Page:A Dissertation on the Construction of Locks (1785).pdf/59

 ſeen, that the poſitions, into which the levers are neceſſarily forced, by the preſſure of the key, in the operation of opening the Lock; can no more be aſcertained, when the key is withdrawn; than a ſeal be copied from its impreſſion on a fluid;—or the courſe of a ſhip be diſcovered, by tracing it on the ſurface of the waves. But inviolable ſecurity is not the only excellence they poſſeſs; the ſimplicity of their principle gives them likewiſe a great advantage over Locks, that are more complicated, in point of duration: for their eſſential parts being ſubject to no friction; nor expoſed to any poſſible accident from without; they will be leſs affected by uſe, and leſs liable to ſtand in need of repair.

The imperfections and defects, which are common, in ſome degree, to all other Locks, being thus remedied; and, the principle here adopted, being an infallible ſecurity, againſt the beſt directed efforts of the picklock, or any