Paris on the right bank. The Grand Sewer, which is, it must be remembered, nothing else than the old brook of Ménilmontant, terminates, if one ascends it, in a blind sack, that is to say, at its ancient point of departure which was its source, at the foot of the knoll of Ménilmontant. There is no direct communication with the branch which collects the waters of Paris beginning with the Quartier Popincourt, and which falls into the Seine through the Amelot sewer above the ancient Isle Louviers. This branch, which completes the collecting sewer, is separated from it, under the Rue Ménilmontant itself, by a pile which marks the dividing point of the waters, between upstream and downstream. If Jean Valjean had ascended the gallery he would have arrived, after a thousand efforts, and broken down with fatigue, and in an expiring condition, in the gloom, at a wall. He would have been lost.
In case of necessity, by retracing his steps a little way, and entering the passage of the Filles-du-Calvaire, on condition that he did not hesitate at the subterranean crossing of the Carrefour Boucherat, and by taking the corridor Saint-Louis, then the Saint-Gilles gut on the left, then turning to the right and avoiding the Saint-Sebastian gallery, he might have reached the Amelot sewer, and thence, provided that he did not go astray in the sort of F which lies under the Bastille, he might have attained the outlet on the Seine near the Arsenal. But in order to do this, he must have been thoroughly familiar with the enormous madrepore of the sewer in all its ramifications and in all its openings. Now, we must again insist that he knew nothing of that frightful drain which he was traversing; and had anyone asked him in what he was, he would have answered: “In the night.”
His instinct served him well. To descend was, in fact, possible safety.
He left on his right the two narrow passages which branch out in the form of a claw under the Rue Laffitte and the Rue Saint-Georges and the long, bifurcated corridor of the Chaussée d’Antin.