To cross a stream, road or valley (where the hold off because of a flight of locks at possibly facet might be unacceptable) the valley might be spanned by a navigable aqueduct – a popular instance in Wales will be the Pontcysyllte Aqueduct (now a UNESCO World Heritage Site) https://cristianxcfjm.blogpayz.com/37293119/the-definitive-guide-to-canal-infantil