ii6 



THE POPULAR SCIENCE MONTHLY 



Fig. 10. a, h, spectra of two sun-spots. The triple line indicates a magnetic 

 field of 4,500 gausses in a, and one of 2,000 gausses in b. 



opposite components of a magnetic double line should appear in two 

 such spots. As our photographs show, the result of the test was in 

 harmony with my anticipation. 



I may not pause to describe the later developments of this investiga- 

 tion, though two or three points must be mentioned. The intensity of 

 the magnetic field in sun-spots is sometimes as high as 4,500 gausses, 

 or nine thousand times the intensity of the earth's field. In passing 

 upward from the sun's surface, the magnetic intensity decreases very 



Fig. 11. Right- .\ni> Lki-^-hanukd Vortices siuuoixding Sin-simts indicated by 

 the distril)ution of hydrogen (Ha) gas. rhotographod with the spootroheliograph. 



