Before standardization to the Edison socket, the following sockets were in use in the United States. Shown from top to bottom, and left to right: Siemens-Halske, Hawkeye, Italian, Westinghouse, single contact Ediswan, Brush-Swan, Schaefer, double contact Ediswan, Westinghouse, Perkins (or Mather), Weston, United States, Fort Wayne "Jenney", Edison, Edison, Thomson-Houston.