High above the stage of Historic Thalian Hall is a unique piece of theatre history: the only theater in the country that still creates an indoor thunderstorm using an original 19th century theatrical sound effect system known as the Thunder Roll. It uses angled wooden troughs where cannon balls are released in sequence, along with a wooden cylinder turned to imitate rain and a thunder sheet shaken and struck to produce the clap of thunder. The resulting thunderstorm has delighted audiences from the age of candlelight to today, and this 19th century technology is still occasionally used in productions.