Benjamin Franklin, American theorist on static electricity, mid-18th century.

Engraving by J Chapman of Benjamin Franklin (1706-1790). Franklin trained as a printer, first in his family's firm in Boston, and later in England. He became a notable publisher but is now better known as one of the founders of the science of electricity. He became interested in the principles of electricity in 1747 and published 'Experiments and Observations on electricity' in London in 1751. Below the portrait is an illustration of Franklin's experiment in conductivity; the wet string of a kite conducted electricity from a thundercloud and charged a large capacitor. This discovery enabled Franklin to invent the lightning conductor. Published by J Wilkes in 1806.