To cross a stream, highway or valley (wherever the delay a result of a flight of locks at possibly side can be unacceptable) the valley may be spanned by a navigable aqueduct – a popular illustration in Wales may be the Pontcysyllte Aqueduct (now a UNESCO World Heritage Website) https://urso-fofo33210.buyoutblog.com/37053564/details-fiction-and-canal-infantil