If as the current alternates, the secondaries of the two branches are alternately short-circuited, the result will be that the currents of one sign pass over one branch and those of the opposite sign over the other.
The disadvantages of this arrangement which would seem to result from the employment of sliding contacts, is in reality very slight, inasmuch as the electromotive force of the secondaries may be made exceedingly low so that sparking at the brushes is avoided.
Figure 4 is a diagram partly in section of another plan of carrying out the invention.
The circuit B in this case is divided as before and each branch includes the coils of both the field and revolving armatures of two induction devices. The armatures O, P, are preferably mounted on the same shaft, and are adjusted relatively to one another in such manner that when the self-induction in one branch as C is maximum, in the other branch D it is minimum.
The armatures are rotated in synchronism with the alternations from the source A. The winding or position of the armature coils is such that a current in a given direction passed through both armatures would establish in one, poles similar to those in the adjacent poles of the field, and in the other, poles unlike the adjacent field poles, as indicated by n, n, s, s, in the drawing.
If the like poles are presented as shown in cir
