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CHAP. PAGE

ON THE CONSTRUCTION OF LOCKS.

ON LOCKS AND LOCK-LITERATURE.

The manufacture of locks, and a consideration of the mechanical principles involved in their construction and security, have never yet been treated with any degree of fulness in an English work. Lock-making has occupied a large amount of ingenuity, and lock-patents have been obtained in considerable number, though not always, we are satisfied, with a commensurate return for the expense incurred,--but lock-philosophy has not been largely attended to.

And yet it may safely be said that much which is both mechanically and commercially important is comprised in a lock. Every improvement in the manufacture of iron, steel, and brass--that is, in the tool-making and machine-making processes--may be made to reflect its light on the lock-manufacture; the stamping, the casting, the planing, the slotting, the screw-cutting, the polishing of metals,--all, in proportion as they are improved, impart some of their aid to the lock-maker. Then, in the finer kinds of locks, the works are so delicate as to approach to the nicety of clockwork; thereby combining the manipulative skill of a talented artisan with the rougher mechanical work of the smith. The principles of mechanical science are also appreciated by many lock-makers. The lever, the inclined plane, the eccentric, the cam, the screw, the wheel and pinion, the ratchet, the spring,--all are brought to bear on the internal mechanism of locks, frequently in many novel combinations.

It is worthy of remark, that the tools described are the same as those which are used by the locksmith at the present day; shewing how little improvement has been made in the means of producing locks.

That chapter of the work which has reference to locks is the only one with which we have to do here. It is arranged in a systematic manner, beginning with the simpler locks, without wards or tumblers, and proceeding thence to others of more complex construction. The period at which the work was written was too early to lead us to expect to find a tumbler-lock described and delineated: there are, however, numerous examples of single tumbler-locks, many of them of great ingenuity. The use of multiple bolts, that is, of many bolts shot at once by one action of the key, seems to have been familiar enough to the locksmiths of those days. One lock represented is remarkable; it is attached to a strong and ponderous coffer or chest. The chest is open; and the whole under or inner surface of the cover is seen to be occupied by a lock of intricate construction; there are no less than twelve bolts, three on each long side, one on each short side, and one in each corner; these bolts are so placed as to catch under a projecting rim fixed round the top of the coffer. The collection of keys, exhibited on a separate plate, is remarkable for the great variety of forms given to them. We shall by and by copy some of the drawings of this curious work.

ANCIENT LOCKS: GRECIAN, ROMAN, EGYPTIAN.

Locks and door-fastenings have not, until modern times, been susceptible of any classified arrangement according to their principles of construction. They have been too simple to require it, and too little varied to permit it. That some such fastenings must be employed wherever doors of any kind are used is sufficiently apparent; and there is a little information obtainable, which shews the nature of the fastenings adopted in early times. The bolt, the hasp, the chain, the bar, the latch, the lock, all were known, in one or other of their various forms, in those ages which we are accustomed to consider classical. Travellers, generally speaking, do not descend to locks, or rather they do not think about them; otherwise they might have collected much that would have been novel and applicable to the present work; and, indeed, there is some ground for the assertion, that a notice of the door-fastenings of all nations would reveal to us something of the social and domestic habits of various members of the great human family. Be this as it may, however, we may profitably make a little inquiry into the locks of ancient times.

An examination of the Roman keys in the British Museum sufficiently attests this fact.

"Whilst to his couch himself the prince addressed, The duteous nurse received the purple vest: The purple vest with decent care disposed, The silver ring she pulled, the door reclosed; The bolt, obedient to the silken cord, To the strong staple's inmost depth restored, Secured the valves."

Most of the other great nations of antiquity resembled either the Egyptians or the Greeks and Romans, more or less closely, in their domestic and domiciliary arrangements; or, at any rate, so far as such humble matters as locks and keys are concerned, we need not seek far from those nations for examples. The Nineveh and other Assyrian explorations have, however, revealed many curious and unexpected facts; from the temples and the palaces we may by and by penetrate into the houses and rooms of the citizens sufficiently to know how their doors were fastened. In the mean time ancient Egypt awaits our notice.

