58 LIGHT SCIENCE FOR LEISURE HOURS. 



The spectroscope, applied successfully at all the 

 observing stations, resolved, in a manner there was no 

 misinterpreting, the problem which had so long per- 

 plexed astronomers. And the strange answer to their 

 questions was this that the coloured prominences are 

 masses of gas glowing with intensity of heat. Those 

 vast and seemingly stable protuberances, so enormous 

 that ten globes like our earth placed one upon the 

 other on the sun's surface would not reach their 

 summit, are flames of hydrogen, that familiar element 

 which constitutes so large a proportion of our ordinary 

 gas flames. Or, rather, they are not strictly flames of 

 hydrogen, but whorls of the gas heated to an intense 

 degree of brightness. And other vapours are also 

 present in these vast glowing masses, since the spec- 

 trum of the prominence-light shows other lines than 

 those which are characteristic of hydrogen. 



I need not recount here in full the interesting 

 history of sequent researches into the prominences. 

 Indeed not the least remarkable feature of that history 

 is the circumstance that the study of the prominences 

 has not continued to be associated (as it had been until 

 the autumn of 1868) with the history of eclipses. 

 First Janssen, afterwards (but independently) Lockyer, 

 succeeded in seeing the bright lines of the prominence 

 spectrum when the sun was shining in full splendour. 

 Then the lower regions of prominence-matter, forming 

 what previous observers had denominated the sierra 

 but named by Lockyer (who was unaware of its prior 

 discovery) the chromosphere was analysed with the 



