock is kept shut, to consist of twelve, all of which must receive a different and distinct change in their position or situation by the application of the key, and each of them likewise capable of receiving more or less than its due, either of which would be sufficientto prevent the intended effect. It remains, therefore, to estimate the number producible, which maybe thus attempted. Let the denomination of these slides be represented by twelve arithmetical progressionals; we find that the ultimate number of changes that may be made in their place or situation is 479,001,600; and by adding one more to that number of slides, they would then be capable of receiving a number of changes equal to 6,227,020,800; and so on progressively, by the addition of others in like manner to infinity. From this it appears that one lock, consisting of thirteen of the above-mentioned sliders, may (by changing their places only, without any difference in motion or size,) be made to require the said immense number of keys, by which the lock could only be opened under all its variations.”

The lock-manufacture in America has undergone some such changes as in England. The insufficiency of wards to the attainment of security has been for many years known; and the unfitness of even tumblers to attain this end, without auxiliary contrivances, has been fully recognised for a dozen years back. In this, and in other mechanical arts, the American machinists depended primarily on the invention of the artisans in the mother country, rather than on those of any continental European state. But the development of the art in the United States has not been wanting in originality; the varieties of locks have been very numerous, and many of them exceedingly ingenious. It is not necessary, however, to describe or depict any of those of simple form. The warded locks of different countries very much resemble each other; the intricate wardedlocks made in France in the last century have long fallen into disuse, in consequence of the general conviction that no arrangement of wards, however intricate, can afford the degree of security required in a good lock. It will be more to the purpose, therefore, to proceed at once to a notice of those American locks which, during the last few years, have acquired some celebrity; first, however, noticing one of older date.

Stansbury’s lock, invented in the United States about forty years ago, may be regarded as a modification of the Egyptian lock. It had a bolt, case, and key-hole somewhat similar to those of modern locks; but there were peculiarities of construction in other respects. There was a revolving plate, pierced with a series of holes, and having a bit or pin which moved the bolt. On the lock-case were a series of springs, each having a pin at one end; and the arrangement was such that, when the bolt was locked or unlocked, each pin would be pressed into some one of the holes. Like as in the Egyptian lock (figs. 1to4), each pin had to be pushed out, and all of them simultaneously, to allow the plate to turn and move the bolt. The key was made with a barrel and bit; and on the front end of the bit was a series of pins corresponding in position with the holes in the plate. The mode of locking or unlocking was as follows: the key was inserted in the key-hole, and turned to a certain position; it was then pressed in with some force, until the pins on the key met those in the plate; when the latter, yielding to the pressure, left the plate free to turn and move the bolt. Modifications of the Egyptian lock, more or less resembling this, have been brought out in some variety on both sides of the Atlantic; but scarcely any have equalled in simplicity the curious wooden relic of by-gone ingenuity in the art of lock-making.

A lock made a few years ago by Mr. Yale, in the United States, somewhat resembles the Bramah lock in having a cylinder or barrel, or rather two concentric cylinders, one working within the other. These cylinders are held together by pins which pass through them both into the key-hole. On the backof the inner cylinder is a pin that fits into a slot in the bolt, and moves it whenever the cylinder is turned. The pins that hold the cylinders together are each cut in two; the pieces of the various pins differing in lengths as irregularly as possible. The key is so peculiarly formed, that, on inserting it in the key-hole, it thrusts the pins radially outwards; each pin being pushed just so far that the joint of the pin shall coincide with the joint between the two cylinders. The inner cylinder can then be turned, by which the bolt is locked or unlocked. If, by the use of a false key, any pin be pushed in too far, it will be as ineffectual in opening the lock as if it were not thrust in far enough; and some of these locks having been made with as many as forty pins, the chances are very numerous against the right combination being hit upon. There is a combination of something like the Egyptian with something like the Bramah lock, here attempted.

