372 



Popular Science Monthly 



Making a Stage Ocean with Green Silk 

 and an Electric Fan 



ATTEMPTS made to devise apparatus 

 L by which the effect of a heavy sea can 

 be obtained on the stage without actually 

 employing. water have been somewhat un- 

 successful. Ordinarily a large canvas is 

 employed, painted to represent waves and 

 moved by machine or by hand beneath the 

 canvas, Stereopticon pictures and colored 

 lights have 

 been utilized 

 to make the 

 effects more 

 reahstic. All 

 these at- 

 tempts have 

 not only been 

 expensive 

 and cumber- 

 some but 

 have proved 

 unsatisfac- 

 tory. They 

 lacked real- 

 ism. 



Ida May 

 Fuller, of 

 New York 



Festoons of light-weight silk, sea-green in color, are supported 

 by wire netting and waved by the air currents from the fan 



city, has obtained satisfactory results on 

 the stage by means of an openwork support, 

 preferably of light, white netting, to which 

 is attached in festoons on the front side a 

 fabric such as a fine translucent silk, which 

 reflects light and which is of such texture as 

 to be easily waved back and forth by an 

 electric fan or by hand. 



Water-green colored silk produces a sat- 

 isfactory illusion, without any external 

 lighting effects, regardless of whether the 

 motion of the waves is made by stage hands 

 moving the support or whether an electric 

 fan is used. When it is desired to show 

 figures or objects beneath the water the 

 figures are placed beneath the projecting 

 light and behind the support. 



attached has been employed to generate 

 the electricity. William H. Chapman, of 

 Portland, Maine, applies the contact prin- 

 ciple of the iron pulley and belt instead 

 of the principle of friction in static gene- 

 rators. 



In his machine the usual friction pads 

 give place to a trough of mercury, analogous 

 to the iron pulley. Not only is an unpre- 

 cedented mechanical efficiency obtained but 



from an elec- 

 trical stand- 

 point the 

 high p o - 

 tential effects 

 are of an 

 order not 

 heretofore 

 attainable 

 with friction 

 apparatus. 



A glass plate 

 eight inches 

 in diameter, 

 making eighty 

 complete rev- 

 olutions a 

 minute and 

 dipping into 





a mercury trough to a depth of one and one 

 half inches, without induction plates, will 

 develop a potential of 9,000 volts on comb 

 points, arranged to collect the charge at 

 the top of the plate. The application of 

 induction plates close to the revolving plate, 

 at the point where it leaves the mercury, 

 raises the potential to 13,000 volts or more 

 on the comb points and gives sparks three- 

 quarter inch long. This is still further 

 increased by covering the induction plates 

 with k thin sheet of rubber or glass. 



ROUNDED TO PREVE.NT 

 BRUSH DISCHARGES 



CHARGE COLLECTING 

 TEETM 



GLASS DISC 



A Frictionless Contact Generator 

 of Static Electricity 



WHEN two dissimilar substances are 

 pressed together and then separated, 

 one acquires a positive charge and the other 

 a negative charge. A leather belt running 

 on an iron pulley is an illustration of this. 

 The belt) acquires a negative charge at the 

 point of separation from the pulley and the 

 pulley a positive charge. 



Hitherto, with static generators, a mov- 

 ing plate of glass with frictional rubbers 



TROUGH 



DUCTION PLATE 

 FOR KEEPING DISC 

 DISCHARGE LOW 

 NEAR MERCURY 

 AND DISC CONTACT 

 POINT 



In this machine a trough of mercury is 

 employed to generate electricity by contact 



