266 



Notices of Boohs. 



[April, 



storm were taking place there ; this is shown in the following 

 figure (fig. 12). 



The dimensions of sun spots are enormous. In 1858 a spot was 

 noticed which was 107,520 miles long ; and, in the same year, the 

 largest spot ever recorded was first noticed : — " It had a breadth of 



Fig. 12. 



A spot presenting the appearance of cyclonic motion. (Secchi.) 



no lessthan 143,500 miles; so that across it no less than eighteen 

 globes as large as our earth might have been placed side by side." 

 The prominences and the chromosphere form the subject of the 

 following chapter. The former were first examined during the total 

 solar eclipse of 1842, but were perhaps detected in 1733, by Vasse- 

 nius, of Gottenburg. Several subsequent observations were made; 

 the most important, until recently, being those of Mr. De la Rue 

 and Father Secchi, in i860. The prominences were then proved 

 to be real phenomena belonging to the sun, and to possess great 

 luminosity, brilliant colour, and considerable photographic power. 



Fig. 13. 



Illustrating the vast scale of the larger prominences. 



Secchi further noticed that there were " masses of prominence 

 matter suspended and isolated like clouds in the air." The 

 height of the solar prominences is enormous : — 130,000 miles 

 is considered by astronomers no exaggerated amount. The 



