PREFACE TO THE FIRST EDITION.
IN the following I am trying to give a short outline of those
phenomena which have become the most important to the elec-
trical engineer, as on their understanding and control depends the
further successful advance of electrical engineering. The art has
now so far advanced that the phenomena of the .steady flow of
power are well understood* Generators, motors, transforming
devices, transmission and distribution conductors can, with rela-
tively little difficulty, be calculated, and the phenomena occurring
in them xmcler normal conditions of operation predetermined and
controlled. Usually, however, the limitations of apparatus and
lines are found not in the normal condition of operation, the steady
flow of power, but in the phenomena occurring under abnormal
though by no means unfrequent conditions, in the more or less
transient abnormal voltages, currents, frequencies, etc.; and the
study of the laws of those transient phenomena, the electric dis-
charges, waves, and impulses, thus becomes of paramount impor-
tance. Iti a former work," Theory and Calculation of Transient
Electric Phenomena and Oscillations/' I have given a systematic
study of those phenomena, as far as our present knowledge per-
mits, which by necessity involves to a considerable extent the use
of mathematics. As many engineers may not have the time or
inclination to a mathematical study, 1 have endeavored to give in
the following a descriptive exposition of the physical nature and
meaning, the origin and effects, of those phenomena, with the use
of very little and only the simplest form of mathematics, HO as to
afford a general knowledge of these phenomena to those engineers
who have not the time to devote to a more extensive study,
and also to serve as an introduction to the study of 4I Transient
Phenomena." I have, therefore, in the1 following developed these
phenomena from the physical conception of energy, its storage and
readjustment, and extensively imed an illustrations oseillograms of
such electric discharges, waves, and impulses, taken on industrial
electric circuits of all kinds, an to give the reader a familiarity