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ically varying in value, both of which facts complicate and renderdifficult the attainment of the conditions best suited to the mostefficient working conditions; in other words, they require, first,that for a given inductive effect upon the armature there shouldbe the greatest possible current through the armature or inducedcoils, and, second, that there should always exist between thecurrents in the energizing and the induced circuits a given rela-tion of phase. Hence whatever tends to decrease the self-induc-tion and increase the current in the induced circuits will, otherthings being equal, increase the output and efficiency of the mo-tor, and the same will be true of causes that operate to maintainthe mutual attractive effect between the field magnets and arma-ture at its maximum. Mr. Tesla secures these results by con-necting with the induced circuit or circuits a condenser, in themanner described below, and he also, with this purpose in view,constructs the motor in a special manner.

.Referring to the drawings, Fig. 86, is a view, mainly dia-grammatic, of an alternating current motor, in which the presentprinciple is applied. • Fig. 87 is a central section, in line withthe shaft, of a special form of armature core. Fig. 88 is a simi-lar section of a modification of the same. Fig. 89 is one of thesections of the core detached. Fig. 90 is a diagram showing amodified disposition of the armature or induced circuits.

The general plan of the invention is illustrated in Fig. 86.a a in this figure represent the the frame and field magnets ofan alternating current motor, the poles or projections of whichare wound with coils n and c, forming independent energizingcircuits connected either to the same or to independent sourcesof alternating currents, so that the currents flowing through thecircuits, respectively, will have a difference of phase. Withinthe influence of this field is an armature core d, wound with coilse. In motors of this description heretofore these coils have beenclosed upon themselves, or connected in a closed series; but inthe present case each coil or the connected series of coils termi-nates in the opposite plates of a condenser f. For this purposethe ends of the series of coils are brought out through the shaftto collecting rings «, which are connected to the condenser bycontact brushes h and suitable conductors, the condenser beingindependent of the machine. The armature coils are wound orconnected in such manner that adjacent coils produce oppositepoles.