Chicago Safe & Lock, Co., Chicago, Illinois - 2 movements - Gem model paired with James Sargent's Rollerbolt Magnetic combination lock

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On March 19, 1885 the Chicago Safe & Lock Company located at 209-217 South Canal Street in Chicago (currently the site of a high rise building; Chicago is this author's home town), introduced their first time lock. The first order from the E. Howard Company was for one-hundred units numbered from 500 to 600. This company had recently acquired the services of Henry Gross who was a key employee and inventor at the Hall safe & Lock Company. His patents, especially that of February 8, 1876 formed the basis for that company's line of time locks. Gross left Hall over disputes over patent royalty payments. Later that year on December 11th Chicago Safe & Lock Company placed an order with E. Howard for twenty new dials that bore the marking Gem Time Lock Co., Gross Patents, Chicago, Ills. Thanks to this change, possibly an attempt to avoid lawsuits, this lock is known as the Gem time lock. This author has seen a few other examples of this lock but none have this designation on the dial. (1) The example shown here is serial number 501 making it the earliest known example and could be the first lock installed by this short-lived company. A more detailed examination of the Gem time lock can be found here.

On this page we will examine in more detail the James Sargent Rollerbolt Magnetic combination lock. Throughout the nineteenth century, European financial institutions had equally well developed safe and vault technology as that of the United States. However, while European inventors continued to introduce innovative and elegant key locks, key lock development had substantially ended in the United states by the 1860's. The broad acceptance of the dial combination mechanism throughout the American safe and vault industry offered new security challenges to safecrackers. With no keyhole, safecrackers increasingly turned to drills, wedges, torches and the like, but those intent on defeating the combination lock found that early designs were vulnerable to new methods of attack. The image of the stethoscope-wearing safecracker is likely fictional, since even the earliest combination locks were not so loosely made that the fence could be heard on the tumbler gates. Rather safecrackers found that pressure applied to the bolt handle, forcing the bolt against the tumblers, allowed the manipulator to determine the tumblers' positions as the dial was turned. James Sargent refined this cracking technique in the mid 1860's through his invention of the micrometer (not to be confused with the instrument used in machining to make fine measurements used). His device used a weighted armature that attached to the bolt handle, thereby forcing the bolt against the tumblers. The micrometer could magnify even miniscule movements allowing all but the most exactingly machined locks to be opened. (2) See illustration below. Interesting how Sargent used a pocket watch dial layout instead of a decimal dial one might expect.


Using this objective test of the weakness of the then state-of-the-art combination locks, James Sargent developed and patented his magnetic lock on 1865, which instantly placed him among the foremost bank lock makers. Sargent's Magnetic Lock featured a powerful horseshoe-shaped magnet visible above the fence and fence bar. The magnet held the fence up, off the tumblers except for a small potion of the dial's rotation, making it nearly impossible for even a micrometer to distinguish the tumbler's positions. The Sargent Magnetic also introduced a new change key mechanism that required a second combination to be dialed in before the change key could be used to alter the combination. This combination-released change key mechanism would become an almost universal feature of high quality combination locks for the next century. Sargent's first model of the Magnetic Lock lock used a standard sliding bolt and was the first model combination lock Sargent marketed.

His second model introduced a year later in 1866 featured another significant feature, a rotating bolt or "rollerbolt" that moved the dogging action of the lock from the tumblers themselves to the fixed bolt axle, further isolating the tumblers from any attempt to read them through the boltwork. Sargent's combination of the magnetic mechanism, the combination-released change key and the rollerbolt made his second version one of the highest security combination locks ever made. The rollerbolt would be a major design element in Sargent's combination and later, time locks for many years. Sargent sold this lock in iron for $250 and in bronze as in the example illustrated here for $300. Five examples of this lock are known today. (3) See photos and video below for an explanation of the lock's operation.


The first photo shows the front plate secured and one can see the keyhole for the combination change key. The combination in this example is 50 L - 39 R - 15 L. Next a side view showing the rollerbolt in the 'off guard' or open position and the dial and tapered dial spindle. The tapered spindle was another anti-tampering design. If one attempts to force the lock with blows to the dial or overwhelming torque, the spindle will snap off rather than transmitting the force to the lock. The design is illustrated below.


The model 2 combination lock featured the rollerbolt for the first time. This was James Sargent's most important innovation and was later carried over to the time locks the S&G company produced, photos above. That design was later refined into the 'cello bolt' which remained a standard until after WWII. The magnetic system to hold the fence above the tumblers, another design to thwart lock manipulation was introduced in Sargent's first model of combination lock, and retained in this second version. The time lock shown is S&G's model 2; the first commercially successful time lock produced. This example the earliest known, s/n #49.


This video demonstrates the James Sargent Rollerbolt Magnetic combination lock paired with a Chicago Safe & Lock Co., Gem model time lock. The time lock dates from 1885. Both the time lock and this model of combination lock are quite rare. The combination lock is the second model made by James Sargent in 1866 and was produced one year before the partnership of Sargent & Greenleaf was formed in 1867 with Colonel Halbert Greenleaf. The time lock was later fitted to the combination lock around 1885.


The first illustration is from the original patent application for Sargent's magnetic lock. The second is an amended re-issue #4696 of the original patent six years later. These re-issues of patents in an effort to extend the patent life of a particular invention would eventually be overturned by the Supreme Court in 1889 from a case brought by Joseph Hall.

Gem model, 1885. 4 5/8"w x 3"h x 2 1/4"d, Case #17, movement pair #501, the Gem model serial numbering began at 500, making this the earliest known example; mounted to a James Sargent Rollerbolt Magnetic combination lock, 7 1/4"w x 5 7/8"h x 2"d, #298. file 262  


Illustrated above are papers contemporaneous to the when the lock was made in the mid 1860's. The first shows Sargent's model 2 Magnetic Rollerbolt lock, the same as in this example. Notice the difference in the decoration of the upper and lower plate shrouds. In the first picture they are simple holes, something this author has yet to see. The advertisement states that over five thousand of these locks are currently in use. This is highly unlikely as very few are extant. One can see the decorated plate shrouds as in this example as well as the way the combination lock was arranged on the safe door in conjunction with a S&G model 2 time lock. This combination lock is Sargent's Automatic, model 3 which did away with the magnet and used a series of three cams to perform the same function. Notice the use of the rollerbolt in both the combination and time locks. When both were simultaneously aligned with the door boltwork, the bolt could be moved into the two recesses and the safe door opened. A comment from this author on the movement of the time lock. The extensive skeletonizing of the front movement plate has been illustrated in some of the company's advertisements, but this style has never been observed in fact. This extensive fretting of the plate would make it more prone to violence of percussion or explosion and the first few production models did have some cutout design around the central section and under the two dials which was replaced a few years later with a solid plate for these reasons.  

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(1) American Genius Nineteenth Century Bank Locks and Time Locks, David & John Erroll, pp. 224

(2) American Genius Nineteenth Century Bank Locks and Time Locks, David & John Erroll, pp. 118

(3) American Genius Nineteenth Century Bank Locks and Time Locks, David & John Erroll, pp. 120