HIGH FREQUENCY AND HIGH POTENTIAL CURRENTS. 143

with these currents, such an amount of energy can be passedthrough the body with impunity. He then showed by experi-ment the difference between a steady and a rapidly varying forceupon the dielectric. This difference is most strikingly illustratedin the experiment in which a bulb attached to the end of a wirein connection with one of the terminals of the transformer isruptured, although all extraneous bodies are remote from thebulb. He next illustrates how mechanical motions are producedby a varying electrostatic force acting through a gaseous medium.The importance of the action of the air is particularly illustratedby an interesting experiment.

Taking up another class of phenomena, namely, those of dyna-mic electricity, Mr. Tesla produced in a number of experimentsa variety of effects by the employment of only a single wirewith the evident intent of impressing upon his audience the ideathat electric vibration or current can be transmitted with ease,without any return circuit; also how currents so transmitted canbe converted and used for many practical purposes. A numberof experiments are then shown, illustrating the effects of fre-quency, self-induction and capacity; then a number of ways ofoperating motive and other devices by the use of a single lead.A number of novel impedance phenomena are also shown whichcannot fail to arouse interest.

Mr. Tesla next dwelt upon a subject which he thinks of great-importance, that is, electrical resonance, which he explained in apopular way. He expressed his firm conviction that by observ-ing proper conditions, intelligence, and possibly even power, canbe transmitted through the medium or through the earth; andhe considers this problem worthy of serious and immediate con-sideration.

Coming now to the light phenomena in particular, he illustratedtlie four distinct kinds of these phenomena in an original way,which to many must have been a revelation. Mr. Tesla attributesthese light effects to molecular or atomic impacts produced by avarying electrostatic stress in a gaseous medium. He illustratedin a series of novel experiments the effect of the gas surround-ing the conductor and shows bevond a doubt that with high fre-quency and high potential currents, the surrounding gas is ofparamount importance in the heating of the conductor. Heattributes the heating partially to a conduction current and par-tially to bombardment, and demonstrates that in many cases the