PORTION OF THE COSMOS. THE SUN. 295 



tained, by the help of photographic apparatus, combined 

 with mechanical clockwork movement, an uninterrupted 

 series of graphical representations of solar spots ( 492 ). 

 Meteorological processes taking place in the gaseous enve- 

 lopes of the dark solar body cause the phenomena which 

 we term solar spots and condensed luminous clouds. There, 

 as well as in the meteorology of our own planet, the disturb- 

 ances are probably so varied and complicated in their kind, 

 and so intricate in respect to the causes in which they origi- 

 nate, and which are partly general and partly local, that it 

 is only by long-continued observation, aiming at the greatest 

 attainable completeness, that we can hope to resolve even a 

 portion of the still obscure problems which they present. 



