365. NIKOLA TESLA (1856-1943) American engineer and inventor who discovered the principle of a rotating magnetic field, invented the Tesla Coil and with Edison developed electric lighting. T.L.S. "N. Tesla", 1p. 4to., New York, May 13, 1896 to Paul Dana of the New York Sun. In part: "...I fear I could not manage to come to dinner...the experiments need some preparation and my time is so much taken up with other matters that I shall very likely need every moment..." Very good, matted with an engraving and brass plaque, set into a wood frame. In 1896, according to an interview he gave in 1916, Tesla invented a type of loudspeaker. The sounds were of about the same quality as telephones of that time, but the invention was never patented nor released publicly until years later. $500-700