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.