Malipieri drew back and showed it to his man, who examined it, understood, and put it into his pocket without a word. Then they both went in through the aperture in the wall.
The masonry outside was rectangular, as far as it could be seen. Inside, it was built like a small circular cistern, smoothly cemented, and contracting above in a dome, that opened by a square hole to the well-shaft above. Like the stones in the outer chamber, the cement was coated with scales of dried mud. The shaft was now certainly closed at the top, for in the daytime not a ray of light penetrated into its blackness.
The lanterns illuminated the place completely, and the two men looked about, searching for some new trace of a living being. The yellow light fell only on the remains of men dead long ago. Some of the bones lay as they had lain since then, when the drowned bodies had gently reached the floor as the "lost water" subsided. Malipieri had not touched them, nor Masin either. Two skeletons lay at full length, face downwards, as a drowned body always sinks at last, when decay has done its loathsome work. A third lay on its side, in a frightfully natural attitude, the skull a little raised up and resting against the cemented wall, the arms stretched out together, the hands still clutching a rusty crowbar. This one was near the entrance, and if, in breaking their way in, Malipieri and Masin had not necessarily destroyed the cement on each side of the slit, they would have found the marks where the dead man's crowbar had worked desperately for a few minutes before he had been drowned. Malipieri had immediately reflected that the unfortunate wretch, who was evidently the mason of whom Sassi had told him, had certainly not entered through the aperture formerly made from above in the outer chamber, since the narrow slit afforded no possible passage to the well. That doubtless belonged to some other attempt to find the treasure, and the fact that the mason's skeleton lay inside would alone have shown that he had got in from above, most likely through a low opening just where the dome began to curve inward. A further search had discovered some bits of wood, almost rotted to powder, which had apparently once been a ladder.
A much less practised eye than the architect's would have understood at a glance that if a living man were let down through the shaft in the centre of the dome, and left on the floor, he could not possibly get up even as far as the other hole, since the smooth cement offered not the slightest hold; and that if the outflow of the stream from the first chamber were arrested, the water would immediately fill it and rise simultaneously in the well, to drown the victim, or to strip his bones by its action, if he had been allowed to die of hunger or thirst. It was clear, too, that if the latter form of death were chosen, he must have suffered to the last minute of his life the agony of hearing the stream flowing outside, not three paces from him, beyond the slit. Human imagination could hardly invent a more hideously cruel death-trap, nor one more ingeniously secret from the world without.
The unhappy mason's ladder had perhaps broken with his weight, or his light had gone out, and he had then been unable to find the horizontal aperture, but he had probably entered through the latter, when he had met his fate. The fact was, as Malipieri afterwards guessed, that the hole through the vault outside had been made hastily after the accident, in the hope of recovering the man's body, but that it had been at once closed again because it appeared to open over a deep pit full of still water.
A stout rope ladder now dangled from the lateral aperture in the dome, which Malipieri had immediately understood to have been made to allow the water to overflow when the well was full. He had also felt tolerably sure that the well itself had not been originally constructed for the deadly use to which it had evidently been put in later times, but for the purpose of confining the water in a reservoir that could be easily cleaned, since it could be easily emptied, and in which the supply could be kept at a permanent level, convenient for drawing it from above. In the days when all the ancient aqueducts of Rome were broken, a well of the "lost water" was a valuable possession in houses that were turned into fortresses at a moment's notice and were sometimes exposed to long and desperate sieges.
In order to reach the horizontal opening, Malipieri had climbed upon Masin's sturdy shoulders, steadying himself as well as he might till he had laid his hands on the edge of the orifice. As he hung there, Masin had held up the handle of a pickaxe as high as he could reach against the smooth wall, as a crossbar on which Malipieri had succeeded in getting a slight foothold, enough for a man who was not heavy and was extraordinarily active. A moment later he had drawn himself up and inward. At the imminent risk of his life, as he afterwards found, he had crawled on in total darkness till the way widened enough for him to turn round and get back. He had then lowered a string he had with him, and had drawn up a lantern first, then the end of a coil of rope, then the tools for carrying on the exploration. The rest had been easy. Masin had climbed up by the rope, after making knots in it and when Malipieri had called out, from the inner place to which he had retired with the end, that it was made fast. But the light showed the architect that in turning round, he had narrowly escaped falling into an open shaft, of which he could not see the bottom, but which was evidently meant for the final escape of the overflowing water.
There was room to pass this danger, however, and they had since laid a couple of stout boards over it, weighted with stones to keep them in place. Beyond, the passage rose till it was high enough for a man to walk upright. Judging from the elevation now reached this passage was hollowed in the thickness of one of the main walls of the palace, and it was clear that the water could not reach it. A few yards from the chasm, it inclined quickly downwards, and at the end there were half a dozen steps, which evidently descended to a greater depth than the floor of the first outer chamber.
So far as it had hitherto been possible to judge, there was no way of getting to these last steps, except that opened by the two men, and leading through the dry well. In former times, there might have been an entrance through the wall at the highest level, but if it had ever existed it had been so carefully closed that no trace of it could now be found.
This tedious explanation of a rather complicated construction has been necessary to explain what afterwards happened. Reducing it to its simplest terms, it becomes clear that if the water rose, a person in the passage, or anywhere beyond the overflow shaft, could not possibly get back through the well, though he would apparently be safe from drowning if he stayed where he was; and to the best of Malipieri's knowledge there was no other way out. Any one caught there would have to wait till the water subsided, and if that did not happen he would starve to death.