One of the principal constructions adopted in America a few years back for bank-locks is that of Dr. Andrews of Perth Amboy, in New Jersey. It was up to that time (1841) believed that the best locks, both of England and America, were proof against any attempts at picking derived from knowledge obtained by inspection through the key-hole; but there still remained the danger that the sight of the true key, or the possession thereof, for only a few minutes, would enable a dishonest person to produce a duplicate. It was to contend against this difficulty that Dr. Andrews directed his attention; and he sought to obtain the desired object by constructing a lock, the interior mechanism of which could be changed at pleasure. The lock of his invention is furnished with a series of tumblers and a detector. The tumblers are susceptible of being arranged in any desired order; and the key has movable bits which can be arranged so as to correspond with the tumblers. When the lock is fixed in its place, no change can be made in the tumblers, and consequently only one arrangement of the bits of the key will suit for the shooting and withdrawing of the bolt. The owner can, however, before the fixing of the bolt, adoptany arrangement of tumblers and bits which he may choose. But though the tumblers cannot be actually re-arranged in any new order within the lock while the latter is fixed, yet by an ingenious contrivance the tumblers can be so acted upon as to render the lock practically different from its former self. The purchaser receives with his lock a series of small steel rings, each ring corresponds in thickness with the thickness of some one of the bits of the key; so that, by suitable adjustment, any one of the bits may be removed from the key, and a ring be substituted in its place. The effect of this substitution is, that the particular tumbler which corresponds with the ring is not raised by it; it is drawn out with the bolt, as if it were part of the bolt itself. Supposing the lock to be locked by this means, the original key would not now unlock it; for one of the tumblers has now been displaced, and can only be re-adjusted by the same ring which displaced it. If an attempt be made to open the lock by the original key, or by the key in its original adjustment, a detector is set in action, which indicates that a false key or other instrument has been put into the lock. One, or more than one, of the bits may be removed from the key, and rings be substituted, and consequently one or more of the tumblers may be disturbed in this peculiar way; so that the lock may change its character in all those permutating varieties which are so observable in most “safety-locks.” The shape of the tumblers is, of course, such as to facilitate this action; they have each an elongated slot, and also two notches; when a tumbler is raised by one of the bits of the key, one of the notches closes around a stump fitted into the case of the lock, and prevents the tumbler from being moved onward with the bolt; but when a ring has been substituted for a bit on the key, the tumbler cannot be raised at all; it is carried onward by a stump on the bolt.

Dr. Andrews is also the inventor of a lock which he terms thesnail-wheel lock. In this lock a series of revolving discs, or wheels, taking the place of the tumblers, are mounted on a central pin, on which the pipe of the key is inserted. Eachdisc has a piece cut out of it, into which the bit of the key enters, and in turning round moves the discs according to the various lengths of the steps on the key. On the outer edge of each disc is a notch, and by the turning of the key all these notches are brought into a line, so that a moveable tongue, ortoggle, attached to the bolt, falls into the notches; the key is then turned the reverse way, by which means the bolt is projected.

About the time when Dr. Andrews invented his first lock, Mr. Newell, of the firm of Day and Newell of New York, constructed a lock which possessed the same distinctive peculiarity as that of Andrews, viz. that the key might be altered any number of times without rendering it necessary to remove the lock or change its internal mechanism. This was brought about, however, in a different manner. Instead of having, as in the Andrews lock, a two-fold movement to every tumbler, Mr. Newell employed two sets of tumblers, the one set to receive motion from the other, and having different offices to fill, to be acted upon by the key in respect to the first series, and to act upon the bolt in respect to the second. Calling these two setsprimaryandsecondary, the action of the lock may be briefly described as follows. A primary tumbler being raised to the proper height by the proper bit in the key, raises the corresponding secondary tumbler; the secondary tumbler is held up in a given position during the locking, while the primary becomes pressed by a spring into its original position. It results from this arrangement that the bolt cannot be unlocked until the primary tumbler has been raised to the same height as before, so as to receive the tongue of the secondary tumbler. And as this is the case in respect to any one primary and its accompanying secondary tumblers, so is it the case whether each set comprises four, five, or any other number. The key may be altered at pleasure, and will in any form equally well shoot the bolt; but the lock can only be unfastened by that arrangement of key which fastened it.

It is, however, desirable to trace the course of improvementsmore in detail, because every successive change illustrates one or other of the several properties required in a good lock. Messrs. Day and Newell’s lock was not finally brought to an efficient form without many attempts more or less abortive. Mr. Newell conceived the idea of applying a second series of tumblers, so placed as to be acted on by the first series. Each of these secondary tumblers had an elongated slot, such that a screw could pass through all of them; the screw having a clamp to overlap the tumblers on the inside of the lock. The head of the screw rested in a small round hole on the back of the lock, so placed as to form a secondary key-hole, to which a small key was fitted. There was thus a double system of locking, effected in the following way: when the large key had been applied, and had begun to act on the primary tumblers, the small key was used to operate on the clamp-screw, and thus bind all of the secondary tumblers together, ensuring their position at the exact heights or distances to which the primary key had caused them to be lifted. The bolt was then free to be shot, and the first series of tumblers reverted to their original position.

