160 ON SOME RECENT SUN SPOTS. 



possibly have influence on the plastic nature of the solar 

 envelopes. Sir John Herschell suggested that it might be due 

 to streams of meteors moving in an oval orbit with a period of 

 about eleven years. This idea, though ingenious, is by no means 

 proved. Modern efforts to sustain this cause are still sub judice. 



Time does not permit the discussion of the fascinating subject 

 of the spectroscopic examination of Sun Spots. Moreover, it 

 may still be regarded as in its initial stages. 



The marvellous discovery of Radium and its close association 

 with Helium, which latter metal, or its compounds, is exten- 

 sively found in the solar envelopes, has suggested the thought 

 that Radium may yet prove to be a main cause of solar heat and 

 light. Should this ever be proved, we need not fall back on the 

 gradual shrinking of the sun's mass as a chief cause of the 

 emission of solar heat an idea that does not commend itself to 

 some minds and possibly Radium in its ceaseless activity may 

 originate the vibrations in the all-pervading ether, which 

 occasions the sensation of light and all the phenomena of vision. 



