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INVENTIONS ON NIKOLA TESLA.

plan is to charge condensers, from a direct or alternate-currentsource, preferably of liigli-tension, and to discharge themdisruptively while observing well-known conditions neces-sary to maintain the oscillations of the current. In view of thegeneral interest taken in high-frequency currents and effects pro-ducible by them, it seems to me advisable to dwell at some lengthupon this method of conversion. In order to give you a clearidea of the action, I will suppose that a continuous-current gen-erator is employed, which is often very convenient. It is desirablethat the generator should possess such high tension as to be ableto break through a small air space. If this is not the case, thenauxiliary means have to be resorted to, some of which will be in-dicated subsequently. When the condensers are charged to acertain potential, the air, or insulating space, gives way and a dis-ruptive discharge occurs. There is then a sudden rush of currentand generally a large portion of accumulated electrical energyspends itself. The condensers are thereupon quickly charged andthe same process is repeated in more or less rapid succession.To produce such sudden rushes of current it is necessary to ob-serve certain conditions. If the rate at which the condensers aredischarged is the same as that at which they are charged, then,clearly, in the assumed case the condensers do not come intoplay. If the rate of discharge be smaller than the rate of charg-ing, then, again, the condensers cannot play an important part.But if, on the contrary, the rate of discharging is greater thanthat of charging, then a succession of rushes of current is ob-tained. It is evident that, if the rate at which the energy isdissipated by the discharge is very much greater than the rate.ofsupply to the condensers, the sudden rushes will be compara-tively few, with long-time intervals between. This always occurswhen a condenser of considerable capacity is charged by meansof a comparatively small machine. If the rates of supply anddissipation are not widely different, then the rushes of currentwill be in quicker succession, and this the more, the more nearlyequal both the rates are, until limitations incident to each caseand depending upon a number of causes are reached. Thus weare able to obtain from a continuous-current generator as rapid asuccession of discharges as we like. Of course, the higher thetension of the generator, the smaller need be the capacity of thecondensers, and for this reason, principally, it is of advantage toemploy a generator of very high tension. Besides, such a gener-ator permits the attaining of greater rates of vibration.