Note 220 — CANTO IV.

Thundering sound: In a state of unconsciousness, Dante, he knows not how, has been conveyed across Acheron, and is awakened by what seems like the thunder-peal following the lightning-flash which made him insensible. He now stands on the brink of Inferno, where the sounds peculiar to each region of it converge and are reverberated from its rim. These sounds are not again to be heard by him except in their proper localities. No sooner does he actually pass into the First Circle than he hears only sighs.—As regards the topography of Inferno, it is enough, as yet, to note that it consists of a cavity extending from the surface to the centre of the earth; narrowing to its base, and with many circular ledges or terraces, of great width in the case of the upper ones, running round its wall—that is, round the sides of the pit. Each terrace or circle is thus less in circumference than the one above it. From one circle to the next there slopes a bank of more or less height and steepness. Down the bank which falls to the comparatively flat ground of the First Circle they are now about to pass.—To put it otherwise, the Inferno is an inverted hollow cone.