Alone in the walnut-paneled music room, his favorite of Fair Lane Mansion’s 56 rooms, automobile tycoon Henry Ford picks up one of his two Stradivarius violins. It is 1920 or so and Henry, cocooned in his woolen three-piece suit despite the summer heat, stretches his bow arm for a little elbow and shoulder room.

Henry plucks the A string uncertainly, then steps to the grand piano at the far end of the room and searches the keyboard for A. Counting forward on the white keys from Middle C – C, D, E, F, G, A – he pokes at the A, then plucks the A string of his violin again. His ear hears the same pitch. Unison, they call it, a good name for the sound of happy hands on his assembly line. He plucks the other strings and touches a couple of tuning pegs lightly, but doesn’t adjust them. Close enough.