Rudimentary Treatise on the Construction of Locks

by A. C. Hobbs; George Dodd

Before treating of lock controversies and lock violability in England, it will be desirable first to refer to America, where this subject attracted much attention some years earlier than the Great Exhibition—an Exhibition which will always be associated in a remarkable manner with the history of locks.

Soon after the inventions by Dr. Andrews and Mr. Newell, in 1841 (described in a former chapter), the rivalry between the two locks ran high; each lock being ‘unpickable,’ according to the estimate of its inventor. Mr. Newell thought the best mode of shewing the superiority of his own lock would be by picking that of his competitor; and after several trials, he succeeded in bringing into practical application that system of picking which we may designate the mechanical, as contra-distinguished from the arithmetical. Mr. Newell not only picked Dr. Andrews’ lock, but he wound up the enterprise by picking his own! He was probably the first person who honestly confessed to having picked his own unpickable lock. This discovery led Mr. Newell, as has been noticed in a former page, to the invention of the triple-action or parautoptic lock.

The mechanical principle, as applied to the picking of a tumbler lock, is nearly the same whatever form of construction be made the medium of experiment. When a pressure is applied to the bolt sufficient to unlock it if the tumbler-obstructions were removed, the edges of the tumbler bite or bind against the stump of the bolt, so as not to move up and down with such facility as under ordinary circumstances. By carefully trying with a small instrument each tumbler, and moving it until the bite ceases, the gating of that particular tumbler may be brought to the exact position for allowing the stump of the bolt to pass through it. (See [page 118].)

This violability is observable in the tumbler-locks under very varied forms of construction. Mr. Newell, after he had picked his own lock, devised a series of complicated wards, to add to the difficulty of reaching the tumblers; but he could not thereby get rid of the importance of this fact, that wherever a key can go, instruments of a suitable size and form could follow: his wards did not render his lock inviolable. His next contrivance was to notch the abutting parts of the primary and secondary tumblers, or the face of the stump and the ends of the tumblers; but this failed also. Mr. H. C. Jones, of Newark, N. J., added to all this a revolving pipe and curtain, to close as much of the key-hole as possible. But so far were all these precautions from being successful, that a lock provided with all these appendages, and affixed to the door of the United States Treasury at Washington, was picked. The makers of locks have, each one for himself, contended against such difficulties as were known to them at the time of inventing their locks; and, mortifying as failure may be, it would be cowardly to yield up the enterprise whenever any new difficulty presented itself. Difficulties, in locks as in other matters, are made to be conquered.

To shew how numerous are the sources of insecurity which have to be guarded against, to meet the skill often brought to bear upon this lock, we may adduce the reasons which led Mr. Newell to apply a curtain to the key-hole of his lock. Supposing the interior arrangement of the triple set of tumblers, and the metallic shielding wall, to be perfect, still, if the first set of tumblers can be seen through the key-hole, the following plan may be put in operation. The under-side of the tumblers may be smoked, by inserting a flame through the key-hole; and the key will then leave a distinct mark upon each tumbler the next time it is used, shewing where it began to touch each tumbler in lifting it. This may be seen by inserting a small mirror hinged into the lock through the key-hole. There may even be an electric light used from a small portable battery, to illumine the interior of the lock. By these and other means the exact length of each bit of the key may be determined; and from these data a false key may be made. It is to prevent this inspection of the works, or any other examination of an analogous kind, that the revolving curtain was applied; but, as stated in the last paragraph, even this did not suffice: ingenuity devised a mode of baffling the contrivance of curtains as well as that of the wards and false notches in the tumblers.

When the parautoptic lock was completed, it was keenly criticised in America, owing to the long discussions respecting the merits of previous locks. In a matter of this kind, where a commercial motive would lead bankers and companies to apply a very severe test to the security of locks and similar fastenings to strong-rooms and receptacles, any experiments made with their sanction became important. Mere letters or certificates emanating from individuals, expressive of opinions concerning a particular lock, would be out of place in a volume relating to locks generally; but it is quite within the limits of the subject, and has indeed become part of the history of locks, to notice experiments and attempts of a more public character. We may therefore introduce a few paragraphs of this description, relating to the career of the American lock in America itself.

The principal bankers at Boston (U.S.) held a meeting to take into consideration measures for testing the security of bank locks. Consequent on this meeting, Messrs. Day and Newell deposited five hundred dollars with the cashier of the State Bank at Boston, to be by him paid to any one who could pick the parautoptic lock: the trial was to be conducted under the auspices of the bank. One of the locks was brought to the bank, and was minutely examined by two machinists on two afternoons, after which it was secured to an iron chest, and locked by a committee appointed by the bank. The key was to remain in the hands of the committee during the trial; and it was to be used at their discretion, in unlocking and locking the door, without the knowledge of either of the other parties—provided that in so doing no alteration was made in the combination-parts of the key. Ten days were allowed to the operators for the examination and the trial; if they succeeded they were to have five hundred dollars; but if they injured the lock they agreed to forfeit two hundred, as a purchase price. At the end of the period the lock remained unopened and uninjured; and the two deposited sums were accordingly returned to the respective parties.

Messrs. Page and Bacon, of St. Louis, had a strong-room lock made by one of the chief locksmiths of that city. To test its security, the proprietors requested Mr. Hobbs to attempt to pick it; he did so, and succeeded. Whereupon the proprietors, having purchased one of the parautoptic locks, deemed it no more than fair play to subject this lock to a similar ordeal, an additional zest being given by a reward of five hundred dollars offered by Day and Newell to the successful picker. The maker of the former lock accepted the challenge; he was allowed to examine the new lock piecemeal, and was then allowed thirty days for his operations in picking. He failed in the enterprise. Of course, in this, as in all similar cases, the operator had not access to the true key.

It follows from the nature of this lock, as noticed in a former chapter, that when the bolt has been shot, if the bits of the key be re-arranged in any other form, the lock becomes to all intents and purposes a new lock, so far as that key is concerned, and cannot be unlocked unless the key revert to its original arrangement. To test this principle, a box with a parautoptic lock was placed in the room of the American Institute in 1845; it was locked; the bits of the key (12 in number) were then re-arranged, and the key was placed in the hands of any one who chose to try to open the lock—with the offer of a reward of five hundred dollars in the event of the lock being opened. Here, instead of the operator being called upon to devise new pick-lock implements, he had the actual key placed in his hands, modified however in such a way that, though the modifier could restore the original arrangement (provided he had kept some kind of record), the operator had numerous chances against his success. The lock remained unopened notwithstanding this challenge.

We shall have occasion to shew presently, that if the number of tumblers (and consequently the number of bits in the key) be small—not exceeding six, for instance—the possession of the true key gives any one the power of opening the lock, provided he has time and patience to go through a few hundred changes of the bits of the key; for, as some one arrangement must have been that by which the lock was locked, it must again occur if the user takes care to make all the arrangements in turn, and tries the lock after each. Whether this constitutes picking a lock, each lock-owner will decide for himself. All that it is at present meant to state is, that without access to the true key, the parautoptic lock has not hitherto been opened; and that with the true but altered key the process of opening is possible, but is slow and tedious.