Subject
3 free books about locks and keys, free to read online. Chapter 1 of any book is free, no account needed.
Rudimentary Treatise on the Construction of Locks
Hobbs, A. C.; Dodd, George
On the Development and Distribution of Primitive Locks and Keys
Augustus Henry Lane-Fox Pitt-Rivers
Protection from fire and thieves: Including the construction of locks, safes, strong-rooms, and fireproof buildings; Burglary, and the Means of Preventing It; Fire, Its Detection, Prevention, and Extinction; Etc.
George Hayter Chubb
