walk round the temples, and returned to our new acquaintance, who led the way through the gate of the city to the banks of a pool or lake a short distance off.  We walked to the borders on a mass of calcareous tufa, and we saw that this substance had even encrusted the reeds on the shore.  There was something peculiarly melancholy in the character of this water; all the herbs around it were grey, as if encrusted with marble; a few buffaloes were slaking their thirst in it, which ran wildly away on our approach, and appeared to retire into a rocky excavation or quarry at the end of the lake; there were a number of birds, which, on examination, I found were sea swallows, flitting on the surface and busily employed with the libella or dragon-fly in destroying the myriads of gnats which rose from the bottom and were beginning to be very troublesome by their bites to us.  “There,” said the stranger, “is what I believe to be the source of those large and durable stones which you see in the plain before you.  This water rapidly deposits calcareous matter, and even if you throw a stick into it, a few hours is sufficient to give it a coating of this substance.  Whichever way you turn your eyes you see masses of this recently-produced marble, the consequence of the overflowing of the lake during the winter floods, and in that large excavation where you saw the buffaloes disappear you may observe that immense masses have been removed, as if by the hand of art and in remote times.  The marble that remains in the quarry is of the same texture and character as that which you see in the ruins of Paestum, and I think it is scarcely possible to doubt that the builders of those extraordinary structures derived a part of their materials from this spot.”  Ambrosio gave his assent to this opinion of the stranger; and I took the liberty of asking him as to the quantity of calcareous matter contained in solution in the lake, saying that it appeared to me, for so rapid and considerable an effect of deposition, there must be an unusual quantity of solid matter dissolved by the water or some peculiar circumstance of solution.  The stranger replied, “This water is like many, I may say most of the sources which rise at the foot of the Apennines:  it holds carbonic acid in solution which has dissolved a portion of the calcareous matter of the rock through which it has passed.  This carbonic acid is dissipated in the atmosphere, and the marble, slowly thrown down, assumes a crystalline form and produces coherent stones.  The lake before us is not particularly rich in the quantity of calcareous matter that it contains, for, as I have found by experience, a pint of it does not afford more than five or six grains; but the quantity of fluid and the length of time are sufficient to account for the immense quantities of tufa and rock which in the course of ages have accumulated in this situation.”  Onuphrio’s curiosity was excited by this statement of the stranger, and he said, “May I take the