But such an arrangement has obvious inconveniences. Few persons would incur the trouble of using two keys; and besides this, there were not wanting certain defects in the action and reaction of the several parts; for if the clamp-screw were to be left unreleased, the first series of tumblers would be upheld by the second series in such a way that the exact impression of the lengths of the several bits of the key could be obtained through the key-hole while the lock was unlocked or the bolt unshot. To remedy one or both of these evils was the next object of Mr. Newell’s attention. He made a series of notches or teeth in each of the secondary tumblers, corresponding in mutual distance with the steps or bits of the key; and opposite these notched edges he placed a dog or lever, with a projecting tooth suitable to fall into the notches when adjusted properly in relation to each other. When the key was used, the primary tumblers were raised in the usualway, and acted on the secondary tumblers; these latter were so thrown that the dog-tooth caught in the notches and held them fast, thereby rendering the same service as the clamp-screw and the small key in the former arrangement. No other relative position of the bits of the key could now unlock the lock.

Still, improvement as it was, this change was not enough; Mr. Newell found that his lock, like all the locks that had preceded it, was capable of being picked by a clever practitioner; and candidly admitting the fact, he sought to obtain some new means of security. He tried what a series of complicated wards would do, in aid of the former mechanism; but the result proved unsatisfactory. His next principle was to provide a number of false notches on the abutting parts of the primary and secondary tumblers, with alterations in other parts of the apparatus. The theory now depended upon was this, that if the bolt were subjected to pressure, the tumblers would be held fast by false notches, and could not be raised by any lock-picking instrument. To increase the security, a steel-curtain was so adjusted as to cover, or at least protect, the key-hole. Great anticipations were entertained of this lock, but they were destined to be negatived. A clever American machinist, Mr. Pettit, accepted Messrs. Day and Newell’s challenge (500 dollars to any one who could pick this lock); he succeeded in picking the lock, and thus won the prize.

Once again disappointed, Mr. Newell re-examined the whole affair, and sought for some new principle of security that had not before occurred to him. He had found that, modify his lock how he might, the sharp-eyed and neat-fingered mechanician could still explore the interior of the lock in such a way as to find out the relative positions of the tumblers, and thus adapt their means to the desired end. How, therefore, to shut out this exploration altogether became the problem; how to make a lock, the works of which should beparautoptic—to coin a word from the Greek, which should signifyconcealed from view. The result of his labours was the production ofthe American bank-lock now known by that name. The details of this lock may now conveniently be given.

fig. 40. The American Parautoptic lock; bolt unshot.

fig. 41. The same with the bolt shot.

Infig. 40the lock is represented in its unlocked state, with the cover or top-plate removed; the auxiliary tumbler and the detector-plate are also removed. Infig. 41it is represented as locked, with the cover and the detector-plate also removed, and the auxiliary tumbler in its place. In these two figures, the same letters of reference apply to the same parts, unless otherwise stated.B Bis the bolt;T1are the first series of movable slides or tumblers;sshews the tumbler-springs;T2the secondary series of tumblers; andT3the third or intermediate series—these latter coming between the first and secondary series;P Pare the separating plates between the several members of the first series of tumblers;s1are the springs for lifting the intermediate tumblers. On each of the secondary tumblersT2is a series of notches, corresponding in mutual distance with the difference in the lengths of the movable bits of the key. It thence happens that, when the key is turned in the lock to lock it, each bit raises its proper tumbler, so that some one of these notches shall present itself in front of the toothtinthe dog or leverL L. When the boltBis projected by the action of the key, it carries with it the secondary tumblersT2, and presses the toothtinto the notches; in so doing, it withdraws the tonguesdfrom between the jawsj jof the intermediate tumblersT3, and allows the first and intermediate tumblers to fall to their original position. By the same movement, the secondary tumblersT2become held in the position given to them by the key, by means of the toothtbeing pressed into the several notches, as shewn in the closed state of the lock (fig. 41). Now let us see what results if any attempt be made to open the lock with any arrangement of key but that by which it has been locked. In such case, the tonguesdwill abut against the jawsj j, preventing the bolt from being withdrawn; and should an attempt be made to ascertain which tumbler binds and requires to be moved, the intermediate tumblerT3(which receives the pressure), being behind the iron wallI I, which is fixed completely across the lock, prevents the possibility of its being reached through the key-hole; and the first tumblersTare quite detached at the time, thereby makingit impossible to ascertain the position of the parts in the inner chamber behind the wallI I.Kis the drill-pin, on which the key fits; andCis a revolving ring or curtain, which turns round with the key, and prevents the possibility of inspecting the interior of the lock through the key-hole. Should, however, this ring be turned to bring the opening upwards, a detector-plateD,fig. 42, is immediately carried over the key-hole by the motion of a pinp1upon the auxiliary tumblerT4, which is lifted by the revolution of the ringC, thereby effectually closing the key-hole. As an additional protection, the bolt is held from being unlocked by the stud or stumpSbearing against the detector-plate; and, moreover, the leverl lholds the bolt, when locked, until it is released by the tail of the detector-plate pressing the pinp1;l1is a lever which holds the bolt on the upper side, when locked, until it is lifted by the tumblers acting on the pinp1;Xare separating-plates between the intermediate tumblersT3;u u1are the studs for preserving the parallel motion of the different tumblers.

