To cross a stream, highway or valley (where by the hold off due to a flight of locks at either aspect can be unacceptable) the valley could be spanned by a navigable aqueduct – a renowned example in Wales is the Pontcysyllte Aqueduct (now a UNESCO Environment Heritage Website) https://musica-infantil86274.free-blogz.com/84353648/the-single-best-strategy-to-use-for-musica-infantil