
Strowger step-by-step automatic telephone exchange switch, 1897-1898
1897-1898
1897-1898
1898
1801-1840 (original); 1901 (model)
2000-100 BCE
1901
1899
1901
1896
circa 1897
1896
1901
1896
1900
1872 (original); 1909 (model)
1955; 1830
1898
circa 1900
1898
1899
1901
circa 1900
1897
circa 1900
1898-1900
1900
1901
1898
1896
1898-1899
1901
1899
1900
1899
1899
1899-1901
1934
1901
1898
1900
1896
1897
1901
1900
1899
1901
1897
1897
1897
1775-1799 (original); 1900-1907 (model)
1839 (original); circa 1988 (replica)