THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



1 14 1 



OCTOB-ER 1915k 



XL VIII. A Further Study of the Fluorescence produced 

 by Ultra- Schumann Rays. By C. F. Meyer and R. 

 W, Wood *. 



[Plate VI.] 



IN 1910 one of the writers t described experiments showing 

 the existence of a radiant emission from the spark which 

 had not been previously detected. The subject was more 

 fully investigated in collaboration with G. A. Hemsalech if, 

 and many interesting phenomena observed. All experiments 

 indicated that the emission which was being studied con- 

 sisted of ultra-Schumann waves. No method was found, 

 however, of determining their wave-length, and the experi- 

 mental difficulties throughout the work were so great that 

 many phenomena were only incompletely studied, and many 

 points were left uncertain. The present authors have there- 

 fore attacked the problem anew, and the results they have 

 obtained will be discussed in this paper. 



The radiant emission in question cannot be directly 

 observed or photographed, but its existence is shown by 

 the fluorescence which it causes in certain gases. The 

 essential parts of: the apparatus used in its study were the 

 same as in the above-mentioned investigations, except that 

 the box forming the jet-chamber this time consisted of metal 

 instead of wood. 



* Communicated by the Authors. 



f Wood, Phil. Mag. [6] xx. p. 707 (1910). 



% Wood and Hemsalech, Phil. Mag. [6] xxvii. p. 899 (1914). 



Phil May. S. 6. Vol. SO. No. 178. Oct. 1915. 2 G 



