An automatic fountain the sprays water vertically when a bus passes over that spot on the second floor,the floor directly under the Roof Garden.

The sculpture consists of seven sections of wind-animated panels, approximately 10-feet square that are suspended above people's heads by a series of 8-inch diameter stainless steel poles. The panels are composed of thousands of small anodized aluminum elements that are hinged to move freely in the wind.[from UO Library Website]