Page:A Dissertation on the Construction of Locks (1815).pdf/46

 greater ingenuity exercised in the formation of it, than falls to the share of a common workman: for the key is not fitted to the Lock, but the Lock adapted to the key: and this is effected by means the most simple and easy, that can be imagined. The surfaces, expressed on the point of the key, are worked, as fancy may direct, without any reference to the Lock. The key being so completed, and applied to the surface of the sliders, a gentle pressure will force them to unequal distances from their common station, and sink their extreme points to unequal depths, in the space beneath the plate n, n. Whilst the sliders are in this position, the edge of the plate will mark the precise point at which the notch, on each lever, must be expressed. The notches being cut by this direction, the irregularity which must appear in their disposition when the sliders resume their station, and the inequality of the recesses expressed on the point of the key, will be as a seal, and its impression to each other.

Having thus endeavoured to give a just conception of the principle, I trust it will be perceived that the peculiar security of Locks constructed thereon consists in two points of excellence, namely, The infinitude of their variations, by