fig. 42. The detector plate of the Parautoptic lock.

Fig. 43represents the key in two different forms, or with the bits differently arranged. Either form will lock the lock, but the other will not then unlock it. The end of the key is represented infig. 44, shewing the screw which fixes the bitsin their places. The bits for a six-bitted key are shewn separately infig. 45.

fig. 43. Key of the Parautoptic lock.

fig. 44. End view of the key.

fig. 45. Separate bits of the key.

In 1847 the parautoptic lock was exhibited at Vienna before the National Mechanics’ Institute of Lower Austria; and towards the close of the year Mr. Belmont, consul-general of Austria at New York, placed in the hands of Messrs. Day and Newell a letter, a diploma, and a gold medal, forwarded by the Institute. The letter was from the president of the Institute to Mr. Newell, and was couched in the following terms:

“The Institute of Lower Austria, at its last monthly session, has passed the unanimous resolution to award to you its gold medal, as an acknowledgment of the uncommon superiority of the combination-lock of your invention; and this resolution was ratified in its general convention held on the 10th instant.

“Whilst I, as president of this Institute, rejoice in seeing the services which by this invention you have rendered to the locksmith’s art thus appreciated and recognised, I transmit to you, enclosed, the said medal, together with the documents relatingto it; at the same time availing myself of this opportunity to assure you of my esteem.

“Colloredo Mannsfeld.

“Vienna, May 31st, 1847.”

The diploma and the medal were similar to other honorary distinctions of the same class, and need not be described here; but the report of the special committee may be given, as it expresses the opinions of the Viennese machinists on the relative principles by which safety is sought to be obtained in different kinds of locks.

