30 



components. If a magnetic field is really at work in 

 sun-spots we should anticipate a close correspond- 

 ence between the behavior of each solar line and 

 its laboratory equivalent. And this is exactly 

 what we find (Fig. 22). Furthermore, the distance 

 between the components of a line is directly pro- 

 portional to the strength of the magnetic field. 

 Thus, by determining the separation correspond- 

 ing to a magnetic field whose strength can be 

 measured in the laboratory, we may easily derive 

 the strength of the field in sun-spots. 



I ? IG. 23. Waterspout off the Coast of Sicily. 

 SUN-SPOTS AND FLOCCULI. 



We can not enter here into the various appli- 

 cations of this conclusion to the explanation of 

 solar phenomena. If w r e could see a single sun- 

 spot from a point beneath the solar surface, it 

 would probably resemble a terrestrial water-spout 

 or tornado, though its cross-section, instead of 

 being a few hundred feet, would be hundreds of 

 miles. The strength of the magnetic field pro- 

 duced, which is measured by the degree of separa- 



