TABLES 257, 258. 249 



DIELECTRIC STRENGTH. 



TABLE 257. 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 

 id "dull point" electrodes, and the results with steady potential found ' " 



and 



ler, Ann. d. Phys. 29, 1909. 



in the recent very careful work of C. Miil- 



EJ 



22 cm. 



The specially constructed elec- 

 trodes for the columns headed 

 " cup electrodes " had the form of 

 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- 

 linear relation between the 

 lengths and the voltage 

 ut the range studied. 



TABLE 258. Effect of 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-Bornstein- 

 Meyerhoffer). 



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

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



SMITHSONIAN TABLES. 



