Switchblade knives were originally developed in the mid-18th century in Sheffield.
They’re known for their spring-loaded blades that are accessed with the push of a button.
Butterfly knives have two handles that conceal the blade until flipped around like the example posted above from the 1800s.
Sheffield, England became the epicenter of production.
The cost made them popular items with farmers and workers.
Romans were the next group to really use the pocket knife as a tool.
Many bronze “friction folders” have been discovered from the Roman Empire.
These knives didn’t have locks or springs, but rather used friction to stay closed and required pressure from the hand or thumb to stay open.