Inventions in the Century

by William Henry Doolittle

“Loud as a bull makes hills and valley ring,
So roared the lock when it released the spring.”

The castles, churches and convents of the middle ages had their often highly ornamental locks and their warders to guard and open them. Later, locks were invented with complex wards. These are carved pieces of metal in the lock which fit into clefts or grooves in the key and prevent the lock from being opened except by its own proper key.

As early as 1650 the Dutch had invented the Letter lock, the progenitor of the modern permutation lock, consisting of a lock the bolt of which is surrounded by several rings on which were cut the letters of the alphabet, which by a prearrangement on the part of the owner were made to spell a certain word or number of words before the lock could be opened. Carew, in verses written in 1621, refers to one of these locks as follows:—

“As doth a lock that goes with letters; for, till every one be known,
The lock’s as fast as though you had found none.”

The art had also advanced in the eighteenth century to the use of tumblers in locks, the lever or latch or plate which falls into a notch of the bolt and prevents it from being shot until it has been raised or released by the action of the key. Barron in England in 1778 obtained a patent for such a lock.

Joseph Bramah, who has before been referred to in connection with the hydraulic press he invented, also in 1784 invented and patented in England a lock which obtained a world-wide reputation and a century’s extensive use. It was the first, or among the first of locks which troubled modern burglars’ picks. Its leading features were a key with longitudinal slots, a barrel enclosing a spring, plates, called sliders, notched unequally and resting against the spring, a plate with a central perforation and slits leading therefrom to engage the notches of the slides simultaneously and allow the frame to be turned by the key so as to actuate the bolt. Chubb and Hobbs of England made important improvements in tumbler locks, which for a long time were regarded as unpickable.

Most important advances have been made during the century in Combination or Permutation Locks and Time Locks. For a long time permutation or combination locks consisted of modifications of one general principle, and that was the Dutch letter lock already referred to, or the wheel lock, composed of a series of disks with letters around their edges. The interior arrangement is such as to prevent the bolt being shot until a series of letters were in line, forming a combination known only to the operator. Time locks are constructed on the principle of clockwork, so that they cannot be opened even with the proper key until a regulated interval of time has elapsed.

Among the most celebrated combination and time locks of the century are those known as the Yale locks, chiefly the inventions of Louis Yale, Jr., of Philadelphia. The Yale double dial lock is a double combination bank or safe lock having two dials, each operating its own set of tumblers and bolts, so that two persons, each in possession of his own combination, must be present at a certain time in order to unlock it. If this double security is not desired, one person alone may be possessed of both combinations, or the combinations may be set as one. In their time locks a safe can be set so as to not only render it impossible to unlock except at a predetermined time each day, but the arrangement is such that on intervening Sundays the time mechanism will entirely prevent the operation of the lock or the opening of the door on that day.

Another feature of the lock is the thin, flat keys with bevel-edged notchings, or with longitudinal sinuous corrugations to fit a narrow slit of a cylinder lock. To make locks for use with the corrugated keys machines of as great ingenuity as the locks were devised. In such a lock the keyhole, which is a little very narrow slit, is formed sinuously to correspond to the sinuosities of the key. No other key will fit it, nor can it be picked by a tool, as the tool must be an exact duplicate of the key in order to enter and move in the keyhole.

Of late years numerous locks have been invented for the special uses to which they are to be applied. Thus, one type of lock is that for safety deposit vaults and boxes, in which a primary key in the keeping of a janitor operates alone the tumblers or guard mechanism to set the lock, while the box owner may use a secondary key to completely unlock the box or vault.