Spark-gap transmitter circuit from Guglielmo Marconi's controversial patent no. 763772 for a "four circuit" wireless telegraphy radio communication system. This patent was the foundation of the Marconi Company's dominance of the wireless business during the first decades of the 20th century. It was contested by Oliver Lodge, Nikola Tesla, and John Stone Stone as violating their prior patent rights, and became the focus of a long running litigation. It was overturned in 1943 by the US Supreme Court.