Читать книгу Rudimentary Treatise on the Construction of Locks онлайн

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A curious alarum-lock was invented by Mr. Meighan, in 1836, in which the bell or alarum is not placed behind a door, as in many alarum contrivances, but within the lock itself. Two or more studs are placed on the bolt, which press against the lower end of a small tumbler; the movement of the tumbler elevates a hammer; but as soon as the point of the tumbler becomes released from the stud, a spring presses the hammer down forcibly, and causes it to strike against a small bell placed near it. This sounding of the bell will be repeated, during the shutting of the bolt, as many times as there are studs to act upon the point of the tumbler.

Much of the ingenuity which has been displayed in locks depends on the employment of multiple bolts, there being all the additional strength which results from the use of two or more bolts instead of simply one. Ordinary doors seldom afford us examples of these double bolts; but they may be frequently seen in cabinets and desks, where two staples fixed to the lid fall into two holes in the lock, and are retained by two bolts. The most remarkable and complicated varieties, however, are those in which the bolts, instead of shooting parallel and nearly together, shoot in wholly different ways; one up, one down, one to the right, one to the left, and so on. It is on safes, strong boxes, and the doors of strong rooms containing valuable treasures, that such locks are usually placed. The mechanism is such that the key acts upon all the bolts at once, through the intervention of levers and springs of various kinds.