LOCKS AND KEYS. Great ingenuity is shewn in the numerous modes of shooting or working the bolt, in locks. In some locks the bolt is projected by the action of a spring ; in others there are two or more bolts, one of which only is under the control of the key, the others being moved by handles ; while in another class of locks taro or more bolts are shot or projected by the action of the key alone. Padlocks are a kind of detached lock in which a curved bar of iron, pivoted to the lock at one end, may be passed through a staple, and then so secured by shooting the bolt into a cavity in its free end, which is inserted into the lock for the purpose, that it cannot be removed from the staples or links through which it has been passed.
By far the greater part of the almost innu merable ingenious contrivances for rendering locks inviolable may be classed under one of two systems of security. The first consists in the insertion in the lock of fixed obstacles, commonly called wards, which prevent the entrance of any key which is not formed with corresponding openings, so as to thread its way among them, and thus render the bolt inaccessible to any but the proper key. The second consists in the use of moveable impe diments (which in their most general form are called tumblers) to the motion of the bolt itself, the security arising from the difficulty of bringing these moveable impediments, by the use of any but the proper key, to the actual and relative positions necessary to allow free motion to the bolt. In many locks both of the above means of security are used.
The key of an ordinary lock consists of a cylindrical shank with a loop-shaped handle at one end, and a piece called the bit projecting from it at a right angle at or near the other end. The bit end of the shank is hollow or solid, according as the lock may be opened from one side only, or from two. The projec ting bit, after being introduced into the body of the lock through the key-hole, is turned round within the lock until it comes in contact with a part of the bolt which is so shaped that the bit of the key cannot pass it, to conplete its revolution, without shooting the bolt either backwards or forwards, as the case may be. When thus moved, the bolt is retained in its position by a spring, or some other means, until it is again moved by the reverse action of the key.
The varied and highly ingenious inventions of Chubb, Bramah, Mordan, and other lock makers, depend on various combinations of the above two contrivances, the ward and the tumbler, aided by peculiarities in the form of the key.
As a means of security somewhat differing from any of the above, and affording certain advantages peculiar to itself, we may notice the permutation or combination principle, of which the simplest application is in a kind of padlock often termed a puzzle-lock, which opens without a key, but is regarded rather as an ingenious toy than as an available substi tute for locks of the more usual construction.
Some locks have been made in which the action depends on the key being a powerful magnet. In others the difficulty of opening is increased by requiring a peculiar method of applying the key; but, in addition to the cir cumstance that the secret must be known to several persons, these contrivances have the disadvantage of being very inconvenient in use. In one invention a key with two bits, and requiring eight or nine distinct movements in the act of unlocking, is used with a double lock, capable of shooting two distinct bolts. Many contrivances have been effected for attaching an alarum to locks, by which the introduction of a false key should ring a bell or fire a pistol. But most of these contrivan ces are curiosities rather than conveniences. In the compound-locks for iron safes, which often throw out two or three bolts in every direction, that is to say, on each side, and towards the top and bottom of the door, these are usually but so many branches of four massive pieces of iron, capable of being simul taneously projected by a handle in the centre of the door, the actual lock being but small, and merely intended to move an apparatus by which the great bolts are themselves locked or held fast; so that the key need not bear any proportion to the magnitude of the bolts by which the door it secured.
A most complete series of loCki wag con structed, sortie years age, by the late Mr. Chubb, for the WeStminster Bridewell. It consists of about eleven hundred locks, forthing one series, with keys for the master, stib-master, and warders. At any time the governor has the power of stopping out the under keys, and in case of any surreptitious attempt being made to open a lock, and the detector being thrown, none of the tinder keyt Will regulate it, but the governor must be Made acquainted with the cirottrastalate, as he alone has the power, with hit key, to 'replace the lock in its original state. These locks, although they have been in constant wear ior sixteen years, are still in perfect condition.
Mr. Chubb, in An interesting vbrk on thit subject, remarks, The manufacture of locks and keys is Carried on, principally, at Wolver hampton, and the adjacent towns in Stafford shire, at well as in Birmingham and in Landon, and gives employment to thousands of persons. Besides the hoihe consumption, a large export trade is also carried on; and it is to know, that the use of the best locks, on which a great 'amount of labour is expended, is increasing, whilst greater attention has lately been paid to the style and character of the ornamental part's of both locks and keys." Mr. Chubb has lately produced A remark able specimen of lock-making. It is a gold finger-ring which instead of a stone contains a perfect padlock, on Chubb's patent principle, opening with its Miniature key, all made of gold, and capable of locking and unlocking ; the lock and key only weigh ten grains.