

434 THE CHEMISTRY OF THE SUN. [CHAP. 



The accompanying curves give Sporer's results of the quan- 

 tity of spotted area between the years 1856 and 1880, the 

 maximum area being taken as 100. It will be seen that there 

 were practically no spots in 1856, the maximum was reached in 

 1860; again, that there were practically no spots in 1867, and 

 the maximum was again reached in 1871. 



FIG. 129. Sporer's curve, showing amount of spotted area during the 

 sun-spot cycle. 



We now come I think to one of the most interesting con- 

 clusions to which the hypothesis naturally leads us, although so 

 far the phenomena have resisted explanation. 



15. By the hypothesis this increase in the numbers and intensity 

 of the falls must end in so increasing the temperature and possibly 

 the height of the atmosphere, that the descending materials are 

 dissociated before they reach the photosphere ; the production of 

 spots therefore gradually diminishes until finally the spot pro- 

 ducing material descends as gentle rain ; the spots disappear and 

 the cycle is ended. 



If we now study Sporer's curves side by side, we find that 

 after the maximum spotted area is reached some four years after 

 each cycle commences, the area diminishes gradually during 

 the next seven years, and that the diminution is much more 

 gentle the curve is much less steep than the increase. 



