THOMAS A. EDISON
Pioneer Electrical Investigator and Inventor of Numerous Telegraph, Telephone, Lighting, and Other Electrical Devices.
Cyclopedia
of
Telephony and Telegraphy
A General Reference Work on
TELEPHONY, SUBSTATIONS, PARTY LINE SYSTEMS, PROTECTION, MANUAL
SWITCHBOARDS, AUTOMATIC SYSTEMS, POWER PLANTS, SPECIAL
SERVICE FEATURES, CONSTRUCTION, ENGINEERING,
OPERATION, MAINTENANCE, TELEGRAPHY, WIRELESS
TELEGRAPHY AND TELEPHONY, ETC.
Prepared by a Corps of
TELEPHONE AND TELEGRAPH EXPERTS, AND ELECTRICAL ENGINEERS OF
THE HIGHEST PROFESSIONAL STANDING
Illustrated with over Two Thousand Engravings
F O U R V O L U M E S
CHICAGO
AMERICAN SCHOOL OF CORRESPONDENCE
1919
COPYRIGHT, 1911, 1912,
BY
AMERICAN SCHOOL OF CORRESPONDENCE
COPYRIGHT, 1911, 1912
BY
AMERICAN TECHNICAL SOCIETY
Entered at Stationers' Hall, London
All Rights Reserved