I'm standing on the second floor of a flour mill looking at a giant flour sifter built in the late 1800's. The flour mill is now a furniture store, but many of its artifacts (water wheel, etc.) remain intact. A man in his late 30's with his lovely wife and daughter come up the stairs.
"Do you know what this is?" he asks. "It's a pipe organ pump." He then goes on to explain some of the parts they're looking at, how they work together, and muses, "I wonder if we can see more of it downstairs."