An Experiment on Electricity

Between 1746 and 1752, Benjamin Franklin turned a Philadelphia parlor into a laboratory. Working with a glass globe, a Leyden jar and a circle of friends, he established that electricity was a single fluid with positive and negative charges, coined the terms still used for it, and reasoned that lightning was the same thing on a larger scale. His letters to Peter Collinson in London were published in 1751 as Experiments and Observations on Electricity and made him the best-known American in Europe. The kite came later, in 1752.

Joseph Wright of Derby painted An Experiment on a Bird in the Air Pump in 1768; it hangs in the National Gallery in London. A traveling lecturer pumps the air from a glass bowl while a family watches the bird inside it fail, and Wright lights the whole scene from one hidden source on the table, so that every face becomes a different answer to the same question.

Franklin stands where the lecturer stood, drawing a thin blue spark from the cap of a Leyden jar with a brass rod. At the left a young man cranks the glass globe, and an older man in black watches from the corner. At the right a boy reaches for the jar, a girl hides her face, a woman keeps a hand on each child, and a gentleman in blue rests his chin on his fist. One candle lights the table, a key lies on the cloth, and lightning splits the window.

Wright painted the moment a room understood that the natural world could be questioned and would answer. Franklin spent the rest of his life asking.