The Conservation of Charge and the Practical Genius of the Lightning Rod. Richard Munson discusses how Benjamin Franklin was an endlessly busy experimenter who began his famous work by studying the Leiden jar, a rudimentary battery. Franklin conducted fundamental research and developed the law of the conservation of charge: the idea that positive and negative electrical charges always seek balance. On Christmas Day 1750, he exposed himself to danger by touching the terminals of two Leiden jars, which violently threw him across the room. In 1751, Franklin published his pamphlet, Experiments and Observations on Electricity Made in Philadelphia, America, which generated international fame before the kite experiment. Franklin sought a practical solution to the danger posed by lightning, and his experiment confirmed the connection between lightning and electricity, leading to the invention of the lightning rod, which became a great practical discovery saving lives and buildings. Franklin also invented the Franklin stove and refused a patent, viewing the invention as a public benefit. He pursued observation and experimentation with "joyfulness," viewing unexpected results as new possibilities.