My last paper contributed to the Academy of Science on solar observations covered the period 1903 to 1907 and was published in the Proceedings for 1908, Volume XV. The present paper brings the observations down to the close of 1920 and completes a series embracing thirty years of sun-spot observations. They do not pretend to be as complete during the last decade of this long period as for the first twenty years for the reason that I was appointed a member of the State Pharmacy Board in 1909, serving eleven years, and the duties of the office called me away from home very frequently, consequently the number of days on which the sun could be observed was materially diminished each year. The observations represent the result of painstaking work during the intervals snatched from a busy business life and are presented to indicate what may be done by anyone, even if handicapped by numerous other duties, in this fascinating branch of astronomy.
Proceedings of the Iowa Academy of Science
©1921 Iowa Academy of Science, Inc.
Hadden, David E.
"The Solar Surface during the past Thirteen Years - A Review of Sun-Spot Observations Made at Alta, Iowa from 1908 to 1920,"
Proceedings of the Iowa Academy of Science, 28(1), 121-126.
Available at: https://scholarworks.uni.edu/pias/vol28/iss1/26