The carpenter poured a few drops of wine into one of the tumblers, shook it about, turned it into the other, shook it again, and finally poured it on the unctuous stone floor beside him.  Then he filled both glasses to the brim, and both men drank in silence.

They repeated the operation, and after the second glass there was not much left in the measure.  The flabby host had retired to the gloomy vaults within, where he played cards with a crony by the light of a small smoking lamp with a cracked chimney.

“That was the very place, was it not?” asked the carpenter at last, in a low tone, and almost without moving his lips.

The mason said nothing, but shrugged his shoulders, in a sort of enigmatic assent.  Both drank again, and after a long time the carpenter smiled faintly.

“He was looking for the ‘lost water,’” he said, in a tone of contempt.

The faint smile slowly reflected itself in the mason’s face.  The two finished their wine, lit their pipes again, left the price of their drink on the table without disturbing the host and went away.

So far as any outsider could have judged, the expert’s curiosity and the few words exchanged by the workmen referred to the so-called “lost water,” which might be somewhere under the north-west corner of the Palazzo Conti, and no one unacquainted with subterranean Rome could possibly have understood what any of the three meant.

The “lost waters” of Rome are very mysterious.  Here and there, under old streets and far down amongst the foundations of ancient palaces, there are channels of running water which have no apparent connection with any of the aqueducts now restored and in use.  It is a water that comes no one knows whence and finds its way to the Tiber, no one knows how.  It is generally clear and very cold, and in the days when the aqueducts were all broken and most people drank of the river, the “lost water” was highly prized.  It appears in the most unexpected places, sometimes in great quantities and seriously interfering with any attempt to lay the foundations of a new building, sometimes black and silent, under a huge flagstone in an old courtyard, sometimes running with an audible rush through hidden passages deeper than the deepest cellars.  It has puzzled archaeologists, hydraulic engineers and architects for generations, its presence has never been satisfactorily explained, there seems not to be any plan of the city which shows its whereabouts, and the modern improvements of the Tiber’s banks do not appear to have affected its occult courses.  By tradition handed down from father to son, certain workmen, chiefly masons and always genuine Romans, claim to know more about it than other people; but that is as much as can be said.  It is known as the “lost water,” and it rises and falls, and seeks different levels in unaccountable ways, as water will when it is confined under the earth but is here and there confronted by the pressure of the air.