248 TABLES 255, 256. 



DIELECTRIC STRENGTH. 



TABLE 255. Steady Potential Difference In Volts required to produce a Spark In Air with Ball Electrodes. 



Based on the results of Bailie, Bichat-Blondot, Freyburg, Liebig, Macfarlane, Orgler, Paschen, Quincke, de la Rue, 

 Wolff. For spark lengths from i to 200 wave-lengths of sodium light, see Earhart, Phys. Rev. 15, p. 163; Hobbs, 

 Phil. Mag. 10, p. 607, 1905. 



TABLE 266. Alternating Current Potentials required to produce a Spark In Air with various Ball Elec- 

 trodes. 



The potentials given are the maxima of the alternating waves used. Frequency, 33 cycles per 



second. 



Based upon the results of Kawalski, Phil. Mag. 18, 1909. 



SMITHSONIAN TABLES. 



