Surface of large Curvature. 179 



A typical series of observations is given below : the lengths 

 of the discharge wires were each 10 cm ; the radii of the cylin- 

 ders were 5*0 cm , 3'2 cm and l*5 cm respectively ; that of the dis- 

 charge wire was 0*0034 cm . 



Table III. 



Applied Current. Ratios, 



potentials. h I 2 I3 l 2 I 3 



in for for for y~ j- 



volts. r = 5-0. r = 3-2. r=l'5. * 2 



3500 4-0 16*0 152' 4-0 9*5 



3800 24- 200* 8*3 



4000 9-0 36' 290* 4-0 8*0 



4500 19* 74- 480* 3'9 6'5 



5000 31- 118' 3'8 



5500 55* 189" 3*4 



Mean values, 3'82 8*1 



The ratios r^/rf and ff/rj have the values 3*8 and 9*7, 

 respectively. The variations obtained were usually within the 

 limit of those shown in this series. 



7. In resume, then, it has been found that the current dis- 

 charging from* a fine wire to a concentric surrounding cylinder 

 is given by the equation, — 



where, 



I = the discharge current 



V= the potential difference between wire and cylinder 



L = length of the discharge wire 



r = radius of the cylinder 



b = the minimum potential necessary to produce a meas- 

 urable discharge, 

 and, a = a constant depending upon the size of the wire, t the 

 discharging gas, and the sign of the discharge. 



Physical Laboratory, 

 University of Nebraska, May, 1901. 



