FERREL'S LAW is to the effect that "If a body moves in any direction on the earth's, surface, there is a deflecting force arising from the earth's rotation, which deflects it to the right in the northern hemisphere and to the left in the southern hemisphere." This law was enunciated by William Ferrel, an American scientist, who was responsible for a number of papers,. of which his Essay on Winds and Currents of the Ocean (1856) is probably the best known. (See METEOROLOGY.)