126 
IOWA ACADEMY OF SCIENCE Voi.. XXVIII, 1921 
The telescope was partly dismounted for repairs during the 
months of November and December, 1909, and January, 1910. 
During the years 1917 to 1920 owing to the war and scarcity 
of business help, numerous absences from home, personal losses 
by deaths, etc., the time devoted to the work was necessarily lim- 
ited and the full daily observations not completed, hence only the 
daily average number of groups are given in the following tables : 
Average Daiey Number oe Groups 
Months 
1917 
1918 
1919 
1920 
January 
6.7 
6.8 
4.0 
2.0 
February 
5.0 
4.8 
5.3 
4.0 , 
March 
6.8 
5.2 
4.8 
3.0 
April 
6.5 
5.7 
4.2 
1.5 
May 
7.0 
5.5 
5.3 
3.0 
June 
8.3 
4.8 
7.0 
2.4 
July 
8.5 
6.9 
4.6 
August 
10.0 
6.7 
4.7 
1.4 
September 
9.0 
5.6 
4.4 
1.7 
October 
5.2 
5.9 
4.2 
3.4 
November 
6.9 
5.7 
2.9 
2.0 
December 
7.5 
4.8 
2.8 
1.8 
Reviewing the observations of the thirty years which embraced 
three maximum and three minimum periods, the following dates 
have been derived: 
Minimum of 1889.6 to the maximum of 1893.7 
Maximum of 1893.7 to the minimum of 1901.5 
Minimum of 1901.5 to the maximum of 1905.9 
Maximum of 1905.9 to the minimum of 1913.5 
Minimum of 1913.5 to the maximum of 1917.7 
Minimum of 1889.6 to the minimum of 1901.5 
Minimum of 1901.5 to the minimum of 1913.5 
Maximum of 1893.7 to the maximum of 1905.9 
Maximum of 1905.9 to the maximum of 1917.7 
Astronomical and Meteorological Observatory, 
Alta, Iowa. 
4.1 years, 
7.8 years, 
4.4 years, 
7.6 years, 
4.2 years, 
11.9 years, 
12.0 years, 
12.2 years, 
11.8 years, 
