"I was far from sure that I was not in a dream. We rattled with great rapidity through such a labyrinth of streets, that I soon lost all idea where we were; except that we had crossed and re-crossed the river, and still seemed to be traversing a low-lying, water-side, dense neighbourhood of narrow thoroughfares, chequered by docks and basins, high piles of warehouses, swing-bridges, and masts of ships."

Except for the mention of the river and ships, I would not have known what a swing bridge was. I have only seen one, and it was so long ago I can't remember where it was. The bridge is pivoted at one end, and can swing parallel to the river, to let a boat pass, with comparatively little powere required to move it.
Here's a picture of a swing bridge, but it is pivoted in the middle, and obviously only for very light traffic.
http://www.ambergriscaye.com/pages/photos/477.html