220 J. A. POLLOCK, E. M. WELLISCH AND A. B. B. RANCLAUD. 
of the carbons, vertically from the point of the negative to 
a horizontal line passing through the edge of the crater, 
the values obtained being reduced according to the magni- 
fication of the image. 
3. Relighting with carbons in normal positions when 
potentials are reversed.—When the connections from the 
battery are reversed during the interval between the open- 
ing and closing of the circuit, so that at the remake of the 
circuit the still existing crater becomes negative to the 
previous cathode, the crater being on the upper carbon, 
the phenomena are simpler than in other cases and will 
therefore be the first described. 
Ric. 
S 
& 
@ 
oO 
Previous current \!O amperes. 
Potential difference between Carbons at make of circuit in Volts. 
3 4 
0 4 2 5 
Interval between break and make of circuit in Seconds. 
Relation for critical relighting ; carbons in normal position, 
potentials reversed. 