In many of the ancient Egyptian doors there were wooden locks fixed so as to fasten across the centre at the junction where the two folds of the door met. It is difficult, by mere inspection of the bas-reliefs and paintings, to decide whether these locks were opened by a key, or were merely drawn backwards and forwards like a bolt; but if they were really locks, it is probable that they were on the same principle as the Egyptian lock still in use. For greater security, these modern locks are occasionally sealed with a mass of clay; and there is satisfactory evidence that the same custom was frequently observed among the ancient inhabitants of that country. Sir J. G. Wilkinson gives a representation of an iron key, now in his possession, which he procured among the tombs at Thebes, and which looks very much like a modern burglar's picklock. In relation to keys generally, and after mentioning the use of bronze for their manufacture, he says: "At a later period, when iron came into general use, keys were made of that metal, and consisted of a straight shank about five inches in length, and a bar at right angles with it, on which were three or more projecting teeth. The ring at the upper extremity was intended for the same purpose as that of our modern keys; but we are ignorant of the exact time when they were brought into use; and the first invention of locks distinct from both is equally uncertain; nor do I know of any positive mention of a key, which, like our own, could be taken out of the lock, previous to the year 1336 before our era; and this is stated to have been used to fasten the door of the summer parlour of Eglon, the king of Moab. The description here adverted to is that contained in Judges iii. 23-25: 'Ehud went forth through the porch, and shut the doors of the parlour upon him, and locked them ... his servants ... took a key, and opened them.'"

This primitive lock comprises many of the best features of the tumbler or lever-locks of later days, as will be seen in a future chapter. There will also be opportunities of shewing how the pin-action has been applied in other ways in some of the modern locks.

LOCK CLASSIFICATION. THE PUZZLE-LOCK AND THE DIAL-LOCK.

In approaching the subject of modern locks it becomes necessary to decide upon some method of treating the widely-scattered and diverse materials which are presented to our notice. One plan would be to trace the subject chronologically, by describing, in the order of their invention, the most important locks which have been presented to public notice. But this would be attended with some disadvantages: the peculiar characters of the several locks would not be brought out with sufficient distinctness; and the result, so far as the reader is concerned, would rather tend to confusion than to a clear appreciation of the subject. There are more advantages belonging to a classification of locks under certain headings, according to some marked peculiarities in their modes of action. This is a convenient plan, but it is not an easy one to put in execution; for inventors have not sought to place their locks in any particular class, but rather to call attention to their merits. Moreover, many locks embody two or three distinct principles so equally, that it will often be difficult to decide in which class to place them. This, nevertheless, may be done with an approach to correctness. It is necessary first, however, to explain certain technical terms by which locks are distinguished one from another.

The above terms are employed chiefly between the makers of the locks and the persons who fix them in their places; but there are other terms and names, more familiarly known, which will come under notice in future pages.

The puzzle or letter-lock of the ring kind, then, consists essentially of a spindle; a barrel, encompassing the spindle; two end-pieces, to keep the spindle and barrel in their places; and the shackle, hinged to one of these end-pieces. To unfasten the lock, one of the end-pieces must be drawn out a little, to allow the shackle or horse-shoe to be turned on its hinge; and the question arises, therefore, how this end-piece is to be acted upon. This is effected in a very ingenious way: there are four studs or projections in a row on the spindle, and as the spindle fits pretty closely in the barrel, the former cannot be drawn out of the latter unless there be a groove in the interior of the barrel, as a counterpart to the studs on the exterior of the spindle; four rings fit on the barrel, on the interior of each of which there is a groove; and unless all these four grooves coincide in direction, and even lie in the same plane as the groove in the barrel, the studs will not be able to pass, and the spindle cannot be drawn out. Each ring may be easily made to work round the barrel by means of the fingers, and to maintain any position which may be given to it. There are outer rings, one over each of the rings just described, with the letters of the alphabet inscribed on each; and these outer rings, by means of notches on the inside, govern the movements of the inner rings.

