To cross a stream, street or valley (the place the delay attributable to a flight of locks at either side could well be unacceptable) the valley may be spanned by a navigable aqueduct – a famous case in point in Wales is definitely the Pontcysyllte Aqueduct (now a UNESCO https://canalinfantil56654.blognody.com/41588211/how-much-you-need-to-expect-you-ll-pay-for-a-good-musica-infantil