Portrait painter, chemist, electrician. His portrait of Franklin (1759) now hangs in the White House Collection.

Involved in a long controversy with Franklin concerning the respective merits of rounded and pointed lightning rods. Served with Franklin on the committee to regulate lightning rods on St. Paul’s Cathedral (1769).

Published An Essay towards an Explication of the Phaenomena of Electricity …, the first of his numerous treatises on electricity (1746). Recognized as a leading British authority on electricity. Fellow of the Royal Society (1751). Joint author, with Benjamin Hoadly, of Observations on a Series of Electrical Experiments (1756). Received the Copley Medal (1760).

Appointed painter to the board of ordinance (1767).

Born in Leeds, where he first studied painting. Moved to London and worked as clerk to the registrar of the Charterhouse and established himself as a portraitist.