Spottiswoode on Stratification in Electrical Discharges. 243 



nexion with the secondary wire of the induction-coil, except on 

 making and breaking the connexion with the battery. At other 

 times there was evidently no fluctuation in the continuous dis- 

 charge, no periodic increase or diminution of flow, and conse- 

 quently no induced current in the secondary wire s s' of L the in- 

 duction-coil. 



In the second experiment wires were also led from the terminals 

 of the battery (all other things remaining as before) to the coil- 

 accumulator as in fig. 4 ; then immediately the discharge in V 

 became stratified and the secondary vacuum-tube V 2 lighted up, 

 clearly showing that under these circumstances a fluctuation in the 

 discharge really occurs on the appearance of stratification. 



The brilliancy of the discharge in V 2 (the induced current passes 

 through complicated vacuum-tubes through which the primary 

 current cannot pass) depends greatly on the quality and quantity 

 of the discharge in the primary vacuum-tube V. Under some cir- 

 cumstances the secondary discharge is extremely feeble, and the 

 illumination in V 2 barely visible ; under others it is very brilliant. 



Preparations are being made to render evident induced currents 

 in the secondary wire of the coil too feeble to produce any illumina- 

 tion. Pending the further development of our investigation, we 

 have ventured to give an account of our progress in elucidating 

 some points in the theory of the vacuum-discharge, without any 

 wish to ascribe to our results more weight than they deserve. 



Fig. 4. 



