Almost at starting it was cut through the solid rock, which formed a wall on either side of it, about sixty feet high. You can't imagine how strange it seemed to be journeying on thus, without any visible cause of progress other than the magical machine, with its flying white breath and rhythmical, unvarying pace, between these rocky walls, which are already clothed with moss and ferns and grasses; and when I reflected that these great masses of stone had been cut asunder to allow our passage thus far below the surface of the earth, I felt as if no fairy tale was ever half so wonderful as what I saw. Bridges were thrown from side to side across the top of these cliffs, and the people looking down upon us from them seemed like pigmies standing in the sky. I must be more concise, though, or I shall want room. We were to go only fifteen miles, that distance being sufficient to show the speed of the engine, and to take us on to the most beautiful and wonderful object on the road. After proceeding through this rocky defile, we presently found ourselves raised upon embankments ten or twelve feet high; we then came to a moss, or swamp, of considerable extent, on which no human foot could tread without sinking, and yet it bore the road which bore us. This had been the great stumbling-block in the minds of the committee of the House of Commons; but Mr. Stephenson has succeeded in overcoming it. A foundation of hurdles, or, as he called it, basket-work, was thrown over the morass, and the interstices were filled with moss and other elastic matter. Upon this the clay and soil were laid down, and the road does float, for we passed over it at the rate of five and twenty miles an hour, and saw the stagnant swamp water trembling on the surface of the soil on either side of us. I hope you understand me. The embankment had gradually been rising higher and higher, and in one place, where the soil was not settled enough to form banks, Stephenson had constructed artificial ones of wood-work, over which the mounds of earth were heaped, for he said that though the wood-work would rot, before it did so the banks of earth which covered it would have been sufficiently consolidated to support the road.