Chapter III: Bit Key Locks
The next step in the evolution of locks was the invention of the lever or "bit". Here instead of wards we have levers with different "teeth" cut to specific levels. When the right key was inserted all of the levers would align in such a way that would allow the key to continue onwards to throw the bolt or the latch.
Unlike it predecessors this lock was born of the industrial age and many were available not only to the well to do but also to the masses thereby making home security available to all.