The action is, therefore, as follows: when the padlock is to be locked, the rings are so adjusted that all the grooves shall be in a right line; the spindle is thrust in, the end-piece is fixed on, and the shackle is shut down. The padlock is now fastened; but a reverse order of proceeding would as easily open it again, and therefore the "safety" or "puzzle" principle is brought into requisition. The outer rings are moved with the finger, so as to throw the various interior grooves out of a right line, and thus prevent the withdrawal of the spindle. As each ring may be turned round through a large or a small arc, and all turned in different degrees, the variations of relative position may be almost infinite. The letters on the outer rings are to assist the owner to remember the particular combination which he had adopted in the act of locking; for no other combination than this will suffice to open the lock. There may, for instance, be the four letters L O C K in a line, which line is brought to coincide with two notches or marks at the ends of the apparatus; and until all the four outer rings are again brought into such relative position as to place the letters in a line, the lock cannot be opened.

"A cap-case for your linen and your plate, With a strange lock that opens with A?M?E?N."

And in some verses by Carew, written about the same time, there is an analogy drawn, in which one of the things compared is--

"A lock That goes with letters; for till every one be known, The lock's as fast as if you had found none."

This curious extract, which was brought forward by Mr. Chubb, in a paper on locks and keys , seems to take away the credit from one with whose name the letter-lock has been most intimately associated. We shall presently explain, however, what it was that Regnier effected towards perfecting the letter-lock. In the meantime it may be interesting to note that the British Museum contains a copy of the work mentioned by Vanhagen. At the page indicated there is an engraving containing a drawing of a veritable puzzle or letter-lock; the lock consists of a cylinder or barrel, on which seven rings work; each of these rings is inscribed with letters, and the ends of the cylinder are grasped by a kind of shackle.

It was a natural result of the arrangement of the letter-lock, as invented by Cardan, that only one particular word or cipher or key could be used in each lock; and it was to increase the puzzle-power of the lock that Regnier doubled all the rings, making each pair concentric, and enabling the user to vary the cipher at pleasure.

These dial-locks have not been numerous; they require wheel and pinion work within the body of the lock, which gives delicacy and complication to the mechanism. The letter padlock, be its merits great or small, is strong and durable, not liable to get out of order; and in so far as it requires no key or key-hole, it occupies rather a special position among locks. One of our great "merchant-princes" has been a letter-lock inventor, as the following will shew.

Early in 1852, Mr. William Brown, the distinguished member for South Lancashire, read a paper before the Architectural and Archaeological Society of Liverpool, of much interest in relation to our present subject. His object was to describe a letter-lock which he had invented, and which had up to that time given high satisfaction. We cannot do better than transcribe the paper, as reported in one of the Liverpool Journals, with a few abridgments.

"As your society are desirous of seeing any improvements or attempts at them, I send you a stock-lock for inspection. The idea for its construction I took from a letter-padlock. I had a lock of this description made by Mr. Pooley twenty-five years ago, which has been in use ever since on Brown, Shipley, and Co.'s safe....

"Its advantages I conceive to be--First, it cannot be picked, for there is no key-hole. Second, it cannot be blown up by gunpowder, for the same reason. Third, you cannot drill through the door so as to reach the lock, for you are intercepted by a steel plate on which your tools will not act: thus you cannot introduce gunpowder that way to force the lock off. Fourth, you cannot bounce off the wheels in the interior with a muffled hammer, for vulcanised India-rubber springs resist this. Fifth, you cannot drill the spindles out, as their heads are case-hardened. Sixth, you cannot drive them in, for they are countersunk in the door about half-way through....

"Now let us set the lock to the word W O O D . When you set the lock, make a private record of them, so that you may not forget them. If parties do not know your letters, nothing but violence, applied by some means or other, can enable them to get into your safe; for the lock will not open to any thing but its talisman. Take off all the large wheels and open the lock: you will see that the large wheels have a number of false chambers; if you get the spurs of the bolt into three real chambers and one false, you are as fast as ever, for all four must be right.

