To cross a stream, street or valley (in which the delay attributable to a flight of locks at either facet might be unacceptable) the valley is often spanned by a navigable aqueduct – a popular instance in Wales will be the Pontcysyllte Aqueduct (now a UNESCO Planet Heritage Website) https://canalinfantil12211.thezenweb.com/facts-about-urso-fofo-revealed-75333370