Nipher — On the Nature of the Electric Discharge. 15 



really a drawing in of the negative "fluid" from the 

 bodies which are thus "positively electrified." 



Another line of experiment which was begun in 1907 

 consists in passing a discharge from the influence ma- 

 chine around right angles in a fine wire placed in either 

 of the separately grounded lines. The object sought was 

 to determine whether there was any difference in the 

 fogging effect on a photographic film on the two sides of 

 an angle. It was found impossible to simultaneously ex- 

 amine the two sides of the same angle. The arrange- 

 ments shown in Fig. 2 were both employed. The fine wire 



o 



o 



± \J 



r- 



r 



Fig. 2. 



-O 



o 



B 



(No. 32) was bent sharply around thin bamboo splinters. 

 The resistance between the angles and the ground was 

 made as small as was possible, but wet string resistances 

 were placed between the angles and the spark-gaps at the 

 terminals, in order to quiet any oscillations that might 

 possibly be produced. In the earlier work, the photo- 

 graphic plates were placed in hard rubber holders, which 

 rested on a sheet of glass upon which the angles were 

 mounted. The covers and bottoms of these holders had 

 various thicknesses, from one to three-sixteenths of an 

 inch. It was found that under these conditions, when 

 proper adjustments had been secured, the greatest fog- 

 ging effect was produced on the plate towards which the 

 negative discharge passed downwards around the angle 

 and then across the plate. In the negative line arrange- 

 ment A of Fig. 2 was used. In the positive line arrange- 

 ment B was used. In this line the negative discharge 

 passed from the ground to the machine. The effect was 

 greatest at the angle nearest the ground, in both cases. 

 The wires were raised above the plates to such a height 



