To cross a stream, road or valley (exactly where the delay caused by a flight of locks at possibly aspect will be unacceptable) the valley may be spanned by a navigable aqueduct – a well-known example in Wales is the Pontcysyllte Aqueduct (now a UNESCO Environment Heritage Web page) https://urso-fofo90998.csublogs.com/44490691/helping-the-others-realize-the-advantages-of-musica-infantil