As we advance there seems no end to the visionary enchantment which surrounds us.
"In the midst of this fantastic scenery are vast ranges of walls, which seem the productions of art, so regular is the workmanship.

They rise perpendicularly from the river, sometimes to the height of one hundred feet, varying in thickness from one to twelve feet, being as broad at the top as below.

The stones of which they are formed are black, thick, durable, and composed of a large portion of earth, intermixed and cemented with a small quantity of sand and a considerable proportion of talk (talc) or quartz.

These stones are almost invariably regular parallelopipeds of unequal sizes in the wall, but equally deep and laid regularly in ranges over each other like bricks, each breaking and covering the interstice of the two on which it rests; but though the perpendicular interstice be destroyed, the horizontal one extends entirely through the whole work.

The stones are proportioned to the thickness of the wall in which they are employed, being largest in the thickest walls.