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INTENTIONS OF NIKOLA TESLA.

teresting experiments illustrative of the behavior of the air be-tween charged surfaces, the luminous streams formed by thecharged molecules appearing even when great thicknesses of thebest insulators are interposed between the charged surfaces.These luminous streams afford in themselves a very interestingstudy for the experimenter. With these rapidly alternating cur-rents they become far more powerful and produce beautiful lighteffects when they issue from a wire, pinwheel or other object at-tached to a terminal of the coil; and it is interesting to note thatthey issue from a ball almost as freely as from a point, when thefrequency is very high.

From these experiments we also obtain a better idea of theimportance of taking into account the capacity and self-inductionin the apparatus employed and the possibilities offered by theuse of condensers in conjunction with alternate currents, the em-ployment, of currents of high frequency, among other things,making it possible to reduce the condenser to practicable dimen-sions. Another point of interest and practical bearing is thefact, proved by Mr. Tesla, that for alternate currents, especiallythose of high frequency, insulators are required possessing asmall specific inductive capacity, which at the same time have ahigh insulating power.

Mr. Tesla also makes interesting and valuable suggestion in re-gard to the economical utilization of iron in machines and trans-formers. lie shows how, by maintaining by continuous magnet-ization a flow of lines through the iron, the latter may be keptnear its maximum permeability and a higher output and economymay he secured in such apparatus. This principle may prove ofconsiderable commercial importance in the development of alter-nating systems. Mr. Tesla’s suggestion that the same result canbe secured by heating the iron by hysteresis and eddy currents,and increasing the permeability in this manner, while it may ap-pear less practical, nevertheless opens another direction for inves-tigation and improvement.

The demonstration of the fact that with alternating currentsof high frequency, sufficient energy may he transmitted underpracticable conditions through the glass of an incandescent lampby electrostatic or electromagnetic induction may lead to a de-parture in the construction of such devices. Another importantexperimental result achieved is the operation of lamps, and evenmotors, with the discharges of condensers, this method affording