Nikola Tesla - Free-Energy Devices

SIGH FREQUENCY AND HIGH POTENTIAL CURRENTS. 155the several types of these machines which have been constructedby me, I have found that the type illustrated in Fig. 97 causedme the least trouble in construction, as well as in maintenance,and on the whole, it has been a good experimental machine.In operating an induction coil with very rapidly alternatingcurrents, among the first luminous phenomena noticed are naturallythose presented by the high-tension discharge.As the numberof alternations per second is increased, or as the numberbeing high the current through the primary is varied, the dischargegradually changes in appearance. It would be difficult todescribe the minor changes which occur, and the conditions whichiFIG. 99.bring them about, but one may note five distinct forms of thedischarge.First, one may observe a weak, sensitive discharge in the formof a thin, feeble-colored thread. (Fig. lOOa.)It always occurswhen, the number of alternations per second being high, the currentthrough the primary is very small. In spite of the excessivelysmall current, the rate of change is great, and the differenceof potential at the terminals of the secondaryis thereforeconsiderable, so that the arc is established at great distances ; butthe quantity of " electricity " set in motion is insignificant, barelysufficient to maintain a thin, threadlike arc. It is excessivelysensitive and may be made so to such a degree that the mere actof breathing near the coil will affect it,and unless it is perfectly