To cross a stream, road or valley (exactly where the delay caused by a flight of locks at either side will be unacceptable) the valley could be spanned by a navigable aqueduct – a well-known example in Wales could be the Pontcysyllte Aqueduct (now a UNESCO World Heritage Site) https://musicainfantil90987.oblogation.com/36162285/the-definitive-guide-to-urso-fofo