The man’s clothing seems more appropriate to the office than to the field (or the lab, for that matter), but I suppose the rolled sleeves indicate that he is “at work.”
I don’t think you could find a clearer illustration of the twentieth-century effort to bring lab-like instrumentation and rigor to field biology. Of course, most biologists didn’t approach the “lab in the field” with such literal-mindedness.
According to this account by Bill Amos, the Nikon H, which was only on the market for a few years, was based on a field-microscope design from the 1930s.
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