On Architecture

3. Consequently those who think that they have excavated sources of springs at the height of such hills find themselves mistaken when they open up their excavations. Suppose a bronze vase filled not to the very lips, but containing two thirds of the quantity of water which forms its capacity, and with a cover placed upon it. When it is subjected to a very hot fire, the water must become thoroughly heated, and from the rarity of its nature it greatly expands by taking in the heat, so that it not only fills the vase but raises its cover by means of the currents of air in it, and swells and runs over. But if you take the cover off, the expanding forces are released into the open air, and the water settles down again to its proper level. So it is with the sources of springs. As long as they are confined in narrow channels, the currents of air in the water rush up in bubbles to the top, but as soon as they are given a wider outlet, they lose their air on account of the rarity peculiar to water, and so settle down and resume their proper level.

4. Every hot spring has healing properties because it has been boiled with foreign substances, and thus acquires a new useful quality. For example, sulphur springs cure pains in the sinews,

5. There is also a kind of cold water containing natron, found for instance at Penne in the Vestine country, at Cutiliae, and at other similar places. It is taken as a purge and in passing through the bowels reduces scrofulous tumours. Copious springs are found where there are mines of gold, silver, iron, copper, lead, and the like, but they are very harmful. For they contain, like hot springs, sulphur, alum, asphalt, . . . and when it passes into the body in the form of drink, and spreading through the veins reaches the sinews and joints, it expands and hardens them. Hence the sinews, swelling with this expansion, are contracted in length and so give men the cramp or the gout, for the reason that their veins are saturated with very hard, dense, and cold substances.

6. There is also a sort of water which, since it contains . . . that are not perfectly clear, and it floats like a flower on the surface, in colour like purple glass. This may be seen particularly in Athens, where there are aqueducts from places and springs of that sort leading to the city and the port of Piraeus, from which nobody drinks, for the reason mentioned, but they use them for bathing and so forth, and drink from wells, thus avoiding their unwholesomeness. At Troezen it cannot be avoided, because no other kind of water at all is found, except what the Cibdeli furnish, and so in that city all or most of the people have diseases of the feet. At the city of Tarsus in Cilicia is a river named Cydnus, in which gouty people soak their legs and find relief from pain.