In 1955, the first solar-powered car was publicly demonstrated. It was a 15-inch Sunmobile built by William G. Cobb of the General Motors Corporation. Light energy falling on 12 selenium photoelectric cells created electric current to power a tiny electric motor that turned a driveshaft connected to the car's rear axle by a pulley. It was one of 253 free exhibits of the General Motors Powerama, Chicago, Ill. seen by over 2,500,000 visitors during this 28-day, $7,000,000 event spread over 1,000,000 sq ft on the shore of Lake Michigan. It showcased the company's modern diesel power, including an oil well, cotton gins, cranes, earth-movers, trucks, tractors, military equipment, a submarine, a shrimp boat, Aerotrain, an aluminium foundry and other machinery.«[Image: the lightweight Aerotrain was displayed at Powerama.]