Erin Overbey writes: “On a recent Tuesday, Bruce Janu, the head librarian at John Hersey High School, in Arlington Heights, Illinois, was rummaging through an old storage cabinet in his new office. Janu, a former history teacher and documentary filmmaker, became the librarian at the school in July. ‘On one of those shelves was this small plastic bag hidden way in the back,’ he said. ‘So I reached in and pulled out an original issue of The New Yorker from August 31, 1946, and it had a narrow white band around it, which read Hiroshima: This entire issue is devoted to the story of how an atomic bomb destroyed a city.’”