[445] _The forest fence_: They do not trust themselves so much as to step upon the sand, but look out on it from the verge of the forest which encircles it, and which as they travel they have on the left hand. [446] _Bulicamë_: A hot sulphur spring a couple of miles from Viterbo, greatly frequented for baths in the Middle Ages; and, it is said, especially by light women. The water boils up into a large pool, whence it flows by narrow channels; sometimes by one and sometimes by another, as the purposes of the neighbouring peasants require. Sulphurous fumes rise from the water as it runs. The incrustation of the bottom, sides, and edges of those channels gives them the air of being solidly built. [447] _The passage_: On each edge of the canal there is a flat pathway of solid stone; and Dante sees that only by following one of these can a passage be gained across the desert, for to set foot on the sand is impossible for him owing to the falling flakes of fire. There may be found in his description of the solid and flawless masonry of the canal a trace of the pleasure taken in good building by the contemporaries of Arnolfo. Nor is it without meaning that the sterile sands, the abode of such as despised honest labour, is crossed by a perfect work of art which they are forbidden ever to set foot upon. [448] _The gateway_: At the entrance to Inferno. [449] _Whose king_: Saturn, who ruled the world in the Golden Age. He, as the devourer of his own offspring, is the symbol of Time; and the image of Time is therefore set by Dante in the island where he reigned. [450] _Her child_: Jupiter, hidden in the mountain from his father Saturn.