"Having placed your key and pointer outside the door to point to W on brass-plate No. 1, the small wheel inside obeys the same impulse; then maintain your small wheel steadily on this point, and the large wheel No. 1 will only fit on at the right place, the true opening compartment being opposite the spur of the bolt. It being necessary at the time you set your lock that it should be open, proceed with Nos. 2 and 3 in the same way, your pointer standing steadily at O. No. 4 is the same, the pointer being held steadily at D. You should then shoot your lock two or three times, to be sure you have made no mistake. Every time you shoot your bolts out, turn your wheels away from the true chamber, and see when you again turn your pointers to W O O D that your lock opens freely; it is the proof that you have made no mistake, and you may now venture to lock your safe. When you unlock the door, and find it necessary to leave it open for a time, you should shoot the bolts as if locked, and turn the wheels, so that no one may find what your real letters are; and again adjust them to their proper places, in order that the bolt may go back and enable you to re-lock. Once having locked the door and turned the wheels from your real letters, you need not trouble yourself with carrying the key, but leave it in any place beside the lock.

"If this lock is of any value, it should be known; if it has weak points, let them be pointed out, and they may admit of a remedy; for we ought not to be led to believe a lock is safe which is not so."

WARDED LOCKS, WITH THEIR VARIED APPENDAGES.

It must be obvious at a glance, that this back-spring lock is objectionable on the score of security, on account of the facility with which the bolt may be forced back by any pressure applied to its end, a pressure which may often easily be brought to bear. At the centre of the lock is seen the end of the key acting on a notch in the bolt, and surrounded by wards.

Some of the warded locks of the last century are curious. While the idea prevailed that a complicated ward gave security, there was room for the exercise of ingenuity in varying the shape of the wards. Fig. 10 is copied from the great French work. It represents the cuts in the key, and also the complicated forms of the pieces of metal which constitute the wards corresponding with those cuts. The aperture in the key at 16 fits upon the metal surrounding the keyhole at 18; and the M-shaped cuts at 17 fit in like manner upon the similarly-shaped metal pieces at 19.

Another example of a similar kind is shewn in fig. 11, where an anchor appears to have been the favourite form. The anchor cuts in the key are shewn at 26; while in the wards the bottom of the anchor is near the keyhole at 28, and the top at 29.

A similar illustration occurs in fig. 12, where the star-like cuts at 34 on the key correspond with the star-like wards at 33.

We are somewhat anticipating the full consideration of this subject; but it is desirable at once to explain how and why an improvement on the warded lock was sought for.

Besides wards, there have been numerous other contrivances for adding to the security of locks--including screws, escutcheons, spiral springs, wheel-and-pinion work, alarums, and multiple bolts. As these are not of sufficient importance to be treated in separate chapters, we shall here give just so much notice of them as will illustrate their general character. Some of them are found combined with the "tumbler" principle, presently to be described; but all of them, it is now well known, were employed in various, ways when the tumbler lock was but little understood, and when the warded lock was held in esteem.

The escutcheon has been a favourite resource with lock-makers. Mr. Mordan's escutcheon, for instance, introduced before the Society of Arts in 1830, is a contrivance to be placed temporarily over the keyhole of a door, to prevent the picking of the lock during the owner's absence. The escutcheon, or "protector," has a short pipe which, after the door has been locked, is thrust into the keyhole; attached to the pipe is a small lock, on Bramah's or any other convenient principle, so contrived that, on turning its key, two lancet-shaped pieces fly out laterally and bury themselves in the wood. The escutcheon cannot be removed until the small key has reacted upon the small lock; and until this removal has taken place, the large key cannot reach the keyhole.

