How did Linus Yale Jr. develop the Yale cylinder lock?

Linus Yale Jr. developed the modern cylinder lock in the 1860s by adapting the pin-tumbler mechanism used by the ancient Egyptians.12

His design functions through a cylinder containing a series of pins. When a small, flat key with a serrated edge is inserted into the lock, the serrations lift these pins to specific, precise heights. Once all pins are aligned at the correct level, the cylinder is free to revolve, which allows the bolt to be withdrawn.12

This invention offered significant security through the vast number of possible pin-height combinations, further enhanced by the warding effect of the key's shape and the keyhole itself. Because of its efficiency and security, the Yale cylinder lock became one of the most widely used locking mechanisms in the world for buildings and automobiles.2