Business and Scientific Successes

Franklin's printing business was a financial success. The popularity of the Pennsylvania Gazette made him well known in Philadelphia and throughout the colonies. Even more popular, however, was Poor Richard's Almanack (so called from the pen name, Richard Saunders, under which it appeared). It sold about 10,000 copies per year. Franklin received so much work that he started printshops in several other cities. By 1748, at the age of 42, he had made enough money to retire. Franklin hoped to spend the rest of his life studying philosophy and investigating the natural sciences. He began to conduct various scientific experiments.

Franklin had been interested in the study of electricity since about 1746. He advanced the concept that electricity flows between two objects when one has a positive electrical charge and the other a negative electrical charge. Franklin suspected that lightning is electrical, and proved this in his kite experiment in 1752.

(For a description of this experiment )

The kite experiment led Franklin to invent the lightning rod to protect buildings from damage from lightning. Because of his achievements in the field of electricity, he was elected a fellow of the Royal Society, a scientific society in England, in 1756.

Franklin also compiled weather data, studied the seas, and worked on various inventions. He printed the first chart of the Gulf Stream in the Atlantic Ocean and investigated the effects of the Gulf Stream on sea travel. He devised the Franklin stove, a heating stove that operates on the same principle as a hot-air furnace. When his eyesight became poor, he invented bifocal eyeglasses for himself (1780).