MARY WHITNEY. 211 



mean of those to 1878.8 we have 1882.8. Wolf s theoret- 

 ical mean would place it earlier, and Spoerer's later, at 

 1883.5. 



The display of 1882 was so remarkable that some ob- 

 servers considered that the period was then completed. 

 This was the opinion of Faye as late as April, 1884. He 

 regarded the great outburst of April, 1882, as indicative 

 of maximum, and held that the display of April and 

 July, 1883, were secondary maxima, which often occur 

 in the progress of periodic phenomena. Wolf considered 

 in the spring of 1884 that the question was still open. 



Consulting our record, I find that in 1883 there were 

 four days without visible spot. In 1884 I find but one 

 day — November 8th. I notice that Prof. Todd, of Am- 

 herst, gives also the date November 7th, but I have 

 recorded one small spot for that day. On January 12th, 

 1885, there was no spot seen by my assistant who was 

 then making the count. 



During the two years the highest monthly number 

 occurred in July, 1883, the month of the belt of which I 

 have sj)oken. Directly following, however, there is a 

 rapid fall. There is a rise again in October, with a fall 

 succeeding ; but not so low a number is reached as in the 

 preceding fall. In January, 1884, a rise again occurs, 

 and the number keeps high through February, March 

 and April. May and June give diminishing numbers ; 

 and the monthly numbers have continued compara- 

 tively small up to this time. 



I give on page 205 the diagram I have constructed from 

 my values. Judging from this, I incline to place the 

 maximum epoch early in 1884, since the longest sus- 

 tained activity occurs at that time. 



Spoerer, in his last publication in the Astronomische 

 Nachricliten, places it provisionally at 1884.0. Appar- 

 ently, then, the maximum is late, even if we regard the 

 latest theoretical epoch 1883.5 as the most correct one. 



195 



