Page:Popular Science Monthly Volume 89.djvu/263

 Popular Science Monthly

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��commercial frequencies. Some of the larsjc manufacturing companies have, in recent years, constructed testing transformers for this same sort of circuit, but of only about half the voltage. Only those who have worked with very high voltages can realize the difficulties attending the construction and maintenance of such a special piece of apparatus.

While no one is as yet fully aware of the possibilities of this high power transformer, its electro-static efTects are the most marvelous ever exhibited. Strangely enough, the spectators can actually toy with the powerful charges. Crowds of people at a time could walk through an "electrified" area 50 ft. square and 30 ft. in height, yet with no opportunity for dangerous contact. The general arrangements at the Pan- ama-Pacific Exhibition for a demon- stration were made in a building with convas end containing the trans- former and its controlling accessories, while under the large wire screen suspended by ropes from four electric light poles the visitors could pass and experience the peculiar and vivid sensations of high-voltage charges. Those wearing hat-pins, hair-pins, metal buttons, or carrying metal- handled canes or umbrellas, or even metal-bound purses with their coins, etc., were mysteriously "tickled" and provoked to amusing exclamations of surprise or fright. By holding the hat aloft one could draw sparks from the hat-band ; by holding grounded metal conductors at arm's length 12- in. sparks could easily be drawn from the insulated rope safety-screen sus- pended 10 ft. below the charged screen, each discharge being accom- panied by a diminutive thunder- clap. By merely standing on a box or some other insulating material and raising the hand, sparks three to six inches in length could readily be drawn and then passed along to persons standing on the ground. V'acuum tubes and incandescent lamp bulbs brought beneath the screen were continuously illuminated with the blue glow peculiar to such influence.

On dark nights the entire aerial

��system was a mass of soft glowing "corona," the needle-points of discharge, or places of great concentration of electric spray, sizzling witii the wonder- ful wizardry of electrostatics. On some occasions a corona a foot in diameter was observed surrounding some of the metal conductors. When a grounded water-jet spouted upward against a metal disk suspended from the charged screen the resulting luminous display of electric pyrotechnics was awe-inspiring; the length of the luminous discharges measured over 20 ft., while miniature thunderclaps reverberated to surprising distances. Some of these highly enter- taining and amusing "stunts" are shown in several of the reproductions accom- panying this article.

���This is not a mop, which Prof. Thordarson is holding. Sparks are leaping to the top of a pole in his hand. From the safety-screen high- voltage charges and thunder-claps are coming

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