68 



Mr. J. H. Pepper on some Experiments [June 17, 



inches. 



10 one-half f + 18*00 



„ reduced ^ 17*25 



t 



20 full condenser 21*25 



,, reduced one-half + 22 



30 full condenser 23*5 



„ reduced one-half. . + 23*5 



40 full condenser 25*0 



one-half + 25*0 



50 full condenser 28 



one-half + 28 



Experiments were now tried to ascertain whether any increase in the 

 length of the spark could be obtained by arranging the battery and the 

 primary coil for quantity. 



inches. 



5 + 5 cells, length of spark 14*5 



10 + 10 cells, „ 18 0 



20 + 20 cells, „ 21*75 



25 + 25 cells, „ 23*75 



15 + 15+15 cells, „ 20*00 



It is evident that no material advantage was obtained by the above 

 arrangement except in the first experiment ; and even where three groups 

 were connected, as in the last experiment, a decrease in the length of the 

 spark is observed when compared with the 45 or 50 cells arranged for 

 intensity, the difference being as 20 to 28. 



The spark obtained from the large coil presents some novel and curious 

 features. It is thick and flame-like in its appearance, and therefore it will 

 be alluded to as the " flaming spark." 



When the discharging-point and circular plate are brought within 6 or 

 7 inches of each other, the flaming nature of the spark becomes still more 

 apparent. 



Two light yellow flames curving upwards appear to connect the opposite 

 poles. If a blast of air from powerful bellows is directed against the 

 flaming spark, the flaming portion can be blown away and increased in 

 area ; and thin wiry sparks are now seen darting through it, sometimes in 

 one continuous stream, at another time divided into three or more sparks, 

 all following the direction in which the flame is blown. 



The heat of this is very great, and, if passed through asbestos (sup- 

 ported on an insulating pillar), quickly causes the latter to become red-hot. 



When powdered charcoal is shaken from a pepper-box int*> the flaming 



