No. 42, invented by Pierce in 1840, seems to be a carrying out of the plan suggested by the Marquis of Worcester in his Century of Inventions, where he says that “a lock may be so constructed that if a stranger attempteth to open it, it catches his hand as a trap catcheth a fox; though far from maiming him for life, yet marketh him so, that if once suspected he might easily be detected.” In Pierce’s lock a steel barb or sharp arrow-head is concealed below the key-hole, in such a manner that if any person in attempting to open the lock should over-lift the tumbler, the barb would be thrust by a spring into his hand. It is said that the patentee himself experienced the efficacy of this invention, by receiving the barb into his own hand.
No. 43, by Ruxton, patented in 1816, is furnished with a tell-tale, so arranged that if the tumbler be over-lifted in an attempt to pick the lock, a pin or catch is thrown out from the lock, which would be visible on opening the lock with the proper key. This invention preceded Chubb’s detector by two years, and would be entitled to some of the honours of originality were not Chubb’s arrangement much more simple and effective.
No. 44 is Bramah’s, the patent of 1784, and the crowning lock of the trophy, by which all the others are opened. Similar locks by Russell and Mordan are applications of the Bramah principle, with little or no variation.
No attempt has been made in these pages to describe every variety of lock that has been introduced. Several forms of puzzle locks, known as Russian and Chinese locks, have the forms of various animals, and they are locked and unlocked by pressing upon or moving some portion of the body of the animal: the security of such locks depends in many cases upon keeping the part to be pressed or moved secret. There are also various forms of alarum locks; but these do not greatly differ from common locks, except in having certain appendages, such as a pistol, which if loaded and properly adjusted, will be fired on any attempt being made to open the lock, either with its own key or some other instrument. Some locks are furnished with a bell or a rattle, which is rung or sprung on attempting to open the lock, and in this way the inmates of the house are informed of the attempt to effect an entrance. It will, however, be evident to any one who has read the preceding pages, that devices of this kind do not add to the security of the lock; they rather tend to degrade the art of the locksmith to that of the toyman. The locksmith, in common with every other artist, can only improve in his art by studying the principles upon which it rests, and illustrating them by the most approved examples which the constructive genius of his predecessors or contemporaries has furnished.
APPENDIX.
CHAPTER XIII.
ON AN IMPROVED CONSTRUCTION OF LOCK AND KEY.[12]
[12] By J. Beverley Fenby, Mechanical Engineer, of Birmingham. Extracted chiefly from the Proceedings of the Institution of Mechanical Engineers, 1866.
The simple fixed-guard or warded lock is so utterly worthless for security, no matter what amount of good workmanship be bestowed upon it, that it demands but short notice. It was contrived with the intention of making the passage to the bolt intricate; but it will be seen at once that this intricacy does not really offer any security. The wards of a lock are circular arcs of thin metal, so arranged as to require a key of peculiar pattern to pass amongst them, the shape of the cuts in the key being a section of the wards. To make a really complicated box of wards, and to cut keys which shall accurately fit their sweep, is a matter requiring considerable manual dexterity; and some warded locks are therefore expensive. But even with the best of them, all that it is necessary to do for opening the lock is to take a blank key which will properly fit the keyhole, coat it with wax, and then inserting it in the lock, press it round against the wards, which will cause them to leave an accurate impression of their section on the key. The parts impressed are then cut out with small files, drills, and saws, and the occasional use of fine cross-cut chisels. The key will then pass those wards which impressed themselves upon it; and if these are the only wards, it will go completely round and open the lock. If there are also other wards in addition, not brought up flush with the first wards, the key is waxed again and pressed against them, and then further cut out, as before. This process is evidently one of absolute certainty, and the key so made is in all respects as capable of mastering the lock as the original key.
These warded locks are however easily opened with merely a piece of bent steel wire,—bent into such a sweep as will reach right round the wards instead of passing amongst them, thus escaping all chance of being obstructed by them. Such an instrument is called by burglars a “twirl.”