306 LIGHT SCIENCE FOR LEISURE HOURS. 



regions at a rate not of so many miles per hour or per 

 minute, but of many miles, sometimes more than a 

 hundred miles, in every second of time. Such storms 

 are in progress now, where we see the spots upon the 

 sun. Such storms tell us of the activity of that great 

 central engine whose throbs are the life-beats of the 

 solar system. 



We measure the sun's work, perforce, by our own 

 forms of work. We speak of his emission of light and 

 heat as corresponding to what would result from the 

 burning of eleven thousand millions of millions of tons 

 of the finest coal in every second of time. But what 

 mind can conceive the real vitality of that mighty orb 

 which seems so silent and so still in our skies ? The 

 throbbing of the great engine which beats out light 

 and life to the whole family of planets can only be 

 seen by the mind's eye, and as yet that eye is no more 

 capable of seeing the sun's work as it really is than is 

 the bodily eye of seeing the distant millions of suns 

 which the great gauging telescopes of the Herschels 

 bring within our ken. Nor can the mental ear hearken 

 to the uproar and tumult with which the work of the 

 great central engine is accomplished, or imagine what 

 would be heard if one could visit that spot which looks 

 like a tiny speck on the sun's surface, and, passing 

 below the limits of the solar air so that sound waves 

 could reach him, could find (as assuredly he would 

 if he could live at a temperature which turns the 

 hardest metal into vapour) all forms of noise known 

 to us the roar of the typhoon, the crash of thunder, 



