shows a part of an iron door with a hole two inches in diameter cut through it. Fig 2 is the cutting tool used, and uninjured, as it was when taken from the machine after cutting the hole. Fig. 3 also shows a part of an iron door, having the patent improvement, upon which a trial was next made by the instrument with the same cutter. No impression, farther than taking a mere skin off the surface, could be made, and the cutter was utterly destroyed, as shown in fig. 4.
Another and more powerful machine was taken by the Manchester police, with cutters capable of making much larger holes, but the improvement is equally effective in destroying the tools.
Fig. 4
A third and more desperate mode of opening safes is by introducing gunpowder into the locks, destroying them, and thus opening the door with ease. This, however, has not lately been tried to any extent; the noise made is likely to lead to detection. It is rather a dangerous thing to try, and the locks of good safes have generally received such improvements as enable them to resist the shock of an explosion without injury.
There have been other methods said to be used by burglars to obtain their object, such as softening steel with a blow-pipe, so as to get a drill through it, or using drills made of diamonds, which are said to be very powerful, or employing acids to act upon and destroy hard steel, but I have not known of any burglaries proving successful by these means.
There is no doubt a vast amount of low ingenuity and cunning always at work, quietly scheming or planning the best mode of getting at the treasure so often kept in safes, and the only safeguard against this is to get the best safe possible, and then not to rely upon its being utterly impregnable (for no safe can be that), but to use ordinary watchfulness and care, so that it may not be exposed to unusual risks.