River Thrum, 1985, by Robert Morrison, is a sound sculpture: a sequence, or phrase, of standing steel plates aligned on a tracklike armature of channel iron and wood. It sits on the south bank of the Truckee River, behind the Sierra Nevada Museum of Art, and looks, at various turns, like a futuristic sailing device, a stand of winter trees in a place Walter Van Tilburg Clark once called the “city of trembling leaves,” and a mechanical, even instrumental, equivalent of the river itself.

The sound River Thrum makes is implied in its title—a twitching, crusty, distant metallic sound that resonates