HYSTERESIS. If an unmagnetized iron bar be subjected to a gradually increasing magnetizing force, and the sponding values of the magnetic induction (flux density) in the iron be determined, then on plotting the magnetizing force against the induction a curve OBC is obtained. If now the netizing force is gradually creased to zero and the values of the magnetic induction mined, it will be found that the curve obtained does not coincide with OBC but takes the form CD. If now the direction of the magnetizing force is reversed, DEF is obtained, and decreasing the magnetizing force again to zero, reversing, and increasing will give the curve FGC. It will be seen from a study of the complete curve that the magnetic tion (flux density) lags behind the magnetizing force. It was to this property of magnetic materials that Ewing gave the name Hysteresis. (See MAGNETISM, ELECTROMAGNET, ELECTRIC GEN ERATOR, ETC.) .