Margaret E. Knight was an ingenious woman. She started tinkering with things when she was still just a tiny child, and the first invention that really improved the lives of those around her came about at the age of 12.
Research:

Percy Fawcett, Manuscript 512, and a Lost City in the Amazon, Pt. 2
37:10

Percy Fawcett, Manuscript 512, and a Lost City in the Amazon, Pt. 1
34:05

SYMHC Classics: Swill Milk
39:22