84

INVENTIONS OF NIKOLA TESLA.

tendency to rotation will be maintained if the maximum mag-netic attractions or conditions in both armature and field coincide,the energy developed by a motor being measured by the productof the magnetic quantities of the armature and field.

To secure this coincidence of maximum magnetic effects, Mr.Tesla has devised various means, as explained below. Fig. H8 isa diagrammatic illustration of a Tesla motor system in which thealternating currents proceed from independent sources and differprimarily in phase.

a designates the field-magnet or magnetic frame of the motor;

Fig. 69.

b b, oppositely located pole-pieces adapted to receive the coils ofone energizing circuit; and c c, similar pole-pieces for the coilsof the other energizing circuit. These circuits are designated,respectively, by n e, the conductor n" forming a common returnto the generator o. Between these poles is mounted an armature—for example, a ring or annular armature, wound with a seriesof coils e, forming a closed circuit or circuits. The action oroperation of a motor thus constructed is now well understood.It will be observed, however, that the magnetism of poles b, for