Читать книгу Rudimentary Treatise on the Construction of Locks онлайн

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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 In the first position, it can only be withdrawn by the key; in the second, it closes the door, but can easily be withdrawn by the handle; and in the third, it leaves the door unfastened.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.