223 
RELIGHTING OF THE CARBON ARC. 
Fig. 4. 
Ss 
wo 
S 
a Previous current 10 eee 
Interval enon Arent ee, make of Alor in ence 
oO 
[=] 
Arc length 3mm. 
See ditference between carbons at make of circu/t jn Volts. 
Relation for critical relighting as affected by changes in the rela- 
tive positions of the carbons. 
In figure 4 are shown the relations between the minimum 
potential difference for relighting and the time interval of 
interruption of the circuit for the four cases mentioned, 
the current having been 10 amperes when the connections 
were broken and the arc length 1°3 millimetres. The 
diagrams of the carbons drawn beside each curve indicate 
by their shape the relative positions of the electrodes before 
the circuit was opened, while the signs of the potentials, 
on the reclosing of the circuit, are shown by the usual 
