MIRACLES OF SCIENCE 



foot reflector since then installed at the Mt. Wilson 

 observatory. 



Of course nebulae were no new discovery. A cer- 

 tain number of them had been observed since tele- 

 scopes were invented. One or two are even faintly 

 visible, like misty stars, to the naked eye. But the 

 importance of Professor Keeler's observations con- 

 sisted (1) in showing the vast abundance of these 

 curious structures, and (2) in revealing the very strik- 

 ing fact that a large preponderance of the nebulae 

 have a spiral structure. As the photographic film 

 was made to supplement direct vision, revealing ten- 

 uosities of nebular structure that the eye cannot de- 

 tect, it beca'me increasingly evident that the spiral is, 

 so to say, the typical form of nebulae as a class. And 

 this suggested some highly interesting questions as 

 to method of world building, as will appear in a 

 moment. 



Quite aside from their relation to world-making, 

 however, these spiral nebulae are telescopic objects 

 of peculiar picturesqueness. They seem to be great 

 luminous whirlpools of incandescent matter. Perhaps 

 to the average eye they suggest more than anything 

 else the popular and familiar type of fireworks called 

 the pin-wheel. 



If you partially close your eyes and look at the 

 photograph of a spiral nebula (a particularly good 

 one is here reproduced) you can easily imagine that 

 it represents a whirligig of fire, two revolving points 

 making a pair of entwined incandescent spirals, and 

 the sputtering flames sending out clouds of sparks 

 and luminous smoke in an ever-widening circle. 



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