Читать книгу Rudimentary Treatise on the Construction of Locks онлайн

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A curious application of the escutcheon principle attracted some attention among locksmiths about seventy years ago. One of the first premiums awarded by the Society of Arts, after the commencement of their “Transactions,” was to Mr. Marshall, for a “secret escutcheon,” in 1784. In his description of his new invention, he adverts to the marquis of Worcester’s wonderful escutcheon, and to the many attempts which have since been made to produce an apparatus which should realise the marquis’s description. He supposes that the letter padlock originated as one among many varieties of these imitative inventions; but this may be doubted. Mr. Marshall’s contrivance, however, was in effect an endeavour to improve upon the letter-lock. He considered it an objection that, in ordinary locks of this kind, the letter-rings admit of no variation of place; and he sought to remedy this defect. It is not so much a new lock, as an escutcheon for a lock, which he produced. There is a studded bar passing through a barrel; there are five rings which work concentrically on this barrel; there are letters on the outer surfaces of the rings, and notches on the inner surface; but when, by the usual puzzle-action of the rings, the notches in them have been brought into a right line with the studs of the bar, the result is, not that the hasp of a padlock is raised, but that the escutcheon is removed from the keyhole of an ordinary lock. Mr. Marshall’s contrivance, therefore, is not so much a ring padlock, as a puzzle-ring security for the escutcheon of a fixed lock.