::.-,.; 



PROCEEDINGS OF THK AMERICAN ACADEMY. 



TABLE I. 



Shift of spark lines aa.T.KX) ami 3918 to red from position of arc lines. 

 Metal need Titanium I ferbide, 86 per cent Ti, 15 per cent C. 

 Arc vt-riieal : length 3 mm. Spark horizontal : length 'J mm. 



Kinl of spark image always used. 



Capacity of condenser : 0.0220 microfarads. 



Timet "f exposures: arc 5 + 6 seconds, spark 75 seconds. 





