Telephones and telegraphs: 1902 : [and Municipal electric fire alarm and police patrol systems] (1906)
United States. Bureau of the Census, Steuart, William Mott, 1861-, Martin, Thomas Commerford, 1856-1924, Abbott, Arthur Vaughan, 1854-, Mayer, William · Washington : Govt. Print. Off. · leaf 78
tchboard. For continental United States thenumber of switchboards reported as belonging tocommercial systems was 9,954, or 91.4 per cent of thetotal number, while the mutual systems had 942boards, or 8.6 per cent. All the private branchexchange boards, 7,883, were reported for the com-mercial… … CENTRAL AUTOMATIC EXCHANGE, GRAND RAPIDS, MICHIGAN, 6,000 LINE FULL AUTOMATIC.
Telephone · Telegraph · Fire alarms
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