To cross a stream, street or valley (where the hold off because of a flight of locks at possibly facet might be unacceptable) the valley can be spanned by a navigable aqueduct – a famed case in point in Wales is definitely the Pontcysyllte Aqueduct (now a UNESCO Environment https://jaidenhqwad.jiliblog.com/93559374/musica-infantil-for-dummies