The doorway of this storehouse lies in the side of a hill. It is twice as wide as the great barn-door where the hay-carts are driven in; and two railroad-tracks run out at it, side by side, with a little foot-path between them. The entrance is light, because it opens so wide; but we can see that the floor slopes downward, and the way looks dark and narrow before us. We shall need a guide; and here comes one,--a rough- looking man, with smutty clothes, and an odd little lamp covered with wire gauze, fastened to the front of his cap. He is one of the workmen employed to bring the treasures out of this dark storehouse; and he will show us, by the light of his lamp, some of the wonders of the place. Walk down the sloping foot-path now, and be careful to keep out of the way of the little cars that are coming and going on each side of you, loaded on one side, and empty on the other, and seeming to run up and down by themselves. But you will find that they are really pulled and pushed by an engine that stands outside the doorway and reaches them by long chains. At last we reach the foot of the slope; and, as our eyes become accustomed to the faint light, we can see passages leading to the right and the left, and square chambers cut out in the solid hill. So this great green hill, upon which you might run or play, is inside like what I think some of those large anthills must be,--traversed by galleries, and full of rooms and long passages. All about we see men like our guide, working by the light of their little lamps. We hear the echoing sound of the tools; and we see great blocks and heaps that they have broken away, and loaded into little cars that stand ready, here and there, to be drawn by mules to the foot of the slope. Now, are you curious to know what this treasure is? Have you seen already that it is only coal, and do you wonder that I think it is so precious? Look a little closer, while our guide lets the light of his lamp fall upon the black wall at your side. Do you see the delicate tracery of ferns, more beautiful than the fairest drawing. See, beneath your feet is the marking of great tree-trunks lying aslant across the floor, and the forms of gigantic palm-leaves strewed among them. Here is something different, rounded like a nut-shell; you can split off one side, and behold there is the nut lying snugly as does any chestnut in its bur! Did you notice the great pillars of coal that are left to uphold the roof? Let us look at them; for perhaps we can examine them more closely than we can the roof, and the sides of these halls. Here are mosses and little leaves, and sometimes an odd-looking little body that is not unlike some of the sea-creatures we found at the beach last summer; and every thing is made of coal, nothing but coal. How did it happen, and what does it mean? Ferns and palms, mosses and trees and animals, all perfect, all beautiful, and yet all hidden away under this hill, and turned into shining black coal.