Page:Popular Science Monthly Volume 89.djvu/262

 Toying with HighTension Currents

���At left, Prof. Thordarson and his helper and operat- ing expert, Mr. Lindstrom

��Below, using an umbrella to ex- periment with a three to six-inch spark from the safety-screen

��ELECTRICAL science has brought forth so many startling discoveries in the last decade or two that even the average person is rather proof against being astonished at anything. Ahnost incredible accomplishnients of an inven- tor's years of unremitting labors are often dismissed with the faint praise that electricity is only in its infancy. Like almost all other things, however, there are exhibitions of electric force that tickle the public fancy without con\eying au},^ idea of commercial worth. A good example of this is seen in the theatrical displays with high-frequency currents, the beholders little realizing that they arc interesting applications of the same power employed in wireless telegraph transmission.

A remarkable electrical construction which has excited great interest in both the curious spectator and the far-seeing engineer is the 1,000 kilowatt, 1,000,000- volt, 60-cycle transformer, constructed by the well-known electrical instrument maker, Mr. C. H. Thordarson n{ Chicago. Requiring two years' time in construction, costing $36,000 and entail- ing no end of thought and ingenuity, it was primarily made to demonstrate

���certain theories on transformer con- struction and to investigate the behavior of electric conductors when charged with extremely high \-oltagcs.

Electric currents, when traveling at very high frequency, pass almost entirely u[ion the surface of the conductor. The resistance of such a circuit is therefore so high that unless a high voltage is operating no current at all will flow. Such conditions are met in stage apparatus. Ordinarily the operator can handle the conductors with imiiunit\', the current mereh- passing through his outer skin or perhaps entirely in his clothing. The alternations may readily be a million per second or half |th,it number of "cycles" per second. In the case of ordinary electric light and power circuits the most common frequency is 60 cycles per second, some, however, being as low as 25. In such cases the current flows quite like the direct sort, uniformly through the section of the conductor, whether it be wire or person, and a \oUage as low as 1,000 is likely to be fatal. It is realized, therefore, that in the new Thordarson apparatus there is found for the first time the combina- tion of the high voltage with ordinary

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