76 IOWA ACADEMY OF SCIENCES. 



greater or more important disturbances will be briefly 

 alluded to, in the following descriptions, which are given 

 for each year. 



1890, (august to December). 



Some large sun-spots appeared on the disc towards the 

 end of August, which practically marked the beginning of 

 the new cycle of solar activity, and which reached a maxi- 

 mum about three years later; the minimum probably 

 occurred towards the middle of the year 1899, and as is 

 usual in sun-spot periodicity, the interval from a mini- 

 mum to maximum is much shorter than the decline from 

 maximum to the next following minimum. 



Large spots were also present during the months of Sep- 

 tember, October, November and December, some especially 

 fine spots being present in the third decade of October. 



1891. 



This year was one of rapid increase in sun-spot activity; 

 there were ten or twelve spotless days in January, a few in 

 February and March, but after that time the disc was not 

 free from spots for a period of about live years. 



Several large and tine groups and spots were observed 

 during the!year, notably those on February 17-2()th, April 

 21-30th, May 19-25th, June 25-30th, July 10-25th and 

 August 29th to September 10th; this last disturbance was 

 especially interesting, being large and easily visible to the 

 naked eye. Unusual activity was present in the group 

 during its transit, and its ingress on the disc was marked 

 by brilliant auroras v;hich continued for three nights; the 

 return of this disturbed area at the east limb on September 

 25th was again attended by brilliant auroras for several 

 evenings. 



Another large disturbance made the transit from Novem- 

 ber 15th to 27th, and is of interest as marking the begin- 

 ning of the giant outburst of 1892, February. 



