412

INVENTIONS OF NIKOLA TESLA.

position to the passage through it of a wave of one sign, the othersecondary similarly opposes a wave of opposite sign. In conse-quence, the waves of one sign will, to a greater or less extent, passby way of one branch, while those of opposite sign in like man-ner pass over the other branch.

In lieu of saturating the primaries by a source of continuouscurrent, we may include the primaries in the branches c d, re-spectively, and periodically short-circuit by any suitable mechani-cal devices—such as an ordinary revolving commutator—theirsecondaries. It will be understood, of course, that the rotationand action of the commutator must be in synchronism or inproper accord with the periods of the alternations in order tosecure the desired results. Such a disposition is represented

Fig. 222.

C& o —s

diagraminatically in Fig. 222. Corresponding to the previousfigures, a is the generator of alternating currents, b b the line,and c d the two branches for the direct currents. In branch oare included two primary coils e e', and in branch d are twosimilar primaries f f' The corresponding secondaries for thesecoils and which are on the same subdivided cores j or j', are incircuits the terminals of which connect to opposite segments kk', and l i/, respectively, of a commutator. Brushes b b bearupon the commutator and alternately short-circuit the plates kand k', and l and i/, through a connection c. It is obvious thateither the magnets and commutator, or the brushes, may revolve.

The operation will be understood from a consideration of theeffects of closing or short-circuiting the secondaries. For ex-ample, if at the instant when a given wave of current passes, one