144 



Dr. W. J. S. Lockyer. 



[Jan. 16, 



In these curves each broad vertical line corresponds to the solar 

 equator, and the scales to the right and left of each represent the 

 north and south latitudes respectively. The heights of the curves 

 above each horizontal zero line indicates the different amounts of 

 spotted area, and the scales of these are so arranged that the curves 

 are all proportional to the spotted area. 



The curves themselves are formed by determining the mean spotted 



Fig. 1. 



(879 



' 1880 A 



A\ JL 



40 30 20-10 +10 20 30 40 40 30 20-10 +10 20 30 40 40 30 20-10 +10 20 30 40 

 S N S N S N. 



TEN-DEGREE ZONES. FIVE-DEGREE ZONES. THREE-DEGREE ZONES. 



DISTRIBUTION OF SUN'S SPOTTED AREA. 

 FROM 1679-1883. 



area for each zone, and plotting each value at the point representing 

 the mean latitude of this zone; these points are then all joined 

 together. Thus, in the case of the — 10° zone, the mean spotted area 

 is plotted at 5°, 10 — 20°, at 15°, etc. The other zone divisions are 

 similarly treated, thus, — 5° is plotted at 2 "5°, — 3° at 1'5°, etc. 



In the 10° zone curves here shown there is only one maximum 

 in each hemisphere for the years in question, and these, as indicated by 

 the dotted curves which join them, do not progress gradually towards 