REPORT

Of a Special Committee on the new Parautoptic Permutation Lock of the American Newell, made known to the Lower Austrian Institute by the Councillor, Professor Reuter, and on the motions relating to it made by the same and accepted by the Institute. Presented at the monthly meeting, April 6th, 1847, by Mr. Paul Sprenger, Aulic Councillor on Public Works, &c. &c.Gentlemen:—At our last monthly meeting, Mr. Reuter, Aulic Councillor and Secretary of the Institute, directed your attention to a newly invented lock of Mr. Newell, of North America, which was represented as excelling all other changeable combination-locks hitherto known, and as being without a rival.The Special Committee which was intrusted with the examination of this lock, and of the motions made by the said Secretary, and accepted by the Institute, has conferred on me the honour of making you acquainted with the results of its investigations.The attention of your committee was chiefly occupied with the three questions proposed by the said Aulic Councillor in relation to the lock in question:First: Whether the idea of Mr. Newell was of any practical value for already existing and still-to-be-invented combination-locks;Secondly: Whether the idea was of sufficient importance to be published and minutely described in the transactions of the said Institute; andThirdly: Whether the merits of the inventor were of sufficient importance to entitle him to a distinction from the said Institute.The deliberations on the first question, viz. the newness of the idea, and of its practical value, would of necessity enlist the particular attention of your committee, especially since by far the greater number of its members are by their avocation called upon to be interested in the execution of all kinds of locks.It is therefore the unanimous opinion of your committee, that the ideaof the American Parautoptic Combination-Lock is entirely new and without example.The combination-locks with keys have, with few exceptions, such an arrangement that a determinate number of movable parts (the so-called combination-parts) must by the turning of the key be raised or lifted into a certain position, if it is desired to project the bolt, or, what is the same thing, to lock it out; consequently these parts, or, as they are technically termed, tumblers, could not be transposed or changed, from the circumstance that the key-bit was one solid piece, with various steps or notches adapted to the several tumblers, and one impression from it destroyed the security of the lock.In order, however, to add more security to such a combination-lock, and to make the key, in case it should be lost, or any counterfeit made from a wax impression, useless for an unlawful opening of the lock, another step was taken: the key-bit was made to consist of several bits or movable parts, in such a manner that the owner of the lock was enabled to change the bits, and to form,as it were, new keys different from the former. But since the bolt of the lock can only be projected whilst the combination parts or tumblers are in a certain position, which position depends upon the order of the bits in the key, it is evident that the owner, when changing the key, must at the same time make a corresponding change in the position of the tumblers in the lock itself, before the lock can be of any use for the newly changed shape of the key, which rendered it troublesome, and impracticable for the purpose designed, from the fact that no positive change could be made in the lock, without taking it from the door, and then taking the tumblers out of the case, to change them in a suitable form for the key.This principle of changing the lock is rarely adhered to, as few men understand the machinery of a lock sufficiently to undertake the task; and this circumstance rendered the lock quite as insecure as the former one described.Another step toward the perfection of combination-locks consisted in this, that the key remains unaltered whilst the combination parts of the lock can, before it is locked, be brought into different positions by means of movable plates on the frame of the lock. These plates were arranged by hand to certain figures, and depended on the memory for adjustment at each time the bolt was to be locked out or in, the key operating only on the bolt, to move it back and forth when the plates were set in proper positions for the purpose; and should the owner forget the arrangement of the plates, after projecting the bolt, his key is of no use to him, and he must resort to the skill of the locksmith to gain access.The same case may occur in the far less perfect ring-lock of Reynier, which is operated without keys, and is opened by means of the rings being turned in a particular position; on these rings are usually stamped letters, which, by introducing some word readily suggested to the memory, thus point out the relative position of the rings.But although in case of these ring-locks the owner is enabled to producea change in the rings in such a manner that the opening of the lock can, as it were, only become possible by rightly arranging the altered position of the letters, still this lock of Reynier’s does not possess that safety and perfection which could have insured it universal application.M. Crivelli, formerly professor at Milan, has given a minute description of the imperfection of ring-locks generally, in the annals of the Imperial Royal Polytechnic Institute.It is the unanimous conviction of your committee that the American Lock of Newell surpasses, in the ingenuity displayed in its construction, all other locks heretofore known, and more especially in this, that the owner can, with the greatest facility, change at pleasure the interior arrangement of his lock to a new and more complex one, at every moment of his life, simply by altering the arrangement of the bits in the key, and this is accomplished without removing the lock or any part of it from its position on the door.Its operation is as follows:—At the closing or locking of the lock, whilst the bolt is projecting, the movable combination parts assume precisely the position prescribed to them by the key, according to the particular arrangement of its bits at the time the key is turned.The combination parts do not consist in one set of tumblers only, such as are found in all other locks, but there are three distinct sets or component parts fitting into each other. When the bolt is projected, it dissolves the mutual connexion of the constituent pieces, and carries along with it such as are designedly attached to it, and which assume the particular positions given them by the key in its revolution. These parts are rendered permanent in their given form by means of a lever adapted for the purpose, while the parts not united with the bolt are pressed down by their springs to their original places.If now the bolt is to be returned again,i. e.if the lock is to be unlocked, then the constituent pieces or tumblers which are in the original state must, by means of the key, be again raised into that position in which they were when the lock was closed, as otherwise the constituent parts attached to the bolt would not lock in with the former, and the bolt could not be returned. Nothing, therefore, but the precise key which had locked the lock can effect the object.This idea in itself, considered by your committee, is as ingenious as it is new, and is accompanied by a perfection in its execution which reflects the highest honour on Mr. Newell, the inventor and manufacturer of the lock.The lock is built strong and solid, and the several parts are admirably adapted to the functions which they are designed to perform. The walls of steel or iron which separate the security parts from the tumblers, and the cylinder which revolves with the key, present formidable barriers to all descriptions of pick-locks, and render the lock a most positive and reliable security. The tumblers consist of rolled very smooth steel plates, in which the fire-crust has not been filed away, partly in order that the lock might not need oiling, as all these parts are very smooth, and partly that thecombination pieces might not easily rust, a thing to which the adhering fire-crust is not favourable. The springs, which by the turning of the key must be raised together with the tumblers, are attached to levers, and press upon the latter at their centre of gravity, in consequence of which all crowding towards either side is prevented, and the key can be turned with facility, in spite of the many combination parts which it has to raise; and the springs themselves are by their positions so little called into action, that their strength can never be impaired by use.The lock has also another very complete arrangement in the detector-tumbler, which is attached to the cap or covering of the lock. This tumbler, on turning the key either way, closes the key-hole, and not only prevents the use of false instruments in the lock, but detects all attempts at mutilating its interior parts.This lock is especially useful for locking bank-vaults, magazines, counting-houses, and iron-safes, in which valuable effects, money, or goods are to be deposited for safe keeping. When it is considered that the bits of the key belonging to this lock can be transferred into every possible form within its limits, and since the construction of the lock admits of every combination of the slides resulting from the changes of the key, therefore the lock in question is, in every respect, deserving of the appellation given to it by the Secretary of the Institute, namely, the Universal Combination Lock; and justly so, when we consider that the ten bits attached to the key admit of three millions of permutations, and upward; consequently forming that number of different kinds of keys and locks.If we consider further, that we need not be limited to the given bit, but that others can be applied, differing in their dimensions from the former; and again, if we consider that from every system arising from a difference in their relative dimensions, a large number of new keys differing from each other will result, and that this can be effected in a space scarcely occupying a square inch,—then we cannot refrain from confessing that the human mind, within this small space, has shewn itself to be infinitely great.After this preliminary and general exposition, your committee can answer the three questions propounded to them the more briefly, as the locks heretofore known have all been noticed.To question first.—On the practical value of the invention of Mr. Newell, your committee were unanimous and positive that the principle on which it is based should be preserved.To question second.—For this reason the committee deemed it desirable that a drawing and description of the American lock in question should be published in the Transactions of the Institute of Lower Austria.To question third.—With regard to the claims of the inventor, Mr. Newell, to an honorary distinction from the Institute of Lower Austria, the committee recommend that he be presented with a Diploma of honourable mention and a Gold Medal.The members of your committee, consisting mostly of fellow-tradesmen of Mr. Newell, experience great satisfaction in the fact that it has fallen totheir lot to vote to their colleague on the other side of the ocean an acknowledgment of his successful ingenuity, and they close the Report with the request that the Institute will transmit to Mr. Newell of New York, in North America, the Diploma and Gold Medal, together with a copy of this Report, according to the motion of the Aulic Councillor and Professor Reuter.[An exact copy of the original Report as preserved in the archives of the National Mechanics’ Institute of Lower Austria.]DR. SCHWARTZ,Assistant Secretary of the Institute.

