I felt as if suddenly, between sleeping and waking, I had plunged deep into the dusk of dreamland. We rumbled through a lofty egg-shaped vault, lined with masonry, lighted waveringly, with strange play of shadow, by our many lamps. This phase of the dream seemed to last a long time; and then the train of boxes slowed down, for we had reached the danger-point, a part of the tunnel where the hidden Genii of the Mountain had planned a trap to upset all geological expectations. Having allowed the engineers to penetrate thus far, they had suddenly flooded the tunnel with cataracts of water from fissures in the rock, and had laughed wild, echoing laughter because they had contrived to delay the work for a year, and cause the spending of much extra money. The dream showed me now a long iron cage, shoring up the crumbling walls of the excavation; and through this cage we crept like a procession of wary mice, suddenly putting on speed at the end, till we reached the tunnel-head, and found another train preparing to go out. Here the dream flung me into a teeming Inferno of darkness and lost spirits who (spent with eight hours' monotonous toil in this Circle) had dropped asleep, sitting half-naked in the line of boxes which would bear them away to a spell of rest. They had fallen into pathetic attitudes of collapse, some lying back with their mouths open, some resting their heads on folded arms, some drooping on comrades' shoulders. As our train-load of Activity came to a stand, this other train-load of Exhaustion rumbled slowly away, the smoky lamps glinting on polished, olive-coloured flesh, on hairy arms, and swarthy faces shut to consciousness. Close to the tunnel-head we alighted, and went on into the dream on foot, the gallery contracting to a few feet in height, where a group of black figures bent over rock-drills which creaked and groaned. I saw the drill-holes filled with dynamite, and retired with the others while the fuse was lighted. I heard from afar off the thunderous detonations as the rock-face was shattered. I saw the débris being cleared away, before the drills should begin to grind again; and the remembrance that, in another rathole on the Swiss side, another party of workers was patiently advancing towards us, in precisely the same way, sent a mysterious thrill through my blood. "Suppose the two galleries don't meet end to end?" I spoke out my thought. "But they will," said Bolzano. "Our calculations are precise, and we have allowed for an error of two inches: I do not think there will be more. There is a great system of triangulation across the mountains, and every few months our reckonings are verified. By-and-bye, we shall hear the sound of each other's drills; then, down will come the last dividing wall of rock, and Swiss and Italians will be shaking hands."