58 



Prof. D. ^ . Mallik and Mr. A. B. Das on Electric 



and similarly plotted in curve IV., fig. 19, we come to the 

 conclusion that the voltage of the secondary of an induction 

 coil, under the conditions of these experiments, is fairly 

 accurately measured by the distance of the minimum spark- 

 gap, across which it forces a discharge and is practically 

 proportional to this distance. 



Fig. 19. Curve IV. 



00 









































/ 























































































































/ 









80 







































































































































































60 



















































































50 



























































V 

























40 



















































































30 

















































































20 















































/ 





































10 





/ 































. 









* 



J 















\ 





















1 



•3 -4- -5 -6 -7 -8 -9' 



Spark lengtfi in cm., with spheres 3 cm. diam r —■ > 



[Data from Baillie's results— J. J. Thomson's ' Conduction of Electricity 

 through Gases/ 2nd ed. page 461.] 



It follows also that the potential difference between the 

 electrodes of the discharge-tube is measurable in terms of 

 the minimum spark-gap with which it is parallel. In this 

 way, the potential difference between the electrodes of the 

 discharge-tube at different pressures of the contained air 

 has been determined. 



22. Fig. 20, curve V. represents changes in the P.D. 

 with pressure, when the disk is the cathode, the spark- 

 length of the induction-coil in this case being 13*4 mm. in 

 atmospheric air. 



