English portraitist and electricity researcher. Author of treatises on electricity, performed important experiments on Leyden jars, the electrical proprieties of tourmaline, and lightning rods. Fellow of the Royal Society, opposed Franklin's theories of electricity and claimed - contrary to the American scientist and statesman - that pointed lightning rods were less efficient than sphere-tipped rods. The argument also took on political connotations because of the crisis then raging between Great Britain and the American colonies.