I leaped up on the rock; my uncle lightly followed, while our hunter remained at his post, like a man too wise ever to be astonished. We walked upon granite mingled with siliceous tufa. The soil shivers and shakes under our feet, like the sides of an overheated boiler filled with steam struggling to get loose. We come in sight of a small central basin, out of which the geyser springs. I plunge a register thermometer into the boiling water. It marks an intense heat of 325°, which is far above the boiling point; therefore this water issues from an ardent furnace, which is not at all in harmony with Professor Liedenbrock's theories. I cannot help making the remark. "Well," he replied, "how does that make against my doctrine?" "Oh, nothing at all," I said, seeing that I was going in opposition to immovable obstinacy. Still I am constrained to confess that hitherto we have been wonderfully favoured, and that for some reason unknown to myself we have accomplished our journey under singularly favourable conditions of temperature. But it seems manifest to me that some day we shall reach a region where the central heat attains its highest limits, and goes beyond a point that can be registered by our thermometers. "That is what we shall see." So says the Professor, who, having named this volcanic islet after his nephew, gives the signal to embark again. For some minutes I am still contemplating the geyser. I notice that it throws up its column of water with variable force: sometimes sending it to a great height, then again to a lower, which I attribute to the variable pressure of the steam accumulated in its reservoir. At last we leave the island, rounding away past the low rocks on its southern shore. Hans has taken advantage of the halt to refit his rudder. But before going any farther I make a few observations, to calculate the distance we have gone over, and note them in my journal. We have crossed two hundred and seventy leagues of sea since leaving Port Gräuben; and we are six hundred and twenty leagues from Iceland, under England. [1] [1] This distance carries the travellers as far as under the Pyrenees if the league measures three miles. (Trans.) CHAPTER XXXV. AN ELECTRIC STORM _Friday, August 21_.--On the morrow the magnificent geyser has disappeared. The wind has risen, and has rapidly carried us away from Axel Island. The roarings become lost in the distance. The weather--if we may use that term--will change before long. The atmosphere is charged with vapours, pervaded with the electricity generated by the evaporation of saline waters. The clouds are sinking lower, and assume an olive hue. The electric light can scarcely penetrate through the dense curtain which has dropped over the theatre on which the battle of the elements is about to be waged.