JOHN PRICE JACKSON, M.E.
Professor of Electrical Engineering, Pennsylvania State College.
Joint Author of "Alternating Currents and Alternating-Current Machinery."

* * * * *

AUGUSTUS TREADWELL, JR., E.E.
Associate Member, American Institute of Electrical Engineers.
Author of "The Storage Battery, A Practical Treatise on Secondary
Batteries."

* * * * *

EDWIN J. HOUSTON, Ph.D.
Professor of Physics, Franklin Institute, Pennsylvania; Joint Inventor
of Thomson-Houston System of Arc Lighting; Electrical Expert and
Consulting Engineer.
Joint Author of "The Electric Telephone," "The Electric Telegraph,"
"Alternating Currents," "Arc Lighting," "Electric Heating," "Electric
Motors," "Electric Railways," "Incandescent Lighting," etc.

* * * * *

WILLIAM J. HOPKINS
Professor of Physics in the Drexel Institute of Art, Science, and Industry,
Philadelphia.
Author of "Telephone Lines and their Properties."

[Illustration: A TYPICAL SMALL MAGNETO SWITCHBOARD INSTALLATION]