Gentlemen:—At our last monthly meeting, Mr. Reuter, Aulic Councillor and Secretary of the Institute, directed your attention to a newly invented lock of Mr. Newell, of North America, which was represented as excelling all other changeable combination-locks hitherto known, and as being without a rival.

The Special Committee which was intrusted with the examination of this lock, and of the motions made by the said Secretary, and accepted by the Institute, has conferred on me the honour of making you acquainted with the results of its investigations.

The attention of your committee was chiefly occupied with the three questions proposed by the said Aulic Councillor in relation to the lock in question:

First: Whether the idea of Mr. Newell was of any practical value for already existing and still-to-be-invented combination-locks;

Secondly: Whether the idea was of sufficient importance to be published and minutely described in the transactions of the said Institute; and

Thirdly: Whether the merits of the inventor were of sufficient importance to entitle him to a distinction from the said Institute.

The deliberations on the first question, viz. the newness of the idea, and of its practical value, would of necessity enlist the particular attention of your committee, especially since by far the greater number of its members are by their avocation called upon to be interested in the execution of all kinds of locks.

It is therefore the unanimous opinion of your committee, that the ideaof the American Parautoptic Combination-Lock is entirely new and without example.

The combination-locks with keys have, with few exceptions, such an arrangement that a determinate number of movable parts (the so-called combination-parts) must by the turning of the key be raised or lifted into a certain position, if it is desired to project the bolt, or, what is the same thing, to lock it out; consequently these parts, or, as they are technically termed, tumblers, could not be transposed or changed, from the circumstance that the key-bit was one solid piece, with various steps or notches adapted to the several tumblers, and one impression from it destroyed the security of the lock.

In order, however, to add more security to such a combination-lock, and to make the key, in case it should be lost, or any counterfeit made from a wax impression, useless for an unlawful opening of the lock, another step was taken: the key-bit was made to consist of several bits or movable parts, in such a manner that the owner of the lock was enabled to change the bits, and to form,as it were, new keys different from the former. But since the bolt of the lock can only be projected whilst the combination parts or tumblers are in a certain position, which position depends upon the order of the bits in the key, it is evident that the owner, when changing the key, must at the same time make a corresponding change in the position of the tumblers in the lock itself, before the lock can be of any use for the newly changed shape of the key, which rendered it troublesome, and impracticable for the purpose designed, from the fact that no positive change could be made in the lock, without taking it from the door, and then taking the tumblers out of the case, to change them in a suitable form for the key.

