SUN SPOTS 161 



undoubtedly excellent observations he was too hasty in 

 what he then wrote, and too rash in the conclusions 

 he then drew. But let it be recorded to his honour 

 that to him belongs the credit of first sending the 

 beams of Sirius and other sunny stars through a prism, 

 for the purpose of determining whether their light is 

 like our sun's or not. It was a most brilliant idea, 

 carried out before the world was ready to receive it. 



The great question Herschel set himself to solve 

 regarding the sun was, What is it ? He knew, as all 

 men had known, that it was a vast fiery ball ruling 

 earth and sky ; but he saw, as they saw, nothing save 

 the outside of the ball. Was it a mighty furnace 

 within as it was without ? In Newton's days, two or 

 three generations earlier, there were people who 

 " supposed the sun to be cold," although Newton easily 

 showed that, to "a body hard by the sun, his heat 

 would be 50,000 times greater than we feel it in a hot 

 summer day, which is vastly greater than any heat we 

 know on earth." 1 Herschel was aware that the spots, 

 the black spots on its face, were vast dark holes in its 

 white brightness, so large that they would let the 

 earth dive in, and be at a thousand miles' distance 

 all round from the burning, blazing clouds. But while 

 he knew this, he had also learned from the writings of 

 others that these black rifts were careering over its face 

 from west to east at the rate of more than a mile 

 every second. What did it all mean, was the question 

 he wished answered. Fabricius in 1611, and Galileo 

 about the same time, divide between them the honour 

 of discovering these spots on the sun's face. The 

 former tells the story of his first sight of a spot, of his 



1 Brewster, Life, ii. 455. 

 II 



