To cross a stream, highway or valley (where by the delay brought on by a flight of locks at possibly facet could well be unacceptable) the valley could be spanned by a navigable aqueduct – a well known instance in Wales could be the Pontcysyllte Aqueduct (now a UNESCO https://urso-fofo89876.collectblogs.com/81776621/not-known-facts-about-canal-infantil