Nikola Tesla - Free-Energy Devices

362 INVENTIONS OF NIKOLA TESLA.way, for then the safety is absolute, unaffected by any possiblecombination of circumstances which might render even alow-potentialappliance dangerous to life and property. But the practicalconditions require not only the judicious determination of thedimensions of the apparatus ; they likewise necessitate the employmentof energy of the proper kind. It is easy, for instance,to construct a transformer capable of giving, when operated froman ordinary alternate current machine of low tension, say 50,000volts, which might be required to light a highly exhausted phosphorescenttube, so that, in spite of the high potential, it isperfectly safe, the shock from it producing no inconvenience.Still such a transformer would be expensive, and in itself inefficient;and, besides, what energy was obtained from it would notbe economically used for the production of light. The economydemands the employment of energy in the form of extremely rapidvibrations. The problem of producing light has been likened tothat of maintaining a certain high-pitcli note by means of a bell.It should be said a barely audible note ;and even these wordsxvould not express it, so wonderful is the sensitiveness of the eye.We may deliver powerful blows at long intervals, waste a gooddeal of energy, and still not get what we want ;or we may keepup the note by delivering frequent taps, and get nearer to theobject sought by the expenditure of much less energy. In theproduction of light, as far as the illuminating device is concerned,there can be only one rule that is, to use as high frequencies ascan be obtained ;but the means for the production and conveyanceof impulses of such character impose, at present at least,great limitations. Once it is decided to use very high frequencies,the return wire becomes unnecessary, and all the appliancesare simplified. By the use of obvious means the same result isobtained as though the return wire were used. It is sufficient forthis purpose to bring in contact with the bulb, or merely in thevicinity of the same, an insulated body of some surface. Thesurface need, of course, be the smaller, the higher the frequencyand potential used, and necessarily, also, the higher the economyof the lamp or other device.This plan of working has been resorted to on several occasionsthis evening. So, for instance, when the incandescence of abutton was produced by grasping the bulb with the hand, thebody of the experimenter merely served to intensify the action.The bulb used was similar to that illustrated in Fig. 148, and