For the 1904 St. Louis World's Fair, Lewis had the world's largest carbon arc searchlight installed atop the dome, 135 feet above street level. An eight-ton, 80-inch light built by General Electric in 1903, the searchlight developed at least 1 billion candlepower. The searchlight has a seven-foot carbon arc that is “ignited by carbon rods and reflected in a ground glass mirror that magnifies the light.”