account of the many effects secured by their use, but also as a
convenient means of obtaining, in the induction apparatus employed,
the high potentials, which in their turn are necessary to the
demonstration of most of the experiments here contemplated.

Of the various branches of electrical investigation, perhaps the most
interesting and immediately the most promising is that dealing with
alternating currents. The progress in this branch of applied science
has been so great in recent years that it justifies the most sanguine
hopes. Hardly have we become familiar with one fact, when novel
experiences are met with and new avenues of research are opened. Even
at this hour possibilities not dreamed of before are, by the use of
these currents, partly realized. As in nature all is ebb and tide, all
is wave motion, so it seems that; in all branches of industry
alternating currents--electric wave motion--will have the sway.

One reason, perhaps, why this branch of science is being so rapidly
developed is to be found in the interest which is attached to its
experimental study. We wind a simple ring of iron with coils; we
establish the connections to the generator, and with wonder and
delight we note the effects of strange forces which we bring into
play, which allow us to transform, to transmit and direct energy at
will. We arrange the circuits properly, and we see the mass of iron
and wires behave as though it were endowed with life, spinning a heavy
armature, through invisible connections, with great speed and
power--with the energy possibly conveyed from a great distance. We
observe how the energy of an alternating current traversing the wire
manifests itself--not so much in the wire as in the surrounding
space--in the most surprising manner, taking the forms of heat, light,
mechanical energy, and, most surprising of all, even chemical