The original innovator of multiple fire-tubes is unclear, between Stephenson and Marc Seguin. It is known that Seguin visited Stephenson to observe "Locomotion" and that he also built two multi-tubular locomotives of his own design for the Saint-Étienne–Lyon railway before "Rocket". "Rocket"s boiler was of the more highly developed form, with the separate firebox and a blastpipe for draught, rather than Seguin's cumbersome fans, but "Rocket" was not the first multi-tubular boiler, although it remains unclear just whose invention it was.