rotation of the latter was, in this case, never quite satisfactory,
the experiment did not appear to be conclusive.

I have been unable to produce the phenomenon with the disruptive
discharge coil, although every other of these phenomena can be well
produced by it--many, in fact, much better than with coils operated
from an alternator.

It may be possible to produce the brush by impulses of one direction,
or even by a steady potential, in which case it would be still more
sensitive to magnetic influence.

In operating an induction coil with rapidly alternating currents, we
realize with astonishment, for the first time, the great importance
of the relation of capacity, self-induction and frequency as regards
the general result. The effects of capacity are the most striking, for
in these experiments, since the self-induction and frequency both are
high, the critical capacity is very small, and need be but slightly
varied to produce a very considerable change. The experimenter may
bring his body in contact with the terminals of the secondary of the
coil, or attach to one or both terminals insulated bodies of very
small bulk, such as bulbs, and he may produce a considerable rise or
fall of potential, and greatly affect the flow of the current through
the primary. In the experiment before shown, in which a brush appears
at a wire attached to one terminal, and the wire is vibrated when the
experimenter brings his insulated body in contact with the other
terminal of the coil, the sudden rise of potential was made evident.

I may show you the behavior of the coil in another manner which
possesses a feature of some interest. I have here a little light fan