HARTLEY, DAVID, the younger (1731-1813), parlia mentarian, pamphleteer and inventor, the son of the above, was a fellow of Merton college, Oxford, and member of Parliament for Hull (Kingston-upon-Hull) from 1774-80 and from 1782-84. He gained fame about 1776 by a discovery intended to protect buildings against fire, and attracted important gatherings to his experiment-house on Putney Common, where an obelisk stands in his honour. He was the friend and correspondent of Benjamin Franklin, with whom he had many interests ; and he gave up the greater part of his political career to opposing the American War, speaking frequently and at length in the Commons, and publish ing in 1778 his vigorous Letters on the American War. He was appointed by the Fox-North ministry as a plenipotentiary to treat with the Americans in 1783, and signed the definitive treaty in Paris.
See G. H. Guttridge, David Hartley, M.P. (Univ. of California Press, 1926. With bibliography.)