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Published
Published
Photoelectric relay made at Yerkes Observatory, Williams Bay, Wisconsin, with the cooperation of the General Electric Co., and photoelectric cells by R. J. Cashman and W. S. Huxford, 1933. Courtesy of the Adler Planetarium.
Published
Published
WWI helmet, (1917) worn by by Kent Hagler (shown in framed image) during his service in France.