124 
IOWA ACADEMY OF SCIENCE Vol. XXVIII, 1921 
the year, those of February, August and September being of giant 
magnitudes. The great spot of August was noteworthy for its in- 
tricate penumbra containing numerous large unjbrae and nuclei, 
and the auroras which were coincident with its passage across 
the disc. 
2, The greatest activity of the present cycle seems to have cul- 
minated in the months of August and September and undoubtedly 
the maximum was passed by the month of October, as a period of 
lesser activity had then set in, 
1918 
1918 opened with numerous spot groups on the disc, many of 
which were large, but the number gradually waned until June when 
they were fewer and of much smaller size. A slight increase in 
numbers took place in July and August, but this diminished during 
the balance of the year, although with large spots still on the disc 
every month. Auroras also were quite frequent this year. 
1919 
There was but a slight reduction in the average number of groups 
per day in 1919 as compared with the preceding year. The first 
half was the more active, the number reaching a maximum in June 
and gradually waning during the latter half. 
• 1920 
A decided decline in numbers of groups was noted this year, the 
average per day for the year being slightly over one-half less than 
in 1919, Nevertheless some very large active groups were ob- 
served, perhaps the finest being the one of March 15 to 27, which 
extended nearly 250,000 miles and was exceedingly active. Its 
passage across the central meridian was nearly coincident with a 
wide-spread display of aurora on the 22-23d. 
Some, spotless days were noted in April and August. In Sep- 
tember another period of considerable activity set in, some fine 
large spots and extended streams being noted. These continued 
into October, after which a quiescent period again set in. ‘ 
In the following tables are given the monthly summaries of the 
daily observations : 
