FERRARIS, GALILEO (1847-97). An Italian physicist and electrical engineer. He was born at Livorno, Piedmont, and was educated at the University of Turin and the Royal School of Engineering in that city, from which he gradu ated as a civil engineer in 1869. In 1872 he received the degree of doctor of mathematics, and in 1879 he became professor of physics in the industrial museum and military college at Turin. devoting himself to the study of technical physies, lie was one of the foremost electricians in Europe, and was sent by the Italian Government as a delegate to various international electrical con gresses and exhibitions, and was president of the department of electricity at the exhibition held at Turin in 1884. At that time he was engaged in an investigation of electrical transformers with a view to determining their efficiency and other properties. In subsequent experiments many additional data from both the practical and theoretical standpoint were accumulated. and further investigations carried on in August and September. 1885. resulted in the discovery of the
rotatory magnetic field. This was produced by two alternating currents with a quarter differ ence of phase, and was in effect a revolving magnet in stationary apparatus. and made pos sible the two-phase motor. The investigation was described at length before the Royal Academy of Sciences of Turin. March 18. 1888. An important memoir by Ferraris, On the Difference of Phase of Cumnts, on the Lag of Induction and on the Waste al Encrgy in Transformers, was published in 1887. and treats thoroughly the subject in its many bearings. In 1893 he published a theory of the single-phase alternating motor and toward the end of his life he was engaged in devising apparatus to transform alternating currents. The part played by Professor Ferraris in the development of alternating currents cannot be overestimated, and his works are considered standards.