60 A CENTURY'S PROGRESS IN ASTRONOMY. 



magnetic disturbances have been made use of 

 by Maunder in his remarkable studies, prom- 

 ulgated in 1904, of the connection between 

 sun-spots and terrestrial magnetism. Maunder 

 finds that on the average magnetic storms are 

 dependent on the presence of sun-spots, and on 

 the size of the spot. The magnetic action, he 

 finds, does not radiate equally in all directions 

 from the sun-spots, but along definite and 

 restricted lines. 



Herschel's hypothesis of a dark and cool 

 globe beneath the solar photosphere was seen 

 to be untenable after the introduction of the 

 spectroscope. The first important theory as to 

 the solar constitution was that advanced in 

 1865 by the French astronomer, Herve Faye 

 (1814-1902). Numerous other theories were 

 afterwards advanced by Secchi, Zollner, Young, 

 and others, but a complete description of the 

 various developments in solar theorising cannot 

 be given here. There is no complete " theory " 

 of the exact constitution of every part of the 

 Sun, but the unpretentious "Views of Professor 

 Young on the Constitution of the Sun," which 

 appeared in April 1904 in 'Popular Astronomy/ 

 represent the latest ideas of the foremost solar 

 investigator. Professor Young regards the re- 

 versing layer and the chromosphere as "simply 



