It is necessary to draw a distinction between picking of a lock and ringing the changes on a permutating key; otherwise some of the late occurrences connected with locks can hardly be understood. After the reading of a paper by Mr. Hobbs before the Society of Arts, a discussion arose, in which it was stated that the Newell lock had been picked in London. Mr. Hobbs deemed it necessary to refute this statement. The report was circulated in many of the London newspapers; and Mr. Jeremiah Smith, the operator in question, supported it by his own statement. Under these circumstances Mr. Hobbs, on April 2, 1852, addressed a letter to the editor of the Observer; of which the following paragraph was intended to point out the distinction above mentioned between “picking” and “ringing the changes:”
“Early last autumn I lent to Mr. Potter, of South Molton Street, one of my locks, for the purpose of giving him an opportunity to make himself acquainted with its principle and construction. After he had had the lock in his possession several weeks, a report reached me that one of Mr. Potter’s workmen had picked my lock. I immediately called on Mr. Potter to ascertain the fact. Mr. Potter informed me that for the purpose of testing the possibility of opening the lock by means of an impression taken, or a copy being made of the true key, Mr. Smith had made a copy of the key by means of a transfer instrument, which instrument he shewed me at the time. After the key was made, it was tried, and found to lock and unlock the lock as readily as the original key. Mr. Potter then sealed the screws of the lock, changed the combination of the key, and locked it. Mr. Smith then took the lock, and with the key that he had made by copying the original, hit the combination, and unlocked it. The lock was of the smallest size, having but six tumblers; the number of changes that could possibly be made were 720. The time occupied by Mr. Smith, according to his own statement, was six hours and fifty-five minutes; this, allowing one minute for each change, would give him time to have made 415 out of the 720 changes before hitting the right one. I asked Mr. Smith why he did not use the original key instead of making a copy? His answer was, that ‘he could change the one he made faster, as he did not have to screw the bits in.’ Any person will readily understand the difference between ringing the combination of a key and picking a lock.”
In other words, the process was this: the operator had the true key, and might have used either this or one which he made from it. This would have sufficed for opening almost any lock ever constructed instantly; but in the American lock he had to find out which of 720 combinations was the right one, and he was employed almost seven hours in doing this. The exploit shewed patience, but had little bearing on the practical subject of lock-picking.
In March 1852 Mr. Smith put forth an offer to accept the challenge made by Mr. Hobbs in respect to the Exhibition lock. Mr. Hobbs agreed to the offer, and chose, as arbitrators on his part, Mr. Hensman, Engineer to the Bank of England, and Mr. Appold, inventor of the centrifugal pump which attracted so much attention at the Great Exhibition. Mr. Hobbs requested Mr. Smith to appoint arbitrators on his side also; but this was not done. Mr. Smith, at a meeting held by the four persons named, expressed a wish that an ordinary commercial lock should be the one experimented on, instead of the more complicated test-lock which had been at the Great Exhibition. This was a departure from the terms of the original challenge; but Mr. Hobbs waived his objection on this point, and offered to substitute a bank-lock with ten tumblers for the Exhibition lock with fifteen, the former being similar in construction but less complex. Another meeting was agreed upon, but Mr. Smith did not attend; and the matter was, by himself, brought to a sudden termination.
To shew the effect of difference in the number of tumblers and key-bits, we may state that, while, at a minute per change, it would take twelve hours to go through all the combinations with a six-bitted key, it would require seven years with a ten-bitted, and 2,500,000 years with a fifteen-bitted key! So much for power of combination, in the arithmetical mode of picking.
We now proceed to notice the violability of sundry minor locks. It might at first appear that the letter-lock is exceedingly difficult to pick; and so it unquestionably is, as long as we merely attend to the chance-medley trials by turning the rings round and round until we happen to hit upon the right combination. But there is another mode of solving the riddle, mechanical rather than arithmetical. A piece of common wire, bent in the form of the shackle, is put in between the ends of the lock; the spring or elasticity of the wire tends to force the ends apart; this causes the pins or studs on the rod to press against the inner edges of the rings. By trying all the rings in succession, some one of them will be found to bind or cling more than the others; this is turned round until the cessation of the bind shews that the notch in the ring has been brought into its right position relatively to the pin on the rod. Then another ring which binds more than the rest is treated in a similar way; until at length all the rings seem to be so far liberated as to indicate that the notches are in the right positions. In the dial-lock, similarly, when a pressure has been brought to bear upon the bolt in the right direction, a trial of the pointers will soon bring the notch in each wheel to the required position.
Some short time after the events in London connected with the lock controversy, Mr. William Brown of Liverpool described the letter-lock noticed in a former page, characterising it as a lock which he believed no one could pick. An incident in the history of this lock was thus narrated in one of the Liverpool newspapers. “Mr. Hobbs was taken by Mr. Milner to the office of Messrs. Brown, Shipley, and Co., and shewn this lock. The safe-door was closed and locked by the cashier at Mr. Brown’s request; and then Mr. Hobbs began to illustrate his views of the construction of the lock by manipulation and explanation, with which the subject of them appeared to sympathise so entirely and promptly that the door opened in a few minutes.”
In respect to the picking of the Egyptian lock, the main difficulty would be in obtaining any false key that would correspond with the pins of the lock; but this might be accomplished in a way analogous to that which is practised in many other cases. If a small piece of wax be laid on a blank key, the key inserted into the lock, and the blank pressed upwards against the pin-holes, there would be left an impression of those holes on the wax; this impression would furnish a guide to the fabrication of a false key. There is also very little difficulty in picking this lock by one of the ordinary instruments.
For the Yale lock, combining something like the pin-action of the Egyptian with the cylinder-action of the Bramah locks, the picking requires the use of an instrument that will fit between two of the pins, and to the outer end of which is attached a lever and weight; by this means a pressure is exerted upon the cylinder in the right direction for it to turn, and the pins are made to bind. Then, with another instrument, the pins are felt, and each one moved until it seems to be relieved from the bind: this indicates that the joint in the pin coincides with the joint between the two cylinders; and when all have been similarly treated, the weight acting on the inner cylinder will turn it. It is evident that this method is the same in principle as the one applicable to the Bramah lock.