356 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



TABLE I. 



Shift of spark lines \\ 3900 and 3913 to red from position of arc lines. 



Metal used- Titanium Carbide, 85 per cent Ti, 15 per cent C. 



Arc vertical: length 3mm. Spark horizontal: length 9 mm. 



End of spark image always used. 



Capacity of condenser : 0.0226 microfarads. 



Times of exposures : arc 5 + 5 seconds, spark 75 seconds. 



