Hanging the photos is the second part of a project that Greenberg began in 2016, when he set out to rephotograph the locations of all the springs and wells described by Smith, on foot or by bike. In 2021, Greenberg published a four-hundred-and-ninety-six-page book that combines Smith’s befores with his contemporary afters, the overlap offering provocative serendipities: a drain where a well once was, a fire hydrant at a former water-pump site. Naturally, most of Greenberg’s pictures show dry land, though not all. “There’s still a spring in Central Park, near Eighty-second Street, and I did find some other springs in the northern part of the Park that Smith had photographed,” he said. “Up in St. Nicholas Park, the springs were rearranged when they built the modern water tunnel in the nineteen-teens. But when you see a stairway and there’s water flowing down it, if it’s not right after a rain, then that’s a spring.”