pondered over the beautiful phenomena which it disclosed to our
ravished eyes. So well known is this apparatus, so familiar are these
phenomena to every one, that my courage nearly fails me when I think
that I have ventured to address so able an audience, that I have
ventured to entertain you with that same old subject. Here in reality
is the same apparatus, and here are the same phenomena, only the
apparatus is operated somewhat differently, the phenomena are
presented in a different aspect. Some of the results we find as
expected, others surprise us, but all captivate our attention, for in
scientific investigation each novel result achieved may be the centre
of a new departure, each novel fact learned may lead to important
developments.

Usually in operating an induction coil we have set up a vibration of
moderate frequency in the primary, either by means of an interrupter
or break, or by the use of an alternator. Earlier English
investigators, to mention only Spottiswoode and J.E.H. Gordon, have
used a rapid break in connection with the coil. Our knowledge and
experience of to-day enables us to see clearly why these coils under
the conditions of the tests did not disclose any remarkable phenomena,
and why able experimenters failed to perceive many of the curious
effects which have since been observed.

In the experiments such as performed this evening, we operate the coil
either from a specially constructed alternator capable of giving many
thousands of reversals of current per second, or, by disruptively
discharging a condenser through the primary, we set up a vibration in
the secondary circuit of a frequency of many hundred thousand or
millions per second, if we so desire; and in using either of these
means we enter a field as yet unexplored.