Chapter XX: The Walls of Pedro Miguel

This was drawn from the opposite end of the lock and the great side walls topped with their concrete-making crenellations and cranes are seen. In the foreground, on the left, is one of the side openings for emptying the water from one lock to another--for all the locks are double, side by side, and ships will not have to wait until a lock is empty, as is usual, before they can enter, but, as one empties, the same water partly fills the one beside it, and so steamers will pass without waiting. Two or three small vessels can go through at the same time, as well as the largest with room to spare.