Popular Science Monthly 



249 



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 



