Joint Author of "Telegraphy," "A Manual of Telephony," etc.--

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LOUIS BELL, Ph.D.
Consulting Electrical Engineer; Lecturer on Power Transmission,
Massachusetts Institute of Technology.
Author of "Electric Power Transmission," "Power Distribution for Electric
Railways," "The Art of Illumination," "Wireless Telephony," etc.

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OLIVER HEAVISIDE, F.R.S.
Author of "Electro-Magnetic Theory," "Electrical Papers," etc.

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SILVANUS P. THOMPSON, D.Sc, B.A., F.R.S., F.R.A.S.
Principal and Professor of Physics in the City and Guilds of London
Technical College.
Author of "Electricity and Magnetism," "Dynamo-Electric Machinery,"
"Polyphase Electric Currents and Alternate-Current Motors,"
"The Electromagnet," etc.

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ANDREW GRAY, M.A., F.R.S.E.
Author of "Absolute Measurements in Electricity and Magnetism."

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