There were also deep, wide ditches, through which a stream of liquid lava had flowed since the petrifaction of the main body through which it passed. Cascades of fire are said to be often seen in the course of these canals or rivers as they leap some precipice, presenting in the night a scene of unequaled splendor and sublimity. In some places the banks or dikes of these rivers are excavated and fallen in with hideous crash and ruin; and often you may go up, if you dare, to the edge on one side and look over into the gulf, and away under the opposite overhanging bank, where the igneous fluid has worn away and scooped it out till the cliff hangs on air, and seems to topple and lean, like the tower of Pisa, just ready to fall. It would be no very comfortable reflection, if a man were not too curiously eager and bold and intent upon the novelties he is drinking in by the senses, to have much reflection or fear at such a time, to think how easily an earthquake might tumble down the bank on which he is standing, undermined in like manner with that which you are looking at right opposite. On our left, as we passed on to the Great Caldron, we explored, as far as was possible between the heat and vapor, the great bank, or, more properly, mountain-side of sulphur and sulphate of lime (plaster of Paris), and obtained some specimens of no little beauty. There are cliffs of sulphur through which scalding hot vapor is escaping as high up above you as eight hundred feet; and lower down there are seams from which lambent and flickering flames are darting, and jets of hot air will sometimes whirl by you, involving no little danger by their inhalation. Around these fissures are yellow and green incrustations of sulphur, which afford a new variety of specimens. When we had got to the leeward of the caldron, we found large quantities of the finest threads of metallic vitrified lava, like the spears and filaments of sealing-wax, called Pele's hair. The wind has caught them from the jets and bubbling springs of gory lava, and carried them away on its wings till they have lodged in nests and crevices, where they may be collected like shed wool about the time of sheep-shearing. Sometimes this is found twenty miles to the leeward of the volcano. The heat and sulphur gas, irritating the throat and lungs, are so great on that side, that we had to sheer away off from the brim of the caldron, and could not observe close at hand the part where there was the most gushing and bubbling of the ignifluous mineral fluid. But we passed round to the windward, and were thus enabled to get up to the brim so as to look over for a minute in the molten lake, burning incessantly with brimstone and fire-- "A furnace formidable, deep, and wide, O'erboiling with a mad, sulphureous tide."