﻿i 9 i6] BOVIE— SCHUMANN RAYS 19 



Angstrom units. A measurement of the energy of the spectrum 

 (which was made with a bolometer) showed that the amount of 

 energy decreased with the decreasing wave length; but that in a 

 region nearly coinciding with the region in which the destructive 

 action of the light fell off the amount of energy increased, so that, 

 when the two curves, the energy curve and the destructive curve, 

 are compared, the one is seen to be the inverse of the other. The 

 depression in the destructive curve and the elevation in the energy 

 curve do not quite coincide, but Bang attributed this to a slight 

 shift in some part of his spectrograph. 



Hertel (21) used quartz lenses and a quartz prism to form a 

 spectrum of the light from various spark gaps. He measured, by 

 means of a thermopile, the energy of the light of various wave 

 lengths which he allowed to fall upon living tissues. He found that 

 the destructive action of the light varies directly as the energy, and 

 inversely as the wave length. He did not find the two maxima 

 described by Bang. 



Henri (19, 20) in 191 2 measured the relative destructive action 

 of light of various wave lengths. He used as sources of light a 

 mercury vapor arc in quartz, and spark gaps with cadmium and 

 magnesium terminals. The relative intensity of the light of various 

 wave lengths was measured by the effect upon a photographic plate. 

 He made use of screens for filtering out the various wave lengths. 

 The efficiency of the screens was determined by spectrographs 

 methods. He found that the destructive action of the light 

 increases continuously as the wave length decreases. Henri did 

 not find a secondary maximum at 3500 Angstrom units, as reported 

 by Bang. With the exception of Bang, these investigators have 

 agreed that, in the regions of the spectrum studied, the destructive 

 action of light increases as the wave length decreases. None of 

 their investigations have included the region of the spectrum lying 

 below wave length 2000 Angstrom units. 



In the experiments described in this paper the relation between 

 the wave length and the destructive action in the Schumann region 

 has been studied. Because of the small amount of energy in the 

 Schumann rays, no attempt has been made to measure the intensity 

 of the light of the various wave lengths. A knowledge of the 