This principle of changing the lock is rarely adhered to, as few men understand the machinery of a lock sufficiently to undertake the task; and this circumstance rendered the lock quite as insecure as the former one described.

Another step toward the perfection of combination-locks consisted in this, that the key remains unaltered whilst the combination parts of the lock can, before it is locked, be brought into different positions by means of movable plates on the frame of the lock. These plates were arranged by hand to certain figures, and depended on the memory for adjustment at each time the bolt was to be locked out or in, the key operating only on the bolt, to move it back and forth when the plates were set in proper positions for the purpose; and should the owner forget the arrangement of the plates, after projecting the bolt, his key is of no use to him, and he must resort to the skill of the locksmith to gain access.

The same case may occur in the far less perfect ring-lock of Reynier, which is operated without keys, and is opened by means of the rings being turned in a particular position; on these rings are usually stamped letters, which, by introducing some word readily suggested to the memory, thus point out the relative position of the rings.

But although in case of these ring-locks the owner is enabled to producea change in the rings in such a manner that the opening of the lock can, as it were, only become possible by rightly arranging the altered position of the letters, still this lock of Reynier’s does not possess that safety and perfection which could have insured it universal application.

M. Crivelli, formerly professor at Milan, has given a minute description of the imperfection of ring-locks generally, in the annals of the Imperial Royal Polytechnic Institute.

It is the unanimous conviction of your committee that the American Lock of Newell surpasses, in the ingenuity displayed in its construction, all other locks heretofore known, and more especially in this, that the owner can, with the greatest facility, change at pleasure the interior arrangement of his lock to a new and more complex one, at every moment of his life, simply by altering the arrangement of the bits in the key, and this is accomplished without removing the lock or any part of it from its position on the door.

Its operation is as follows:—At the closing or locking of the lock, whilst the bolt is projecting, the movable combination parts assume precisely the position prescribed to them by the key, according to the particular arrangement of its bits at the time the key is turned.

The combination parts do not consist in one set of tumblers only, such as are found in all other locks, but there are three distinct sets or component parts fitting into each other. When the bolt is projected, it dissolves the mutual connexion of the constituent pieces, and carries along with it such as are designedly attached to it, and which assume the particular positions given them by the key in its revolution. These parts are rendered permanent in their given form by means of a lever adapted for the purpose, while the parts not united with the bolt are pressed down by their springs to their original places.

If now the bolt is to be returned again,i. e.if the lock is to be unlocked, then the constituent pieces or tumblers which are in the original state must, by means of the key, be again raised into that position in which they were when the lock was closed, as otherwise the constituent parts attached to the bolt would not lock in with the former, and the bolt could not be returned. Nothing, therefore, but the precise key which had locked the lock can effect the object.

This idea in itself, considered by your committee, is as ingenious as it is new, and is accompanied by a perfection in its execution which reflects the highest honour on Mr. Newell, the inventor and manufacturer of the lock.

The lock is built strong and solid, and the several parts are admirably adapted to the functions which they are designed to perform. The walls of steel or iron which separate the security parts from the tumblers, and the cylinder which revolves with the key, present formidable barriers to all descriptions of pick-locks, and render the lock a most positive and reliable security. The tumblers consist of rolled very smooth steel plates, in which the fire-crust has not been filed away, partly in order that the lock might not need oiling, as all these parts are very smooth, and partly that thecombination pieces might not easily rust, a thing to which the adhering fire-crust is not favourable. The springs, which by the turning of the key must be raised together with the tumblers, are attached to levers, and press upon the latter at their centre of gravity, in consequence of which all crowding towards either side is prevented, and the key can be turned with facility, in spite of the many combination parts which it has to raise; and the springs themselves are by their positions so little called into action, that their strength can never be impaired by use.

The lock has also another very complete arrangement in the detector-tumbler, which is attached to the cap or covering of the lock. This tumbler, on turning the key either way, closes the key-hole, and not only prevents the use of false instruments in the lock, but detects all attempts at mutilating its interior parts.

This lock is especially useful for locking bank-vaults, magazines, counting-houses, and iron-safes, in which valuable effects, money, or goods are to be deposited for safe keeping. When it is considered that the bits of the key belonging to this lock can be transferred into every possible form within its limits, and since the construction of the lock admits of every combination of the slides resulting from the changes of the key, therefore the lock in question is, in every respect, deserving of the appellation given to it by the Secretary of the Institute, namely, the Universal Combination Lock; and justly so, when we consider that the ten bits attached to the key admit of three millions of permutations, and upward; consequently forming that number of different kinds of keys and locks.

