Nipher — On the Nature of the Electric Discharge. 63 



towards the grounded terminal in a more strongly- 

 marked way. It certainly might be expected that some 

 such effect might exist in case of a disruptive discharge. 



Fig. B of Plate XXIII was exposed in the positive line 

 in precisely the same way that former plates were ex- 

 posed in the negative line. Here the negative discharge 

 comes from the ground. The ionization is produced at 

 the positive pin-head terminal, which is connected with 

 the positive terminal of the machine. 



In Fig. C of Plate XXIII the pin-head terminals were 

 connected with the + and — terminals of the machine. 

 The spark-gaps at the machine were not more than 3 or 

 4 mm. A single spark was passed through these gaps. This 

 figure shows what is clearly shown in other plates, how 

 insignificant is the ionizing effect at the negative termi- 

 nal, as compared with that which produces the negative 

 inflow at the positive terminal. In this plate these ioni- 

 zation effects are due to the exhaust effects at the posi- 

 tive terminal and to the presence of the negative termi- 

 nal, which produces such effects at the opposite terminal, 

 even when it is grounded. The effect is to be finally 

 traced to the forced rotation of the glass plates of the 

 machine in the presence of the inductor cards on the sta- 

 tionary plates 



In this figure it will be observed that one of the stream 

 lines which proceeds to the positive terminal curves 

 around the small black area at the negative terminal. Its 

 source is on the opposite side of the negative terminal 

 from the positive terminal. Its curved form is due to the 

 negative outflow from the negative terminal. 



In this figure as well as in Fig. A of Plate XXI the 

 discharge lines have a form which suggests lines of force 

 from static charges of opposite sign. It is, however, to 

 be observed that the conditions in these fields of force 

 are dynamic in character. There is an outflow of gaseous 

 molecules from both terminals, as will be explained later. 

 The meeting and mingling of these oppositely directed 

 "electric winds," produced the disturbed condition that 

 is to be observed between the terminals and just outside 



