Page:A Dissertation on the Construction of Locks (1815).pdf/22

 me, that their testimony will do credit to the inventor, by confirming the efficacy, the infallibility, and the originality of the contrivance.

The principle on which all common Locks depend, is that of applying a lever to an interior bolt by means of a communication from without, which moves it in such direction as the lid, drawer, or door to be secured may require. The security of such Locks therefore, and their comparative excellence, are determinable by the number, variety, and disposition of the wards, or other impediments inserted in the passage, by which the lever or key is conveyed to the bolt; if these out-works do not secure the bolt from the intrusion and application of every instrument but its proper key, the Lock is inadequate to its intended purpose; and however intricate or difficult the passage to the bolt may be rendered by a skilful and judicious disposition of the wards; yet, if any access to the bolt is practicable by a workman of equal skill with its maker, the Lock is defective in the main point of excellence, which is effectual security, and is entitled to no higher claim than comparative merit.

The construction of Locks, is a subject on which many ingenious mechanics have employed their