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the means by which the firſt impreſſion was obtained, enables the workman to proceed, till by the dexterous uſe of his file he hath effected a free paſſage to the bolt. And in this operation he is directed by an infallible guide: for, the pipe being a fixed centre on which the key revolves without any variation, and the wards being fixed likewiſe, their poſition muſt be accurately deſcribed on the ſurface of the bit which is prepared to receive their impreſſion. The key therefore may be formed, and perfectly fitted to the Lock, without any extraordinary degree of genius, or mechanical ſkill. It is from hence evident that endleſs variations in the diſpoſition of fixed Wards, are not alone ſufficient to the purpoſe of perfect ſecurity.
I do not mean to ſubſtract from the merit of ſuch inventions, nor to diſpute their utility and importance. Every approach towards perfection in the art of Lock-making may be productive of much good; and is at
