Experiments with Alternate Currents of High Potential and High Frequency | Page 4

led me to these advances--which even by
myself cannot be considered trifling, since they are so appreciated by
you--I believe that their real origin, that which started me to work in
this direction, and brought me to them, after a long period of constant
thought, was that fascinating little book which I read many years ago.
And now that I have made a feeble effort to express my homage and
acknowledge my indebtedness to him and others among you, I will
make a second effort, which I hope you will not find so feeble as the
first, to entertain you.
Give me leave to introduce the subject in a few words.
A short time ago I had the honor to bring before our American Institute
of Electrical Engineers[A] some results then arrived at by me in a novel
line of work. I need not assure you that the many evidences which I
have received that English scientific men and engineers were interested
in this work have been for me a great reward and encouragement. I will
not dwell upon the experiments already described, except with the view
of completing, or more clearly expressing, some ideas advanced by me
before, and also with the view of rendering the study here presented
self-contained, and my remarks on the subject of this evening's lecture
consistent.
[Footnote A: For Mr. Tesla's American lecture on this subject see THE
ELECTRICAL WORLD of July 11, 1891, and for a report of his

French lecture see THE ELECTRICAL WORLD of March 26, 1892.]
This investigation, then, it goes without saying, deals with alternating
currents, and, to be more precise, with alternating currents of high
potential and high frequency. Just in how much a very high frequency
is essential for the production of the results presented is a question
which even with my present experience, would embarrass me to answer.
Some of the experiments may be performed with low frequencies; but
very high frequencies are desirable, not only on 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 affinity. All these observations
fascinate us, and fill us with an intense desire to know more about the
nature of these phenomena. Each day we go to our work in the hope of
discovering,--in the hope that some one, no matter who, may find a
solution of one of the pending great problems,--and each succeeding
day we return to our task with renewed ardor; and even if we are
unsuccessful, our work has not been in vain, for in these strivings, in
these efforts, we have found hours of untold pleasure, and we have
directed our energies to the benefit of mankind.
We may take--at random, if you choose--any of the many experiments
which may be performed with alternating currents; a few of which only,
and by no means the most striking, form the subject of this evening's
demonstration: they are all equally interesting, equally inciting to
thought.
Here is a simple glass tube from which the air has been partially
exhausted.