"By my observation we are at 10,000 feet below the level of the sea." "Is that possible?" "Yes, or figures are of no use." The Professor's calculations were quite correct. We had already attained a depth of six thousand feet beyond that hitherto reached by the foot of man, such as the mines of Kitz Bahl in Tyrol, and those of Wuttembourg in Bohemia. The temperature, which ought to have been 81° (178° Fahr.) was scarcely 15° (59° Fahr.). Here was cause for reflection. CHAPTER XIX. GEOLOGICAL STUDIES IN SITU Next day, Tuesday, June 30, at 6 a.m., the descent began again. We were still following the gallery of lava, a real natural staircase, and as gently sloping as those inclined planes which in some old houses are still found instead of flights of steps. And so we went on until 12.17, the precise moment when we overtook Hans, who had stopped. "Ah! here we are," exclaimed my uncle, "at the very end of the chimney." I looked around me. We were standing at the intersection of two roads, both dark and narrow. Which were we to take? This was a difficulty. Still my uncle refused to admit an appearance of hesitation, either before me or the guide; he pointed out the Eastern tunnel, and we were soon all three in it. Besides there would have been interminable hesitation before this choice of roads; for since there was no indication whatever to guide our choice, we were obliged to trust to chance. The slope of this gallery was scarcely perceptible, and its sections very unequal. Sometimes we passed a series of arches succeeding each other like the majestic arcades of a gothic cathedral. Here the architects of the middle ages might have found studies for every form of the sacred art which sprang from the development of the pointed arch. A mile farther we had to bow our heads under corniced elliptic arches in the romanesque style; and massive pillars standing out from the wall bent under the spring of the vault that rested heavily upon them. In other places this magnificence gave way to narrow channels between low structures which looked like beaver's huts, and we had to creep along through extremely narrow passages. The heat was perfectly bearable. Involuntarily I began to think of its heat when the lava thrown out by Snæfell was boiling and working through this now silent road. I imagined the torrents of fire hurled back at every angle in the gallery, and the accumulation of intensely heated vapours in the midst of this confined channel. I only hope, thought I, that this so-called extinct volcano won't take a fancy in his old age to begin his sports again! I abstained from communicating these fears to Professor Liedenbrock. He would never have understood them at all. He had but one idea--forward! He walked, he slid, he scrambled, he tumbled, with a persistency which one could not but admire. By six in the evening, after a not very fatiguing walk, we had gone two leagues south, but scarcely a quarter of a mile down.