POLAR EFFECTS UNDER STRONG CURRENTS 255 



when the exciting current applied reached the value of 3*5 

 micro-amperes the characteristic effect of Type I. — namely, 

 excitation at make of kathode Km — made its appearance. 

 When the current was still further raised to 5*6 micro- 

 amperes, the excitatory effect was of Type II. — namely, 

 Km Ab, that is to say, excitation at the make of kathode 

 and break of anode. In these two cases we have Types I. 

 and II., with which we are already familiar. 



Polar Reaction Type III., Km Am Ab. 



When the progressively increasing current had reached 

 a value of 6-3 micro-amperes, however, a new and unexpected 



Fig. 125. — Effect of increasing intensity of current in trans- 

 forming response Km Ab of Type II. to response Km Am 

 Ab of Type III. 



type of reaction made its appearance. With the bi-polar 

 connections it was found that while one leaf, the kathode, 

 underwent an excitatory fall, the other, or anode, also 

 showed a simultaneous fall at make. After the re-erection of 

 the leaves the current was broken, and now the anodic leaf 

 showed excitation once more, whereas the kathodic exhibited 

 no excitation whatever. In this new type of effect, then, 

 we have excitation both at anode and kathode at make and 



