Nikola Tesla - Free-Energy Devices

218 INVENTIONS OF NIKOLA TE8LA.cover novel methods of producing light by the agitation of atoms,or molecules, of a gas,we need not limit our research to thevacuum tube, but may look forward quite seriously to the possibilityof obtaining the light effects without the use of any vesselwhatever, with air at ordinary pressure.Such discharges of very high frequency, which render luminousthe air at ordinary pressures, we have probably occasion often towitness in Nature. I have no doubt that if, as many believe, theaurora borealis isproduced by suddencosmic disturbances, suchas eruptions at the sun's surface, which set the electrostatic chargeof the earth in an extremely rapid vibration, the red glow observedis not confined to the upper rarefied strata of the air, butthe discharge traverses, by reason of its very high frequency,also the dense atmosphere in the form of a glow, such as we ordinarilyproduce in a slightly exhausted tube. If the frequencywere very low, or even more so, if the charge were not at allvibrating, the dense air would break down as in a lightning discharge.Indications of such breaking down of the lower densestrata of the air have been repeatedly observed at the occurenceof this marvelous phenomenon but if it does; occur, it can onlybe attributed to the fundamental disturbances, which are few innumber, for the vibration produced by them would be far tooIt is the original and irregularimpulses which affect the instruments ; the superimposed vibrationsprobably pass unnoticed.When an ordinary low frequency discharge is passed throughmoderately rarefied air, the air assumes a purplish hue. If bysome means or other we increase the intensity of the molecular,rapid to allow a disruptive break.or atomic, vibration, the gas changes to a white color.A similarchange occurs at ordinary pressures with electric impulses of veryhigh frequency. If the molecules of the air around a wire aremoderately agitated, the brush formed is reddish or violet if;the vibration is rendered sufficiently intense, the streams becomewhite. We may accomplish this in various ways. In the experimentbefore shown with the two wires across the room, I haveendeavored to secure the result by pushing to a high value boththe frequency and potential ;in the experiment with the thinwires glued on the rubber plate I have concentrated the actionupon a very small surface inother words, I have worked witha great electric density.A most curious form of discharge is observed with such a coil