VI.] 



IRON IN THE SUN. 



75 



employed, I believe that each coincidence observed by me be- 

 tween an iron line and a line in the solar spectrum, may be 

 considered to be at least as well established as the coincidence 

 of the sodium lines." 



Then he shows, limiting his attention to sixty of the most 

 denned iron lines in the region included in his map, that the 

 probability that there is iron in the sun is about three tril- 

 lions to one, dealing alone with the absolute matching of the 

 positions of the lines recorded in the solar spectrum. Then he 

 goes on to show that this probability of three trillions to one 



FIG. 32. Arrangement of apparatus for observing the spectra of substances 

 volatilised by the electric spark. 



was rendered still greater by the fact that the brighter a given 

 iron line is seen to be, the darker "as a rule" and I beg atten- 

 tion to those words " as a rule " " does the corresponding solar 

 line appear. Hence this coincidence must be produced by some 

 cause, and a cause can be assigned which affords a very perfect 

 explanation of the phenomenon." He then gives the cause 

 which has already been stated in Chapter V. 



Now before I go further I must point out that there is a 

 considerable assumption here. It is quite easy in an electric 

 lamp to produce the vapour of a meteorite or of any of our 



