Safe
a receptacle for valuables, of iron or steel, or both combined. A safe to answer all requirements should be fire, explosive, acid, drill, and wedge proof. A fireproof safe need only be so constructed that, though exposed to the intense heat of a conflagration, its inner recesses remain at a sufficiently low temperature to prevent combustion of the contents. A burglar-proof safe needs many other safeguards, and the history of safe-making is mainly a record of struggles between the safe manufacturer and the burglar; the result is that safes can now be obtained which are all but impregnable. The safe consists of an outer and an inner wall, the space between being filled with some fire-proof material such as asbestos, silicate cotton, gypsum, etc. The outside casting, which may be single or compound, naturally receives the greatest attention, and various are the devices of manufacturers to render it sufficiently hard and solid to resist the finely tempered drills of the burglar. To prevent wrenching, the door is secured by bolts moving straight or diagonally into slots key fixes them in their positions. The first great improvements in locks, on one or on all sides. These bolts are moved by the door handle, and the lock key fixes them in their positions.
The first great improvements in locks, as applied to safes, are due to Chubb of London; but numerous patents, mostly of American origin, have been introduced.
Of these the keyless permutation locks deserve particular mention, as they obviate the danger which arises from lost or false keys. Such locks allow of opening only after an indicator has been moved ed in accordance with a certain combination of numbers arranged before closing the safe. Some safe locks are so constructed that to be freed they require different keys on different days, some can only be opened at a certain hour, this being fixed on before the door is closed; while others again require two or more keys in charge of different persons; in fact, the arrangements contrived to render the plundering of safes next to impossible are too numerous even to mention. The connection of safes with electric alarms in a variety of ways forms another safeguard.