

of Steel Needle-Points in A 



ir. 





Table III. 





Needle. r. 



n v 



n.,. 



C .... 



0-7X10 3 



0-31 



0-20 



D.... 



! 1-6 „ 



042 



0-36 



E.... 



1 1-88 „ 



0-39 



0-34 



F .... 



I 403 „ 



48 



0-35 



a .... 



1 4-84 .. 



048 



044 



H.... 



B-52 . 



0'50 



0-39 



I .... 



i 7-11 „ 



053 



0-42 



J .... 



I 7-83 „ 



0-49 



0-38 



K.... 



......! 8-71 „ 



0-52 



040 



L .... 



' 10-9 „ 



0-52 



0-46 



M.... 



31-8 ., 



0-61 



0-58 



N.... 



.... 45-7 ., 



0-69 



0-61 



.... 



..;. 58-0 .. 



0-69 



0-56 



X... 



....' 400-0 „ 



1 



[0-80] 



0-72 



301 



The needle marked X was in reality a steel ball used 

 for bicycle-bearings. This was put opposite a tin disk of 

 6 centiin. diameter at a distance of 3" 6 centim. n was calcu- 

 lated from measurements of the difference of potential between 

 ball and plate, as /could not be measured. The values of n 

 fit in well with the rest, (n-^ was calculated in this case from 

 /at 40 and 60 centim. mercury.) 



Now pressure alters the length and closeness of the chains 

 at the same time ; but, for a given field-strength at a point- 

 surface, alteration in curvature gives rise to alteration of 

 chain-length only, the length being less as the point gets 

 sharper. Hence at a sharp point /is more dependent on the 

 length of the chains than at a blunt one; it is in fact nearer 

 its minimum value, and n is consequently less. This, too, is 

 shown very clearly in Table III. 



A pretty illustration of the influence of point curvature on n 

 was accidentally met with in the case of needle C. In getting 

 it into the apparatus for repetition of the curves obtained with 

 it, its point came against the metal box and was flattened 

 slightly to a width of about 3*6 x 10 ~ 3 centim. The values of 

 n x and n 2 obtained from it after this were respectively 0*42 

 and 0'30, instead of 0*31 and 0*2 for the finer point. 



Grotthuss chains, coupled with constant atomic charge, are 

 thus well able to explain most of the phenomena described in 

 this paper. There still remains one which is perhaps the most 

 important of all — the difference in the behaviour of positive 

 and negative discharge. This I hope to discuss in connexion 

 with experiments now in progress, but it may perhaps be well 

 to place on record the results so far obtained. 



