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 might be spanned by a navigable aqueduct – a renowned instance in Wales may be the Pontcysyllte Aqueduct (now a UNESCO Globe Heritage Site) https://cristianxcfjm.blogpayz.com/37293119/the-definitive-guide-to-canal-infantil