“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.”
In relation to the “first advantage” which Mr. Brown not unreasonably supposed to be possessed by his lock—viz. that “it cannot be picked, because it has no keyhole”—we shall have something to say in a future page, where certain fallacies on this subject will be noticed. In the meantime we may remark, that it is not a little creditable that a leading Liverpool merchant should have invented a lock worthy of occupying a position on his own safe for a quarter of a century; for we may be quite certain that he would not have allowed the lock to maintain that post of honour unless it had really (so far as experience had then gone) served worthily as a safeguard to his treasures. And if it were possible to collect all the by-gone specimens of lock-oddities, we should probably find among them many highly-ingenious letter-locks; for supposing a man to have a mechanical turn of mind, a lock is by no means an unworthy medium for displaying it; the pieces of metal are so small as to be easily manageable at a small work-bench in a small room. The fondness for this sort of employment evinced by the unfortunate Louis XVI. of France led to the common remark, “He is a capital locksmith, but a very bad king.”
In an amusing article in the Observer, during the progress of the “lock controversy,” was the following paragraph relating to combination-locks of the letter or puzzle kind: “The French, in their exposition of 1844, availing themselves of the permutation principle, produced some marvels in the art; but the principle has not been adopted in this country. The Charivari had an amusing quiz upon these locks when they first came out. It said the proprietor of such a lock must have an excellent memory: forget the letters, and you are clearly shut out from your own house. For instance, a gentleman gets to his door with his family, after a country excursion, at eleven o’clock at night, in the midst of a perfect deluge of rain. He hunts out his alphabetical key, and thrusts it into his alphabetical lock, and says A Z B X. The lock remains as firm as ever. ‘Plague take it!’ says the worthy citizen, as the blinding rain drives in his eyes. He then recollects that that was his combination for the previous day. He scratches his head to facilitate the movement of his intellectual faculties, and makes a random guess B C L O; but he has no better success. In addition to his being well wet, his chances of hitting on the right combinations and permutations are but small, seeing that the number is somewhere about three millions five hundred and fifty-three thousand five hundred and seventy-eight. Accordingly, when he comes to the three-hundredth he loses all patience, and begins to kick and batter the door; but a patrol of the National Guard passes by, and the disturber of the streets is marched off to the watch-house.”
CHAPTER IV.
WARDED LOCKS, WITH THEIR VARIED APPENDAGES.
The more ordinary locks are of an oblong quadrangular shape. In nearly all of them, either a bolt shoots out from the lock, to catch into some kind of staple or box, or a staple enters a hole in the edge of the lock, and is there acted upon by the bolt. A common room-door lock will illustrate the first of these kinds, a tea-caddy lock the second. The key, as is well known, enters a receptacle made for it; and the shaft of the key generally serves as a pivot or axis around which the web or flat part of the key may move in a circular course. During this movement the web acts directly or indirectly on the bolt, driving it in or out according to the direction in which the key is turned; the key impels the bolt one way, certain springs act upon it in another, and the balance between these two forces determines the locking and unlocking of the bolt. Wards, or wheels, are contrivances for rendering the opening difficult without the proper key; and it is of warded locks that we shall chiefly treat in this chapter.
fig. 6. Interior of a back-spring warded lock.
The annexed cut, [fig. 6], represents the interior of an ordinary back-spring lock, without tumblers. Such a lock may usually be known from a tumbler-lock by this simple circumstance, that it emits a smart snapping noise during the process of locking, occasioned by the pressure of the spring when the bolt is in a particular position. In the woodcut the bolt is represented half out, or half shot. At a a are two notches on the under side of the bolt connected by a curved part; b is the back spring, which becomes compressed by the passage of the curve through a limited aperture in the rim c c of the lock. When the bolt is wholly withdrawn, one of the notches a rests upon the rim c c; and the force with which the notch falls into this position, urged by the spring b, gives rise to the snapping or clicking noise. When the bolt is wholly shot, the other notch rests in like manner upon the edge of the aperture in the rim.
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.