Nikola Tesla - Free-Energy Devices

CHAPTEK XXIX.TESLA ALTERNATING CURRENT GENERATORS FOR HIGH FRE-QUENCY, INDETAIL.It lias become a common practice to operate arc lamps by alternatingor pulsating, as distinguished from continuous, currents ;but an objection which has been raised to such systems exists inthe fact that the arcs emit a pronounced sound, varying with therate of the alternations or pulsations of current. This noise isdue to the rapidly alternating heating and cooling, and consequentexpansion and contraction, of the gaseous matter formingthearc, which corresponds with the periods or impulses of thecurrent. Another disadvantageous feature is found in the difficultyof maintaining an alternating current arc in consequence ofthe periodical increase in resistance corresponding to the periodicalworking of the current. This feature entails a further disadvantage,namely, that small arcs are impracticable.Theoretical considerations have led Mr. Tesla to the beliefthat these disadvantageous features could be obviated by employingcurrents of a sufficiently high number of alternations, and hisanticipations have been confirmed in practice. These rapidlyalternating currents render it possible to maintain small arcswhich, besides, possess the advantages of silence and persistency.The latter quality is due to the necessarily rapid alternation^ inconsequence of which the arc has no time to cool, and is alwaysmaintained at a high temperature and low resistance.At the outset of his experiments Mr. Tesla encountered greatdifficulties in the construction of high frequency machines. Agenerator of this kind is described here, which, though constructedquite some time ago,is well worthy of a detailed description.Itmay be mentioned, in passing, that dynamos ofthis type have been used by Mr. Tesla in his lighting researchesand experiments with currents of high potential and high frequency,and reference to them will be found in his lectureselsewhere printed in this volume. 11. See pages 153-4 5.