Book Collectors and Their Hobbies (1913)
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Here "hobbies" means focus or area of interest - no information about which collector built toothpick castles or which maintained an aquarium of exotic goldfish. One section, for instance, runs Dante, Darley Illustrations, Dartmouth College, Defoe (Daniel), Delaware and Detroit, Michigan. I have no idea what use any of this is today but still some of us may find it amusing to flip through. What are "Dances of Death" and how many books could there have been? Or why there are only two people for Latin classics when Whistler has seven? And I can't help but wonder about the person in Chicago who specialized in Lithuanian Folk-Lore. There's one entry for Erotica which at this time seems somewhat bold - there are three under Curiosa, the more common book collector euphemism. (Though there is also one for Phallic Worship.) Note Eugene V. Debs listed under Socialism. In any case, this particular scanned copy seems to have been used fairly often, it's at least marked up fairly well.