If we consider further, that we need not be limited to the given bit, but that others can be applied, differing in their dimensions from the former; and again, if we consider that from every system arising from a difference in their relative dimensions, a large number of new keys differing from each other will result, and that this can be effected in a space scarcely occupying a square inch,—then we cannot refrain from confessing that the human mind, within this small space, has shewn itself to be infinitely great.

After this preliminary and general exposition, your committee can answer the three questions propounded to them the more briefly, as the locks heretofore known have all been noticed.

To question first.—On the practical value of the invention of Mr. Newell, your committee were unanimous and positive that the principle on which it is based should be preserved.

To question second.—For this reason the committee deemed it desirable that a drawing and description of the American lock in question should be published in the Transactions of the Institute of Lower Austria.

To question third.—With regard to the claims of the inventor, Mr. Newell, to an honorary distinction from the Institute of Lower Austria, the committee recommend that he be presented with a Diploma of honourable mention and a Gold Medal.

The members of your committee, consisting mostly of fellow-tradesmen of Mr. Newell, experience great satisfaction in the fact that it has fallen totheir lot to vote to their colleague on the other side of the ocean an acknowledgment of his successful ingenuity, and they close the Report with the request that the Institute will transmit to Mr. Newell of New York, in North America, the Diploma and Gold Medal, together with a copy of this Report, according to the motion of the Aulic Councillor and Professor Reuter.

[An exact copy of the original Report as preserved in the archives of the National Mechanics’ Institute of Lower Austria.]

DR. SCHWARTZ,Assistant Secretary of the Institute.

There are other circumstances connected with the American bank-lock, in relation to events both in the United States and in England, to which attention will be directed in a subsequent chapter.

The English patent for Messrs. Day and Newell’s lock, dated April 15, 1851, runs as follows: “The object of the present improvements is the constructing of locks in such manner that the interior arrangements, or the combination of the internal movable parts, may be changed at pleasure according to the form given to, or change made in, the key, without the necessity of arranging the movable parts of the lock by hand, or removing the lock or any part thereof from the door. In locks constructed on this plan the key may be altered at pleasure; and the act of locking, or throwing out the bolt of the lock, produces the particular arrangement of the internal parts which corresponds to that of the key for the time being. While the same is locked, this form is retained until the lock is unlocked or the bolt withdrawn, upon which the internal movable parts return to their original position with reference to each other; but these parts cannot be made to assume or be brought back to their original position, except by a key of the precise form and dimensions as the key by which they were made to assume such arrangement in the act of locking. The key is changeable at pleasure, and the lock receives a special form in the act of locking according to the key employed, and retains that form until in the act of unlocking by the same key it resumes its original or unlocked state. The lock isagain changeable at pleasure, simply by altering the arrangement of the movable bits of the key; and the key may be changed to any one of the forms within the number of permutations of which the parts are susceptible.”

The “claims” put forth under this patent are the following:—

“1. The constructing, by means of a first and secondary series of slides or tumblers, of a changeable lock, in which the particular form or arrangement of parts of the lock, imparted by the key to the first and secondary series of slides or tumblers, is retained by a cramp-plate.

“2. The constructing, by means of a first and secondary series of slides or tumblers, of a changeable lock, in which the peculiar form or arrangement of parts of the lock, imparted by the key, is retained by means of a tooth or teeth, and notches on the secondary series of slides or tumblers.

“3. The application to locks of a third or intermediate series of slides or tumblers.

“4. The application of a dog with a pin over-lapping the slide or tumblers, for the purpose of holding-in the bolt when the lock is locked or unlocked.

“5. The application of a dog operated on by the cap or detector-tumbler for holding the bolt.

“6. The application of a dog for the purpose of holding the internal slide or tumbler.

“7. The application to locks of curtains or rings, turning and working eccentrically to the motion of the key, for preventing access to the internal parts of the lock.

“8. The application to locks of a safety-plug or yielding-plate, at the back of the chamber formed by such eccentric revolving curtain or ring.

“9. The application to locks of a strong metallic wall or plate, for the purpose of separating the safety and other parts of the lock from each other, and preventing access to such parts by means of the key-hole.

“10. The application to locks of a cap or detective tumbler,for the purpose of closing the key-hole as the key is turned.

“11. The constructing a key by a combination of bits or movable pieces, with tongues fitted into a groove and held by a screw.

“12. The constructing a key having a groove in its shank to receive the detector tumbler.”

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