440 



Tables 51 5 and 51 6 

 DIELECTRIC STRENGTH 



TABLE 515. — Potential Necessary to produce a Spark In Air between more widely Separated Electrodes 



This table for longer spark lengths contains the results of Voege, Ann. der Phys. 14, 1904, using alternating current 

 and "dull point" electrodes, and the results with steady potential found in the recent very careful work of C. MiH 

 ler, Ann. d. .Phys. 28, p. 585, 1909. 



The specially constructed elec- 

 trodes for the columns headed 

 " cup electrodes " had the form of 

 _4; /: a projecting knob 3 cm in diame- 

 ter and having a height of 4.5 mm 

 and 1.5 mm respectively, attached 

 to the plane face of the electrodes. 

 These electrodes give a very satis- 

 factory linear relation between the 

 spark lengths and the voltage 

 throughout the range studied. 



TABLE 516.— Effect ol the Pressure of the Gas on the Dielectric Strength 



Voltages are given for different spark lengths /. 



This table is based upon the results of Orgler, 1899. See this paper for work on other gases (or Landolt-BSrnstein- 



For long spark lengths in various gases see Voege, Electrotechn. Z. 28, 1907. For dielectric strength of air and C0 2 

 in cylindrical air condensers, see Wien, Ann. d. Phys. 29, p. 679, 1909. 



Smithsonian Tables. 



