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INTENTIONS OF NIKOLA TESLA.

100-volt and the latter a 50-volt are placed in certain positions asindicated, the 100-volt lamp being below the 50-volt lamp. Whenthe arc is playing at d d and the sudden discharges are passedthrough the bars b b,, the 50-volt lamp will, as a rule, burn brightly,or at least this result is easily secured, while the 100-volt lampwill burn very low or remain quite dark, Fig. 183J. Now thebars b Bi may be joined at the top by a thick cross bar b 2 and itis quite easy to maintain the 100-volt lamp at full candle-powerwhile the 50-volt lamp remains dark, Fig. 183c. These results,as I have pointed out previously, should not be considered to bedue exactly to frequency but rather to the time rate of changewhich may be great, even with low frequencies. A great manyother results of the same kind, equally interesting, especially tothose who are only used to manipulate steady currents, may beobtained and they afford precious clues in investigating the na-ture of electric currents.

In the preceding experiments I have already had occasion toshow some light phenomena and it would now be proper to studythese in particular; but to make this investigation more com-plete I think it necessary to make first a few* remarks on thesubject of electrical resonance which has to be always observedin carrying out these experiments.

ON ELECTRICAL RESONANCE.

The effects of resonance are being more and more noted by engi-neers and are becoming of great importance in the practical opera-tion of apparatus of all kinds with alternating currents. A fewgeneral remarks may therefore be made concerning these effects.It is clear, that if we succeed in employing the effects of resonancepractically in the operation of electric devices the return wire will,as a matter of course, become unnecessary, for the electric vibra-tion may be conveyed with one wire just as well as, and sometimeseven better than, with two. The question first to answer is, then,whether pure resonance effects are producible. Theory and ex-periment both show that such is impossible in Nature, for as theoscillation becomes more and more vigorous, the losses in the vi~brating bodies and environing media rapidly increase and necessa-rily check the vibration which otherwise would go on increasingforever. It is a fortunate circumstance that pure resonance isnot producible, for if it were there is no telling what dangersmight not lie in wait for the innocent experimenter. But to a