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 

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

 ler, Ann. d. i'hys. 28, p. 585, 1909. 



The specially constructed elec- 

 trodes for tlie columns headed 

 "cup electrodes" had the form of 

 a projecting knob 3 cm. in diame- 

 ter and havnig 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 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-Bomstein- 

 Meyerhnffer). 



For long spark lengths in various gases see Voege, Electrotecbn. Z. 28, 1907. For dielectric strength of air and COj 

 in cylindrical air condensers, see Wien, Ann. d. Phys. 39, p. 679, 1909. 



Smithsonian Tables. 



