THE PHENOMENA OF LIGHT 345 



ing of ether waves of different frequency (number per sec- 

 ond) gives rise to all color effects, however wide their range 

 in beauty and character. The waves per second said to give 

 rise to the colors of the spectrum from red at one end of the 

 scale to violet at the other extreme, are numbers so great as 

 to be incomprehensible. This does not in any way make the 

 theory less tenable, or its mathematical relationships less 

 sure. It has been mathematically demonstrated that when 

 once the wave theory is accepted all these color positions in a 

 spectrum follow naturally. Spectrum analysis in Physics, 

 in Chemistry, in Astronomy, and in the arts and industries, 

 with its arrangement of color lines in order of refrangibility, 

 makes possible a knowledge of the chemical composition 

 of highly heated bodies at distances as great as that of the 

 sun. Even the stars, at distances enormously greater, re- 

 veal in their stellar spectra, something of their composition 

 and of their motions. 



The fact that the solar spectrum not only contains the 

 different colors distinguishable by the eye, but that they 

 blend imperceptibly into one another in order of wave 

 frequency, suggests that in the sunlight there are all lengths 

 of ether waves 1 . The prism serves to sort out and group 

 those of the same or approximately the same frequency. 

 Not only does light from different sources vary in the num- 

 ber of the color elements present, but it varies even more in 

 the proportions in which these are blended. 



When physicists make studies of the solar spectrum in a 

 room from which all other light is excluded, they find that 

 in the region beyond the violet end there is evidence of the 

 existence of ether waves of greater frequency (shorter wave- 

 length) than the violet. These waves are of too great fre- 



1 The lengths of the various ether waves causing color sensations is calcu- 

 lated by dividing the velocity of light (about 186,000 miles per second) by the 

 number of waves per second for any color. 



