HOADLEY, John Chipman, civil engineer, born in Turin, New York, 10 December, 1818; died in Boston, Massachusetts, 21 October, 1886. He began his engineering career in 1836 on the preliminary survey for the enlargement of the Erie canal, and his ability soon won him promotion. After eight years of service in this line he became associated with Horatio N. and Erastus B. Bigelow in the construction and equipment of mills in Clinton, Massachusetts, devoting himself to the wide range of work necessary to build up a variety of industries. In 184S he established works with Donald McKay for the manufacture of locomotives and textile machinery in Pittsfield. Four years later he accepted the superintendency of the Lawrence machine-shop, after which he returned to the manufacture of engines. He invented the Hoadley portable engine, which was probably the first application of scientific principles to the design of high-speed engines, and which proved highly successful. For many years these engines had an extensive sale throughout the United States, and he continued their construction until 1873, when the business depression of that year determined the company to close up its affairs. Later he became interested in the organization of the Clinton wire-cloth company, agent of the New Bedford copper company, and of the McKay sewing-machine association. Subsequently to 1876 he was occupied chiefly as an expert in mechanical and engineering questions, serving in important cases in the courts and in responsible positions in the mechanical exhibitions. The professional work of Mr. Hoadley is shown by its influence over a wide range of engineering practice in mill-work, applications of steam, sanitary engineering, and methods of expert evidence, rather than in any massive structures. During the civil war he was sent to England by Massachusetts to inspect ordnance and examine fortifications for the purpose of devising a system for American sea-coast defences. He held various minor political offices, and was one of the original trustees of the Massachusetts institute of technology. For many years he was a member of the state board of health, and did much toward pro-rooting its efficiency. He was a member of several scientific societies, and contributed technical papers to their transactions, among the most important of which was his "American Steam-Engine Practice in 1884," read at the Montreal meeting of the British association for the advancement of science, which was the first step in the recent polemical engineering papers respecting English and American railway practice.