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On the Construction of Locks and Keys by John Chubb
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24 CONSTBUCTTON OF LOCKS AND KEYS.
the safe, and the instrument was fixed. The large screw D was then withdrawn to fit the bar F into the socket at its end, and by applying the lever E to the head of the screw D, the bar F was forced steadily onwards, until either the lock was broken, or the door was burst open.
As this instrument had the power of lifting three tons weight, it was evident that some part of the door must give way under its pressure; and, in doors made on the common principle, the lock and a portion of the lock-case must be torn away, then by throwing back the bolts, the contents of the safe were in the power of the burglars.
Since the occurrence of the before-mentioned accident, Mr. Chubb had adopted the plan, in his recent safe locks, of cutting a square piece out at the back of the keyhole, and refixing it only by small screws, so that on the application of the " Jack-in-the-Box," that piece only was removed. He produced a lock constructed in this manner which had been so operated upon ; the plate had been forced away, leaving the lock and bolts, and thus the burglars were baffled in their attempt.
Mr. FAREY observed, that the mechanism of locks had been a favourite subject with him, from an early period of his studies, when he had the good fortune to be intimate with Mr. Joseph Bramah, and had acquired a knowledge of his locks, which were then in high repute. The secret workshops, wherein the locks were manufactured, contained several curious machines, for forming parts of the locks, with a systematic perfection of workmanship, which was at that time unknown in similar mechanical arts. These machines had been constructed by the late Mr. Maudslay, with his own hands, whilst he was Mr. Bramah's chief workman.
The important part of Bramah's lock was the central hollow part, called its revolving barrel, with steel locking sliders, to receive the end of the key. On looking into this barrel, the narrow ends of the six steel sliders could be plainly seen, all radiating from the centre pin; at the end of the key, there were six corresponding radiating notches, but the length of each notch was different.
In using the lock, the key was first pushed endways into the barrel, as far as it would go, when it was felt to be entering in opposition to a spring. The key acted against all the six sliders at once, but it pushed back each slider to a different distance, according to the lengths of the several notches in the key, which were just suitable for placing each one in, what might be called, its unlocking position; and all the six sliders being so placed at the same time, they would leave the barrel at liberty to be turned round by the key; the bolt of the lock was shot by a curious crank-pin motion,
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On the Construction of Locks and Keys by John Chubb