To cross a stream, street or valley (exactly where the hold off caused by a flight of locks at either side might be unacceptable) the valley is often spanned by a navigable aqueduct – a popular case in point in Wales is definitely the Pontcysyllte Aqueduct (now a UNESCO https://musicainfantil77654.ampblogs.com/top-guidelines-of-urso-fofo-73836255