IOWA ACADEMY OF SCIENCES. 88 



a large group of much activity, which passed over to the 

 invisible side of the sun on December 19th. 



1898. 



During the present year fully two-thirds of all the sun- 

 spots observed were small; the number of spotless days 

 slightly increased, and the average number of groups and 

 spots remained fairly steady compared with the preceding 

 year. 



The year under review was also remarkable for the 

 appearance of several fine outburts w^hich occurred in the 

 months of February, March, September, October and 

 November. The group of February 9th to 20th was at 

 first but a few small spots at the east limb, but which in a 

 few days rapidly increased, becoming a very fine train, 

 fully 130,000 miles in length, on the 14th, but much dimin- 

 ished before reaching the west limb. 



Another considerable stream appeared from March 5th 

 to 17th, with dimensions fully as large as the February 

 group, and showing much activity on the 10th. 



By far the greatest and finest group of the year appeared 

 in the month of September, from 2d to 15th; this group 

 probably originated about August 11th, as a cluster of tiny 

 spots, and finally disappeared on November 7th, hence com- 

 pleting four rotations to the central meridian. Appearing 

 at a period of fast approaching minimum, this group was 

 remarkable for its enormous size and associated spectro- 

 scopic and magnetic and electrical manifestations. The 

 following account of it is transcribed from my observing 

 note book: "When I first observed it, but a mere line of 

 light separated it from the edge of the east limb, no penum- 

 bra being visible, except on the north and south edges of 

 the long umbral line; a bright aurora was coincident with 

 its ingress the same evening. On the following day penum- 

 bra was visible on all sides of the umbra and the spot prom- 

 ised to be interesting, the changes from day to day being 

 quite marked. Owing to unsatisfactory atmospheric con- 

 ditions, the spectroscope could not be used until the 6th, 

 when but little or no disturbance could be noticed in the 



