Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 747
vedmethod up to date is that employed at Grand Rapids, the exchangein this city having a very large relative amount of toll work. All AUTOMATIC SWITCH-BOARD SYSTEMS. 725 lines, after passing through the distributing frame are led to a tollswitching section, where they terminate in cut-ofif jacks.… … FIG. 021.-SECTIUN OF AUTOMATIC SWITCH-BOARD, GRAND RAPIDS EXCHANGE. extends directly to the automatic apparatus, but when a jack isplugged at the toll section the portion of the line extending to theautomatic apparatus is cut ofif, and connection is made with theline at the toll board as in…
Telephone
Internet Archive · Cornell University Library · Public Domain Mark 1.0. Free to use for anything.
![An illustration from Telephones and telegraphs: 1902 : [and Municipal electric fire alarm and police patrol systems] (1906)](https://img.insideoutlibrary.com/img/200/ia-cu31924022817674-78-31.webp)
