Prof. Pictet on the Ice-caves of the Jura and the Alps. 13 
Our celebrated countryman Saussure bestowed a great deal 
of attention on this phenomenon. The observations and reflec- 
tions which he made on the subject, are to be found in the 3d 
volume of his Travels among the Alps, (p. 1404—1415). I 
shall now proceed to give a short account of them. 
There is near Rome a little hill of 200 or 300 feet high, 
almost entirely composed of broken pieces of urns, and other 
vases of earthen ware, and for this reason called Monte Testa- 
ceo. Several caves have been dug round its base, in the back- 
walls of which chimneys have been opened, and from whence 
there blows into the caves a cold wind which cools them. On 
July 1. 1773, the external air being in the shade at 78°,1 Fah., 
the thermometer remained at 44°| in one of these caves, and at 
44° in another, according to the observations of Saussure. 46 It 
is certainly a very singular phenomenon (says he), that in the 
middle of the Campagna of Rome, where the air is always 
burning hot and suffocating, there should be found a little in- 
sulated hill, from the base of which should issue, on all sides, 
currents of air of an extreme coolness.” 
It is not less singular, he adds, that in a climate still farther 
to the south, and in an island such as Ischia, near Naples, 
which is entirely volcanic, and abounds in hot springs, a cold 
wind, such as we have just described, should occur. Saussure 
found, by the observation he made March 9. 1773, that the 
thermometer was 63°i in the open air, and 45°J at the extremity 
of the grotto. He was told, at the same time, that in the great 
heats of summer he would have found it much lower. 
At the foot of the freestone hill, upon which is situated the 
town of St Marin, at the height of 325 toises above the sea, 
there are likewise cold caves, where, on the 9th of July 1773, 
Saussure found the thermometer at 45 ° \ ; when in the open air it 
was at 61°J. 
In a private house, in the little town of Cosi near Terni, in 
the Papal States, there is a cellar, not very deep, in which a 
cold wind issues with considerable impetuosity from the crevices 
of the rocks, against which it is placed. In July 4. 1773, 
Saussure found that the temperature of this current was 45°, 
while the outward air was 64°6. 
