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On the Construction of Locks and Keys by John Chubb

Locksmithing, Blacksmithing, Metalcraft, Locks, Keys, Construction, Chubb, metalwork, security, antique, collectors, tools, education
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CONSTRUCTION OP LOCKS AND KEYS. 29 introduction of many wards. Somerford's lock had a series of tumblers, one half of which had to be pulled by the key out of the notches, and the other half to be pushed out with false notches on the other sides, to re-lock by any excess of motion. That lock had been favourably noticed many years back by the Society of Arts, and was one of the most perfect of the tumbler kind. Mr. Bra-mah's first locks had been picked, and the late Mr. Clements had picked a beautiful lock made by Jacob Perkins. The false notches, subsequently introduced by Mr, Bramah, added wonderfully to the security of his lock. With respect to the number of combinations of which locks were capable, it did appear to him that a certain limit should be assigned to it, in order to prevent any necessity for such close fitting, that rust, or dust on the key would prevent its opening the lock. A lock was exhibited some time back, the key of which had at first easily opened the lock; but when it was warmed the slight expansion caused by the heat prevented the key from acting on the bolts. Mr. HODGE said, that in America he had repeatedly seen impressions taken of locks having twelve, or fourteen tumblers; certainly they were not made by Mr. Chubb, but were such perfect imitations of his locks, having even the detector, that there did appear to be a possibility of picking these locks; in fact, he would undertake to bring a man from New York who would be capable of doing it. Mr. Mackinnon, after having succeeded in picking a tumbler lock, introduced an additional protection, which he termed a " curtain," made of a plate of case-hardened iron, three-quarters of an inch thick, radiating from the common centre of the lock, which prevented anything from reaching the tumbler, without first cutting through the curtain, which was next to impossible. The same gentleman had also made an expanding key, which was found to be very useful. Mr. Hodge had recently purchased at a sale, an old bookcase, which had been made in Geneva, about the year 1762, having a lock with a protecting curtain, though without the expanding key; this curtain revolved when the key was inserted. Mr. STEFHENSON, M.P., V.P., imagined, that though it might be possible to take a wax impression of a warded lock, such could not be taken from a tumbler lock, for there was nothing in a lock of the latter description which could give, by any injection of wax, a knowledge of the length of travel of the different tumblers. He therefore considered Mr. Hodge had raised a problem which did not admit of solution, and he would venture to say, that it was not possible to pick one of Chubb's locks by the aid of any wax impression.

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