The effect was magical! Hans, who carried the second apparatus, had it also put into operation. This ingenious application of electricity to practical purposes enabled us to move along by the light of an artificial day, amid even the flow of the most inflammable and combustible gases. "Forward!" cried my uncle. Each took up his burden. Hans went first, my uncle followed, and I going third, we entered the somber gallery! Just as we were about to engulf ourselves in this dismal passage, I lifted up my head, and through the tubelike shaft saw that Iceland sky I was never to see again! Was it the last I should ever see of any sky? The stream of lava flowing from the bowels of the earth in 1219 had forced itself a passage through the tunnel. It lined the whole of the inside with its thick and brilliant coating. The electric light added very greatly to the brilliancy of the effect. The great difficulty of our journey now began. How were we to prevent ourselves from slipping down the steeply inclined plane? Happily some cracks, abrasures of the soil, and other irregularities, served the place of steps; and we descended slowly; allowing our heavy luggage to slip on before, at the end of a long cord. But that which served as steps under our feet became in other places stalactites. The lava, very porous in certain places, took the form of little round blisters. Crystals of opaque quartz, adorned with limpid drops of natural glass suspended to the roof like lusters, seemed to take fire as we passed beneath them. One would have fancied that the genii of romance were illuminating their underground palaces to receive the sons of men. "Magnificent, glorious!" I cried in a moment of involuntary enthusiasm, "What a spectacle, Uncle! Do you not admire these variegated shades of lava, which run through a whole series of colors, from reddish brown to pale yellow--by the most insensible degrees? And these crystals, they appear like luminous globes." "You are beginning to see the charms of travel, Master Harry," cried my uncle. "Wait a bit, until we advance farther. What we have as yet discovered is nothing--onwards, my boy, onwards!" It would have been a far more correct and appropriate expression, had he said, "let us slide," for we were going down an inclined plane with perfect ease. The compass indicated that we were moving in a southeasterly direction. The flow of lava had never turned to the right or the left. It had the inflexibility of a straight line. Nevertheless, to my surprise, we found no perceptible increase in heat. This proved the theories of Humphry Davy to be founded on truth, and more than once I found myself examining the thermometer in silent astonishment.