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On the Construction of Locks and Keys by John Chubb
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CONSTRUCTION OF LOCKS AND KEYS.
Mr. CHUBB produced specimens of Davis', Parsons', "Williams', and Nettlefold's locks, and gave a brief description of each.
Davis' lock was made with a double chamber, and had wards on the sides of the keyhole. The key was inserted into the first chamber, and turned a quarter round; it was then pushed forward into the inner chamber, where there was a rotating plate, containing a series of small pins, or studs, which were laid hold of by the key. By turning the key, the plate was moved round, the tumbler was raised, and the bolt shot backwards, or forwards. This lock was now used to some extent on the cabinet despatch boxes; but it was expensive, without affording any very great security.
In Parsons' lock, the tumblers were of a particular form, being hinged on a pivot in their centres, and worked into, and out of, two notches cut in the under side of the bolt.
Williams' lock consisted of a number of pins, similar to those in the Egyptian lock, and operated upon by a spring, in the same manner as Bramah's lock. On the pins being pushed down by the key to their respective positions, the bolt was set at liberty, and was pushed backwards and forwards by two springs, one of which was strong enough to overcome the resistance of the other, during the action of locking, and was forced back by the key, to allow the weaker spring to act in unlocking. It had, like Bramah's, Barren's, and Chubb's locks, the advantage of the over-lift; but it was liable to be easily deranged, and was much too delicate for general use. In 1845, a joint-stock company was projected, with a capital of
£30,000, for the purpose of working Williams' patent; but although the lowest amount of profit was estimated at £10,300 per annum, the shares were not taken up.
The peculiar feature of Nettlefold's lock (Fig. 10) was, that as Fig. 10. NETTLEFOLD'S LOCK.
the bolt was shot out by the key, two teeth, or quadrants, were projected from the sides of the bolt, which took a firm hold of the plate fixed on the door-post or edge. It was much used for sliding-
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On the Construction of Locks and Keys by John Chubb