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Authors

David E. Hadden

Document Type

Research

Abstract

The present paper is a continuation of a series of sun-spot observations contributed to the Iowa Academy of Sciences at the annual session in December, 1902. For the purpose of representing graphically the resulting curve of the sunspot cycle which now embraces two maxima and one minimum the numerical summaries of the seventeen year's observations have been plotted. The instruments used were a 4-inch refractor until August, 1907, and after that time a 5½ inch refractor, an 8-inch reflector was also employed and a polarizing eyepiece magnifying about 80 was principally used.

Publication Date

1908

Journal Title

Proceedings of the Iowa Academy of Science

Volume

15

Issue

1

First Page

17

Last Page

24

Copyright

©1908 Iowa Academy of Science, Inc.

Language

en

File Format

application/pdf

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