RECENT SOLAR RESEARCHES. 93 



another vapor, whose nature is as yet undetermined, 

 while occasionally there are the vapors of other ele- 

 ments. But in the chromosphere there are commonly 

 several elements, and sometimes there are many. 



Here, then, we have above the photosphere of the 

 sun a vaporous envelope, obviously of a complicated 

 structure, and perhaps far more complicated than it has 

 yet been proved to be. For it must be remembered 

 that the lowest layers of this envelope might be com- 

 posed of the vapors of numerous elements, and yet no 

 record of their existence be recognized. A depth of 

 ten miles would correspond to so small a portion of 

 the sun's diameter (about the 85,000th part) as to be 

 w T holly unrecognizable by any telescopic power men 

 can hope to obtain. If any of our readers are telesco- 

 pists, they will know what force lies in the remark that 

 such a distance would subtend about the 44th part 

 of a second of arc, so that no less than twenty-six such 

 distances could be placed between the components of 

 that well-known test-object, the double companion of 

 the star Gamma Andromedoe.* 



Next below this colored envelope there is the 

 mottled photosphere, either a white-hot surface with 



* The view here presented was completely confirmed during the 

 eclipse of last December. Professor Young and Mr. Pye independently 

 recognized a layer whose spectrum showed all the Fraunhofer lines 

 reversed. By observing at the place where the moon had just concealed 

 the last fine sickle of the solar.disk, they obviated the effects of diffrac- 

 tion, which render the observation wholly impossible in the case of the 

 uneclipsed sun. 



