It was while testing the latest model of his invention that Roy Emerson made his next breakthrough—and, once again, he was very lucky that no one else had thought of it first.

His ’04 Mercedes Hydro was cruising in benign silence down Park Avenue, living up to its celebrated slogan “You can drink your exhaust!” Midtown seemed to have been hit by a monsoon: conditions were perfect for testing the Mark V Wave Wiper. Emerson was sitting beside his chauffeur—he no longer drove himself, of course—quietly dictating notes as he adjusted the electronics.

The car seemed to be sliding between the rain-washed walls of a glass canyon. Emerson had driven this way a hundred times before, but only now did the blindingly obvious hit him with paralyzing force.

Then he recovered his breath, and said to the carcom: “Get me Joe Wickram.”

His lawyer, sunning himself on a yacht off the Great Barrier Reef, was a little surprised by the call.

“This is going to cost you, Roy. I was just about to gaff a marlin.”

Emerson was in no mood for such trivialities.

“Tell me, Joe—does the patent cover all applications—not just car windshields?”

Joe was hurt at the implied criticism.

“Of course. That’s why I put in the clause about adaptive circuits, so it could automatically adjust to any shape and size. Thinking of a new line in sunglasses?”

“Why not? But I’ve got something slightly bigger in mind. Remember that the Wave Wiper doesn’t merely keep off water—it shakes off any dirt that’s already there. Do you remember when you last saw a car with a really dirty windshield?”