Telephone crossbar switch, Swedish Ericsson, 1921
1921
1921
1920
1919
1920
1922
1923
1922-1923
1922-1923
1922-1923
1922-1923
1923
circa 1920
1934
2000-100 BCE
circa 1920
1955; 1830
1921
1923
circa 1920
1920
1920
1919
1990-96
1920
1923
1922-1923
1922-1923
1922-1923
1922-1923
1922-1923
1920-1922
1921
1920
1934
1922-1923
1922-1923
1923
circa 1919
1922
1903 (original); 1982 (model)
1772 (original); 1919 (model)
circa 1920
4000-2001 BCE
1922
1930 (replica); 1834 (original)
1923
1801-1892 (prepared); 1946 (element replaced)
1923
1923
1830 (original); 1967 (model)