Nikola Tesla - Free-Energy Devices

HIGH FREQUENCY AND HIGH POTENTIAL CURRENTS. 225some experiments, and many timesconvenient for the purposesof adjustment, I cover the secondary with wax, and turn it offin a lathe to a diameter slightly smaller than the inside of theprimary coil. The latter I provide with a handle reaching outof the oil, which serves to shift it in any position along thesecondary.I will now venture to make, in regard to the general manipulationof induction coils, a few observations bearing upon pointswhich have not been fully appreciated in earlier experimentswith such coils, and are even now often overlooked.The secondary of the coil possesses usually such a high selfinductionthat the current through the wire is inappreciable, andmay be so even when the terminals are joined by a conductor ofsmall resistance. If capacity is added to the terminals, the selfinductionis counteracted, and a stronger current is made to flowthrough the secondary, thoughits terminals are insulated fromeach other. To one entirely unacquainted with the properties ofalternating currents nothing will look more puzzling. This featurewas illustrated in the experiment performed at the beginningwith the top plates of wire gauze attached to the terminals andthe rubber plate. When the plates of wire gauze were close together,and a small arc passed between them, the arc prevented astrong current from passing through the secondary, because itdid away with the capacity on the terminals when the rubber;plate was inserted between, the capacity of the condenser formedcounteracted the self-induction of the secondary, a stronger currentpassed now, the coil performed more work, and the dischargewas by far more powerful.The first thing, then, in operating the induction coil is to combinecapacity with the secondary to overcome the self-induction.If the frequencies and potentials are very high, gaseous mattershould be carefully kept away from the charged surfaces. IfLeyden jars are used, they should be immersed in oil, as otherwiseconsiderable dissipation may occur if the jars are greatlystrained. When high frequencies are used, it is of equal importanceto combine a condenser with the primary. One mayuse a condenser connected to the ends of the primary or to theterminals of the alternator, but the latter is not to be recommended,as the machine might be injured. The best way isundoubtedly to use the condenser in series with the primary andwith the alternator, and to adjust its capacity so as to annul the