AR´NOLD OF BRESCIA, an Italian religious and political reformer and martyr of the twelfth century. He was one of the disciples of Abélard, and attracted a considerable following by preaching against the corruption of the clergy. Excommunicated by Innocent II, he withdrew to Zürich, but soon reappeared in Rome, where he was taken and burned (1155).
ARNOLD-FORSTER, Hugh Oakeley, grandson of Dr. Arnold of Rugby, and adopted son of the late W. E. Forster, M.P., whose wife was his aunt, was born in 1855, died in 1909. He was educated at Rugby and University College, Oxford. He sat as member of Parliament for West Belfast from 1892, for Croydon from 1906, as a Liberal Unionist, was Parliamentary Secretary to the Admiralty from 1900 to 1903, then Secretary of State for War, a position which he held till Dec., 1905, having put forward sweeping proposals for the improvement of our army. He wrote on various subjects, especially books for popular instruction, including _How to Solve the Irish Land Question_, _The Citizen Reader_, _This World of Ours_, _Things New and Old_, _In a Conning Tower_, _A History of England_, _English Socialism of To-day_, _Military Needs and Military Policy_, &c.
AR´NON, a river in Palestine, the boundary between the country of the Moabites and that of the Amorites, afterwards of the Israelites, a tributary of the Dead Sea. It is now called Wady-el-Mojib.
AR´NOT, or AR´NUT, a name of the agreeably flavoured farinaceous tubers of the earth-nut or pig-nut (_Bunium flexu[=o]sum_ and _B. Bulbocast[)a]num_). See _Earth-nut_.
AR´NOTT, Dr. Neil, an eminent physician and physicist, was born at Arbroath, 1788, died 1874. Having graduated as M.A. at Aberdeen, he then studied medicine, and was appointed a surgeon in the East India Company's naval service. In 1811 he commenced practice in London. In 1837 he was appointed extraordinary physician to the queen. In 1827 he published _Elements of Physics_, and in 1838 a treatise on _Warming and Ventilation_, &c. He is widely known as the inventor of a stove which is regarded as one of the most economical arrangements for burning fuel, a ventilating chimney-valve, and his water-bed for the protection of the sick against bed-sores. In 1869 he gave £1000 to each of the four Scottish universities and £2000 to London University for the promotion of the study of physics. He was a strong advocate of a scientific as opposed to a purely classical education.