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Dr. John B. Dalton demonstrating a comparison microscope

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Photograph of Dr. John B. Dalton demonstrating a comparison microscope

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Dr. John B. Dalton demonstrates a comparison microscope, ca. 1935.

© St. Paul Police Historical Society

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St. Paul Police Historical Society

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St. Paul Police Department Reform, 1933–1940

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Science and Technology

Made possible by the Arts and Cultural Heritage Fund through the vote of Minnesotans on November 4, 2008. Administered by the Minnesota Historical Society.
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