To cross a stream, highway or valley (wherever the delay a result of a flight of locks at possibly facet might be unacceptable) the valley could be spanned by a navigable aqueduct – a well-known illustration in Wales would be the Pontcysyllte Aqueduct (now a UNESCO Globe Heritage Web https://judahmvadg.wssblogs.com/36993975/considerations-to-know-about-musica-infantil