My father was an audio engineer, a mastering engineer. He went way back, in the business, even before digital. The processes he was concerned with were partly mechanical, with that clunky quasi-Victorian quality you see in twentieth-century technology. He was a lathe operator, basically. People brought him audio recordings and he burned their sounds into grooves on a disk of lacquer. Then the disk was electroplated and used in the construction of a press that would stamp out records, the black things you see in antique stores. And I remember him telling me, once, a few months before he died, that certain frequencies transients, I think he called them could easily burn out the head, the cutting head, on a master lathe. These heads were incredibly expensive, so you prevented burnouts with something called an accelerometer. And that was what I was thinking of, as I stood there, my toes out over the water: that head, burning out.