714 Prof. E. Taylor Jones and Mr. D. E. Roberts on 



The greatest sparking-distance between the two spheres 

 under the circumstances of this experiment was found to be 

 1 centimetre. 









Fig. 4. 







140 

















Volts 



120 





A 







35,000- 





/ 









100 















\ 











/ 







\A 



30.000- 



h- 80 



o 



t> (30 



/ 



\ 





\ 





f\l 









25.000- 



j 













1 



\ 









40 



— J 



\ 





\ 



2^000- 



20 



J 





\/ 



\ 



V / 10.000- 



12 3^ 



»! =230-2, 7i 2 =1444-7, f = 6-75 amp. 



It will be observed that in all the above cases the calculated 

 value of the secondary potential is considerably greater than 

 the observed value, and that the percentage difference 

 increases with the potential. 



Experiments witli no Condenser in the Secondary Circuit. 



If the condenser is removed from the secondary circuit of 

 the smaller induction-coil, one of the oscillations becomes 

 too rapid to be faithfully recorded by the oscillograph. The 

 18-inch spark coil was therefore used for the three following 

 cases, its secondary having much greater self-inductance and 

 capacity. 



In order to work out the expression (1) for these cases it 

 is necessary to know the value of the effective capacity of 

 the secondary coil with greater accuracy than was required 

 in the former cases. After several methods had been tried for 

 the determination of this quantity, the following was finally 