A curious application of the escutcheon principle attracted some attention among locksmiths about seventy years ago. One of the first premiums awarded by the Society of Arts, after the commencement of their "Transactions," was to Mr. Marshall, for a "secret escutcheon," in 1784. In his description of his new invention, he adverts to the marquis of Worcester's wonderful escutcheon, and to the many attempts which have since been made to produce an apparatus which should realise the marquis's description. He supposes that the letter padlock originated as one among many varieties of these imitative inventions; but this may be doubted. Mr. Marshall's contrivance, however, was in effect an endeavour to improve upon the letter-lock. He considered it an objection that, in ordinary locks of this kind, the letter-rings admit of no variation of place; and he sought to remedy this defect. It is not so much a new lock, as an escutcheon for a lock, which he produced. There is a studded bar passing through a barrel; there are five rings which work concentrically on this barrel; there are letters on the outer surfaces of the rings, and notches on the inner surface; but when, by the usual puzzle-action of the rings, the notches in them have been brought into a right line with the studs of the bar, the result is, not that the hasp of a padlock is raised, but that the escutcheon is removed from the keyhole of an ordinary lock. Mr. Marshall's contrivance, therefore, is not so much a ring padlock, as a puzzle-ring security for the escutcheon of a fixed lock.

Some locks work by a screw and a spiral spring, instead of an ordinary key. Mr. W. Russell received a silver medal from the Society of Arts, about thirty years ago, for a new mode of locking the cocks of liquor-casks. Under ordinary circumstances, as is well known, the cock of a barrel or cask is in no way secure from the action of any one who can approach near enough to touch it; and different methods have been adopted of obtaining this security or secrecy. One plan is to employ a perforated cap, soft-soldered to the barrel of the cock, immediately over the grooved plug, the top of which plug is formed to the shape of the perforation, and a socket-key of the same form is introduced to turn the plug or open the lock. Another plan is to employ an iron saddle or staple, passing over the plug and below the bottom of the cock, through which a bolt is put, and a pendent padlock attached. The first method is very inefficient; the second is much superior, and has been largely adopted for locking the cocks of coppers, stills, vats, and other large vessels. But Mr. Russell thought some further improvement wanted. He caused a hole to be bored through the barrel, and to some depth into the plug when the latter is in the position for closing the cock. A stud works into this hole in such a way, that when the stud is driven home, the plug cannot be turned or the lock opened. The stud is attached at its other end to a spiral spring connected with a screw; a key is employed, the hollow pipe of which has an internal screw; and when this key is inserted in the cock-barrel and turned twice round, it draws back the stud, and allows the plug to be turned round in the proper way for opening the cock.

It is not often that wheel-and-pinion work is introduced into locks; the delicacy, the costliness, the weakness, and the tendency to get out of order, would all militate against the frequent adoption of such a course. It is, however, adopted occasionally. Mr. Friend's secret-lock, introduced to the notice of the Society of Arts in 1825, had a train of wheels which acted upon the bolt, driving it out whenever the circular arcs of three wheels moved against it, but allowing a spring to force it back again whenever a deep cleft in each of the wheels locked into a stud on the bolt. There were certain numbers on a guide-plate, and a power of combining these numbers in great variety; and a provision that the bolt could be unlocked only by the same combination of numbers which had locked it. The guide-plate was a separate piece of apparatus, carried in the pocket of the user as a companion to the key. The key was of no use without the guide-plate, nor the guide-plate without the key. The user 'set' the numbers on the guide-plate, then applied it to the face of the lock, then introduced the key into the key-hole, and turned the key partially round; the bolt was now shot, and the guide-plate removed. If the key were used without the guide-plate, the bolt might be locked, but it was always unlocked again by the time the key had made a complete circuit. There was considerable ingenuity in the idea of this lock; but we believe it never went further than a model. Indeed many of the locks elaborately described in books have never had an existence as acting working locks.

A curious alarum-lock was invented by Mr. Meighan, in 1836, in which the bell or alarum is not placed behind a door, as in many alarum contrivances, but within the lock itself. Two or more studs are placed on the bolt, which press against the lower end of a small tumbler; the movement of the tumbler elevates a hammer; but as soon as the point of the tumbler becomes released from the stud, a spring presses the hammer down forcibly, and causes it to strike against a small bell placed near it. This sounding of the bell will be repeated, during the shutting of the bolt, as many times as there are studs to act upon the point of the tumbler.

