354 TABLES 428. 429. 



DIELECTRIC STRENGTH. 



TABLE 428. 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 

 it" electrodes, and the results with steady potential found in the recent very careful work of C. Miit- 



and "dull point 



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



The specially constructed elec- 

 trodes lor 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- 

 ?en the 

 voltage 

 iroughout the range studied. 



<3cm.> V ihese electrodes give a very s 

 J factory linear relation between 

 I spark lengths and the volt 

 ' throughout the range studied. 



TABLE 429, - 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, p. 679, 1909. 



SMITHSONIAN TABLES, 



