These were the original seven locks arranged in a staircase at Rogny, now called Rogny-les-Sept-Écluses. In a lock-staircase the upper door of one lock is the lower door of the next lock. In a seven lock staircase there can only be boats going up or boats going down as obviously crossing is impossible. As this was not very practical when the canal was heavily used by commercial barges the staircase was replaced at the end of the 19th century by six separate locks.