Rudimentary Treatise on the Construction of Locks

by A. C. Hobbs; George Dodd

The combination-locks with keys have, with few exceptions, such an arrangement that a determinate number of movable parts (the so-called combination-parts) must by the turning of the key be raised or lifted into a certain position, if it is desired to project the bolt, or, what is the same thing, to lock it out; consequently these parts, or, as they are technically termed, tumblers, could not be transposed or changed, from the circumstance that the key-bit was one solid piece, with various steps or notches adapted to the several tumblers, and one impression from it destroyed the security of the lock.

In order, however, to add more security to such a combination-lock, and to make the key, in case it should be lost, or any counterfeit made from a wax impression, useless for an unlawful opening of the lock, another step was taken: the key-bit was made to consist of several bits or movable parts, in such a manner that the owner of the lock was enabled to change the bits, and to form, as it were, new keys different from the former. But since the bolt of the lock can only be projected whilst the combination parts or tumblers are in a certain position, which position depends upon the order of the bits in the key, it is evident that the owner, when changing the key, must at the same time make a corresponding change in the position of the tumblers in the lock itself, before the lock can be of any use for the newly changed shape of the key, which rendered it troublesome, and impracticable for the purpose designed, from the fact that no positive change could be made in the lock, without taking it from the door, and then taking the tumblers out of the case, to change them in a suitable form for the key.

This principle of changing the lock is rarely adhered to, as few men understand the machinery of a lock sufficiently to undertake the task; and this circumstance rendered the lock quite as insecure as the former one described.

Another step toward the perfection of combination-locks consisted in this, that the key remains unaltered whilst the combination parts of the lock can, before it is locked, be brought into different positions by means of movable plates on the frame of the lock. These plates were arranged by hand to certain figures, and depended on the memory for adjustment at each time the bolt was to be locked out or in, the key operating only on the bolt, to move it back and forth when the plates were set in proper positions for the purpose; and should the owner forget the arrangement of the plates, after projecting the bolt, his key is of no use to him, and he must resort to the skill of the locksmith to gain access.

The same case may occur in the far less perfect ring-lock of Reynier, which is operated without keys, and is opened by means of the rings being turned in a particular position; on these rings are usually stamped letters, which, by introducing some word readily suggested to the memory, thus point out the relative position of the rings.

But although in case of these ring-locks the owner is enabled to produce a change in the rings in such a manner that the opening of the lock can, as it were, only become possible by rightly arranging the altered position of the letters, still this lock of Reynier’s does not possess that safety and perfection which could have insured it universal application.

M. Crivelli, formerly professor at Milan, has given a minute description of the imperfection of ring-locks generally, in the annals of the Imperial Royal Polytechnic Institute.

It is the unanimous conviction of your committee that the American Lock of Newell surpasses, in the ingenuity displayed in its construction, all other locks heretofore known, and more especially in this, that the owner can, with the greatest facility, change at pleasure the interior arrangement of his lock to a new and more complex one, at every moment of his life, simply by altering the arrangement of the bits in the key, and this is accomplished without removing the lock or any part of it from its position on the door.

Its operation is as follows:—At the closing or locking of the lock, whilst the bolt is projecting, the movable combination parts assume precisely the position prescribed to them by the key, according to the particular arrangement of its bits at the time the key is turned.

The combination parts do not consist in one set of tumblers only, such as are found in all other locks, but there are three distinct sets or component parts fitting into each other. When the bolt is projected, it dissolves the mutual connexion of the constituent pieces, and carries along with it such as are designedly attached to it, and which assume the particular positions given them by the key in its revolution. These parts are rendered permanent in their given form by means of a lever adapted for the purpose, while the parts not united with the bolt are pressed down by their springs to their original places.