Masolle 1921
Filed: November 28, 1921
U.S. Patent 1,550,381
Granted: August 18, 1925
Joseph Masolle, Hans Vogt and Josef Engl assignors to Tri-Ergon Ltd., of Zurich, Switzerland
"Electrostatic Telephone"
Referenced by Walker and Williamson in
U.S. Pat. 3,008,014.