The Sun 



less uprushes, doubtless due to variations of 

 temperature, combined with other causes, carry 

 the constituents of the deeper regions into a 

 cooler space, the zone of chemical reactions, or 

 photosphere. In this zone lime, magnesia and 

 carbon are doubtless formed in impalpable 

 powders, and perhaps the refractory metals 

 condense for an instant, forming tiny incan- 

 descent drops; then everything falls back into 

 the superheated abyss of the interior to be 

 volatilised, until a fresh convulsion brings them 

 back into the photosphere. 



These eruptions of central matter attain in 

 places sufficient development and violence to 

 pierce the photosphere, and we can then see 

 through the burning mass of projected gas the 

 dark depths of the nucleus; frequently a spot 

 formed in this manner is rendered more per- 

 manent and regular by the action of vortical 

 movements; in other cases the hole closes after 

 the eruption, and the continuity of the photo- 

 spherj is restored. But even irrespective of 

 spots, the surface is never at rest. Its granula- 

 tions prove its irregularity, and the faculae 



constitute more extended swellings, at times 



187 