Much of the ingenuity which has been displayed in locks depends on the employment of multiple bolts, there being all the additional strength which results from the use of two or more bolts instead of simply one. Ordinary doors seldom afford us examples of these double bolts; but they may be frequently seen in cabinets and desks, where two staples fixed to the lid fall into two holes in the lock, and are retained by two bolts. The most remarkable and complicated varieties, however, are those in which the bolts, instead of shooting parallel and nearly together, shoot in wholly different ways; one up, one down, one to the right, one to the left, and so on. It is on safes, strong boxes, and the doors of strong rooms containing valuable treasures, that such locks are usually placed. The mechanism is such that the key acts upon all the bolts at once, through the intervention of levers and springs of various kinds.

If a lock can be picked, the picking is as effective whether the lock has one bolt or twelve bolts. This fact led Mr. Duce, in 1824, to construct, instead of a four-bolt lock, four distinct one-bolt locks, fixed in the same frame and opened by the same key; the bolts to be moved in succession instead of simultaneously. It would require four times as long to pick this as a four-bolt lock of similar action.

There have been many other varieties of the multiple bolt, but we need not stop to describe them.

ON TUMBLER, OR LEVER LOCKS.

This ingenious and very useful lock is represented, so far as regards its governing principle, in fig. 25. The bolt is here seen to have a peculiar slot or hole cut in it, consisting of a narrow horizontal passage or gating, with three notches above it and three below it. These double notches might be available even for one tumbler only; but Barron used two or more for the sake of additional security. In fig. 25 there are two tumblers shewn, expressed by dotted lines; both are hinged to one pivot, both are raised by the same action of the key, but the stump on the one tumbler does not coincide in position with that on the other. It will be seen that if the studs of the tumblers rested in the lower notches, they would require to be elevated to the level of the gating before the bolt could be moved; while, on the other hand, if lifted too high, the stumps would be caught in the upper notches, and would equally prevent the passage of the bolt, The tumblers are unequally wide; and the bitt of the key is stepped or notched in a corresponding way, that there may be one step fitted to act upon each tumbler. Mr. Barron also adopted the reverse arrangement of having the stump on the bolt, and the openings in the tumblers; so that the principle of his patent may be concisely expressed as being "an arrangement to allow a stump on the tumbler to pass through an opening in the bolt, or a stump on the bolt to pass through an opening in the tumbler."

A very elaborate tumbler-lock, patented 23d February, 1790, by Mr. Rowntree, contrasts remarkably with the simplicity of Barron's lock. Mr. Rowntree's lock consisted of tumblers combined with revolving discs or wheels. Its mechanism may be understood from the following description and engravings. The same letters refer to the same parts in the several figures.

We now proceed to notice the modern tumbler-lock. This was arranged by Bird, whose patent, bearing date 29th October, 1790, was for a series of four double-acting tumblers, differing in no respect from those patented by Barron, and closely resembling those in use at the present time in the best tumbler-locks. We will describe the modern tumbler-lock more particularly when we have gone through a few historical details on the subject.

Messrs. Mitchell and Lawton obtained a patent bearing date 7th March, 1815, for a lock in which were combined with the bolt and double-acting tumblers, a series of movable wards, and a revolving curtain for closing the key-hole. The action of the wards was peculiar. On introducing any key or instrument, and passing it round, a number of movable wards or pieces were thrown out so as to prevent the key from being turned back or withdrawn. It was necessary therefore to pass round the key so as to unlock the lock, and if that were not possible, as in the case of a false key being used, it was held permanently, and could only be released by destroying the lock, When the bolt was once shot, the wards were carried up so as to leave a clear passage for the key. This lock does not appear ever to have come into use, on account of the violence required in case a wrong key should be used either by accident or design.

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