"Can it be for ventilation only? But a ventilation hole could only communicate with one of the apartments in the Palais itself, and how the deuce could they drop a corpse down there? It would have been in the highest degree imprudent to attempt it! No, it is not by that road they have carried off Dollon's body! But then by what way?" He glued his ear to the chimney. After a while, Fandor could make out a vague, intermittent sound--could catch a little, far-away, plashing sound. "Can the chimney communicate with the Seine?" he asked himself. "No, we are too far off it. Why this opening, then?... Ah, I have it! It is a drain, a sewer, it communicates with!" To verify that, there was nothing for it but to descend this chimney, which was no chimney! So be it!... Fandor took off his coat, and uncovered the long, fine cord, rolled round and round his middle. Weighting the cord with a flint, he let it slide down the chimney, testing the straightness of the descent by the balanced oscillations of the stone, and so ascertaining the even size of the opening, as far as the line would go. This was the work of a few minutes. Fandor did not hesitate: he was eager to embark on the descent. "After all," he murmured, "though I may find myself face to face with a band of assassins--what of it? It is all in the night's risks!" He fastened the end of the cord to one of the neighbouring chimneys--fastened it firmly; then, his revolver handily stuck in his belt, Fandor seized the cord, twisted it round his legs, and let himself slowly down through the narrow opening. It was a perilous descent! Fandor did not know whether his cord was long enough, and, lost in the darkness, with only the gleam of light from his lantern to guide him, he was naturally afraid of reaching the end of his rope unawares, and of falling into the black void beneath. But what he observed in the course of his descent excited him so much that he almost forgot the danger he was running. To those at all practised in police detective work, it was clear as daylight that men had passed this way, and recently. "Here is a dislodged stone," muttered Fandor. "And here are scrapes and scratches--fresh ... and ... that mark looks like blood!" Pushing his knees and his shoulders against the wall to support himself and stay his movements, he examined the mark. There was no doubt possible: Fandor's sharp eyes and the lantern's light had picked out a little red patch, which sullied one of the projecting stones in the chimney walls: "This," reflected our amateur detective, "only confirms Dollon's death: if the wound which caused this mark had been made by a living body, the mark would have been larger, and there would have been others, for it must come from an abrasion of the skin made during the descent. But this blood mark has resulted from a dead body knocking against the stones of the wall: it is not a mark make by flowing blood, but by blood crushed out." He descended a few yards further: