This march became more and more laborious. The level of these vaults varies; the average height is about five feet, six inches, and has been calculated for the stature of a man; Jean Valjean was forced to bend over, in order not to strike Marius against the vault; at every step he had to bend, then to rise, and to feel incessantly of the wall. The moisture of the stones, and the viscous nature of the timber framework furnished but poor supports to which to cling, either for hand or foot. He stumbled along in the hideous dung-heap of the city. The intermittent gleams from the air-holes only appeared at very long intervals, and were so wan that the full sunlight seemed like the light of the moon; all the rest was mist, miasma, opaqueness, blackness. Jean Valjean was both hungry and thirsty; especially thirsty; and this, like the sea, was a place full of water where a man cannot drink. His strength, which was prodigious, as the reader knows, and which had been but little decreased by age, thanks to his chaste and sober life, began to give way, nevertheless. Fatigue began to gain on him; and as his strength decreased, it made the weight of his burden increase. Marius, who was, perhaps, dead, weighed him down as inert bodies weigh.