INDEXED, 6 / 7 



THE / 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



• — ♦ 



[SIXTH SERIES.] 



DEC EMBER 1905. 



LXX. The Relation betiveen P.D.and Spark-length for Small 

 Values of the latter. By Glenn Moody Hobbs *. 



[Plate XIII.] 



I. Introduction. 



rilHE general subject of spark-discharge in gases has 

 JL commanded the attention of investigators for many 

 years, but the recent developments of" the electron theory 

 have brought it into especial prominence within the last half- 

 decade. The particular investigations on the spark-discharge 

 between two electrodes and the potential necessary to produce 

 discharge with varying distances have extended over a period 

 of forty-five years,, the first observations being made in 1860 

 bv Lord Kelvin t. Since 1880, the field has been covered 

 more rapidly and important investigations have been made 

 by Bailie t, Liebig§, Paschen ||, Peace % Strutt** Boutytt, 

 Earhart % t, and Carr§§. During this period the general 

 behaviour of the discharge between electrodes throughout 



0. * Communicated by the Author. 



t Lord Kelvin, " Collected Papers on Electrostatics and Magnetism," 

 p. 247. 



X Bailie, Annates de Chimie et de Physique [5] xxv. p. 486 (1882). 



§ Liebig, Phil. Mag. [5] xxiv. p. 106 (1887). 



|| Paschen, Wied. Ann. xxxvii. p. 79 (1889). 



% Peace, Proc. Roy. Soc. lii. p. 99 (1892). 

 ** Strutt, Phil. Trans, cxciii. p. 377 (1900). 

 ft Bouty, Comptes Rendus, cxxxi. pp. 469, 503 (1900). 

 XX Earhart, Phil. Mag. [6] i. p. 147 (1901). 

 §§ Carr, Proc. Roy. Soc. lxxi. p. 374 (1903). 



Phil. Mag. S. 6. Vol. 10. No. 60. Dec. 1905. 2 U ' 



