To cross a stream, street or valley (where by the delay brought on by a flight of locks at possibly side might be unacceptable) the valley is often spanned by a navigable aqueduct – a popular instance in Wales could be the Pontcysyllte Aqueduct (now a UNESCO Globe Heritage https://sethwdhmp.bloggactivo.com/36310101/the-single-best-strategy-to-use-for-musica-infantil