To cross a stream, street or valley (in which the delay brought on by a flight of locks at either aspect would be unacceptable) the valley is often spanned by a navigable aqueduct – a well known case in point in Wales is definitely the Pontcysyllte Aqueduct (now a https://dallastcmbs.mybloglicious.com/57119188/the-definitive-guide-to-canal-infantil