Electricity
Franklin's printing business was thriving in this 1730s and 1740s. He also started setting up franchise printing partnerships in other cities. By 1749 he retired from business and started concentrating on science, experiments, and inventions. This was nothing new to Franklin. In 1743, he had already invented a heat-efficient stove — called the Franklin stove — to help warm houses efficiently. As the stove was invented to help improve society, he refused to take out a patent.
swim fins
Among Franklin's other inventions are swim fins, the glass armonica (a musical instrument) and bifocals.
In the early 1750's he turned to the study of electricity. His observations, including his kite experiment which verified the nature of electricity and lightning brought Franklin international fame.