Page:A Dissertation on the Construction of Locks (1815).pdf/36

 would depend on the application of a principle, as dissimilar as possible, to that, by which other projectors had in vain sought to attain perfection in the art of Lock-making. And as nothing can be more opposite in principle to, than a Lock which derives its properties from the motion of all its parts, I determined, that the construction of such a Lock, should be the subject of my experiment.—In the prosecution of this purpose, various models were constructed; and I had the satisfaction to receive from the least perfect of them, the clearest demonstration of the truth and certainty of my principle, which has now been confirmed by a long and extensive trial. The exclusion of wards, made it necessary to cut off all communication between the key and the bolt; as the same passage, which in a Lock simply constructed, would admit the key, might give admission likewise to other instruments. The office, which in other Locks is performed by the extreme point of the key, is consequently here assigned to an internal contrivance, which cannot operate upon the bolt till every part of the Lock has undergone a change of position. The necessity of this change to the purposes of the Lock, and the utter impossibility