Hello Anya. The bridge was pulled over to the opposite bank by chains/ropes fixed to each side of the lake. Imagine a rubber band with a cardboard matchbox attatched to it. Stretch it out over two sticks ( not too tight). Now if one side of the band is pulled at one of the sticks, the matchbox will move to the other stick, and vise versa. Hope this explains..Best Wishes.William :