IOWA ACADEMY OF SCIENCES. 79 



1894. 



Like the preceding year, the one now under review was 

 also noted for the persistence of large and very interesting 

 sun-spot groups. Every month of the year witnessed some 

 "greater sun-spot disturbance," thus while the crest of the 

 sunspot curve was undoubtedly passed in the late summer 

 of 1893, the decline was marked at first and then became 

 more gradual with a slight revival until midsummer of 

 1894, after which time a more pronounced and steady 

 decline set in, until the minimum epoch. 



In January a large group visible to the naked eye was 

 present. During February a spot 48,000 miles in length 

 was an interesting object; its umbra, on the 19th, when 

 examined by means of the spectroscope, was the location 

 of brilliant reversals of the Ha line, and when the slit of 

 the instrument was widely opened the reversal presented a 

 flame or tree-like appearance. On the 25th bright reversals 

 took place in the penumbra of the same spot. 



Large double spots, with variously formed nuclei were 

 transiting the disc during the first week in April; and in. 

 May and June splendid groups of wonderfully complicated 

 and intricate markings were of fascinating interest. 



On June 7th a remarkable eruptive prominence was 

 observed with the spectroscope, consisting of "spikes" and 

 "flames," which was in violent commotion; its height was 

 estimated to be 70,000 miles; ten minutes later the entire 

 disturbance had nearly subsided, the shifting of the Ha 

 line towards the blue end of the spectrum indicated a rapid 

 approach in a direction towards the earth; later the region 

 of the photosphere further in, on the disc was violently 

 agitated, the Ha line appeared with blow-pipe looking jets 

 directed towards the red end of the spectrum. Single and 

 composite groups of great size and beauty were noted in 

 August, September, October and December, with much 

 spectroscopic disturbance and strong reversals of Hydrogen 

 lines in the large group of October 6th. 



