Читать книгу Rudimentary Treatise on the Construction of Locks - Dodd George - Страница 7

Table of Contents

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.

Locks, in truth, admit of an immense variety, which, however important to be known to locksmiths, carpenters, and others employed on them, need only be glanced at very cursorily by the general reader. Some locks are named according to the purposes to which they are to be applied; others according to their shape, or the principles of their construction. In the first place, there is the distinction between in-door and out-door locks. Of in-door locks, one principal kind is the draw-back lock, for street-doors, in which the bolt is capable of maintaining any one of three positions: it may be locked by the key, or left half-way out by the pressure of a spring, or be drawn back by a handle. In the first position, it can only be withdrawn by the key; in the second, it closes the door, but can easily be withdrawn by the handle; and in the third, it leaves the door unfastened. If these locks are made of iron and carefully finished, they are further called iron-rim; but if made of wood, suitable for back-doors and inferior purposes, they are spring-stock. For the doors of rooms, there are the iron-rim, the brass-case, and the mortise lock; the second supplants the first, and the third the second, as we advance in the elegance of the door-fittings. Other designations for room-locks depend on the number of the bolts: thus, if there be only one bolt, it is a dead lock or closet lock; if there be a second bolt, urged by a spring and drawn back by a handle, it is a two-bolt lock; and if there be also a third, a private bolt acting only on one side of the door, it is a three-bolt lock. Again, according to the kind of handle employed, it may be a knob lock or a ring lock. According to which edge of the door it is to be fixed, it becomes a right-hand or a left-hand lock. If the wards of the lock are of somewhat superior quality, and bend round nearly to a circle, the lock is one-ward round, two-ward round, and so forth. If the lock has no wards at all, it is plain; if the wards are of common character, they are often called wheels, and then the lock becomes one-wheel, two-wheel, &c. Sometimes the lock is named from certain fancied resemblances in the shape of the ward, as the L-ward, T-ward, or Z-ward. If the wards are cast in brass, instead of being made of slips of iron or copper, the lock is termed solid ward.

Of the numerous but smaller varieties known by the collective name of cabinet locks, there are the cupboard, the bookcase, the desk, the portable desk, the table, the drawer, the box, the caddy, the chest, the carpet-bag, and many other locks. All these locks are further called straight, when the plate is to be screwed flat against the wood-work; cut, when the wood is to be so cut away as to let in the lock flush with the surface; and mortise, when a cavity is excavated in the edge of the door for the reception of the lock.

Out-door locks are usually wooden stock locks, for stables, gates, &c.; comprising many varieties of Banbury, bastard, fine, &c. There are D locks and P locks, for gates, designated from their shapes; and there are the numerous kinds of padlocks.

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.

It is scarcely worth while to descant upon the “middle age” of lock-making—to impart to the subject so much of dignity as to be susceptible of regular historical treatment. True, we know that wards were employed before tumblers (unless, indeed, the pins of the Egyptian lock be considered as tumblers—a character to which they present considerable claim), and that wards may be taken as the representative of the medieval period of lock-making; but it may be more profitable to proceed in our notice of the different kinds of locks in an order which will in itself partake somewhat of the historical character.

Apart from all the warded and tumbler locks are the very curious puzzle or letter-locks; a construction which we propose to dismiss out of hand in the present chapter, before treating of those which have more commercial importance.

The puzzle-lock is generally in the form of a padlock, which is opened and closed without the use of a key, and which has certain difficulties thrown in the way of its being opened by any one who is not in the secret of the person who closed it. It is, in fact, one of the locks in which the doctrine of permutation is made to contribute to the means of security. The key to open it is a mnemonic or mental one, instead of one of steel or iron. Two centuries ago, the puzzle-lock attracted far more attention than any other. It has always certain movable parts, the movement of which constitutes the enigma. Some of these very curious and out-of-the-way locks are so formed as to receive the name of dial-locks; but the chief among them are ring-locks—a name the meaning of which will be presently understood.

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 (or a considerable number of them) 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 LOCK 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.

There are many allusions to locks, apparently belonging to the letter or puzzle principle, in authors who flourished two or three centuries ago. Thus, in Beaumont and Fletcher’s play of the Noble Gentleman, written in the early part of the seventeenth century, one of the characters speaks of