Page:A Dissertation on the Construction of Locks (1815).pdf/47

 which the production of correspondent keys is avoided, however great the number of Locks may be, that are manufactured on any given scale. And the property of motion, which precludes all possible means of obtaining an impression of their interior parts, for the purpose of fabricating false keys. The former is capable of demonstration: the latter is self-evident.—The variations by which the production of correspondent keys is avoided, have two sources; the one, arising from the changes that may be made in the disposition of the sliders; the other, from the number of points contained on the projected surface of each slider, by which the position of its notch may in the smallest degree be varied.

The variations producible in the disposition of six figures only are 720, which being progressively multiplied by additional figures, will increase in astonishing degrees, and eventually show that a Lock, containing twelve sliders, will admit of