Margaret Knight and the flat-bottomed paper bag

In the late 1860s Margaret Knight worked at a paper bag company in Massachusetts. Bags back then were flimsy envelopes. She designed a machine that folded and glued paper into the flat-bottomed bags we still use today.

While her iron machine was being built, a man named Charles Annan saw it and filed a patent first. Knight took him to court. Her hand-drawn plans, dated notes and wooden model proved the idea was hers, and she received U.S. Patent 116,842 in 1871.

The lesson for today's inventors: keep dated records of every sketch, version and test. Your design history is evidence. In Vault Forge, every revision of your design is saved with a date so you always have that trail.