This pin-tumbler type lock consisted of a vertical wooden housing containing several loose wooden pegs of different lengths. These pegs fitted into holes bored in the top of a wooden bolt, preventing the bolt from being moved and the door from being opened.
An oblique slot in the bolt provided access for a long wooden key with pegs of various lengths located on one surface and corresponding to the pegs in the vertical housing. When the key was inserted into the bolt and lifted, the pegs inside the housing lined up evenly at the top of the bolt, and permitting the door to be opened.
Specially designed large and heavy wooden key was shaped like modern toothbrush with pegs that corresponded to the holes and pins in the lock. This key could be inserted into opening and lifted, which would move the pins and allow security bolt to be moved.
During 1st millennia BC, locks finally started improving with the technologies and designs that were introduced by Greeks and Romans. Greek locks were commonly viewed as unsecure. They used a lock that worked by fastening the wooden bolt and staple to the inside of the door. The key was a sickle-shaped wooden or iron key manipulated and lift the bolt.
The ancient Romans built the first metal locks, and their iron locks and bronze keys are easily recognizable even today. They improved the Egyptian model by adding wards or projections or obstructions inside the lock that the key must bypass in order to work.
The Romans also invented the portable padlock with a U-shaped bolt which is known to have invented independently by the Chinese. Some Roman locks used springs to hold the tumblers in place, and the Romans made locks small enough that they could wear tiny keys on their fingers like rings.
The further development of the ward lock gave us padlocks. The Russians, Chinese, Turkish and East Indian used ornate metal padlocks which utilised all kinds of intricate designs.
In 1778, Robert Barron, invented the double tumbler lock. The tumbler is a lever that falls into a slot in the bolt thus preventing any movement, until picked up by the key to the height of the slot. This had to be done for each of the two tumblers at different heights, and then the key would slide the bolt. This innovation is still the basis of all lever locks.
In 1784, Joseph Bramah, displayed a lock to anyone who could pick it offering a prize of 200 guineas. In 1851, An American locksmith after trying for 51 hours was the first to open it and win the prize. In 1795, Bramah invented the hydraulic press, a check numbering machine and quill cutting machine to make the point or nibs of quills or pens.
In 1818 Jeremiah Chubb introduced an improved lever tumbler lock.
England had been the centre of innovations in lock-making for the past couple of centuries. It was Linus Yale Jr., son of an inventor & locksmith who started producing bank locks in a factory in Newport New York. He designed and patented the Yale infallible bank lock 1851.
His factory in Shelburne Falls Massachusetts became famous for its innovative bank locks. The Yale magic bank lock and the Yale double treasury bank lock/.
In 1861, he introduced combination lock. His most important invention was the cylinder lock based on ancient Egyptian design. In 1868 Linus and Henry Robinson Towne founded the Yale Lock Manufacturing Company and set-up a factory in Stamford Connecticut to produce cylinder locks.
In 1873, James Sargent of Rochester, New york patented a time lock mechanism that became the prototype of those being used in contemporary bank vaults. The time mechanism was concealed, utilizing as many as three clocks to cover a total of three days. The bolt was released, for the time the clocks were set to, and the safe then opened to the correct combination.
In 1916, Samuel Segal introduced first jemmy-proof lock and In 1924, Harry Soref in 1924 introduced first padlock.