es, so
fatal to the peasants who remain in the summer and autumn in the
neighbourhood of the maremme of Rome, Tuscany, or Naples." The stranger
said, "I am acquainted with the opinions of the gentlemen, and they
undoubtedly have weight; but that a specific matter of contagion has not
been detected by chemical means in the atmosphere of marshes does not
prove its non-existence. We know so little of those agents that affect
the human constitution, that it is of no use to reason on this subject.
There can be no doubt that the line of malaria above the Pontine marshes
is marked by a dense fog morning and evening, and most of the old Roman
towns were placed upon eminences out of the reach of this fog. I have
myself experienced a peculiar effect upon the organs of smell in the
neighbourhood of marshes in the evening after a very hot day; and the
instances in which people have been seized with intermittents by a single
exposure in a place infested by malaria in the season of fevers gives, I
think, a strong support to something like a poisonous material existing
in the atmosphere in such spots; but I merely offer doubts. I hope the
progress of physiology and of chemistry will at no very distant time
solve this important problem." Ambrosio now came forward, and bowing to
the stranger, said he took the liberty, as he saw from his familiarity
with the cicerone that he was well acquainted with Paestum, of asking him
whether the masses of travertine, of which the Cyclopean walls and the
temples were formed, were really produced by aqueous deposition from the
River Silaro, as he had often heard reported. The stranger replied,
"that they were certainly produced by deposition from water; and such
deposits are made by the Silaro. But I rather believe," he said, "that a
lake in the immediate neighbourhood of the city furnished the quarry from
which these stones were excavated; and, in half an hour, if you like,
after you have finished your examinations of the temples with your guide,
I will accompany you to the spot from which it is evident that large
masses of the travertine, marmor tiburtinum, or calcareous tufa, have
been raised." We thanked him for his attention, accepted his invitation,
took the usual 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 th