Door knobs have a very interesting history. Although it is difficult to provide an exact date of when door knobs first came into use, the first documentation of the invention of a door knob was in 1878. The U.S. Patent Office received a submission made for improvements on a door-closing device by an African American inventor named Osbourn Dorsey. Brass was one of the most popular materials because of its resistance to rust.
Door knobs are attached to a spindle, a metal shaft that turns the latch of the lock.
Modern “flat keys” were first introduced to the public by Linus Yale, Sr and Jr. in mid 1800s. By using tumbler lock and more sophisticated way of regulating the pins, these flat keys become an instant success across entire world. They were easy to manufacture, and thanks to invention of key cutting, easy to replicate in large numbers. Keys made from metals (iron, bronze, silver, gold) were often viewed as one of the most effective ways of publicly showing your wealth (only very rich people could afford to have personal safes or doors with locking mechanisms).