Nikola Tesla - Free-Energy Devices

HIGH FRJSQVKNCy AND HIGH POTENTIAL CURRENTS. 125whicli tlie impedance f a coil was not affected by the presenceof a core consisting of a bundle of very thin well annealed andvarnished iron wires.Experiments with a telephone, a conductor in a strong magneticfield, or with a condenser or arc, seem to afford certainproof that sounds far above the usually accepted limit of hearingwould be perceived ifproduced with sufficient power. The arcproduced by these currents possesses several interesting features.Usually it emits a note the pitch of which corresponds to twicethe frequency of the current, but if the frequency be sufficientlyhigh it becomes noiseless, the limit of audition being determinedprincipally by the linear dimensions of the arc. A curious featureof the arc is its persistency, which is due partly to the inabilityof the gaseous column to cool and increase considerablyin resistance, as is the case with low frequencies, and partly tothe tendency of such a high frequency machine to maintain aconstant current.In connection with these machines the condenser affords a particularlyinteresting study. Striking effects are produced byproper adjustments of capacity and self-induction. It is easy toraise the electromotive force of the machine to many times theoriginal value by simply adjusting the capacity of a condenserconnected in the induced circuit. If the condenser be at somedistance from the machine, the difference of potential on theterminals of the latter may be only a small fraction of that onthe condenser.But the most interesting experiences are gained when the tensionof the currents from the machine is raised by means of aninduction coil. In consequence of the enormous rate of changeobtainable in the primary current, much higher potential differencesare obtained than with coils operated in the usual ways,and, owing to the high frequency, the secondary discharge possessesmany striking peculiarities. Both the electrodes behavegenerally alike, though it appears from some observations thatone current impulse preponderates over the other, as beforementioned.The physiological effects of the high tension discharge arefound to be so small that the shock of the coil can be supportedwithout any inconvenience, except perhaps a small burn producedby the discharge upon approaching the hand to one of the terminals.The decidedly smaller physiological effects of these cur-