212 THE SUN-SPOTS OF THE PAST FEW YEARS. 



Furthermore, comparing the number of spots which 

 has appeared during this spot-period with those of the 

 two preceding periods, we find that the number of this 

 period has been smaller. 



Still another difference presents itself, which I will 

 give from the records of the Potsdam Observatory. 



Dr. Spoerer, of the Potsdam Observatory, is an assid- 

 uous observer of sun phenomena, and he has recently 

 published in the Astronomische Nachrichten interesting- 

 results deduced from his researches of the past few 

 years, combined with investigations based upon a series 

 of observations covering thirty years. He directs his at- 

 tention especially to the distribution of the spots rela- 

 tively to heliocentric latitude. It has for some years 

 been noticed that during minimum the altitude attained 

 by the spots is lower than during maximum. In 1883 

 Spoerer published in the Nachrichten a table which 

 gives the distribution of spots in zones of 5° of latitude, 

 during a period of thirty years. The appearance of the 

 table is at once striking to the eye, since its arrangement 

 shows the regular run of values. This regularity was 

 so marked that Spoerer ventured to predict the behavior 

 of the spots in this regard during 1884 ; that is, that the 

 greatest spot-number would occur in the zone between 

 10° and 15°, and that the zone beyond this, 15° — 20°, 

 would be less abundantly supplied than the one below T , 

 i. e., 5° — 10°. The observations of 1884 verified his sup- 

 position. The largest number of spots has appeared in 

 zone 10° — 15°, while in the zone 5° — 10° the number is 

 more than twice that of 15° — 20°. This prediction, how- 

 ever follows from the portions of the table immediately 

 preceding 1884, and not upon the conditions of previous 

 maximum. Here enters an important difference. Al- 

 though the maximum epoch has been delayed or pro- 

 longed, the mean latitude of largest frequency has been 

 lowered. The mean latitude during previous maxi- 



196 



