290 CELESTIAL DYNAMICS. 



sun's surface, in spite of the great heat, such substances as 

 water may possibly exist in the liquid state under a pressure 

 thousands of times greater than that of our atmosphere. 



Since gases, when free from any solid particles, emit, even 

 at very high temperatures, a pale transparent light the so- 

 called lumen philosophicum it is probable that the intense 

 white light of the sun has its origin in the denser parts of his 

 surface. If such be assumed to be the case, the sun's spots 

 and faculae seem to be the disturbances of the fiery liquid 

 ocean, caused by most powerful meteoric processes, for which 

 all necessary materials are present, and partly to be caused 

 by the direct influence of streams of asteroids. The deeper 

 and less heated parts of this fiery ocean become thus exposed, 

 and perhaps appear to us as spots, whereas the elevations 

 form the so-called faculse. 



According to the experiments made by Henry, an Ameri- 

 can physicist, the rays sent forth from the spots do not pro- 

 duce the same heating effect as those emitted by the brighter 

 parts. 



We have to mention one more remarkable circumstance. 

 The spots appear to be confined to a zone which extends 30 

 on each side of the sun's equator. The thought naturally 

 suggests itself that some connexion exists between those solar 

 processes which produce the spots and faculae, the velocity of 

 rotation of the sun, and the swarms of asteroids, and to de- 

 duce therefrom the limitation of the spots to the zone men- 

 tioned. It still remains enigmatical by what means nature 

 contrives to bring about the uniform radiation which pertains 

 alike to the polar and equatorial regions of the sun. 



