oth that he designed the following very ingenious system. By this
system he can obtain as small a difference of phase as desired,
without increasing the number of wires above three, a statement which
might at first seem paradoxical.

Before explaining this ingenious system, it might be well to call
attention to a parallel case to the above in continuous current
machines and motors. The first dynamos were constructed with two
commutator bars. They were soon found to work much better with four,
and finally still better as the number of commutator bars (or coils)
was increased, up to a practical limit. Just as the pulsations in the
continuous current dynamos were detrimental to proper working, so are
these pulsations in few-phased alternating current motors, though the
objections manifest themselves in different ways--in the continuous
current motors as sparking and in the alternating current motors as
detrimental inductive effects.

The underlying principle of this new system may be seen best in Figs.
4, 5, 6, 7 and 8. In Fig. 4 are shown two currents, I_{1} and I_{2},
which differ from each other by an angle, D. Suppose these two
currents to be any neighboring currents in a simple rotary current
system. Now, if these two currents be united into one, as shown in the
lower part of the figure, the resulting current, I, will be about as
shown by the dotted line; that is, it will lie between the other two
and at its maximum point, and for a difference of phases equal to 90
degrees it will be about 1.4 times as great as the maximum of either
of the others; the important feature is that the phase of this current
is midway between that of the other two. Fig. 5 shows the winding of a
cylinder armature and Fig. 7 that, of a Gramme armature for a simple
three-phase current with three leads, with which system we assume that
the reader is familiar.

[Illustration: FIG. 4.]

[Illustration: FIG. 5.]

[Illustration: FIG. 6.]

[Illustration: FIG. 7.]

[Illustration: FIG. 8.]

The two figures, 4 and 5 (or 7), correspond with each other in so far
as the currents in the three leads, shown in heavy lines, have a phase
between those of the two which compose them. Referring now to Fig. 6
(or 8), which is precisely like Fig. 5 (or 7), except that it has an
additional winding shown in heavy lines, it will be seen that each of
the three leads, shown in heavy lines, is wound around the armature
before leaving it, forming an additional c