William Dubilier (1888-1969) was an American inventor in the field of radio and electronics. He demonstrated radio communication at at Seattle's Alaska-Yukon-Pacific Exposition on June 21, 1909; ten years before the first commercial station operated. He was the first to use sheets of naturally occurring mica as the dielectric in a capacitor. Mica capacitors were widely used in early radio oscillator and tuning circuits because the temperature coefficient of expansion of mica was low, resulting in very stable capacitance - mica capacitors are still used where exceptional temperature stability is needed.
-  History Link.org